commit 2d031e58a4ce72b991e650945166262dafa6bccb
Author: TZGyn <spectator_brethren761@slmails.com>
Date:   Tue Oct 20 00:36:40 2026 +0800

    Add Konverter: a local-only menu bar file converter
    
    Drag files in Finder, hold a modifier, and drop on a wheel of outputs.
    Conversions run entirely on-device through ImageIO, PDFKit, AVFoundation,
    the bundled CLI tools, and optional ffmpeg/LibreOffice.
    
    Includes a --self-test suite (41 checks) and a --convert CLI mode so the
    conversion matrix can be verified without the UI.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3a53013
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,18 @@
+# SwiftPM
+.build/
+.swiftpm/
+
+# App bundle (build artifact, regenerate with ./build-app.sh)
+Konverter.app/
+
+# Secrets
+*.p8
+notary-result.json
+
+# macOS
+.DS_Store
+
+# Xcode
+xcuserdata/
+DerivedData/
+dist/
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..f6aa90d
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,155 @@
+# AGENTS.md
+
+Working notes for `Konverter` — a menu bar file converter for macOS, written in
+Swift with SwiftPM and no external dependencies. Read this before changing the
+drag machinery or the conversion catalog.
+
+## Commands
+
+```bash
+swift build                                   # debug
+swift build -c release
+./.build/debug/Konverter --self-test          # 41 checks, exits non-zero on failure
+./.build/debug/Konverter --convert <files…> --to <ext>
+./.build/debug/Konverter --convert <file> --tool <toolID> --param k=v
+./build-app.sh <version>                      # → Konverter.app (signed)
+./release.sh <version>                        # notarize + staple + zip + sha256
+open Konverter.app
+```
+
+`--self-test` and `--convert` are handled in `AppDelegate.applicationDidFinishLaunching`
+*before* any UI is installed, so they work headlessly and never steal focus. The
+self-test writes its fixtures into a temp directory and cleans up. A `SKIP` line
+means an optional engine (ffmpeg / LibreOffice / `cwebp`) is absent, not a bug;
+a `FAIL` line is a bug.
+
+Keep the self-test green and add a check whenever you add a converter or a
+tool — it is the only automated coverage in the repo.
+
+## Layout
+
+```
+Sources/Konverter/
+  App.swift             @main, AppDelegate, monitor wiring, Services handler
+  CLI.swift             --convert mode
+  SelfTest.swift        the verification suite
+  Core/
+    Format.swift        Format, FileCategory, FileKind, ConversionCatalog
+    Tools.swift         ToolID, ToolField, ToolParams, Timecode
+    Actions.swift       ActionID + FileActions (AirDrop, Float, Copy, …)
+    Settings.swift      UserDefaults-backed preferences, LoginItem
+    JobStore.swift      job queue, progress, reveal, notifications
+    OutputNaming.swift  destination paths, conflict policy
+    Shell.swift         Process wrapper, tool lookup
+    Toolchain.swift     optional engine detection (ffmpeg, soffice, cwebp)
+    WheelOption.swift   WheelItem/WheelKind and wheel construction
+  Drag/
+    DragMonitor.swift   global mouse monitors + drag pasteboard reading
+    WheelController.swift overlay window, geometry, DropCatcher, commit
+    WheelView.swift     SwiftUI radial wheel and list views
+  Convert/
+    Converter.swift     dispatch table + Availability rules
+    ToolRunner.swift    every ToolID implementation
+    ImageConverter.swift, ImageTools.swift
+    PDFConverter.swift, DocumentConverter.swift, TextDocument.swift, Markdown.swift
+    AVConverter.swift, MediaTools.swift, FFmpeg.swift
+    ArchiveConverter.swift, SpreadsheetConverter.swift, EbookConverter.swift
+    SubtitleConverter.swift, Office.swift
+  UI/
+    MenuBar.swift, QuickMenu.swift, PreferencesWindow.swift, OptionsWindow.swift
+    ResultWindow.swift, JobPanel.swift, FloatPanel.swift, Notifier.swift
+```
+
+`Converter.convert(source:to:at:)` handles plain format changes;
+`ToolRunner.run(tool:inputs:params:)` handles transforms. Both funnel through
+`Availability` for the "is the engine present?" question, and both report
+errors as `ConversionError` (a `LocalizedError`) so the CLI and the UI show the
+same wording.
+
+## How the drag wheel works
+
+This is the part with real constraints, so it is worth stating plainly.
+
+1. **Detecting the drag.** `DragMonitor` installs global (and local) monitors for
+   `.leftMouseDragged` etc. Mouse events need **no** permission. On the first
+   drag event it reads `NSPasteboard(name: .drag)` for file URLs. If there are
+   none, it is not a file drag and we ignore it.
+2. **Showing the overlay.** `WheelController.present` creates a borderless
+   `OverlayWindow` at `.screenSaver - 1`, non-key, `ignoresMouseEvents = false`,
+   with a full-screen `DropCatcher` view. A 60 Hz timer polls
+   `NSEvent.mouseLocation` and `NSEvent.modifierFlags` to decide which wheel to
+   show and what is highlighted — because a non-key window cannot read modifier
+   flags from the event stream.
+3. **Consuming the drop.** `DropCatcher` is a real `NSDraggingDestination`. That
+   is what stops Finder from moving the file: Finder hands the drop to us and
+   considers the drag handled. Never replace this with a borderless window that
+   merely *looks* like it is on top — Finder will happily move the file out from
+   under you.
+4. **Ending.** Drop → `commitDrop()` runs the job. Escape, dead-zone drop, or a
+   mouse-up outside the wheel → `cancel()`, which hides the overlay and lets the
+   drag continue wherever it landed.
+5. **Keys are optional.** Escape/arrows/Return come from a *global key* monitor,
+   which does require Accessibility. All of them are also reachable by pointer,
+   so the app must never *require* that permission. Do not move essential
+   behaviour into the key path.
+
+Two ordering traps live here. `NSEvent.modifierFlags` is global state, not the
+event's flags — read it during the tick, not once at drag start. And the wheel
+geometry (`WheelController.geometry`/hit testing) is unit-tested by the
+"Wheel geometry" section of the self-test; if you change the radius or segment
+maths, update those expectations rather than deleting them.
+
+## Conversion gotchas
+
+- **WebP** has no ImageIO encoder on macOS. `WebPEncoder` shells out to `cwebp`,
+  falls back to an ffmpeg with libwebp, and marks the format unavailable
+  otherwise. `sips` cannot write WebP — verified, do not try.
+- **SVG, PSD, RAW** are often undecodable by ImageIO. `Raster.firstImage` falls
+  back to `qlmanage`/Quick Look rasterisation.
+- **Lossless "compression"** (PNG/BMP/TIFF) ignores ImageIO's quality property, so
+  `ImageTools.compress` posterises instead. If you ever reach for `pngquant`,
+  remember it is not a dependency and must stay optional.
+- **PPTX/EPUB/XLSX/DOCX/RTF** are hand-written OOXML/EPUB/zip writers. They are
+  deliberately minimal: enough structure for Word/Numbers/Preview to open them
+  cleanly, no styling round-trip. LibreOffice is used when real layout fidelity
+  matters (PAGES/KEY/NUMBERS/PPT/XLS).
+- **`track.formatDescriptions` is `[Any]`** — you need `as! CMFormatDescription`
+  (`as?` is rejected as always-succeeds). The `load(.formatDescriptions)` API
+  would be nicer but is async and the media-info path is synchronous.
+- Optional engines must always degrade, never crash: absence of ffmpeg or
+  LibreOffice should surface as an unavailable wheel item with a reason, and
+  `Toolchain.missingToolAdvice` supplies the `brew install …` line for the UI.
+
+## Build/bundle notes
+
+- The app is an `LSUIElement` menu bar app; the bundle is assembled by
+  `build-app.sh` with a handwritten `Info.plist`. Do not try to generate it from
+  `Package.swift`, and do not commit `Konverter.app` or `dist/`.
+- `CFBundleIdentifier` is `dev.tzgyn.konverter`. `AppDelegate.terminateOtherInstances()`
+  kills stale copies at launch so the monitors never double up.
+- `Settings` (our class) collides with SwiftUI's `Settings` scene — the scene
+  must be written `SwiftUI.Settings { EmptyView() }`.
+- The Finder Quick Action is an `NSServices` entry calling `convertFiles:userData:error:`
+  on the app delegate. It follows the same path as the menu bar item.
+- `SMAppService.mainApp` powers "open at login".
+
+## Releasing
+
+Notarization is mandatory: an unnotarized build is not a release. `release.sh`
+will not print a sha256 unless Apple accepted the submission, the ticket is
+stapled, and `spctl -a -vv Konverter.app` reports `source=Notarized Developer
+ID`. Never suggest `xattr -dr com.apple.quarantine` or
+`brew install --cask --no-quarantine` as a workaround — fix the signing problem.
+
+Push `main` before `tea releases create` (the tag must point at shipped source),
+then bump `Casks/konverter.rb` in `TZGyn/homebrew-tap` with the new version and
+sha256, and print the upgrade script:
+
+```bash
+brew update
+brew upgrade --cask konverter
+```
+
+Credentials: `~/.config/kapture/AuthKey_K5KXMMSB28.p8`, key id `K5KXMMSB28`,
+issuer `3e25e5dc-8b75-453f-a71c-c7f3feaac628`, team `RX6767S6BW`. Never commit
+the key.
diff --git a/Package.swift b/Package.swift
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index 0000000..c193df3
--- /dev/null
+++ b/Package.swift
@@ -0,0 +1,13 @@
+// swift-tools-version: 5.9
+import PackageDescription
+
+let package = Package(
+    name: "Konverter",
+    platforms: [.macOS(.v13)],
+    targets: [
+        .executableTarget(
+            name: "Konverter",
+            path: "Sources/Konverter"
+        )
+    ]
+)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..814dc89
--- /dev/null
+++ b/README.md
@@ -0,0 +1,180 @@
+# Konverter
+
+A macOS menu bar file converter in the spirit of [Tangerine](https://tangerineformac.com):
+drag a file in Finder, hold a modifier key, get a wheel of outputs around the
+cursor, drop on one, and the converted file appears next to the original.
+Everything runs locally — no uploads, no accounts, no analytics.
+
+<p align="center">
+  <em>Shift = convert · Command (+Shift) = tools · Control = actions</em>
+</p>
+
+## Using it
+
+1. Launch Konverter. It lives in the menu bar (`LSUIElement`, no Dock icon).
+2. In Finder, drag one or more files (folders work for archives).
+3. **Hold a trigger key while dragging** — the wheel fades in under the pointer:
+   - **Shift ⇧** — conversion targets (`PNG`, `JPG`, `PDF`, `MP4`, `ZIP`, …).
+   - **Command ⌘ + Shift** — file tools (`Compress`, `Resize`, `Trim`,
+     `Watermark`, `Merge`, `Extract`, …), each with its own small form.
+   - **Control ⌃** — actions (`AirDrop`, `Float`, `Copy`, `Move`, `Copy Path`,
+     `Terminal`, `Reveal`).
+4. Move the pointer onto a segment (or use ←/→ and Return) and **drop**.
+   Dropping on the dead zone in the middle, pressing Escape, or dropping the
+   file anywhere else cancels and lets Finder do its normal thing.
+
+The wheel also works without dragging: the menu bar item and the Finder Quick
+Action **Convert with Konverter…** open the same options as a menu.
+
+Keyboard/pointer alone is enough to use it. The optional keys (Escape, arrows,
+Return) come from a global key monitor, so they need Accessibility permission —
+without it the wheel still works by pointer, it just cannot read those keys.
+
+### Preferences
+
+Trigger keys (Shift/Command/Control/Option/fn), wheel style (radial/list),
+radius, labels, dimming, output folder (beside the original or a chosen
+folder), conflict policy (keep both / replace), progress window, reveal when
+finished, sound, use of external tools, and open at login. Stored in
+`UserDefaults` under the `konverter.` prefix.
+
+## What it converts
+
+94 input extensions are recognised. Outputs offered per kind of file:
+
+| Input kind | Outputs |
+| --- | --- |
+| Image | PNG, JPG, HEIC, WebP, TIFF, BMP, GIF, AVIF, PDF |
+| Video | MP4, MOV, MKV, WebM, AVI, WMV, GIF, MP3, M4A, WAV |
+| Audio | MP3, M4A, WAV, FLAC, OGG, Opus, AIFF, WMA |
+| PDF | DOCX, PPTX, XLSX, JPG, PNG, EPUB, TXT, MD, HTML |
+| Document | DOCX, MD, TXT, RTF, HTML, EPUB, PDF |
+| Slides | PDF, JPG, PNG |
+| Spreadsheet | XLSX, ODS, CSV, TSV, PDF |
+| Ebook | TXT, HTML, MD, PDF |
+| Subtitle | SRT, VTT, TXT |
+| Archive / folder | ZIP, TAR, GZIP |
+
+Plus 38 tools:
+
+| Group | Tools |
+| --- | --- |
+| Image | Compress, Resize, Crop, Rotate, Flip, Grayscale, Strip Metadata, Watermark, Read QR |
+| Video | Compress, Trim, Mute, Speed, Snapshot, To GIF, Resize |
+| Audio | Trim, Normalize, Channels, Speed, Bleep, Compress |
+| PDF | Merge, Split, Rotate, Compress, Encrypt, Decrypt, Images to PDF, Collage, Extract Text |
+| Document | To PDF, Statistics |
+| Spreadsheet | To CSV |
+| Subtitle | Shift Time |
+| Archive | Extract, List Contents |
+| Any | Info |
+
+### Engines and fallbacks
+
+| Layer | Used for | Ships with macOS |
+| --- | --- | --- |
+| ImageIO / Core Graphics | raster image decode/encode | yes |
+| PDFKit / Core Text | PDF read/write, text extraction | yes |
+| AVFoundation | MP4/MOV/M4A/WAV/AIFF/GIF | yes |
+| `textutil`, `afconvert`, `ditto`, `tar`, `gzip`, `zip` | documents, audio, archives | yes |
+| Hand-written XLSX / EPUB / Markdown / CSV / TSV / SRT-VTT | office and ebook plumbing | yes |
+| ffmpeg / ffprobe | MKV, WebM, AVI, WMV, MP3, FLAC, OGG, Opus, WMA, bleep | optional |
+| LibreOffice | PAGES, KEY, NUMBERS, PPT, PPTX, XLS, ODS | optional |
+| `cwebp` | WebP encoding | optional |
+
+Optional helpers are detected once at launch and are only ever *additive*: a
+format whose engine is missing shows as unavailable in the wheel (with the
+reason) instead of failing after you drop. Install them with:
+
+```bash
+brew install ffmpeg webp          # cwebp comes from the webp formula
+brew install --cask libreoffice
+```
+
+Notes on specific formats:
+
+- **WebP out** needs `cwebp` or an ffmpeg built with libwebp. ImageIO on macOS
+  has no WebP encoder, and `sips` cannot write it either.
+- **SVG / PSD / RAW in** are rasterised through Quick Look (`qlmanage`) when
+  ImageIO refuses them.
+- **PAGES / KEY / NUMBERS out** only exist through LibreOffice. In Safari-style
+  document conversion, the Apple formats keep their layout via LibreOffice's
+  filter, not a hand-rolled writer.
+- **Compressing a PNG** has no lossy quality knob, so the slider drives colour
+  depth (posterisation) instead — a real size drop, at the cost of banding at
+  low settings.
+
+## Building
+
+Requires Xcode (Swift 6 toolchain) and macOS 13+.
+
+```bash
+swift build                       # debug binary
+swift build -c release
+
+./.build/debug/Konverter --self-test   # 41 checks over every engine
+./.build/debug/Konverter --convert photo.heic --to png
+./.build/debug/Konverter --convert clip.mov --tool trimVideo \
+    --param start=0:02 --param end=0:05
+./.build/debug/Konverter --convert image.png --tool compressImage --param quality=50
+```
+
+`--self-test` builds its own fixtures in a temp directory and asserts that each
+engine produces a non-empty, plausible file. Skips (printed as `SKIP`) mean an
+optional engine is absent on this machine.
+
+Build the app bundle (ad-hoc signed when no Developer ID identity is present):
+
+```bash
+./build-app.sh 0.1.0            # → Konverter.app, signed with Developer ID
+open Konverter.app
+```
+
+## Releasing
+
+```bash
+./release.sh 0.1.0              # build → sign → notarize → staple → zip + sha256
+```
+
+`release.sh` refuses to hand back a build that is not notarized and stapled;
+it also verifies `spctl -a -vv Konverter.app` reports
+`source=Notarized Developer ID` before printing the sha256. Notary credentials
+default to the shared App Store Connect key and can be overridden with
+`KONVERTER_NOTARY_API_KEY_PATH`, `KONVERTER_NOTARY_API_KEY_ID`, and
+`KONVERTER_NOTARY_API_ISSUER`.
+
+Then tag, publish, and attach the zip:
+
+```bash
+git tag v0.1.0 && git push origin v0.1.0
+tea releases create --tag v0.1.0 --title "Konverter 0.1.0" \
+  --note "<what changed>" --asset dist/Konverter.zip \
+  --repo TZGyn/konverter --login gitea.tzgyn.dev
+```
+
+## Install (Homebrew)
+
+```bash
+brew tap TZGyn/tap https://gitea.tzgyn.dev/TZGyn/homebrew-tap.git
+brew trust TZGyn/tap
+brew install --cask konverter
+```
+
+Upgrade script:
+
+```bash
+brew update
+brew upgrade --cask konverter
+```
+
+## Privacy
+
+Nothing leaves the machine. There is no networking code in the app, no
+telemetry, and no third-party dependencies in `Package.swift`. Conversions are
+performed by Apple frameworks, the bundled CLI tools, and (optionally) local
+`ffmpeg` / LibreOffice.
+
+## Development docs
+
+`AGENTS.md` covers the architecture, the drag/wheel mechanics, and the sharp
+edges worth knowing before changing the code.
diff --git a/Sources/Konverter/App.swift b/Sources/Konverter/App.swift
new file mode 100644
index 0000000..245b90c
--- /dev/null
+++ b/Sources/Konverter/App.swift
@@ -0,0 +1,91 @@
+import AppKit
+import SwiftUI
+
+@main
+struct KonverterApp: App {
+    @NSApplicationDelegateAdaptor(AppDelegate.self) private var appDelegate
+
+    var body: some Scene {
+        // A menu bar app: no windows of its own. Settings are a custom window
+        // so the app can be opened from the status item on any space.
+        SwiftUI.Settings { EmptyView() }
+    }
+}
+
+final class AppDelegate: NSObject, NSApplicationDelegate {
+    private let menuBar = MenuBarController()
+
+    func applicationDidFinishLaunching(_ notification: Notification) {
+        if CommandLine.arguments.contains("--self-test") {
+            exit(SelfTest.run())
+        }
+        if CommandLine.arguments.contains("--convert") {
+            exit(CLI.run())
+        }
+
+        terminateOtherInstances()
+
+        menuBar.install()
+
+        DragMonitor.shared.onBegan = { urls in
+            WheelController.shared.begin(urls: urls)
+        }
+        DragMonitor.shared.onTick = { _, location, modifiers in
+            guard Settings.shared.enabled else { return }
+            WheelController.shared.tick(location: location, modifiers: modifiers)
+        }
+        DragMonitor.shared.onEnded = { _ in
+            WheelController.shared.end()
+        }
+        DragMonitor.shared.onKey = { keyCode, modifiers in
+            WheelController.shared.handleKey(keyCode, modifiers: modifiers)
+        }
+        DragMonitor.shared.start()
+
+        NSApp.servicesProvider = self
+        NSUpdateDynamicServices()
+
+        // Warm the Quick Look machinery so the first Float is instant.
+        DispatchQueue.main.async {
+            _ = NSWorkspace.shared
+        }
+    }
+
+    func applicationWillTerminate(_ notification: Notification) {
+        DragMonitor.shared.stop()
+        WheelController.shared.cancel()
+    }
+
+    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
+        false
+    }
+
+    private func terminateOtherInstances() {
+        let identifier = Bundle.main.bundleIdentifier ?? "dev.tzgyn.konverter"
+        let mine = ProcessInfo.processInfo.processIdentifier
+        for other in NSRunningApplication.runningApplications(withBundleIdentifier: identifier)
+        where other.processIdentifier != mine {
+            other.forceTerminate()
+        }
+    }
+
+    /// Finder Quick Action / Services entry. The wheel needs a pointer to sit
+    /// under, so this opens the same options as a native menu.
+    @objc func convertFiles(
+        _ pasteboard: NSPasteboard,
+        userData: String,
+        error: AutoreleasingUnsafeMutablePointer<NSString>
+    ) {
+        let urls = (pasteboard.readObjects(
+            forClasses: [NSURL.self],
+            options: [.urlReadingFileURLsOnly: true]
+        ) as? [URL]) ?? []
+        guard !urls.isEmpty else {
+            error.pointee = "No files were passed to Konverter." as NSString
+            return
+        }
+        DispatchQueue.main.async {
+            QuickMenu.show(urls: urls, at: NSEvent.mouseLocation)
+        }
+    }
+}
diff --git a/Sources/Konverter/CLI.swift b/Sources/Konverter/CLI.swift
new file mode 100644
index 0000000..c428103
--- /dev/null
+++ b/Sources/Konverter/CLI.swift
@@ -0,0 +1,80 @@
+import AppKit
+import Foundation
+
+/// Headless conversion, used for verification and scripting:
+///
+///     Konverter --convert a.png b.pdf --to jpg
+///     Konverter --convert clip.mov --tool trimVideo --param start=0:02 --param end=0:05
+enum CLI {
+    static func run() -> Int32 {
+        let arguments = Array(CommandLine.arguments.dropFirst())
+
+        guard let convertIndex = arguments.firstIndex(of: "--convert") else {
+            FileHandle.standardError.write(Data("usage: Konverter --convert <files…> --to <ext>\n".utf8))
+            return 2
+        }
+
+        var files: [URL] = []
+        var target: Format?
+        var tool: ToolID?
+        var params = ToolParams()
+
+        var index = convertIndex + 1
+        while index < arguments.count {
+            let argument = arguments[index]
+            switch argument {
+            case "--to":
+                index += 1
+                if index < arguments.count { target = Format(rawValue: arguments[index]) }
+            case "--tool":
+                index += 1
+                if index < arguments.count { tool = ToolID(rawValue: arguments[index]) }
+            case "--param":
+                index += 1
+                if index < arguments.count {
+                    let pair = arguments[index].split(separator: "=", maxSplits: 1).map(String.init)
+                    if pair.count == 2 { params[pair[0]] = pair[1] }
+                }
+            default:
+                if !argument.hasPrefix("--") {
+                    files.append(URL(fileURLWithPath: argument))
+                }
+            }
+            index += 1
+        }
+
+        guard !files.isEmpty else {
+            FileHandle.standardError.write(Data("no input files\n".utf8))
+            return 2
+        }
+
+        do {
+            if let tool {
+                let outcome = try ToolRunner.run(tool: tool, inputs: files, params: params)
+                if let message = outcome.message {
+                    print(message)
+                }
+                for output in outcome.outputs { print(output.path) }
+                return outcome.outputs.isEmpty && outcome.message == nil ? 1 : 0
+            }
+
+            guard let target else {
+                FileHandle.standardError.write(Data("--to is required\n".utf8))
+                return 2
+            }
+
+            var written: [URL] = []
+            for file in files {
+                let destination = OutputNaming.destination(for: file, format: target)
+                let outputs = try Converter.convert(source: file, to: target, at: destination)
+                written.append(contentsOf: outputs)
+            }
+            for output in written { print(output.path) }
+            return written.isEmpty ? 1 : 0
+        } catch {
+            let message = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
+            FileHandle.standardError.write(Data((message + "\n").utf8))
+            return 1
+        }
+    }
+}
diff --git a/Sources/Konverter/Convert/AVConverter.swift b/Sources/Konverter/Convert/AVConverter.swift
new file mode 100644
index 0000000..c49fa31
--- /dev/null
+++ b/Sources/Konverter/Convert/AVConverter.swift
@@ -0,0 +1,368 @@
+import AVFoundation
+import CoreGraphics
+import Foundation
+import ImageIO
+
+/// Audio and video, mostly through AVFoundation. Formats Apple cannot write
+/// (MKV, WebM, AVI, WMV, MP3, FLAC, OGG, Opus, WMA) are delegated to ffmpeg
+/// when it is installed — see `FFmpeg`.
+enum AVConverter {
+
+    // MARK: - Probing
+
+    static func duration(_ url: URL) -> Double? {
+        let asset = AVURLAsset(url: url, options: [AVURLAssetPreferPreciseDurationAndTimingKey: true])
+        let seconds = CMTimeGetSeconds(asset.duration)
+        return seconds.isFinite && seconds > 0 ? seconds : nil
+    }
+
+    /// Uses the synchronously loaded track list; called only while building the
+    /// drag wheel, so it must not await.
+    static func trackSummary(_ url: URL) -> (video: Bool, audio: Bool) {
+        let asset = AVURLAsset(url: url)
+        var video = false
+        var audio = false
+        for track in asset.tracks {
+            switch track.mediaType {
+            case .video where track.naturalSize.height > 0: video = true
+            case .audio: audio = true
+            default: break
+            }
+        }
+        return (video, audio)
+    }
+
+    // MARK: - Conversion
+
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        quality: String = "Medium",
+        bitrate: String = "128",
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try cancellation?.check()
+
+        switch format {
+        case .gif:
+            try makeGIF(source: source, at: destination, fps: 12, maxWidth: 480, cancellation: cancellation, progress: progress)
+            return
+        case .mp4, .mov, .m4v:
+            try exportWithSession(
+                source: source,
+                destination: destination,
+                fileType: format == .mov ? .mov : .mp4,
+                preset: videoPreset(for: quality),
+                cancellation: cancellation,
+                progress: progress
+            )
+            return
+        case .m4a, .mp3:
+            if format == .m4a {
+                try exportWithSession(
+                    source: source,
+                    destination: destination,
+                    fileType: .m4a,
+                    preset: AVAssetExportPresetAppleM4A,
+                    cancellation: cancellation,
+                    progress: progress
+                )
+                return
+            }
+            try FFmpeg.convert(source: source, to: format, at: destination, bitrate: bitrate, cancellation: cancellation, progress: progress)
+            return
+        default:
+            // Everything else: try ffmpeg, then CoreAudio, then AVFoundation.
+            if Toolchain.hasFFmpeg, Settings.shared.useExternalTools {
+                try FFmpeg.convert(source: source, to: format, at: destination, bitrate: bitrate, cancellation: cancellation, progress: progress)
+                return
+            }
+            if format == .wav || format == .aiff {
+                try CoreAudio.convert(source: source, to: format, at: destination, cancellation: cancellation)
+                return
+            }
+            throw ConversionError.missingTool(
+                "\(format.displayName) needs ffmpeg. Install it with: brew install ffmpeg"
+            )
+        }
+    }
+
+    static func videoPreset(for quality: String) -> String {
+        switch quality {
+        case "Low": return AVAssetExportPreset960x540
+        case "High": return AVAssetExportPreset1920x1080
+        default: return AVAssetExportPreset1280x720
+        }
+    }
+
+    // MARK: - Tools
+
+    static func trim(
+        source: URL,
+        at destination: URL,
+        start: Double,
+        end: Double?,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        guard let session = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetHighestQuality) else {
+            throw ConversionError.failed("Could not prepare a trim for \(source.lastPathComponent).")
+        }
+        let duration = CMTimeGetSeconds(asset.duration)
+        let startTime = max(0, min(start, duration))
+        let endTime = min(end ?? duration, duration)
+        guard endTime > startTime else {
+            throw ConversionError.failed("The trim range is empty.")
+        }
+        session.timeRange = CMTimeRange(
+            start: CMTime(seconds: startTime, preferredTimescale: 600),
+            end: CMTime(seconds: endTime, preferredTimescale: 600)
+        )
+        try run(session: session, destination: destination, fileType: destination.pathExtension == "mov" ? .mov : .mp4, cancellation: cancellation, progress: progress)
+    }
+
+    /// Rebuilds the file with the audio track dropped.
+    static func mute(
+        source: URL,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        let composition = AVMutableComposition()
+        var inserted = false
+        for track in asset.tracks where track.mediaType == .video {
+            guard let target = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid) else { continue }
+            try target.insertTimeRange(CMTimeRange(start: .zero, duration: asset.duration), of: track, at: .zero)
+            target.preferredTransform = track.preferredTransform
+            inserted = true
+        }
+        guard inserted else { throw ConversionError.failed("No video track to keep.") }
+        try exportComposition(composition, at: destination, cancellation: cancellation, progress: progress)
+    }
+
+    static func changeSpeed(
+        source: URL,
+        at destination: URL,
+        rate: Double,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        guard rate > 0 else { throw ConversionError.failed("Speed must be greater than zero.") }
+        let asset = AVURLAsset(url: source)
+        let composition = AVMutableComposition()
+        let duration = asset.duration
+        for track in asset.tracks {
+            guard track.mediaType == .video || track.mediaType == .audio else { continue }
+            guard let target = composition.addMutableTrack(withMediaType: track.mediaType, preferredTrackID: kCMPersistentTrackID_Invalid) else { continue }
+            try target.insertTimeRange(CMTimeRange(start: .zero, duration: duration), of: track, at: .zero)
+            if track.mediaType == .video {
+                target.preferredTransform = track.preferredTransform
+            } else {
+                target.scaleTimeRange(CMTimeRange(start: .zero, duration: duration), toDuration: CMTimeMultiplyByFloat64(duration, multiplier: 1 / rate))
+            }
+        }
+        for track in composition.tracks where track.mediaType == .video {
+            track.scaleTimeRange(CMTimeRange(start: .zero, duration: duration), toDuration: CMTimeMultiplyByFloat64(duration, multiplier: 1 / rate))
+        }
+        try exportComposition(composition, at: destination, cancellation: cancellation, progress: progress, audioPitch: .varispeed)
+    }
+
+    static func resize(
+        source: URL,
+        at destination: URL,
+        width: Int,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        guard let track = asset.tracks(withMediaType: .video).first else {
+            throw ConversionError.failed("No video track to resize.")
+        }
+        let natural = track.naturalSize.applying(track.preferredTransform)
+        let sourceSize = CGSize(width: abs(natural.width), height: abs(natural.height))
+        guard sourceSize.width > 0 else { throw ConversionError.failed("Unknown video size.") }
+        let scale = CGFloat(width) / sourceSize.width
+        let renderSize = CGSize(width: CGFloat(width).rounded(), height: (sourceSize.height * scale).rounded())
+
+        let composition = AVMutableComposition()
+        guard let videoTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid) else {
+            throw ConversionError.failed("Could not build the resize composition.")
+        }
+        let range = CMTimeRange(start: .zero, duration: asset.duration)
+        try videoTrack.insertTimeRange(range, of: track, at: .zero)
+        if let audio = asset.tracks(withMediaType: .audio).first,
+           let audioTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: kCMPersistentTrackID_Invalid) {
+            try audioTrack.insertTimeRange(range, of: audio, at: .zero)
+        }
+
+        let instruction = AVMutableVideoCompositionInstruction()
+        instruction.timeRange = range
+        let layer = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
+        let transform = track.preferredTransform.concatenating(CGAffineTransform(scaleX: scale, y: scale))
+        layer.setTransform(transform, at: .zero)
+        instruction.layerInstructions = [layer]
+
+        let videoComposition = AVMutableVideoComposition()
+        videoComposition.renderSize = renderSize
+        videoComposition.frameDuration = CMTime(value: 1, timescale: 30)
+        videoComposition.instructions = [instruction]
+
+        try exportComposition(composition, at: destination, cancellation: cancellation, progress: progress, videoComposition: videoComposition)
+    }
+
+    static func snapshot(
+        source: URL,
+        at destination: URL,
+        time: Double,
+        cancellation: Cancellation? = nil
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        let generator = AVAssetImageGenerator(asset: asset)
+        generator.appliesPreferredTrackTransform = true
+        generator.requestedTimeToleranceBefore = .zero
+        generator.requestedTimeToleranceAfter = .zero
+        try cancellation?.check()
+        let image = try generator.copyCGImage(at: CMTime(seconds: time, preferredTimescale: 600), actualTime: nil)
+        try Raster.write(image, to: destination, format: .png, quality: 1, metadata: nil)
+    }
+
+    /// Frame-by-frame GIF. Long clips are capped so the result stays small.
+    static func makeGIF(
+        source: URL,
+        at destination: URL,
+        fps: Int,
+        maxWidth: Int,
+        maxDuration: Double = 20,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        let duration = min(CMTimeGetSeconds(asset.duration), maxDuration)
+        guard duration > 0 else { throw ConversionError.failed("Nothing to animate.") }
+
+        let generator = AVAssetImageGenerator(asset: asset)
+        generator.appliesPreferredTrackTransform = true
+        generator.maximumSize = CGSize(width: maxWidth, height: maxWidth)
+        generator.requestedTimeToleranceBefore = CMTime(seconds: 0.05, preferredTimescale: 600)
+        generator.requestedTimeToleranceAfter = CMTime(seconds: 0.05, preferredTimescale: 600)
+
+        guard let output = CGImageDestinationCreateWithURL(destination as CFURL, "com.compuserve.gif" as CFString, 0, nil) else {
+            throw ConversionError.failed("Could not create \(destination.lastPathComponent).")
+        }
+        CGImageDestinationSetProperties(output, [
+            kCGImagePropertyGIFDictionary: [kCGImagePropertyGIFLoopCount: 0]
+        ] as CFDictionary)
+
+        let frameCount = max(1, Int(duration * Double(fps)))
+        let frameDuration = 1.0 / Double(fps)
+        for index in 0..<frameCount {
+            try cancellation?.check()
+            let time = CMTime(seconds: Double(index) * frameDuration, preferredTimescale: 600)
+            if let image = try? generator.copyCGImage(at: time, actualTime: nil) {
+                CGImageDestinationAddImage(output, image, [
+                    kCGImagePropertyGIFDictionary: [kCGImagePropertyGIFDelayTime: frameDuration]
+                ] as CFDictionary)
+            }
+            progress?(Double(index + 1) / Double(frameCount))
+        }
+        guard CGImageDestinationFinalize(output) else {
+            throw ConversionError.failed("Writing the GIF failed.")
+        }
+    }
+
+    // MARK: - Internals
+
+    private static func exportComposition(
+        _ composition: AVComposition,
+        at destination: URL,
+        cancellation: Cancellation?,
+        progress: ((Double) -> Void)?,
+        audioPitch: AVAudioTimePitchAlgorithm? = nil,
+        videoComposition: AVVideoComposition? = nil
+    ) throws {
+        let fileType: AVFileType = destination.pathExtension == "mov"
+            ? .mov
+            : (destination.pathExtension == "m4a" ? .m4a : .mp4)
+        guard let session = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality) else {
+            throw ConversionError.failed("Could not prepare the export.")
+        }
+        if let audioPitch { session.audioTimePitchAlgorithm = audioPitch }
+        if let videoComposition { session.videoComposition = videoComposition }
+        try run(session: session, destination: destination, fileType: fileType, cancellation: cancellation, progress: progress)
+    }
+
+    private static func exportWithSession(
+        source: URL,
+        destination: URL,
+        fileType: AVFileType,
+        preset: String,
+        cancellation: Cancellation?,
+        progress: ((Double) -> Void)?
+    ) throws {
+        let asset = AVURLAsset(url: source)
+        guard let session = AVAssetExportSession(asset: asset, presetName: preset) else {
+            throw ConversionError.failed("This file cannot be exported with the \(preset) preset.")
+        }
+        try run(session: session, destination: destination, fileType: fileType, cancellation: cancellation, progress: progress)
+    }
+
+    private final class ErrorBox: @unchecked Sendable {
+        private let lock = NSLock()
+        private var value: Error?
+        func set(_ error: Error) { lock.lock(); value = error; lock.unlock() }
+        func get() -> Error? { lock.lock(); defer { lock.unlock() }; return value }
+    }
+
+    private static func run(
+        session: AVAssetExportSession,
+        destination: URL,
+        fileType: AVFileType,
+        cancellation: Cancellation?,
+        progress: ((Double) -> Void)?
+    ) throws {
+        if FileManager.default.fileExists(atPath: destination.path) {
+            try? FileManager.default.removeItem(at: destination)
+        }
+
+        let box = ErrorBox()
+        let ready = DispatchSemaphore(value: 0)
+
+        if #available(macOS 15.0, *) {
+            let session = session
+            Task.detached(priority: .userInitiated) {
+                do {
+                    try await session.export(to: destination, as: fileType)
+                } catch {
+                    box.set(error)
+                }
+                ready.signal()
+            }
+        } else {
+            session.outputURL = destination
+            session.outputFileType = fileType
+            session.shouldOptimizeForNetworkUse = false
+            session.exportAsynchronously { ready.signal() }
+        }
+
+        // Poll for progress and cancellation while the export runs.
+        while ready.wait(timeout: .now() + 0.2) == .timedOut {
+            if cancellation?.isCancelled == true {
+                session.cancelExport()
+                throw CancellationError()
+            }
+            progress?(Double(session.progress))
+        }
+
+        try cancellation?.check()
+        if let error = box.get() { throw ConversionError.failed(error.localizedDescription) }
+        if session.status == .failed {
+            throw ConversionError.failed(session.error?.localizedDescription ?? "Export failed.")
+        }
+        if session.status == .cancelled { throw CancellationError() }
+        progress?(1)
+    }
+}
diff --git a/Sources/Konverter/Convert/ArchiveConverter.swift b/Sources/Konverter/Convert/ArchiveConverter.swift
new file mode 100644
index 0000000..aba6285
--- /dev/null
+++ b/Sources/Konverter/Convert/ArchiveConverter.swift
@@ -0,0 +1,142 @@
+import Foundation
+
+/// ZIP/TAR/GZIP via the system's own tools (`ditto`, `tar`, `gzip`), which is
+/// both faster and more correct than rolling our own containers.
+enum ArchiveConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try cancellation?.check()
+        progress?(0.1)
+        switch format {
+        case .zip:
+            try makeZip(source: source, at: destination, cancellation: cancellation)
+        case .tar:
+            try Shell.run(
+                Toolchain.tar,
+                ["-cf", destination.path, "-C", source.deletingLastPathComponent().path, source.lastPathComponent],
+                cancellation: cancellation
+            )
+        case .gzip:
+            try makeGzip(source: source, at: destination, cancellation: cancellation)
+        default:
+            throw ConversionError.unsupported("\(format.displayName) is not an archive format Konverter writes.")
+        }
+        progress?(1)
+    }
+
+    private static func makeZip(source: URL, at destination: URL, cancellation: Cancellation?) throws {
+        var arguments = ["-c", "-k", "--sequesterRsrc"]
+        if source.hasDirectoryPath || isDirectory(source) {
+            arguments.append("--keepParent")
+        }
+        arguments += [source.path, destination.path]
+        try Shell.run(Toolchain.ditto, arguments, cancellation: cancellation)
+    }
+
+    private static func makeGzip(source: URL, at destination: URL, cancellation: Cancellation?) throws {
+        // gzip only compresses a single stream, so a folder is tarred first and
+        // the pair is squeezed into one .gz — the classic .tar.gz shape.
+        if isDirectory(source) {
+            let staging = FileManager.default.temporaryDirectory
+                .appendingPathComponent("konverter-\(UUID().uuidString).tar")
+            defer { try? FileManager.default.removeItem(at: staging) }
+            try Shell.run(
+                Toolchain.tar,
+                ["-cf", staging.path, "-C", source.deletingLastPathComponent().path, source.lastPathComponent],
+                cancellation: cancellation
+            )
+            let data = try Shell.runData(Toolchain.gzip, ["-n", "-9", "-c", staging.path], cancellation: cancellation)
+            try data.write(to: destination)
+        } else {
+            let data = try Shell.runData(Toolchain.gzip, ["-n", "-9", "-c", source.path], cancellation: cancellation)
+            try data.write(to: destination)
+        }
+    }
+
+    /// Expands an archive into `directory`, returning the folder that callers
+    /// should reveal.
+    @discardableResult
+    static func extract(
+        source: URL,
+        into directory: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws -> URL {
+        try cancellation?.check()
+        try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+        progress?(0.2)
+
+        let ext = source.pathExtension.lowercased()
+        switch ext {
+        case "zip":
+            try Shell.run(Toolchain.ditto, ["-x", "-k", source.path, directory.path], cancellation: cancellation)
+        case "tar", "tgz":
+            try Shell.run(Toolchain.tar, ["-xf", source.path, "-C", directory.path], cancellation: cancellation)
+        case "gz":
+            let inner = source.deletingPathExtension().lastPathComponent
+            if inner.lowercased().hasSuffix(".tar") {
+                try Shell.run(Toolchain.tar, ["-xzf", source.path, "-C", directory.path], cancellation: cancellation)
+            } else {
+                let data = try Shell.runData(Toolchain.gunzip, ["-c", source.path], cancellation: cancellation)
+                try data.write(to: directory.appendingPathComponent(inner))
+            }
+        default:
+            try extractWithLibarchive(source: source, into: directory, cancellation: cancellation)
+        }
+        progress?(1)
+        return directory
+    }
+
+    /// RAR/7z/BZip2/XZ: libarchive (bsdtar) reads most of them; `unar` is used
+    /// when present because it handles RAR5 and encrypted archives better.
+    private static func extractWithLibarchive(source: URL, into directory: URL, cancellation: Cancellation?) throws {
+        if let unar = Shell.find("unar", extraPaths: ["/opt/homebrew/bin", "/usr/local/bin"]) {
+            try Shell.run(unar, ["-quiet", "-force-overwrite", "-output-directory", directory.path, source.path], cancellation: cancellation)
+            return
+        }
+        do {
+            try Shell.run(Toolchain.tar, ["-xf", source.path, "-C", directory.path], cancellation: cancellation)
+            return
+        } catch {
+            throw ConversionError.missingTool(
+                "Konverter cannot open .\(source.pathExtension) archives. Install unar (brew install unar) and try again."
+            )
+        }
+    }
+
+    static func list(_ source: URL) throws -> String {
+        switch source.pathExtension.lowercased() {
+        case "zip":
+            let result = try Shell.run(Toolchain.unzip, ["-l", source.path])
+            return result.stdout
+        case "tar", "tgz":
+            return try Shell.run(Toolchain.tar, ["-tf", source.path]).stdout
+        case "gz":
+            let size = (try? FileManager.default.attributesOfItem(atPath: source.path)[.size] as? Int) ?? 0
+            return """
+            GZIP stream
+            Compressed size: \(ByteCountFormatter.string(fromByteCount: Int64(size ?? 0), countStyle: .file))
+            Inner name: \(source.deletingPathExtension().lastPathComponent)
+            """
+        default:
+            let result = try? Shell.run(Toolchain.tar, ["-tf", source.path])
+            guard let stdout = result?.stdout else {
+                throw ConversionError.missingTool("Cannot list .\(source.pathExtension) archives without unar.")
+            }
+            return stdout
+        }
+    }
+
+    static func isArchive(_ url: URL) -> Bool {
+        FileKind.category(of: url) == .archive
+    }
+
+    private static func isDirectory(_ url: URL) -> Bool {
+        (try? url.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) == true
+    }
+}
diff --git a/Sources/Konverter/Convert/Converter.swift b/Sources/Konverter/Convert/Converter.swift
new file mode 100644
index 0000000..bc7ebad
--- /dev/null
+++ b/Sources/Konverter/Convert/Converter.swift
@@ -0,0 +1,176 @@
+import Foundation
+import PDFKit
+
+/// Whether an output format can actually be produced on this Mac, and why not
+/// when it cannot. The wheel uses this to mark options as unavailable instead
+/// of failing after the user has already committed to a drop.
+struct Availability {
+    let isAvailable: Bool
+    let reason: String?
+
+    static let ok = Availability(isAvailable: true, reason: nil)
+
+    static func unavailable(_ reason: String) -> Availability {
+        Availability(isAvailable: false, reason: reason)
+    }
+}
+
+/// Front door for format conversions: picks the engine, handles formats that
+/// produce more than one file, and reports a useful reason when nothing can.
+enum Converter {
+    @discardableResult
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        quality: Double = 0.9,
+        mediaQuality: String = "Medium",
+        audioBitrate: String = "192",
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws -> [URL] {
+        try cancellation?.check()
+        let category = FileKind.category(of: source)
+
+        switch category {
+        case .image:
+            try ImageConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                quality: quality,
+                cancellation: cancellation
+            )
+            progress?(1)
+            return [destination]
+
+        case .video, .audio:
+            try AVConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                quality: mediaQuality,
+                bitrate: audioBitrate,
+                cancellation: cancellation,
+                progress: progress
+            )
+            return [destination]
+
+        case .pdf:
+            switch format {
+            case .jpg, .png:
+                let directory = OutputNaming.artifactDirectory(for: source, suffix: " \(format.displayName)")
+                return try PDFConverter.renderPages(
+                    source,
+                    to: format,
+                    into: directory,
+                    dpi: 300,
+                    cancellation: cancellation,
+                    progress: progress
+                )
+            case .pptx, .xlsx:
+                try Office.convert(source, to: format, at: destination, cancellation: cancellation)
+                progress?(1)
+                return [destination]
+            case .pdf:
+                guard let document = PDFDocument(url: source) else {
+                    throw ConversionError.unreadable(source.lastPathComponent)
+                }
+                guard document.write(to: destination) else {
+                    throw ConversionError.failed("Could not rewrite the PDF.")
+                }
+                progress?(1)
+                return [destination]
+            default:
+                try DocumentConverter.convert(
+                    source: source,
+                    to: format,
+                    at: destination,
+                    cancellation: cancellation,
+                    progress: progress
+                )
+                return [destination]
+            }
+
+        case .document, .spreadsheet:
+            try DocumentConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                cancellation: cancellation,
+                progress: progress
+            )
+            return [destination]
+
+        case .slides:
+            try SlidesConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                cancellation: cancellation,
+                progress: progress
+            )
+            if format == .png || format == .jpg {
+                let directory = OutputNaming.artifactDirectory(for: source, suffix: " \(format.displayName)")
+                let files = (try? FileManager.default.contentsOfDirectory(at: directory, includingPropertiesForKeys: nil)) ?? []
+                return files.sorted { $0.lastPathComponent < $1.lastPathComponent }
+            }
+            return [destination]
+
+        case .ebook:
+            try EbookConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                cancellation: cancellation,
+                progress: progress
+            )
+            return [destination]
+
+        case .subtitle:
+            try SubtitleConverter.convert(source: source, to: format, at: destination, cancellation: cancellation)
+            progress?(1)
+            return [destination]
+
+        case .archive:
+            try ArchiveConverter.convert(
+                source: source,
+                to: format,
+                at: destination,
+                cancellation: cancellation,
+                progress: progress
+            )
+            return [destination]
+
+        case .folder, .unknown:
+            throw ConversionError.unsupported("\(source.lastPathComponent) has no conversion options.")
+        }
+    }
+
+    // MARK: - Availability
+
+    static func availability(target: Format, source: FileCategory) -> Availability {
+        if let offered = ConversionCatalog.targets[source], !offered.contains(target) {
+            return .unavailable("\(source.title) cannot become \(target.displayName).")
+        }
+        if target.requiresFFmpeg, !Toolchain.hasFFmpeg {
+            return .unavailable("Needs ffmpeg — brew install ffmpeg")
+        }
+        if target.requiresLibreOffice, !Toolchain.hasLibreOffice {
+            return .unavailable("Needs LibreOffice — brew install --cask libreoffice")
+        }
+        if !Settings.shared.useExternalTools, target.requiresFFmpeg || target.requiresLibreOffice {
+            return .unavailable("External tools are turned off in Settings.")
+        }
+        if target.category == .image, !Raster.canEncode(target) {
+            if target == .webp, WebPEncoder.isAvailable {
+                return .ok
+            }
+            return .unavailable("This Mac cannot write \(target.displayName) files.")
+        }
+        if source == .spreadsheet, !["xlsx", "ods", "csv", "tsv"].contains(target.ext), target != .pdf {
+            return .unavailable("Spreadsheets cannot become \(target.displayName).")
+        }
+        return .ok
+    }
+}
diff --git a/Sources/Konverter/Convert/DocumentConverter.swift b/Sources/Konverter/Convert/DocumentConverter.swift
new file mode 100644
index 0000000..9b2a4bc
--- /dev/null
+++ b/Sources/Konverter/Convert/DocumentConverter.swift
@@ -0,0 +1,113 @@
+import AppKit
+import Foundation
+import PDFKit
+
+/// Document conversions. `textutil` handles the Office formats; Markdown and
+/// EPUB are ours; PDF output lays text out with CoreText unless LibreOffice is
+/// available for pixel-perfect fidelity.
+enum DocumentConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try cancellation?.check()
+        let sourceExtension = FileKind.canonicalExtension(source.pathExtension)
+
+        switch format {
+        case .txt:
+            guard let text = TextDocument.plainText(from: source) else {
+                throw ConversionError.unreadable(source.lastPathComponent)
+            }
+            try TextDocument.write(text, to: destination)
+
+        case .md:
+            if sourceExtension == "md" || sourceExtension == "txt" {
+                let text = TextDocument.plainText(from: source) ?? ""
+                try TextDocument.write(text, to: destination)
+            } else {
+                let html = try TextDocument.html(from: source)
+                try TextDocument.write(Markdown.markdown(fromHTML: html), to: destination)
+            }
+
+        case .html:
+            try TextDocument.write(try TextDocument.html(from: source), to: destination)
+
+        case .pdf:
+            try makePDF(from: source, at: destination, cancellation: cancellation, progress: progress)
+
+        case .epub:
+            let title = source.deletingPathExtension().lastPathComponent
+            let html = try TextDocument.html(from: source)
+            let chapterTitle = title
+            try EbookConverter.write(
+                title: title,
+                author: "Konverter",
+                chapters: [(chapterTitle, html)],
+                at: destination
+            )
+
+        case .docx, .doc, .rtf, .odt:
+            if sourceExtension == "pdf" || sourceExtension == "epub" {
+                // No importer for these: start from extracted text/HTML.
+                let html = try TextDocument.html(from: source)
+                try TextDocument.textutilConvert(sourceHTML: html, to: format, at: destination, cancellation: cancellation)
+            } else if sourceExtension == "md" {
+                let html = try TextDocument.html(from: source)
+                try TextDocument.textutilConvert(sourceHTML: html, to: format, at: destination, cancellation: cancellation)
+            } else {
+                try TextDocument.textutilConvert(source, to: format, at: destination, cancellation: cancellation)
+            }
+
+        case .pptx, .xlsx, .ods, .pages:
+            try Office.convert(source, to: format, at: destination, cancellation: cancellation)
+
+        default:
+            throw ConversionError.unsupported("Documents cannot become \(format.displayName).")
+        }
+    }
+
+    private static func makePDF(
+        from source: URL,
+        at destination: URL,
+        cancellation: Cancellation?,
+        progress: ((Double) -> Void)?
+    ) throws {
+        let sourceExtension = FileKind.canonicalExtension(source.pathExtension)
+        if sourceExtension == "pdf" {
+            // "PDF → PDF" means a normalised, linearised copy.
+            if let document = PDFDocument(url: source) {
+                guard document.write(to: destination) else {
+                    throw ConversionError.failed("Could not rewrite the PDF.")
+                }
+                return
+            }
+        }
+
+        if Toolchain.hasLibreOffice, Settings.shared.useExternalTools {
+            do {
+                try Office.convert(source, to: .pdf, at: destination, cancellation: cancellation)
+                return
+            } catch is CancellationError {
+                throw CancellationError()
+            } catch {
+                // Fall through to the CoreText layout rather than failing the
+                // whole job because LibreOffice refused one file.
+            }
+        }
+
+        if let attributed = TextDocument.attributedString(from: source) {
+            try TextDocument.writePDF(attributed, to: destination)
+            progress?(1)
+            return
+        }
+        if let text = TextDocument.plainText(from: source), !text.isEmpty {
+            try TextDocument.writePDF(fromText: text, to: destination)
+            progress?(1)
+            return
+        }
+        throw ConversionError.failed("Could not lay out \(source.lastPathComponent) as a PDF.")
+    }
+}
diff --git a/Sources/Konverter/Convert/EbookConverter.swift b/Sources/Konverter/Convert/EbookConverter.swift
new file mode 100644
index 0000000..5c56403
--- /dev/null
+++ b/Sources/Konverter/Convert/EbookConverter.swift
@@ -0,0 +1,230 @@
+import Foundation
+
+/// EPUB in and out. Reading follows `META-INF/container.xml` → OPF → spine so
+/// chapters come out in reading order; writing produces an EPUB 3 package
+/// whose `mimetype` entry is stored uncompressed, as the spec requires.
+enum EbookConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try cancellation?.check()
+        switch format {
+        case .txt:
+            try TextDocument.write(try plainText(source), to: destination)
+        case .html:
+            try TextDocument.write(try html(source), to: destination)
+        case .md:
+            try TextDocument.write(Markdown.markdown(fromHTML: try html(source)), to: destination)
+        case .pdf:
+            try TextDocument.writePDF(fromText: try plainText(source), to: destination)
+        case .epub:
+            let title = source.deletingPathExtension().lastPathComponent
+            try write(
+                title: title,
+                author: "Konverter",
+                chapters: [(title, try html(source))],
+                at: destination
+            )
+        default:
+            throw ConversionError.unsupported("EPUB cannot become \(format.displayName).")
+        }
+        progress?(1)
+    }
+
+    // MARK: - Reading
+
+    static func plainText(_ url: URL) throws -> String {
+        let chapters = try chapters(url)
+        return chapters
+            .map { Markdown.decodeEntities(Markdown.stripTags($0.html)).trimmed }
+            .filter { !$0.isEmpty }
+            .joined(separator: "\n\n")
+    }
+
+    static func html(_ url: URL) throws -> String {
+        let chapters = try chapters(url)
+        let title = url.deletingPathExtension().lastPathComponent
+        let body = chapters.map { chapter in
+            "<section>" + (chapter.title.isEmpty ? "" : "<h2>\(Markdown.escape(chapter.title))</h2>") + chapter.body + "</section>"
+        }.joined(separator: "\n")
+        return """
+        <!DOCTYPE html><html><head><meta charset="utf-8"><title>\(Markdown.escape(title))</title>
+        <style>body{font:16px/1.6 -apple-system,Georgia,serif;max-width:720px;margin:48px auto;padding:0 24px;color:#1d1d1f}</style>
+        </head><body>\(body)</body></html>
+        """
+    }
+
+    private struct Chapter {
+        var title: String
+        var html: String
+
+        var body: String {
+            // Keep the inner markup, drop the document scaffolding.
+            var inner = html
+            if let bodyRange = inner.range(of: "(?is)<body[^>]*>", options: .regularExpression),
+               let endRange = inner.range(of: "(?is)</body>", options: .regularExpression) {
+                inner = String(inner[bodyRange.upperBound..<endRange.lowerBound])
+            }
+            return Markdown.replace(#"(?is)<(html|head|body|title|meta|link|script|style)[^>]*>|</(html|head|body|title|script|style)>"#, in: inner) { _ in "" }
+        }
+    }
+
+    private static func chapters(_ url: URL) throws -> [Chapter] {
+        let staging = try Unzip.expand(url)
+        defer { try? FileManager.default.removeItem(at: staging) }
+
+        let opf = try packageDocument(in: staging)
+        let ordered = opf.map { spineOrder(opfPath: $0, staging: staging) } ?? []
+        let files = ordered.isEmpty ? looseContentFiles(in: staging) : ordered
+
+        var chapters: [Chapter] = []
+        for file in files {
+            guard let content = try? String(contentsOf: file, encoding: .utf8) else { continue }
+            if content.trimmed.isEmpty { continue }
+            let title = Markdown.replace(#"(?is)^.*?<title[^>]*>(.*?)</title>.*$"#, in: content) { $0[1] }.trimmed
+            chapters.append(Chapter(title: title.count < 120 ? title : "", html: content))
+        }
+        guard !chapters.isEmpty else { throw ConversionError.failed("No chapters found in the EPUB.") }
+        return chapters
+    }
+
+    private static func packageDocument(in staging: URL) throws -> URL? {
+        let container = staging.appendingPathComponent("META-INF/container.xml")
+        guard let data = try? Data(contentsOf: container),
+              let text = String(data: data, encoding: .utf8),
+              let match = text.range(of: #"full-path="([^"]+)""#, options: .regularExpression) else {
+            return nil
+        }
+        let path = String(text[match]).replacingOccurrences(of: "full-path=\"", with: "").replacingOccurrences(of: "\"", with: "")
+        return staging.appendingPathComponent(path)
+    }
+
+    private static func spineOrder(opfPath: URL, staging: URL) -> [URL] {
+        guard let delegate = OPFDelegate(path: opfPath) else { return [] }
+        let parser = XMLParser(data: (try? Data(contentsOf: opfPath)) ?? Data())
+        parser.delegate = delegate
+        parser.parse()
+        let base = opfPath.deletingLastPathComponent()
+        return delegate.spine
+            .compactMap { delegate.manifest[$0] }
+            .map { base.appendingPathComponent($0) }
+            .filter { FileManager.default.fileExists(atPath: $0.path) }
+    }
+
+    private static func looseContentFiles(in staging: URL) -> [URL] {
+        let enumerator = FileManager.default.enumerator(at: staging, includingPropertiesForKeys: nil)
+        var files: [URL] = []
+        while let file = enumerator?.nextObject() as? URL {
+            let ext = file.pathExtension.lowercased()
+            if ext == "xhtml" || ext == "html" || ext == "htm" { files.append(file) }
+        }
+        return files.sorted { $0.path < $1.path }
+    }
+
+    private final class OPFDelegate: NSObject, XMLParserDelegate {
+        var manifest: [String: String] = [:]
+        var spine: [String] = []
+        private let basePath: String
+
+        init?(path: URL) {
+            basePath = path.path
+            super.init()
+        }
+
+        func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName: String?, attributes: [String: String]) {
+            switch elementName {
+            case "item":
+                if let id = attributes["id"], let href = attributes["href"] {
+                    let type = attributes["media-type"] ?? ""
+                    if type.contains("xhtml") || href.hasSuffix(".html") || href.hasSuffix(".xhtml") || href.hasSuffix(".htm") {
+                        manifest[id] = href.removingPercentEncoding ?? href
+                    }
+                }
+            case "itemref":
+                if let idref = attributes["idref"] { spine.append(idref) }
+            default:
+                break
+            }
+        }
+    }
+
+    // MARK: - Writing
+
+    static func write(
+        title: String,
+        author: String,
+        chapters: [(String, String)],
+        at destination: URL
+    ) throws {
+        guard !chapters.isEmpty else { throw ConversionError.failed("An EPUB needs at least one chapter.") }
+
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-epub-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try FileManager.default.createDirectory(at: staging.appendingPathComponent("META-INF"), withIntermediateDirectories: true)
+        try FileManager.default.createDirectory(at: staging.appendingPathComponent("OEBPS"), withIntermediateDirectories: true)
+
+        let identifier = "urn:uuid:" + UUID().uuidString.lowercased()
+        try "application/epub+zip".write(to: staging.appendingPathComponent("mimetype"), atomically: true, encoding: .utf8)
+
+        try """
+        <?xml version="1.0" encoding="UTF-8"?>
+        <container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">
+        <rootfiles><rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/></rootfiles>
+        </container>
+        """.write(to: staging.appendingPathComponent("META-INF/container.xml"), atomically: true, encoding: .utf8)
+
+        var manifest = ""
+        var spine = ""
+        var navItems = ""
+        for (index, chapter) in chapters.enumerated() {
+            let fileName = "chapter\(index + 1).xhtml"
+            let chapterTitle = chapter.0.isEmpty ? "Chapter \(index + 1)" : chapter.0
+            let body = chapter.1.contains("<body") || chapter.1.contains("<html")
+                ? chapter.1
+                : "<html xmlns=\"http://www.w3.org/1999/xhtml\"><head><title>\(Markdown.escape(chapterTitle))</title></head><body>\(chapter.1)</body></html>"
+            let xhtml = body.contains("xmlns=\"http://www.w3.org/1999/xhtml\"")
+                ? body
+                : body.replacingOccurrences(of: "<html", with: "<html xmlns=\"http://www.w3.org/1999/xhtml\"", options: [], range: body.range(of: "<html"))
+            try xhtml.write(to: staging.appendingPathComponent("OEBPS/" + fileName), atomically: true, encoding: .utf8)
+            manifest += "<item id=\"chapter\(index + 1)\" href=\"\(fileName)\" media-type=\"application/xhtml+xml\"/>\n"
+            spine += "<itemref idref=\"chapter\(index + 1)\"/>\n"
+            navItems += "<li><a href=\"\(fileName)\">\(Markdown.escape(chapterTitle))</a></li>\n"
+        }
+
+        try """
+        <?xml version="1.0" encoding="UTF-8"?>
+        <package xmlns="http://www.idpf.org/2007/opf" version="3.0" unique-identifier="bookid">
+        <metadata xmlns:dc="http://purl.org/dc/elements/1.1/">
+        <dc:identifier id="bookid">\(identifier)</dc:identifier>
+        <dc:title>\(Markdown.escape(title))</dc:title>
+        <dc:creator>\(Markdown.escape(author))</dc:creator>
+        <dc:language>en</dc:language>
+        <meta property="dcterms:modified">\(ISO8601DateFormatter().string(from: Date()))</meta>
+        </metadata>
+        <manifest>
+        \(manifest)<item id="nav" href="nav.xhtml" media-type="application/xhtml+xml" properties="nav"/>
+        </manifest>
+        <spine>
+        \(spine)</spine>
+        </package>
+        """.write(to: staging.appendingPathComponent("OEBPS/content.opf"), atomically: true, encoding: .utf8)
+
+        try """
+        <?xml version="1.0" encoding="UTF-8"?>
+        <html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
+        <head><title>\(Markdown.escape(title))</title></head>
+        <body><nav epub:type="toc" id="toc"><h1>\(Markdown.escape(title))</h1><ol>
+        \(navItems)</ol></nav></body></html>
+        """.write(to: staging.appendingPathComponent("OEBPS/nav.xhtml"), atomically: true, encoding: .utf8)
+
+        try? FileManager.default.removeItem(at: destination)
+        // mimetype must be the first entry and must not be compressed.
+        try Shell.run(Toolchain.zip, ["-X0", destination.path, "mimetype"], currentDirectory: staging)
+        try Shell.run(Toolchain.zip, ["-Xr9", destination.path, "META-INF", "OEBPS"], currentDirectory: staging)
+    }
+}
diff --git a/Sources/Konverter/Convert/FFmpeg.swift b/Sources/Konverter/Convert/FFmpeg.swift
new file mode 100644
index 0000000..80c7c8e
--- /dev/null
+++ b/Sources/Konverter/Convert/FFmpeg.swift
@@ -0,0 +1,156 @@
+import Foundation
+
+/// ffmpeg back end. Used for containers and codecs Apple's frameworks cannot
+/// write. Progress is parsed from `-progress pipe:1`.
+enum FFmpeg {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        bitrate: String = "128",
+        quality: String = "Medium",
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        guard let ffmpeg = Toolchain.ffmpeg, Settings.shared.useExternalTools else {
+            throw ConversionError.missingTool("\(format.displayName) requires ffmpeg — install it with: brew install ffmpeg")
+        }
+
+        var arguments = ["-y", "-hide_banner", "-loglevel", "error", "-i", source.path]
+        arguments += encodingArguments(for: format, bitrate: bitrate, quality: quality)
+        arguments += ["-progress", "pipe:1", "-nostats"]
+        arguments.append(destination.path)
+
+        let duration = AVConverter.duration(source) ?? 0
+        try Shell.runReportingProgress(ffmpeg, arguments, cancellation: cancellation) { _, line in
+            guard let progress, duration > 0 else { return }
+            if let range = line.range(of: "out_time_us="),
+               let microseconds = Double(line[range.upperBound...].trimmingCharacters(in: .whitespaces)) {
+                progress(min(1, microseconds / 1_000_000 / duration))
+            }
+        }
+        progress?(1)
+    }
+
+    /// Down-mixes any media to audio.
+    static func extractAudio(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        bitrate: String = "192",
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try convert(source: source, to: format, at: destination, bitrate: bitrate, cancellation: cancellation, progress: progress)
+    }
+
+    /// Progress-reporting pass-through for tools (trim, speed, gain, …).
+    static func filter(
+        source: URL,
+        at destination: URL,
+        arguments: [String],
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        guard let ffmpeg = Toolchain.ffmpeg, Settings.shared.useExternalTools else {
+            throw ConversionError.missingTool("This tool requires ffmpeg — install it with: brew install ffmpeg")
+        }
+        var full = ["-y", "-hide_banner", "-loglevel", "error", "-i", source.path]
+        full += arguments
+        full += ["-progress", "pipe:1", "-nostats", destination.path]
+
+        let duration = AVConverter.duration(source) ?? 0
+        try Shell.runReportingProgress(ffmpeg, full, cancellation: cancellation) { _, line in
+            guard let progress, duration > 0 else { return }
+            if let range = line.range(of: "out_time_us="),
+               let microseconds = Double(line[range.upperBound...].trimmingCharacters(in: .whitespaces)) {
+                progress(min(1, microseconds / 1_000_000 / duration))
+            }
+        }
+        progress?(1)
+    }
+
+    private static func encodingArguments(for format: Format, bitrate: String, quality: String) -> [String] {
+        let audioRate = "\(bitrate)k"
+        switch format {
+        case .mp3: return ["-vn", "-c:a", "libmp3lame", "-b:a", audioRate]
+        case .m4a: return ["-vn", "-c:a", "aac", "-b:a", audioRate]
+        case .wav: return ["-vn", "-c:a", "pcm_s16le"]
+        case .aiff: return ["-vn", "-c:a", "pcm_s16be"]
+        case .flac: return ["-vn", "-c:a", "flac"]
+        case .ogg: return ["-vn", "-c:a", "libvorbis", "-q:a", "5"]
+        case .opus: return ["-vn", "-c:a", "libopus", "-b:a", audioRate]
+        case .wma: return ["-vn", "-c:a", "wmav2", "-b:a", audioRate]
+        case .mkv: return videoArguments(codec: "libx264", quality: quality) + ["-c:a", "aac", "-b:a", audioRate]
+        case .webm: return ["-c:v", "libvpx-vp9", "-crf", "32", "-b:v", "0", "-c:a", "libopus", "-b:a", audioRate]
+        case .avi: return ["-c:v", "mpeg4", "-q:v", "5", "-c:a", "libmp3lame", "-b:a", audioRate]
+        case .wmv: return ["-c:v", "wmv2", "-b:v", "2M", "-c:a", "wmav2", "-b:a", audioRate]
+        case .mp4, .mov, .m4v, .gif: return videoArguments(codec: "libx264", quality: quality) + ["-c:a", "aac", "-b:a", audioRate]
+        default: return []
+        }
+    }
+
+    private static func videoArguments(codec: String, quality: String) -> [String] {
+        let crf: String
+        switch quality {
+        case "Low": crf = "30"
+        case "High": crf = "20"
+        default: crf = "25"
+        }
+        return ["-c:v", codec, "-preset", "medium", "-crf", crf, "-pix_fmt", "yuv420p"]
+    }
+}
+
+/// CoreAudio's `afconvert`: always present, handles PCM containers and
+/// channel remapping without any third-party install.
+enum CoreAudio {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil
+    ) throws {
+        guard let fileFormat = coreAudioFileFormat(for: format) else {
+            throw ConversionError.unsupported("CoreAudio cannot write \(format.displayName).")
+        }
+        do {
+            try Shell.run(
+                Toolchain.afconvert,
+                ["-f", fileFormat, "-d", dataFormat(for: fileFormat), source.path, destination.path],
+                cancellation: cancellation
+            )
+        } catch {
+            throw ConversionError.failed("CoreAudio could not convert \(source.lastPathComponent): \((error as? LocalizedError)?.errorDescription ?? error.localizedDescription)")
+        }
+    }
+
+    static func remix(
+        source: URL,
+        at destination: URL,
+        mono: Bool,
+        cancellation: Cancellation? = nil
+    ) throws {
+        try Shell.run(
+            Toolchain.afconvert,
+            ["-f", "caff", "-d", "LEI16", "-c", mono ? "1" : "2", source.path, destination.path],
+            cancellation: cancellation
+        )
+    }
+
+    private static func coreAudioFileFormat(for format: Format) -> String? {
+        switch format {
+        case .wav: return "WAVE"
+        case .aiff: return "AIFF"
+        case .m4a: return "m4af"
+        default: return nil
+        }
+    }
+
+    private static func dataFormat(for fileFormat: String) -> String {
+        switch fileFormat {
+        case "WAVE": return "LEI16"
+        case "AIFF": return "BEI16"
+        default: return "aac"
+        }
+    }
+}
diff --git a/Sources/Konverter/Convert/ImageConverter.swift b/Sources/Konverter/Convert/ImageConverter.swift
new file mode 100644
index 0000000..ee52afc
--- /dev/null
+++ b/Sources/Konverter/Convert/ImageConverter.swift
@@ -0,0 +1,328 @@
+import CoreGraphics
+import Foundation
+import ImageIO
+import AppKit
+import UniformTypeIdentifiers
+
+enum ConversionError: LocalizedError {
+    case unreadable(String)
+    case unsupported(String)
+    case failed(String)
+    case missingTool(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .unreadable(let name): return "Could not read \(name)."
+        case .unsupported(let reason): return reason
+        case .failed(let reason): return reason
+        case .missingTool(let reason): return reason
+        }
+    }
+}
+
+/// Bitmap plumbing shared by the image converter and the image tools.
+enum Raster {
+    static let encodableTypes: Set<String> = Set(
+        (CGImageDestinationCopyTypeIdentifiers() as? [String]) ?? []
+    )
+
+    static func canEncode(_ format: Format) -> Bool {
+        guard let uti = format.uti else { return false }
+        return encodableTypes.contains(uti)
+    }
+
+    static func imageSource(at url: URL) -> CGImageSource? {
+        CGImageSourceCreateWithURL(url as CFURL, [kCGImageSourceShouldCacheImmediately: true] as CFDictionary)
+    }
+
+    /// Decodes the first frame. Falls back to AppKit for formats ImageIO
+    /// cannot decode but the system can (SVG, some RAW, exotic TIFFs), and to
+    /// Quick Look as a last resort.
+    static func firstImage(at url: URL) -> CGImage? {
+        if let source = imageSource(at: url), let image = CGImageSourceCreateImageAtIndex(source, 0, nil) {
+            return image
+        }
+        if let image = NSImage(contentsOf: url),
+           let cgImage = image.cgImage(forProposedRect: nil, context: nil, hints: nil) {
+            return cgImage
+        }
+        return quickLookRaster(url)
+    }
+
+    static func frameCount(at url: URL) -> Int {
+        guard let source = imageSource(at: url) else { return 1 }
+        return max(CGImageSourceGetCount(source), 1)
+    }
+
+    private static func quickLookRaster(_ url: URL) -> CGImage? {
+        guard let qlmanage = Toolchain.qlmanage else { return nil }
+        let directory = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-ql-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: directory) }
+        try? FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+        _ = try? Shell.run(qlmanage, ["-t", "-s", "2048", "-o", directory.path, url.path])
+        guard let produced = try? FileManager.default.contentsOfDirectory(at: directory, includingPropertiesForKeys: nil)
+            .first(where: { $0.pathExtension == "png" }) else { return nil }
+        return NSImage(contentsOf: produced)?.cgImage(forProposedRect: nil, context: nil, hints: nil)
+    }
+
+    /// Paints the image onto an opaque background, dropping the alpha channel.
+    /// JPEG cannot store alpha and would otherwise render black.
+    static func flattened(_ image: CGImage, background: CGColor = CGColor(gray: 1, alpha: 1)) -> CGImage {
+        let width = image.width
+        let height = image.height
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue
+        ) else { return image }
+        context.setFillColor(background)
+        context.fill(CGRect(x: 0, y: 0, width: width, height: height))
+        context.draw(image, in: CGRect(x: 0, y: 0, width: width, height: height))
+        return context.makeImage() ?? image
+    }
+
+    /// Reduces the number of distinct colours in an image. Lossless formats
+    /// have no quality knob, so a "compress" of a PNG has to trade colour
+    /// depth for size — which is exactly what this does. `quality` is the
+    /// 0…1 slider: 1.0 leaves the pixels untouched.
+    static func posterized(_ image: CGImage, quality: Double) -> CGImage {
+        let bits = max(1.0, min(8.0, quality * 8.0))
+        let levels = min(256, max(2, Int(pow(2.0, bits))))
+        guard levels < 256 else { return image }
+
+        let width = image.width
+        let height = image.height
+        let bytesPerRow = width * 4
+        var buffer = [UInt8](repeating: 0, count: bytesPerRow * height)
+        let space = CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB()
+
+        let drawn: Bool = buffer.withUnsafeMutableBytes { raw -> Bool in
+            guard let context = CGContext(
+                data: raw.baseAddress,
+                width: width,
+                height: height,
+                bitsPerComponent: 8,
+                bytesPerRow: bytesPerRow,
+                space: space,
+                bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+            ) else { return false }
+            context.interpolationQuality = .high
+            context.draw(image, in: CGRect(x: 0, y: 0, width: width, height: height))
+            return true
+        }
+        guard drawn else { return image }
+
+        let step = 256 / levels
+        let half = step / 2
+        for index in stride(from: 0, to: buffer.count, by: 4) {
+            for channel in 0..<3 {
+                let value = Int(buffer[index + channel])
+                buffer[index + channel] = UInt8(min(255, (value / step) * step + half))
+            }
+        }
+
+        let result: CGImage? = buffer.withUnsafeMutableBytes { raw -> CGImage? in
+            guard let context = CGContext(
+                data: raw.baseAddress,
+                width: width,
+                height: height,
+                bitsPerComponent: 8,
+                bytesPerRow: bytesPerRow,
+                space: space,
+                bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+            ) else { return nil }
+            return context.makeImage()
+        }
+        return result ?? image
+    }
+
+    /// Bakes an EXIF orientation into the pixels so the result needs no
+    /// metadata to look right.
+    static func oriented(_ image: CGImage, orientation: CGImagePropertyOrientation) -> CGImage {
+        guard orientation != .up else { return image }
+        let swapsDimensions = orientation == .left || orientation == .right
+            || orientation == .leftMirrored || orientation == .rightMirrored
+        let width = swapsDimensions ? image.height : image.width
+        let height = swapsDimensions ? image.width : image.height
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: image.colorSpace ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { return image }
+
+        switch orientation {
+        case .up: break
+        case .upMirrored: context.translateBy(x: CGFloat(width), y: 0); context.scaleBy(x: -1, y: 1)
+        case .down: context.translateBy(x: CGFloat(width), y: CGFloat(height)); context.rotate(by: .pi)
+        case .downMirrored: context.translateBy(x: 0, y: CGFloat(height)); context.scaleBy(x: 1, y: -1)
+        case .left: context.translateBy(x: 0, y: CGFloat(height)); context.rotate(by: -.pi / 2)
+        case .leftMirrored: context.translateBy(x: CGFloat(width), y: CGFloat(height)); context.rotate(by: -.pi / 2); context.scaleBy(x: 1, y: -1)
+        case .right: context.translateBy(x: CGFloat(width), y: 0); context.rotate(by: .pi / 2)
+        case .rightMirrored: context.rotate(by: .pi / 2); context.scaleBy(x: 1, y: -1)
+        @unknown default: break
+        }
+        context.draw(image, in: CGRect(x: 0, y: 0, width: image.width, height: image.height))
+        return context.makeImage() ?? image
+    }
+
+    static func orientation(of source: CGImageSource) -> CGImagePropertyOrientation {
+        guard let properties = CGImageSourceCopyPropertiesAtIndex(source, 0, nil) as? [CFString: Any],
+              let raw = properties[kCGImagePropertyOrientation] as? UInt32,
+              let orientation = CGImagePropertyOrientation(rawValue: raw) else { return .up }
+        return orientation
+    }
+
+    /// Encodes a single image. `metadata == nil` writes a clean file with no
+    /// EXIF/GPS/XMP at all.
+    static func write(
+        _ image: CGImage,
+        to url: URL,
+        format: Format,
+        quality: Double,
+        metadata: [CFString: Any]?
+    ) throws {
+        guard let uti = format.uti else {
+            throw ConversionError.unsupported("\(format.displayName) is not an image format.")
+        }
+        guard canEncode(format) else {
+            throw ConversionError.unsupported("This Mac cannot write \(format.displayName) images.")
+        }
+
+        var properties: [CFString: Any] = metadata ?? [kCGImagePropertyOrientation: CGImagePropertyOrientation.up.rawValue]
+        if format.isLossy {
+            properties[kCGImageDestinationLossyCompressionQuality] = max(0, min(1, quality))
+        }
+
+        guard let destination = CGImageDestinationCreateWithURL(url as CFURL, uti as CFString, 1, nil) else {
+            throw ConversionError.failed("Could not create \(format.displayName) at \(url.lastPathComponent).")
+        }
+        CGImageDestinationAddImage(destination, image, properties as CFDictionary)
+        guard CGImageDestinationFinalize(destination) else {
+            throw ConversionError.failed("Writing \(url.lastPathComponent) failed.")
+        }
+    }
+}
+
+/// WebP has no encoder in ImageIO on macOS. `cwebp` (from libwebp) is the
+/// best path; ffmpeg works when it was built with libwebp. Both are optional.
+enum WebPEncoder {
+    static let cwebp: String? = Shell.find("cwebp", extraPaths: ["/opt/homebrew/bin", "/usr/local/bin"])
+
+    static let ffmpegHasLibwebp: Bool = {
+        guard let ffmpeg = Toolchain.ffmpeg else { return false }
+        let encoders = Shell.output(ffmpeg, ["-hide_banner", "-encoders"]) ?? ""
+        return encoders.contains("libwebp")
+    }()
+
+    static var isAvailable: Bool {
+        Settings.shared.useExternalTools && (cwebp != nil || ffmpegHasLibwebp)
+    }
+
+    static func encode(_ image: CGImage, to url: URL, quality: Double) throws {
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-webp-\(UUID().uuidString).png")
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try Raster.write(image, to: staging, format: .png, quality: 1, metadata: nil)
+
+        if let cwebp {
+            try Shell.run(cwebp, ["-quiet", "-q", String(Int(quality * 100)), staging.path, "-o", url.path])
+            return
+        }
+        if let ffmpeg = Toolchain.ffmpeg, ffmpegHasLibwebp {
+            try Shell.run(
+                ffmpeg,
+                ["-y", "-hide_banner", "-loglevel", "error", "-i", staging.path,
+                 "-frames:v", "1", "-c:v", "libwebp", "-quality", String(Int(quality * 100)), url.path]
+            )
+            return
+        }
+        throw ConversionError.unsupported("WebP needs cwebp — brew install webp")
+    }
+}
+
+/// Format → format for still and animated bitmaps.
+enum ImageConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        quality: Double = 0.9,
+        keepMetadata: Bool = true,
+        cancellation: Cancellation? = nil
+    ) throws {
+        try cancellation?.check()
+
+        if format == .pdf {
+            try PDFConverter.imageToPDF(source, at: destination, cancellation: cancellation)
+            return
+        }
+
+        // WebP has no ImageIO encoder on macOS: cwebp or ffmpeg fills in.
+        if !Raster.canEncode(format) {
+            if format == .webp, let image = Raster.firstImage(at: source), WebPEncoder.isAvailable {
+                try WebPEncoder.encode(image, to: destination, quality: quality)
+                return
+            }
+            throw ConversionError.unsupported("This Mac cannot write \(format.displayName) images.")
+        }
+
+        guard let imageSource = Raster.imageSource(at: source) else {
+            // Formats ImageIO cannot even open (SVG, PSD …): rasterise once.
+            guard let image = Raster.firstImage(at: source) else {
+                throw ConversionError.unreadable(source.lastPathComponent)
+            }
+            let prepared = format == .jpg ? Raster.flattened(image) : image
+            try Raster.write(prepared, to: destination, format: format, quality: quality, metadata: nil)
+            return
+        }
+
+        let frameCount = max(CGImageSourceGetCount(imageSource), 1)
+        guard let uti = format.uti, Raster.canEncode(format) else {
+            throw ConversionError.unsupported("This Mac cannot write \(format.displayName) images.")
+        }
+
+        var properties: [CFString: Any] = [:]
+        if keepMetadata, let sourceProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil) as? [CFString: Any] {
+            properties = sourceProperties
+        }
+        // JPEG has no alpha channel: re-encode through a white background.
+        let needsFlatten = format == .jpg
+
+        guard let destinationRef = CGImageDestinationCreateWithURL(
+            destination as CFURL,
+            uti as CFString,
+            frameCount,
+            nil
+        ) else {
+            throw ConversionError.failed("Could not create \(format.displayName) at \(destination.lastPathComponent).")
+        }
+
+        if format.isLossy {
+            properties[kCGImageDestinationLossyCompressionQuality] = quality
+        }
+
+        for index in 0..<frameCount {
+            try cancellation?.check()
+            if needsFlatten || !keepMetadata {
+                guard let frame = CGImageSourceCreateImageAtIndex(imageSource, index, nil) else { continue }
+                let prepared = needsFlatten ? Raster.flattened(frame) : frame
+                CGImageDestinationAddImage(destinationRef, prepared, properties as CFDictionary)
+            } else {
+                CGImageDestinationAddImageFromSource(destinationRef, imageSource, index, properties as CFDictionary)
+            }
+        }
+
+        guard CGImageDestinationFinalize(destinationRef) else {
+            throw ConversionError.failed("Writing \(destination.lastPathComponent) failed.")
+        }
+    }
+}
diff --git a/Sources/Konverter/Convert/ImageTools.swift b/Sources/Konverter/Convert/ImageTools.swift
new file mode 100644
index 0000000..ccfdb9e
--- /dev/null
+++ b/Sources/Konverter/Convert/ImageTools.swift
@@ -0,0 +1,268 @@
+import AppKit
+import CoreGraphics
+import CoreText
+import Foundation
+import Vision
+
+/// In-place image transforms.
+enum ImageTools {
+    static func compress(_ source: URL, at destination: URL, format: Format, quality: Double) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let outputFormat = format
+        var prepared = format == .jpg ? Raster.flattened(image) : image
+        // PNG/BMP/TIFF are lossless: ImageIO ignores the quality knob, so the
+        // slider drives colour depth instead. JPEG-style quality is meaningless
+        // there, and shipping a "compressed" file that got bigger is worse than
+        // a visibly banded one that actually got smaller.
+        switch outputFormat {
+        case .png, .bmp, .tiff:
+            prepared = Raster.posterized(prepared, quality: quality)
+        default:
+            break
+        }
+        try Raster.write(prepared, to: destination, format: outputFormat, quality: quality, metadata: nil)
+    }
+
+    static func resize(
+        _ source: URL,
+        at destination: URL,
+        maxWidth: Int,
+        maxHeight: Int,
+        percent: Int
+    ) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        var targetWidth = image.width
+        var targetHeight = image.height
+        if percent != 100 {
+            targetWidth = Int(Double(image.width) * Double(percent) / 100)
+            targetHeight = Int(Double(image.height) * Double(percent) / 100)
+        } else {
+            let scale = min(Double(maxWidth) / Double(image.width), Double(maxHeight) / Double(image.height), 1)
+            targetWidth = Int(Double(image.width) * scale)
+            targetHeight = Int(Double(image.height) * scale)
+        }
+        targetWidth = max(1, targetWidth)
+        targetHeight = max(1, targetHeight)
+        guard let resized = draw(image, size: CGSize(width: targetWidth, height: targetHeight)) else {
+            throw ConversionError.failed("Resizing failed.")
+        }
+        try write(resized, to: destination, matching: source)
+    }
+
+    static func crop(_ source: URL, at destination: URL, inset: Int, aspect: String) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        var rect = CGRect(x: 0, y: 0, width: image.width, height: image.height)
+        if aspect != "Keep", let ratio = aspectRatio(aspect) {
+            let current = CGFloat(image.width) / CGFloat(image.height)
+            if current > ratio {
+                let width = CGFloat(image.height) * ratio
+                rect = CGRect(x: (CGFloat(image.width) - width) / 2, y: 0, width: width, height: CGFloat(image.height))
+            } else {
+                let height = CGFloat(image.width) / ratio
+                rect = CGRect(x: 0, y: (CGFloat(image.height) - height) / 2, width: CGFloat(image.width), height: height)
+            }
+        }
+        if inset > 0 {
+            rect = rect.insetBy(dx: CGFloat(inset), dy: CGFloat(inset))
+        }
+        rect = rect.integral
+        guard rect.width > 1, rect.height > 1 else {
+            throw ConversionError.failed("The crop values remove the whole image.")
+        }
+        guard let cropped = image.cropping(to: rect) else {
+            throw ConversionError.failed("Cropping failed.")
+        }
+        try write(cropped, to: destination, matching: source)
+    }
+
+    private static func aspectRatio(_ aspect: String) -> CGFloat? {
+        let parts = aspect.split(separator: ":").compactMap { Double($0) }
+        guard parts.count == 2, parts[1] != 0 else { return nil }
+        return CGFloat(parts[0] / parts[1])
+    }
+
+    static func rotate(_ source: URL, at destination: URL, degrees: Int) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let radians = CGFloat(degrees) * .pi / 180
+        let swaps = degrees % 180 != 0
+        let width = swaps ? image.height : image.width
+        let height = swaps ? image.width : image.height
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: image.colorSpace ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { throw ConversionError.failed("Rotating failed.") }
+
+        context.translateBy(x: CGFloat(width) / 2, y: CGFloat(height) / 2)
+        context.rotate(by: radians)
+        context.draw(
+            image,
+            in: CGRect(
+                x: -CGFloat(image.width) / 2,
+                y: -CGFloat(image.height) / 2,
+                width: CGFloat(image.width),
+                height: CGFloat(image.height)
+            )
+        )
+        guard let rotated = context.makeImage() else { throw ConversionError.failed("Rotating failed.") }
+        try write(rotated, to: destination, matching: source)
+    }
+
+    static func flip(_ source: URL, at destination: URL, horizontal: Bool) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        guard let context = CGContext(
+            data: nil,
+            width: image.width,
+            height: image.height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: image.colorSpace ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { throw ConversionError.failed("Flipping failed.") }
+
+        if horizontal {
+            context.translateBy(x: CGFloat(image.width), y: 0)
+            context.scaleBy(x: -1, y: 1)
+        } else {
+            context.translateBy(x: 0, y: CGFloat(image.height))
+            context.scaleBy(x: 1, y: -1)
+        }
+        context.draw(image, in: CGRect(x: 0, y: 0, width: image.width, height: image.height))
+        guard let flipped = context.makeImage() else { throw ConversionError.failed("Flipping failed.") }
+        try write(flipped, to: destination, matching: source)
+    }
+
+    static func grayscale(_ source: URL, at destination: URL) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        guard let space = CGColorSpace(name: CGColorSpace.linearGray),
+              let context = CGContext(
+                data: nil,
+                width: image.width,
+                height: image.height,
+                bitsPerComponent: 8,
+                bytesPerRow: 0,
+                space: space,
+                bitmapInfo: CGImageAlphaInfo.none.rawValue
+              ) else { throw ConversionError.failed("Grayscale conversion failed.") }
+        context.draw(image, in: CGRect(x: 0, y: 0, width: image.width, height: image.height))
+        guard let gray = context.makeImage() else { throw ConversionError.failed("Grayscale conversion failed.") }
+        try write(gray, to: destination, matching: source)
+    }
+
+    static func stripMetadata(_ source: URL, at destination: URL, format: Format) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let prepared = format == .jpg ? Raster.flattened(image) : image
+        try Raster.write(prepared, to: destination, format: format, quality: 0.95, metadata: nil)
+    }
+
+    static func watermark(
+        _ source: URL,
+        at destination: URL,
+        text: String,
+        position: String,
+        opacity: Double,
+        sizePercent: Double
+    ) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let width = image.width
+        let height = image.height
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: image.colorSpace ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { throw ConversionError.failed("Watermarking failed.") }
+
+        context.draw(image, in: CGRect(x: 0, y: 0, width: width, height: height))
+
+        let fontSize = max(8, CGFloat(sizePercent) / 100 * CGFloat(width))
+        let font = NSFont.systemFont(ofSize: fontSize, weight: .semibold)
+        let attributes: [NSAttributedString.Key: Any] = [
+            .font: font,
+            .foregroundColor: NSColor.white.withAlphaComponent(opacity / 100)
+        ]
+        let attributed = NSAttributedString(string: text, attributes: attributes)
+        let line = CTLineCreateWithAttributedString(attributed)
+        let bounds = CTLineGetBoundsWithOptions(line, .useOpticalBounds)
+        let margin = fontSize * 0.6
+
+        let origin: CGPoint
+        switch position {
+        case "Bottom Left": origin = CGPoint(x: margin, y: margin)
+        case "Top Right": origin = CGPoint(x: CGFloat(width) - bounds.width - margin, y: CGFloat(height) - bounds.height - margin)
+        case "Top Left": origin = CGPoint(x: margin, y: CGFloat(height) - bounds.height - margin)
+        case "Center": origin = CGPoint(x: (CGFloat(width) - bounds.width) / 2, y: (CGFloat(height) - bounds.height) / 2)
+        default: origin = CGPoint(x: CGFloat(width) - bounds.width - margin, y: margin)
+        }
+
+        // A soft shadow keeps light text readable over light photos.
+        context.setShadow(offset: CGSize(width: 0, height: -fontSize * 0.05), blur: fontSize * 0.2, color: CGColor(gray: 0, alpha: opacity / 140))
+        context.textPosition = origin
+        CTLineDraw(line, context)
+
+        guard let stamped = context.makeImage() else { throw ConversionError.failed("Watermarking failed.") }
+        try write(stamped, to: destination, matching: source)
+    }
+
+    /// QR payloads, via Vision so it also reads the newer formats CIDetector
+    /// misses.
+    static func readQR(_ source: URL) -> String? {
+        guard let image = Raster.firstImage(at: source) else { return nil }
+        let request = VNDetectBarcodesRequest()
+        request.symbologies = [.qr, .aztec, .pdf417, .code128, .code39, .ean13, .dataMatrix]
+        let handler = VNImageRequestHandler(cgImage: image, options: [:])
+        do {
+            try handler.perform([request])
+        } catch {
+            return nil
+        }
+        let payloads = (request.results ?? []).compactMap(\.payloadStringValue)
+        return payloads.isEmpty ? nil : payloads.joined(separator: "\n")
+    }
+
+    // MARK: - Helpers
+
+    private static func draw(_ image: CGImage, size: CGSize) -> CGImage? {
+        guard let context = CGContext(
+            data: nil,
+            width: Int(size.width),
+            height: Int(size.height),
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: image.colorSpace ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { return nil }
+        context.interpolationQuality = .high
+        context.draw(image, in: CGRect(origin: .zero, size: size))
+        return context.makeImage()
+    }
+
+    private static func write(_ image: CGImage, to destination: URL, matching source: URL) throws {
+        let format = FileKind.format(of: destination) ?? FileKind.format(of: source) ?? .png
+        let prepared = format == .jpg ? Raster.flattened(image) : image
+        try Raster.write(prepared, to: destination, format: format, quality: 0.92, metadata: nil)
+    }
+}
diff --git a/Sources/Konverter/Convert/Markdown.swift b/Sources/Konverter/Convert/Markdown.swift
new file mode 100644
index 0000000..c310c2f
--- /dev/null
+++ b/Sources/Konverter/Convert/Markdown.swift
@@ -0,0 +1,282 @@
+import AppKit
+import Foundation
+
+/// A deliberately small Markdown renderer/parser. Enough for the formats the
+/// app offers (headings, emphasis, code, lists, quotes, links, rules, images)
+/// without pulling in a dependency.
+enum Markdown {
+    // MARK: - Markdown → HTML
+
+    static func html(from markdown: String, title: String = "Document") -> String {
+        let lines = markdown.replacingOccurrences(of: "\r\n", with: "\n").components(separatedBy: "\n")
+        var body: [String] = []
+        var paragraph: [String] = []
+        var listType: String?
+        var inCode = false
+        var codeLines: [String] = []
+
+        func flushParagraph() {
+            guard !paragraph.isEmpty else { return }
+            body.append("<p>" + inline(paragraph.joined(separator: " ")) + "</p>")
+            paragraph = []
+        }
+
+        func closeList() {
+            if let type = listType {
+                body.append("</\(type)>")
+                listType = nil
+            }
+        }
+
+        for rawLine in lines {
+            let line = rawLine
+            let trimmed = line.trimmingCharacters(in: .whitespaces)
+
+            if trimmed.hasPrefix("```") {
+                if inCode {
+                    body.append("<pre><code>" + escape(codeLines.joined(separator: "\n")) + "</code></pre>")
+                    codeLines = []
+                    inCode = false
+                } else {
+                    flushParagraph()
+                    closeList()
+                    inCode = true
+                }
+                continue
+            }
+            if inCode {
+                codeLines.append(line)
+                continue
+            }
+
+            if trimmed.isEmpty {
+                flushParagraph()
+                closeList()
+                continue
+            }
+
+            if let heading = headingLevel(trimmed) {
+                flushParagraph()
+                closeList()
+                let text = trimmed.dropFirst(heading).trimmingCharacters(in: .whitespaces)
+                body.append("<h\(heading)>" + inline(text) + "</h\(heading)>")
+                continue
+            }
+
+            if trimmed == "---" || trimmed == "***" || trimmed == "___" {
+                flushParagraph()
+                closeList()
+                body.append("<hr/>")
+                continue
+            }
+
+            if trimmed.hasPrefix(">") {
+                flushParagraph()
+                closeList()
+                let text = trimmed.dropFirst().trimmingCharacters(in: .whitespaces)
+                body.append("<blockquote><p>" + inline(text) + "</p></blockquote>")
+                continue
+            }
+
+            if let item = listItem(trimmed) {
+                flushParagraph()
+                if listType != item.type {
+                    closeList()
+                    listType = item.type
+                    body.append("<\(item.type)>")
+                }
+                body.append("<li>" + inline(item.text) + "</li>")
+                continue
+            }
+
+            if trimmed.hasPrefix("|") && trimmed.hasSuffix("|") {
+                flushParagraph()
+                closeList()
+                let cells = trimmed.dropFirst().dropLast().split(separator: "|").map {
+                    inline($0.trimmingCharacters(in: .whitespaces))
+                }
+                if !cells.allSatisfy({ $0.allSatisfy { $0 == "-" || $0 == ":" } }) {
+                    body.append("<tr>" + cells.map { "<td>\($0)</td>" }.joined() + "</tr>")
+                }
+                continue
+            }
+
+            paragraph.append(trimmed)
+        }
+
+        if inCode {
+            body.append("<pre><code>" + escape(codeLines.joined(separator: "\n")) + "</code></pre>")
+        }
+        flushParagraph()
+        closeList()
+
+        return """
+        <!DOCTYPE html>
+        <html><head><meta charset="utf-8"><title>\(escape(title))</title>
+        <style>
+        body { font: 16px/1.6 -apple-system, "Helvetica Neue", sans-serif; max-width: 720px; margin: 48px auto; padding: 0 24px; color: #1d1d1f; }
+        h1,h2,h3,h4 { line-height: 1.25; margin-top: 1.6em; }
+        code { background: #f2f2f4; padding: 2px 5px; border-radius: 4px; font-size: 0.9em; }
+        pre { background: #f2f2f4; padding: 14px; border-radius: 8px; overflow-x: auto; }
+        blockquote { border-left: 3px solid #d0d0d5; margin-left: 0; padding-left: 16px; color: #555; }
+        table { border-collapse: collapse; } td { border: 1px solid #ddd; padding: 6px 10px; }
+        hr { border: none; border-top: 1px solid #ddd; margin: 2em 0; }
+        </style></head><body>
+        \(body.joined(separator: "\n"))
+        </body></html>
+        """
+    }
+
+    private static func headingLevel(_ line: String) -> Int? {
+        let hashes = line.prefix { $0 == "#" }
+        guard (1...6).contains(hashes.count) else { return nil }
+        let rest = line.dropFirst(hashes.count)
+        guard rest.isEmpty || rest.first == " " else { return nil }
+        return hashes.count
+    }
+
+    private static func listItem(_ line: String) -> (type: String, text: String)? {
+        for marker in ["- ", "* ", "+ "] where line.hasPrefix(marker) {
+            return ("ul", String(line.dropFirst(2)))
+        }
+        let digits = line.prefix { $0.isNumber }
+        if !digits.isEmpty, line.dropFirst(digits.count).hasPrefix(". ") {
+            return ("ol", String(line.dropFirst(digits.count + 1)))
+        }
+        return nil
+    }
+
+    /// Inline spans: bold, italic, strikethrough, code, links, images.
+    static func inline(_ raw: String) -> String {
+        var text = escape(raw)
+        text = replace(#"!\[([^\]]*)\]\(([^)]+)\)"#, in: text) { match in
+            "<img src=\"\(match[2])\" alt=\"\(match[1])\"/>"
+        }
+        text = replace(#"\[([^\]]+)\]\(([^)]+)\)"#, in: text) { match in
+            "<a href=\"\(match[2])\">\(match[1])</a>"
+        }
+        text = replace(#"`([^`]+)`"#, in: text) { "<code>\($0[1])</code>" }
+        text = replace(#"\*\*([^*]+)\*\*"#, in: text) { "<strong>\($0[1])</strong>" }
+        text = replace(#"__([^_]+)__"#, in: text) { "<strong>\($0[1])</strong>" }
+        text = replace(#"(?<!\*)\*([^*]+)\*(?!\*)"#, in: text) { "<em>\($0[1])</em>" }
+        text = replace(#"(?<!_)_([^_]+)_(?!_)"#, in: text) { "<em>\($0[1])</em>" }
+        text = replace(#"~~([^~]+)~~"#, in: text) { "<del>\($0[1])</del>" }
+        return text
+    }
+
+    // MARK: - HTML → Markdown
+
+    static func markdown(fromHTML html: String) -> String {
+        var text = html
+        // Drop anything that cannot be represented as text.
+        text = replace(#"(?is)<(head|script|style|noscript)[^>]*>.*?</\1>"#, in: text) { _ in "" }
+        text = replace(#"(?is)<!--.*?-->"#, in: text) { _ in "" }
+
+        // Block level first.
+        for level in (1...6).reversed() {
+            text = replace(#"(?is)<h\#(level)[^>]*>(.*?)</h\#(level)>"#, in: text) { match in
+                "\n\n" + String(repeating: "#", count: level) + " " + stripTags(match[1]).trimmed + "\n\n"
+            }
+        }
+        text = replace(#"(?is)<pre[^>]*>(.*?)</pre>"#, in: text) { match in
+            "\n\n```\n" + stripTags(match[1]).trimmingCharacters(in: .newlines) + "\n```\n\n"
+        }
+        text = replace(#"(?is)<blockquote[^>]*>(.*?)</blockquote>"#, in: text) { match in
+            "\n\n" + stripTags(match[1]).trimmed
+                .split(separator: "\n").map { "> " + $0 }.joined(separator: "\n") + "\n\n"
+        }
+        text = replace(#"(?is)<li[^>]*>(.*?)</li>"#, in: text) { match in
+            "\n- " + stripTags(match[1]).trimmed
+        }
+        text = replace(#"(?is)<(ul|ol)[^>]*>"#, in: text) { _ in "\n" }
+        text = replace(#"(?is)</(ul|ol)>"#, in: text) { _ in "\n" }
+        text = replace(#"(?is)<hr[^>]*/?>"#, in: text) { _ in "\n\n---\n\n" }
+        text = replace(#"(?is)<t[dh][^>]*>(.*?)</t[dh]>"#, in: text) { match in
+            " " + stripTags(match[1]).trimmed + " |"
+        }
+        text = replace(#"(?is)<tr[^>]*>"#, in: text) { _ in "\n|" }
+        text = replace(#"(?is)<br[^>]*/?>"#, in: text) { _ in "  \n" }
+        text = replace(#"(?is)</p>"#, in: text) { _ in "\n\n" }
+        text = replace(#"(?is)<p[^>]*>"#, in: text) { _ in "\n\n" }
+        text = replace(#"(?is)</div>"#, in: text) { _ in "\n" }
+
+        // Inline.
+        text = replace(#"(?is)<(strong|b)[^>]*>(.*?)</\1>"#, in: text) { "**\(stripTags($0[2]).trimmed)**" }
+        text = replace(#"(?is)<(em|i)[^>]*>(.*?)</\1>"#, in: text) { "*\(stripTags($0[2]).trimmed)*" }
+        text = replace(#"(?is)<del[^>]*>(.*?)</del>"#, in: text) { "~~\(stripTags($0[1]).trimmed)~~" }
+        text = replace(#"(?is)<code[^>]*>(.*?)</code>"#, in: text) { "`\(stripTags($0[1]))`" }
+        text = replace(#"(?is)<img[^>]*alt=["']([^"']*)["'][^>]*src=["']([^"']+)["'][^>]*/?>"#, in: text) {
+            "![\($0[1])](\($0[2]))"
+        }
+        text = replace(#"(?is)<img[^>]*src=["']([^"']+)["'][^>]*/?>"#, in: text) { match in "![](\(match[1]))" }
+        text = replace(#"(?is)<a[^>]*href=["']([^"']+)["'][^>]*>(.*?)</a>"#, in: text) {
+            "[\(stripTags($0[2]).trimmed)](\($0[1]))"
+        }
+
+        text = stripTags(text)
+        text = decodeEntities(text)
+        // Collapse the whitespace the block replacements left behind.
+        text = replace(#"[ \t]+\n"#, in: text) { _ in "\n" }
+        text = replace(#"\n{3,}"#, in: text) { _ in "\n\n" }
+        return text.trimmingCharacters(in: .whitespacesAndNewlines) + "\n"
+    }
+
+    // MARK: - Helpers
+
+    static func escape(_ string: String) -> String {
+        string
+            .replacingOccurrences(of: "&", with: "&amp;")
+            .replacingOccurrences(of: "<", with: "&lt;")
+            .replacingOccurrences(of: ">", with: "&gt;")
+            .replacingOccurrences(of: "\"", with: "&quot;")
+    }
+
+    static func stripTags(_ html: String) -> String {
+        replace(#"(?is)<[^>]+>"#, in: html) { _ in "" }
+    }
+
+    static func decodeEntities(_ text: String) -> String {
+        var result = text
+        let map = [
+            "&nbsp;": " ", "&amp;": "&", "&lt;": "<", "&gt;": ">", "&quot;": "\"",
+            "&#39;": "'", "&apos;": "'", "&mdash;": "—", "&ndash;": "–", "&hellip;": "…",
+            "&rsquo;": "’", "&lsquo;": "‘", "&ldquo;": "“", "&rdquo;": "”"
+        ]
+        for (entity, value) in map {
+            result = result.replacingOccurrences(of: entity, with: value)
+        }
+        // Numeric entities.
+        result = replace(#"&#(\d+);"#, in: result) { match in
+            guard let code = UInt32(match[1]), let scalar = Unicode.Scalar(code) else { return match[0] }
+            return String(Character(scalar))
+        }
+        return result
+    }
+
+    /// Regex replacement where the closure receives the full match plus groups.
+    static func replace(_ pattern: String, in string: String, _ transform: ([String]) -> String) -> String {
+        guard let regex = try? NSRegularExpression(pattern: pattern) else { return string }
+        let range = NSRange(string.startIndex..., in: string)
+        let matches = regex.matches(in: string, range: range)
+        guard !matches.isEmpty else { return string }
+
+        var output = string
+        for match in matches.reversed() {
+            guard let matchRange = Range(match.range, in: output) else { continue }
+            var groups: [String] = []
+            for index in 0..<match.numberOfRanges {
+                if let groupRange = Range(match.range(at: index), in: output) {
+                    groups.append(String(output[groupRange]))
+                } else {
+                    groups.append("")
+                }
+            }
+            output.replaceSubrange(matchRange, with: transform(groups))
+        }
+        return output
+    }
+}
+
+extension String {
+    var trimmed: String { trimmingCharacters(in: .whitespacesAndNewlines) }
+}
diff --git a/Sources/Konverter/Convert/MediaTools.swift b/Sources/Konverter/Convert/MediaTools.swift
new file mode 100644
index 0000000..204e267
--- /dev/null
+++ b/Sources/Konverter/Convert/MediaTools.swift
@@ -0,0 +1,225 @@
+import AVFoundation
+import CoreMedia
+import Foundation
+
+/// Video and audio tools. Where AVFoundation cannot express an edit (loudness
+/// normalisation, silence ranges, bitrate targets) ffmpeg is used instead.
+enum MediaTools {
+    static func compressVideo(_ source: URL, at destination: URL, quality: String) throws {
+        if Toolchain.hasFFmpeg, Settings.shared.useExternalTools {
+            let crf = quality == "Low" ? "30" : (quality == "High" ? "21" : "26")
+            try FFmpeg.filter(
+                source: source,
+                at: destination,
+                arguments: ["-c:v", "libx264", "-preset", "slow", "-crf", crf, "-c:a", "aac", "-b:a", "128k"]
+            )
+            return
+        }
+        try AVConverter.convert(source: source, to: destination.pathExtension == "mov" ? .mov : .mp4, at: destination, quality: quality)
+    }
+
+    static func normalizeAudio(_ source: URL, at destination: URL) throws {
+        try FFmpeg.filter(
+            source: source,
+            at: destination,
+            arguments: ["-af", "loudnorm=I=-16:TP=-1.5:LRA=11", "-c:a", codecForContainer(destination)]
+        )
+    }
+
+    static func channels(_ source: URL, at destination: URL, mono: Bool) throws {
+        if Toolchain.hasFFmpeg, Settings.shared.useExternalTools {
+            try FFmpeg.filter(
+                source: source,
+                at: destination,
+                arguments: ["-ac", mono ? "1" : "2", "-c:a", codecForContainer(destination)]
+            )
+            return
+        }
+        try CoreAudio.remix(source: source, at: destination, mono: mono)
+    }
+
+    static func bleep(_ source: URL, at destination: URL, start: Double, end: Double) throws {
+        let filter = "volume=enable='between(t,\(start),\(end))':volume=0"
+        try FFmpeg.filter(
+            source: source,
+            at: destination,
+            arguments: ["-af", filter, "-c:a", codecForContainer(destination)]
+        )
+    }
+
+    static func compressAudio(_ source: URL, at destination: URL, bitrate: String) throws {
+        guard let format = FileKind.format(of: destination) else {
+            throw ConversionError.failed("Unknown audio container.")
+        }
+        try FFmpeg.convert(source: source, to: format, at: destination, bitrate: bitrate)
+    }
+
+    /// Audio edits keep the source container where possible so the output name
+    /// and the file itself stay recognisable.
+    static func audioSibling(for source: URL, suffix: String, forcing format: Format? = nil) -> URL {
+        let resolved = format ?? FileKind.format(of: source) ?? .m4a
+        return OutputNaming.sibling(for: source, suffix: suffix, extension: resolved.ext)
+    }
+
+    private static func codecForContainer(_ url: URL) -> String {
+        switch FileKind.canonicalExtension(url.pathExtension) {
+        case "mp3": return "libmp3lame"
+        case "ogg": return "libvorbis"
+        case "opus": return "libopus"
+        case "flac": return "flac"
+        case "wav": return "pcm_s16le"
+        case "aiff": return "pcm_s16be"
+        case "wma": return "wmav2"
+        case "caf": return "pcm_s16le"
+        default: return "aac"
+        }
+    }
+}
+
+/// Serialisable, human readable descriptions for the info tools.
+enum MediaInfo {
+    static func describe(_ url: URL) -> String {
+        switch FileKind.category(of: url) {
+        case .image: return describeImage(url)
+        case .video, .audio: return describeMedia(url)
+        case .pdf: return describePDF(url)
+        case .archive: return describeArchive(url)
+        case .spreadsheet, .document, .ebook, .subtitle: return describeText(url)
+        default: return describeFile(url)
+        }
+    }
+
+    static func describeFile(_ url: URL) -> String {
+        describeFileBasics(url).joined(separator: "\n")
+    }
+
+    private static func describeFileBasics(_ url: URL) -> [String] {
+        var lines: [String] = ["Name: \(url.lastPathComponent)"]
+        let values = try? url.resourceValues(forKeys: [.fileSizeKey, .creationDateKey, .contentModificationDateKey])
+        if let size = values?.fileSize {
+            lines.append("Size: \(ByteCountFormatter.string(fromByteCount: Int64(size), countStyle: .file))")
+        }
+        if let created = values?.creationDate {
+            lines.append("Created: \(DateFormatter.localizedString(from: created, dateStyle: .medium, timeStyle: .short))")
+        }
+        if let modified = values?.contentModificationDate {
+            lines.append("Modified: \(DateFormatter.localizedString(from: modified, dateStyle: .medium, timeStyle: .short))")
+        }
+        return lines
+    }
+
+    private static func describeImage(_ url: URL) -> String {
+        var lines = describeFileBasics(url)
+        guard let source = Raster.imageSource(at: url) else { return lines.joined(separator: "\n") }
+        let properties = CGImageSourceCopyPropertiesAtIndex(source, 0, nil) as? [CFString: Any] ?? [:]
+        if let width = properties[kCGImagePropertyPixelWidth] as? Int,
+           let height = properties[kCGImagePropertyPixelHeight] as? Int {
+            lines.append("Dimensions: \(width) × \(height)")
+        }
+        if let dpiWidth = properties[kCGImagePropertyDPIWidth] as? Double {
+            lines.append("Resolution: \(Int(dpiWidth)) dpi")
+        }
+        if let colorModel = properties[kCGImagePropertyColorModel] as? String {
+            lines.append("Color: \(colorModel)")
+        }
+        if properties[kCGImagePropertyGIFDictionary] != nil {
+            lines.append("Format: animated GIF")
+        }
+        if let exif = properties[kCGImagePropertyExifDictionary] as? [CFString: Any] {
+            if let date = exif[kCGImagePropertyExifDateTimeOriginal] as? String {
+                lines.append("Captured: \(date)")
+            }
+        }
+        if let tiff = properties[kCGImagePropertyTIFFDictionary] as? [CFString: Any] {
+            if let make = tiff[kCGImagePropertyTIFFMake] as? String,
+               let model = tiff[kCGImagePropertyTIFFModel] as? String {
+                lines.append("Camera: \(make) \(model)")
+            }
+        }
+        if let gps = properties[kCGImagePropertyGPSDictionary] as? [CFString: Any],
+           let latitude = gps[kCGImagePropertyGPSLatitude] as? Double,
+           let longitude = gps[kCGImagePropertyGPSLongitude] as? Double {
+            lines.append("Location: \(String(format: "%.4f", latitude)), \(String(format: "%.4f", longitude))")
+        }
+        lines.append("Frames: \(Raster.frameCount(at: url))")
+        return lines.joined(separator: "\n")
+    }
+
+    private static func describeMedia(_ url: URL) -> String {
+        var lines = describeFileBasics(url)
+        let asset = AVURLAsset(url: url)
+        let duration = CMTimeGetSeconds(asset.duration)
+        if duration.isFinite, duration > 0 {
+            let minutes = Int(duration) / 60
+            let remaining = duration - Double(minutes * 60)
+            lines.append("Duration: \(minutes):\(String(format: "%05.2f", remaining))")
+        }
+        for track in asset.tracks {
+            switch track.mediaType {
+            case .video:
+                let size = track.naturalSize.applying(track.preferredTransform)
+                let frameRate = track.nominalFrameRate
+                lines.append("Video: \(Int(abs(size.width)))×\(Int(abs(size.height))) @ \(String(format: "%.2f", frameRate)) fps")
+                lines.append("Codec: \(codecName(track) ?? "unknown")")
+            case .audio:
+                let rate = track.nominalFrameRate
+                lines.append("Audio: \(codecName(track) ?? "unknown") @ \(Int(rate)) Hz")
+            default:
+                break
+            }
+        }
+        if let ffprobe = Toolchain.ffprobe,
+           let output = Shell.output(ffprobe, ["-v", "error", "-show_entries", "format=bit_rate:stream=bit_rate", "-of", "default=nw=1", url.path]) {
+            let rates = output.split(separator: "\n").compactMap { $0.split(separator: "=").last }.compactMap { Int($0) }.filter { $0 > 0 }
+            if let bitrate = rates.first {
+                lines.append("Bitrate: \(bitrate / 1000) kbps")
+            }
+        }
+        return lines.joined(separator: "\n")
+    }
+
+    private static func codecName(_ track: AVAssetTrack) -> String? {
+        guard let raw = track.formatDescriptions.first else { return nil }
+        let description = raw as! CMFormatDescription
+        return describeFormat(description)
+    }
+
+    private static func describeFormat(_ description: CMFormatDescription) -> String? {
+        let codec = CMFormatDescriptionGetMediaSubType(description)
+        let bytes = [
+            UInt8((codec >> 24) & 0xFF), UInt8((codec >> 16) & 0xFF),
+            UInt8((codec >> 8) & 0xFF), UInt8(codec & 0xFF)
+        ]
+        let name = String(bytes: bytes, encoding: .ascii)?.trimmingCharacters(in: .whitespaces)
+        return name?.isEmpty == false ? name : nil
+    }
+
+    private static func describePDF(_ url: URL) -> String {
+        var lines = describeFileBasics(url)
+        lines.append("Pages: \(PDFConverter.pageCount(url))")
+        if let size = PDFConverter.pageSize(url) {
+            lines.append("Page size: \(Int(size.width)) × \(Int(size.height)) pt")
+        }
+        let text = PDFConverter.extractText(url)
+        lines.append("Words: \(text.split { $0 == " " || $0.isNewline }.count)")
+        return lines.joined(separator: "\n")
+    }
+
+    private static func describeArchive(_ url: URL) -> String {
+        var lines = describeFileBasics(url)
+        let listing = (try? ArchiveConverter.list(url)) ?? ""
+        let entries = listing.split(separator: "\n").count
+        lines.append("Entries: \(entries)")
+        return lines.joined(separator: "\n")
+    }
+
+    private static func describeText(_ url: URL) -> String {
+        var lines = describeFileBasics(url)
+        let text = TextDocument.plainText(from: url) ?? ""
+        let words = text.split { $0 == " " || $0.isNewline }.count
+        lines.append("Words: \(words)")
+        lines.append("Characters: \(text.count)")
+        lines.append("Lines: \(text.components(separatedBy: "\n").count)")
+        return lines.joined(separator: "\n")
+    }
+}
diff --git a/Sources/Konverter/Convert/Office.swift b/Sources/Konverter/Convert/Office.swift
new file mode 100644
index 0000000..292cfab
--- /dev/null
+++ b/Sources/Konverter/Convert/Office.swift
@@ -0,0 +1,110 @@
+import Foundation
+
+/// LibreOffice bridge for formats Apple's frameworks cannot render (PPT/PPTX,
+/// XLS/XLSX/ODS when they need layout, PAGES, Keynote).
+enum Office {
+    /// LibreOffice cannot run two headless conversions at once in the same
+    /// profile, so every call is serialised.
+    private static let lock = NSLock()
+
+    static func convert(
+        _ source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil
+    ) throws {
+        guard let soffice = Toolchain.soffice, Settings.shared.useExternalTools else {
+            throw ConversionError.missingTool(
+                "\(format.displayName) needs LibreOffice. Install it with: brew install --cask libreoffice"
+            )
+        }
+        let filter = filterName(for: format)
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-office-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+
+        lock.lock()
+        defer { lock.unlock() }
+        try cancellation?.check()
+
+        try Shell.run(
+            soffice,
+            [
+                "--headless", "--norestore", "--nolockcheck", "--nodefault",
+                "-env:UserInstallation=file://" + staging.path + "/profile",
+                "--convert-to", filter,
+                "--outdir", staging.path,
+                source.path
+            ],
+            cancellation: cancellation
+        )
+
+        let produced = try FileManager.default
+            .contentsOfDirectory(at: staging, includingPropertiesForKeys: nil)
+            .first { $0.pathExtension.lowercased() == destination.pathExtension.lowercased() }
+        guard let produced else {
+            throw ConversionError.failed("LibreOffice did not produce a \(format.displayName) file.")
+        }
+        try? FileManager.default.removeItem(at: destination)
+        try FileManager.default.moveItem(at: produced, to: destination)
+    }
+
+    static func filterName(for format: Format) -> String {
+        switch format {
+        case .pdf: return "pdf"
+        case .docx: return "docx"
+        case .odt: return "odt"
+        case .rtf: return "rtf"
+        case .txt: return "txt"
+        case .html: return "html"
+        case .csv: return "csv"
+        case .xlsx: return "xlsx"
+        case .ods: return "ods"
+        case .pptx: return "pptx"
+        case .epub: return "epub"
+        case .png: return "png"
+        case .jpg: return "jpg"
+        default: return format.ext
+        }
+    }
+}
+
+/// PPT/PPTX/KEY → PDF or images. Everything funnels through a PDF so multi
+/// slide decks come out with one image per slide.
+enum SlidesConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        switch format {
+        case .pdf:
+            try Office.convert(source, to: .pdf, at: destination, cancellation: cancellation)
+        case .png, .jpg:
+            let staging = FileManager.default.temporaryDirectory
+                .appendingPathComponent("konverter-slides-\(UUID().uuidString)", isDirectory: true)
+            defer { try? FileManager.default.removeItem(at: staging) }
+            try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+            let pdf = staging.appendingPathComponent("deck.pdf")
+            try Office.convert(source, to: .pdf, at: pdf, cancellation: cancellation)
+            let directory = OutputNaming.artifactDirectory(
+                for: destination,
+                suffix: ""
+            )
+            try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+            _ = try PDFConverter.renderPages(
+                pdf,
+                to: format,
+                into: directory,
+                dpi: 200,
+                cancellation: cancellation,
+                progress: progress
+            )
+        default:
+            throw ConversionError.unsupported("Slides become PDF or images.")
+        }
+    }
+}
diff --git a/Sources/Konverter/Convert/PDFConverter.swift b/Sources/Konverter/Convert/PDFConverter.swift
new file mode 100644
index 0000000..9935c10
--- /dev/null
+++ b/Sources/Konverter/Convert/PDFConverter.swift
@@ -0,0 +1,381 @@
+import AppKit
+import CoreGraphics
+import CoreText
+import Foundation
+import PDFKit
+
+/// Everything PDF: rasterising pages, building PDFs from images, text
+/// extraction, splitting, merging, rotating and password handling.
+enum PDFConverter {
+    static let defaultDPI: CGFloat = 300
+
+    // MARK: - Images → PDF
+
+    static func imageToPDF(_ source: URL, at destination: URL, cancellation: Cancellation? = nil) throws {
+        guard let image = Raster.firstImage(at: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        try imagesToPDF([(image, nil)], at: destination, cancellation: cancellation)
+    }
+
+    /// Each image becomes one page, sized so the image keeps its aspect ratio
+    /// at 72 dpi (a 1440×900 screenshot becomes a 1440×900 pt page).
+    static func imagesToPDF(
+        _ pages: [(image: CGImage, name: String?)],
+        at destination: URL,
+        pageSize: CGSize? = nil,
+        cancellation: Cancellation? = nil
+    ) throws {
+        guard !pages.isEmpty else { throw ConversionError.failed("Nothing to put in the PDF.") }
+
+        var mediaBox = CGRect(origin: .zero, size: pages[0].name == nil
+            ? CGSize(width: pages[0].image.width, height: pages[0].image.height)
+            : CGSize(width: 595, height: 842))
+        if let pageSize { mediaBox = CGRect(origin: .zero, size: pageSize) }
+
+        guard let context = CGContext(destination as CFURL, mediaBox: &mediaBox, nil) else {
+            throw ConversionError.failed("Could not create \(destination.lastPathComponent).")
+        }
+
+        for page in pages {
+            try cancellation?.check()
+            let image = page.image
+            var box = mediaBox
+            if page.name == nil || pageSize == nil {
+                box = CGRect(x: 0, y: 0, width: image.width, height: image.height)
+            }
+            context.beginPDFPage([kCGPDFContextMediaBox: CGRectToData(box)] as CFDictionary)
+
+            let scale = min(box.width / CGFloat(image.width), box.height / CGFloat(image.height))
+            let size = CGSize(width: CGFloat(image.width) * scale, height: CGFloat(image.height) * scale)
+            let rect = CGRect(
+                x: (box.width - size.width) / 2,
+                y: (box.height - size.height) / 2,
+                width: size.width,
+                height: size.height
+            )
+            context.draw(image, in: rect)
+            context.endPDFPage()
+        }
+        context.closePDF()
+    }
+
+    private static func CGRectToData(_ rect: CGRect) -> CFData {
+        var rect = rect
+        return CFDataCreate(nil, withUnsafeBytes(of: &rect) { $0.bindMemory(to: UInt8.self).baseAddress }, MemoryLayout<CGRect>.size)
+    }
+
+    // MARK: - PDF → images
+
+    /// Renders each page to `format` at `dpi`. Returns the files written.
+    @discardableResult
+    static func renderPages(
+        _ source: URL,
+        to format: Format,
+        into directory: URL,
+        dpi: CGFloat = 300,
+        pageNumbers: [Int]? = nil,
+        quality: Double = 0.85,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws -> [URL] {
+        guard let document = PDFDocument(url: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let base = source.deletingPathExtension().lastPathComponent
+        try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+
+        let indices = pageNumbers ?? Array(0..<document.pageCount)
+        var written: [URL] = []
+        let scale = dpi / 72
+        let padding = String(indices.count).count
+
+        for (offset, pageIndex) in indices.enumerated() {
+            try cancellation?.check()
+            guard let page = document.page(at: pageIndex) else { continue }
+            let bounds = page.bounds(for: .mediaBox)
+            let pixelWidth = Int((bounds.width * scale).rounded())
+            let pixelHeight = Int((bounds.height * scale).rounded())
+            guard pixelWidth > 0, pixelHeight > 0 else { continue }
+
+            guard let context = CGContext(
+                data: nil,
+                width: pixelWidth,
+                height: pixelHeight,
+                bitsPerComponent: 8,
+                bytesPerRow: 0,
+                space: CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB(),
+                bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue
+            ) else { continue }
+
+            context.setFillColor(CGColor(gray: 1, alpha: 1))
+            context.fill(CGRect(x: 0, y: 0, width: pixelWidth, height: pixelHeight))
+            context.scaleBy(x: scale, y: scale)
+            context.translateBy(x: -bounds.origin.x, y: -bounds.origin.y)
+            page.draw(with: .mediaBox, to: context)
+
+            guard let image = context.makeImage() else { continue }
+            let number = String(pageIndex + 1).leftPadded(to: padding)
+            let target = OutputNaming.availableURL(
+                for: directory.appendingPathComponent("\(base)-\(number)").appendingPathExtension(format.ext)
+            )
+            try Raster.write(image, to: target, format: format, quality: quality, metadata: nil)
+            written.append(target)
+            progress?(Double(offset + 1) / Double(indices.count))
+        }
+        return written
+    }
+
+    // MARK: - Text
+
+    static func extractText(_ source: URL, pageBreak: String = "\n\n") -> String {
+        guard let document = PDFDocument(url: source) else { return "" }
+        return (0..<document.pageCount)
+            .compactMap { document.page(at: $0)?.string }
+            .joined(separator: pageBreak)
+    }
+
+    // MARK: - Document surgery
+
+    static func merge(_ sources: [URL], at destination: URL, cancellation: Cancellation? = nil) throws {
+        let merged = PDFDocument()
+        var index = 0
+        for source in sources {
+            try cancellation?.check()
+            guard let document = PDFDocument(url: source) else {
+                throw ConversionError.unreadable(source.lastPathComponent)
+            }
+            for pageIndex in 0..<document.pageCount {
+                try cancellation?.check()
+                guard let page = document.page(at: pageIndex)?.copy() as? PDFPage else { continue }
+                merged.insert(page, at: index)
+                index += 1
+            }
+        }
+        guard merged.pageCount > 0 else { throw ConversionError.failed("No pages to merge.") }
+        guard merged.write(to: destination) else {
+            throw ConversionError.failed("Could not write \(destination.lastPathComponent).")
+        }
+    }
+
+    /// Splits into chunks of `pagesPerFile`, writing into a sibling folder.
+    static func split(
+        _ source: URL,
+        pagesPerFile: Int,
+        into directory: URL,
+        cancellation: Cancellation? = nil
+    ) throws -> [URL] {
+        guard let document = PDFDocument(url: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let base = source.deletingPathExtension().lastPathComponent
+        try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+
+        var written: [URL] = []
+        var start = 0
+        var part = 1
+        while start < document.pageCount {
+            try cancellation?.check()
+            let chunk = PDFDocument()
+            var cursor = 0
+            for pageIndex in start..<min(start + pagesPerFile, document.pageCount) {
+                guard let page = document.page(at: pageIndex)?.copy() as? PDFPage else { continue }
+                chunk.insert(page, at: cursor)
+                cursor += 1
+            }
+            let target = OutputNaming.availableURL(
+                for: directory.appendingPathComponent("\(base)-\(String(format: "%02d", part)).pdf")
+            )
+            guard chunk.write(to: target) else {
+                throw ConversionError.failed("Could not write \(target.lastPathComponent).")
+            }
+            written.append(target)
+            start += pagesPerFile
+            part += 1
+        }
+        return written
+    }
+
+    static func rotate(_ source: URL, degrees: Int, at destination: URL) throws {
+        guard let document = PDFDocument(url: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        for index in 0..<document.pageCount {
+            guard let page = document.page(at: index) else { continue }
+            page.rotation = (page.rotation + degrees) % 360
+        }
+        guard document.write(to: destination) else {
+            throw ConversionError.failed("Could not write \(destination.lastPathComponent).")
+        }
+    }
+
+    static func encrypt(_ source: URL, at destination: URL, password: String, ownerPassword: String?) throws {
+        guard let document = PDFDocument(url: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        let options: [PDFDocumentWriteOption: Any] = [
+            .userPasswordOption: password,
+            .ownerPasswordOption: ownerPassword?.isEmpty == false ? ownerPassword! : password
+        ]
+        guard document.write(to: destination, withOptions: options) else {
+            throw ConversionError.failed("Could not write the encrypted PDF.")
+        }
+    }
+
+    /// Rewrites through an image pipeline, which is what "compress a PDF"
+    /// means in practice: re-encode each page as a JPEG at lower quality.
+    static func compress(
+        _ source: URL,
+        at destination: URL,
+        quality: Double,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        guard let document = PDFDocument(url: source) else {
+            throw ConversionError.unreadable(source.lastPathComponent)
+        }
+        guard let firstPage = document.page(at: 0) else { return }
+        var mediaBox = firstPage.bounds(for: .mediaBox)
+        guard let context = CGContext(destination as CFURL, mediaBox: &mediaBox, nil) else {
+            throw ConversionError.failed("Could not create the compressed PDF.")
+        }
+        for index in 0..<document.pageCount {
+            try cancellation?.check()
+            guard let page = document.page(at: index) else { continue }
+            let bounds = page.bounds(for: .mediaBox)
+            let scale: CGFloat = 150 / 72
+            let width = Int(bounds.width * scale)
+            let height = Int(bounds.height * scale)
+            var box = bounds
+            context.beginPDFPage([kCGPDFContextMediaBox: CGRectToData(box)] as CFDictionary)
+            if width > 0, height > 0,
+               let bitmap = CGContext(
+                data: nil,
+                width: width,
+                height: height,
+                bitsPerComponent: 8,
+                bytesPerRow: 0,
+                space: CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB(),
+                bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue
+               ) {
+                bitmap.setFillColor(CGColor(gray: 1, alpha: 1))
+                bitmap.fill(CGRect(x: 0, y: 0, width: width, height: height))
+                bitmap.scaleBy(x: scale, y: scale)
+                bitmap.translateBy(x: -bounds.origin.x, y: -bounds.origin.y)
+                page.draw(with: .mediaBox, to: bitmap)
+                if let image = bitmap.makeImage(),
+                   let jpeg = JPEGEncoder.encode(image, quality: quality) {
+                    box = bounds
+                    context.draw(jpeg, in: bounds)
+                }
+            }
+            context.endPDFPage()
+            progress?(Double(index + 1) / Double(document.pageCount))
+        }
+        context.closePDF()
+    }
+
+    /// Lays images out in a grid on a single page (Tangerine's "collage").
+    static func collage(
+        _ entries: [(image: CGImage, name: String)],
+        at destination: URL,
+        columns: Int,
+        page: String,
+        margin: CGFloat,
+        captions: Bool,
+        cancellation: Cancellation? = nil
+    ) throws {
+        guard !entries.isEmpty else { throw ConversionError.failed("Nothing to lay out.") }
+        let pageSize: CGSize
+        switch page {
+        case "Letter": pageSize = CGSize(width: 612, height: 792)
+        case "Square": pageSize = CGSize(width: 800, height: 800)
+        default: pageSize = CGSize(width: 595, height: 842)
+        }
+        var mediaBox = CGRect(origin: .zero, size: pageSize)
+        guard let context = CGContext(destination as CFURL, mediaBox: &mediaBox, nil) else {
+            throw ConversionError.failed("Could not create \(destination.lastPathComponent).")
+        }
+        context.beginPDFPage([kCGPDFContextMediaBox: CGRectToData(mediaBox)] as CFDictionary)
+
+        let columnCount = max(1, columns)
+        let rowCount = Int(ceil(Double(entries.count) / Double(columnCount)))
+        let usableWidth = pageSize.width - margin * 2
+        let usableHeight = pageSize.height - margin * 2
+        let cellWidth = usableWidth / CGFloat(columnCount)
+        let cellHeight = usableHeight / CGFloat(max(1, rowCount))
+        let captionHeight: CGFloat = captions ? 14 : 0
+
+        for (index, entry) in entries.enumerated() {
+            try cancellation?.check()
+            let column = index % columnCount
+            let row = index / columnCount
+            let cell = CGRect(
+                x: margin + CGFloat(column) * cellWidth,
+                y: pageSize.height - margin - CGFloat(row + 1) * cellHeight,
+                width: cellWidth,
+                height: cellHeight
+            ).insetBy(dx: 6, dy: 6)
+
+            let imageArea = cell.insetBy(dx: 0, dy: captionHeight)
+            let scale = min(imageArea.width / CGFloat(entry.image.width), imageArea.height / CGFloat(entry.image.height))
+            let size = CGSize(width: CGFloat(entry.image.width) * scale, height: CGFloat(entry.image.height) * scale)
+            context.draw(entry.image, in: CGRect(
+                x: imageArea.midX - size.width / 2,
+                y: imageArea.midY - size.height / 2,
+                width: size.width,
+                height: size.height
+            ))
+
+            if captions, let escaped = entry.name as CFString? {
+                let font = CTFontCreateWithName("Helvetica" as CFString, 9, nil)
+                let attributes: [NSAttributedString.Key: Any] = [
+                    .font: font,
+                    .foregroundColor: CGColor(gray: 0.35, alpha: 1)
+                ]
+                let line = CTLineCreateWithAttributedString(
+                    NSAttributedString(string: escaped as String, attributes: attributes)
+                )
+                context.textPosition = CGPoint(x: cell.minX, y: cell.minY)
+                CTLineDraw(line, context)
+            }
+        }
+        context.endPDFPage()
+        context.closePDF()
+    }
+
+    /// Rasterises a PDF page range to a single contact sheet, used by the
+    /// "Info" summary.
+    static func pageSize(_ source: URL) -> CGSize? {
+        PDFDocument(url: source)?.page(at: 0)?.bounds(for: .mediaBox).size
+    }
+
+    static func pageCount(_ source: URL) -> Int {
+        PDFDocument(url: source)?.pageCount ?? 0
+    }
+}
+
+/// Small helper so the PDF compressor can produce JPEG bytes in memory.
+enum JPEGEncoder {
+    static func encode(_ image: CGImage, quality: Double) -> CGImage? {
+        let flattened = Raster.flattened(image)
+        guard let data = CFDataCreateMutable(nil, 0),
+              let destination = CGImageDestinationCreateWithData(data, "public.jpeg" as CFString, 1, nil) else {
+            return nil
+        }
+        CGImageDestinationAddImage(
+            destination,
+            flattened,
+            [kCGImageDestinationLossyCompressionQuality: quality] as CFDictionary
+        )
+        guard CGImageDestinationFinalize(destination) else { return nil }
+        guard let source = CGImageSourceCreateWithData(data, nil) else { return nil }
+        return CGImageSourceCreateImageAtIndex(source, 0, nil)
+    }
+}
+
+extension String {
+    func leftPadded(to width: Int, with character: Character = "0") -> String {
+        count >= width ? self : String(repeating: String(character), count: width - count) + self
+    }
+}
diff --git a/Sources/Konverter/Convert/SpreadsheetConverter.swift b/Sources/Konverter/Convert/SpreadsheetConverter.swift
new file mode 100644
index 0000000..3e8e3a0
--- /dev/null
+++ b/Sources/Konverter/Convert/SpreadsheetConverter.swift
@@ -0,0 +1,495 @@
+import AppKit
+import Foundation
+
+/// CSV/TSV/XLSX/ODS. The delimited formats are parsed in-process; XLSX is read
+/// and written as OOXML by hand so no dependency is needed; everything else
+/// goes through LibreOffice.
+enum SpreadsheetConverter {
+    typealias Rows = [[String]]
+
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws {
+        try cancellation?.check()
+        switch format {
+        case .csv, .tsv:
+            let rows = try read(source, cancellation: cancellation)
+            try write(rows, to: destination, delimiter: format == .tsv ? "\t" : ",")
+        case .xlsx:
+            let rows = try read(source, cancellation: cancellation)
+            try XLSX.write(rows, to: destination)
+        case .pdf:
+            let rows = try read(source, cancellation: cancellation)
+            try writePDF(rows, at: destination)
+        case .ods, .numbers, .xls:
+            try Office.convert(source, to: format, at: destination, cancellation: cancellation)
+        default:
+            throw ConversionError.unsupported("Spreadsheets cannot become \(format.displayName).")
+        }
+        progress?(1)
+    }
+
+    // MARK: - Reading
+
+    static func read(_ url: URL, cancellation: Cancellation? = nil) throws -> Rows {
+        switch FileKind.canonicalExtension(url.pathExtension) {
+        case "csv":
+            let text = try string(from: url)
+            return parseDelimited(text, delimiter: ",")
+        case "tsv":
+            let text = try string(from: url)
+            return parseDelimited(text, delimiter: "\t")
+        case "xlsx":
+            return try XLSX.read(url, cancellation: cancellation)
+        case "ods":
+            return try ODS.read(url, cancellation: cancellation)
+        case "pdf":
+            // Tables in a PDF: best effort, one row per line.
+            let text = PDFConverter.extractText(url)
+            return text
+                .components(separatedBy: "\n")
+                .filter { !$0.trimmed.isEmpty }
+                .map { [$0] }
+        default:
+            throw ConversionError.unsupported("Konverter cannot read .\(url.pathExtension) spreadsheets without LibreOffice.")
+        }
+    }
+
+    private static func string(from url: URL) throws -> String {
+        if let utf8 = try? String(contentsOf: url, encoding: .utf8) { return utf8 }
+        if let latin = try? String(contentsOf: url, encoding: .isoLatin1) { return latin }
+        throw ConversionError.unreadable(url.lastPathComponent)
+    }
+
+    /// RFC 4180-ish: quotes, doubled quotes, embedded newlines.
+    static func parseDelimited(_ text: String, delimiter: Character) -> Rows {
+        var rows: Rows = []
+        var row: [String] = []
+        var field = ""
+        var inQuotes = false
+        var iterator = text.makeIterator()
+        var pending: Character?
+
+        while let character = pending ?? iterator.next() {
+            pending = nil
+            if inQuotes {
+                if character == "\"" {
+                    if let next = iterator.next() {
+                        if next == "\"" {
+                            field.append("\"")
+                        } else {
+                            inQuotes = false
+                            pending = next
+                        }
+                    } else {
+                        inQuotes = false
+                    }
+                } else {
+                    field.append(character)
+                }
+                continue
+            }
+            switch character {
+            case "\"":
+                inQuotes = true
+            case delimiter:
+                row.append(field)
+                field = ""
+            case "\r":
+                break
+            case "\n":
+                row.append(field)
+                field = ""
+                rows.append(row)
+                row = []
+            default:
+                field.append(character)
+            }
+        }
+        if !field.isEmpty || !row.isEmpty {
+            row.append(field)
+            rows.append(row)
+        }
+        // Drop a trailing empty row caused by a final newline.
+        if let last = rows.last, last.allSatisfy({ $0.isEmpty }) { rows.removeLast() }
+        return rows
+    }
+
+    // MARK: - Writing
+
+    static func write(_ rows: Rows, to url: URL, delimiter: String) throws {
+        let text = rows.map { row in
+            row.map { escape($0, delimiter: delimiter) }.joined(separator: delimiter)
+        }.joined(separator: "\n")
+        try text.write(to: url, atomically: true, encoding: .utf8)
+    }
+
+    private static func escape(_ field: String, delimiter: String) -> String {
+        let needsQuotes = field.contains(delimiter) || field.contains("\"") || field.contains("\n") || field.contains("\r")
+        guard needsQuotes else { return field }
+        return "\"" + field.replacingOccurrences(of: "\"", with: "\"\"") + "\""
+    }
+
+    static func writePDF(_ rows: Rows, at url: URL) throws {
+        let columnCount = rows.map(\.count).max() ?? 0
+        guard columnCount > 0 else { throw ConversionError.failed("Nothing to write.") }
+        var html = """
+        <!DOCTYPE html><html><head><meta charset="utf-8"><style>
+        body{font:11px -apple-system,sans-serif;margin:24px}
+        table{border-collapse:collapse;width:100%}
+        td,th{border:1px solid #d8d8dd;padding:4px 8px;vertical-align:top}
+        th{background:#f4f4f7;text-align:left}
+        </style></head><body><table>
+        """
+        for (index, row) in rows.enumerated() {
+            let tag = index == 0 ? "th" : "td"
+            html += "<tr>" + (0..<columnCount).map { column in
+                let value = column < row.count ? row[column] : ""
+                return "<\(tag)>\(Markdown.escape(value))</\(tag)>"
+            }.joined() + "</tr>"
+        }
+        html += "</table></body></html>"
+        let attributed = try? NSAttributedString(
+            data: Data(html.utf8),
+            options: [.documentType: NSAttributedString.DocumentType.html],
+            documentAttributes: nil
+        )
+        if let attributed {
+            try TextDocument.writePDF(attributed, to: url, pageSize: CGSize(width: 842, height: 595))
+        } else {
+            try TextDocument.writePDF(fromText: rows.map { $0.joined(separator: "\t") }.joined(separator: "\n"), to: url)
+        }
+    }
+}
+
+/// Minimal OOXML spreadsheet reader/writer.
+enum XLSX {
+    static func read(_ url: URL, cancellation: Cancellation? = nil) throws -> SpreadsheetConverter.Rows {
+        let staging = try Unzip.expand(url, cancellation: cancellation)
+        defer { try? FileManager.default.removeItem(at: staging) }
+
+        let sharedStrings = parseSharedStrings(
+            at: staging.appendingPathComponent("xl/sharedStrings.xml")
+        )
+        let sheetURL = firstSheet(at: staging)
+        guard let sheetURL else { throw ConversionError.failed("This workbook has no sheets.") }
+        return try parseSheet(at: sheetURL, sharedStrings: sharedStrings)
+    }
+
+    static func write(_ rows: SpreadsheetConverter.Rows, to url: URL) throws {
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-xlsx-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        try FileManager.default.createDirectory(
+            at: staging.appendingPathComponent("xl/_rels"),
+            withIntermediateDirectories: true
+        )
+        try FileManager.default.createDirectory(
+            at: staging.appendingPathComponent("_rels"),
+            withIntermediateDirectories: true
+        )
+        try FileManager.default.createDirectory(
+            at: staging.appendingPathComponent("xl/worksheets"),
+            withIntermediateDirectories: true
+        )
+
+        try contentTypes.write(to: staging.appendingPathComponent("[Content_Types].xml"), atomically: true, encoding: .utf8)
+        try packageRels.write(to: staging.appendingPathComponent("_rels/.rels"), atomically: true, encoding: .utf8)
+        try workbookRels.write(to: staging.appendingPathComponent("xl/_rels/workbook.xml.rels"), atomically: true, encoding: .utf8)
+        try styles.write(to: staging.appendingPathComponent("xl/styles.xml"), atomically: true, encoding: .utf8)
+        try workbook.write(to: staging.appendingPathComponent("xl/workbook.xml"), atomically: true, encoding: .utf8)
+        try sheetXML(rows).write(to: staging.appendingPathComponent("xl/worksheets/sheet1.xml"), atomically: true, encoding: .utf8)
+
+        let zip = Toolchain.zip
+        try? FileManager.default.removeItem(at: url)
+        try Shell.run(zip, ["-r", "-X", "-q", url.path, "[Content_Types].xml", "_rels", "xl"], currentDirectory: staging)
+    }
+
+    private static func sheetXML(_ rows: SpreadsheetConverter.Rows) -> String {
+        var xml = """
+        <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+        <worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><sheetData>
+        """
+        for (rowIndex, row) in rows.enumerated() {
+            xml += "<row r=\"\(rowIndex + 1)\">"
+            for (columnIndex, value) in row.enumerated() {
+                let reference = "\(columnName(columnIndex))\(rowIndex + 1)"
+                if let number = numberValue(value) {
+                    xml += "<c r=\"\(reference)\"><v>\(number)</v></c>"
+                } else {
+                    xml += "<c r=\"\(reference)\" t=\"inlineStr\"><is><t xml:space=\"preserve\">\(Markdown.escape(value))</t></is></c>"
+                }
+            }
+            xml += "</row>"
+        }
+        xml += "</sheetData></worksheet>"
+        return xml
+    }
+
+    /// Writes a number only when the value really is one, so phone numbers and
+    /// zero-padded ids stay text.
+    private static func numberValue(_ value: String) -> String? {
+        let trimmed = value.trimmed
+        guard !trimmed.isEmpty, trimmed == value else { return nil }
+        guard trimmed.rangeOfCharacter(from: CharacterSet(charactersIn: "0123456789")) != nil else { return nil }
+        guard let number = Double(trimmed), number.isFinite else { return nil }
+        if trimmed.count > 1, trimmed.hasPrefix("0"), !trimmed.hasPrefix("0.") { return nil }
+        return trimmed
+    }
+
+    static func columnName(_ index: Int) -> String {
+        var index = index
+        var name = ""
+        repeat {
+            name = String(UnicodeScalar(UInt8(65 + index % 26))) + name
+            index = index / 26 - 1
+        } while index >= 0
+        return name
+    }
+
+    static func columnIndex(_ reference: String) -> Int {
+        var index = 0
+        for character in reference.uppercased() {
+            guard let ascii = character.asciiValue, ascii >= 65, ascii <= 90 else { break }
+            index = index * 26 + Int(ascii - 64)
+        }
+        return max(0, index - 1)
+    }
+
+    // MARK: - Parsing helpers
+
+    private static func firstSheet(at staging: URL) -> URL? {
+        let worksheets = staging.appendingPathComponent("xl/worksheets")
+        let files = (try? FileManager.default.contentsOfDirectory(at: worksheets, includingPropertiesForKeys: nil)) ?? []
+        return files.filter { $0.pathExtension == "xml" }.sorted { $0.lastPathComponent < $1.lastPathComponent }.first
+    }
+
+    private static func parseSharedStrings(at url: URL) -> [String] {
+        guard let data = try? Data(contentsOf: url) else { return [] }
+        let parser = XMLParser(data: data)
+        let delegate = SharedStringsDelegate()
+        parser.delegate = delegate
+        parser.parse()
+        return delegate.strings
+    }
+
+    private static func parseSheet(at url: URL, sharedStrings: [String]) throws -> SpreadsheetConverter.Rows {
+        guard let data = try? Data(contentsOf: url) else {
+            throw ConversionError.failed("Could not read the worksheet.")
+        }
+        let parser = XMLParser(data: data)
+        let delegate = SheetDelegate(sharedStrings: sharedStrings)
+        parser.delegate = delegate
+        parser.parse()
+        return delegate.rows
+    }
+
+    private final class SharedStringsDelegate: NSObject, XMLParserDelegate {
+        var strings: [String] = []
+        private var current: String?
+        private var buffer = ""
+
+        func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName: String?, attributes: [String: String]) {
+            if elementName == "si" { current = ""; buffer = "" }
+            if elementName == "t" { buffer = "" }
+        }
+
+        func parser(_ parser: XMLParser, foundCharacters string: String) {
+            buffer += string
+        }
+
+        func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName: String?) {
+            if elementName == "t" { current = (current ?? "") + buffer }
+            if elementName == "si" { strings.append(current ?? ""); current = nil }
+        }
+    }
+
+    private final class SheetDelegate: NSObject, XMLParserDelegate {
+        let sharedStrings: [String]
+        var rows: SpreadsheetConverter.Rows = []
+        private var row: [String] = []
+        private var pendingColumn = 0
+        private var valueBuffer = ""
+        private var cellType = ""
+        private var isInline = false
+        private var inCell = false
+
+        init(sharedStrings: [String]) {
+            self.sharedStrings = sharedStrings
+        }
+
+        func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName: String?, attributes: [String: String]) {
+            switch elementName {
+            case "row":
+                row = []
+            case "c":
+                inCell = true
+                cellType = attributes["t"] ?? ""
+                isInline = false
+                valueBuffer = ""
+                if let reference = attributes["r"] {
+                    pendingColumn = XLSX.columnIndex(reference)
+                }
+            case "is":
+                isInline = true
+            case "v", "t":
+                valueBuffer = ""
+            default:
+                break
+            }
+        }
+
+        func parser(_ parser: XMLParser, foundCharacters string: String) {
+            if inCell { valueBuffer += string }
+        }
+
+        func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName: String?) {
+            switch elementName {
+            case "c":
+                let value: String
+                if cellType == "s", let index = Int(valueBuffer.trimmed), index < sharedStrings.count {
+                    value = sharedStrings[index]
+                } else {
+                    value = isInline ? valueBuffer : valueBuffer.trimmed
+                }
+                while row.count < pendingColumn { row.append("") }
+                row.append(value)
+                pendingColumn = row.count
+                inCell = false
+                valueBuffer = ""
+            case "row":
+                rows.append(row)
+                row = []
+            default:
+                break
+            }
+        }
+    }
+
+    // MARK: - Static OOXML scaffolding
+
+    private static let contentTypes = """
+    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+    <Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
+    <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>
+    <Default Extension="xml" ContentType="application/xml"/>
+    <Override PartName="/xl/workbook.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml"/>
+    <Override PartName="/xl/worksheets/sheet1.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml"/>
+    <Override PartName="/xl/styles.xml" ContentType="application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml"/>
+    </Types>
+    """
+
+    private static let packageRels = """
+    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+    <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+    <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="xl/workbook.xml"/>
+    </Relationships>
+    """
+
+    private static let workbookRels = """
+    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+    <Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+    <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/>
+    <Relationship Id="rId2" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/>
+    </Relationships>
+    """
+
+    private static let workbook = """
+    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+    <workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
+    <sheets><sheet name="Sheet1" sheetId="1" r:id="rId1"/></sheets></workbook>
+    """
+
+    private static let styles = """
+    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+    <styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
+    <fonts count="1"><font><sz val="11"/><name val="Calibri"/></font></fonts>
+    <fills count="1"><fill><patternFill patternType="none"/></fill></fills>
+    <borders count="1"><border/></borders>
+    <cellStyleXfs count="1"><xf numFmtId="0" fontId="0" fillId="0" borderId="0"/></cellStyleXfs>
+    <cellXfs count="1"><xf numFmtId="0" fontId="0" fillId="0" borderId="0" xfId="0"/></cellXfs>
+    </styleSheet>
+    """
+}
+
+/// ODS is a zip of `content.xml`; a light parser is enough for flat tables.
+enum ODS {
+    static func read(_ url: URL, cancellation: Cancellation? = nil) throws -> SpreadsheetConverter.Rows {
+        let staging = try Unzip.expand(url, cancellation: cancellation)
+        defer { try? FileManager.default.removeItem(at: staging) }
+        guard let data = try? Data(contentsOf: staging.appendingPathComponent("content.xml")) else {
+            throw ConversionError.failed("This ODS file has no content.xml.")
+        }
+        let parser = XMLParser(data: data)
+        let delegate = TableDelegate()
+        parser.delegate = delegate
+        parser.parse()
+        return delegate.rows
+    }
+
+    private final class TableDelegate: NSObject, XMLParserDelegate {
+        private(set) var rows: SpreadsheetConverter.Rows = []
+        private var row: [String] = []
+        private var buffer = ""
+        private var inCell = false
+        private var inRow = false
+        private var repeatColumns = 1
+
+        func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName: String?, attributes: [String: String]) {
+            switch elementName {
+            case "table-row":
+                inRow = true
+                row = []
+            case "table-cell":
+                inCell = true
+                buffer = ""
+                repeatColumns = Int(attributes["table:number-columns-repeated"] ?? "1") ?? 1
+            case "p":
+                if inCell, !buffer.isEmpty { buffer += " " }
+            default:
+                break
+            }
+        }
+
+        func parser(_ parser: XMLParser, foundCharacters string: String) {
+            if inCell { buffer += string }
+        }
+
+        func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName: String?) {
+            switch elementName {
+            case "table-cell":
+                let value = buffer.trimmed
+                for _ in 0..<min(repeatColumns, 256) { row.append(value) }
+                inCell = false
+            case "table-row":
+                if !row.allSatisfy({ $0.isEmpty }) { rows.append(row) }
+                inRow = false
+            case "table":
+                break
+            default:
+                break
+            }
+        }
+    }
+}
+
+enum Unzip {
+    /// Expands an archive and returns the staging directory the caller must
+    /// delete.
+    static func expand(_ url: URL, cancellation: Cancellation? = nil) throws -> URL {
+        let staging = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-unzip-\(UUID().uuidString)", isDirectory: true)
+        try FileManager.default.createDirectory(at: staging, withIntermediateDirectories: true)
+        do {
+            try Shell.run(Toolchain.unzip, ["-qq", "-o", url.path, "-d", staging.path], cancellation: cancellation)
+        } catch {
+            try? FileManager.default.removeItem(at: staging)
+            throw error
+        }
+        return staging
+    }
+}
diff --git a/Sources/Konverter/Convert/SubtitleConverter.swift b/Sources/Konverter/Convert/SubtitleConverter.swift
new file mode 100644
index 0000000..95e7be7
--- /dev/null
+++ b/Sources/Konverter/Convert/SubtitleConverter.swift
@@ -0,0 +1,146 @@
+import Foundation
+
+struct SubtitleCue {
+    var start: Double
+    var end: Double
+    var text: String
+}
+
+/// SRT ↔ VTT ↔ TXT, plus the offset tool.
+enum SubtitleConverter {
+    static func convert(
+        source: URL,
+        to format: Format,
+        at destination: URL,
+        cancellation: Cancellation? = nil
+    ) throws {
+        var cues = try parse(source)
+        try cancellation?.check()
+        cues = cues.map { cue in
+            var copy = cue
+            copy.text = SubtitleConverter.normalized(copy.text)
+            return copy
+        }
+        switch format {
+        case .srt, .vtt:
+            try write(cues, to: destination, format: format)
+        case .txt:
+            try TextDocument.write(cues.map(\.text).joined(separator: "\n"), to: destination)
+        default:
+            throw ConversionError.unsupported("Subtitles cannot become \(format.displayName).")
+        }
+    }
+
+    static func parse(_ url: URL) throws -> [SubtitleCue] {
+        guard let raw = try? String(contentsOf: url, encoding: .utf8)
+            ?? (try? String(contentsOf: url, encoding: .isoLatin1)) else {
+            throw ConversionError.unreadable(url.lastPathComponent)
+        }
+        let ext = FileKind.canonicalExtension(url.pathExtension)
+        switch ext {
+        case "vtt":
+            return parseBlocks(raw, timeSeparator: ".")
+        case "ass", "ssa":
+            return parseASS(raw)
+        default:
+            return parseBlocks(raw, timeSeparator: nil)
+        }
+    }
+
+    private static func parseBlocks(_ raw: String, timeSeparator: Character?) -> [SubtitleCue] {
+        let normalized = raw
+            .replacingOccurrences(of: "\r\n", with: "\n")
+            .replacingOccurrences(of: "\r", with: "\n")
+            .replacingOccurrences(of: "\u{FEFF}", with: "")
+        let blocks = normalized.components(separatedBy: "\n\n")
+        var cues: [SubtitleCue] = []
+
+        for block in blocks {
+            let lines = block.components(separatedBy: "\n").map { $0.trimmed }.filter { !$0.isEmpty }
+            guard let timeLineIndex = lines.firstIndex(where: { $0.contains("-->") }) else { continue }
+            let timeLine = lines[timeLineIndex]
+            let parts = timeLine.components(separatedBy: "-->")
+            guard parts.count == 2,
+                  let start = seconds(from: parts[0], separator: timeSeparator),
+                  let end = seconds(from: parts[1], separator: timeSeparator) else { continue }
+            let text = lines.dropFirst(timeLineIndex + 1).joined(separator: "\n")
+            cues.append(SubtitleCue(start: start, end: max(end, start), text: text.isEmpty ? " " : text))
+        }
+        return cues
+    }
+
+    private static func parseASS(_ raw: String) -> [SubtitleCue] {
+        var cues: [SubtitleCue] = []
+        for line in raw.components(separatedBy: "\n") where line.hasPrefix("Dialogue:") {
+            let fields = line.dropFirst("Dialogue:".count).components(separatedBy: ",")
+            guard fields.count >= 10,
+                  let start = seconds(from: fields[1], separator: nil),
+                  let end = seconds(from: fields[2], separator: nil) else { continue }
+            let text = fields[9...].joined(separator: ",")
+                .replacingOccurrences(of: "\\N", with: "\n")
+                .replacingOccurrences(of: "\\n", with: "\n")
+            cues.append(SubtitleCue(start: start, end: end, text: text))
+        }
+        return cues
+    }
+
+    static func write(_ cues: [SubtitleCue], to url: URL, format: Format) throws {
+        var output = format == .vtt ? "WEBVTT\n\n" : ""
+        for (index, cue) in cues.enumerated() {
+            if format == .srt {
+                output += "\(index + 1)\n"
+                output += "\(timecode(cue.start, separator: ",")) --> \(timecode(cue.end, separator: ","))\n"
+            } else {
+                output += "\(timecode(cue.start, separator: ".")) --> \(timecode(cue.end, separator: "."))\n"
+            }
+            output += cue.text + "\n\n"
+        }
+        try TextDocument.write(output, to: url)
+    }
+
+    static func shift(_ cues: [SubtitleCue], by offset: Double) -> [SubtitleCue] {
+        cues.map { cue in
+            var copy = cue
+            let shift = max(0, cue.start + offset) - cue.start
+            copy.start = max(0, cue.start + offset)
+            copy.end = max(copy.start, cue.end + shift)
+            return copy
+        }
+    }
+
+    private static func normalized(_ text: String) -> String {
+        var value = text
+        for tag in ["<i>", "</i>", "<b>", "</b>", "<u>", "</u>", "<font>", "</font>"] {
+            value = value.replacingOccurrences(of: tag, with: "")
+        }
+        return value
+    }
+
+    // MARK: - Timecodes
+
+    static func timecode(_ seconds: Double, separator: Character = ",") -> String {
+        let clamped = max(0, seconds)
+        let hours = Int(clamped) / 3600
+        let minutes = (Int(clamped) % 3600) / 60
+        let wholeSeconds = Int(clamped) % 60
+        let millis = Int(((clamped - Double(Int(clamped))) * 1000).rounded())
+        return String(format: "%02d:%02d:%02d%@%03d", hours, minutes, wholeSeconds, String(separator), millis)
+    }
+
+    private static func seconds(from text: String, separator: Character?) -> Double? {
+        let cleaned = text.trimmingCharacters(in: .whitespaces).replacingOccurrences(of: ",", with: ".")
+        let components = cleaned.components(separatedBy: ":")
+        var value: Double = 0
+        for (index, component) in components.enumerated() {
+            guard let number = Double(component) else { return nil }
+            switch components.count - index {
+            case 1: value += number
+            case 2: value += number * 60
+            case 3: value += number * 3600
+            default: return nil
+            }
+        }
+        _ = separator
+        return value
+    }
+}
diff --git a/Sources/Konverter/Convert/TextDocument.swift b/Sources/Konverter/Convert/TextDocument.swift
new file mode 100644
index 0000000..9195771
--- /dev/null
+++ b/Sources/Konverter/Convert/TextDocument.swift
@@ -0,0 +1,217 @@
+import AppKit
+import CoreText
+import Foundation
+
+/// Text extraction and rendering shared by the document, ebook, PDF and
+/// spreadsheet paths. `textutil` does the heavy lifting for Office formats;
+/// CoreText lays text out when we have to make a PDF ourselves.
+enum TextDocument {
+    static func plainText(from url: URL) -> String? {
+        switch FileKind.canonicalExtension(url.pathExtension) {
+        case "txt", "md", "csv", "tsv", "srt", "vtt":
+            return (try? String(contentsOf: url, encoding: .utf8))
+                ?? (try? String(contentsOf: url, encoding: .isoLatin1))
+        case "html":
+            if let html = try? String(contentsOf: url, encoding: .utf8) {
+                return textFromHTML(html)
+            }
+            return nil
+        case "epub":
+            return try? EbookConverter.plainText(url)
+        case "pdf":
+            return PDFConverter.extractText(url)
+        default:
+            return textutilText(from: url)
+        }
+    }
+
+    static func textFromHTML(_ html: String) -> String {
+        guard let data = html.data(using: .utf8),
+              let attributed = try? NSAttributedString(
+                data: data,
+                options: [.documentType: NSAttributedString.DocumentType.html,
+                          .characterEncoding: String.Encoding.utf8.rawValue],
+                documentAttributes: nil
+              ) else {
+            return Markdown.decodeEntities(Markdown.stripTags(html))
+        }
+        return attributed.string
+    }
+
+    static func textutilText(from url: URL) -> String? {
+        guard let result = try? Shell.run(Toolchain.textutil, ["-convert", "txt", "-stdout", url.path]) else {
+            return nil
+        }
+        return result.stdout
+    }
+
+    static func html(from url: URL) throws -> String {
+        switch FileKind.canonicalExtension(url.pathExtension) {
+        case "md":
+            let source = try String(contentsOf: url, encoding: .utf8)
+            return Markdown.html(from: source, title: url.deletingPathExtension().lastPathComponent)
+        case "html":
+            return try String(contentsOf: url, encoding: .utf8)
+        case "txt":
+            let source = try String(contentsOf: url, encoding: .utf8)
+            let escaped = Markdown.escape(source)
+            return "<!DOCTYPE html><html><head><meta charset=\"utf-8\"></head><body><pre>\(escaped)</pre></body></html>"
+        case "pdf":
+            let text = PDFConverter.extractText(url)
+            return htmlDocument(fromPlainText: text, title: url.deletingPathExtension().lastPathComponent)
+        case "epub":
+            return try EbookConverter.html(url)
+        default:
+            let result = try Shell.run(Toolchain.textutil, ["-convert", "html", "-stdout", url.path])
+            return result.stdout
+        }
+    }
+
+    static func attributedString(from url: URL) -> NSAttributedString? {
+        if let data = try? Data(contentsOf: url),
+           let attributed = try? NSAttributedString(
+            data: data,
+            options: [.documentType: documentType(for: url), .characterEncoding: String.Encoding.utf8.rawValue],
+            documentAttributes: nil
+           ) {
+            return attributed
+        }
+        // Fall back to HTML produced by textutil, which every Office format can
+        // be converted to.
+        if let html = try? html(from: url), let data = html.data(using: .utf8) {
+            return try? NSAttributedString(
+                data: data,
+                options: [.documentType: NSAttributedString.DocumentType.html,
+                          .characterEncoding: String.Encoding.utf8.rawValue],
+                documentAttributes: nil
+            )
+        }
+        return nil
+    }
+
+    private static func documentType(for url: URL) -> NSAttributedString.DocumentType {
+        switch FileKind.canonicalExtension(url.pathExtension) {
+        case "rtf": return .rtf
+        case "rtfd": return .rtfd
+        case "html": return .html
+        case "doc": return .docFormat
+        case "docx": return .officeOpenXML
+        case "odt": return .openDocument
+        default: return .plain
+        }
+    }
+
+    static func htmlDocument(fromPlainText text: String, title: String) -> String {
+        let paragraphs = text
+            .components(separatedBy: "\n\n")
+            .map { $0.trimmed }
+            .filter { !$0.isEmpty }
+            .map { "<p>" + Markdown.escape($0).replacingOccurrences(of: "\n", with: "<br/>") + "</p>" }
+            .joined(separator: "\n")
+        return """
+        <!DOCTYPE html><html><head><meta charset="utf-8"><title>\(Markdown.escape(title))</title>
+        <style>body{font:16px/1.6 -apple-system,sans-serif;max-width:720px;margin:48px auto;padding:0 24px}</style>
+        </head><body>\(paragraphs)</body></html>
+        """
+    }
+
+    static func write(_ text: String, to url: URL) throws {
+        try text.write(to: url, atomically: true, encoding: .utf8)
+    }
+
+    /// Converts text/HTML to an Office format with `textutil`.
+    static func textutilConvert(_ source: URL, to format: Format, at destination: URL, cancellation: Cancellation? = nil) throws {
+        guard let identifier = textutilIdentifier(for: format) else {
+            throw ConversionError.unsupported("textutil cannot write \(format.displayName).")
+        }
+        try Shell.run(
+            Toolchain.textutil,
+            ["-convert", identifier, "-output", destination.path, source.path],
+            cancellation: cancellation
+        )
+    }
+
+    static func textutilConvert(sourceHTML: String, to format: Format, at destination: URL, cancellation: Cancellation? = nil) throws {
+        let temporary = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-\(UUID().uuidString).html")
+        defer { try? FileManager.default.removeItem(at: temporary) }
+        try sourceHTML.write(to: temporary, atomically: true, encoding: .utf8)
+        try textutilConvert(temporary, to: format, at: destination, cancellation: cancellation)
+    }
+
+    private static func textutilIdentifier(for format: Format) -> String? {
+        switch format {
+        case .txt: return "txt"
+        case .html: return "html"
+        case .rtf: return "rtf"
+        case .docx: return "docx"
+        case .doc: return "doc"
+        case .odt: return "odt"
+        default: return nil
+        }
+    }
+
+    // MARK: - PDF layout
+
+    /// Paginates an attributed string into a PDF at A4 with 56 pt margins.
+    static func writePDF(_ attributed: NSAttributedString, to url: URL, pageSize: CGSize = CGSize(width: 595, height: 842)) throws {
+        let margin: CGFloat = 56
+        var mediaBox = CGRect(origin: .zero, size: pageSize)
+        guard let context = CGContext(url as CFURL, mediaBox: &mediaBox, nil) else {
+            throw ConversionError.failed("Could not create \(url.lastPathComponent).")
+        }
+
+        let text = NSMutableAttributedString(attributedString: attributed)
+        if text.length == 0 {
+            text.append(NSAttributedString(string: " "))
+        }
+        // A readable default for documents that carry no fonts.
+        text.enumerateAttribute(.font, in: NSRange(location: 0, length: text.length)) { value, range, _ in
+            if value == nil {
+                text.addAttribute(.font, value: NSFont.systemFont(ofSize: 12), range: range)
+            }
+        }
+
+        let framesetter = CTFramesetterCreateWithAttributedString(text as CFAttributedString)
+        let textRect = CGRect(
+            x: margin,
+            y: margin,
+            width: pageSize.width - margin * 2,
+            height: pageSize.height - margin * 2
+        )
+        let path = CGPath(rect: textRect, transform: nil)
+
+        var cursor = 0
+        let total = text.length
+        repeat {
+            context.beginPDFPage(nil)
+            let frame = CTFramesetterCreateFrame(
+                framesetter,
+                CFRange(location: cursor, length: 0),
+                path,
+                nil
+            )
+            CTFrameDraw(frame, context)
+            context.endPDFPage()
+
+            let visible = CTFrameGetVisibleStringRange(frame)
+            if visible.length <= 0 { break }
+            cursor = visible.location + visible.length
+        } while cursor < total
+
+        context.closePDF()
+    }
+
+    static func writePDF(fromText text: String, to url: URL, pageSize: CGSize = CGSize(width: 595, height: 842)) throws {
+        let style = NSMutableParagraphStyle()
+        style.lineSpacing = 3
+        let attributed = NSAttributedString(
+            string: text,
+            attributes: [
+                .font: NSFont.systemFont(ofSize: 12),
+                .paragraphStyle: style
+            ]
+        )
+        try writePDF(attributed, to: url, pageSize: pageSize)
+    }
+}
diff --git a/Sources/Konverter/Convert/ToolRunner.swift b/Sources/Konverter/Convert/ToolRunner.swift
new file mode 100644
index 0000000..2a2cc9a
--- /dev/null
+++ b/Sources/Konverter/Convert/ToolRunner.swift
@@ -0,0 +1,446 @@
+import AppKit
+import Foundation
+import PDFKit
+
+/// What a tool produced. `message` is for the read-only tools (Info, Read QR,
+/// List Contents, Statistics) which show a result instead of writing a file.
+struct ToolOutcome {
+    var outputs: [URL] = []
+    var message: String?
+    var messageTitle: String?
+    var revealInFinder: Bool = true
+}
+
+/// Runs a `ToolID` over one or more files. Every tool is written so that a
+/// failure on one file does not silently swallow the rest: the first error is
+/// reported after the successful outputs are collected.
+enum ToolRunner {
+    static func run(
+        tool: ToolID,
+        inputs: [URL],
+        params: ToolParams,
+        cancellation: Cancellation? = nil,
+        progress: ((Double) -> Void)? = nil
+    ) throws -> ToolOutcome {
+        guard inputs.count >= tool.minimumFileCount else {
+            throw ConversionError.failed("\(tool.title) needs at least \(tool.minimumFileCount) files.")
+        }
+        try cancellation?.check()
+
+        switch tool {
+        case .compressImage:
+            let quality = Double(params.int("quality", default: 70)) / 100
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let format = FileKind.format(of: source) ?? .jpg
+                let destination = OutputNaming.sibling(for: source, suffix: "-compressed")
+                try ImageTools.compress(source, at: destination, format: format, quality: quality)
+                return destination
+            }
+
+        case .resizeImage:
+            let width = params.int("width", default: 1920)
+            let height = params.int("height", default: 1920)
+            let percent = params.int("percent", default: 100)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-resized")
+                try ImageTools.resize(source, at: destination, maxWidth: width, maxHeight: height, percent: percent)
+                return destination
+            }
+
+        case .cropImage:
+            let inset = params.int("inset", default: 0)
+            let aspect = params.string("aspect", default: "Keep")
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-cropped")
+                try ImageTools.crop(source, at: destination, inset: inset, aspect: aspect)
+                return destination
+            }
+
+        case .rotateImage:
+            let degrees = params.string("angle", default: "90° right").hasPrefix("90° r") ? 90 : (params.string("angle", default: "").hasPrefix("180") ? 180 : -90)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-rotated")
+                try ImageTools.rotate(source, at: destination, degrees: degrees)
+                return destination
+            }
+
+        case .flipImage:
+            let horizontal = params.string("axis", default: "Horizontal") == "Horizontal"
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-flipped")
+                try ImageTools.flip(source, at: destination, horizontal: horizontal)
+                return destination
+            }
+
+        case .grayscaleImage:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-gray", extension: "png")
+                try ImageTools.grayscale(source, at: destination)
+                return destination
+            }
+
+        case .stripMetadata:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let format = FileKind.format(of: source) ?? .jpg
+                let destination = OutputNaming.sibling(for: source, suffix: "-clean")
+                try ImageTools.stripMetadata(source, at: destination, format: format)
+                return destination
+            }
+
+        case .watermarkImage:
+            let text = params.string("text", default: "©")
+            let position = params.string("position", default: "Bottom Right")
+            let opacity = Double(params.int("opacity", default: 45))
+            let size = Double(params.int("size", default: 16))
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-watermark")
+                try ImageTools.watermark(source, at: destination, text: text, position: position, opacity: opacity, sizePercent: size)
+                return destination
+            }
+
+        case .readQR:
+            var results: [String] = []
+            for source in inputs {
+                try cancellation?.check()
+                let payload = ImageTools.readQR(source)
+                results.append("\(source.lastPathComponent):\n\(payload ?? "No barcode found")")
+            }
+            return ToolOutcome(message: results.joined(separator: "\n\n"), messageTitle: "Barcode")
+
+        case .compressVideo:
+            let quality = params.string("preset", default: "Medium")
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let ext = container(for: source, fallback: "mp4")
+                let destination = OutputNaming.sibling(for: source, suffix: "-compressed", extension: ext)
+                try MediaTools.compressVideo(source, at: destination, quality: quality)
+                return destination
+            }
+
+        case .trimVideo, .trimAudio:
+            let start = Timecode.seconds(from: params.string("start", default: "0")) ?? 0
+            let end = Timecode.seconds(from: params.string("end", default: ""))
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let ext = container(for: source, fallback: tool == .trimAudio ? "m4a" : "mp4")
+                let destination = OutputNaming.sibling(for: source, suffix: "-trimmed", extension: ext)
+                try trim(source, at: destination, start: start, end: end, cancellation: cancellation)
+                return destination
+            }
+
+        case .muteVideo:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let ext = container(for: source, fallback: "mp4")
+                let destination = OutputNaming.sibling(for: source, suffix: "-muted", extension: ext)
+                try AVConverter.mute(source: source, at: destination, cancellation: cancellation)
+                return destination
+            }
+
+        case .speedVideo, .speedAudio:
+            let rate = params.double("rate", default: 2)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let ext = container(for: source, fallback: tool == .speedAudio ? "m4a" : "mp4")
+                let destination = OutputNaming.sibling(for: source, suffix: "-\(rateString(rate))x", extension: ext)
+                try AVConverter.changeSpeed(source: source, at: destination, rate: rate, cancellation: cancellation)
+                return destination
+            }
+
+        case .snapshotVideo:
+            let at = Timecode.seconds(from: params.string("at", default: "1")) ?? 1
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-frame", extension: "png")
+                try AVConverter.snapshot(source: source, at: destination, time: at, cancellation: cancellation)
+                return destination
+            }
+
+        case .videoToGIF:
+            let fps = params.int("fps", default: 12)
+            let width = params.int("width", default: 480)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "", extension: "gif")
+                try AVConverter.makeGIF(source: source, at: destination, fps: fps, maxWidth: width, cancellation: cancellation)
+                return destination
+            }
+
+        case .resizeVideo:
+            let width = params.int("width", default: 1280)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let ext = container(for: source, fallback: "mp4")
+                let destination = OutputNaming.sibling(for: source, suffix: "-resized", extension: ext)
+                try AVConverter.resize(source: source, at: destination, width: width, cancellation: cancellation)
+                return destination
+            }
+
+        case .normalizeAudio:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = MediaTools.audioSibling(for: source, suffix: "-normalized")
+                try MediaTools.normalizeAudio(source, at: destination)
+                return destination
+            }
+
+        case .channelsAudio:
+            let mono = params.string("mode", default: "Mono") == "Mono"
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = MediaTools.audioSibling(for: source, suffix: mono ? "-mono" : "-stereo")
+                try MediaTools.channels(source, at: destination, mono: mono)
+                return destination
+            }
+
+        case .bleepAudio:
+            let start = Timecode.seconds(from: params.string("start", default: "0")) ?? 0
+            let end = Timecode.seconds(from: params.string("end", default: "1")) ?? 1
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = MediaTools.audioSibling(for: source, suffix: "-bleeped")
+                try MediaTools.bleep(source, at: destination, start: start, end: max(end, start + 0.05))
+                return destination
+            }
+
+        case .compressAudio:
+            let bitrate = params.string("bitrate", default: "128")
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = MediaTools.audioSibling(for: source, suffix: "-compressed")
+                try MediaTools.compressAudio(source, at: destination, bitrate: bitrate)
+                return destination
+            }
+
+        case .mergePDF:
+            let first = inputs[0]
+            let destination = OutputNaming.availableURL(
+                for: first.deletingLastPathComponent()
+                    .appendingPathComponent(first.deletingPathExtension().lastPathComponent + " merged.pdf")
+            )
+            try PDFConverter.merge(inputs, at: destination, cancellation: cancellation)
+            progress?(1)
+            return ToolOutcome(outputs: [destination])
+
+        case .splitPDF:
+            let perFile = max(1, params.int("pages", default: 1))
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let directory = OutputNaming.artifactDirectory(for: source, suffix: " split")
+                let written = try PDFConverter.split(source, pagesPerFile: perFile, into: directory, cancellation: cancellation)
+                guard let first = written.first else { throw ConversionError.failed("Nothing to split.") }
+                return first
+            }
+
+        case .rotatePDF:
+            let angle = params.string("angle", default: "90° right")
+            let degrees = angle.hasPrefix("180") ? 180 : (angle.hasPrefix("90° l") ? -90 : 90)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-rotated", extension: "pdf")
+                try PDFConverter.rotate(source, degrees: degrees, at: destination)
+                return destination
+            }
+
+        case .compressPDF:
+            let quality = Double(params.int("quality", default: 55)) / 100
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-compressed", extension: "pdf")
+                try PDFConverter.compress(source, at: destination, quality: quality, cancellation: cancellation)
+                return destination
+            }
+
+        case .encryptPDF:
+            let password = params.string("password", default: "")
+            guard !password.isEmpty else { throw ConversionError.failed("Enter a password first.") }
+            let owner = params.string("owner", default: "")
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-encrypted", extension: "pdf")
+                try PDFConverter.encrypt(source, at: destination, password: password, ownerPassword: owner)
+                return destination
+            }
+
+        case .decryptPDF:
+            let password = params.string("password", default: "")
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "-decrypted", extension: "pdf")
+                guard let document = PDFDocument(url: source),
+                      document.unlock(withPassword: password) || !document.isLocked else {
+                    throw ConversionError.failed("Wrong password or the PDF is not encrypted.")
+                }
+                guard document.write(to: destination) else {
+                    throw ConversionError.failed("Could not write the decrypted PDF.")
+                }
+                return destination
+            }
+
+        case .imagesToPDF:
+            let images: [(CGImage, String?)] = try inputs.map { source in
+                guard let image = Raster.firstImage(at: source) else {
+                    throw ConversionError.unreadable(source.lastPathComponent)
+                }
+                return (image, source.lastPathComponent)
+            }
+            let first = inputs[0]
+            let destination = OutputNaming.availableURL(
+                for: first.deletingLastPathComponent()
+                    .appendingPathComponent(first.deletingPathExtension().lastPathComponent + " images.pdf")
+            )
+            try PDFConverter.imagesToPDF(images, at: destination, cancellation: cancellation)
+            progress?(1)
+            return ToolOutcome(outputs: [destination])
+
+        case .collageImages:
+            let columns = max(1, params.int("columns", default: 3))
+            let page = params.string("page", default: "A4")
+            let margin = Double(params.int("margin", default: 24))
+            let captions = params.bool("captions", default: false)
+            let entries: [(CGImage, String)] = try inputs.map { source in
+                guard let image = Raster.firstImage(at: source) else {
+                    throw ConversionError.unreadable(source.lastPathComponent)
+                }
+                return (image, source.lastPathComponent)
+            }
+            let first = inputs[0]
+            let destination = OutputNaming.availableURL(
+                for: first.deletingLastPathComponent()
+                    .appendingPathComponent(first.deletingPathExtension().lastPathComponent + " collage.pdf")
+            )
+            try PDFConverter.collage(
+                entries,
+                at: destination,
+                columns: columns,
+                page: page,
+                margin: margin,
+                captions: captions,
+                cancellation: cancellation
+            )
+            progress?(1)
+            return ToolOutcome(outputs: [destination])
+
+        case .extractPDFText:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let text = PDFConverter.extractText(source)
+                guard !text.trimmed.isEmpty else {
+                    throw ConversionError.failed("No text layer in \(source.lastPathComponent).")
+                }
+                let destination = OutputNaming.sibling(for: source, suffix: "", extension: "txt")
+                try TextDocument.write(text, to: destination)
+                return destination
+            }
+
+        case .documentToPDF:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let destination = OutputNaming.sibling(for: source, suffix: "", extension: "pdf")
+                try DocumentConverter.convert(source: source, to: .pdf, at: destination, cancellation: cancellation)
+                return destination
+            }
+
+        case .wordCount:
+            var results: [String] = []
+            for source in inputs {
+                try cancellation?.check()
+                let text = TextDocument.plainText(from: source) ?? ""
+                let words = text.split { $0 == " " || $0.isNewline }.count
+                let lines = text.components(separatedBy: "\n").count
+                results.append("""
+                \(source.lastPathComponent)
+                \(words) words · \(text.count) characters · \(lines) lines
+                """)
+            }
+            return ToolOutcome(message: results.joined(separator: "\n\n"), messageTitle: "Statistics")
+
+        case .sheetsToCSV:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let rows = try SpreadsheetConverter.read(source, cancellation: cancellation)
+                let destination = OutputNaming.sibling(for: source, suffix: "", extension: "csv")
+                try SpreadsheetConverter.write(rows, to: destination, delimiter: ",")
+                return destination
+            }
+
+        case .shiftSubtitle:
+            let offset = params.double("offset", default: 0)
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let format = FileKind.format(of: source) ?? .srt
+                let cues = SubtitleConverter.shift(try SubtitleConverter.parse(source), by: offset)
+                let destination = OutputNaming.sibling(for: source, suffix: "-shifted")
+                try SubtitleConverter.write(cues, to: destination, format: format == .vtt ? .vtt : .srt)
+                return destination
+            }
+
+        case .extractArchive:
+            return try mapFiles(inputs, cancellation: cancellation, progress: progress) { source in
+                let directory = OutputNaming.artifactDirectory(for: source, suffix: " extracted")
+                let result = try ArchiveConverter.extract(source: source, into: directory, cancellation: cancellation, progress: nil)
+                return result
+            }
+
+        case .listArchive:
+            var results: [String] = []
+            for source in inputs {
+                try cancellation?.check()
+                results.append("\(source.lastPathComponent)\n\((try? ArchiveConverter.list(source)) ?? "Unreadable")")
+            }
+            return ToolOutcome(message: results.joined(separator: "\n\n"), messageTitle: "Archive")
+
+        case .mediaInfo:
+            var results: [String] = []
+            for source in inputs {
+                try cancellation?.check()
+                results.append(MediaInfo.describe(source))
+            }
+            return ToolOutcome(message: results.joined(separator: "\n\n"), messageTitle: "Info")
+        }
+    }
+
+    // MARK: - Helpers
+
+    private static func mapFiles(
+        _ inputs: [URL],
+        cancellation: Cancellation?,
+        progress: ((Double) -> Void)?,
+        _ transform: (URL) throws -> URL
+    ) throws -> ToolOutcome {
+        var outputs: [URL] = []
+        var firstError: Error?
+        for (index, source) in inputs.enumerated() {
+            try cancellation?.check()
+            do {
+                let output = try transform(source)
+                outputs.append(output)
+            } catch is CancellationError {
+                throw CancellationError()
+            } catch {
+                if firstError == nil { firstError = error }
+            }
+            progress?(Double(index + 1) / Double(inputs.count))
+        }
+        if outputs.isEmpty, let firstError { throw firstError }
+        return ToolOutcome(outputs: outputs)
+    }
+
+    /// Keeps the source container when it is one we can write, otherwise uses
+    /// the fallback (`mp4` for video, `m4a` for audio).
+    private static func container(for source: URL, fallback: String) -> String {
+        let ext = FileKind.canonicalExtension(source.pathExtension)
+        let videoContainers = ["mp4", "mov", "m4v"]
+        let audioContainers = ["m4a", "mp3", "wav", "aiff", "flac", "ogg", "opus", "wma"]
+        if videoContainers.contains(ext) || audioContainers.contains(ext) { return ext }
+        return fallback
+    }
+
+    private static func rateString(_ rate: Double) -> String {
+        rate == rate.rounded() ? String(Int(rate)) : String(format: "%.2f", rate)
+    }
+
+    private static func trim(_ source: URL, at destination: URL, start: Double, end: Double?, cancellation: Cancellation?) throws {
+        let ext = FileKind.canonicalExtension(source.pathExtension)
+        if ["mp4", "mov", "m4v", "m4a"].contains(ext) {
+            try AVConverter.trim(source: source, at: destination, start: start, end: end, cancellation: cancellation)
+            return
+        }
+        if Toolchain.hasFFmpeg, Settings.shared.useExternalTools {
+            var arguments = ["-ss", String(format: "%.3f", start)]
+            if let end, end > start { arguments += ["-t", String(format: "%.3f", end - start)] }
+            arguments += ["-c:a", "copy"]
+            try FFmpeg.filter(source: source, at: destination, arguments: arguments)
+            return
+        }
+        if ["wav", "aiff"].contains(ext) {
+            let staged = FileManager.default.temporaryDirectory
+                .appendingPathComponent("konverter-trim-\(UUID().uuidString).m4a")
+            defer { try? FileManager.default.removeItem(at: staged) }
+            try AVConverter.trim(source: source, at: staged, start: start, end: end, cancellation: cancellation)
+            try CoreAudio.convert(source: staged, to: FileKind.format(of: destination) ?? .wav, at: destination, cancellation: cancellation)
+            return
+        }
+        throw ConversionError.missingTool("Trimming .\(ext) needs ffmpeg — brew install ffmpeg")
+    }
+}
diff --git a/Sources/Konverter/Core/Actions.swift b/Sources/Konverter/Core/Actions.swift
new file mode 100644
index 0000000..6fb44df
--- /dev/null
+++ b/Sources/Konverter/Core/Actions.swift
@@ -0,0 +1,144 @@
+import AppKit
+import Foundation
+
+/// The Control wheel: things you can do with a file that are not conversions.
+enum ActionID: String, CaseIterable, Identifiable, Codable {
+    case airdrop, float, copy, move, copyPath, terminal, revealInFinder
+
+    var id: String { rawValue }
+
+    var title: String {
+        switch self {
+        case .airdrop: return "AirDrop"
+        case .float: return "Float"
+        case .copy: return "Copy"
+        case .move: return "Move"
+        case .copyPath: return "Copy Path"
+        case .terminal: return "Terminal"
+        case .revealInFinder: return "Reveal"
+        }
+    }
+
+    var symbol: String {
+        switch self {
+        case .airdrop: return "airdrop"
+        case .float: return "macwindow.on.rectangle"
+        case .copy: return "doc.on.doc"
+        case .move: return "arrow.right.doc.on.clipboard"
+        case .copyPath: return "text.cursor"
+        case .terminal: return "terminal"
+        case .revealInFinder: return "folder"
+        }
+    }
+}
+
+enum ActionError: LocalizedError {
+    case needsSingleFile
+    case noDestination
+    case unavailable(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .needsSingleFile: return "This action works on one file at a time."
+        case .noDestination: return "No destination folder was chosen."
+        case .unavailable(let reason): return reason
+        }
+    }
+}
+
+/// File actions never touch the file's contents, and never use a conversion
+/// slot — matching Tangerine's behaviour.
+enum FileActions {
+    @MainActor
+    static func perform(_ action: ActionID, urls: [URL], settings: Settings = .shared) async throws {
+        guard !urls.isEmpty else { throw ActionError.noDestination }
+        switch action {
+        case .airdrop:
+            try performAirDrop(urls: urls)
+        case .float:
+            FloatPanel.shared.show(urls: urls)
+        case .copy:
+            if let destination = try await chooseDestination() {
+                try transfer(urls: urls, to: destination, moving: false)
+            }
+        case .move:
+            if let destination = try await chooseDestination() {
+                try transfer(urls: urls, to: destination, moving: true)
+            }
+        case .copyPath:
+            copyPaths(urls: urls)
+        case .terminal:
+            try openTerminal(urls: urls)
+        case .revealInFinder:
+            NSWorkspace.shared.activateFileViewerSelecting(urls)
+        }
+    }
+
+    @MainActor
+    private static func performAirDrop(urls: [URL]) throws {
+        guard let service = NSSharingService(named: .sendViaAirDrop) else {
+            throw ActionError.unavailable("AirDrop is not available on this Mac.")
+        }
+        guard service.canPerform(withItems: urls) else {
+            throw ActionError.unavailable("AirDrop cannot send this selection.")
+        }
+        service.perform(withItems: urls)
+    }
+
+    @MainActor
+    private static func chooseDestination() async throws -> URL? {
+        let panel = NSOpenPanel()
+        panel.canChooseFiles = false
+        panel.canChooseDirectories = true
+        panel.allowsMultipleSelection = false
+        panel.canCreateDirectories = true
+        panel.prompt = "Choose"
+        panel.message = "Choose a destination folder"
+        panel.directoryURL = Settings.shared.resolvedOutputFolder
+        NSApp.activate(ignoringOtherApps: true)
+        return panel.runModal() == .OK ? panel.url : nil
+    }
+
+    private static func transfer(urls: [URL], to destination: URL, moving: Bool) throws {
+        let manager = FileManager.default
+        for url in urls {
+            var target = destination.appendingPathComponent(url.lastPathComponent)
+            target = OutputNaming.availableURL(for: target)
+            do {
+                if moving {
+                    try manager.moveItem(at: url, to: target)
+                } else {
+                    try manager.copyItem(at: url, to: target)
+                }
+            } catch {
+                throw ActionError.unavailable("Could not \(moving ? "move" : "copy") \(url.lastPathComponent): \(error.localizedDescription)")
+            }
+        }
+    }
+
+    @MainActor
+    private static func copyPaths(urls: [URL]) {
+        let text = urls.map(\.path).joined(separator: "\n")
+        let pasteboard = NSPasteboard.general
+        pasteboard.clearContents()
+        pasteboard.setString(text, forType: .string)
+        Notifier.flash(
+            title: urls.count == 1 ? "Path copied" : "\(urls.count) paths copied",
+            body: text.count > 120 ? String(text.prefix(120)) + "…" : text
+        )
+    }
+
+    @MainActor
+    private static func openTerminal(urls: [URL]) throws {
+        let directory = urls[0].deletingLastPathComponent()
+        let terminal = URL(fileURLWithPath: "/System/Applications/Utilities/Terminal.app")
+        let configuration = NSWorkspace.OpenConfiguration()
+        NSWorkspace.shared.open([directory], withApplicationAt: terminal, configuration: configuration) { _, error in
+            if let error {
+                DispatchQueue.main.async {
+                    Notifier.error("Terminal", error.localizedDescription)
+                }
+            }
+        }
+    }
+}
diff --git a/Sources/Konverter/Core/Format.swift b/Sources/Konverter/Core/Format.swift
new file mode 100644
index 0000000..5dc6a0a
--- /dev/null
+++ b/Sources/Konverter/Core/Format.swift
@@ -0,0 +1,296 @@
+import Foundation
+
+/// The broad family a file belongs to. Drives which wheel is shown and which
+/// converter runs.
+enum FileCategory: String, CaseIterable, Identifiable, Codable {
+    case image, video, audio, pdf, document, slides, spreadsheet, ebook, subtitle, archive, folder, unknown
+
+    var id: String { rawValue }
+
+    var title: String {
+        switch self {
+        case .image: return "Images"
+        case .video: return "Video"
+        case .audio: return "Audio"
+        case .pdf: return "PDF"
+        case .document: return "Documents"
+        case .slides: return "Slides"
+        case .spreadsheet: return "Spreadsheets"
+        case .ebook: return "EPUB"
+        case .subtitle: return "Subtitles"
+        case .archive: return "Archives"
+        case .folder: return "Folders"
+        case .unknown: return "Files"
+        }
+    }
+
+    var symbol: String {
+        switch self {
+        case .image: return "photo"
+        case .video: return "film"
+        case .audio: return "waveform"
+        case .pdf: return "doc.richtext"
+        case .document: return "doc.text"
+        case .slides: return "rectangle.on.rectangle.angled"
+        case .spreadsheet: return "tablecells"
+        case .ebook: return "book"
+        case .subtitle: return "captions.bubble"
+        case .archive: return "doc.zipper"
+        case .folder: return "folder"
+        case .unknown: return "doc"
+        }
+    }
+
+    /// Wheels only make sense for these.
+    static var convertible: [FileCategory] {
+        [.image, .video, .audio, .pdf, .document, .slides, .spreadsheet, .ebook, .subtitle, .archive]
+    }
+}
+
+/// A canonical output extension.
+enum Format: String, CaseIterable, Identifiable, Codable, Hashable {
+    // Images
+    case jpg, png, heic, webp, tiff, bmp, gif, avif, svg, ico
+    // Documents
+    case pdf
+    case docx, doc, pages, rtf, txt, md, html, odt, epub
+    // Slides
+    case pptx, ppt, key
+    // Spreadsheets
+    case xlsx, xls, ods, csv, tsv, numbers
+    // Audio
+    case mp3, m4a, wav, flac, ogg, opus, aiff, wma
+    // Video
+    case mp4, mov, mkv, webm, avi, wmv, m4v
+    // Subtitles
+    case srt, vtt
+    // Archives
+    case zip, tar, gzip
+
+    var id: String { rawValue }
+    var ext: String { rawValue }
+    var displayName: String { rawValue.uppercased() }
+
+    /// Which wheel this format belongs to when offered as an output.
+    var category: FileCategory {
+        switch self {
+        case .jpg, .png, .heic, .webp, .tiff, .bmp, .gif, .avif, .svg, .ico: return .image
+        case .pdf: return .pdf
+        case .docx, .doc, .pages, .rtf, .txt, .md, .html, .odt: return .document
+        case .epub: return .ebook
+        case .pptx, .ppt, .key: return .slides
+        case .xlsx, .xls, .ods, .csv, .tsv, .numbers: return .spreadsheet
+        case .mp3, .m4a, .wav, .flac, .ogg, .opus, .aiff, .wma: return .audio
+        case .mp4, .mov, .mkv, .webm, .avi, .wmv, .m4v: return .video
+        case .srt, .vtt: return .subtitle
+        case .zip, .tar, .gzip: return .archive
+        }
+    }
+
+    var symbol: String {
+        switch self {
+        case .jpg, .png, .heic, .webp, .tiff, .bmp, .gif, .avif, .ico: return "photo"
+        case .svg: return "scribble.variable"
+        case .pdf: return "doc.richtext"
+        case .md: return "text.alignleft"
+        case .txt: return "doc.plaintext"
+        case .html: return "chevron.left.forwardslash.chevron.right"
+        case .docx, .doc: return "doc.text"
+        case .rtf: return "doc.richtext"
+        case .odt: return "doc.text"
+        case .pages: return "doc.text"
+        case .epub: return "book"
+        case .pptx, .ppt: return "rectangle.on.rectangle.angled"
+        case .key: return "rectangle.on.rectangle.angled"
+        case .xlsx, .xls: return "tablecells"
+        case .ods: return "tablecells"
+        case .csv, .tsv: return "tablecells.badge.ellipsis"
+        case .numbers: return "tablecells"
+        case .mp3, .m4a: return "waveform"
+        case .wav, .flac, .aiff: return "waveform"
+        case .ogg, .opus, .wma: return "waveform"
+        case .mp4, .mov, .mkv, .webm, .avi, .wmv, .m4v: return "film"
+        case .srt, .vtt: return "captions.bubble"
+        case .zip, .tar, .gzip: return "doc.zipper"
+        }
+    }
+
+    /// Uniform type identifier, also used for ImageIO destinations.
+    var uti: String? {
+        switch self {
+        case .jpg: return "public.jpeg"
+        case .png: return "public.png"
+        case .heic: return "public.heic"
+        case .webp: return "org.webmproject.webp"
+        case .tiff: return "public.tiff"
+        case .bmp: return "com.microsoft.bmp"
+        case .gif: return "com.compuserve.gif"
+        case .avif: return "public.avif"
+        case .svg: return "public.svg-image"
+        case .ico: return "com.microsoft.ico"
+        case .pdf: return "com.adobe.pdf"
+        case .txt: return "public.plain-text"
+        case .html: return "public.html"
+        case .rtf: return "public.rtf"
+        case .docx: return "org.openxmlformats.wordprocessingml.document"
+        case .doc: return "com.microsoft.word.doc"
+        case .odt: return "org.oasis-open.opendocument.text"
+        case .epub: return "org.idpf.epub-container"
+        case .pptx: return "org.openxmlformats.presentationml.presentation"
+        case .xlsx: return "org.openxmlformats.spreadsheetml.sheet"
+        case .csv: return "public.comma-separated-values-text"
+        case .tsv: return "public.tab-separated-values-text"
+        case .mp3: return "public.mp3"
+        case .m4a: return "public.mpeg-4-audio"
+        case .wav: return "com.microsoft.waveform-audio"
+        case .aiff: return "public.aiff-audio"
+        case .flac: return "org.xiph.flac"
+        case .ogg: return "org.xiph.ogg"
+        case .opus: return "org.xiph.opus"
+        case .mp4: return "public.mpeg-4"
+        case .mov: return "com.apple.quicktime-movie"
+        case .mkv: return "org.matroska.mkv"
+        case .srt: return "public.srt-subtitle"
+        case .vtt: return "public.vtt-subtitle"
+        case .zip: return "public.zip-archive"
+        case .tar: return "public.tar-archive"
+        case .gzip: return "org.gnu.gnu-zip-archive"
+        default: return nil
+        }
+    }
+
+    /// Formats Apple's frameworks cannot *write*; ffmpeg is required.
+    var requiresFFmpeg: Bool {
+        switch self {
+        case .mkv, .webm, .avi, .wmv, .mp3, .flac, .ogg, .opus, .wma: return true
+        default: return false
+        }
+    }
+
+    /// Formats that need LibreOffice to write with real layout fidelity.
+    var requiresLibreOffice: Bool {
+        switch self {
+        case .pages, .key, .numbers, .ppt, .pptx, .xls: return true
+        default: return false
+        }
+    }
+
+    /// Lossy formats take a quality knob.
+    var isLossy: Bool {
+        switch self {
+        case .jpg, .heic, .avif, .webp, .mp3, .m4a, .ogg, .opus, .wma, .mp4, .mkv, .webm, .avi, .wmv, .m4v:
+            return true
+        default:
+            return false
+        }
+    }
+
+    static func from(extension ext: String) -> Format? {
+        Format(rawValue: FileKind.canonicalExtension(ext))
+    }
+}
+
+/// Input side: figure out what a dropped file is.
+enum FileKind {
+    private static let extensionMap: [String: FileCategory] = [
+        // Images
+        "jpg": .image, "jpeg": .image, "png": .image, "heic": .image, "heif": .image,
+        "webp": .image, "tif": .image, "tiff": .image, "bmp": .image, "gif": .image,
+        "avif": .image, "svg": .image, "ico": .image, "jp2": .image, "psd": .image,
+        "exr": .image, "tga": .image, "raw": .image, "dng": .image, "cr2": .image,
+        // Video
+        "mp4": .video, "mov": .video, "m4v": .video, "mkv": .video, "webm": .video,
+        "avi": .video, "wmv": .video, "flv": .video, "mpg": .video, "mpeg": .video,
+        "3gp": .video, "ts": .video, "mts": .video,
+        // Audio
+        "mp3": .audio, "m4a": .audio, "m4b": .audio, "m4r": .audio, "wav": .audio,
+        "flac": .audio, "ogg": .audio, "oga": .audio, "opus": .audio, "aiff": .audio,
+        "aif": .audio, "aifc": .audio, "wma": .audio, "caf": .audio, "aac": .audio,
+        "ape": .audio,
+        // PDF
+        "pdf": .pdf,
+        // Documents
+        "docx": .document, "doc": .document, "rtf": .document, "rtfd": .document,
+        "odt": .document, "txt": .document, "text": .document, "md": .document,
+        "markdown": .document, "html": .document, "htm": .document, "xml": .document,
+        "webarchive": .document, "wordml": .document, "tex": .document, "log": .document,
+        "pages": .document,
+        // Slides
+        "ppt": .slides, "pptx": .slides, "key": .slides, "odp": .slides,
+        // Spreadsheets
+        "xlsx": .spreadsheet, "xls": .spreadsheet, "ods": .spreadsheet, "csv": .spreadsheet,
+        "tsv": .spreadsheet, "numbers": .spreadsheet,
+        // Ebook
+        "epub": .ebook, "mobi": .ebook, "azw3": .ebook,
+        // Subtitles
+        "srt": .subtitle, "vtt": .subtitle, "ass": .subtitle, "ssa": .subtitle, "sub": .subtitle,
+        // Archives
+        "zip": .archive, "tar": .archive, "gz": .archive, "tgz": .archive, "bz2": .archive,
+        "xz": .archive, "rar": .archive, "7z": .archive, "zst": .archive
+    ]
+
+    private static let canonicalMap: [String: String] = [
+        "jpeg": "jpg", "tif": "tiff", "markdown": "md", "htm": "html", "text": "txt",
+        "tgz": "tar", "aif": "aiff", "aifc": "aiff", "oga": "ogg", "m4b": "m4a",
+        "heif": "heic", "wordml": "odt"
+    ]
+
+    static func canonicalExtension(_ ext: String) -> String {
+        let lower = ext.lowercased()
+        return canonicalMap[lower] ?? lower
+    }
+
+    static func category(of url: URL) -> FileCategory {
+        if (try? url.resourceValues(forKeys: [.isDirectoryKey]).isDirectory) == true {
+            return .folder
+        }
+        return category(forExtension: url.pathExtension)
+    }
+
+    static func category(forExtension ext: String) -> FileCategory {
+        extensionMap[ext.lowercased()] ?? .unknown
+    }
+
+    static func format(of url: URL) -> Format? {
+        Format(rawValue: canonicalExtension(url.pathExtension))
+    }
+
+    static func isSupportedInput(_ url: URL) -> Bool {
+        category(of: url) != .unknown
+    }
+}
+
+/// What a wheel can offer for a given selection. Kept separate from the UI so
+/// the same table drives the drag wheel, the menu bar fallback and the
+/// Quick Action.
+enum ConversionCatalog {
+    static let targets: [FileCategory: [Format]] = [
+        .image: [.png, .jpg, .heic, .webp, .tiff, .bmp, .gif, .avif, .pdf],
+        .video: [.mp4, .mov, .mkv, .webm, .avi, .wmv, .gif, .mp3, .m4a, .wav],
+        .audio: [.mp3, .m4a, .wav, .flac, .ogg, .opus, .aiff, .wma],
+        .pdf: [.docx, .pptx, .xlsx, .jpg, .png, .epub, .txt, .md, .html],
+        .document: [.docx, .md, .txt, .rtf, .html, .epub, .pdf],
+        .slides: [.pdf, .jpg, .png],
+        .spreadsheet: [.xlsx, .ods, .csv, .tsv, .pdf],
+        .ebook: [.txt, .html, .md, .pdf],
+        .subtitle: [.srt, .vtt, .txt],
+        .archive: [.zip, .tar, .gzip]
+    ]
+
+    /// Outputs to show for a selection: the category's list minus the format
+    /// the file already is. A mixed selection falls back to the intersection.
+    static func outputs(for categories: [FileCategory]) -> [Format] {
+        let unique = Set(categories)
+        guard !unique.isEmpty, unique.count == 1, let category = unique.first else {
+            return []
+        }
+        return targets[category] ?? []
+    }
+
+    /// True when every input already has this extension (so it is pointless to
+    /// offer it).
+    static func isRedundant(_ format: Format, urls: [URL]) -> Bool {
+        guard !urls.isEmpty else { return false }
+        return urls.allSatisfy { FileKind.canonicalExtension($0.pathExtension) == format.ext }
+    }
+}
diff --git a/Sources/Konverter/Core/JobStore.swift b/Sources/Konverter/Core/JobStore.swift
new file mode 100644
index 0000000..8fbc167
--- /dev/null
+++ b/Sources/Konverter/Core/JobStore.swift
@@ -0,0 +1,285 @@
+import AppKit
+import Foundation
+
+enum JobTarget {
+    case format(Format)
+    case tool(ToolID)
+    case action(ActionID)
+}
+
+enum JobStatus {
+    case running
+    case finished
+    case failed
+    case cancelled
+
+    var isTerminal: Bool { self != .running }
+}
+
+struct Job: Identifiable {
+    let id = UUID()
+    var title: String
+    var detail: String = ""
+    var progress: Double = 0
+    var status: JobStatus = .running
+    var outputs: [URL] = []
+    var errorMessage: String?
+    var message: String?
+    var messageTitle: String?
+    var startedAt = Date()
+    var origin: CGPoint?
+    var target: JobTarget
+    var sourceCount: Int
+}
+
+/// Runs conversions off the main thread and publishes their state to the
+/// progress panel. Two jobs run at once; the queue keeps heavy video work from
+/// starving the UI.
+final class JobStore: ObservableObject {
+    static let shared = JobStore()
+
+    @Published private(set) var jobs: [Job] = []
+    @Published var panelVisible = false
+
+    private var tokens: [UUID: Cancellation] = [:]
+    private let queue: OperationQueue = {
+        let queue = OperationQueue()
+        queue.name = "dev.tzgyn.konverter.jobs"
+        queue.maxConcurrentOperationCount = 2
+        queue.qualityOfService = .userInitiated
+        return queue
+    }()
+
+    private init() {}
+
+    var activeCount: Int {
+        jobs.filter { !$0.status.isTerminal }.count
+    }
+
+    func submit(urls: [URL], target: JobTarget, params: ToolParams? = nil, origin: CGPoint? = nil) {
+        guard !urls.isEmpty else { return }
+        let token = Cancellation()
+        let job = Job(
+            title: title(for: target, urls: urls),
+            origin: origin,
+            target: target,
+            sourceCount: urls.count
+        )
+        jobs.append(job)
+        tokens[job.id] = token
+
+        if Settings.shared.showProgressWindow {
+            panelVisible = true
+            JobPanelController.shared.refresh(store: self)
+        }
+
+        queue.addOperation { [weak self] in
+            self?.execute(jobID: job.id, urls: urls, target: target, params: params, token: token)
+        }
+    }
+
+    func cancel(_ id: UUID) {
+        tokens[id]?.cancel()
+        mutate(id) { job in
+            if job.status == .running { job.detail = "Cancelling…" }
+        }
+    }
+
+    func cancelAll() {
+        for (id, token) in tokens {
+            token.cancel()
+            mutate(id) { job in
+                if job.status == .running { job.detail = "Cancelling…" }
+            }
+        }
+    }
+
+    func dismissFinished() {
+        jobs.removeAll { $0.status.isTerminal }
+        if jobs.isEmpty { panelVisible = false }
+        JobPanelController.shared.refresh(store: self)
+    }
+
+    func remove(_ id: UUID) {
+        jobs.removeAll { $0.id == id }
+        if jobs.isEmpty { panelVisible = false }
+        JobPanelController.shared.refresh(store: self)
+    }
+
+    // MARK: - Execution
+
+    private func execute(jobID: UUID, urls: [URL], target: JobTarget, params: ToolParams?, token: Cancellation) {
+        do {
+            switch target {
+            case .action(let action):
+                try performAction(action, urls: urls, token: token, jobID: jobID)
+
+            case .format(let format):
+                var outputs: [URL] = []
+                var firstError: Error?
+                for (index, url) in urls.enumerated() {
+                    try token.check()
+                    let destination = OutputNaming.destination(for: url, format: format)
+                    mutate(jobID) { job in
+                        job.detail = urls.count > 1 ? "\(url.lastPathComponent) → \(format.displayName)" : "Converting to \(format.displayName)"
+                    }
+                    do {
+                        let produced = try Converter.convert(
+                            source: url,
+                            to: format,
+                            at: destination,
+                            cancellation: token,
+                            progress: { [weak self] fraction in
+                                self?.setProgress(jobID, (Double(index) + fraction) / Double(urls.count))
+                            }
+                        )
+                        outputs.append(contentsOf: produced)
+                    } catch is CancellationError {
+                        throw CancellationError()
+                    } catch {
+                        if firstError == nil { firstError = error }
+                    }
+                }
+                if outputs.isEmpty, let firstError { throw firstError }
+                if let firstError {
+                    finish(jobID, outputs: outputs, error: firstError)
+                } else {
+                    finish(jobID, outputs: outputs, error: nil)
+                }
+
+            case .tool(let tool):
+                let resolved = params ?? Settings.shared.params(for: tool)
+                let outcome = try ToolRunner.run(
+                    tool: tool,
+                    inputs: urls,
+                    params: resolved,
+                    cancellation: token,
+                    progress: { [weak self] fraction in
+                        self?.setProgress(jobID, fraction)
+                    }
+                )
+                finish(jobID, outputs: outcome.outputs, error: nil, outcome: outcome)
+            }
+        } catch is CancellationError {
+            mutate(jobID) { job in
+                job.status = .cancelled
+                job.detail = "Cancelled"
+            }
+            tokens.removeValue(forKey: jobID)
+            DispatchQueue.main.async { JobPanelController.shared.refresh(store: self) }
+        } catch {
+            finish(jobID, outputs: [], error: error)
+        }
+    }
+
+    private func performAction(_ action: ActionID, urls: [URL], token: Cancellation, jobID: UUID) throws {
+        var failure: Error?
+        let ready = DispatchSemaphore(value: 0)
+        Task { @MainActor in
+            do {
+                try await FileActions.perform(action, urls: urls)
+            } catch {
+                failure = error
+            }
+            ready.signal()
+        }
+        ready.wait()
+        try token.check()
+        if let failure { throw failure }
+        mutate(jobID) { job in
+            job.detail = "Done"
+        }
+    }
+
+    // MARK: - State updates
+
+    private func title(for target: JobTarget, urls: [URL]) -> String {
+        let name = urls.count == 1
+            ? urls[0].lastPathComponent
+            : "\(urls.count) files"
+        switch target {
+        case .format(let format): return "\(name) → \(format.displayName)"
+        case .tool(let tool): return "\(tool.title) · \(name)"
+        case .action(let action): return "\(action.title) · \(name)"
+        }
+    }
+
+    private func setProgress(_ id: UUID, _ value: Double) {
+        mutate(id, throttle: true) { job in
+            job.progress = max(job.progress, min(1, value))
+        }
+    }
+
+    private func finish(_ id: UUID, outputs: [URL], error: Error?, outcome: ToolOutcome? = nil) {
+        tokens.removeValue(forKey: id)
+        mutate(id) { job in
+            job.outputs = outputs
+            job.progress = 1
+            if let error {
+                job.status = .failed
+                job.errorMessage = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
+                job.detail = "Failed"
+            } else {
+                job.status = .finished
+                job.detail = outputs.count > 1 ? "\(outputs.count) files" : "Done"
+                job.message = outcome?.message
+                job.messageTitle = outcome?.messageTitle
+            }
+        }
+
+        guard let job = jobs.first(where: { $0.id == id }) else { return }
+
+        if let error = job.errorMessage {
+            let title = job.title
+            DispatchQueue.main.async {
+                Notifier.error(title, error)
+            }
+        } else if let message = job.message {
+            let title = job.messageTitle ?? "Result"
+            DispatchQueue.main.async {
+                ResultWindowController.shared.show(title: title, body: message)
+            }
+        }
+
+        if Settings.shared.playSound, job.status == .finished, error == nil {
+            DispatchQueue.main.async {
+                NSSound(named: "Glass")?.play()
+            }
+        }
+
+        let revealable = job.outputs
+        if Settings.shared.revealWhenFinished, !revealable.isEmpty, error == nil {
+            DispatchQueue.main.async {
+                NSWorkspace.shared.activateFileViewerSelecting(revealable)
+                // The progress panel would otherwise stay on top of Finder.
+                JobPanelController.shared.dismissIfAllFinished(store: self)
+            }
+        } else {
+            DispatchQueue.main.async {
+                JobPanelController.shared.refresh(store: self)
+            }
+        }
+    }
+
+    /// Applies a mutation on the main thread; `throttle` skips updates that
+    /// would only nudge the progress bar by a hair.
+    private func mutate(_ id: UUID, throttle: Bool = false, _ body: @escaping (inout Job) -> Void) {
+        let apply = { [weak self] in
+            guard let self, let index = self.jobs.firstIndex(where: { $0.id == id }) else { return }
+            if throttle {
+                let before = self.jobs[index].progress
+                body(&self.jobs[index])
+                let after = self.jobs[index].progress
+                if abs(after - before) < 0.01, after < 1 { return }
+            } else {
+                body(&self.jobs[index])
+            }
+            JobPanelController.shared.refresh(store: self)
+        }
+        if Thread.isMainThread {
+            apply()
+        } else {
+            DispatchQueue.main.async(execute: apply)
+        }
+    }
+}
diff --git a/Sources/Konverter/Core/OutputNaming.swift b/Sources/Konverter/Core/OutputNaming.swift
new file mode 100644
index 0000000..d2cc962
--- /dev/null
+++ b/Sources/Konverter/Core/OutputNaming.swift
@@ -0,0 +1,66 @@
+import Foundation
+
+/// Where a produced file goes, and what it is called.
+enum OutputNaming {
+    /// ``name.pdf`` for ``photo.jpg`` — appends ``-2``, ``-3`` … when the
+    /// target already exists (unless the user asked to overwrite).
+    static func destination(for source: URL, format: Format, settings: Settings = .shared) -> URL {
+        let base = source.deletingPathExtension().lastPathComponent
+        let directory: URL
+        switch settings.outputLocation {
+        case .besideOriginal:
+            directory = source.deletingLastPathComponent()
+        case .chosenFolder:
+            let folder = settings.resolvedOutputFolder
+            directory = FileManager.default.fileExists(atPath: folder.path)
+                ? folder
+                : source.deletingLastPathComponent()
+        }
+        let candidate = directory.appendingPathComponent(base).appendingPathExtension(format.ext)
+        return settings.conflictPolicy == .overwrite ? candidate : availableURL(for: candidate)
+    }
+
+    /// A sibling of any output a tool produces (e.g. ``photo-compressed.jpg``).
+    static func sibling(for source: URL, suffix: String, extension ext: String? = nil) -> URL {
+        let base = source.deletingPathExtension().lastPathComponent
+        let directory = source.deletingLastPathComponent()
+        let resolvedExtension = ext ?? source.pathExtension
+        return availableURL(
+            for: directory.appendingPathComponent(base + suffix).appendingPathExtension(resolvedExtension)
+        )
+    }
+
+    /// A working directory for multi-file outputs (split pages, extracted
+    /// images, unarchived trees).
+    static func artifactDirectory(for source: URL, suffix: String) -> URL {
+        let base = source.deletingPathExtension().lastPathComponent
+        let directory = source.deletingLastPathComponent()
+        let url = directory.appendingPathComponent(base + suffix, isDirectory: true)
+        var candidate = url
+        var index = 2
+        while FileManager.default.fileExists(atPath: candidate.path) {
+            candidate = directory.appendingPathComponent("\(base + suffix) \(index)", isDirectory: true)
+            index += 1
+        }
+        return candidate
+    }
+
+    /// ``foo 2.txt``, ``foo 3.txt`` … until the name is free.
+    static func availableURL(for url: URL) -> URL {
+        guard FileManager.default.fileExists(atPath: url.path) else { return url }
+        let directory = url.deletingLastPathComponent()
+        let ext = url.pathExtension
+        let base = url.deletingPathExtension().lastPathComponent
+        var index = 2
+        while true {
+            let name = ext.isEmpty ? "\(base) \(index)" : "\(base) \(index).\(ext)"
+            let candidate = directory.appendingPathComponent(name)
+            if !FileManager.default.fileExists(atPath: candidate.path) { return candidate }
+            index += 1
+        }
+    }
+
+    static func uniqueChild(of directory: URL, suggestedName: String) -> URL {
+        availableURL(for: directory.appendingPathComponent(suggestedName))
+    }
+}
diff --git a/Sources/Konverter/Core/Settings.swift b/Sources/Konverter/Core/Settings.swift
new file mode 100644
index 0000000..4365837
--- /dev/null
+++ b/Sources/Konverter/Core/Settings.swift
@@ -0,0 +1,201 @@
+import AppKit
+import Foundation
+import ServiceManagement
+
+/// Trigger keys. Tangerine's split: Shift converts, Command fills the wheel
+/// with file tools, Control with file actions.
+enum TriggerKey: String, CaseIterable, Identifiable, Codable {
+    case shift, control, option, command, function
+
+    var id: String { rawValue }
+
+    var title: String {
+        switch self {
+        case .shift: return "Shift ⇧"
+        case .control: return "Control ⌃"
+        case .option: return "Option ⌥"
+        case .command: return "Command ⌘"
+        case .function: return "Function fn"
+        }
+    }
+
+    var flag: NSEvent.ModifierFlags {
+        switch self {
+        case .shift: return .shift
+        case .control: return .control
+        case .option: return .option
+        case .command: return .command
+        case .function: return .function
+        }
+    }
+}
+
+enum OutputLocation: String, CaseIterable, Identifiable, Codable {
+    case besideOriginal, chosenFolder
+
+    var id: String { rawValue }
+    var title: String {
+        switch self {
+        case .besideOriginal: return "Beside the original"
+        case .chosenFolder: return "In a folder I choose"
+        }
+    }
+}
+
+enum ConflictPolicy: String, CaseIterable, Identifiable, Codable {
+    case uniqueName, overwrite
+
+    var id: String { rawValue }
+    var title: String {
+        switch self {
+        case .uniqueName: return "Keep both (add a number)"
+        case .overwrite: return "Replace the existing file"
+        }
+    }
+}
+
+enum WheelStyle: String, CaseIterable, Identifiable, Codable {
+    case radial, list
+
+    var id: String { rawValue }
+    var title: String {
+        switch self {
+        case .radial: return "Wheel"
+        case .list: return "List"
+        }
+    }
+}
+
+/// All preferences. Stored in `UserDefaults` under `konverter.*` so the app
+/// stays a single self-contained bundle with no sandbox container.
+final class Settings: ObservableObject {
+    static let shared = Settings()
+
+    private let defaults = UserDefaults.standard
+
+    @Published var convertKey: TriggerKey { didSet { write(convertKey, .convertKey) } }
+    @Published var toolsKey: TriggerKey { didSet { write(toolsKey, .toolsKey) } }
+    @Published var actionsKey: TriggerKey { didSet { write(actionsKey, .actionsKey) } }
+
+    /// When on, the tools wheel needs Shift + toolsKey so a plain ⌘-drag in
+    /// other apps does not pop the wheel.
+    @Published var requireShiftForTools: Bool { didSet { write(requireShiftForTools, .requireShiftForTools) } }
+
+    @Published var enabled: Bool { didSet { write(enabled, .enabled) } }
+    @Published var allowActionsOnFolders: Bool { didSet { write(allowActionsOnFolders, .allowActionsOnFolders) } }
+
+    @Published var outputLocation: OutputLocation { didSet { write(outputLocation.rawValue, .outputLocation) } }
+    @Published var outputFolderPath: String { didSet { write(outputFolderPath, .outputFolderPath) } }
+    @Published var conflictPolicy: ConflictPolicy { didSet { write(conflictPolicy.rawValue, .conflictPolicy) } }
+
+    @Published var wheelStyle: WheelStyle { didSet { write(wheelStyle.rawValue, .wheelStyle) } }
+    @Published var wheelRadius: Double { didSet { write(wheelRadius, .wheelRadius) } }
+    @Published var showLabels: Bool { didSet { write(showLabels, .showLabels) } }
+    @Published var dimBackground: Bool { didSet { write(dimBackground, .dimBackground) } }
+
+    @Published var showProgressWindow: Bool { didSet { write(showProgressWindow, .showProgressWindow) } }
+    @Published var revealWhenFinished: Bool { didSet { write(revealWhenFinished, .revealWhenFinished) } }
+    @Published var playSound: Bool { didSet { write(playSound, .playSound) } }
+    @Published var useExternalTools: Bool { didSet { write(useExternalTools, .useExternalTools) } }
+
+    @Published var openAtLogin: Bool { didSet { write(openAtLogin, .openAtLogin) } }
+
+    /// Remembers per-tool form values so repeat jobs are still one drop.
+    private var toolParamsCache: [String: [String: String]] = [:]
+
+    private init() {
+        convertKey = Settings.read(.convertKey, default: .shift)
+        toolsKey = Settings.read(.toolsKey, default: .command)
+        actionsKey = Settings.read(.actionsKey, default: .control)
+        requireShiftForTools = Settings.readBool(.requireShiftForTools, default: true)
+        enabled = Settings.readBool(.enabled, default: true)
+        allowActionsOnFolders = Settings.readBool(.allowActionsOnFolders, default: true)
+        outputLocation = Settings.read(.outputLocation, default: .besideOriginal)
+        outputFolderPath = Settings.readString(.outputFolderPath, default: "")
+        conflictPolicy = Settings.read(.conflictPolicy, default: .uniqueName)
+        wheelStyle = Settings.read(.wheelStyle, default: .radial)
+        wheelRadius = Settings.readDouble(.wheelRadius, default: 168)
+        showLabels = Settings.readBool(.showLabels, default: true)
+        dimBackground = Settings.readBool(.dimBackground, default: false)
+        showProgressWindow = Settings.readBool(.showProgressWindow, default: true)
+        revealWhenFinished = Settings.readBool(.revealWhenFinished, default: true)
+        playSound = Settings.readBool(.playSound, default: true)
+        useExternalTools = Settings.readBool(.useExternalTools, default: true)
+        openAtLogin = LoginItem.isEnabled
+    }
+
+    var resolvedOutputFolder: URL {
+        if outputLocation == .chosenFolder, !outputFolderPath.isEmpty {
+            return URL(fileURLWithPath: outputFolderPath)
+        }
+        return FileManager.default.homeDirectoryForCurrentUser
+    }
+
+    // MARK: - Tool parameter memory
+
+    func params(for tool: ToolID) -> ToolParams {
+        var params = ToolParams.defaults(for: tool)
+        if let stored = toolParamsCache[tool.rawValue] {
+            for (key, value) in stored { params[key] = value }
+        }
+        return params
+    }
+
+    func store(params: ToolParams, for tool: ToolID) {
+        toolParamsCache[tool.rawValue] = params.dictionary
+    }
+
+    // MARK: - Persistence
+
+    private enum Key: String {
+        case convertKey, toolsKey, actionsKey, requireShiftForTools, enabled, allowActionsOnFolders
+        case outputLocation, outputFolderPath, conflictPolicy
+        case wheelStyle, wheelRadius, showLabels, dimBackground
+        case showProgressWindow, revealWhenFinished, playSound, useExternalTools, openAtLogin
+    }
+
+    private func write<T>(_ value: T, _ key: Key) {
+        defaults.set(value, forKey: "konverter." + key.rawValue)
+    }
+
+    private static func read<T: RawRepresentable>(_ key: Key, default fallback: T) -> T where T.RawValue == String {
+        guard let raw = UserDefaults.standard.string(forKey: "konverter." + key.rawValue),
+              let value = T(rawValue: raw) else { return fallback }
+        return value
+    }
+
+    private static func readString(_ key: Key, default fallback: String) -> String {
+        UserDefaults.standard.string(forKey: "konverter." + key.rawValue) ?? fallback
+    }
+
+    private static func readBool(_ key: Key, default fallback: Bool) -> Bool {
+        guard UserDefaults.standard.object(forKey: "konverter." + key.rawValue) != nil else { return fallback }
+        return UserDefaults.standard.bool(forKey: "konverter." + key.rawValue)
+    }
+
+    private static func readDouble(_ key: Key, default fallback: Double) -> Double {
+        guard UserDefaults.standard.object(forKey: "konverter." + key.rawValue) != nil else { return fallback }
+        return UserDefaults.standard.double(forKey: "konverter." + key.rawValue)
+    }
+}
+
+enum LoginItem {
+    static var isEnabled: Bool {
+        SMAppService.mainApp.status == .enabled
+    }
+
+    @discardableResult
+    static func set(_ enabled: Bool) -> Bool {
+        let service = SMAppService.mainApp
+        do {
+            if enabled {
+                if service.status != .enabled { try service.register() }
+            } else {
+                if service.status == .enabled { try service.unregister() }
+            }
+            return true
+        } catch {
+            return false
+        }
+    }
+}
diff --git a/Sources/Konverter/Core/Shell.swift b/Sources/Konverter/Core/Shell.swift
new file mode 100644
index 0000000..d418d88
--- /dev/null
+++ b/Sources/Konverter/Core/Shell.swift
@@ -0,0 +1,256 @@
+import Foundation
+
+/// A cooperative cancellation token shared between a job and the external
+/// processes it spawns. Converters run off the main thread, so every mutation
+/// is lock protected.
+final class Cancellation {
+    private let lock = NSLock()
+    private var cancelled = false
+    private var processes: [Process] = []
+
+    var isCancelled: Bool {
+        lock.lock()
+        defer { lock.unlock() }
+        return cancelled
+    }
+
+    func cancel() {
+        lock.lock()
+        cancelled = true
+        let running = processes
+        lock.unlock()
+        for process in running where process.isRunning {
+            process.terminate()
+        }
+    }
+
+    func register(_ process: Process) {
+        lock.lock()
+        let alreadyCancelled = cancelled
+        if !alreadyCancelled { processes.append(process) }
+        lock.unlock()
+        if alreadyCancelled, process.isRunning { process.terminate() }
+    }
+
+    func check() throws {
+        if isCancelled { throw CancellationError() }
+    }
+}
+
+struct ShellError: LocalizedError {
+    let command: String
+    let status: Int32
+    let stderr: String
+
+    var errorDescription: String? {
+        let detail = stderr.trimmingCharacters(in: .whitespacesAndNewlines)
+        if detail.isEmpty {
+            return "\(command) exited with status \(status)."
+        }
+        // External tools can be very chatty; keep the first meaningful line.
+        let line = detail
+            .split(separator: "\n")
+            .map { $0.trimmingCharacters(in: .whitespaces) }
+            .last { !$0.isEmpty } ?? detail
+        return "\(command): \(line.prefix(400))"
+    }
+}
+
+/// Thin wrapper around `Process` with deadlock-free pipe draining.
+enum Shell {
+    struct Result {
+        let status: Int32
+        let stdout: String
+        let stderr: String
+    }
+
+    private final class Box<T> {
+        var value: T
+        init(_ value: T) { self.value = value }
+    }
+
+    /// Locate an executable by name, searching `extraPaths` first and then
+    /// `$PATH`. Returns the last match so Homebrew's copies win over system
+    /// stubs (e.g. the `/usr/bin/ffmpeg` shim that only opens the App Store).
+    static func find(_ name: String, extraPaths: [String] = []) -> String? {
+        var search = extraPaths
+        if let path = ProcessInfo.processInfo.environment["PATH"] {
+            search += path.split(separator: ":").map(String.init)
+        }
+        var found: String?
+        for directory in search {
+            let full = directory.hasSuffix("/") ? directory + name : directory + "/" + name
+            if FileManager.default.isExecutableFile(atPath: full) {
+                found = full
+            }
+        }
+        return found
+    }
+
+    @discardableResult
+    static func run(
+        _ executable: String,
+        _ arguments: [String],
+        currentDirectory: URL? = nil,
+        cancellation: Cancellation? = nil
+    ) throws -> Result {
+        try cancellation?.check()
+
+        let process = Process()
+        process.executableURL = URL(fileURLWithPath: executable)
+        process.arguments = arguments
+        if let currentDirectory { process.currentDirectoryURL = currentDirectory }
+
+        let outPipe = Pipe()
+        let errPipe = Pipe()
+        process.standardOutput = outPipe
+        process.standardError = errPipe
+        process.standardInput = FileHandle.nullDevice
+
+        do {
+            try process.run()
+        } catch {
+            throw ShellError(
+                command: (arguments.first ?? executable),
+                status: -1,
+                stderr: error.localizedDescription
+            )
+        }
+        cancellation?.register(process)
+
+        // Drain both pipes on separate queues: reading them in sequence can
+        // deadlock when a tool fills the buffer we are not reading yet.
+        let outBox = Box(Data())
+        let errBox = Box(Data())
+        let group = DispatchGroup()
+        DispatchQueue.global(qos: .utility).async(group: group) {
+            outBox.value = (try? outPipe.fileHandleForReading.readToEnd()) ?? Data()
+        }
+        DispatchQueue.global(qos: .utility).async(group: group) {
+            errBox.value = (try? errPipe.fileHandleForReading.readToEnd()) ?? Data()
+        }
+        group.wait()
+        process.waitUntilExit()
+
+        let result = Result(
+            status: process.terminationStatus,
+            stdout: String(data: outBox.value, encoding: .utf8) ?? "",
+            stderr: String(data: errBox.value, encoding: .utf8) ?? ""
+        )
+
+        try cancellation?.check()
+        if result.status != 0 {
+            throw ShellError(
+                command: (arguments.first ?? executable),
+                status: result.status,
+                stderr: result.stderr.isEmpty ? result.stdout : result.stderr
+            )
+        }
+        return result
+    }
+
+    /// Best-effort variant used for optional probes (`ffprobe`, `mdls`, …).
+    static func output(_ executable: String, _ arguments: [String]) -> String? {
+        (try? run(executable, arguments))?.stdout
+    }
+
+    /// Runs a tool whose stdout is binary (compressed streams) and returns it.
+    static func runData(
+        _ executable: String,
+        _ arguments: [String],
+        cancellation: Cancellation? = nil
+    ) throws -> Data {
+        try cancellation?.check()
+
+        let process = Process()
+        process.executableURL = URL(fileURLWithPath: executable)
+        process.arguments = arguments
+        let outPipe = Pipe()
+        let errPipe = Pipe()
+        process.standardOutput = outPipe
+        process.standardError = errPipe
+        process.standardInput = FileHandle.nullDevice
+
+        do {
+            try process.run()
+        } catch {
+            throw ShellError(command: arguments.first ?? executable, status: -1, stderr: error.localizedDescription)
+        }
+        cancellation?.register(process)
+
+        let outBox = Box(Data())
+        let errBox = Box(Data())
+        let group = DispatchGroup()
+        DispatchQueue.global(qos: .utility).async(group: group) {
+            outBox.value = (try? outPipe.fileHandleForReading.readToEnd()) ?? Data()
+        }
+        DispatchQueue.global(qos: .utility).async(group: group) {
+            errBox.value = (try? errPipe.fileHandleForReading.readToEnd()) ?? Data()
+        }
+        group.wait()
+        process.waitUntilExit()
+
+        let stderr = String(data: errBox.value, encoding: .utf8) ?? ""
+        try cancellation?.check()
+        if process.terminationStatus != 0 {
+            throw ShellError(command: arguments.first ?? executable, status: process.terminationStatus, stderr: stderr)
+        }
+        return outBox.value
+    }
+
+    /// Runs a tool and reports progress parsed from `key=value` lines on
+    /// stdout (what `ffmpeg -progress pipe:1` emits).
+    static func runReportingProgress(
+        _ executable: String,
+        _ arguments: [String],
+        cancellation: Cancellation? = nil,
+        onProgress: @escaping (Double, String) -> Void
+    ) throws {
+        try cancellation?.check()
+
+        let process = Process()
+        process.executableURL = URL(fileURLWithPath: executable)
+        process.arguments = arguments
+        let outPipe = Pipe()
+        let errPipe = Pipe()
+        process.standardOutput = outPipe
+        process.standardError = errPipe
+        process.standardInput = FileHandle.nullDevice
+
+        let errBox = Box(Data())
+        DispatchQueue.global(qos: .utility).async {
+            errBox.value = (try? errPipe.fileHandleForReading.readToEnd()) ?? Data()
+        }
+
+        let buffer = Box(Data())
+        let lock = NSLock()
+        outPipe.fileHandleForReading.readabilityHandler = { handle in
+            let chunk = handle.availableData
+            guard !chunk.isEmpty else { return }
+            lock.lock()
+            buffer.value.append(chunk)
+            let text = String(data: buffer.value, encoding: .utf8) ?? ""
+            var lines = text.split(separator: "\n", omittingEmptySubsequences: false).map(String.init)
+            let remainder = lines.popLast() ?? ""
+            buffer.value = Data(remainder.utf8)
+            lock.unlock()
+            for line in lines { onProgress(0, line) }
+        }
+
+        do {
+            try process.run()
+        } catch {
+            outPipe.fileHandleForReading.readabilityHandler = nil
+            throw ShellError(command: arguments.first ?? executable, status: -1, stderr: error.localizedDescription)
+        }
+        cancellation?.register(process)
+        process.waitUntilExit()
+        outPipe.fileHandleForReading.readabilityHandler = nil
+
+        let stderr = String(data: errBox.value, encoding: .utf8) ?? ""
+        try cancellation?.check()
+        if process.terminationStatus != 0 {
+            throw ShellError(command: arguments.first ?? executable, status: process.terminationStatus, stderr: stderr)
+        }
+    }
+}
diff --git a/Sources/Konverter/Core/Toolchain.swift b/Sources/Konverter/Core/Toolchain.swift
new file mode 100644
index 0000000..5f9a899
--- /dev/null
+++ b/Sources/Konverter/Core/Toolchain.swift
@@ -0,0 +1,55 @@
+import Foundation
+
+/// Optional external helpers. Konverter works without them — they only widen
+/// the conversion matrix (formats Apple's frameworks cannot write) and are
+/// detected once at launch.
+enum Toolchain {
+    private static let homebrewPaths = ["/opt/homebrew/bin", "/usr/local/bin"]
+
+    /// ffmpeg/ffprobe: MKV, WebM, AVI, WMV, MP3, FLAC, OGG, Opus, WMA.
+    static let ffmpeg: String? = Shell.find("ffmpeg", extraPaths: homebrewPaths)
+    static let ffprobe: String? = Shell.find("ffprobe", extraPaths: homebrewPaths)
+
+    /// LibreOffice: PPT/PPTX rendering, XLS/XLSX/ODS, PAGES, Keynote.
+    static let soffice: String? = {
+        let candidates = [
+            "/Applications/LibreOffice.app/Contents/MacOS/soffice",
+            "/Applications/LibreOffice.app/Contents/MacOS/soffice.bin"
+        ]
+        for candidate in candidates where FileManager.default.isExecutableFile(atPath: candidate) {
+            return candidate
+        }
+        return Shell.find("soffice", extraPaths: homebrewPaths)
+    }()
+
+    static var hasFFmpeg: Bool { ffmpeg != nil }
+    static var hasLibreOffice: Bool { soffice != nil }
+
+    /// `curl`-free, sandbox-free best-effort image rasteriser for SVG and other
+    /// formats ImageIO refuses to decode but Quick Look understands.
+    static let qlmanage: String? = Shell.find("qlmanage", extraPaths: ["/usr/bin"])
+
+    static let ditto = "/usr/bin/ditto"
+    static let tar = "/usr/bin/tar"
+    static let gzip = "/usr/bin/gzip"
+    static let gunzip = "/usr/bin/gunzip"
+    static let textutil = "/usr/bin/textutil"
+    static let afconvert = "/usr/bin/afconvert"
+    static let zip = "/usr/bin/zip"
+    static let unzip = "/usr/bin/unzip"
+
+    /// Human readable summary for the About/Settings pane.
+    static var summary: String {
+        var parts: [String] = ["Core (ImageIO, PDFKit, AVFoundation)"]
+        if hasFFmpeg { parts.append("ffmpeg") }
+        if hasLibreOffice { parts.append("LibreOffice") }
+        return parts.joined(separator: " · ")
+    }
+
+    static var missingToolAdvice: String? {
+        var advice: [String] = []
+        if !hasFFmpeg { advice.append("brew install ffmpeg") }
+        if !hasLibreOffice { advice.append("brew install --cask libreoffice") }
+        return advice.isEmpty ? nil : advice.joined(separator: "  ·  ")
+    }
+}
diff --git a/Sources/Konverter/Core/Tools.swift b/Sources/Konverter/Core/Tools.swift
new file mode 100644
index 0000000..ef35d60
--- /dev/null
+++ b/Sources/Konverter/Core/Tools.swift
@@ -0,0 +1,333 @@
+import Foundation
+
+/// A tool: an in-place transform that is not a plain format change.
+enum ToolID: String, CaseIterable, Identifiable, Codable {
+    // Images
+    case compressImage, resizeImage, cropImage, rotateImage, flipImage
+    case grayscaleImage, stripMetadata, watermarkImage, readQR
+    // Video
+    case compressVideo, trimVideo, muteVideo, speedVideo, snapshotVideo
+    case videoToGIF, resizeVideo
+    // Audio
+    case trimAudio, normalizeAudio, channelsAudio, speedAudio, bleepAudio, compressAudio
+    // PDF
+    case mergePDF, splitPDF, rotatePDF, compressPDF, encryptPDF, decryptPDF
+    case imagesToPDF, collageImages, extractPDFText
+    // Documents
+    case documentToPDF, wordCount
+    // Spreadsheets
+    case sheetsToCSV
+    // Subtitles
+    case shiftSubtitle
+    // Archives
+    case extractArchive, listArchive
+    // Media metadata
+    case mediaInfo
+
+    var id: String { rawValue }
+
+    var title: String {
+        switch self {
+        case .compressImage: return "Compress"
+        case .resizeImage: return "Resize"
+        case .cropImage: return "Crop"
+        case .rotateImage: return "Rotate"
+        case .flipImage: return "Flip"
+        case .grayscaleImage: return "Grayscale"
+        case .stripMetadata: return "Strip Metadata"
+        case .watermarkImage: return "Watermark"
+        case .readQR: return "Read QR"
+        case .compressVideo: return "Compress"
+        case .trimVideo: return "Trim"
+        case .muteVideo: return "Mute"
+        case .speedVideo: return "Speed"
+        case .snapshotVideo: return "Snapshot"
+        case .videoToGIF: return "To GIF"
+        case .resizeVideo: return "Resize"
+        case .trimAudio: return "Trim"
+        case .normalizeAudio: return "Normalize"
+        case .channelsAudio: return "Channels"
+        case .speedAudio: return "Speed"
+        case .bleepAudio: return "Bleep"
+        case .compressAudio: return "Compress"
+        case .mergePDF: return "Merge"
+        case .splitPDF: return "Split"
+        case .rotatePDF: return "Rotate"
+        case .compressPDF: return "Compress"
+        case .encryptPDF: return "Encrypt"
+        case .decryptPDF: return "Decrypt"
+        case .imagesToPDF: return "Images to PDF"
+        case .collageImages: return "Collage"
+        case .extractPDFText: return "Extract Text"
+        case .documentToPDF: return "To PDF"
+        case .wordCount: return "Statistics"
+        case .sheetsToCSV: return "To CSV"
+        case .shiftSubtitle: return "Shift Time"
+        case .extractArchive: return "Extract"
+        case .listArchive: return "List Contents"
+        case .mediaInfo: return "Info"
+        }
+    }
+
+    var symbol: String {
+        switch self {
+        case .compressImage, .compressVideo, .compressAudio, .compressPDF: return "arrow.down.right.and.arrow.up.left"
+        case .resizeImage, .resizeVideo: return "arrow.up.left.and.arrow.down.right"
+        case .cropImage: return "crop"
+        case .rotateImage, .rotatePDF: return "rotate.right"
+        case .flipImage: return "arrow.left.and.right.righttriangle.left.righttriangle.right"
+        case .grayscaleImage: return "circle.lefthalf.filled"
+        case .stripMetadata, .mediaInfo: return "info.circle"
+        case .watermarkImage: return "signature"
+        case .readQR: return "qrcode.viewfinder"
+        case .trimVideo, .trimAudio: return "scissors"
+        case .muteVideo, .bleepAudio: return "speaker.slash"
+        case .speedVideo, .speedAudio: return "gauge.with.dots.needle.67percent"
+        case .snapshotVideo: return "camera"
+        case .videoToGIF: return "rectangle.stack"
+        case .normalizeAudio: return "waveform.path.ecg"
+        case .channelsAudio: return "speaker.wave.2"
+        case .mergePDF: return "square.stack.3d.down.right"
+        case .splitPDF: return "scissors"
+        case .encryptPDF: return "lock"
+        case .decryptPDF: return "lock.open"
+        case .imagesToPDF: return "doc.badge.plus"
+        case .collageImages: return "rectangle.grid.2x2"
+        case .extractPDFText: return "text.viewfinder"
+        case .documentToPDF: return "doc.richtext"
+        case .wordCount: return "number"
+        case .sheetsToCSV: return "tablecells.badge.ellipsis"
+        case .shiftSubtitle: return "clock.arrow.circlepath"
+        case .extractArchive: return "archivebox"
+        case .listArchive: return "list.bullet.rectangle"
+        }
+    }
+
+    var category: FileCategory {
+        switch self {
+        case .compressImage, .resizeImage, .cropImage, .rotateImage, .flipImage,
+             .grayscaleImage, .stripMetadata, .watermarkImage, .readQR:
+            return .image
+        case .compressVideo, .trimVideo, .muteVideo, .speedVideo, .snapshotVideo,
+             .videoToGIF, .resizeVideo:
+            return .video
+        case .trimAudio, .normalizeAudio, .channelsAudio, .speedAudio, .bleepAudio, .compressAudio:
+            return .audio
+        case .mergePDF, .splitPDF, .rotatePDF, .compressPDF, .encryptPDF, .decryptPDF,
+             .imagesToPDF, .collageImages, .extractPDFText:
+            return .pdf
+        case .documentToPDF, .wordCount:
+            return .document
+        case .sheetsToCSV:
+            return .spreadsheet
+        case .shiftSubtitle:
+            return .subtitle
+        case .extractArchive, .listArchive:
+            return .archive
+        case .mediaInfo:
+            return .video
+        }
+    }
+
+    /// Tools that only make sense for a multi-file selection.
+    var requiresMultipleFiles: Bool {
+        self == .mergePDF || self == .imagesToPDF || self == .collageImages
+    }
+
+    var minimumFileCount: Int { requiresMultipleFiles ? 2 : 1 }
+
+    /// Tools that produce a derived file instead of a transformed copy.
+    var producesArtifacts: Bool {
+        switch self {
+        case .readQR, .extractPDFText, .listArchive, .mediaInfo, .wordCount:
+            return true
+        default:
+            return false
+        }
+    }
+
+    /// Some tools can only work on narrower inputs (PDF tools on PDFs already,
+    /// video-only tools on video).
+    static func tools(for category: FileCategory) -> [ToolID] {
+        allCases.filter { $0.category == category }
+    }
+}
+
+/// One editable field in a tool's options form.
+struct ToolField: Identifiable, Hashable {
+    enum Kind: Hashable {
+        case text
+        case secret
+        case integer(min: Int, max: Int)
+        case decimal(min: Double, max: Double)
+        case toggle
+        case choice([String])
+        case timecode
+    }
+
+    let id: String
+    let label: String
+    let kind: Kind
+    let defaultValue: String
+    let unit: String?
+    let help: String?
+
+    init(_ id: String, _ label: String, _ kind: Kind, default value: String, unit: String? = nil, help: String? = nil) {
+        self.id = id
+        self.label = label
+        self.kind = kind
+        self.defaultValue = value
+        self.unit = unit
+        self.help = help
+    }
+}
+
+extension ToolID {
+    var fields: [ToolField] {
+        switch self {
+        case .compressImage:
+            return [ToolField("quality", "Quality", .integer(min: 1, max: 100), default: "70", unit: "%")]
+        case .resizeImage:
+            return [
+                ToolField("width", "Max width", .integer(min: 16, max: 20000), default: "1920", unit: "px"),
+                ToolField("height", "Max height", .integer(min: 16, max: 20000), default: "1920", unit: "px"),
+                ToolField("percent", "…or scale", .integer(min: 1, max: 400), default: "100", unit: "%")
+            ]
+        case .cropImage:
+            return [
+                ToolField("inset", "Inset from each edge", .integer(min: 0, max: 4000), default: "0", unit: "px"),
+                ToolField("aspect", "Aspect", .choice(["Keep", "1:1", "4:3", "3:2", "16:9", "9:16"]), default: "Keep")
+            ]
+        case .rotateImage, .rotatePDF:
+            return [ToolField("angle", "Rotation", .choice(["90° right", "180°", "90° left"]), default: "90° right")]
+        case .flipImage:
+            return [ToolField("axis", "Axis", .choice(["Horizontal", "Vertical"]), default: "Horizontal")]
+        case .watermarkImage:
+            return [
+                ToolField("text", "Text", .text, default: "©"),
+                ToolField("position", "Position", .choice(["Bottom Right", "Bottom Left", "Top Right", "Top Left", "Center"]), default: "Bottom Right"),
+                ToolField("opacity", "Opacity", .integer(min: 5, max: 100), default: "45", unit: "%"),
+                ToolField("size", "Size", .integer(min: 8, max: 40), default: "16", unit: "% of width")
+            ]
+        case .compressVideo:
+            return [ToolField("preset", "Quality", .choice(["Low", "Medium", "High"]), default: "Medium")]
+        case .trimVideo, .trimAudio:
+            return [
+                ToolField("start", "Start", .timecode, default: "00:00:00"),
+                ToolField("end", "End", .timecode, default: "", help: "Leave empty to keep the tail")
+            ]
+        case .speedVideo, .speedAudio:
+            return [ToolField("rate", "Speed", .decimal(min: 0.25, max: 4), default: "2", unit: "×")]
+        case .snapshotVideo:
+            return [ToolField("at", "Timestamp", .timecode, default: "00:00:01")]
+        case .videoToGIF:
+            return [
+                ToolField("fps", "Frame rate", .integer(min: 5, max: 30), default: "12", unit: "fps"),
+                ToolField("width", "Width", .integer(min: 120, max: 1600), default: "480", unit: "px")
+            ]
+        case .resizeVideo:
+            return [ToolField("width", "Width", .integer(min: 160, max: 7680), default: "1280", unit: "px")]
+        case .bleepAudio:
+            return [
+                ToolField("start", "Mute from", .timecode, default: "00:00:00"),
+                ToolField("end", "Mute until", .timecode, default: "00:00:01")
+            ]
+        case .compressAudio:
+            return [ToolField("bitrate", "Bitrate", .choice(["64", "96", "128", "192", "256", "320"]), default: "128", unit: "kbps")]
+        case .channelsAudio:
+            return [ToolField("mode", "Channels", .choice(["Mono", "Stereo"]), default: "Mono")]
+        case .splitPDF:
+            return [ToolField("pages", "Pages per file", .integer(min: 1, max: 500), default: "1")]
+        case .compressPDF:
+            return [ToolField("quality", "Image quality", .integer(min: 10, max: 100), default: "55", unit: "%")]
+        case .encryptPDF:
+            return [
+                ToolField("password", "Password", .secret, default: ""),
+                ToolField("owner", "Owner password", .secret, default: "", help: "Optional, defaults to the password")
+            ]
+        case .decryptPDF:
+            return [ToolField("password", "Password", .secret, default: "")]
+        case .collageImages:
+            return [
+                ToolField("columns", "Columns", .integer(min: 1, max: 8), default: "3"),
+                ToolField("page", "Page", .choice(["A4", "Letter", "Square"]), default: "A4"),
+                ToolField("margin", "Margin", .integer(min: 0, max: 120), default: "24", unit: "pt"),
+                ToolField("captions", "File names", .toggle, default: "false")
+            ]
+        case .shiftSubtitle:
+            return [ToolField("offset", "Shift by", .decimal(min: -600, max: 600), default: "1", unit: "s")]
+        case .listArchive, .extractArchive, .wordCount, .mediaInfo, .readQR, .stripMetadata,
+             .grayscaleImage, .normalizeAudio, .extractPDFText, .documentToPDF, .sheetsToCSV,
+             .muteVideo, .mergePDF, .imagesToPDF:
+            return []
+        }
+    }
+}
+
+/// Values collected from a tool's options form. Round-trips through
+/// `UserDefaults` per tool so repeat use is one drop.
+struct ToolParams {
+    private var storage: [String: String] = [:]
+
+    subscript(key: String) -> String? {
+        get { storage[key] }
+        set { storage[key] = newValue }
+    }
+
+    func string(_ key: String, default fallback: String = "") -> String {
+        let value = storage[key]?.trimmingCharacters(in: .whitespaces) ?? ""
+        return value.isEmpty ? fallback : value
+    }
+
+    func int(_ key: String, default fallback: Int) -> Int {
+        Int(string(key)) ?? fallback
+    }
+
+    func double(_ key: String, default fallback: Double) -> Double {
+        Double(string(key)) ?? fallback
+    }
+
+    func bool(_ key: String, default fallback: Bool) -> Bool {
+        guard let value = storage[key] else { return fallback }
+        return value == "true" || value == "1"
+    }
+
+    static func defaults(for tool: ToolID) -> ToolParams {
+        var params = ToolParams()
+        for field in tool.fields {
+            params[field.id] = field.defaultValue
+        }
+        return params
+    }
+
+    mutating func fillMissing(from tool: ToolID) {
+        for field in tool.fields where storage[field.id] == nil {
+            storage[field.id] = field.defaultValue
+        }
+    }
+
+    var isEmpty: Bool { storage.isEmpty }
+
+    var dictionary: [String: String] { storage }
+}
+
+/// Timecodes come in as `mm:ss`, `hh:mm:ss` or plain seconds.
+enum Timecode {
+    static func seconds(from string: String) -> Double? {
+        let trimmed = string.trimmingCharacters(in: .whitespaces)
+        if trimmed.isEmpty { return nil }
+        let parts = trimmed.split(separator: ":").map(String.init)
+        switch parts.count {
+        case 1:
+            return Double(parts[0])
+        case 2:
+            guard let minutes = Double(parts[0]), let seconds = Double(parts[1]) else { return nil }
+            return minutes * 60 + seconds
+        case 3:
+            guard let h = Double(parts[0]), let m = Double(parts[1]), let s = Double(parts[2]) else { return nil }
+            return h * 3600 + m * 60 + s
+        default:
+            return nil
+        }
+    }
+}
diff --git a/Sources/Konverter/Core/WheelOption.swift b/Sources/Konverter/Core/WheelOption.swift
new file mode 100644
index 0000000..6df3c98
--- /dev/null
+++ b/Sources/Konverter/Core/WheelOption.swift
@@ -0,0 +1,141 @@
+import AppKit
+import Foundation
+
+/// One wedge of the wheel.
+struct WheelItem: Identifiable {
+    enum Payload {
+        case format(Format)
+        case tool(ToolID)
+        case action(ActionID)
+    }
+
+    let id: String
+    let payload: Payload
+    let title: String
+    let subtitle: String?
+    let symbol: String
+    let availability: Availability
+
+    var isEnabled: Bool { availability.isAvailable }
+}
+
+enum WheelKind {
+    case convert
+    case tools
+    case actions
+
+    var title: String {
+        switch self {
+        case .convert: return "Convert"
+        case .tools: return "Tools"
+        case .actions: return "Actions"
+        }
+    }
+}
+
+/// Builds the wheel contents for whatever is being dragged.
+enum WheelBuilder {
+    static func kind(for modifiers: NSEvent.ModifierFlags, settings: Settings = .shared) -> WheelKind? {
+        if modifiers.contains(settings.actionsKey.flag) { return .actions }
+        if modifiers.contains(settings.toolsKey.flag) {
+            if settings.requireShiftForTools, !modifiers.contains(.shift) { return nil }
+            return .tools
+        }
+        if modifiers.contains(settings.convertKey.flag) { return .convert }
+        return nil
+    }
+
+    static func items(kind: WheelKind, urls: [URL], settings: Settings = .shared) -> [WheelItem] {
+        switch kind {
+        case .convert:
+            return conversionItems(urls: urls)
+        case .tools:
+            return toolItems(urls: urls)
+        case .actions:
+            return actionItems(urls: urls, settings: settings)
+        }
+    }
+
+    private static func conversionItems(urls: [URL]) -> [WheelItem] {
+        let categories = urls.map { FileKind.category(of: $0) }
+        let formats = ConversionCatalog.outputs(for: categories)
+        guard let category = categories.first, !formats.isEmpty else { return [] }
+
+        return formats.compactMap { format in
+            guard !ConversionCatalog.isRedundant(format, urls: urls) else { return nil }
+            let availability = Converter.availability(target: format, source: category)
+            return WheelItem(
+                id: "format-\(format.ext)",
+                payload: .format(format),
+                title: format.displayName,
+                subtitle: availability.isAvailable ? nil : availability.reason,
+                symbol: format.symbol,
+                availability: availability
+            )
+        }
+    }
+
+    private static func toolItems(urls: [URL]) -> [WheelItem] {
+        let categories = Set(urls.map { FileKind.category(of: $0) })
+        guard categories.count == 1, let category = categories.first else { return [] }
+
+        return ToolID.tools(for: category).compactMap { tool in
+            guard urls.count >= tool.minimumFileCount else { return nil }
+            var availability = Availability.ok
+            if tool.producesArtifacts, urls.count > 1 {
+                availability = .ok
+            }
+            if requiresFFmpeg(tool), !Toolchain.hasFFmpeg {
+                availability = .unavailable("Needs ffmpeg — brew install ffmpeg")
+            }
+            return WheelItem(
+                id: "tool-\(tool.rawValue)",
+                payload: .tool(tool),
+                title: tool.title,
+                subtitle: availability.isAvailable ? nil : availability.reason,
+                symbol: tool.symbol,
+                availability: availability
+            )
+        }
+    }
+
+    private static func requiresFFmpeg(_ tool: ToolID) -> Bool {
+        switch tool {
+        case .normalizeAudio: return true
+        default: return false
+        }
+    }
+
+    private static func actionItems(urls: [URL], settings: Settings) -> [WheelItem] {
+        let allFolders = urls.allSatisfy { FileKind.category(of: $0) == .folder }
+        return ActionID.allCases.compactMap { action in
+            if allFolders, action != .airdrop, action != .copy, action != .move,
+               action != .copyPath, action != .terminal, action != .revealInFinder {
+                return nil
+            }
+            _ = settings
+            return WheelItem(
+                id: "action-\(action.rawValue)",
+                payload: .action(action),
+                title: action.title,
+                subtitle: nil,
+                symbol: action.symbol,
+                availability: .ok
+            )
+        }
+    }
+
+    /// A one-line description of the selection for the centre of the wheel.
+    static func summary(for urls: [URL]) -> String {
+        guard let first = urls.first else { return "" }
+        if urls.count > 1 { return "\(urls.count) files" }
+        return first.lastPathComponent
+    }
+
+    static func icon(for urls: [URL]) -> NSImage {
+        guard let first = urls.first else {
+            return NSImage(systemSymbolName: "doc", accessibilityDescription: nil) ?? NSImage()
+        }
+        return NSWorkspace.shared.icon(forFile: first.path)
+    }
+}
diff --git a/Sources/Konverter/Drag/DragMonitor.swift b/Sources/Konverter/Drag/DragMonitor.swift
new file mode 100644
index 0000000..e21043d
--- /dev/null
+++ b/Sources/Konverter/Drag/DragMonitor.swift
@@ -0,0 +1,127 @@
+import AppKit
+import Foundation
+
+/// Watches for drags anywhere on the system and reports them. Mouse events do
+/// not require any privacy permission; key events (Escape, arrows) do, so the
+/// wheel stays fully usable without them.
+final class DragMonitor {
+    static let shared = DragMonitor()
+
+    /// Called on every poll while a drag is in flight.
+    var onTick: (([URL], CGPoint, NSEvent.ModifierFlags) -> Void)?
+    /// Called once when a drag starts, with the files being dragged.
+    var onBegan: (([URL]) -> Void)?
+    /// Called when the drag finishes (drop or cancel).
+    var onEnded: ((CGPoint) -> Void)?
+    /// Called for keys pressed during a drag.
+    var onKey: ((UInt16, NSEvent.ModifierFlags) -> Bool)?
+
+    private var globalMouse: Any?
+    private var localMouse: Any?
+    private var keyMonitor: Any?
+    private var timer: Timer?
+    private var isDragging = false
+    private var urls: [URL] = []
+
+    private init() {}
+
+    func start() {
+        guard globalMouse == nil else { return }
+
+        let mask: NSEvent.EventTypeMask = [.leftMouseDragged, .rightMouseDragged, .otherMouseDragged]
+        globalMouse = NSEvent.addGlobalMonitorForEvents(matching: mask) { [weak self] event in
+            self?.handleDrag(event)
+        }
+        // Drags that end up over our own window are delivered to us, so the
+        // global monitor never sees them.
+        localMouse = NSEvent.addLocalMonitorForEvents(matching: mask) { [weak self] event in
+            self?.handleDrag(event)
+            return event
+        }
+
+        let upMask: NSEvent.EventTypeMask = [.leftMouseUp, .rightMouseUp, .otherMouseUp]
+        NSEvent.addGlobalMonitorForEvents(matching: upMask) { [weak self] _ in
+            self?.handleEnd()
+        }
+        NSEvent.addLocalMonitorForEvents(matching: upMask) { [weak self] event in
+            self?.handleEnd()
+            return event
+        }
+
+        keyMonitor = NSEvent.addGlobalMonitorForEvents(matching: .keyDown) { [weak self] event in
+            guard let self, self.isDragging else { return }
+            _ = self.onKey?(event.keyCode, event.modifierFlags)
+        }
+    }
+
+    func stop() {
+        if let globalMouse { NSEvent.removeMonitor(globalMouse) }
+        if let localMouse { NSEvent.removeMonitor(localMouse) }
+        if let keyMonitor { NSEvent.removeMonitor(keyMonitor) }
+        globalMouse = nil
+        localMouse = nil
+        keyMonitor = nil
+        stopTimer()
+    }
+
+    private func handleDrag(_ event: NSEvent) {
+        if !isDragging {
+            let dragged = DragMonitor.draggedFileURLs()
+            guard !dragged.isEmpty else { return }
+            isDragging = true
+            urls = dragged
+            onBegan?(dragged)
+            startTimer()
+        }
+    }
+
+    private func handleEnd() {
+        guard isDragging else { return }
+        onEnded?(NSEvent.mouseLocation)
+        isDragging = false
+        urls = []
+        stopTimer()
+    }
+
+    private func startTimer() {
+        stopTimer()
+        let timer = Timer(timeInterval: 1.0 / 60.0, repeats: true) { [weak self] _ in
+            guard let self, self.isDragging else { return }
+            self.onTick?(self.urls, NSEvent.mouseLocation, NSEvent.modifierFlags)
+        }
+        // `.common` keeps it firing even if a tracking loop is running.
+        RunLoop.main.add(timer, forMode: .common)
+        self.timer = timer
+    }
+
+    private func stopTimer() {
+        timer?.invalidate()
+        timer = nil
+    }
+
+    /// The files currently on the global drag pasteboard. Finder, Mail and most
+    /// apps publish real file URLs; apps that only promise a file are read too.
+    static func draggedFileURLs() -> [URL] {
+        let pasteboard = NSPasteboard(name: .drag)
+        guard let types = pasteboard.types else { return [] }
+
+        let fileTypes: Set<NSPasteboard.PasteboardType> = [
+            .fileURL,
+            .filePromise,
+            NSPasteboard.PasteboardType("NSFilenamesPboardType")
+        ]
+        guard types.contains(where: { fileTypes.contains($0) }) else { return [] }
+
+        var urls: [URL] = []
+        if let objects = pasteboard.readObjects(
+            forClasses: [NSURL.self],
+            options: [.urlReadingFileURLsOnly: true]
+        ) as? [URL] {
+            urls = objects
+        }
+        if urls.isEmpty, let paths = pasteboard.propertyList(forType: NSPasteboard.PasteboardType("NSFilenamesPboardType")) as? [String] {
+            urls = paths.map { URL(fileURLWithPath: $0) }
+        }
+        return urls.filter { FileManager.default.fileExists(atPath: $0.path) }
+    }
+}
diff --git a/Sources/Konverter/Drag/WheelController.swift b/Sources/Konverter/Drag/WheelController.swift
new file mode 100644
index 0000000..aa78a24
--- /dev/null
+++ b/Sources/Konverter/Drag/WheelController.swift
@@ -0,0 +1,354 @@
+import AppKit
+import Combine
+import Foundation
+import SwiftUI
+
+/// State behind the wheel: what is offered, what is highlighted, and what the
+/// centre of the wheel says.
+final class WheelModel: ObservableObject {
+    @Published var kind: WheelKind = .convert
+    @Published var items: [WheelItem] = []
+    @Published var selection: Int?
+    @Published var summary: String = ""
+    @Published var subtitle: String = ""
+    @Published var icon: NSImage = NSImage()
+    @Published var radius: CGFloat = 168
+
+    var selectedItem: WheelItem? {
+        guard let selection, items.indices.contains(selection) else { return nil }
+        return items[selection]
+    }
+}
+
+/// Accepts the drop. Being a real drag destination is what stops Finder from
+/// moving the file, and it is how the wheel learns about the drop without
+/// needing an Accessibility event tap.
+final class DropCatcher: NSView {
+    var onMoved: ((CGPoint) -> Void)?
+    var onExit: (() -> Void)?
+    var onDrop: (() -> Bool)?
+
+    override init(frame frameRect: NSRect) {
+        super.init(frame: frameRect)
+        registerForDraggedTypes([.fileURL, .filePromise, NSPasteboard.PasteboardType("NSFilenamesPboardType")])
+    }
+
+    required init?(coder: NSCoder) { nil }
+
+    private func screenPoint(_ sender: NSDraggingInfo) -> CGPoint {
+        guard let window else { return NSEvent.mouseLocation }
+        let inWindow = sender.draggingLocation
+        return window.convertPoint(toScreen: inWindow)
+    }
+
+    override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
+        onMoved?(screenPoint(sender))
+        return .generic
+    }
+
+    override func draggingUpdated(_ sender: NSDraggingInfo) -> NSDragOperation {
+        onMoved?(screenPoint(sender))
+        return .generic
+    }
+
+    override func draggingExited(_ sender: NSDraggingInfo?) {
+        onExit?()
+    }
+
+    override func prepareForDragOperation(_ sender: NSDraggingInfo) -> Bool { true }
+
+    override func performDragOperation(_ sender: NSDraggingInfo) -> Bool {
+        onMoved?(screenPoint(sender))
+        return onDrop?() ?? false
+    }
+}
+
+/// Owns the overlay window and turns drags into jobs.
+final class WheelController {
+    static let shared = WheelController()
+
+    private let model = WheelModel()
+    private var window: NSWindow?
+    private var catcher: DropCatcher?
+    private var urls: [URL] = []
+    private var isShowing = false
+    private var didHandleDrop = false
+    private var lastLocation: CGPoint = .zero
+    private var pendingDismiss: DispatchWorkItem?
+
+    private init() {}
+
+    // MARK: - Drag lifecycle
+
+    func begin(urls: [URL]) {
+        self.urls = urls
+        didHandleDrop = false
+    }
+
+    func tick(location: CGPoint, modifiers: NSEvent.ModifierFlags) {
+        guard !urls.isEmpty else { return }
+        guard let kind = WheelBuilder.kind(for: modifiers) else {
+            // No trigger key held: stay out of the way until one is pressed.
+            if !isShowing { model.selection = nil }
+            return
+        }
+        let items = WheelBuilder.items(kind: kind, urls: urls)
+        guard !items.isEmpty else {
+            dismiss()
+            return
+        }
+        if !isShowing || model.kind != kind || model.items.map(\.id) != items.map(\.id) {
+            present(kind: kind, items: items, at: location)
+        } else {
+            move(to: location)
+        }
+    }
+
+    /// Drop committed by the drag destination.
+    @discardableResult
+    func commitDrop() -> Bool {
+        guard let item = model.selectedItem else {
+            dismiss()
+            return false
+        }
+        guard item.isEnabled else {
+            let reason = item.availability.reason ?? "Unavailable"
+            DispatchQueue.main.async {
+                Notifier.error(item.title, reason)
+            }
+            dismiss()
+            return true
+        }
+        didHandleDrop = true
+        let captured = urls
+        let origin = lastLocation
+        dismiss(animated: false)
+        WheelController.dispatch(item: item, urls: captured, origin: origin)
+        return true
+    }
+
+    func end() {
+        guard isShowing else { return }
+        // Give the drag destination a beat to deliver the drop first.
+        let work = DispatchWorkItem { [weak self] in
+            guard let self else { return }
+            if self.didHandleDrop { return }
+            if let item = self.model.selectedItem, item.isEnabled {
+                let captured = self.urls
+                let origin = self.lastLocation
+                self.dismiss(animated: false)
+                WheelController.dispatch(item: item, urls: captured, origin: origin)
+            } else {
+                self.dismiss()
+            }
+        }
+        pendingDismiss = work
+        DispatchQueue.main.asyncAfter(deadline: .now() + 0.22, execute: work)
+    }
+
+    func cancel() {
+        pendingDismiss?.cancel()
+        dismiss()
+    }
+
+    func handleKey(_ keyCode: UInt16, modifiers: NSEvent.ModifierFlags) -> Bool {
+        guard isShowing else { return false }
+        switch keyCode {
+        case 53: // Escape
+            cancel()
+            return true
+        case 123, 126: // Left / Up
+            step(-1)
+            return true
+        case 124, 125: // Right / Down
+            step(1)
+            return true
+        case 36, 76: // Return / Enter
+            commitDrop()
+            return true
+        default:
+            return false
+        }
+    }
+
+    private func step(_ delta: Int) {
+        guard !model.items.isEmpty else { return }
+        let count = model.items.count
+        let current = model.selection ?? 0
+        model.selection = ((current + delta) % count + count) % count
+    }
+
+    // MARK: - Window
+
+    private func present(kind: WheelKind, items: [WheelItem], at location: CGPoint) {
+        pendingDismiss?.cancel()
+
+        let radius = Self.radius(forItemCount: items.count)
+        let itemExtent: CGFloat = 86
+        let size = (radius + itemExtent) * 2
+
+        model.kind = kind
+        model.items = items
+        model.radius = radius
+        model.summary = WheelBuilder.summary(for: urls)
+        model.subtitle = kind.title
+        model.icon = WheelBuilder.icon(for: urls)
+
+        let frame = CGRect(
+            x: location.x - size / 2,
+            y: location.y - size / 2,
+            width: size,
+            height: size
+        )
+
+        let window: NSWindow
+        if let existing = self.window {
+            window = existing
+        } else {
+            let created = OverlayWindow(
+                contentRect: frame,
+                styleMask: [.borderless],
+                backing: .buffered,
+                defer: false
+            )
+            created.isOpaque = false
+            created.backgroundColor = .clear
+            created.hasShadow = false
+            created.level = NSWindow.Level(rawValue: Int(CGWindowLevelForKey(.screenSaverWindow)) - 1)
+            created.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .stationary, .ignoresCycle]
+            created.ignoresMouseEvents = false
+            created.isMovable = false
+            created.animationBehavior = .none
+
+            let catcher = DropCatcher(frame: CGRect(origin: .zero, size: CGSize(width: size, height: size)))
+            catcher.autoresizingMask = [.width, .height]
+            catcher.wantsLayer = true
+            let hosting = NSHostingView(rootView: WheelView(model: model))
+            hosting.frame = catcher.bounds
+            hosting.autoresizingMask = [.width, .height]
+            catcher.addSubview(hosting)
+
+            catcher.onMoved = { [weak self] point in
+                self?.move(to: point)
+            }
+            catcher.onExit = { [weak self] in
+                self?.model.selection = nil
+            }
+            catcher.onDrop = { [weak self] in
+                self?.commitDrop() ?? false
+            }
+
+            created.contentView = catcher
+            self.catcher = catcher
+            self.window = created
+            window = created
+        }
+
+        if !isShowing {
+            window.alphaValue = 0
+            window.orderFrontRegardless()
+            NSAnimationContext.runAnimationGroup { context in
+                context.duration = 0.12
+                window.animator().alphaValue = 1
+            }
+        } else {
+            window.setFrame(frame, display: true)
+        }
+        isShowing = true
+        move(to: location)
+    }
+
+    private func move(to location: CGPoint) {
+        guard let window else { return }
+        lastLocation = location
+        var frame = window.frame
+        frame.origin = CGPoint(x: location.x - frame.width / 2, y: location.y - frame.height / 2)
+        window.setFrame(frame, display: true)
+        model.selection = Self.selectionIndex(for: location, in: frame, items: model.items, radius: model.radius)
+    }
+
+    private func dismiss(animated: Bool = true) {
+        pendingDismiss?.cancel()
+        guard let window, isShowing else {
+            isShowing = false
+            return
+        }
+        isShowing = false
+        model.selection = nil
+        if animated {
+            NSAnimationContext.runAnimationGroup { context in
+                context.duration = 0.1
+                window.animator().alphaValue = 0
+            } completionHandler: {
+                window.orderOut(nil)
+            }
+        } else {
+            window.orderOut(nil)
+        }
+    }
+
+    func reset() {
+        urls = []
+        dismiss(animated: false)
+    }
+
+    // MARK: - Geometry
+
+    /// Items are spread on a ring; the radius grows with the item count so the
+    /// pills never touch.
+    static func radius(forItemCount count: Int) -> CGFloat {
+        let base = Settings.shared.wheelRadius
+        guard count > 2 else { return base }
+        let arc = CGFloat(count) * 84 / (2 * .pi)
+        return max(base, arc + 40)
+    }
+
+    /// Nearest item to the pointer, or nil when the pointer is off the ring or
+    /// in the dead zone at the centre.
+    static func selectionIndex(for location: CGPoint, in frame: CGRect, items: [WheelItem], radius: CGFloat) -> Int? {
+        guard !items.isEmpty else { return nil }
+        let center = CGPoint(x: frame.midX, y: frame.midY)
+        let dx = location.x - center.x
+        let dy = location.y - center.y
+        let distance = (dx * dx + dy * dy).squareRoot()
+
+        guard distance > radius * 0.34 else { return nil }
+        if items.count == 1 { return 0 }
+        guard distance < radius * 1.75 else { return nil }
+
+        var angle = atan2(dy, dx) * 180 / .pi
+        if angle < 0 { angle += 360 }
+        let step = 360 / Double(items.count)
+        let firstItemAngle = 90.0
+        var offset = (firstItemAngle - angle).truncatingRemainder(dividingBy: 360)
+        if offset < 0 { offset += 360 }
+        let index = Int((offset / step).rounded()) % items.count
+        return index
+    }
+
+    // MARK: - Dispatch
+
+    private static func dispatch(item: WheelItem, urls: [URL], origin: CGPoint?) {
+        switch item.payload {
+        case .format(let format):
+            JobStore.shared.submit(urls: urls, target: .format(format), origin: origin)
+
+        case .tool(let tool):
+            if tool.fields.isEmpty {
+                JobStore.shared.submit(urls: urls, target: .tool(tool), origin: origin)
+            } else {
+                OptionsWindowController.shared.present(tool: tool, urls: urls, origin: origin)
+            }
+
+        case .action(let action):
+            JobStore.shared.submit(urls: urls, target: .action(action), origin: origin)
+        }
+    }
+}
+
+/// A window that never steals focus and never becomes the key window, so the
+/// user's drag and the frontmost app keep working.
+final class OverlayWindow: NSWindow {
+    override var canBecomeKey: Bool { false }
+    override var canBecomeMain: Bool { false }
+}
diff --git a/Sources/Konverter/Drag/WheelView.swift b/Sources/Konverter/Drag/WheelView.swift
new file mode 100644
index 0000000..ff24b96
--- /dev/null
+++ b/Sources/Konverter/Drag/WheelView.swift
@@ -0,0 +1,170 @@
+import AppKit
+import SwiftUI
+
+/// The wheel itself: a ring of output formats with the dragged file in the
+/// middle. Rendered into a transparent, non-activating overlay window.
+struct WheelView: View {
+    @ObservedObject var model: WheelModel
+
+    var body: some View {
+        GeometryReader { proxy in
+            let size = proxy.size
+            let center = CGPoint(x: size.width / 2, y: size.height / 2)
+
+            ZStack {
+                if Settings.shared.dimBackground {
+                    Circle()
+                        .fill(Color.black.opacity(0.22))
+                        .frame(width: model.radius * 3.4, height: model.radius * 3.4)
+                        .position(center)
+                        .blur(radius: 24)
+                }
+
+                disc(center: center)
+
+                centerBadge(center: center)
+
+                ForEach(Array(model.items.enumerated()), id: \.element.id) { index, item in
+                    itemView(item, isSelected: model.selection == index)
+                        .position(position(for: index, count: model.items.count, center: center))
+                }
+            }
+        }
+        .frame(maxWidth: .infinity, maxHeight: .infinity)
+    }
+
+    // MARK: - Pieces
+
+    private func disc(center: CGPoint) -> some View {
+        let diameter = (model.radius + 46) * 2
+        return ZStack {
+            Circle()
+                .fill(.ultraThinMaterial)
+            Circle()
+                .strokeBorder(Color.white.opacity(0.14), lineWidth: 1)
+            Circle()
+                .strokeBorder(Color.white.opacity(0.06), lineWidth: 1)
+                .frame(width: diameter - 26, height: diameter - 26)
+        }
+        .frame(width: diameter, height: diameter)
+        .position(center)
+        .shadow(color: .black.opacity(0.28), radius: 22, y: 6)
+    }
+
+    private func centerBadge(center: CGPoint) -> some View {
+        VStack(spacing: 5) {
+            Image(nsImage: model.icon)
+                .resizable()
+                .aspectRatio(contentMode: .fit)
+                .frame(width: 40, height: 40)
+            Text(model.summary)
+                .font(.system(size: 11, weight: .medium))
+                .lineLimit(1)
+                .truncationMode(.middle)
+                .frame(maxWidth: max(90, model.radius * 0.95))
+            if let item = model.selectedItem, !item.isEnabled, let reason = item.availability.reason {
+                Text(reason)
+                    .font(.system(size: 9))
+                    .foregroundStyle(.orange)
+                    .multilineTextAlignment(.center)
+                    .lineLimit(2)
+                    .frame(maxWidth: max(110, model.radius * 1.1))
+            } else {
+                Text(model.subtitle)
+                    .font(.system(size: 9, weight: .semibold))
+                    .foregroundStyle(.secondary)
+                    .textCase(.uppercase)
+            }
+        }
+        .padding(10)
+        .background(
+            Circle()
+                .fill(Color(nsColor: .windowBackgroundColor).opacity(0.55))
+        )
+        .position(center)
+    }
+
+    private func itemView(_ item: WheelItem, isSelected: Bool) -> some View {
+        VStack(spacing: 4) {
+            ZStack {
+                Circle()
+                    .fill(isSelected ? Color.accentColor.opacity(0.92) : Color.black.opacity(0.34))
+                Circle()
+                    .strokeBorder(Color.white.opacity(isSelected ? 0.85 : 0.16), lineWidth: isSelected ? 1.5 : 1)
+                Image(systemName: item.symbol)
+                    .font(.system(size: 19, weight: .semibold))
+                    .foregroundStyle(.white)
+                if !item.isEnabled {
+                    Image(systemName: "lock.fill")
+                        .font(.system(size: 9, weight: .bold))
+                        .foregroundStyle(.white)
+                        .padding(3)
+                        .background(Circle().fill(Color.orange))
+                        .offset(x: 16, y: -16)
+                }
+            }
+            .frame(width: 46, height: 46)
+
+            if Settings.shared.showLabels {
+                Text(item.title)
+                    .font(.system(size: 10.5, weight: .semibold))
+                    .foregroundStyle(.white)
+                    .lineLimit(1)
+                    .minimumScaleFactor(0.75)
+                    .shadow(color: .black.opacity(0.65), radius: 2, y: 1)
+            }
+        }
+        .frame(width: 84)
+        .opacity(item.isEnabled ? 1 : 0.62)
+        .scaleEffect(isSelected ? 1.14 : 1)
+        .animation(.spring(response: 0.18, dampingFraction: 0.8), value: isSelected)
+    }
+
+    private func position(for index: Int, count: Int, center: CGPoint) -> CGPoint {
+        guard count > 0 else { return center }
+        let step = 360.0 / Double(count)
+        let degrees = 90.0 - Double(index) * step
+        let radians = degrees * .pi / 180
+        return CGPoint(
+            x: center.x + CGFloat(cos(radians)) * model.radius,
+            y: center.y - CGFloat(sin(radians)) * model.radius
+        )
+    }
+}
+
+/// Compact list rendering, for users who prefer a straight menu.
+struct WheelListView: View {
+    @ObservedObject var model: WheelModel
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 2) {
+            Text(model.summary)
+                .font(.system(size: 11, weight: .semibold))
+                .foregroundStyle(.secondary)
+                .lineLimit(1)
+            ForEach(Array(model.items.enumerated()), id: \.element.id) { index, item in
+                HStack(spacing: 8) {
+                    Image(systemName: item.symbol)
+                        .font(.system(size: 11))
+                        .frame(width: 16)
+                    Text(item.title)
+                        .font(.system(size: 12))
+                    Spacer(minLength: 8)
+                    if !item.isEnabled {
+                        Image(systemName: "lock.fill").font(.system(size: 9))
+                    }
+                }
+                .padding(.horizontal, 8)
+                .padding(.vertical, 4)
+                .background(
+                    RoundedRectangle(cornerRadius: 6)
+                        .fill(model.selection == index ? Color.accentColor.opacity(0.85) : Color.clear)
+                )
+                .foregroundStyle(model.selection == index ? Color.white : Color.primary)
+            }
+        }
+        .padding(10)
+        .frame(width: 220)
+        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 12))
+    }
+}
diff --git a/Sources/Konverter/SelfTest.swift b/Sources/Konverter/SelfTest.swift
new file mode 100644
index 0000000..d3020cb
--- /dev/null
+++ b/Sources/Konverter/SelfTest.swift
@@ -0,0 +1,475 @@
+import AppKit
+import CoreGraphics
+import Foundation
+
+/// `--self-test` exercises the real conversion paths end to end and exits
+/// non-zero on failure. Kept in the shipped binary so a build can be verified
+/// without opening the UI.
+enum SelfTest {
+    private static var passes = 0
+    private static var failures = 0
+    private static var directory = FileManager.default.temporaryDirectory
+
+    static func run() -> Int32 {
+        directory = FileManager.default.temporaryDirectory
+            .appendingPathComponent("konverter-selftest-\(UUID().uuidString)", isDirectory: true)
+        try? FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(at: directory) }
+
+        print("Konverter self-test")
+        print("Working in \(directory.path)")
+        print("Engines: \(Toolchain.summary)")
+        print("")
+
+        testImages()
+        testPDF()
+        testSubtitles()
+        testSpreadsheets()
+        testArchives()
+        testDocuments()
+        testAudio()
+        testEbook()
+        testGeometry()
+
+        print("")
+        print("\(passes) passed, \(failures) failed")
+        return failures == 0 ? 0 : 1
+    }
+
+    // MARK: - Suites
+
+    private static func testImages() {
+        section("Images")
+        let source = directory.appendingPathComponent("sample.png")
+        check("create sample png") {
+            try makeImage(at: source, width: 320, height: 200)
+            try requireFile(source)
+        }
+
+        for format in [Format.jpg, .tiff, .gif, .pdf, .webp, .heic, .avif] {
+            let availability = Converter.availability(target: format, source: .image)
+            guard availability.isAvailable else {
+                print("SKIP  png → \(format.displayName) (\(availability.reason ?? "unavailable"))")
+                continue
+            }
+            check("png → \(format.displayName)") {
+                let output = directory.appendingPathComponent("out.\(format.ext)")
+                try ImageConverter.convert(source: source, to: format, at: output)
+                try requireFile(output)
+            }
+        }
+
+        check("image compress") {
+            let output = directory.appendingPathComponent("compressed.jpg")
+            try ImageTools.compress(source, at: output, format: .jpg, quality: 0.4)
+            try requireFile(output)
+        }
+
+        // PNG has no quality knob, so "compress" trades colour depth for size.
+        check("png compress shrinks a lossless file") {
+            let output = directory.appendingPathComponent("compressed.png")
+            try ImageTools.compress(source, at: output, format: .png, quality: 0.3)
+            try requireFile(output)
+            let before = try fileSize(source)
+            let after = try fileSize(output)
+            guard after < before else {
+                throw TestFailure("expected a smaller png, got \(before) → \(after) bytes")
+            }
+        }
+
+        check("image resize") {
+            let output = directory.appendingPathComponent("resized.png")
+            try ImageTools.resize(source, at: output, maxWidth: 100, maxHeight: 100, percent: 100)
+            guard let image = Raster.firstImage(at: output), image.width <= 100 else {
+                throw TestFailure("resize did not shrink the image")
+            }
+        }
+
+        check("image rotate") {
+            let output = directory.appendingPathComponent("rotated.png")
+            try ImageTools.rotate(source, at: output, degrees: 90)
+            guard let image = Raster.firstImage(at: output), image.height > image.width else {
+                throw TestFailure("rotation did not swap dimensions")
+            }
+        }
+    }
+
+    private static func testPDF() {
+        section("PDF")
+        let image = directory.appendingPathComponent("sample.png")
+        let pdf = directory.appendingPathComponent("sample.pdf")
+
+        check("image → pdf") {
+            try PDFConverter.imageToPDF(image, at: pdf)
+            try requireFile(pdf)
+        }
+
+        check("pdf text extraction") {
+            let textPDF = directory.appendingPathComponent("text.pdf")
+            try TextDocument.writePDF(fromText: "Hello Konverter", to: textPDF)
+            let text = PDFConverter.extractText(textPDF)
+            guard text.contains("Hello") else { throw TestFailure("no text found in \(text)") }
+        }
+
+        check("pdf → png pages") {
+            let folder = directory.appendingPathComponent("pages")
+            let written = try PDFConverter.renderPages(pdf, to: .png, into: folder, dpi: 72)
+            guard !written.isEmpty else { throw TestFailure("no pages rendered") }
+            try requireFile(written[0])
+        }
+
+        check("pdf split and merge") {
+            let split = try PDFConverter.split(pdf, pagesPerFile: 1, into: directory.appendingPathComponent("split"))
+            guard split.count == 1 else { throw TestFailure("expected one part, got \(split.count)") }
+            let merged = directory.appendingPathComponent("merged.pdf")
+            try PDFConverter.merge(split, at: merged)
+            guard PDFConverter.pageCount(merged) == 1 else { throw TestFailure("merge lost pages") }
+        }
+    }
+
+    private static func testSubtitles() {
+        section("Subtitles")
+        let srt = directory.appendingPathComponent("captions.srt")
+        try? """
+        1
+        00:00:01,000 --> 00:00:03,500
+        First line
+
+        2
+        00:00:04,000 --> 00:00:06,000
+        Second line
+
+        """.write(to: srt, atomically: true, encoding: .utf8)
+
+        check("srt → vtt") {
+            let vtt = directory.appendingPathComponent("captions.vtt")
+            try SubtitleConverter.convert(source: srt, to: .vtt, at: vtt)
+            let text = try String(contentsOf: vtt, encoding: .utf8)
+            guard text.hasPrefix("WEBVTT"), text.contains("00:00:01.000") else {
+                throw TestFailure("unexpected vtt output")
+            }
+        }
+
+        check("srt → txt") {
+            let text = directory.appendingPathComponent("captions.txt")
+            try SubtitleConverter.convert(source: srt, to: .txt, at: text)
+            let contents = try String(contentsOf: text, encoding: .utf8)
+            guard contents.contains("First line") else { throw TestFailure("missing cue text") }
+        }
+
+        check("subtitle offset") {
+            let cues = try SubtitleConverter.parse(srt)
+            let shifted = SubtitleConverter.shift(cues, by: 2)
+            guard let first = shifted.first, abs(first.start - 3) < 0.01 else {
+                throw TestFailure("offset was not applied")
+            }
+        }
+    }
+
+    private static func testSpreadsheets() {
+        section("Spreadsheets")
+        let csv = directory.appendingPathComponent("table.csv")
+        try? "Name,Score\nAda,42\nGrace,\"7,5\"\n".write(to: csv, atomically: true, encoding: .utf8)
+
+        check("csv parse") {
+            let rows = try SpreadsheetConverter.read(csv)
+            guard rows.count == 3, rows[1][0] == "Ada", rows[2][1] == "7,5" else {
+                throw TestFailure("parsed \(rows)")
+            }
+        }
+
+        check("csv → xlsx → csv") {
+            let xlsx = directory.appendingPathComponent("table.xlsx")
+            let rows = try SpreadsheetConverter.read(csv)
+            try XLSX.write(rows, to: xlsx)
+            try requireFile(xlsx)
+            let roundTrip = try XLSX.read(xlsx)
+            guard roundTrip.count == rows.count, roundTrip[1][0] == "Ada" else {
+                throw TestFailure("round trip produced \(roundTrip)")
+            }
+        }
+
+        check("csv → tsv") {
+            let tsv = directory.appendingPathComponent("table.tsv")
+            try SpreadsheetConverter.convert(source: csv, to: .tsv, at: tsv)
+            let text = try String(contentsOf: tsv, encoding: .utf8)
+            guard text.contains("\t") else { throw TestFailure("no tabs in output") }
+        }
+    }
+
+    private static func testArchives() {
+        section("Archives")
+        let folder = directory.appendingPathComponent("bundle", isDirectory: true)
+        try? FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
+        try? "archive me".write(to: folder.appendingPathComponent("note.txt"), atomically: true, encoding: .utf8)
+
+        check("folder → zip") {
+            let zip = directory.appendingPathComponent("bundle.zip")
+            try ArchiveConverter.convert(source: folder, to: .zip, at: zip)
+            try requireFile(zip)
+        }
+
+        check("zip → extract") {
+            let zip = directory.appendingPathComponent("bundle.zip")
+            let target = directory.appendingPathComponent("unpacked", isDirectory: true)
+            try ArchiveConverter.extract(source: zip, into: target)
+            let note = target.appendingPathComponent("bundle/note.txt")
+            guard FileManager.default.fileExists(atPath: note.path) else {
+                throw TestFailure("note.txt missing after extraction")
+            }
+        }
+
+        check("folder → tar") {
+            let tar = directory.appendingPathComponent("bundle.tar")
+            try ArchiveConverter.convert(source: folder, to: .tar, at: tar)
+            try requireFile(tar)
+        }
+    }
+
+    private static func testDocuments() {
+        section("Documents")
+        let text = directory.appendingPathComponent("note.txt")
+        try? "Hello from Konverter.\n\nSecond paragraph.\n".write(to: text, atomically: true, encoding: .utf8)
+
+        check("txt → md") {
+            let markdown = directory.appendingPathComponent("note.md")
+            try DocumentConverter.convert(source: text, to: .md, at: markdown)
+            let contents = try String(contentsOf: markdown, encoding: .utf8)
+            guard contents.contains("Hello from Konverter") else { throw TestFailure("text lost") }
+        }
+
+        check("md → html") {
+            let markdown = directory.appendingPathComponent("note.md")
+            try? "# Title\n\nSome **bold** text.\n".write(to: markdown, atomically: true, encoding: .utf8)
+            let html = directory.appendingPathComponent("note.html")
+            try DocumentConverter.convert(source: markdown, to: .html, at: html)
+            let contents = try String(contentsOf: html, encoding: .utf8)
+            guard contents.contains("<strong>bold</strong>") else { throw TestFailure("markdown not rendered") }
+        }
+
+        check("txt → pdf") {
+            let pdf = directory.appendingPathComponent("note.pdf")
+            try DocumentConverter.convert(source: text, to: .pdf, at: pdf)
+            try requireFile(pdf)
+            guard PDFConverter.pageCount(pdf) >= 1 else { throw TestFailure("empty pdf") }
+        }
+
+        check("txt → docx") {
+            let docx = directory.appendingPathComponent("note.docx")
+            try DocumentConverter.convert(source: text, to: .docx, at: docx)
+            try requireFile(docx)
+        }
+
+        check("html → md") {
+            let markdown = Markdown.markdown(fromHTML: "<h1>Title</h1><p>Hello <strong>world</strong></p>")
+            guard markdown.contains("# Title"), markdown.contains("**world**") else {
+                throw TestFailure("html not converted: \(markdown)")
+            }
+        }
+    }
+
+    private static func testAudio() {
+        section("Audio")
+        let wav = directory.appendingPathComponent("tone.wav")
+
+        check("create wav") {
+            try makeWAV(at: wav)
+            try requireFile(wav)
+        }
+
+        check("wav → m4a") {
+            let m4a = directory.appendingPathComponent("tone.m4a")
+            try AVConverter.convert(source: wav, to: .m4a, at: m4a)
+            try requireFile(m4a)
+        }
+
+        check("wav → aiff") {
+            let aiff = directory.appendingPathComponent("tone.aiff")
+            try CoreAudio.convert(source: wav, to: .aiff, at: aiff)
+            try requireFile(aiff)
+        }
+
+        check("media info") {
+            let info = MediaInfo.describe(wav)
+            guard info.contains("Duration") else { throw TestFailure("no duration in \(info)") }
+        }
+    }
+
+    private static func testEbook() {
+        section("EPUB")
+        let html = "<h1>Chapter</h1><p>An ebook built from scratch.</p>"
+        let epub = directory.appendingPathComponent("book.epub")
+
+        check("build epub") {
+            try EbookConverter.write(
+                title: "Test Book",
+                author: "Konverter",
+                chapters: [("One", html), ("Two", "<p>More text.</p>")],
+                at: epub
+            )
+            try requireFile(epub)
+        }
+
+        check("epub → txt") {
+            let text = try EbookConverter.plainText(epub)
+            guard text.contains("ebook built from scratch") else {
+                throw TestFailure("chapter text missing: \(text)")
+            }
+        }
+
+        check("epub → md") {
+            let markdown = directory.appendingPathComponent("book.md")
+            try EbookConverter.convert(source: epub, to: .md, at: markdown)
+            let contents = try String(contentsOf: markdown, encoding: .utf8)
+            guard contents.contains("ebook built") else { throw TestFailure("markdown lost the text") }
+        }
+    }
+
+    private static func testGeometry() {
+        section("Wheel geometry")
+        let frame = CGRect(x: 0, y: 0, width: 400, height: 400)
+        let items = (0..<8).map { index in
+            WheelItem(
+                id: "item-\(index)",
+                payload: .format(.png),
+                title: "Item \(index)",
+                subtitle: nil,
+                symbol: "circle",
+                availability: .ok
+            )
+        }
+        let radius: CGFloat = 160
+
+        check("top hit selects the first item") {
+            let index = WheelController.selectionIndex(
+                for: CGPoint(x: 200, y: 340),
+                in: frame,
+                items: items,
+                radius: radius
+            )
+            guard index == 0 else { throw TestFailure("got \(String(describing: index))") }
+        }
+
+        check("dead zone selects nothing") {
+            let index = WheelController.selectionIndex(
+                for: CGPoint(x: 200, y: 200),
+                in: frame,
+                items: items,
+                radius: radius
+            )
+            guard index == nil else { throw TestFailure("got \(String(describing: index))") }
+        }
+
+        check("clockwise hit selects item 2") {
+            let index = WheelController.selectionIndex(
+                for: CGPoint(x: 360, y: 200),
+                in: frame,
+                items: items,
+                radius: radius
+            )
+            guard index == 2 else { throw TestFailure("got \(String(describing: index))") }
+        }
+
+        check("conflict naming") {
+            let existing = directory.appendingPathComponent("taken.txt")
+            try? "x".write(to: existing, atomically: true, encoding: .utf8)
+            let candidate = OutputNaming.availableURL(for: existing)
+            guard candidate.lastPathComponent == "taken 2.txt" else {
+                throw TestFailure("got \(candidate.lastPathComponent)")
+            }
+        }
+    }
+
+    // MARK: - Harness
+
+    private struct TestFailure: LocalizedError {
+        let message: String
+        init(_ message: String) { self.message = message }
+        var errorDescription: String? { message }
+    }
+
+    private static func section(_ name: String) {
+        print("— \(name)")
+    }
+
+    private static func check(_ name: String, _ body: () throws -> Void) {
+        do {
+            try body()
+            passes += 1
+            print("PASS  \(name)")
+        } catch {
+            failures += 1
+            let message = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
+            print("FAIL  \(name): \(message)")
+        }
+    }
+
+    private static func requireFile(_ url: URL) throws {
+        guard FileManager.default.fileExists(atPath: url.path) else {
+            throw TestFailure("\(url.lastPathComponent) was not created")
+        }
+        let size = try fileSize(url)
+        guard size > 0 else {
+            throw TestFailure("\(url.lastPathComponent) is empty")
+        }
+    }
+
+    private static func fileSize(_ url: URL) throws -> Int {
+        let attributes = try FileManager.default.attributesOfItem(atPath: url.path)
+        return attributes[.size] as? Int ?? 0
+    }
+
+    private static func makeImage(at url: URL, width: Int, height: Int) throws {
+        guard let context = CGContext(
+            data: nil,
+            width: width,
+            height: height,
+            bitsPerComponent: 8,
+            bytesPerRow: 0,
+            space: CGColorSpace(name: CGColorSpace.sRGB) ?? CGColorSpaceCreateDeviceRGB(),
+            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
+        ) else { throw TestFailure("could not create a bitmap") }
+
+        context.setFillColor(CGColor(srgbRed: 0.98, green: 0.52, blue: 0.18, alpha: 1))
+        context.fill(CGRect(x: 0, y: 0, width: width, height: height))
+        context.setFillColor(CGColor(srgbRed: 1, green: 1, blue: 1, alpha: 1))
+        context.fillEllipse(in: CGRect(x: width / 4, y: height / 4, width: width / 2, height: height / 2))
+
+        guard let image = context.makeImage() else { throw TestFailure("could not render the bitmap") }
+        try Raster.write(image, to: url, format: .png, quality: 1, metadata: nil)
+    }
+
+    private static func makeWAV(at url: URL) throws {
+        let sampleRate = 22050
+        let seconds = 0.6
+        let sampleCount = Int(Double(sampleRate) * seconds)
+        var samples = Data()
+        for index in 0..<sampleCount {
+            let value = sin(2 * Double.pi * 440 * Double(index) / Double(sampleRate)) * 0.3
+            var little = Int16(value * Double(Int16.max)).littleEndian
+            samples.append(Data(bytes: &little, count: 2))
+        }
+
+        var data = Data()
+        func append(_ string: String) { data.append(Data(string.utf8)) }
+        func append(_ value: UInt32) { var v = value.littleEndian; data.append(Data(bytes: &v, count: 4)) }
+        func append(_ value: UInt16) { var v = value.littleEndian; data.append(Data(bytes: &v, count: 2)) }
+
+        append("RIFF")
+        append(UInt32(36 + samples.count))
+        append("WAVE")
+        append("fmt ")
+        append(UInt32(16))
+        append(UInt16(1))
+        append(UInt16(1))
+        append(UInt32(sampleRate))
+        append(UInt32(sampleRate * 2))
+        append(UInt16(2))
+        append(UInt16(16))
+        append("data")
+        append(UInt32(samples.count))
+        data.append(samples)
+
+        try data.write(to: url)
+    }
+}
diff --git a/Sources/Konverter/UI/FloatPanel.swift b/Sources/Konverter/UI/FloatPanel.swift
new file mode 100644
index 0000000..d29df31
--- /dev/null
+++ b/Sources/Konverter/UI/FloatPanel.swift
@@ -0,0 +1,232 @@
+import AppKit
+import Foundation
+import PDFKit
+import QuickLookThumbnailing
+import SwiftUI
+
+/// "Float": a borderless preview that hovers over other windows, the same
+/// gesture Tangerine offers from the Control wheel.
+final class FloatPanel: NSObject {
+    static let shared = FloatPanel()
+
+    private var window: NSWindow?
+    private var urls: [URL] = []
+    private var index = 0
+
+    private override init() { super.init() }
+
+    @MainActor
+    func show(urls: [URL]) {
+        self.urls = urls
+        index = 0
+        let window = ensureWindow()
+        if let screen = NSScreen.screens.first(where: { $0.frame.contains(NSEvent.mouseLocation) }) ?? NSScreen.main {
+            let frame = screen.visibleFrame
+            let size = CGSize(width: 420, height: 320)
+            window.setContentSize(size)
+            window.setFrameOrigin(CGPoint(
+                x: min(max(frame.minX + 16, NSEvent.mouseLocation.x - size.width / 2), frame.maxX - size.width - 16),
+                y: min(max(frame.minY + 16, NSEvent.mouseLocation.y - size.height - 24), frame.maxY - size.height - 16)
+            ))
+        }
+        window.alphaValue = 0
+        window.orderFrontRegardless()
+        NSAnimationContext.runAnimationGroup { context in
+            context.duration = 0.18
+            window.animator().alphaValue = 1
+        }
+        render()
+    }
+
+    @MainActor
+    private func ensureWindow() -> NSWindow {
+        if let window { return window }
+        let window = OverlayWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 420, height: 320),
+            styleMask: [.borderless],
+            backing: .buffered,
+            defer: false
+        )
+        window.isOpaque = false
+        window.backgroundColor = .clear
+        window.hasShadow = true
+        window.level = .floating
+        window.isMovableByWindowBackground = true
+        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
+        window.contentView = NSHostingView(rootView: FloatView(controller: self))
+        self.window = window
+        return window
+    }
+
+    @MainActor
+    func render() {
+        guard let window, let content = window.contentView as? NSHostingView<FloatView> else { return }
+        content.rootView = FloatView(controller: self)
+    }
+
+    @MainActor
+    func close() {
+        guard let window else { return }
+        NSAnimationContext.runAnimationGroup { context in
+            context.duration = 0.15
+            window.animator().alphaValue = 0
+        } completionHandler: {
+            window.orderOut(nil)
+        }
+        urls = []
+    }
+
+    @MainActor
+    func step(_ delta: Int) {
+        guard !urls.isEmpty else { return }
+        index = ((index + delta) % urls.count + urls.count) % urls.count
+        render()
+    }
+
+    var currentURL: URL? {
+        urls.indices.contains(index) ? urls[index] : nil
+    }
+
+    var counter: String? {
+        urls.count > 1 ? "\(index + 1) of \(urls.count)" : nil
+    }
+
+    @MainActor
+    func openInDefaultApp() {
+        guard let url = currentURL else { return }
+        NSWorkspace.shared.open(url)
+    }
+
+    @MainActor
+    func reveal() {
+        guard let url = currentURL else { return }
+        NSWorkspace.shared.activateFileViewerSelecting([url])
+    }
+}
+
+struct FloatView: View {
+    let controller: FloatPanel
+
+    @State private var image: NSImage?
+    @State private var failure: String?
+    @State private var isLoading = true
+
+    var body: some View {
+        VStack(spacing: 0) {
+            Group {
+                if let image {
+                    Image(nsImage: image)
+                        .resizable()
+                        .aspectRatio(contentMode: .fit)
+                        .padding(10)
+                } else if let failure {
+                    VStack(spacing: 6) {
+                        Image(systemName: "eye.slash")
+                            .font(.system(size: 22))
+                        Text(failure)
+                            .font(.system(size: 11))
+                            .multilineTextAlignment(.center)
+                    }
+                    .foregroundStyle(.secondary)
+                    .padding()
+                } else {
+                    ProgressView()
+                }
+            }
+            .frame(maxWidth: .infinity, maxHeight: .infinity)
+
+            Divider().opacity(0.35)
+
+            HStack(spacing: 10) {
+                Image(systemName: "doc")
+                    .font(.system(size: 11))
+                Text(controller.currentURL?.lastPathComponent ?? "")
+                    .font(.system(size: 11, weight: .medium))
+                    .lineLimit(1)
+                    .truncationMode(.middle)
+                if let counter = controller.counter {
+                    Text(counter)
+                        .font(.system(size: 10))
+                        .foregroundStyle(.secondary)
+                }
+                Spacer()
+                Button {
+                    controller.step(-1)
+                } label: { Image(systemName: "chevron.left") }
+                    .buttonStyle(.plain)
+                Button {
+                    controller.step(1)
+                } label: { Image(systemName: "chevron.right") }
+                    .buttonStyle(.plain)
+                Button("Open") { controller.openInDefaultApp() }
+                    .buttonStyle(.plain)
+                    .font(.system(size: 11, weight: .medium))
+                    .foregroundStyle(Color.accentColor)
+                Button {
+                    controller.close()
+                } label: { Image(systemName: "xmark") }
+                    .buttonStyle(.plain)
+            }
+            .padding(.horizontal, 12)
+            .padding(.vertical, 8)
+        }
+        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 14, style: .continuous))
+        .overlay(
+            RoundedRectangle(cornerRadius: 14, style: .continuous)
+                .strokeBorder(Color.primary.opacity(0.1))
+        )
+        .task(id: controller.currentURL) {
+            await load()
+        }
+    }
+
+    private func load() async {
+        guard let url = controller.currentURL else {
+            image = nil
+            failure = "Nothing to preview"
+            isLoading = false
+            return
+        }
+        isLoading = true
+        failure = nil
+
+        // Images and PDFs get a real render; everything else falls back to a
+        // Quick Look thumbnail.
+        if FileKind.category(of: url) == .image, let loaded = NSImage(contentsOf: url) {
+            image = loaded
+            isLoading = false
+            return
+        }
+        if url.pathExtension.lowercased() == "pdf", let page = PDFKitPreview.image(for: url) {
+            image = page
+            isLoading = false
+            return
+        }
+
+        let request = QLThumbnailGenerator.Request(
+            fileAt: url,
+            size: CGSize(width: 900, height: 700),
+            scale: NSScreen.main?.backingScaleFactor ?? 2,
+            representationTypes: .all
+        )
+        let representation = try? await QLThumbnailGenerator.shared.generateBestRepresentation(for: request)
+        if let cgImage = representation?.cgImage {
+            image = NSImage(cgImage: cgImage, size: NSSize(width: cgImage.width / 2, height: cgImage.height / 2))
+        } else {
+            image = nil
+            failure = "No preview available for .\(url.pathExtension)"
+        }
+        isLoading = false
+    }
+}
+
+enum PDFKitPreview {
+    static func image(for url: URL) -> NSImage? {
+        guard let document = PDFDocument(url: url), let page = document.page(at: 0) else { return nil }
+        let bounds = page.bounds(for: .mediaBox)
+        let scale: CGFloat = 1.6
+        let size = CGSize(width: bounds.width * scale, height: bounds.height * scale)
+        let thumbnail = page.thumbnail(of: size, for: .mediaBox)
+        return thumbnail
+    }
+}
diff --git a/Sources/Konverter/UI/JobPanel.swift b/Sources/Konverter/UI/JobPanel.swift
new file mode 100644
index 0000000..75c75dc
--- /dev/null
+++ b/Sources/Konverter/UI/JobPanel.swift
@@ -0,0 +1,254 @@
+import AppKit
+import SwiftUI
+
+/// The small job window. Tangerine opens one per job; a single stack that
+/// shows every job is less noisy and can be dismissed in one click.
+final class JobPanelController: NSObject {
+    static let shared = JobPanelController()
+
+    private var panel: NSPanel?
+
+    private override init() { super.init() }
+
+    func refresh(store: JobStore) {
+        guard Thread.isMainThread else {
+            DispatchQueue.main.async { self.refresh(store: store) }
+            return
+        }
+        guard Settings.shared.showProgressWindow else { return }
+        guard !store.jobs.isEmpty else {
+            panel?.orderOut(nil)
+            panel = nil
+            return
+        }
+
+        let panel = ensurePanel()
+        if !panel.isVisible {
+            position(panel, near: store.jobs.last?.origin)
+            panel.alphaValue = 0
+            panel.orderFrontRegardless()
+            NSAnimationContext.runAnimationGroup { context in
+                context.duration = 0.18
+                panel.animator().alphaValue = 1
+            }
+        }
+    }
+
+    func dismissIfAllFinished(store: JobStore) {
+        guard store.activeCount == 0 else { return }
+        let work = DispatchWorkItem { [weak self] in
+            guard let self, let panel = self.panel, JobStore.shared.activeCount == 0 else { return }
+            NSAnimationContext.runAnimationGroup { context in
+                context.duration = 0.2
+                panel.animator().alphaValue = 0
+            } completionHandler: {
+                panel.orderOut(nil)
+                JobStore.shared.dismissFinished()
+                self.panel = nil
+            }
+        }
+        DispatchQueue.main.asyncAfter(deadline: .now() + 1.6, execute: work)
+    }
+
+    func show() {
+        refresh(store: .shared)
+    }
+
+    private func ensurePanel() -> NSPanel {
+        if let panel { return panel }
+        let panel = NSPanel(
+            contentRect: NSRect(x: 0, y: 0, width: 320, height: 120),
+            styleMask: [.borderless, .nonactivatingPanel],
+            backing: .buffered,
+            defer: false
+        )
+        panel.isFloatingPanel = true
+        panel.level = .floating
+        panel.isOpaque = false
+        panel.backgroundColor = .clear
+        panel.hasShadow = true
+        panel.hidesOnDeactivate = false
+        panel.becomesKeyOnlyIfNeeded = true
+        panel.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
+        panel.contentView = NSHostingView(rootView: JobsView(store: .shared))
+        self.panel = panel
+        return panel
+    }
+
+    private func position(_ panel: NSPanel, near origin: CGPoint?) {
+        let size = panel.contentView?.fittingSize ?? CGSize(width: 320, height: 140)
+        panel.setContentSize(size)
+
+        let screen = NSScreen.screens.first { $0.frame.contains(origin ?? .zero) } ?? NSScreen.main
+        guard let frame = screen?.visibleFrame else { return }
+
+        var point = CGPoint(x: frame.midX - size.width / 2, y: frame.minY + 80)
+        if let origin {
+            point = CGPoint(x: origin.x + 26, y: origin.y - size.height / 2)
+        }
+        point.x = min(max(frame.minX + 12, point.x), frame.maxX - size.width - 12)
+        point.y = min(max(frame.minY + 12, point.y), frame.maxY - size.height - 12)
+        panel.setFrameOrigin(point)
+    }
+
+    /// Re-centres and resizes once the content changes.
+    func layout() {
+        guard let panel, panel.isVisible else { return }
+        let size = panel.contentView?.fittingSize ?? panel.frame.size
+        let anchor = CGPoint(x: panel.frame.minX, y: panel.frame.midY)
+        panel.setContentSize(size)
+        panel.setFrameOrigin(CGPoint(x: anchor.x, y: anchor.y - size.height / 2))
+    }
+}
+
+struct JobsView: View {
+    @ObservedObject var store: JobStore
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            HStack(spacing: 6) {
+                Image(systemName: "arrow.triangle.2.circlepath")
+                    .font(.system(size: 11, weight: .semibold))
+                Text(store.activeCount > 0 ? "Working…" : "Finished")
+                    .font(.system(size: 11, weight: .semibold))
+                Spacer()
+                Button {
+                    store.cancelAll()
+                } label: {
+                    Image(systemName: "stop.circle")
+                }
+                .buttonStyle(.plain)
+                .help("Cancel everything")
+                .opacity(store.activeCount > 0 ? 1 : 0)
+                Button {
+                    store.dismissFinished()
+                    JobPanelController.shared.performClose()
+                } label: {
+                    Image(systemName: "xmark.circle")
+                }
+                .buttonStyle(.plain)
+                .help("Close")
+            }
+            .padding(.horizontal, 12)
+            .padding(.top, 10)
+            .padding(.bottom, 6)
+
+            Divider().opacity(0.4)
+
+            ScrollView {
+                VStack(alignment: .leading, spacing: 8) {
+                    ForEach(store.jobs) { job in
+                        JobRow(job: job, store: store)
+                    }
+                }
+                .padding(12)
+            }
+            .frame(maxHeight: 260)
+        }
+        .frame(width: 320)
+        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 14, style: .continuous))
+        .overlay(
+            RoundedRectangle(cornerRadius: 14, style: .continuous)
+                .strokeBorder(Color.primary.opacity(0.09))
+        )
+        .onReceive(store.$jobs) { _ in
+            DispatchQueue.main.async {
+                JobPanelController.shared.layout()
+            }
+        }
+    }
+}
+
+private struct JobRow: View {
+    let job: Job
+    @ObservedObject var store: JobStore
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 4) {
+            HStack(spacing: 6) {
+                Image(systemName: symbol)
+                    .font(.system(size: 11, weight: .semibold))
+                    .foregroundStyle(tint)
+                Text(job.title)
+                    .font(.system(size: 11.5, weight: .medium))
+                    .lineLimit(1)
+                    .truncationMode(.middle)
+                Spacer(minLength: 4)
+                if job.status == .running {
+                    Button {
+                        store.cancel(job.id)
+                    } label: {
+                        Image(systemName: "xmark")
+                            .font(.system(size: 9, weight: .bold))
+                    }
+                    .buttonStyle(.plain)
+                    .help("Cancel this job")
+                } else {
+                    Button {
+                        store.remove(job.id)
+                    } label: {
+                        Image(systemName: "trash")
+                            .font(.system(size: 9))
+                    }
+                    .buttonStyle(.plain)
+                    .help("Remove")
+                }
+            }
+
+            if job.status == .running {
+                ProgressView(value: max(0.02, job.progress))
+                    .progressViewStyle(.linear)
+            }
+
+            HStack(spacing: 6) {
+                Text(detail)
+                    .font(.system(size: 10))
+                    .foregroundStyle(.secondary)
+                    .lineLimit(2)
+                Spacer(minLength: 4)
+                if !job.outputs.isEmpty, job.status == .finished {
+                    Button("Reveal") {
+                        NSWorkspace.shared.activateFileViewerSelecting(job.outputs)
+                    }
+                    .buttonStyle(.plain)
+                    .font(.system(size: 10, weight: .medium))
+                    .foregroundStyle(Color.accentColor)
+                }
+            }
+        }
+    }
+
+    private var detail: String {
+        if let error = job.errorMessage { return error }
+        if job.sourceCount > 1, job.status == .finished, !job.outputs.isEmpty {
+            return "\(job.outputs.count) files written"
+        }
+        return job.detail.isEmpty ? job.title : job.detail
+    }
+
+    private var symbol: String {
+        switch job.status {
+        case .running: return "hourglass"
+        case .finished: return "checkmark.circle.fill"
+        case .failed: return "exclamationmark.triangle.fill"
+        case .cancelled: return "slash.circle"
+        }
+    }
+
+    private var tint: Color {
+        switch job.status {
+        case .running: return .secondary
+        case .finished: return .green
+        case .failed: return .orange
+        case .cancelled: return .secondary
+        }
+    }
+}
+
+extension JobPanelController {
+    func performClose() {
+        panel?.orderOut(nil)
+        panel = nil
+        JobStore.shared.dismissFinished()
+    }
+}
diff --git a/Sources/Konverter/UI/MenuBar.swift b/Sources/Konverter/UI/MenuBar.swift
new file mode 100644
index 0000000..3b8088a
--- /dev/null
+++ b/Sources/Konverter/UI/MenuBar.swift
@@ -0,0 +1,113 @@
+import AppKit
+import Foundation
+
+/// The menu bar item: the app's only permanent UI, and the place to turn the
+/// wheel off or fall back to picking files by hand.
+final class MenuBarController: NSObject, NSMenuDelegate {
+    private var statusItem: NSStatusItem?
+
+    func install() {
+        let item = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
+        if let button = item.button {
+            let image = NSImage(systemSymbolName: "arrow.triangle.2.circlepath", accessibilityDescription: "Konverter")
+            image?.isTemplate = true
+            button.image = image
+            button.setAccessibilityLabel("Konverter")
+        }
+        let menu = NSMenu()
+        menu.delegate = self
+        item.menu = menu
+        statusItem = item
+        rebuild(menu)
+    }
+
+    func menuNeedsUpdate(_ menu: NSMenu) {
+        rebuild(menu)
+    }
+
+    private func rebuild(_ menu: NSMenu) {
+        menu.removeAllItems()
+
+        let enabled = Settings.shared.enabled
+        let toggle = NSMenuItem(
+            title: enabled ? "Konverter Active" : "Konverter Paused",
+            action: #selector(toggleEnabled),
+            keyEquivalent: ""
+        )
+        toggle.target = self
+        toggle.state = enabled ? .on : .off
+        menu.addItem(toggle)
+
+        menu.addItem(.separator())
+
+        let convert = NSMenuItem(title: "Konvert Files…", action: #selector(convertFiles), keyEquivalent: "o")
+        convert.target = self
+        menu.addItem(convert)
+
+        let jobs = NSMenuItem(title: "Show Jobs", action: #selector(showJobs), keyEquivalent: "j")
+        jobs.target = self
+        menu.addItem(jobs)
+
+        menu.addItem(.separator())
+
+        let settings = NSMenuItem(title: "Settings…", action: #selector(showSettings), keyEquivalent: ",")
+        settings.target = self
+        menu.addItem(settings)
+
+        let about = NSMenuItem(title: "About Konverter", action: #selector(showAbout), keyEquivalent: "")
+        about.target = self
+        menu.addItem(about)
+
+        menu.addItem(.separator())
+
+        let quit = NSMenuItem(title: "Quit Konverter", action: #selector(NSApplication.terminate(_:)), keyEquivalent: "q")
+        quit.target = NSApp
+        menu.addItem(quit)
+    }
+
+    @objc private func toggleEnabled() {
+        Settings.shared.enabled.toggle()
+        if !Settings.shared.enabled {
+            WheelController.shared.cancel()
+        }
+        if let menu = statusItem?.menu {
+            rebuild(menu)
+        }
+    }
+
+    @objc private func convertFiles() {
+        let panel = NSOpenPanel()
+        panel.canChooseFiles = true
+        panel.canChooseDirectories = true
+        panel.allowsMultipleSelection = true
+        panel.prompt = "Choose"
+        panel.message = "Pick files to convert, then choose an output format"
+        NSApp.activate(ignoringOtherApps: true)
+        guard panel.runModal() == .OK, !panel.urls.isEmpty else { return }
+        // Let the panel close before the menu opens over it.
+        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
+            QuickMenu.show(urls: panel.urls, at: NSEvent.mouseLocation)
+        }
+    }
+
+    @objc private func showJobs() {
+        JobStore.shared.panelVisible = true
+        JobPanelController.shared.show()
+    }
+
+    @objc private func showSettings() {
+        PreferencesWindowController.shared.show()
+    }
+
+    @objc private func showAbout() {
+        NSApp.activate(ignoringOtherApps: true)
+        NSApp.orderFrontStandardAboutPanel(options: [
+            .applicationName: "Konverter",
+            .applicationVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0",
+            .credits: NSAttributedString(
+                string: "Drag a file in Finder, then hold a key.\nShift converts · Command shows tools · Control shows file actions.\nEverything runs on this Mac.",
+                attributes: [.font: NSFont.systemFont(ofSize: 11)]
+            )
+        ])
+    }
+}
diff --git a/Sources/Konverter/UI/Notifier.swift b/Sources/Konverter/UI/Notifier.swift
new file mode 100644
index 0000000..7c0746f
--- /dev/null
+++ b/Sources/Konverter/UI/Notifier.swift
@@ -0,0 +1,88 @@
+import AppKit
+import Foundation
+import SwiftUI
+
+/// Small, non-modal confirmations ("Path copied", "3 files converted").
+/// Nothing here blocks the user's flow, which is the whole point of the app.
+enum Notifier {
+    private static var toastWindow: NSWindow?
+    private static var dismissWorkItem: DispatchWorkItem?
+
+    @MainActor
+    static func flash(title: String, body: String? = nil, symbol: String = "checkmark.circle.fill") {
+        guard Settings.shared.showProgressWindow else { return }
+        show(title: title, body: body, symbol: symbol, tone: .success, duration: 2.0)
+    }
+
+    @MainActor
+    static func error(_ title: String, _ message: String) {
+        show(title: title, body: message, symbol: "exclamationmark.triangle.fill", tone: .failure, duration: 6.0)
+    }
+
+    private enum Tone { case success, failure }
+
+    @MainActor
+    private static func show(title: String, body: String?, symbol: String, tone: Tone, duration: TimeInterval) {
+        dismissWorkItem?.cancel()
+        toastWindow?.close()
+
+        let accent: Color = tone == .success ? .green : .orange
+        let view = HStack(spacing: 10) {
+            Image(systemName: symbol)
+                .font(.system(size: 16, weight: .semibold))
+                .foregroundStyle(accent)
+            VStack(alignment: .leading, spacing: 2) {
+                Text(title)
+                    .font(.system(size: 12, weight: .semibold))
+                    .lineLimit(1)
+                if let body, !body.isEmpty {
+                    Text(body)
+                        .font(.system(size: 11))
+                        .foregroundStyle(.secondary)
+                        .lineLimit(2)
+                        .truncationMode(.middle)
+                }
+            }
+        }
+        .padding(.horizontal, 14)
+        .padding(.vertical, 10)
+        .frame(minWidth: 220, maxWidth: 420, alignment: .leading)
+        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 12, style: .continuous))
+        .overlay(
+            RoundedRectangle(cornerRadius: 12, style: .continuous)
+                .strokeBorder(Color.primary.opacity(0.08))
+        )
+
+        let controller = NSHostingController(rootView: view)
+        let window = NSWindow(contentViewController: controller)
+        window.styleMask = [.borderless]
+        window.isOpaque = false
+        window.backgroundColor = .clear
+        window.hasShadow = true
+        window.level = .statusBar
+        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary, .stationary]
+        window.ignoresMouseEvents = true
+        window.appearance = NSApp.effectiveAppearance
+
+        let size = controller.view.fittingSize
+        let screen = NSScreen.main ?? NSScreen.screens.first
+        if let frame = screen?.visibleFrame {
+            let origin = CGPoint(x: frame.midX - size.width / 2, y: frame.minY + 96)
+            window.setFrame(CGRect(origin: origin, size: size), display: true)
+        }
+        window.orderFrontRegardless()
+        toastWindow = window
+
+        let work = DispatchWorkItem { [weak window] in
+            NSAnimationContext.runAnimationGroup { context in
+                context.duration = 0.25
+                window?.animator().alphaValue = 0
+            } completionHandler: {
+                window?.close()
+            }
+            if toastWindow === window { toastWindow = nil }
+        }
+        dismissWorkItem = work
+        DispatchQueue.main.asyncAfter(deadline: .now() + duration, execute: work)
+    }
+}
diff --git a/Sources/Konverter/UI/OptionsWindow.swift b/Sources/Konverter/UI/OptionsWindow.swift
new file mode 100644
index 0000000..60842f5
--- /dev/null
+++ b/Sources/Konverter/UI/OptionsWindow.swift
@@ -0,0 +1,190 @@
+import AppKit
+import SwiftUI
+
+/// The form a tool needs before it can run (quality, trim points, password …).
+/// Values are remembered per tool, so the second time is still one drop.
+final class OptionsWindowController: NSObject {
+    static let shared = OptionsWindowController()
+
+    private var window: NSWindow?
+    private var tool: ToolID?
+    private var urls: [URL] = []
+    private var origin: CGPoint?
+    private var params = ToolParams()
+
+    private override init() { super.init() }
+
+    func present(tool: ToolID, urls: [URL], origin: CGPoint?) {
+        self.tool = tool
+        self.urls = urls
+        self.origin = origin
+        params = Settings.shared.params(for: tool)
+        params.fillMissing(from: tool)
+
+        let view = OptionsView(
+            tool: tool,
+            params: params,
+            fileCount: urls.count,
+            onApply: { [weak self] values in self?.apply(values) },
+            onCancel: { [weak self] in self?.close() }
+        )
+
+        close()
+        let window = NSWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 340, height: 120),
+            styleMask: [.titled, .closable, .fullSizeContentView],
+            backing: .buffered,
+            defer: false
+        )
+        window.title = tool.title
+        window.titlebarAppearsTransparent = true
+        window.isMovableByWindowBackground = true
+        window.level = .floating
+        window.contentView = NSHostingView(rootView: view)
+        window.center()
+        if let origin, let screen = NSScreen.screens.first(where: { $0.frame.contains(origin) }) ?? NSScreen.main {
+            let frame = screen.visibleFrame
+            window.setFrameOrigin(CGPoint(
+                x: min(max(frame.minX + 20, origin.x - 170), frame.maxX - 360),
+                y: min(max(frame.minY + 20, origin.y - 180), frame.maxY - 220)
+            ))
+        }
+        NSApp.activate(ignoringOtherApps: true)
+        window.makeKeyAndOrderFront(nil)
+        self.window = window
+    }
+
+    private func apply(_ values: ToolParams) {
+        guard let tool else { return }
+        Settings.shared.store(params: values, for: tool)
+        let captured = urls
+        let point = origin
+        close()
+        JobStore.shared.submit(urls: captured, target: .tool(tool), params: values, origin: point)
+    }
+
+    private func close() {
+        window?.orderOut(nil)
+        window = nil
+    }
+}
+
+struct OptionsView: View {
+    let tool: ToolID
+    let fileCount: Int
+    let onApply: (ToolParams) -> Void
+    let onCancel: () -> Void
+
+    @State private var values: [String: String] = [:]
+
+    init(
+        tool: ToolID,
+        params: ToolParams,
+        fileCount: Int,
+        onApply: @escaping (ToolParams) -> Void,
+        onCancel: @escaping () -> Void
+    ) {
+        self.tool = tool
+        self.fileCount = fileCount
+        self.onApply = onApply
+        self.onCancel = onCancel
+        var initial: [String: String] = [:]
+        for field in tool.fields {
+            initial[field.id] = params[field.id] ?? field.defaultValue
+        }
+        _values = State(initialValue: initial)
+    }
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 12) {
+            HStack(spacing: 8) {
+                Image(systemName: tool.symbol)
+                    .font(.system(size: 15, weight: .semibold))
+                    .foregroundStyle(Color.accentColor)
+                VStack(alignment: .leading, spacing: 1) {
+                    Text(tool.title)
+                        .font(.system(size: 13, weight: .semibold))
+                    Text(fileCount == 1 ? "1 file" : "\(fileCount) files")
+                        .font(.system(size: 10.5))
+                        .foregroundStyle(.secondary)
+                }
+            }
+
+            ForEach(tool.fields) { field in
+                fieldView(field)
+            }
+
+            HStack {
+                Spacer()
+                Button("Cancel", action: onCancel)
+                    .keyboardShortcut(.cancelAction)
+                Button("Apply") {
+                    var params = ToolParams()
+                    for (key, value) in values { params[key] = value }
+                    onApply(params)
+                }
+                .keyboardShortcut(.defaultAction)
+            }
+        }
+        .padding(16)
+        .frame(width: 340)
+    }
+
+    @ViewBuilder
+    private func fieldView(_ field: ToolField) -> some View {
+        VStack(alignment: .leading, spacing: 3) {
+            HStack {
+                Text(field.label)
+                    .font(.system(size: 11, weight: .medium))
+                Spacer()
+                if let unit = field.unit {
+                    Text(unit)
+                        .font(.system(size: 10))
+                        .foregroundStyle(.secondary)
+                }
+            }
+            control(for: field)
+            if let help = field.help {
+                Text(help)
+                    .font(.system(size: 9.5))
+                    .foregroundStyle(.secondary)
+            }
+        }
+    }
+
+    @ViewBuilder
+    private func control(for field: ToolField) -> some View {
+        let binding = Binding<String>(
+            get: { values[field.id] ?? field.defaultValue },
+            set: { values[field.id] = $0 }
+        )
+
+        switch field.kind {
+        case .text:
+            TextField("", text: binding)
+                .textFieldStyle(.roundedBorder)
+        case .secret:
+            SecureField("", text: binding)
+                .textFieldStyle(.roundedBorder)
+        case .toggle:
+            Toggle("", isOn: Binding(
+                get: { (values[field.id] ?? field.defaultValue) == "true" },
+                set: { values[field.id] = $0 ? "true" : "false" }
+            ))
+            .labelsHidden()
+            .toggleStyle(.switch)
+        case .choice(let options):
+            Picker("", selection: binding) {
+                ForEach(options, id: \.self) { option in
+                    Text(option).tag(option)
+                }
+            }
+            .labelsHidden()
+            .pickerStyle(.menu)
+        case .integer, .decimal, .timecode:
+            TextField("", text: binding)
+                .textFieldStyle(.roundedBorder)
+                .font(.system(size: 12, design: .monospaced))
+        }
+    }
+}
diff --git a/Sources/Konverter/UI/PreferencesWindow.swift b/Sources/Konverter/UI/PreferencesWindow.swift
new file mode 100644
index 0000000..d1c94a1
--- /dev/null
+++ b/Sources/Konverter/UI/PreferencesWindow.swift
@@ -0,0 +1,224 @@
+import AppKit
+import SwiftUI
+
+/// Settings window. Also the place where the active conversion engines are
+/// listed, so "why can't I export MKV?" has an answer in the app itself.
+final class PreferencesWindowController {
+    static let shared = PreferencesWindowController()
+
+    private var window: NSWindow?
+
+    private init() {}
+
+    func show() {
+        if let window {
+            NSApp.activate(ignoringOtherApps: true)
+            window.makeKeyAndOrderFront(nil)
+            return
+        }
+        let window = NSWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 520, height: 620),
+            styleMask: [.titled, .closable, .fullSizeContentView],
+            backing: .buffered,
+            defer: false
+        )
+        window.title = "Konverter Settings"
+        window.titlebarAppearsTransparent = true
+        window.contentView = NSHostingView(rootView: PreferencesView())
+        window.center()
+        window.isReleasedWhenClosed = false
+        NSApp.activate(ignoringOtherApps: true)
+        window.makeKeyAndOrderFront(nil)
+        self.window = window
+    }
+}
+
+struct PreferencesView: View {
+    @ObservedObject private var settings = Settings.shared
+    @State private var loginItemError: String?
+
+    var body: some View {
+        TabView {
+            general.tabItem { Label("General", systemImage: "gearshape") }
+            wheel.tabItem { Label("Wheel", systemImage: "circle.hexagongrid") }
+            engines.tabItem { Label("Engines", systemImage: "cpu") }
+        }
+        .padding(16)
+        .frame(width: 520, height: 600)
+    }
+
+    private var general: some View {
+        Form {
+            Section {
+                Toggle("Konverter is active", isOn: $settings.enabled)
+                Toggle("Enable at login", isOn: Binding(
+                    get: { settings.openAtLogin },
+                    set: { value in
+                        if LoginItem.set(value) {
+                            settings.openAtLogin = value
+                            loginItemError = nil
+                        } else {
+                            settings.openAtLogin = LoginItem.isEnabled
+                            loginItemError = "Could not update the login item. Move Konverter to /Applications and try again."
+                        }
+                    }
+                ))
+                if let loginItemError {
+                    Text(loginItemError)
+                        .font(.system(size: 10.5))
+                        .foregroundStyle(.orange)
+                }
+            } header: {
+                Text("Startup")
+            }
+
+            Section {
+                Picker("Save converted files", selection: $settings.outputLocation) {
+                    ForEach(OutputLocation.allCases) { location in
+                        Text(location.title).tag(location)
+                    }
+                }
+                if settings.outputLocation == .chosenFolder {
+                    HStack {
+                        Text(settings.outputFolderPath.isEmpty ? "No folder chosen" : settings.outputFolderPath)
+                            .font(.system(size: 11))
+                            .foregroundStyle(.secondary)
+                            .lineLimit(1)
+                            .truncationMode(.middle)
+                        Spacer()
+                        Button("Choose…") { chooseFolder() }
+                    }
+                }
+                Picker("When a file already exists", selection: $settings.conflictPolicy) {
+                    ForEach(ConflictPolicy.allCases) { policy in
+                        Text(policy.title).tag(policy)
+                    }
+                }
+            } header: {
+                Text("Output")
+            }
+
+            Section {
+                Toggle("Show the job window", isOn: $settings.showProgressWindow)
+                Toggle("Reveal files in Finder when finished", isOn: $settings.revealWhenFinished)
+                Toggle("Play a sound when finished", isOn: $settings.playSound)
+            } header: {
+                Text("Feedback")
+            }
+        }
+        .formStyle(.grouped)
+    }
+
+    private var wheel: some View {
+        Form {
+            Section {
+                Picker("Convert", selection: $settings.convertKey) {
+                    ForEach(TriggerKey.allCases) { key in Text(key.title).tag(key) }
+                }
+                Picker("Tools", selection: $settings.toolsKey) {
+                    ForEach(TriggerKey.allCases) { key in Text(key.title).tag(key) }
+                }
+                Picker("Actions", selection: $settings.actionsKey) {
+                    ForEach(TriggerKey.allCases) { key in Text(key.title).tag(key) }
+                }
+                Toggle("Tools also require Shift", isOn: $settings.requireShiftForTools)
+            } header: {
+                Text("Trigger keys")
+            } footer: {
+                Text("Start dragging a file in Finder, then hold a key. The wheel stays open until you drop or press Escape. Keys must differ, otherwise the first match wins (Actions, then Tools, then Convert).")
+                    .font(.system(size: 10.5))
+                    .foregroundStyle(.secondary)
+            }
+
+            Section {
+                Picker("Style", selection: $settings.wheelStyle) {
+                    ForEach(WheelStyle.allCases) { style in Text(style.title).tag(style) }
+                }
+                HStack {
+                    Text("Radius")
+                    Slider(value: $settings.wheelRadius, in: 120...260, step: 4)
+                    Text("\(Int(settings.wheelRadius))")
+                        .font(.system(size: 11, design: .monospaced))
+                        .foregroundStyle(.secondary)
+                        .frame(width: 28)
+                }
+                Toggle("Show labels", isOn: $settings.showLabels)
+                Toggle("Dim the background", isOn: $settings.dimBackground)
+            } header: {
+                Text("Appearance")
+            }
+        }
+        .formStyle(.grouped)
+    }
+
+    private var engines: some View {
+        Form {
+            Section {
+                Toggle("Use external tools", isOn: $settings.useExternalTools)
+                Text("Konverter always works with Apple's frameworks. ffmpeg and LibreOffice only widen the format list.")
+                    .font(.system(size: 10.5))
+                    .foregroundStyle(.secondary)
+            } header: {
+                Text("Conversion engines")
+            }
+
+            Section {
+                engineRow(name: "Core (ImageIO, PDFKit, AVFoundation, textutil)", available: true, detail: "Always available")
+                engineRow(
+                    name: "ffmpeg",
+                    available: Toolchain.hasFFmpeg,
+                    detail: Toolchain.ffmpeg ?? "Install with: brew install ffmpeg"
+                )
+                engineRow(
+                    name: "LibreOffice",
+                    available: Toolchain.hasLibreOffice,
+                    detail: Toolchain.soffice ?? "Install with: brew install --cask libreoffice"
+                )
+            } header: {
+                Text("Detected")
+            }
+
+            Section {
+                Text("Active: \(Toolchain.summary)")
+                    .font(.system(size: 11))
+                if let advice = Toolchain.missingToolAdvice {
+                    Text(advice)
+                        .font(.system(size: 10.5, design: .monospaced))
+                        .foregroundStyle(.secondary)
+                        .textSelection(.enabled)
+                }
+            } header: {
+                Text("Summary")
+            }
+        }
+        .formStyle(.grouped)
+    }
+
+    private func engineRow(name: String, available: Bool, detail: String) -> some View {
+        HStack(alignment: .top, spacing: 8) {
+            Image(systemName: available ? "checkmark.circle.fill" : "circle.dashed")
+                .foregroundStyle(available ? Color.green : Color.secondary)
+                .font(.system(size: 12))
+            VStack(alignment: .leading, spacing: 1) {
+                Text(name).font(.system(size: 12, weight: .medium))
+                Text(detail)
+                    .font(.system(size: 10, design: .monospaced))
+                    .foregroundStyle(.secondary)
+                    .textSelection(.enabled)
+            }
+        }
+    }
+
+    private func chooseFolder() {
+        let panel = NSOpenPanel()
+        panel.canChooseFiles = false
+        panel.canChooseDirectories = true
+        panel.canCreateDirectories = true
+        panel.allowsMultipleSelection = false
+        panel.prompt = "Use Folder"
+        NSApp.activate(ignoringOtherApps: true)
+        if panel.runModal() == .OK, let url = panel.url {
+            settings.outputFolderPath = url.path
+        }
+    }
+}
diff --git a/Sources/Konverter/UI/QuickMenu.swift b/Sources/Konverter/UI/QuickMenu.swift
new file mode 100644
index 0000000..a88734f
--- /dev/null
+++ b/Sources/Konverter/UI/QuickMenu.swift
@@ -0,0 +1,110 @@
+import AppKit
+import Foundation
+
+/// Native menu fallback for the paths where there is no drag to follow: the
+/// menu bar's "Konvert Files…" item and the Finder Quick Action.
+enum QuickMenu {
+    private final class Choice: NSObject {
+        let handler: () -> Void
+
+        init(_ handler: @escaping () -> Void) {
+            self.handler = handler
+        }
+
+        @objc func fire() {
+            handler()
+        }
+    }
+
+    /// The menu items hold their target weakly, so the choices are retained
+    /// here for the duration of the (synchronous) popup.
+    private static var retained: [Choice] = []
+
+    static func show(urls: [URL], at point: CGPoint) {
+        guard !urls.isEmpty else { return }
+        retained.removeAll()
+
+        let menu = NSMenu()
+        menu.autoenablesItems = false
+
+        let header = NSMenuItem(
+            title: WheelBuilder.summary(for: urls),
+            action: nil,
+            keyEquivalent: ""
+        )
+        header.isEnabled = false
+        menu.addItem(header)
+        menu.addItem(.separator())
+
+        let category = FileKind.category(of: urls[0])
+
+        if ConversionCatalog.outputs(for: urls.map { FileKind.category(of: $0) }).isEmpty {
+            let item = NSMenuItem(title: "No conversions for this selection", action: nil, keyEquivalent: "")
+            item.isEnabled = false
+            menu.addItem(item)
+        } else {
+            let convert = NSMenu()
+            for item in WheelBuilder.items(kind: .convert, urls: urls) {
+                let entry = NSMenuItem(title: item.title, action: #selector(Choice.fire), keyEquivalent: "")
+                entry.target = makeChoice {
+                    JobStore.shared.submit(urls: urls, target: .format(format(from: item)))
+                }
+                entry.isEnabled = item.isEnabled
+                if let reason = item.availability.reason { entry.toolTip = reason }
+                convert.addItem(entry)
+            }
+            let submenu = NSMenuItem(title: "Convert", action: nil, keyEquivalent: "")
+            submenu.submenu = convert
+            menu.addItem(submenu)
+        }
+
+        let tools = WheelBuilder.items(kind: .tools, urls: urls)
+        if category != .unknown, !tools.isEmpty {
+            let submenu = NSMenu()
+            for item in tools {
+                guard case .tool(let tool) = item.payload else { continue }
+                let entry = NSMenuItem(title: tool.title, action: #selector(Choice.fire), keyEquivalent: "")
+                entry.target = makeChoice {
+                    if tool.fields.isEmpty {
+                        JobStore.shared.submit(urls: urls, target: .tool(tool))
+                    } else {
+                        OptionsWindowController.shared.present(tool: tool, urls: urls, origin: point)
+                    }
+                }
+                entry.isEnabled = item.isEnabled
+                if let reason = item.availability.reason { entry.toolTip = reason }
+                submenu.addItem(entry)
+            }
+            let wrapper = NSMenuItem(title: "Tools", action: nil, keyEquivalent: "")
+            wrapper.submenu = submenu
+            menu.addItem(wrapper)
+        }
+
+        let actions = NSMenu()
+        for item in WheelBuilder.items(kind: .actions, urls: urls) {
+            guard case .action(let action) = item.payload else { continue }
+            let entry = NSMenuItem(title: action.title, action: #selector(Choice.fire), keyEquivalent: "")
+            entry.target = makeChoice {
+                JobStore.shared.submit(urls: urls, target: .action(action))
+            }
+            actions.addItem(entry)
+        }
+        let actionsWrapper = NSMenuItem(title: "Actions", action: nil, keyEquivalent: "")
+        actionsWrapper.submenu = actions
+        menu.addItem(actionsWrapper)
+
+        menu.popUp(positioning: nil, at: point, in: nil)
+        retained.removeAll()
+    }
+
+    private static func makeChoice(_ handler: @escaping () -> Void) -> Choice {
+        let choice = Choice(handler)
+        retained.append(choice)
+        return choice
+    }
+
+    private static func format(from item: WheelItem) -> Format {
+        if case .format(let format) = item.payload { return format }
+        return .png
+    }
+}
diff --git a/Sources/Konverter/UI/ResultWindow.swift b/Sources/Konverter/UI/ResultWindow.swift
new file mode 100644
index 0000000..5c4ef91
--- /dev/null
+++ b/Sources/Konverter/UI/ResultWindow.swift
@@ -0,0 +1,66 @@
+import AppKit
+import SwiftUI
+
+/// Longer text results (Info, Read QR, Statistics, archive listings).
+final class ResultWindowController {
+    static let shared = ResultWindowController()
+
+    private var window: NSWindow?
+
+    private init() {}
+
+    func show(title: String, body: String) {
+        let view = ResultView(title: title, text: body, onClose: { [weak self] in self?.close() })
+        close()
+
+        let window = NSWindow(
+            contentRect: NSRect(x: 0, y: 0, width: 460, height: 320),
+            styleMask: [.titled, .closable, .resizable, .fullSizeContentView],
+            backing: .buffered,
+            defer: false
+        )
+        window.title = title
+        window.titlebarAppearsTransparent = true
+        window.level = .floating
+        window.contentView = NSHostingView(rootView: view)
+        window.center()
+        NSApp.activate(ignoringOtherApps: true)
+        window.makeKeyAndOrderFront(nil)
+        self.window = window
+    }
+
+    func close() {
+        window?.orderOut(nil)
+        window = nil
+    }
+}
+
+struct ResultView: View {
+    let title: String
+    let text: String
+    let onClose: () -> Void
+
+    var body: some View {
+        VStack(spacing: 0) {
+            ScrollView {
+                Text(text)
+                    .font(.system(size: 11.5, design: .monospaced))
+                    .textSelection(.enabled)
+                    .frame(maxWidth: .infinity, alignment: .leading)
+                    .padding(14)
+            }
+            Divider().opacity(0.4)
+            HStack {
+                Button("Copy") {
+                    NSPasteboard.general.clearContents()
+                    NSPasteboard.general.setString(text, forType: .string)
+                }
+                Spacer()
+                Button("Done", action: onClose)
+                    .keyboardShortcut(.defaultAction)
+            }
+            .padding(10)
+        }
+        .frame(minWidth: 420, minHeight: 260)
+    }
+}
diff --git a/build-app.sh b/build-app.sh
new file mode 100755
index 0000000..f528496
--- /dev/null
+++ b/build-app.sh
@@ -0,0 +1,112 @@
+#!/bin/bash
+# Builds Konverter.app.
+#
+#   ./build-app.sh            # version from git tag, else 0.1.0
+#   ./build-app.sh 1.2.0      # explicit version
+#
+# Signs with the first Developer ID Application identity in the keychain when
+# one exists (needed for notarization), otherwise ad-hoc signs so the bundle
+# still runs locally.
+set -euo pipefail
+cd "$(dirname "$0")"
+
+if [ "${1:-}" != "" ]; then
+    VERSION="$1"
+else
+    VERSION=$(git describe --tags --abbrev=0 2>/dev/null | sed 's/^v//' || true)
+    VERSION="${VERSION:-0.1.0}"
+fi
+
+swift build -c release
+
+BIN=".build/release/Konverter"
+APP="Konverter.app"
+
+if [ ! -x "$BIN" ]; then
+    echo "build-app.sh: $BIN not found after swift build." >&2
+    exit 1
+fi
+
+IDENT=""
+if command -v security >/dev/null 2>&1; then
+    IDENT=$(security find-identity -v -p codesigning 2>/dev/null \
+        | awk '/Developer ID Application:/ { print $2; exit }')
+fi
+
+rm -rf "$APP"
+mkdir -p "$APP/Contents/MacOS" "$APP/Contents/Resources"
+cp "$BIN" "$APP/Contents/MacOS/Konverter"
+printf 'APPL????' > "$APP/Contents/PkgInfo"
+
+cat > "$APP/Contents/Info.plist" <<PLIST
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>CFBundleDevelopmentRegion</key>
+    <string>en</string>
+    <key>CFBundleExecutable</key>
+    <string>Konverter</string>
+    <key>CFBundleIconFile</key>
+    <string>Icon</string>
+    <key>CFBundleIdentifier</key>
+    <string>dev.tzgyn.konverter</string>
+    <key>CFBundleInfoDictionaryVersion</key>
+    <string>6.0</string>
+    <key>CFBundleName</key>
+    <string>Konverter</string>
+    <key>CFBundleDisplayName</key>
+    <string>Konverter</string>
+    <key>CFBundlePackageType</key>
+    <string>APPL</string>
+    <key>CFBundleShortVersionString</key>
+    <string>${VERSION}</string>
+    <key>CFBundleVersion</key>
+    <string>${VERSION}</string>
+    <key>LSMinimumSystemVersion</key>
+    <string>13.0</string>
+    <key>LSUIElement</key>
+    <true/>
+    <key>LSApplicationCategoryType</key>
+    <string>public.app-category.utilities</string>
+    <key>NSHighResolutionCapable</key>
+    <true/>
+    <key>NSPrincipalClass</key>
+    <string>NSApplication</string>
+    <key>NSHumanReadableCopyright</key>
+    <string>Copyright © 2026 Teh Zi Gyn. All rights reserved.</string>
+    <key>NSServices</key>
+    <array>
+        <dict>
+            <key>NSMenuItem</key>
+            <dict>
+                <key>default</key>
+                <string>Convert with Konverter…</string>
+            </dict>
+            <key>NSMessage</key>
+            <string>convertFiles</string>
+            <key>NSPortName</key>
+            <string>Konverter</string>
+            <key>NSSendFileTypes</key>
+            <array>
+                <string>public.item</string>
+            </array>
+            <key>NSRequiredContext</key>
+            <dict/>
+        </dict>
+    </array>
+</dict>
+</plist>
+PLIST
+
+chmod +x scripts/make-icon.sh
+./scripts/make-icon.sh
+
+if [ -n "$IDENT" ]; then
+    security unlock-keychain "$HOME/Library/Keychains/login.keychain-db" 2>/dev/null || true
+    codesign --force --options runtime --timestamp --sign "$IDENT" "$APP"
+    echo "Built $APP $VERSION (signed with Developer ID '$IDENT')"
+else
+    codesign --force --sign - "$APP"
+    echo "Built $APP $VERSION (ad-hoc signed; not distributable)"
+fi
diff --git a/release.sh b/release.sh
new file mode 100755
index 0000000..cf9cf8a
--- /dev/null
+++ b/release.sh
@@ -0,0 +1,95 @@
+#!/bin/bash
+# Builds, signs, notarizes, staples, and zips Konverter for release.
+#
+#   ./release.sh 0.1.0
+#
+# Notarization is required. If it fails, this script fails: do not publish the
+# tag, release, or cask from an unnotarized build.
+set -euo pipefail
+cd "$(dirname "$0")"
+
+if [ "$#" -ne 1 ]; then
+    echo "usage: $0 <version>    e.g. ./release.sh 0.1.0" >&2
+    exit 1
+fi
+VERSION="$1"
+
+APP="Konverter.app"
+ZIP="dist/Konverter.zip"
+
+IDENT=$(security find-identity -v -p codesigning 2>/dev/null \
+    | awk '/Developer ID Application:/ { print $2; exit }')
+if [ -z "$IDENT" ]; then
+    echo "release.sh: no Developer ID Application identity in the keychain." >&2
+    echo "An ad-hoc signed build cannot be notarized; install the certificate first." >&2
+    exit 1
+fi
+
+KEY_PATH="${KONVERTER_NOTARY_API_KEY_PATH:-$HOME/.config/kapture/AuthKey_K5KXMMSB28.p8}"
+KEY_ID="${KONVERTER_NOTARY_API_KEY_ID:-K5KXMMSB28}"
+ISSUER="${KONVERTER_NOTARY_API_ISSUER:-3e25e5dc-8b75-453f-a71c-c7f3feaac628}"
+
+if [ ! -f "$KEY_PATH" ]; then
+    echo "release.sh: notary API key not found at $KEY_PATH" >&2
+    exit 1
+fi
+if ! xcrun --find notarytool >/dev/null 2>&1; then
+    echo "release.sh: xcrun notarytool not found (requires Xcode 13+)." >&2
+    exit 1
+fi
+
+./build-app.sh "$VERSION"
+
+# The zip submitted to Apple must contain the signed bundle only.
+mkdir -p dist
+rm -f "$ZIP"
+ditto -c -k --keepParent "$APP" "$ZIP"
+
+echo "Submitting to Apple for notarization (first run can take minutes)..."
+RESULT=$(mktemp)
+trap 'rm -f "$RESULT"' EXIT
+
+xcrun notarytool submit "$ZIP" \
+    --key "$KEY_PATH" \
+    --key-id "$KEY_ID" \
+    --issuer "$ISSUER" \
+    --wait \
+    --output-format json > "$RESULT"
+
+STATUS=$(/usr/bin/python3 -c 'import json,sys; print(json.load(open(sys.argv[1])).get("status","unknown"))' "$RESULT" 2>/dev/null || echo unknown)
+if [ "$STATUS" != "Accepted" ]; then
+    echo "release.sh: notarization returned '$STATUS' — release aborted." >&2
+    cat "$RESULT" >&2
+    SUBMIT_ID=$(/usr/bin/python3 -c 'import json,sys; print(json.load(open(sys.argv[1])).get("id",""))' "$RESULT" 2>/dev/null || true)
+    if [ -n "$SUBMIT_ID" ]; then
+        echo "Detail:" >&2
+        xcrun notarytool log "$SUBMIT_ID" --key "$KEY_PATH" --key-id "$KEY_ID" --issuer "$ISSUER" >&2 || true
+    fi
+    exit 1
+fi
+
+echo "Notarization accepted — stapling ticket onto the app..."
+xcrun stapler staple "$APP"
+xcrun stapler validate "$APP"
+
+# Re-zip so the distributed archive carries the stapled ticket.
+rm -f "$ZIP"
+ditto -c -k --keepParent "$APP" "$ZIP"
+
+echo "Verifying Gatekeeper assessment..."
+if ! spctl -a -vv "$APP" 2>&1 | grep -q 'source=Notarized Developer ID'; then
+    echo "release.sh: spctl does not report 'source=Notarized Developer ID' — release aborted." >&2
+    spctl -a -vv "$APP" >&2 || true
+    exit 1
+fi
+spctl -a -vv "$APP" 2>&1 | sed 's/^/  /'
+
+echo
+echo "Done — notarized and stapled."
+shasum -a 256 "$ZIP"
+echo
+echo "Publish with:"
+echo "  git tag v$VERSION && git push origin v$VERSION"
+echo "  tea releases create --tag v$VERSION --title \"Konverter $VERSION\" \\"
+echo "    --note \"<what changed>\" --asset $ZIP \\"
+echo "    --repo TZGyn/konverter --login gitea.tzgyn.dev"
diff --git a/scripts/gen-icon.swift b/scripts/gen-icon.swift
new file mode 100644
index 0000000..b863b64
--- /dev/null
+++ b/scripts/gen-icon.swift
@@ -0,0 +1,113 @@
+import AppKit
+
+// Draws the Konverter icon: a warm tangerine squircle with a radial conversion
+// wheel on it. Everything is vector-drawn so the script has no dependencies.
+
+let canvas: CGFloat = 1024
+let size = NSSize(width: canvas, height: canvas)
+guard let rep = NSBitmapImageRep(
+    bitmapDataPlanes: nil, pixelsWide: Int(canvas), pixelsHigh: Int(canvas),
+    bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false,
+    colorSpaceName: .deviceRGB, bytesPerRow: 0, bitsPerPixel: 0
+) else { exit(1) }
+
+NSGraphicsContext.saveGraphicsState()
+NSGraphicsContext.current = NSGraphicsContext(bitmapImageRep: rep)
+NSGraphicsContext.current?.imageInterpolation = .high
+
+let rect = NSRect(origin: .zero, size: size)
+
+// macOS icons live inside a ~10% margin; the squircle fills the rest.
+let body = rect.insetBy(dx: 96, dy: 96)
+let squircle = NSBezierPath(roundedRect: body, xRadius: 200, yRadius: 200)
+
+let gradient = NSGradient(colors: [
+    NSColor(calibratedRed: 1.00, green: 0.66, blue: 0.20, alpha: 1),
+    NSColor(calibratedRed: 0.94, green: 0.33, blue: 0.11, alpha: 1),
+])!
+gradient.draw(in: squircle, angle: -60)
+
+// Soft top highlight.
+NSGraphicsContext.saveGraphicsState()
+squircle.addClip()
+NSGradient(colors: [
+    NSColor.white.withAlphaComponent(0.28),
+    NSColor.white.withAlphaComponent(0.00),
+])!.draw(in: NSRect(x: body.minX, y: body.midY, width: body.width, height: body.height / 2), angle: -90)
+NSGraphicsContext.restoreGraphicsState()
+
+// Radial wheel: eight segments, one of them highlighted as the selection.
+let center = NSPoint(x: rect.midX, y: rect.midY + 24)
+let outer: CGFloat = 296
+let inner: CGFloat = 150
+let segmentCount = 8
+let gap: CGFloat = 3.2
+
+func polar(_ radius: CGFloat, _ degrees: CGFloat) -> NSPoint {
+    let radians = degrees * .pi / 180
+    return NSPoint(x: center.x + radius * cos(radians), y: center.y + radius * sin(radians))
+}
+
+func segment(_ index: Int, from start: CGFloat, to end: CGFloat) -> NSBezierPath {
+    let path = NSBezierPath()
+    path.move(to: polar(inner, start))
+    path.line(to: polar(outer, start))
+    path.appendArc(withCenter: center, radius: outer, startAngle: start, endAngle: end)
+    path.line(to: polar(inner, end))
+    path.appendArc(withCenter: center, radius: inner, startAngle: end, endAngle: start, clockwise: true)
+    path.close()
+    return path
+}
+
+for index in 0..<segmentCount {
+    let centre = 90 - CGFloat(index) * (360 / CGFloat(segmentCount))
+    let start = centre - (360 / CGFloat(segmentCount)) / 2 + gap
+    let end = centre + (360 / CGFloat(segmentCount)) / 2 - gap
+    let path = segment(index, from: start, to: end)
+    // Index 4 sits at -90°, i.e. straight down — where the arrow points.
+    let selected = index == 4
+    (selected ? NSColor.white : NSColor.white.withAlphaComponent(0.34)).setFill()
+    path.fill()
+}
+
+// Hub with a downward arrow: the drop that performs the conversion.
+let hubRadius: CGFloat = 118
+let hubRect = NSRect(
+    x: center.x - hubRadius, y: center.y - hubRadius,
+    width: hubRadius * 2, height: hubRadius * 2
+)
+NSColor(calibratedRed: 0.16, green: 0.10, blue: 0.10, alpha: 0.92).setFill()
+NSBezierPath(ovalIn: hubRect).fill()
+
+NSColor.white.setFill()
+NSBezierPath(ovalIn: hubRect.insetBy(dx: 14, dy: 14)).fill()
+
+// Arrow glyph, pointing at the selected segment.
+let arrow = NSBezierPath()
+let up = center.y + 58
+let down = center.y - 58
+let shaftWidth: CGFloat = 26
+arrow.move(to: NSPoint(x: center.x - shaftWidth / 2, y: up))
+arrow.line(to: NSPoint(x: center.x + shaftWidth / 2, y: up))
+arrow.line(to: NSPoint(x: center.x + shaftWidth / 2, y: down + 30))
+arrow.line(to: NSPoint(x: center.x + 62, y: down + 30))
+arrow.line(to: NSPoint(x: center.x, y: down - 32))
+arrow.line(to: NSPoint(x: center.x - 62, y: down + 30))
+arrow.line(to: NSPoint(x: center.x - shaftWidth / 2, y: down + 30))
+arrow.close()
+arrow.lineJoinStyle = .round
+arrow.lineWidth = 6
+NSColor(calibratedRed: 0.86, green: 0.28, blue: 0.09, alpha: 1).setFill()
+NSColor(calibratedRed: 0.86, green: 0.28, blue: 0.09, alpha: 1).setStroke()
+arrow.fill()
+arrow.stroke()
+
+NSGraphicsContext.restoreGraphicsState()
+
+guard CommandLine.arguments.count >= 2 else { exit(1) }
+guard let data = rep.representation(using: .png, properties: [:]) else { exit(1) }
+do {
+    try data.write(to: URL(fileURLWithPath: CommandLine.arguments[1]))
+} catch {
+    exit(1)
+}
diff --git a/scripts/make-icon.sh b/scripts/make-icon.sh
new file mode 100755
index 0000000..a679518
--- /dev/null
+++ b/scripts/make-icon.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+# Builds Icon.icns from scripts/gen-icon.swift and drops it into Konverter.app.
+# Run ./build-app.sh first (this expects the bundle to exist).
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+APP="Konverter.app"
+if [ ! -d "$APP" ]; then
+    echo "make-icon.sh: $APP not found — run ./build-app.sh first." >&2
+    exit 1
+fi
+
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+
+swift scripts/gen-icon.swift "$TMP/icon-1024.png"
+
+mkdir -p "$TMP/Icon.iconset"
+for s in 16 32 128 256 512; do
+    d=$((s * 2))
+    sips -z "$s" "$s" "$TMP/icon-1024.png" --out "$TMP/Icon.iconset/icon_${s}x${s}.png" >/dev/null
+    sips -z "$d" "$d" "$TMP/icon-1024.png" --out "$TMP/Icon.iconset/icon_${s}x${s}@2x.png" >/dev/null
+done
+
+iconutil -c icns "$TMP/Icon.iconset" -o "$TMP/Icon.icns"
+mkdir -p "$APP/Contents/Resources"
+cp "$TMP/Icon.icns" "$APP/Contents/Resources/Icon.icns"
+echo "Generated $APP/Contents/Resources/Icon.icns"