# Prompt sync server

Small Go service that stores one JSON blob per sync group, keyed by an 8-digit
code (`1234-5678`). There is no authentication: the code is the shared secret,
so anyone who knows it can read and overwrite that group. It is meant to be
self-hosted for personal use, not exposed as a public service.

## Requirements

- Postgres (any recent version; developed against 18)
- A host both Macs can reach — a VPS, a home server, or a Tailscale node

## Run it

```bash
createdb prompt_sync
cd Server
PROMPT_SYNC_DATABASE_URL="postgres://localhost:5432/prompt_sync?sslmode=disable" \
  go run .            # or: go build -o prompt-sync . && ./prompt-sync
```

| Env var | Default |
| --- | --- |
| `PROMPT_SYNC_ADDR` | `:8080` |
| `PROMPT_SYNC_DATABASE_URL` | `postgres://localhost:5432/prompt_sync?sslmode=disable` |

The schema is created on startup. Every request is logged as
`METHOD PATH STATUS DURATION`; SIGTERM/SIGINT shut down gracefully so an
in-flight push is not cut off mid-write.

## Run with Docker

`docker-compose.yml` starts Postgres and the server together:

```bash
cd Server
POSTGRES_PASSWORD=$(openssl rand -hex 16) docker compose up -d
docker compose logs -f server      # request log
```

Or build the image on its own and point it at an existing Postgres:

```bash
docker build -t prompt-sync Server/
docker run -d --name prompt-sync -p 8080:8080 \
  -e PROMPT_SYNC_DATABASE_URL="postgres://user:pass@host:5432/prompt_sync?sslmode=disable" \
  prompt-sync
```

The image is a static binary on `distroless` (non-root, no shell, ~6 MB binary),
so its `HEALTHCHECK` calls `prompt-sync -healthcheck`, which pings the local
`/healthz` and exits non-zero on failure — no curl needed in the image. That is
what `docker ps` reports as the container health.

## Deploy to a Linux host

```bash
# from the repo root, on the Mac
cd Server
GOOS=linux GOARCH=arm64 go build -o prompt-sync .    # amd64 for x86 hosts
scp prompt-sync <host>:/tmp/ && ssh <host> 'sudo mv /tmp/prompt-sync /usr/local/bin/'

# on the host: create the database and role, then
sudo cp Server/prompt-sync.service /etc/systemd/system/
sudo systemctl edit --full prompt-sync   # set PROMPT_SYNC_DATABASE_URL
sudo systemctl enable --now prompt-sync
journalctl -u prompt-sync -f             # verify it is listening
```

Put it behind TLS if it is reachable from the internet — the code is the only
secret, and it travels in the URL path. Both plain HTTP and HTTPS work from the
app; an HTTP URL is often fine over a LAN or Tailscale.

## Endpoints

| Method | Path | Behaviour |
| --- | --- | --- |
| `POST` | `/api/codes` | Generates a unique code, inserts an empty group |
| `GET` | `/api/sync/{code}` | `{"version":N,"updatedAt":…,"data":{…}\|null}`, 404 if unknown |
| `GET` | `/api/sync/{code}/version` | `{"version":N}` — cheap poll used by the app |
| `PUT` | `/api/sync/{code}` | Upserts the payload, returns the incremented version |
| `GET` | `/healthz` | Liveness (200) |

Payloads are opaque `JSONB`; the server never parses note contents. Bodies are
capped at 50 MB, which is generous enough for base64 photos.

## Backups

The whole state is one table, so `pg_dump prompt_sync` is a complete backup:

```bash
pg_dump prompt_sync | gzip > prompt_sync-$(date +%F).sql.gz
```