# package-updater — Claude context

Master/agent fleet updater. A master (UI behind OIDC, Postgres) shows every Compose
stack, Swarm service and container on every machine and starts updates; one agent per
machine (`/var/run/docker.sock` mounted) reports its inventory and runs the jobs.
Both are in one image: `updater-master` and `updater-agent`.

See `README.md` for user-facing docs. This file is for working ON the code.

## Commands

```bash
go test ./...                          # all tests, fast (no docker, no postgres)
go test -race ./internal/agent/... ./internal/master/... ./internal/e2e/
go test -run TestFoo ./internal/master/hub    # single test
go build ./cmd/master ./cmd/agent      # produce ./master and ./agent
docker build -t package-updater:dev .  # multi-stage, builds golang:1.26-alpine

# Postgres tests (store), against any throwaway database:
DATABASE_URL=postgres://... go test -tags integration ./internal/master/store/
```

## Architecture (one-line per package)

- `cmd/master`        — wiring only: config → store → hub → jobs → web, two listeners (UI, agents over pinned TLS)
- `cmd/agent`         — wiring only: config → docker client → inventory → job runner → master connection
- `internal/protocol` — the WebSocket messages both sides speak (`Version`, `JobStart`, `JobResult`, ...)
- `internal/pin`      — master key pair, certificate and fingerprint pinning
- `internal/agenttoken` — agent token generation and hashing
- `internal/imageref` — image reference parsing (repo, tag, digest)
- `internal/logging`  — slog JSON, request-id context propagation
- `internal/agent/config`    — env-var loading; fails fast on missing `MASTER_URL`/`MASTER_KEY`/`AGENT_TOKEN`
- `internal/agent/inventory` — reads Compose, Swarm and plain containers from the Docker daemon
- `internal/agent/conn`      — dial, hello, snapshot, job messages, reconnect with backoff; one writer goroutine per session
- `internal/agent/updater`   — job `Runner` (single FIFO worker, outbox until acked), Compose and Swarm executors, override file, mount-root check, registry auth
- `internal/master/config`   — env-var loading
- `internal/master/store`    — Postgres access and migrations
- `internal/master/hub`      — agent connections: auth, per-connection writer, routing, job reconcile on hello
- `internal/master/jobs`     — decides whether a service may be updated and starts a job on the right agent
- `internal/master/web`, `webauth` — HTMX UI behind OIDC login, SSE signals
- `internal/master/events`   — in-process publish/subscribe for UI refresh signals
- `internal/master/model`    — domain types shared by the above

## Design intent (do not break without discussion)

- **Single FIFO worker per agent by design** (`internal/agent/updater/runner.go`).
  Two `docker compose` calls against the same stack race.
- **One queued or running job per service**, enforced by the unique index
  `update_jobs_one_active` (not by application code).
- **The agent writes exactly one file**, `<stack dir>/compose.override.yaml`, and only
  if it is absent or starts with the header line. It refuses the job when any other
  auto-loaded override name exists.
- **Every config file and the override path must be inside a read-write bind mount of
  the agent's own container whose source equals its destination.** Mounts are read per
  job (`ContainerInspect(SELF_ID)`) and checked after symlink resolution. This replaces
  the old `STACKS_ROOT`.
- **Self-protection on the master**: a service is refused when its image repo equals the
  repo of `AGENT_IMAGE` or the row has the `self` flag. The agent does not re-check.
- **Unknown message types are logged and ignored; malformed messages close the connection.**
- **Reconcile before routable**: the hub fails a reconnecting agent's jobs it does not
  list in `known_jobs`, and only then accepts jobs for that connection.
- **Auth**: agents by token over pinned TLS; people by OIDC. Every state-changing UI
  request is a POST with a CSRF token.

## Gotchas

- **Image matching is case-sensitive.** The tricky case is `localhost:5000/foo:v1` where
  the first colon is a port, not a tag. See `internal/imageref`.
- **Path safety uses `filepath.Rel` + ".." prefix check**, NOT `strings.HasPrefix`.
  Prevents the `/foo-evil` vs `/foo` confusion. See `internal/agent/updater/pathcheck.go`.
- **Go 1.26.3** (`go.mod`). Dockerfile pins `golang:1.26-alpine`. Bumping one
  without the other has caused a fix commit already.
- **`<summary>` C# convention from global CLAUDE.md does not apply here** — this
  is Go. Use idiomatic GoDoc (`// FuncName does X.`).
- **Compose loads only one override file.** Of `compose.override.yml`,
  `compose.override.yaml`, `docker-compose.override.yml`, `docker-compose.override.yaml`
  only the first that exists is read. Hence the refusal described above.
- **Stacks started with explicit `-f` do not load the override on a manual `up`.** The
  agent's own jobs always pass it explicitly.
- **Override entries are never pruned.** A service deleted from the stack file keeps its
  `image:` line in `compose.override.yaml`.
- **There is no `STACKS_ROOT`.** Stack directories must be mounted read-write at the host
  path (`/path:/path`), and `SELF_ID` must resolve to the agent's own container. On Docker
  Desktop/OrbStack bind sources are translated, so Compose jobs fail there.
- **`job.start` carries no paths.** The agent reads working dir and config files from its
  own Docker daemon at execution time.
- **`protocol.Service.ConfigFiles` is the raw comma-joined label string**, so `Service`
  stays comparable with `==` (`inventory.Diff` depends on it).
- **Swarm "succeeded" means the daemon accepted the new spec**, not that tasks converged.
- **Swarm updates need manager-node API access** for the agent doing the update.
- **The image's default entrypoint is `updater-agent`.** The master overrides it with
  `updater-master`. There is no `POST /update` until phase 3.
- **Job output is capped at `protocol.MaxJobOutput` (128 KiB, tail).** NUL bytes are
  stripped by the hub because Postgres text rejects them.

## References

- Master/agent spec: `docs/superpowers/specs/2026-10-12-master-agent-design.md` (authoritative)
- Phase 1 plan: `docs/superpowers/plans/2026-10-12-master-agent-phase-1-inventory.md`
- Phase 2 plan: `docs/superpowers/plans/2026-10-12-master-agent-phase-2-jobs.md`
- Original single-instance design (historical, its webhook is gone until phase 3):
  `docs/superpowers/specs/2026-05-22-package-updater-design.md`
- Consumer-side CI integration: `gitea-action/` (calls `POST /update`, which no longer
  exists until phase 3)

## Conventions

- Conventional Commits (`feat:`, `fix:`, `docs:`, `ci:`, `build:`, `chore:`).
- One package = one responsibility; interfaces defined at consumer site
  (`jobs.Store`, `jobs.Hub`, `conn.Jobs`, `hub.Store`) for testability.
- Table-driven tests with `stretchr/testify`. No mocks beyond hand-written fakes.