Polish pass hardening the queue and closing plan gaps.
- Task state machine gains `running`: the first heartbeat moves a task from
leased to running (migrations 0006/0007 add the enum value and extend the
lease-integrity check). verifyLease, ExpireLease, the reaper SQL, and job
progress all treat leased and running alike.
- Worker liveness: a heartbeat from a registered worker (UUID worker_id) bumps
its last_heartbeat_at online; a second background reaper marks workers offline
after WORKER_OFFLINE_AFTER of silence (RunReaper generalized to RunPeriodic).
- Request-size limits: JSON bodies capped at 1 MiB; dataset/artifact uploads
capped at MAX_UPLOAD_BYTES (default 1 GiB) via http.MaxBytesReader.
- Tests cover the running transition, liveness + offline reaper (unit over
memstore and integration over Postgres).
Adds the SciMesh coordinator: a durable task-queue server on PostgreSQL
that owns all database access, with workers reaching it over HTTP only.
Structured as a modular monolith following Clean Architecture:
domain entities and their invariants, no I/O
usecase business operations + repository/clock ports
transport HTTP handlers, DTOs, auth, error mapping
storage PostgreSQL repositories, transactions carried in context
infra config, pool, clock, server, lease reaper
Dependencies point strictly inward; domain imports nothing from the module.
Working: layer wiring, routing, shared-token auth, access logging, request
IDs, domain-error to status-code mapping, transactional boundaries,
graceful shutdown (HTTP drain -> reaper stop -> pool close), migrations,
and a Compose stack starting Postgres -> migrations -> coordinator.
The domain is complete and covered by unit tests that need no database:
lease ownership, stale attempts, idempotent result replay, retry budgets,
and lease expiry.
Repository methods are stubs returning ErrNotImplemented (HTTP 501). The
SQL for atomic claiming (FOR UPDATE SKIP LOCKED) and for lease expiry is
written and ready to wire up.
See coordinator/ARCHITECTURE.md for the layer map and a request traced
through every layer.
Efremenko Arhip