feat(tasks): OpenWorkflow-backed TaskEngine, task registry, outbox relay and op-ledger fencing (W1-4)
- TaskEngine port + OpenWorkflowEngine ([email protected].1, schema openworkflow):
enqueue/signal/cancel/get/list/startWorker/stop
- defineTask registry with zod input schema; 9 stub task definitions (§3.1-8)
- TaskContext: step.run/sleep/waitForFact, redacting logger, traceId,
attemptToken, abortSignal driven by PG cancel flag
- signal persists fact to tasks_fact first; waitForFact checks DB before waiting
- OutboxRelay: FOR UPDATE SKIP LOCKED, idempotencyKey outbox:<id>
- withAttemptToken fencing on tasks_op_ledger (own migration, merged in W2)
- tests: kill -9 crash recovery (child worker), cancel, idempotency,
concurrent relays, early fact, lease-loss fencing
Co-Authored-By: Claude Fable 5.1 <[email protected]>
