Tasks, Attempts, Leases, Idempotency, and Recovery

4. Tradeoffs and alternatives

Short leases detect failure quickly but cause false expiry during long tools; long leases delay recovery. Heartbeat cadence, expiry, and reconciliation must reflect operation duration.

Resuming a process can save work but requires trustworthy checkpoints and exactly defined context. Starting a clean Attempt is simpler and more auditable. Mission Control’s V1 Codex adapter correctly declares cancel support without claiming resume.

Automatic retry improves availability for transient failures. It is dangerous for authorization errors, unknown side effects, and deterministic validation failures. Policy should control retry by failure class.

5. Current Mission Control Implementation

At commit b31e27564deb1c03c167e61b5ee094567c2ba7b1, Mission Control models Task Attempts as WorkflowRuns linked by parentTaskId.

The governed scheduler requires an explicit canonical Child Task when one exists. It rejects foreign, cross-workspace, ungoverned, Inbox, Review, Done, and Canceled Tasks. Only Ready-compatible or In Progress Tasks can run. The first dispatch is allowed only with no prior Attempt. Retry requires no active Attempt, the latest failed Attempt, the same Task, and a recovery reason of at least ten characters.

Each successful dispatch appends a WorkflowRun with Attempt and retry numbers. The previous failure remains. Dispatch checks idempotency before event creation, and Task transitions also retain idempotency keys and audited context. The browser evidence for the bounded scheduler demonstrated two Attempts under one Task, retained failure history, reload persistence, and no duplicate Task card.

This is not yet a production lease system. The committed baseline prevents multiple active Attempts through state inspection, but it does not prove an atomic leased worker with heartbeat, fencing token, stale-lease reconciliation, or restart-safe Codex-to-GitHub ownership. Those mechanisms are being developed under todo 024 and must remain Future Vision until committed and verified.