Classify worker exit before deciding whether to retry
The worker exits after writing its output but before the acknowledgement frame; automatic retry may produce a second external artifact.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Distributed failure · Idempotency · State machines
Estimated field mix
- Systems programming60%
- Distributed systems40%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional document converter launches local sandbox substitutes as child processes. Its prototype parses newline-delimited output, leaks descriptors, and retries requests after ambiguous worker exits. Create a Rust supervisor and deterministic worker fixtures; no document content or production sandbox is supplied.
Setup prerequisites
- File descriptors
- Framing
- Process signals
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Outcome distinguishes not-started, running, acknowledged, failed, and unknown
- Unknown completion requires status lookup or explicit review
- Retry reuses the stable operation identity
Implementation constraints
- Do not infer failure solely from pipe closure or process exit code.
Verification to include
- Exercise exits before start and after acknowledged completion.
- Exit after effect but before acknowledgement and preserve UNKNOWN without blind retry.
Deliverables
- Exit classification state machine and ambiguity fixtures
Rollout and recovery
Disable automatic retry for unknown outcomes until the worker supports reconciliation.
Value of the work
For the engineer: Practice IPC contracts, resource inheritance, process supervision and ambiguous completion.
For the team: Review a local worker boundary that contains crashes and preserves request outcomes before connecting an isolated execution provider.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.