AGENTS.md@backend/tests · diff

git:20260912.5e85f8a to git:20260920.906c3d4

10 added, 0 removed. Audit A to A.

# Backend Tests

Backend tests must preserve the runtime invariants they exercise without changing production execution topology.

+ ## MCP claim fencing

+ `test_mcp_task_repository.py` covers same-worker reclaim during an in-flight

+ release, poll/cancel snapshot, or notification completion. Use explicit events

+ to pause the old operation at the persistence boundary, reclaim via the real

+ repository, then verify the entire new row remains unchanged. Reclaiming before

+ the old operation starts does not catch SQLite SELECT/ORM-flush races. Keep the

+ old completion timestamp within its original lease so expiry cannot mask a

+ missing token fence; always drain paused tasks and restore session patches.

## Executor starvation tests

`test_executor_starvation.py` covers the deterministic starvation semantics from RFC #4560:

- default-executor saturation and queueing;

- cancellation of an awaiter while an already-started synchronous worker continues;

- isolation between the asyncio default executor and DeerFlow's dedicated file-I/O executor.

Use explicit synchronization such as `threading.Event` rather than sleep-based timing thresholds for worker lifecycle assertions. Every test must release blocked workers and restore any process-global monkeypatches so teardown cannot leak threads or state into later tests.

Stress/soak testing, AnyIO worker instrumentation, Uvicorn multi-process behavior, and broad production executor redesign are separate concerns and should not be folded into these deterministic regressions.