feat(session): optimistic locking for concurrent refinement races - #122
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…t races - Add RefinementInProgressError exception class - Add REFINE_LOCK_TTL_MS = 120_000 (2 min TTL covers worst-case pipeline) - Add acquire_lock() and release_lock() to RedisSessionStore using SET NX PX - Acquire lock in refine() after all validation guards, before state mutation - Release lock in _run_refinement() finally block — always runs on success and failure - Add 409 catch for RefinementInProgressError in POST /refine route handler - 4 new tests (Section 11): lock conflict, release after success, release after failure, 409 route response — 46 total passing, mypy clean Closes #103
CodeNinjaSarthak
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May 5, 2026
…t races (#122) - Add RefinementInProgressError exception class - Add REFINE_LOCK_TTL_MS = 120_000 (2 min TTL covers worst-case pipeline) - Add acquire_lock() and release_lock() to RedisSessionStore using SET NX PX - Acquire lock in refine() after all validation guards, before state mutation - Release lock in _run_refinement() finally block — always runs on success and failure - Add 409 catch for RefinementInProgressError in POST /refine route handler - 4 new tests (Section 11): lock conflict, release after success, release after failure, 409 route response — 46 total passing, mypy clean Closes #103
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Changes
RefinementInProgressError— new exception, maps to 409 at route layerRedisSessionStore.acquire_lock()—SET NX PXprimitive, returns boolRedisSessionStore.release_lock()—DELprimitiverefine()after all validation guards, before state mutation_run_refinement()finallyblock — guaranteed on success and failureREFINE_LOCK_TTL_MS = 120_000— 2 min TTL as safety net if process dies mid-runFailure mode
Second concurrent POST /refine → 409 Conflict immediately, no state mutation, no phantom pipeline run.
Tests
46 passing, mypy clean. 4 new tests:
Closes #103