Harden Mimir subprocess lifecycle (deadlock, restart, timeout, key collisions)#6
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- stderr=DEVNULL (was PIPE, never drained): prevents pipe-buffer deadlock that silently hung the plugin on long sessions - reader thread + queue with deadline: _mcp_send now times out (RECALL_MCP_TIMEOUT, default 30s) instead of blocking forever - lazy single restart when mimir died; clean "Memory backend unavailable" JSON-RPC error instead of leaked AttributeError - content-hash suffix on auto-generated keys: distinct facts with a shared 50-char prefix no longer silently overwrite each other - guarded shutdown wait (TimeoutExpired -> kill) - tests: 15 unit tests over the protocol seam + lifecycle machinery - CI: GitHub Actions pytest workflow Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This was referenced Jun 12, 2026
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Fixes the four subprocess lifecycle failure modes from the 2026-06-12 deep-dive review (A-1 through A-5).
Fixes
stderr=PIPEthat nothing drained; once the OS pipe buffer filled, Mimir blocked on its next stderr write and the plugin hung forever. Nowstderr=DEVNULL._mimir_proc = Noneand every invoke leakedAttributeError: 'NoneType' object has no attribute 'stdin'; a mid-session death raised forever with no restart. Now_mcp_sendlazily restarts Mimir once, and if that fails the agent gets a clean JSON-RPC error:Memory backend unavailable — …._mcp_sendblocked indefinitely onreadline(). A reader thread now feeds a queue, and reads enforce a deadline (RECALL_MCP_TIMEOUT, default 30s) — a stuck call raises instead of freezing every memory tool.handle()), key generation, timeout/restart machinery, and the reader thread — no Mimir binary required. GitHub Actions workflow added.Verification
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