During SIGHUP testing with 6+ active sessions, ChromaSync.ensureConnection()
had no mutex — concurrent fire-and-forget syncObservation() calls each spawned
a chroma-mcp subprocess via StdioClientTransport, creating 641 orphans in ~5min.
Error-driven reconnection formed a positive feedback loop amplifying the storm.
Defense layers:
- Layer 0: Connection mutex via promise memoization (prevents concurrent spawns)
- Layer 1: Pre-spawn process count guard using execFileSync('ps') (kills excess)
- Layer 2: Hardened close() with try-finally + Unix pkill in GracefulShutdown
- Layer 3: Count-based orphan reaper in ProcessManager (not age-based)
- Layer 4: Circuit breaker stops retries after 3 consecutive failures for 60s
Closes#1063, closes#695
Relates to #1010, #707
Rod Boev
a3f9e7f638