Contributions to large open-source systems. More as they land.
MongoDB — multiPlannerFallbackEngaged
When a pinned index can't be used, MongoDB's planner falls back to multi-planning and races a plan against every index. That extra planning cost is invisible to operators, so this adds a flag for it to the slow query log and profiler. The subtle part is where the flag lives: the obvious home beside fromMultiPlanner in AdditiveMetrics is replaced mid-operation after execution, so a flag set during planning would be silently overwritten. Shipped in MongoDB 9.0 (SERVER-84018).
Bitcoin Core — bitcoind ZMQ startup
bitcoind starts even when a configured ZMQ socket fails to bind, logging it only at debug level, so tools like LND lose block notifications days later in someone else's process. The silent behavior traced back to a leftover from a 2019 crash fix. The change splits one overloaded function so a real bind error can't be confused with "ZMQ not configured". Revived from an abandoned PR; Concept ACK, in review.