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Kyle Carberry
1f37df4db3
## Summary Scale-tested the `chatd` package with mock-based benchmarks to identify performance bottlenecks. This PR fixes 6 of the 8 identified issues, ranked by severity. ## Changes ### 1. Parallel tool execution (HIGH) — `chatloop.go` `executeTools` ran tool calls sequentially. Now dispatches all calls concurrently via goroutines with `sync.WaitGroup`. Results are pre-allocated by index (no mutex needed). `onResult` callbacks fire as each tool completes. ### 2. Pubsub-backed subagent await (HIGH) — `subagent.go` `awaitSubagentCompletion` polled the DB every 200ms. Now subscribes to the child chat's `ChatStreamNotifyChannel` via pubsub for near-instant notifications. Fallback poll reduced to 5s. Falls back to 200ms only when `pubsub == nil` (single-instance / in-memory). ### 3. Per-chat stream locking (MEDIUM) — `chatd.go` Replaced single global `streamMu` + `map[uuid.UUID]*chatStreamState` with `sync.Map` where each `chatStreamState` has its own `sync.Mutex`. Zero cross-chat contention. ### 4. Batch chat acquisition (MEDIUM) — `chatd.go` `processOnce` acquired 1 chat per tick. Now loops up to `maxChatsPerAcquire = 10` per tick, avoiding idle time when many chats are pending. ### 5. Reduced heartbeat frequency (LOW-MEDIUM) — `chatd.go` `chatHeartbeatInterval` changed from 30s to 60s. Safe given the 5-minute `DefaultInFlightChatStaleAfter`. ### 6. O(depth) descendant check (LOW) — `subagent.go` Replaced top-down BFS (`O(total_descendants)` queries) with bottom-up parent-chain walk (`O(depth)` queries). Includes cycle protection. ## Not addressed (intentionally) - Message serialization overhead - Buffer eviction (`buffer[1:]` pattern)