Changed newTestAgentLoop calls from using 3 blank identifiers to 2 by
assigning the unused provider parameter and explicitly marking it as
unused with `_ = provider`. This fixes the dogsled linter violations
that were causing CI failures.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Add nil checks in NewSpawnTool and NewSubagentTool constructors to
handle nil manager gracefully. Fix spelling errors (cancelled->canceled)
and remove unused test code. Update tests to use mock spawner.
Replace hardcoded constants with config-driven parameters in agents.defaults:
- MaxDepth, MaxConcurrent, DefaultTimeout, DefaultTokenBudget, ConcurrencyTimeout
- Support JSON config and env vars (PICOCLAW_AGENTS_DEFAULTS_SUBTURN_*)
- Add getSubTurnConfig() for runtime config resolution with defaults
- Apply defaultTokenBudget when no explicit budget is provided
Rationale: SubTurn is agent execution infrastructure, not a tool, so it belongs
in agents.defaults rather than tools config.
Example:
{
"agents": {
"defaults": {
"subturn": {
"max_depth": 5,
"max_concurrent": 10,
"default_timeout_minutes": 10
}
}
}
}
- Critical flag was declared but never acted on; non-critical SubTurns
now break out of the iteration loop when IsParentEnded() returns true
- tools.SubTurnConfig was missing Critical/Timeout/MaxContextRunes,
making those fields unreachable from the tools layer; added fields and
wired them through AgentLoopSpawner.SpawnSubTurn
- Removed subTurnResults sync.Map from AgentLoop — it was a redundant
alias for the same channel already stored in turnState.pendingResults;
dequeuePendingSubTurnResults now reads directly via activeTurnStates
- Replace hardcoded concurrencySem size 5 with maxConcurrentSubTurns constant
- Update affected tests to match new dequeuePendingSubTurnResults API
This commit addresses several critical concurrency and state management bugs within the SubTurn execution and delivery logic.
1. Fix Goroutine Leak & Deadlock in deliverSubTurnResult:
- Replaced non-blocking select with a safe blocking select that listens to `resultChan` and a new `<-parentTS.Finished()` channel.
- This ensures results are not arbitrarily dropped when the channel is full (preventing orphaned valid results), while also guaranteeing the child goroutine safely unblocks and exits if the parent finishes execution early.
2. Prevent "Send on Closed Channel" Fatal Panics:
- Removed `close(pendingResults)` and `drainPendingResults` from `turnState.Finish()`.
- The pendingResults channel is now naturally garbage collected, completely eliminating the race condition panic when a child attempts delivery at the exact moment the parent finishes.
- Added a `defer recover()` failsafe inside deliverSubTurnResult to gracefully emit Orphan events in extreme edge cases.
3. Fix Truncation Recovery Prompt Drop:
- Fixed the runTurn truncation retry logic by introducing an explicit `promptAlreadyAdded` boolean.
- Ensures that the dynamically generated `recoveryPrompt` is correctly injected into the LLM history sequence on subsequent iterations, adhering to API roles without duplicating arrays.
4. Test Suite Stabilization:
- Fixed TestDeliverSubTurnResultNoDeadlock to accurately wait for deterministic deliveries instead of racing timeouts.
- Replaced defunct closed-channel tests with TestFinishedChannelClosedState matching the new Finished() mechanism.
- Fixed the Finish(true) parameter in TestGrandchildAbort_CascadingCancellation to correctly validate Context cascade behavior.
- All tests now pass cleanly without hanging or emitting false positives.
Problem:
When parent turn finishes early, all child SubTurns receive "context canceled"
error,because child context was derived from parent context.
Solution:
Implement a lifecycle management system that distinguishes between:
- Graceful finish (Finish(false)): signals parentEnded, children continue
- Hard abort (Finish(true)): immediately cancels all children
Changes:
- turn_state.go:
- Add parentEnded atomic.Bool to signal parent completion
- Add parentTurnState reference for IsParentEnded() checks
- Modify Finish(isHardAbort bool) to distinguish abort types
- subturn.go:
- Add Critical bool to SubTurnConfig (Critical SubTurns continue after parent ends)
- Add Timeout time.Duration for SubTurn self-protection
- Use independent context (context.Background()) instead of derived context
- SubTurns check IsParentEnded() to decide whether to continue or exit
- loop.go:
- Call Finish(false) for normal completion (graceful)
- Add IsParentEnded() check in LLM iteration loop
- steering.go:
- HardAbort calls Finish(true) to immediately cancel children
Behavior:
- Normal finish: parentEnded=true, children continue, orphan results delivered
- Hard abort: all children cancelled immediately via context
- Critical SubTurns: continue running after parent finishes gracefully
- Non-Critical SubTurns: can exit gracefully when IsParentEnded() returns true
- Fix synchronous SubTurn calls placing results in pendingResults channel,
causing double delivery. Now only async calls (Async=true) use the channel.
- Move deliverSubTurnResult into defer to ensure result delivery even when
runTurn panics. Add TestSpawnSubTurn_PanicRecovery to verify.
- Fix ContextWindow incorrectly set to MaxTokens; now inherits from
parentAgent.ContextWindow.
- Add TestSpawnSubTurn_ResultDeliverySync to verify sync behavior.
Critical fixes (5):
- Fix turnState hierarchy corruption in nested SubTurns by checking context
before creating new root turnState in runAgentLoop
- Fix deadlock risk in deliverSubTurnResult by separating lock and channel ops
- Fix session rollback race in HardAbort by calling Finish() before rollback
- Fix resource leak by closing pendingResults channel in Finish() with recovery
- Add thread-safety docs for childTurnIDs and isFinished fields
Medium priority fixes (5):
- Move globalTurnCounter to AgentLoop.subTurnCounter to prevent ID conflicts
- Improve semaphore acquisition to ensure release even on early validation failures
- Document design choice: ephemeral sessions start empty for complete isolation
- Add final poll before Finish() to capture late-arriving SubTurn results
- Remove duplicate channel registration in spawnSubTurn to fix timing issues
Testing:
- Add 6 new tests covering hierarchy, deadlock, ordering, channel lifecycle,
final poll, and semaphore behavior
- All 12 SubTurn tests passing with race detector
This resolves 10 critical and medium issues (5 race conditions, 2 resource leaks,
3 timing issues) identified in code review, bringing SubTurn to production-ready state.
- Fix turnState hierarchy corruption when SubTurns recursively call runAgentLoop
by checking context for existing turnState before creating new root
- Fix deadlock risk in deliverSubTurnResult by separating lock and channel operations
- Fix session rollback race in HardAbort by calling Finish() before rollback
- Fix resource leak by closing pendingResults channel in Finish() with panic recovery
- Add thread-safety documentation for childTurnIDs and isFinished fields
- Move globalTurnCounter to AgentLoop.subTurnCounter to prevent ID conflicts
- Improve semaphore acquisition to ensure release even on early validation failures
- Document design choice: ephemeral sessions start empty for complete isolation
- Add 5 new tests: hierarchy, deadlock, order, channel close, and semaphore
- Add initialHistoryLength field to turnState to snapshot session state at turn start
- Save initial history length in runAgentLoop when creating root turnState
- Implement session rollback in HardAbort via SetHistory, truncating to initial length
- Add TestHardAbortSessionRollback to verify history rollback after abort
- Import providers package in subturn_test.go for Message type
This ensures that when a user triggers hard abort, all messages added during
the aborted turn are discarded, restoring the session to its pre-turn state.
- Add maxConcurrentSubTurns constant (5) and concurrencySem channel to turnState
- Acquire/release semaphore in spawnSubTurn to limit concurrent child turns per parent
- Add activeTurnStates sync.Map to AgentLoop for tracking root turn states by session
- Implement HardAbort(sessionKey) method to trigger cascading cancellation via turnState.Finish()
- Register/unregister root turnState in runAgentLoop for hard abort lookup
- Add TestSubTurnConcurrencySemaphore to verify semaphore capacity enforcement
- Add TestHardAbortCascading to verify context cancellation propagates to child turns
- Add subTurnResults sync.Map to AgentLoop for per-session channel tracking
- Add register/unregister/dequeue methods in steering.go
- Poll SubTurn results in runLLMIteration at loop start and after each tool,
injecting results as [SubTurn Result] messages into parent conversation
- Initialize root turnState in runAgentLoop, propagate via context
(withTurnState/turnStateFromContext), call rootTS.Finish() on completion
- Wire Spawn Tool to spawnSubTurn via SetSpawner in registerSharedTools,
recovering parentTS from context for proper turn hierarchy
- Refactor subagent.go to use SetSpawner pattern
- Add TestSubTurnResultChannelRegistration and TestDequeuePendingSubTurnResults
- Replace duplicate types (ToolResult/Session/Message) with real project types
- Implement ephemeralSessionStore satisfying session.SessionStore interface
- Connect runTurn to real AgentLoop via runAgentLoop + AgentInstance
- Fix subturn_test.go to match updated signatures and types
Co-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>
lxowalle