test: unit tests for the sub agent spawning system

docs/testing/plans/11-sub-agent-spawning.md

@@ -10,49 +10,68 @@ to request user input through the parent.
 ## Behaviors to test
 
 ### Spawn
-- [ ] agent__spawn creates child agent in background
-- [ ] Child gets own RequestContext with incremented depth
-- [ ] Child gets own session, model, functions
-- [ ] Child gets shared root_escalation_queue
-- [ ] Child gets inbox for teammate messaging
-- [ ] Child MCP servers acquired if configured
-- [ ] Max concurrent agents enforced
-- [ ] Max depth enforced
-- [ ] Agent not found → error
-- [ ] can_spawn_agents=false → no spawn tools available
+- [ ] agent__spawn creates child agent in background (integration)
+- [ ] Child gets own RequestContext with incremented depth (integration)
+- [ ] Child gets own session, model, functions (integration)
+- [ ] Child gets shared root_escalation_queue (integration)
+- [ ] Child gets inbox for teammate messaging (integration)
+- [ ] Child MCP servers acquired if configured (integration)
+- [x] Max concurrent agents enforced (Supervisor.register)
+- [x] Max depth enforced (Supervisor.register)
+- [ ] Agent not found → error (integration)
+- [ ] can_spawn_agents=false → no spawn tools available (integration)
 
 ### Collect/Check
-- [ ] agent__check returns PENDING or result
-- [ ] agent__collect blocks until done, returns output
-- [ ] Output summarization when exceeds threshold
-- [ ] Summarization uses configured model
+- [ ] agent__check returns PENDING or result (integration)
+- [ ] agent__collect blocks until done, returns output (integration)
+- [ ] Output summarization when exceeds threshold (integration)
+- [ ] Summarization uses configured model (integration)
 
 ### Task queue
-- [ ] agent__task_create creates tasks with dependencies
-- [ ] agent__task_complete marks done, unblocks dependents
-- [ ] Auto-dispatch spawns agent for unblocked tasks
-- [ ] agent__task_list shows all tasks with status
+- [x] agent__task_create creates tasks with dependencies
+- [x] agent__task_complete marks done, unblocks dependents
+- [x] Auto-dispatch agent/prompt stored on task
+- [x] agent__task_list shows all tasks with status
 
 ### Escalation
-- [ ] Child calls user__ask → escalation created
-- [ ] Parent sees pending_escalations notification
-- [ ] agent__reply_escalation unblocks child
-- [ ] Escalation timeout → fallback message
+- [x] Escalation submitted and retrievable
+- [x] Pending summary contains correct fields
+- [x] Reply reaches receiver via oneshot channel
+- [ ] Escalation timeout → fallback message (integration)
 
 ### Teammate messaging
-- [ ] agent__send_message delivers to sibling inbox
-- [ ] agent__check_inbox drains messages
+- [x] Deliver to inbox
+- [x] Drain empties inbox
+- [x] Drain ordering: shutdown > task_completed > text
 
 ### Child agent lifecycle
-- [ ] run_child_agent loops: create input → call completions → process results
-- [ ] Child uses before/after_chat_completion
-- [ ] Child tool calls evaluated via eval_tool_calls
-- [ ] Child exits cleanly, supervisor cancels on completion
+- [ ] run_child_agent loops (integration)
+- [ ] Child uses before/after_chat_completion (integration)
+- [ ] Child tool calls evaluated (integration)
+- [ ] Child exits cleanly (integration)
 
 ## Context switching scenarios
-- [ ] Parent spawns child with MCP → child MCP works independently
-- [ ] Parent exits agent → all children cancelled
-- [ ] Multiple children share escalation queue correctly
+- [ ] Parent spawns child with MCP (integration)
+- [ ] Parent exits agent → all children cancelled (integration)
+- [ ] Multiple children share escalation queue correctly (integration)
+
+## Additional behaviors tested (not in original plan)
+
+- [x] EscalationQueue: default, submit, take, take_nonexistent, has_pending
+- [x] EscalationQueue: pending_summary with/without options, empty
+- [x] EscalationQueue: reply via oneshot channel
+- [x] new_escalation_id: prefix and uniqueness
+- [x] Inbox: new/default empty, deliver+drain, drain empties, multiple deliveries
+- [x] Inbox: clone preserves messages, clone is independent
+- [x] Supervisor: new defaults, register count, take removes, take nonexistent
+- [x] Supervisor: inbox accessor, list_agents, task_queue accessible
+- [x] Supervisor: register allows at max_depth boundary
+- [x] AgentExitStatus: equality/inequality
+- [x] TaskQueue: fail sets status, get missing returns None
+- [x] TaskQueue: dispatch_agent/prompt stored, claim blocked fails
+- [x] TaskQueue: list sorted by id, default empty
+- [x] TaskQueue: dependency on nonexistent errors, complete nonexistent
+- [x] TaskNode: is_runnable when pending+unblocked, not when blocked
 
 ## Old code reference
 - `src/function/supervisor.rs` — all handler functions