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story-kit: create 132_story_fix_toctou_race_in_agent_check_and_insert

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Dave
2026-02-24 12:02:01 +00:00
parent 00e5fc2ccc
commit 785f4900ab
1 changed files with 4 additions and 4 deletions
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.story_kit/work/1_upcoming/132_story_fix_toctou_race_in_agent_check_and_insert.md
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@@ -10,14 +10,14 @@ As a user running multiple agents, I want the agent pool to correctly enforce si
## Acceptance Criteria ## Acceptance Criteria
- [ ] The lock in start_agent (agents.rs ~lines 262-324) is held continuously from the availability check through the HashMap insert — no lock release between check and insert - [ ] The lock in start_agent (server/src/agents.rs ~lines 262-324) is held continuously from the availability check through the HashMap insert — no lock release between check and insert
- [ ] The lock in auto_assign_available_work (agents.rs ~lines 1196-1228) is held from find_free_agent_for_stage through the start_agent call, preventing a concurrent auto_assign from selecting the same agent - [ ] The lock in auto_assign_available_work (server/src/agents.rs ~lines 1196-1228) is held from find_free_agent_for_stage through the start_agent call, preventing a concurrent auto_assign from selecting the same agent
- [ ] A test demonstrates that concurrent start_agent calls for the same agent name on different stories result in exactly one running agent and one rejection - [ ] A test demonstrates that concurrent start_agent calls for the same agent name on different stories result in exactly one running agent and one rejection
- [ ] A test demonstrates that concurrent auto_assign_available_work calls do not produce duplicate assignments - [ ] A test demonstrates that concurrent auto_assign_available_work calls do not produce duplicate assignments
## Analysis ## Analysis
### Race 1: start_agent check-then-insert (agents.rs) ### Race 1: start_agent check-then-insert (server/src/agents.rs)
The single-instance check at ~lines 262-296 acquires the mutex, checks for duplicate agents, then **releases the lock**. The HashMap insert happens later at ~line 324 after **re-acquiring the lock**. Between release and reacquire, a concurrent call can pass the same check: The single-instance check at ~lines 262-296 acquires the mutex, checks for duplicate agents, then **releases the lock**. The HashMap insert happens later at ~line 324 after **re-acquiring the lock**. Between release and reacquire, a concurrent call can pass the same check:
@@ -32,7 +32,7 @@ The composite key at ~line 27 is `format!("{story_id}:{agent_name}")`, so `86:co
**Fix**: Hold the lock from the check (~line 264) through the insert (~line 324). This means the worktree setup and process spawn (~lines 297-322) must either happen inside the lock (blocking other callers) or the entry must be inserted as `Pending` before releasing the lock, with the process spawn happening after. **Fix**: Hold the lock from the check (~line 264) through the insert (~line 324). This means the worktree setup and process spawn (~lines 297-322) must either happen inside the lock (blocking other callers) or the entry must be inserted as `Pending` before releasing the lock, with the process spawn happening after.
### Race 2: auto_assign_available_work (agents.rs) ### Race 2: auto_assign_available_work (server/src/agents.rs)
At ~lines 1196-1215, the function locks the mutex, calls `find_free_agent_for_stage` to pick an available agent name, then **releases the lock**. It then calls `start_agent` at ~line 1228, which re-acquires the lock. Two concurrent `auto_assign` calls can both select the same free agent for different stories (or the same story) in this window. At ~lines 1196-1215, the function locks the mutex, calls `find_free_agent_for_stage` to pick an available agent name, then **releases the lock**. It then calls `start_agent` at ~line 1228, which re-acquires the lock. Two concurrent `auto_assign` calls can both select the same free agent for different stories (or the same story) in this window.