---
name: review-race-conditions-open-f1c42f5c146c
description: Open Audit for race conditions in timers, hotkeys, callbacks, and shared state
user-invocable: true
disable-model-invocation: true
---
Enter planning mode. Systematically audit the codebase for race conditions. Use maximum parallelism — spawn explore agents for independent areas.

## AHK v2 Concurrency Model

AHK v2 is single-threaded but **not atomic** — timers, hotkeys, and callbacks CAN interrupt each other mid-execution. `Critical "On"` prevents interruption for the current thread. This is the only synchronization primitive available. See `.claude/rules/ahk-patterns.md` (Race Conditions section) and `.claude/rules/keyboard-hooks.md` for established patterns.

## What to Look For

## Known Safe Patterns (Do NOT Flag)

These have been deliberately designed and tested — flagging them wastes time:

- `Critical "On"` held through the entire `GUI_OnInterceptorEvent` handler including rendering (~16ms). This is intentional — releasing early causes corruption.
- `SendMode("Event")` instead of `SendInput` — prevents hook uninstall during sends.
- Async activation with `gGUI_EventBuffer` — events buffered while `gGUI_Pending.phase != ""`.
- Lost Tab synthesis (`ALT_DN` + `ALT_UP` without `TAB`).
- Flight recorder `FR_Record()` — pre-allocated ring buffer, writes are inherently safe.
- `_GUI_LogError()` — always-on by design.

## Validation

After explore agents report back, **validate every finding yourself**. Race conditions are easy to hypothesize and hard to confirm. Many "races" identified by exploration are actually guarded by Critical sections or by AHK's threading model (only one pseudo-thread runs at a time; interruption only happens at specific yield points).

For each candidate:

1. **Cite evidence**: "I verified by reading `file.ahk` lines X–Y" with actual code quoted. Vague line references are not sufficient.
2. **Trace the interrupt path**: Which specific callback could interrupt this code? Is it a timer, hotkey, or WinEvent? At what point in the vulnerable code would the interruption occur?
3. **Counter-argument**: "What would make this race impossible?" — Is there a Critical section in a caller? Does AHK's threading model prevent this specific interleaving? Is the state only accessed from one callback type?
4. **Observed vs inferred**: State whether you saw unguarded concurrent access directly, or inferred it from code structure. Inferred races need stronger evidence.
5. **Reproducibility**: Can this race actually manifest in normal usage, or only under extreme timing? A theoretical race in a once-per-session init path is lower priority than one in a per-keystroke hot path.

## Plan Format

Group by severity (data corruption > logic error > cosmetic):

| File | Lines | Race Description | Interrupt Source | Severity | Fix |
|------|-------|-----------------|-----------------|----------|-----|
| `file.ahk` | 42–58 | `gFoo` read-then-write without Critical | Timer `_HeartbeatTick` | Data corruption | Wrap in `Critical "On"` / `Critical "Off"` |

For each fix, note:
- Whether it introduces new Critical section duration that could affect input latency
- Whether the fix is localized or requires coordinating changes across files

Ignore any existing plans — create a fresh one.


---
Source attribution: cwilliams5
Original project: https://github.com/cwilliams5/Alt-Tabby/blob/6e941fe6d8344facc4f24c373f41999ff6da4c04/.claude/skills/review-race-conditions-open/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2025 Cody Williams

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Dave AI resource metadata

Creator / publisher: cwilliams5
Original project: https://github.com/cwilliams5/Alt-Tabby/blob/6e941fe6d8344facc4f24c373f41999ff6da4c04/.claude/skills/review-race-conditions-open/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering
Roles: Backend Developer, DevOps / SRE, QA / Test Engineer
Specialties: Backend, Testing
Tools: Ahk
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 06984809bafd27e5c21bb6763708f4190061130b364d1761ec0a350c8619b5d5