# Review Race Conditions Open

> Open Audit for race conditions in timers, hotkeys, callbacks, and shared state

- Skill: `majiayu000/review-race-conditions-open` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/review-race-conditions-open`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/review-race-conditions-open/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/review-race-conditions-open

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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.