cwilliams5/review-race-conditions-open

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.