# Performance Audit Report

**Branch**: fix/timing-based-test-waits
**Base**: main
**Date**: 2025-12-28 22:51:00
**Files Analyzed**: 12
**Lines Changed**: +250 / -143

---

## Summary

This branch replaces timing-based test waits (`setTimeout`) with event-driven synchronization patterns (`flushEventLoop()`, `waitFor()`). The changes are primarily in test code with one minor production code enhancement.

**Key Improvement**: Tests no longer waste time on arbitrary delays (50-200ms per wait). The new `flushEventLoop()` uses `setImmediate` which executes in <1ms.

---

## [RED] Performance Issues in Your Changes (BLOCKING if Severe)

### NONE

No critical performance issues were introduced in production code. The production code change is a clean dependency injection enhancement following existing patterns.

---

## [YELLOW] Performance Issues in Code You Touched (Should Optimize)

### MEDIUM

**Handler Not Cleaned on Timeout** - `/workspace/delegate/tests/fixtures/test-doubles.ts:218-232` (line ADDED in this branch)

- **Problem**: The `waitFor()` method subscribes a handler that is never unsubscribed if the timeout fires
- **Impact**: Handler remains in memory and could fire on late events, causing test flakiness
- **Code**:
  ```typescript
  async waitFor<T = any>(
    eventType: string,
    options: { timeout?: number; filter?: (payload: T) => boolean } = {}
  ): Promise<T> {
    // ...
    return new Promise((resolve, reject) => {
      const timer = setTimeout(() => {
        reject(new Error(`Timeout waiting for '${eventType}' after ${timeout}ms`));
        // BUG: Handler is NOT unsubscribed here
      }, timeout);

      const handler = async (event: any) => {
        if (filter(event)) {
          clearTimeout(timer);
          resolve(event);
          // Handler remains subscribed after resolving
        }
      };

      this.subscribe(eventType, handler);
    });
  }
  ```
- **Fix**: Store handler reference and unsubscribe in both timeout and success paths
  ```typescript
  return new Promise((resolve, reject) => {
    let handler: any;
    const timer = setTimeout(() => {
      this.handlers.get(eventType)?.delete(handler);
      reject(new Error(`Timeout waiting for '${eventType}' after ${timeout}ms`));
    }, timeout);

    handler = async (event: any) => {
      if (filter(event)) {
        clearTimeout(timer);
        this.handlers.get(eventType)?.delete(handler);
        resolve(event);
      }
    };

    this.subscribe(eventType, handler);
  });
  ```
- **Severity**: MEDIUM (test code only, does not affect production)
- **Recommendation**: Fix for test reliability, not blocking for merge

---

### LOW

**Once Handler Wrapper Not Tracked** - `/workspace/delegate/tests/fixtures/test-doubles.ts:250-258` (line ADDED in this branch)

- **Problem**: The `once()` method wraps the original handler but does not track the wrapper for removal
- **Impact**: If `removeListener()` is called with the original handler, it will not match the wrapper
- **Code**:
  ```typescript
  once(eventType: string, handler: (data: any) => void): void {
    let called = false;
    const wrappedHandler = async (event: any) => {
      if (!called) {
        called = true;
        handler(event);
      }
    };
    this.subscribe(eventType, wrappedHandler);
    // BUG: wrappedHandler is subscribed, but handler is what would be passed to removeListener
  }
  ```
- **Severity**: LOW (test code only, dispose() handles full cleanup)
- **Recommendation**: Consider adding wrapper-to-original mapping if removeListener compatibility is needed

---

## [INFO] Pre-existing Performance Issues (Not Blocking)

### NONE

No pre-existing performance issues were identified in the files reviewed.

---

## Performance Improvements Introduced

This branch introduces **significant performance improvements** to the test suite:

| Original Pattern | New Pattern | Improvement |
|------------------|-------------|-------------|
| `setTimeout(resolve, 50)` | `flushEventLoop()` | ~50ms saved per call |
| `setTimeout(resolve, 100)` | `flushEventLoop()` | ~100ms saved per call |
| `setTimeout(resolve, 150)` | `flushEventLoop()` | ~150ms saved per call |
| `setTimeout(resolve, 200)` | `flushEventLoop()` | ~200ms saved per call |

**Estimated Test Suite Speedup**:
- Counted ~60 timing-based waits replaced
- Average wait: ~100ms
- **Total time saved**: ~6 seconds per test run

**Additional Benefits**:
1. **Deterministic tests**: Event-driven sync eliminates timing-related flakiness
2. **Faster feedback**: Developers get test results faster
3. **CI cost reduction**: Less compute time per PR

---

## Production Code Analysis

### `/workspace/delegate/src/bootstrap.ts`

**Change**: Added `resourceMonitor` option to `BootstrapOptions` interface and injection logic.

```typescript
export interface BootstrapOptions {
  processSpawner?: ProcessSpawner;
  resourceMonitor?: ResourceMonitor;  // NEW
  skipResourceMonitoring?: boolean;
}
```

**Analysis**:
- Follows existing pattern for `processSpawner`
- Clean dependency injection
- No runtime overhead (conditional check only during bootstrap)
- Enables `TestResourceMonitor` injection for tests

**Verdict**: APPROVED - No performance concerns

---

## Summary

**Your Changes:**
- [RED] CRITICAL: 0
- [RED] HIGH: 0
- [RED] MEDIUM: 0

**Code You Touched (Test Code):**
- [YELLOW] MEDIUM: 1 (handler cleanup in waitFor)
- [YELLOW] LOW: 1 (once wrapper tracking)

**Pre-existing:**
- [INFO] NONE

**Performance Score**: 9/10

**Merge Recommendation**: APPROVED

The branch introduces significant test performance improvements by replacing arbitrary timing delays with event-driven synchronization. The minor issues identified are in test utility code only and do not affect production. The production code change is clean and follows established patterns.

---

## Optimization Priority

**Optional improvements (non-blocking):**
1. Add handler cleanup in `TestEventBus.waitFor()` timeout path
2. Consider wrapper tracking in `TestEventBus.once()` if removeListener compatibility needed

**No action required before merge.**

---

## PR Comments

Created: 1
Skipped: 1

**Comments Created:**
1. `tests/fixtures/test-doubles.ts:232` - Handler cleanup in waitFor() (MEDIUM)

**Comments Skipped:**
1. `tests/fixtures/test-doubles.ts:258` - once() wrapper tracking (LOW) - Too minor for PR comment

**Rationale**: Created comment for MEDIUM severity issue with actionable fix. Skipped LOW severity issue as it does not affect test reliability in practice.

