# Complexity Audit Report

**Branch**: fix/issue-28-graph-corruption-shallow-copy
**Base**: main
**Date**: 2025-11-28 11:04

---

## Executive Summary

This branch addresses a critical security bug (Issue #28) where shallow copy in `wouldCreateCycle()` corrupted the dependency graph. The fix is correct and well-implemented. Additional changes include settling workers tracking for spawn burst protection and configuration validation logging.

**Complexity Score**: 8/10 (Good - Low complexity with appropriate safeguards)

**Issue Counts**:
- BLOCKING: 0
- SHOULD FIX: 2
- INFORMATIONAL: 3

---

## Changed Files Analysis

| File | Lines Changed | Category |
|------|---------------|----------|
| src/core/dependency-graph.ts | +7 | Core fix |
| src/implementations/resource-monitor.ts | +67 | Performance feature |
| src/core/configuration.ts | +10 | Logging enhancement |
| src/services/handlers/worker-handler.ts | +6 | Type fix + integration |
| src/core/interfaces.ts | +6 | Interface extension |
| tests/unit/core/dependency-graph.test.ts | +92 | Regression tests |
| tests/unit/implementations/system-resource-monitor.test.ts | +89 | Feature tests |

---

## BLOCKING Issues in Your Changes

**None identified.**

The core fix is correctly implemented:

```typescript
// BEFORE (shallow copy - corrupted graph):
const tempGraph = new Map(this.graph);

// AFTER (deep copy - correct):
const tempGraph = new Map(
  Array.from(this.graph.entries()).map(([k, v]) => [k, new Set(v)])
);
```

This is the idiomatic pattern for deep-copying a `Map<string, Set<string>>` in JavaScript.

---

## SHOULD FIX Issues in Code You Touched

### 1. [MEDIUM] Magic number for settling window (resource-monitor.ts:30)

**File**: `/workspace/delegate/src/implementations/resource-monitor.ts`
**Lines**: 30-31

```typescript
private readonly SETTLING_WINDOW_MS = 15000; // 15 seconds for worker to "settle"
private recentSpawnTimestamps: number[] = [];
```

**Issue**: The 15-second settling window is hardcoded. While documented with a comment, this value should ideally be configurable or at least derived from a configuration constant.

**Recommendation**: Consider adding `settlingWindowMs` to the Configuration schema, or at minimum define the constant in terms of existing config values:

```typescript
// Option A: Make configurable
private readonly SETTLING_WINDOW_MS: number;
constructor(config: Configuration) {
  this.SETTLING_WINDOW_MS = config.workerSettlingWindowMs ?? 15000;
}

// Option B: Document relationship to other timings
// SETTLING_WINDOW_MS should be >= 3 * resourceMonitorIntervalMs
private readonly SETTLING_WINDOW_MS = 15000;
```

**Severity**: MEDIUM - Not blocking, but reduces configurability.

---

### 2. [MEDIUM] Mutable array for timestamp tracking (resource-monitor.ts:31)

**File**: `/workspace/delegate/src/implementations/resource-monitor.ts`
**Lines**: 31, 82-84, 176

```typescript
private recentSpawnTimestamps: number[] = [];

// Mutation in canSpawnWorker():
this.recentSpawnTimestamps = this.recentSpawnTimestamps.filter(
  t => now - t < this.SETTLING_WINDOW_MS
);

// Mutation in recordSpawn():
this.recentSpawnTimestamps.push(Date.now());
```

**Issue**: The mutable array pattern works but could lead to subtle issues:
1. No cleanup mechanism if `recordSpawn()` is called but `canSpawnWorker()` is never called
2. Array grows unbounded if cleanup only happens during spawn checks
3. No synchronization for concurrent access (though Node.js is single-threaded for JS)

**Recommendation**: Consider using a more robust data structure:

```typescript
// Bounded circular buffer or explicit cleanup
private cleanupSettlingWorkers(): void {
  const now = Date.now();
  this.recentSpawnTimestamps = this.recentSpawnTimestamps.filter(
    t => now - t < this.SETTLING_WINDOW_MS
  );
}

// Call from recordSpawn() as well
recordSpawn(): void {
  this.cleanupSettlingWorkers(); // Prevent unbounded growth
  this.recentSpawnTimestamps.push(Date.now());
  // ...
}
```

**Severity**: MEDIUM - Edge case but worth hardening.

---

## INFORMATIONAL Pre-existing Issues (Not Blocking)

### 1. [LOW] Double counting potential in settling workers

**File**: `/workspace/delegate/src/implementations/resource-monitor.ts`
**Lines**: 86-88, 293-296

```typescript
// In canSpawnWorker():
const effectiveWorkerCount = this.workerCount + settlingWorkers;

// In worker-handler.ts (caller):
this.resourceMonitor.incrementWorkerCount();
this.resourceMonitor.recordSpawn?.();
```

**Observation**: When `incrementWorkerCount()` and `recordSpawn()` are called together, there is a brief window where the worker is counted twice (once in `workerCount`, once in settling). This is intentional (settling workers account for metrics lag), but the comment at line 88 could be clearer about this design decision.

**Status**: Correct behavior, comment could be improved.

---

### 2. [LOW] Optional chaining for recordSpawn() call

**File**: `/workspace/delegate/src/services/handlers/worker-handler.ts`
**Lines**: 295-296

```typescript
// Record spawn for settling worker tracking (accounts for lag in load average)
this.resourceMonitor.recordSpawn?.();
```

**Observation**: The optional chaining (`?.`) handles the case where `recordSpawn` might not exist on the interface. This is correct because `recordSpawn` is defined as optional in the interface (`recordSpawn?(): void`).

**Status**: Correct pattern for optional interface methods.

---

### 3. [LOW] Configuration validation console.warn

**File**: `/workspace/delegate/src/core/configuration.ts`
**Lines**: 134-141

```typescript
console.warn(
  `[Delegate] Configuration validation failed, using defaults:\n${errors}`
);
```

**Observation**: Using `console.warn` directly rather than going through the Logger interface. This is acceptable because:
1. Configuration loads before Logger is initialized
2. This is a startup-time warning, not runtime logging

**Status**: Acceptable trade-off for bootstrap timing.

---

## Cyclomatic Complexity Analysis

### wouldCreateCycle() - Lines 240-282

**Cyclomatic Complexity**: 4 (acceptable)
- 1 base path
- +1 for self-dependency check (line 245)
- +1 for node existence check (line 258)
- +1 for target node existence check (line 264)

**Assessment**: Well-structured with clear control flow.

---

### canSpawnWorker() - Lines 79-169

**Cyclomatic Complexity**: 7 (acceptable, approaching limit)
- 1 base path
- +1 for max workers check (line 89)
- +1 for resources error check (line 101)
- +1 for CPU cores check (line 118)
- +1 for memory check (line 134)
- +1 for load average check (line 148)
- +1 for early returns

**Assessment**: Method is longer (90 lines) but each check is straightforward. Consider extracting resource projection calculations into helper methods for improved readability:

```typescript
// Potential refactor (not blocking):
private projectResourceUsage(settlingWorkers: number): ProjectedResources {
  return {
    coresUsed: settlingWorkers * this.CORES_PER_WORKER,
    memoryUsed: settlingWorkers * this.MEMORY_PER_WORKER_MB * 1024 * 1024
  };
}
```

---

### loadConfiguration() - Lines 95-145

**Cyclomatic Complexity**: 3 (good)
- 1 base path
- +1 for each env var conditional (but these are flat, not nested)
- +1 for parse success check (line 131)

**Assessment**: Linear control flow, no deep nesting.

---

## Test Coverage Assessment

### Regression Tests Added (dependency-graph.test.ts)

| Test | Purpose | Coverage |
|------|---------|----------|
| `should not mutate graph when checking for cycles with existing task` | Primary regression test for Issue #28 | Critical path |
| `should not mutate graph when checking non-cycle with existing task` | Edge case: no cycle detected | Secondary path |
| `should not mutate graph with multiple cycle checks` | Accumulation test | Stress testing |

**Assessment**: Excellent regression test coverage. Tests verify the exact bug scenario.

---

### Feature Tests Added (system-resource-monitor.test.ts)

| Test | Purpose | Coverage |
|------|---------|----------|
| `should record spawn events` | Basic functionality | Smoke test |
| `should include settling workers in effective worker count` | Core feature | Happy path |
| `should expire settling workers after 15 second window` | Window expiration | Boundary |
| `should not expire settling workers within the window` | Window active | Boundary |
| `should correctly project resource usage for settling workers` | Resource projection | Integration |

**Assessment**: Good coverage of settling worker feature.

---

## Summary

### Your Changes:

| Severity | Count | Details |
|----------|-------|---------|
| CRITICAL | 0 | - |
| HIGH | 0 | - |
| MEDIUM | 2 | Magic number, mutable array pattern |
| LOW | 0 | - |

### Code You Touched:

| Severity | Count | Details |
|----------|-------|---------|
| HIGH | 0 | - |
| MEDIUM | 0 | - |
| LOW | 3 | Double counting note, optional chaining, console.warn |

### Pre-existing:

| Severity | Count | Details |
|----------|-------|---------|
| MEDIUM | 0 | - |
| LOW | 0 | - |

---

## Merge Recommendation

**APPROVED**

The core fix for Issue #28 is correct and well-tested. The settling workers feature is a reasonable performance improvement. The two MEDIUM issues identified are:

1. **Magic number**: Not critical - the value is documented and reasonable
2. **Mutable array**: Edge case only - bounded by settling window cleanup

Neither issue blocks merge. Both could be addressed in a future refactoring PR.

### Checklist:

- [x] Core bug fix is correct (deep copy pattern)
- [x] Regression tests cover the bug scenario
- [x] Feature tests cover new functionality
- [x] No increase in cyclomatic complexity beyond acceptable limits
- [x] Type safety improved (any -> Worker)
- [x] Security logging added for config validation

---

## Appendix: Files Modified

```
src/core/dependency-graph.ts          # Deep copy fix (Issue #28)
src/implementations/resource-monitor.ts  # Settling workers tracking
src/core/configuration.ts             # Validation logging
src/services/handlers/worker-handler.ts  # Type fix + recordSpawn integration
src/core/interfaces.ts                # recordSpawn optional method
tests/unit/core/dependency-graph.test.ts      # Regression tests
tests/unit/implementations/system-resource-monitor.test.ts  # Feature tests
CHANGELOG.md                          # Documentation
docs/TASK-DEPENDENCIES.md             # Line number fix
docs/architecture/TASK_ARCHITECTURE.md  # Deep copy pattern docs
package-lock.json                     # Dependency updates
```
