# Documentation Audit Report

**Branch**: refactor/decompose-large-handlers  
**Base**: main  
**Date**: 2025-12-06 22:00  
**Auditor**: Automated Documentation Audit

---

## Executive Summary

This branch introduces significant refactoring to decompose large handler methods (`processNextTask()` and `handleTaskDelegated()`) into smaller, well-documented helper methods. The branch also adds a critical spawn serialization mutex to fix a TOCTOU race condition.

**Changes Analyzed**:
- `src/services/handlers/worker-handler.ts` - processNextTask() decomposition + spawn lock
- `src/services/handlers/dependency-handler.ts` - handleTaskDelegated() decomposition
- `docs/architecture/HANDLER-DECOMPOSITION-INVARIANTS.md` - New architecture documentation
- `tests/unit/services/handlers/worker-handler.test.ts` - New characterization tests
- `tests/unit/services/handlers/dependency-handler.test.ts` - New characterization tests
- `tests/fixtures/test-doubles.ts` - Test double enhancements

---

## Issues in Your Changes (BLOCKING)

### HIGH-1: Outdated Line References in Architecture Doc

**File**: `/workspace/delegate/docs/architecture/HANDLER-DECOMPOSITION-INVARIANTS.md`  
**Lines**: 21, 93  
**Severity**: HIGH

The new architecture document references specific line numbers that may be inaccurate after decomposition:

```markdown
Location: `src/services/handlers/worker-handler.ts:377-434`
...
Location: `src/services/handlers/dependency-handler.ts:138-282`
```

**Problem**: Line references become stale as code changes. This document was created with the decomposition in mind, but the exact line numbers (377-434 for processNextTask) should be verified. After decomposition, the main orchestration method now starts at line 377 but the actual extracted methods span lines 255-362.

**Fix**: Either:
1. Update to accurate line ranges after decomposition
2. Remove line numbers entirely and reference method names only

---

### MEDIUM-1: Missing @returns JSDoc for validateSingleDependency()

**File**: `/workspace/delegate/src/services/handlers/dependency-handler.ts`  
**Lines**: 137-180  
**Severity**: MEDIUM

The method has a comment explaining the return structure, but lacks formal JSDoc @returns tag with type information:

```typescript
/**
 * Validate a single dependency - check for cycles and depth limits
 * PURE: Read-only operation, no side effects
 *
 * @returns Validation result with type indicating: ok, cycle, depth, or system error
 */
private validateSingleDependency(
  taskId: TaskId,
  depId: TaskId
): { depId: TaskId; error: Error | null; type: 'ok' | 'cycle' | 'depth' | 'system' }
```

**Fix**: Add formal @param and @returns JSDoc:
```typescript
/**
 * @param taskId - The task that would depend on depId
 * @param depId - The task to validate as a dependency
 * @returns Object with depId, error (null if valid), and type classification
 */
```

---

### MEDIUM-2: Missing @throws/@error Documentation for handleValidationFailure()

**File**: `/workspace/delegate/src/services/handlers/dependency-handler.ts`  
**Lines**: 182-209  
**Severity**: MEDIUM

The method documents the INVARIANT but doesn't document the side effects:

```typescript
/**
 * Handle validation failure - log appropriately and emit failure event
 * INVARIANT: Must emit TaskDependencyFailed event
 */
private async handleValidationFailure(...)
```

**Issue**: Does not document:
- Possible error conditions when emitting events
- The async nature and potential rejection scenarios

**Fix**: Add error handling documentation:
```typescript
/**
 * Handle validation failure - log appropriately and emit failure event
 * INVARIANT: Must emit TaskDependencyFailed event
 * 
 * @fires TaskDependencyFailed - Always emitted with failure details
 * @note Event emission errors are not handled - will propagate to caller
 */
```

---

### MEDIUM-3: withSpawnLock() Missing @template and Error Documentation

**File**: `/workspace/delegate/src/services/handlers/worker-handler.ts`  
**Lines**: 208-248  
**Severity**: MEDIUM

The spawn lock method is well-documented with examples but lacks formal type documentation:

```typescript
/**
 * Execute a function while holding the spawn lock
 * Ensures only one spawn operation runs at a time, eliminating TOCTOU race conditions
 *
 * HOW IT WORKS:
 * Uses promise chaining - each call waits for the previous to complete before executing.
 * ...
 */
private async withSpawnLock<T>(fn: () => Promise<T>): Promise<T>
```

**Fix**: Add generic type documentation:
```typescript
/**
 * @template T - The return type of the protected function
 * @param fn - Async function to execute while holding the lock
 * @returns The result of fn()
 * @throws Rethrows any error from fn() after releasing lock
 */
```

---

### LOW-1: Missing JSDoc for getSpawnDelayRequired()

**File**: `/workspace/delegate/src/services/handlers/worker-handler.ts`  
**Lines**: 255-271  
**Severity**: LOW

Has inline comment but no formal JSDoc with parameters:

```typescript
/**
 * Check if spawn should be delayed due to burst protection
 * PURE: No side effects, returns calculation result
 */
private getSpawnDelayRequired(): { shouldDelay: boolean; delayMs: number }
```

**Fix**: Add @returns documentation explaining the return object structure.

---

### LOW-2: Missing JSDoc for handleSpawnDelayRequired()

**File**: `/workspace/delegate/src/services/handlers/worker-handler.ts`  
**Lines**: 273-285  
**Severity**: LOW

Missing @param documentation:

```typescript
/**
 * Handle spawn delay requirement - log and schedule retry
 * INVARIANT: Must schedule retry via setTimeout
 */
private handleSpawnDelayRequired(delayMs: number, timeSinceLastSpawn: number): void
```

**Fix**: Add @param documentation.

---

## Issues in Code You Touched (Should Fix)

### HIGH-2: EVENT_FLOW.md Contains Outdated Spawn Delay Information

**File**: `/workspace/delegate/docs/architecture/EVENT_FLOW.md`  
**Lines**: 287-306  
**Severity**: HIGH

The EVENT_FLOW.md document describes spawn burst protection but is now outdated:

```markdown
### 1. Spawn Burst Protection (WorkerHandler)

**Problem**: Resource checks happen BEFORE spawn, creating race condition.

**Solution**: 50ms minimum delay between spawns.

...

**Code**: `src/services/handlers/worker-handler.ts:21-48`
```

**Issues**:
1. References "50ms" delay but code now uses configurable `minSpawnDelayMs` (default 10s)
2. Does not mention the new spawn serialization mutex
3. Line references (21-48) are outdated
4. The diagram shows the old non-serialized flow

**Fix**: Update to reflect:
1. Spawn serialization via `withSpawnLock()` as primary protection
2. Minimum delay as defense-in-depth (configurable, not hardcoded 50ms)
3. Updated line references
4. Updated flow diagram showing serialized access

---

### MEDIUM-4: TASK_ARCHITECTURE.md Has Outdated DependencyHandler Line References

**File**: `/workspace/delegate/docs/architecture/TASK_ARCHITECTURE.md`  
**Lines**: 407-438, 440-479  
**Severity**: MEDIUM

The document references specific lines in DependencyHandler that have shifted due to decomposition:

```markdown
#### Dependency Addition (Lines 64-152)
...
#### Dependency Resolution (Lines 157-192)
```

After decomposition, these lines have shifted. The document should reference method names rather than line numbers, or be updated.

---

### MEDIUM-5: Verification Checklist in HANDLER-DECOMPOSITION-INVARIANTS.md Has Unchecked Items

**File**: `/workspace/delegate/docs/architecture/HANDLER-DECOMPOSITION-INVARIANTS.md`  
**Lines**: 204-214  
**Severity**: MEDIUM

The verification checklist has unchecked items:

```markdown
## Verification Checklist

Before merging decomposition:

- [ ] All existing tests pass
- [ ] Coverage >= pre-decomposition levels
- [ ] No new `any` types introduced
- [ ] Ordering invariants preserved (review PR diff)
- [ ] Atomicity invariants preserved
- [ ] Error handling paths unchanged
- [ ] No new mutable state introduced
```

**Fix**: These should be verified and checked off before merge, or converted to a CI verification step. The current state suggests the checklist was not completed.

---

## Pre-existing Issues (Not Blocking)

### INFO-1: test-doubles.ts recordSpawn() Has Minimal Documentation

**File**: `/workspace/delegate/tests/fixtures/test-doubles.ts`  
**Lines**: 542-547  
**Severity**: INFORMATIONAL

The `recordSpawn()` method in TestResourceMonitor has good comments explaining why it's a no-op, but this is a pre-existing pattern in the test doubles.

---

### INFO-2: Worker Handler Constructor Lacks JSDoc

**File**: `/workspace/delegate/src/services/handlers/worker-handler.ts`  
**Lines**: 64-74  
**Severity**: INFORMATIONAL

Constructor parameters are not documented with JSDoc. This is a pre-existing pattern.

---

### INFO-3: DependencyHandler Factory Method Could Use More Examples

**File**: `/workspace/delegate/src/services/handlers/dependency-handler.ts`  
**Lines**: 47-102  
**Severity**: INFORMATIONAL

The `create()` factory method is well-documented but could benefit from a usage example showing error handling. This is a pre-existing enhancement opportunity.

---

### INFO-4: EVENT_FLOW.md Missing DependencyHandler Event Flow

**File**: `/workspace/delegate/docs/architecture/EVENT_FLOW.md`  
**Severity**: INFORMATIONAL

The document does not have a detailed event flow diagram for dependency handling. The TASK_ARCHITECTURE.md has this, but EVENT_FLOW.md focuses on task lifecycle without dependencies. Pre-existing documentation gap.

---

## Summary

### Your Changes:
| Severity | Count |
|----------|-------|
| BLOCKING | 0 |
| HIGH | 1 |
| MEDIUM | 3 |
| LOW | 2 |

### Code You Touched:
| Severity | Count |
|----------|-------|
| HIGH | 1 |
| MEDIUM | 2 |

### Pre-existing:
| Severity | Count |
|----------|-------|
| INFORMATIONAL | 4 |

---

## Documentation Score: 7/10

**Strengths**:
- Excellent new architecture document (HANDLER-DECOMPOSITION-INVARIANTS.md) capturing critical invariants
- Good inline comments explaining PURE functions and INVARIANTS
- Comprehensive characterization tests with clear documentation
- Good use of ARCHITECTURE: comments in code

**Weaknesses**:
- Stale line number references in multiple architecture docs
- Incomplete JSDoc for new extracted methods
- Verification checklist not completed
- EVENT_FLOW.md now outdated regarding spawn protection

---

## Merge Recommendation

**APPROVED WITH CONDITIONS**

The branch can be merged, but the following should be addressed:

**Before Merge (Recommended)**:
1. Update EVENT_FLOW.md spawn burst protection section to reflect serialization
2. Verify and check off the verification checklist items
3. Add missing @param/@returns JSDoc to extracted methods

**After Merge (OK to defer)**:
1. Update TASK_ARCHITECTURE.md line references
2. Consider replacing line references with method name references

---

## Detailed Fix Suggestions

### Fix for HIGH-2 (EVENT_FLOW.md Spawn Protection)

Replace lines 287-306 with:

```markdown
### 1. Spawn Burst Protection (WorkerHandler)

**Problem**: Multiple concurrent `processNextTask()` calls could pass the delay check 
simultaneously before any updated `lastSpawnTime`, causing burst spawning.

**Solution**: Two-layer protection:
1. **Spawn Serialization** (Primary) - `withSpawnLock()` mutex ensures only one 
   spawn operation runs at a time, eliminating TOCTOU race conditions
2. **Spawn Delay** (Defense-in-depth) - Configurable minimum delay between spawns 
   (default: 10s via `minSpawnDelayMs`)

```
With serialization:
  TaskQueued #1 -> acquires lock -> canSpawn? YES -> spawn -> release
  TaskQueued #2 -> waits for lock -> acquires -> sees delay needed -> schedules retry
  TaskQueued #3 -> waits for lock -> acquires -> sees delay needed -> schedules retry
```

**Code**: `src/services/handlers/worker-handler.ts` - see `withSpawnLock()` and 
class-level documentation for incident history.

**Incident References**:
- 2025-10-04: Fork bomb from recovery re-queuing 7 tasks
- 2025-12-06: TOCTOU race condition fixed with mutex
```

---

*Report generated by automated documentation audit tool*
