Spec Lock

Spec-Lock: Documentation Synchronization

Overview

Spec-Lock prevents documentation rot by maintaining bi-directional sync between code and specifications. It treats documentation as executable code that must stay synchronized with implementation.

The Problem It Solves

Documentation Rot: In agentic workflows, code evolves faster than docs. Users hate writing documentation, and agents frequently ignore old instructions.

Spec-Lock Solution: Automatic synchronization that detects drift and keeps context perfectly synced with reality.

How It Works

1. Post-Edit Analysis (PostToolUse Hook)

Every time a file is edited:

• Analyzes semantic intent of the change
• Compares against CLAUDE.md and SPEC.md
• Detects drift between code and docs

2. Conflict Detection

Two scenarios trigger sync:

Scenario A: Code Drift

• Code violates the spec (e.g., wrong auth method)
• Plugin asks: "Revert code or update spec?"

Scenario B: Spec Evolution

• Code introduces new logic not in spec
• Plugin asks: "Update SPEC.md to match code?"

3. Auto-Update

Uses headless Claude to:

• Generate documentation patches
• Update dependent docs automatically
• Maintain knowledge graph of dependencies

When to Use

Activate Spec-Lock when:

• Changing API endpoints or parameters
• Modifying authentication flows
• Updating database schemas
• Changing configuration values
• Implementing new features
• Refactoring existing code

Usage

Automatic Mode

With PostToolUse hooks:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit(*)|Write(*)",
        "command": "python3 /a0/usr/plugins/spec-lock/spec-lock.py --check"
      }
    ]
  }
}

Manual Commands

# Check a file for drift
python3 /a0/usr/plugins/spec-lock/spec-lock.py --check <file>

# Register a new dependency
python3 /a0/usr/plugins/spec-lock/spec-lock.py --register <code> <spec> [priority]

# Show sync status
python3 /a0/usr/plugins/spec-lock/spec-lock.py --status

# Force full sync
python3 /a0/usr/plugins/spec-lock/spec-lock.py --sync

Configuration

Priority Rules

Create /a0/usr/plugins/spec-lock/spec-priorities.yaml:

files:
  "src/auth/**":
    spec_source: "AUTH_SPEC.md"
    priority: code  # Code wins (security)
  
  "docs/api/**":
    spec_source: "API_SPEC.md"
    priority: spec  # Spec wins (contracts)
  
  "src/models/**":
    spec_source: "DATA_MODEL.md"
    priority: ask   # Always ask user

Priority Options:

• code: Implementation is source of truth
• spec: Documentation is source of truth
• ask: Prompt user for decision

Drift Detection

Spec-Lock detects these drift types:

Function Signature Mismatch

// Code has:
function createUser(name, email, role)

// Spec says:
function createUser(name, email)
// DRIFT: 'role' parameter not documented

API Endpoint Changes

// Code changed from:
POST /api/v1/users

// To:
POST /api/v2/users
// DRIFT: Version change not in API_SPEC.md

Configuration Changes

// Code changed:
const timeout = 5000;  // Was: 30000

// Spec still says:
"Request timeout: 30 seconds"
// DRIFT: Config value changed

Knowledge Graph

SQLite database tracks dependencies:

CREATE TABLE spec_dependencies (
    code_file TEXT,
    spec_file TEXT,
    last_sync TIMESTAMP,
    drift_detected BOOLEAN,
    priority TEXT
);

Example Dependencies:

• src/auth/login.ts → AUTH_SPEC.md
• src/api/users.js → API_SPEC.md
• src/models/user.js → DATA_MODEL.md

Sample Workflow

Developer Edits Authentication

# Developer changes JWT expiry
vim src/auth/login.ts
# const expiry = '1h';  # Changed from '24h'

Spec-Lock Detects Drift

⚠️  DRIFT DETECTED in src/auth/login.ts

AUTH_SPEC.md says:
  "Session tokens expire after 24 hours"

Code implements:
  "Session tokens expire after 1 hour"

Priority: CODE WINS (security)
Auto-updating AUTH_SPEC.md...
✅ Documentation synchronized

Sync Status Updated

📊 SYNC STATUS:
  Total Dependencies: 47
  In Sync: 47
  Drifted: 0
  Last Sync: 2026-02-12 13:00:00

Integration

With Debt-Sentinel

Spec-Lock runs after Debt-Sentinel clears edits:

1. Debt-Sentinel: Check for anti-patterns
2. Edit allowed to proceed
3. Spec-Lock: Check for doc drift
4. Auto-sync if possible

With Compound Engineering

Part of enhancement pipeline Level 4:

Level 4: Documentation Sync
  └─ Update all affected specs
  └─ Generate migration guides
  └─ Verify sync status

Success Metrics

• Sync Rate: % of dependencies in sync
• Drift Detection Time: Time to detect changes
• Auto-Resolution Rate: % resolved automatically
• Documentation Freshness: Average age of specs

Troubleshooting

Database Locked

rm /a0/usr/plugins/spec-lock/spec_dependencies.db

Missing Dependencies

# Register manually
python3 /a0/usr/plugins/spec-lock/spec-lock.py --register src/api/users.js API_SPEC.md spec

False Positives

Adjust priority rules in spec-priorities.yaml:

files:
  "src/internal/**":
    priority: code  # Internal tools don't need strict spec sync

Part of the Essential 2026 Plugin Suite

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