feat: Add Stop hook for quality enforcement

[CarGDev]

Summary

Add a Stop hook that fires when the agent wants to complete a task, enabling quality enforcement.

Why It's Needed

• Quality Gates: Ensure tests ran before claiming "done"
• Enforce Standards: Require commit, lint pass, etc.
• Prevent Premature Completion: Block if work is incomplete
• Consistency: Same standards applied every session

Hook Interface

interface StopInput {
  sessionId: string
  reason: string              // Agent's completion message
  toolsUsed: string[]         // Tools invoked this session
  filesModified: string[]     // Files changed
  filesCreated: string[]      // New files
  duration: number            // Session duration in ms
}

interface StopOutput {
  decision: "approve" | "block"
  continuePrompt?: string     // If blocked, what to tell agent
}

Example: Require Tests

export const requireTestsOnStop: StopHook = async (input) => {
  // Check if source files were modified
  const sourceFiles = input.filesModified.filter(f => 
    f.endsWith(".ts") && !f.includes(".test.") && !f.includes(".spec.")
  )
  
  if (sourceFiles.length === 0) {
    return { decision: "approve" }
  }
  
  // Check if tests were run
  const testCommands = ["npm test", "bun test", "vitest", "jest"]
  const testsRan = input.toolsUsed.some(t => 
    testCommands.some(cmd => t.includes(cmd))
  )
  
  if (!testsRan) {
    return {
      decision: "block",
      continuePrompt: `You modified ${sourceFiles.length} source files but didn't run tests. Please run tests before completing.`
    }
  }
  
  return { decision: "approve" }
}

Built-in Stop Hooks (Optional)

require-tests

• Block if source files changed but no test command ran

require-lint

• Block if files changed but no lint command ran

require-commit

• Block if files modified but not committed

no-console-log

• Block if console.log statements were added

no-todo-comments

• Warn if TODO comments were added

Configuration

{
  "hooks": {
    "builtin": {
      "require-tests-on-stop": false,
      "require-lint-on-stop": false,
      "require-commit-on-stop": false
    },
    "Stop": [
      {
        "name": "custom-quality-gate",
        "script": ".codetyper/hooks/quality.ts"
      }
    ]
  }
}

Acceptance Criteria

• Stop hook fires when agent wants to complete
• Hook receives list of modified files and tools used
• Hook can approve or block completion
• Blocked completion returns prompt to agent
• Built-in require-tests hook (optional)
• Configurable per-project

Effort Estimate

1 day

Depends On

• feat: Implement hooks system (PreToolUse, PostToolUse) #101 (Hooks system)