Claude Code Skills That Fix Their Own Mistakes: Building Verification Loops

Package your build-test-fix cycle as a Claude Code skill and every session checks and corrects its own work automatically — without waiting for you to prompt it.

A verification loop is a cycle Claude Code runs until the work actually passes: take action → run checks → if failures, fix them → recheck → repeat. Out-of-the-box Claude Code catches tool errors inline, but packaging the loop as a dedicated skill makes it automatic, consistent, and composable across any session.

Adding verification to CLAUDE.md (simplest form):

## Verification commands
After any code change, always run:
1. `pnpm run lint` — must exit 0
2. `pnpm run test --changed` — must exit 0 with no failing tests
3. `pnpm run build` — must produce no TypeScript errors
Fix any failures before considering the task complete.

Claude reads these instructions and applies them every session — no explicit /verify call needed.

Packaging as a reusable skill:

<!-- .claude/skills/verify-pr/prompt.md -->
Run these checks in order. If any fail, fix the failures, then re-run from step 1.
Stop only when all three exit 0. Report: rounds taken and what was fixed each round.

1. `pnpm run lint`
2. `pnpm run test`
3. `pnpm run build`

Call it explicitly or chain it after another task in one prompt:

Refactor the auth module to use the new TokenService interface, then /verify-pr

Claude does the refactor, then immediately enters the verification loop — no separate prompt.

Four patterns:

Pattern	When to reach for it
Embedded in CLAUDE.md	Default — applies to every session automatically
Standalone skill (/verify)	Cross-cutting checks: security scans, a11y audits
Chained after a task	Keeps implementation and verification in one prompt
Tied to a hook	Runs automatically before git commit, impossible to skip

Hook-based automatic verification:

// .claude/settings.json
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "hooks": [
          {
            "type": "command",
            "command": "if echo \"$CLAUDE_TOOL_INPUT\" | grep -q 'git commit'; then pnpm run lint && pnpm run test; fi"
          }
        ]
      }
    ]
  }
}

This fires lint + tests automatically before any git commit Bash call — not just when Claude remembers to check.

Cost note: Each verification round uses tokens for check output + Claude's analysis. On a fast suite (<10s) the overhead is negligible; on a slow one, limit to changed files (--changed) so loops stay quick.

Sources: Building verification loops in Claude Code with skills — claude.com · Hooks reference — Claude Code Docs · Skills — Claude Code Docs