Build Your First Autonomous Loop with Claude Code Skills (Practical Guide)

You've used Claude Code interactively: type a request, watch it work, type again. This guide walks you through the jump that defines loop engineering — building a loop where the system prompts the agent, verifies its output, retries on failure, and only involves you at a final checkpoint.

The Target: A Self-Verifying Feature Loop

By the end you'll have a loop that takes a small feature spec and:

1. Plans the implementation as bite-sized tasks
2. Implements each task test-first
3. Verifies every change against checks it cannot skip
4. Retries with error context when verification fails
5. Stops and asks a human only before the merge

No new infrastructure required — everything below uses Claude Code primitives plus installable skills.

Step 1: Write the Loop Contract

A loop without a machine-checkable definition of done will run forever or stop early. Write the contract before starting the loop, in a file the agent can read:

# CONTRACT.md
Feature: rate-limit middleware for /api/submit
Done means:
- [ ] All existing tests still pass (npm test)
- [ ] New tests cover 429 behavior and header output
- [ ] npx tsc --noEmit is clean
- [ ] No changes outside src/middleware/ and tests/

The last line is a scope fence — loops fail more often by wandering than by stopping.

Step 2: Install the Procedure Layer (Skills)

A loop without disciplined procedures just makes mistakes faster. Two collections cover the methodology:

• Superpowers — brainstorming, plan-writing, test-driven development, systematic debugging, and subagent-driven execution as composable skills. Its TDD skill is the engine of this loop: every task becomes RED → GREEN → REFACTOR.
• Everything Claude Code — ships the loop infrastructure around the skills: hooks for deterministic checks, reviewer sub-agents, and a dedicated loop-operator agent.

Install once; the loop loads them on demand.

Step 3: Externalize State

Context windows compact; files don't. The loop's memory lives outside the conversation:

• Plan file — the task breakdown, updated as tasks complete
• Task list — Claude Code's task tools (or a plain TODO.md) tracking pending/in-progress/done
• Git worktree — isolate the loop's changes so parallel work never collides

The test of good state design: kill the session mid-loop, start a fresh one, and the loop should resume from files alone.

Step 4: Wire Checkers the Agent Cannot Skip

This is the difference between a demo and a production loop. Three verification layers, from cheap to thorough:

1. Hooks — a PostToolUse hook that runs the linter after every edit; a pre-commit hook that blocks failing tests. Deterministic, zero-trust.
2. Test suite as gate — the contract's npm test line. For web work, add webapp-testing or playwright-skill so the loop can verify actual browser behavior, not just unit logic.
3. Fresh-eyes review — dispatch a reviewer sub-agent with only the diff and the contract. Fresh context means it can't inherit the implementer's blind spots. Two-stage works best: one pass for spec compliance, one for code quality.

Rule of thumb from working loop setups: trust the checker, not the transcript. An agent saying "all tests pass" is a claim; a hook that ran the tests is a fact.

Step 5: Close the Loop with Bounded Retries

Failure handling is where loops earn their keep:

verify → fail → feed error + contract back → retry (max 3)
     → still failing → stop, summarize attempts, escalate to human

The retry prompt matters: include the original contract and the specific failure, not the whole history. Bounded retries with escalation beat both infinite loops and give-up-on-first-error.

Step 6: Place the Human Checkpoint

Full autonomy everywhere except one narrow gate: before irreversible actions — merging to main, deploying, publishing. The loop prepares everything (branch pushed, PR description drafted, checks green) and stops. You review a finished, verified unit of work instead of babysitting forty turns.

Common First-Loop Mistakes

• Vague contract — "improve the code" cannot terminate. Every contract line must be checkable by a command.
• Skipping the scope fence — loops that may touch anything eventually will.
• Checker theater — asking the agent to review its own work in the same context. Fresh sub-agent or it doesn't count.
• Autonomy before evals — grant longer leashes only after your checkers have caught real failures.

Where to Go Next

This single-feature loop is the atom of loop engineering. The molecule — parallel loops across worktrees, cron-triggered maintenance loops, loop-until-dry discovery sweeps — composes the same five layers. Start with the Loop Engineering guide for the full operator loop stack, and make sure your harness is solid before you scale the loops running on top of it.

Related: Harness Engineering Guide · Superpowers collection · Best testing skills