Build–Test–Fix Loop

Loop Engineering — the single most-demoed loop pattern: a builder writes code and a checker runs tests, typecheck and lint and reports exactly what broke. They pass work back and forth until it's clean. A one-shot agent ships its bugs; this loop catches them.

🎯 Goal

Implement the next item on the plan, then run the full check gate (tests + typecheck + lint), feed every failure back as the next instruction, and repeat until the build is green.

⏱️ Schedule

Suggested interval: 10m (or run until done on a feature).

▶️ Run it

/loop 10m "Build the next item on the plan, then run tests, typecheck and lint. Feed every failure back as the next instruction and fix it. Add a test for anything that lacked coverage. Stop when the build is green and the checker has nothing left to report."

🔁 Iteration steps

1. Build — implement the next plan item.
2. Check — the test-runner hook runs tests, typecheck and lint automatically.
3. Reason — collect every failure into a concrete fix list.
4. Act — fix each; add tests with /generate-tests for uncovered paths.
5. Observe — re-run the gate; loop until fully green.

🛑 Stopping condition

Tests, typecheck and lint all pass and the checker reports nothing outstanding.

💰 Budget & guardrails

Cap iterations or spend so a stubborn failure can't spin forever — surface anything that fails the same way twice for human eyes.

🧩 Referenced components

• agent:development-team/test-runner — runs and interprets the check gate.
• hook:testing/test-runner — fires the suite automatically each pass.
• command:testing/generate-tests — covers gaps the loop uncovers.

💡 Example

Implementing a new endpoint, the loop catches a type error, then a failing integration test, then a lint warning — fixing each in turn — and exits only when all three gates are green.