coding-agent

Coding Agent

When to Use

• User asks to implement a feature, fix a bug, or modify code
• User asks to build, create, or set up a project or component
• Any task that involves writing or modifying source code
• Always active: enforces the structured workflow for all coding tasks

How to Execute

Phase 1: Read & Understand

1. Read the relevant source files to understand the current state.
2. Identify the exact files, functions, and lines that need to change.
3. Check for existing tests, types, and conventions in the codebase.
4. Read any related config files, schemas, or documentation.

Phase 2: Plan

1. State what will change and what will NOT change.
2. List every file to be modified or created.
3. If the change is non-trivial (>20 lines), describe the approach before writing code.
4. If the request conflicts with existing architecture, state the conflict and options.
5. Get user confirmation on the plan for large changes.

Phase 3: Implement

1. Make the minimum change that satisfies the requirement.
2. Match existing code style — indentation, naming, patterns.
3. Add JSDoc to public functions. Use TypeScript strict types.
4. Handle errors explicitly — no silent swallows, no bare catch {}.
5. Add timeouts to external I/O calls.
6. Do NOT refactor unrelated code unless explicitly asked.

Phase 4: Test

1. Run existing tests to ensure nothing is broken: pnpm test.
2. If new behavior was added, write tests that prove it works.
3. Tests must cover: happy path, error case, edge case.
4. Mock external boundaries in unit tests; keep real provider calls in explicit integration tests.

Phase 5: Verify

1. Run pnpm build to confirm TypeScript compiles cleanly.
2. Run pnpm test to confirm all tests pass.
3. List every file modified and summarize each change.
4. Identify the most likely failure point in the new code.

Examples

Input: "Add a health check endpoint to the API" Workflow: Read index.ts and Fastify setup → Plan: add GET /health route → Implement the route → Write test → Verify build + tests pass.