# Jimmymalhan Codereview Pilot Backend Engineer > Phase 1: DISCOVER - Skill: `tomevault-io/jimmymalhan-codereview-pilot-backend-engineer` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/jimmymalhan-codereview-pilot-backend-engineer` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/jimmymalhan-codereview-pilot-backend-engineer/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/jimmymalhan-codereview-pilot-backend-engineer --- ## Phase 1: DISCOVER ### Sub-Agent: `APIScout` (model: haiku) - **Tools**: Grep, Glob, Read - **Prompt**: Find all routes in src/server.js and src/routes/. List handlers, middleware. Find missing validation or error handling patterns. - **Output**: `{ endpoints[], handlers[], missing_validation[], missing_error_format[] }` - **Gate**: endpoints listed ## Phase 2: PLAN ### Sub-Agent: `BackendPlanner` (model: sonnet) - **Prompt**: Design which endpoints to add/modify. For each: validation rules, error format, retry config, logging. Create checklist. - **Output**: `{ endpoint_plan[{path, method, validation, errors, retry}], checklist[] }` - **Gate**: plan has >= 1 endpoint ## Phase 3: IMPLEMENT ### Sub-Agent: `RouteBuilder` (model: haiku) - **Tools**: Read, Write, Edit, Bash - **Prompt**: Implement ONE endpoint at a time. Order: validation → handler → error format → logging. Copy-paste error template from skill (never invent). Run `npm test` after each edit. - **Output**: `{ endpoint, files_changed[], test_pass: boolean }` - **Gate**: endpoint works AND test passes ## Phase 4: VERIFY ### Sub-Agent: `APITester` (model: haiku) - **Tools**: Bash, Read - **Prompt**: Run `npm test`. Restart server (`pkill -f "node src/server"; sleep 2; npm start &`). Test happy/error/retry paths. Verify health: `curl http://localhost:3000/health`. - **Output**: `{ test_output, endpoints_verified[], health_ok: boolean, coverage }` - **Gate**: all endpoints respond correctly AND health returns 200 ## Phase 5: DELIVER ### Sub-Agent: `BackendPackager` (model: haiku) - **Prompt**: Update CHANGELOG. Commit. Notify user: server status, endpoints added, health check result. - **Output**: `{ commit_sha, server_status, health_ok, endpoints_added[] }` - **Gate**: committed AND health verified ## Contingency IF endpoint breaks existing tests → contingency L1 (fix that endpoint only). IF health check fails after restart → check server logs, fix, retry (max 2). ## Live Feedback Handler IF user reports "API returns 500" or "endpoint broken" → classify as High → hotfix the specific route → restart server → verify health → notify user "Fixed. Refresh." ## Server Lifecycle MUST restart server after ANY file edit in src/. Express does not hot-reload. Always verify with `curl http://localhost:3000/health` after restart. --- # Backend Engineer Skill **Purpose**: Enable backend domain expertise for production APIs and server logic. **When to use**: Creating or reviewing backend features, API routes, handlers, pipeline logic, or external integrations. **Project customization**: Add `.claude/skills/backend-engineer/PROJECT.md` with project-specific rules (route patterns, error format, validation schemas). See docs/SKILLSETS.md → "Add Skills to Customize FE/BE". ## Create → Handle → Run (E2E) ### Create - Add routes in `src/server.js` or `src/routes/` - Add pipeline logic in `src/local-pipeline.js` - Add custom skills in `src/custom-skills/` - Validate inputs, add retry/timeout for externals - Structure errors: type, message, traceId, suggestion, retryable ### Handle - Every endpoint: validation → processing → response - External calls: retry with backoff, timeout, fallback - Log critical ops with structured format - Ensure every new endpoint reachable from UI ### Run ```bash npm test # Must pass npm start # Server on :3000 curl http://localhost:3000/health ``` - Restart server after backend changes (no hot-reload) - Verify health endpoint - Test error paths (400, 403, 404, 503) - Capture test output for CONFIDENCE_SCORE ## Domain Expertise As a backend engineer with this skill, you are expert in: - Express/Node.js patterns - Request validation and error responses - Retry with exponential backoff - Timeout control - Structured logging - Idempotency for unsafe operations - Graceful degradation ## Must-Do Checklist ### 1. Validation Every endpoint must: - Validate required fields and types - Return `400` + message for invalid input - Return `403` for unauthorized - Return `404` if resource missing - Validate state before transitions ### 2. Error Format Every error must include: ```javascript { error: 'error_code_name', message: 'User-friendly message', traceId: 'trace-xxx', // when available status: 400|403|404|500|503, suggestion: 'What to do next', retryable: true|false, retryAfter: 2 // seconds, if retryable } ``` ### 3. External Calls - Retry with exponential backoff (max 2 retries) - Timeout (default 60s) - Graceful fallback on failure ### 4. Structured Logging ```javascript logger.info('operation_name', { traceId, userId, input: sanitizedInput, timestamp }); ``` ### 5. Idempotency For unsafe operations, use request ID to prevent double-processing. ### 6. API Surface - Every supported endpoint must be reachable from the UI - Restart server after backend changes (no hot-reload) - Verify with `curl http://localhost:3000/health` ## File Locations | Type | Path | |------|------| | Server | `src/server.js` | | Routes | `src/routes/` or inline in server | | Pipeline | `src/local-pipeline.js` | | Custom skills | `src/custom-skills/` | ## Related Skills - `backend-reliability` – Full reliability checklist - `evidence-proof` – Run tests before claiming done ## Verification Before claiming done: - [ ] All inputs validated - [ ] All errors have type, message, suggestion - [ ] External calls have retry + timeout - [ ] Structured logging for critical ops - [ ] `npm test` passes - [ ] Health endpoint verified - [ ] Every new endpoint reachable from UI - [ ] Aligns with `.claude/rules/backend.md` and `backend-proof.md` --- > Source: [jimmymalhan/codereview-pilot](https://github.com/jimmymalhan/codereview-pilot) — distributed by [TomeVault](https://tomevault.io).