Codex CLI Prompt Examples (2026) — 50+ Real-World Use Cases

$ codex "src/utils/validation.ts has 3 copies of email format validation logic — extract to a validateEmail() function, don't change callers' interfaces"

$ codex "processOrder() is over 200 lines — split into single-responsibility sub-functions following SRP, preserve existing behavior"

$ codex "Replace all axios usage in src/ with the native fetch API, remove the axios dependency, keep TypeScript types correct"

$ codex "Replace all hardcoded HTTP status codes (200, 404, 500, etc.) in src/ with an HttpStatusCode enum, create src/constants/http.ts"

$ codex "Audit all catch blocks in src/api/, replace console.error with logger.error, ensure the full error object is passed through"

$ codex "Rewrite all Promise.then() chains in src/services/user.js as async/await, preserve logic exactly"

$ codex "Add concrete TypeScript types to all 'any' types in src/api/client.ts — infer from function signatures and usage, no 'as' casts"

$ codex "src/store/index.ts is 500+ lines — split into feature modules (user, cart, orders), keep exports backward-compatible"

$ codex "Generate Jest unit tests for every exported function in src/utils/date.ts, covering normal inputs, edge cases, and error paths"

$ codex "Run npx jest --coverage, find files below 80% coverage, add missing test cases to bring them up"

$ codex "Generate supertest integration tests for the /api/users route, covering GET/POST/PUT/DELETE, including auth and permission checks"

$ codex "Write a Playwright E2E test for the login flow: navigate to /login → fill email and password → click submit → assert redirect to /dashboard"

$ codex "Create a user factory function using faker.js for registration tests, support traits (admin, premium, banned)"

$ codex "Run npm test, find all failing test cases, diagnose root cause, fix the bug in either the test or implementation (only fix the wrong side)"

$ codex "Generate React Testing Library snapshot tests for src/components/Button.tsx, covering all variants (primary, secondary, danger)"

$ codex "Analyze this error: TypeError: Cannot read property 'id' of undefined at UserCard.tsx:42 — find the root cause and fix it"

$ codex "Run npx tsc --noEmit and fix all TypeScript errors — no 'any' or 'as' casts as workarounds"

$ codex "Check all useEffect hooks in src/hooks/ for uncleaned subscriptions, timers, or event listeners — fix any leaks"

$ codex "src/api/search.ts has a race condition where old responses overwrite newer ones — fix using AbortController"

$ codex "Audit all database queries in src/db/queries.ts — replace string concatenation with parameterized queries to prevent SQL injection"

$ codex "Analyze why ProfilePage re-renders excessively (React Profiler log in debug.log) — fix with useMemo and useCallback where appropriate"

$ codex "Add complete JSDoc comments to all exported functions in src/utils/ — include @param, @returns, @throws, and a usage example for each"

$ codex "Generate a complete README.md from the project structure and package.json — include overview, install, usage examples, API docs, contributing guide"

$ codex "Analyze all Express routes in src/routes/ and generate an OpenAPI 3.0 spec (YAML), including request/response schemas and examples"

$ codex "Parse 'git log --oneline' for the last 50 commits, organize into a v2.0.0 CHANGELOG.md entry following Conventional Commits format"

$ codex "Add inline comments to src/algorithms/dijkstra.ts explaining each key step — target audience: developers unfamiliar with graph algorithms"

$ codex "Audit src/auth/: check JWT validation completeness, password hashing algorithm strength, CORS config, and whether secrets leak into logs"

$ codex "Run npm audit, upgrade each high/critical vulnerability to a safe version, run tests to confirm nothing breaks"

$ codex "Use eslint-plugin-complexity to find functions with cyclomatic complexity > 10, provide refactoring suggestions to simplify them"

$ codex "Scan the entire codebase for hardcoded API keys, passwords, tokens — replace with environment variables, update .env.example"

$ codex "Fix all ESLint and Prettier violations in src/ per .eslintrc.json and .prettierrc — ensure CI checks pass"

$ codex "Add a lastLoginAt field (TIMESTAMP, nullable) to the User model — generate a Prisma migration file including rollback script"

$ codex "Analyze src/db/userQueries.ts for N+1 query patterns — optimize with JOIN or DataLoader batch loading"

$ codex "Read prisma/schema.prisma and generate a human-readable database design doc (Markdown) including ER diagram description and field explanations"

$ codex "Create prisma/seed.ts with dev environment seed data: 10 users (1 admin), 20 products, 50 orders"

$ codex "Write a Node.js script to migrate MongoDB 'users' collection to PostgreSQL 'users' table — handle type coercion, nulls, batch insert 100 rows at a time"

$ codex "Generate a GitHub Actions CI workflow for this Node.js project: Node 18/20 matrix, lint, build, test, coverage upload to Codecov"

$ codex "Create a GitHub Actions release workflow: on tag push, run tests → build → publish to npm → generate GitHub Release with CHANGELOG"

$ codex "Write a multi-stage Dockerfile for this Express app (Node 18 Alpine), add docker-compose.yml with PostgreSQL and Redis, include health checks"

$ codex exec "Replace all 'var' keywords in .js files with 'const' or 'let' based on reassignment — skip node_modules"

$ codex exec --approval-mode full-auto "Run eslint --fix and prettier --write, then run tests — if tests fail, roll back all changes"

$ codex "Convert src/components/UserList.tsx from class to function component with Hooks — add TypeScript types, keep the props interface identical"

$ codex "Implement pages/api/users/[id].ts as a full REST API (GET/PUT/DELETE) with auth middleware, zod input validation, and error handling"

$ codex "Generate pytest tests for app/services/order_service.py using unittest.mock for DB calls — cover all business logic branches"

$ codex "Implement the Storage interface defined in internal/storage/interface.go using PostgreSQL (pgx/v5), include connection pooling and error handling"

$ codex "Create a DRF ViewSet for the Django User model with custom permissions (users can only modify their own data), filtering, search, and pagination"