Implementation
Writing new code: features, endpoints, scripts, components, scaffolds, regexes and one-off utilities.
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- Put a change behind a feature flag
Wraps new behaviour behind a feature flag with a safe default, a kill switch, tests for both paths and a cleanup ticket. Use when shipping a risky change incrementally.
- Add rate limiting to an API
Adds rate limiting to API endpoints with a fitting algorithm, keys, per-tier limits, standard headers, 429 responses and tests. Use when protecting endpoints from abuse or overload.
- Backend engineer
Acts as a backend engineer focused on correct data handling, clear API contracts, explicit failure modes and services that are easy to operate. Use as a builder or reviewer persona for server code.
- Build a REST endpoint end to end
Implements one HTTP endpoint with route, input validation, handler, error mapping and tests in the project's own framework and conventions. Use when adding an API route.
- Build a reusable UI component
Builds a typed, accessible UI component from a description or screenshot, with loading, empty and error states and a usage example. Use when adding a component to a frontend.
- Build a webhook handler
Implements a webhook receiver with signature checks, replay protection, idempotent processing, fast acknowledgement, async work, retries and tests. Use when integrating Stripe, GitHub or similar.
- Frontend engineer
Acts as a frontend engineer who balances UX, accessibility, performance and maintainable components, and checks work in a real browser. Use to build or review web UI.
- Implement a background job
Implements a background or scheduled job with idempotency, retries with backoff, dead-letter handling, timeouts, concurrency limits and observability. Use to move slow work off the request path.
- Implement a feature from a spec
Turns a written spec or ticket into working code that follows the codebase's patterns, with tests and a list of decisions. Use when handing a well-scoped ticket to an agent.
- Implement secure file uploads
Implements secure file uploads with direct-to-storage signed URLs, type and size validation, a malware-scan hook, safe naming and orphan cleanup. Use for backends accepting user files.
- Implement OAuth or OIDC login
Implements login with an OAuth 2 or OpenID Connect provider, covering flow choice, PKCE, state and nonce, token storage, sessions and logout. Use when adding social or SSO login.
- Implement a state machine
Models a business process such as an order, booking or approval as an explicit state machine with states, transitions, guards and side effects, then implements it with exhaustive tests.
- Implement transactional email
Implements transactional email with templates, a provider integration, retries, bounce and complaint handling, and deliverability settings. Use when an app must send receipts, resets or alerts.
- Integrate payments
Implements a payment integration with the provider's official SDK, covering checkout, webhooks, idempotency, refunds and reconciliation. Use when adding one-time payments or subscriptions.
- Integrate a third-party API
Implements a typed client for a third-party HTTP API from its docs, with auth, pagination, retries, rate limits and a test fake. Use when wiring an external service into your code.
- Mobile engineer
Acts as a mobile engineer who designs for flaky networks, battery and memory limits, platform conventions and app-store releases. Use for iOS, Android or cross-platform work.
- Scaffold a new service or library
Creates the minimal production-ready skeleton for a new service or library (layout, config, lint, tests, CI, README) and justifies each choice. Use when starting a new repo or package.
- Write a command-line tool
Designs and implements a small command-line tool with subcommands, help text, exit codes, config precedence and tests. Use when turning a manual workflow into a reusable command.
- Write a streaming file parser
Writes a streaming parser and validator for CSV, log, fixed-width or custom text files that reports malformed records with line numbers instead of crashing. Use for messy input files.
- Write a regular expression
Builds a regular expression from plain-language intent and example strings, explains each part and lists the edge cases it accepts or rejects. Use when you need a tested pattern.
- Write a robust shell script
Writes a portable shell script with strict mode, argument parsing, a dry-run flag, clear errors and idempotent steps. Use when automating a chore you will run more than once.
Not: changing structure without behaviour (refactoring); fixing a defect (debugging); writing tests (testing).