Browse reusable Agent Skills, each with a clear purpose and practical guidance.
React component testing patterns including components, hooks, context, and forms. Covers Vitest Browser Mode with vitest-browser-react (preferred) and @testing-library/react. Use when testing React applications. For general UI testing patterns, see the front-end-testing skill.
Get a rigorous second opinion on finished work, preferably from a *different* AI provider's CLI agent — codex, claude, gemini, or cursor-agent — then run a constructive back-and-forth until both agents genuinely agree. If no independent provider can be reached, fall back to a fresh same-provider agent with no inherited context and clearly label the reduced independence. Use when the user says "double check this", "verify my work", "get a second opinion", "have another model check", "cross-check with codex/gemini", "is this actually right?", or before merging or shipping high-stakes, complex, or security-sensitive work.
Use when existing code has untestable dependencies that prevent writing tests -- direct construction of collaborators, static or global function calls, tight coupling to external systems, or singleton access patterns. Specifically for identifying substitution points (seams) that make legacy or tightly-coupled code testable without editing at the call site. Do NOT use for greenfield TDD (see tdd), general test writing patterns (see testing), or refactoring already-tested code (see refactoring).
Evaluates test quality using Dave Farley's 8 properties. Use when reviewing tests, assessing test suite quality, or analyzing test effectiveness against TDD best practices.
Examines the git history of files changed in the current branch to identify potential regressions, re-introduced bugs, or changes that conflict with past fixes. Cross-references current changes against prior commits on the same code paths.
Reviews changed React/TSX code for component design, hooks misuse, performance, accessibility, and state management issues. Reports findings with severity and concrete fix recommendations. Operates on files changed vs main.
Reviews changed code for code smells across design, implementation, tests, and dependencies. Reports findings with severity and concrete fix recommendations. Operates on files changed vs main.
Explains code for experienced engineers. Covers what changed, why it works, non-obvious decisions, gotchas, and data/control flow. Defaults to git diff vs main; accepts an optional file or path argument.
Thorough FXA-specific commit review using parallel specialist agents. Covers security, TypeScript, logic/bugs, test quality, and architecture. Agents explore call sites, git history, and monorepo conventions.
Fast single-pass FXA-specific commit review covering security, conventions, logic/bugs, tests, and migrations. No subagents — runs directly in the main context.