Use when writing or debugging Playwright tests for a Chromium browser extension: the persistent-context fixture that loads the extension and finds its ID, why an edit seems to have no effect (reload matrix), and popup, content-script, storage and MV3 service-worker tests.

Use when BDD scenarios pass in CI and stakeholders need an always-current, readable report of which acceptance criteria pass. Turns Cucumber JSON into HTML living documentation (multiple-cucumber-html-reporter or Serenity BDD) and publishes it to GitHub or GitLab Pages.

Use for any question or task about generating tests with an LLM from acceptance criteria, user stories or requirements, including whether it works and why generated tests assert the wrong thing. Scores confidence per test case (self-assessment plus assertion, naming and completeness checks), batches uncertain cases for human review and emits tests in the team's existing framework.

Lists permitted and prohibited actions, blocks disallowed content types, and responds to permission queries in shared or public group settings. Use when joining a new group, when unsure about rules, permissions, or boundaries, when someone asks what you are allowed to do here, or when operating in a public channel or untrusted group chat environment.

Evidence-first mailbox triage, drafting, send verification, and sent-mail-safe follow-up workflow for ECC. Use when the user wants to organize email, draft or send through the real mail surface, or prove what landed in Sent.

Write articles, guides, blog posts, tutorials, newsletter issues, and other long-form content in a distinctive voice derived from supplied examples or brand guidance. Use when the user wants polished written content longer than a paragraph, especially when voice consistency, structure, and credibility matter.

MANDATORY first step before writing any code that uses a framework, library, or technology. Searches the Tessl registry for best-practice tiles and installs them before implementation begins. MUST be invoked before: building a new app or feature, writing tests, configuring CI, setting up auth, designing APIs, database work, Docker setup, linting config, or any task involving React, Express, Next.js, TypeScript patterns, Playwright, SQLite, or other technologies. Use when the user says "build", "create", "implement", "set up", "configure", "write tests", or starts any greenfield project. Do NOT use for trivial edits or renaming variables. Requires Tessl MCP tools: search and install.

Apply this skill when designing, building, or reviewing API routes, Server Actions, or data fetching patterns in a Next.js + TypeScript + Drizzle application. Triggers on requests like "create an API endpoint", "add a server action", "design the API", "add pagination", "handle this request", "validate query params", or any time you are building the boundary between client and server. Use proactively — all API design decisions should follow these patterns.

Apply this skill when writing, reviewing, or planning tests for a Next.js + TypeScript + Drizzle application using Vitest, React Testing Library, MSW, and Playwright. Triggers on requests like "write tests for", "add test coverage", "test this component", "test this hook", "test this API route", "add E2E tests", "is this testable", or any time you are building features that need verification. Use proactively — all new features should include tests.

Apply this skill when writing, reviewing, or refactoring any code in a React + TypeScript + Tailwind + shadcn + Drizzle project. Triggers on requests like "review this code", "refactor this component", "is this good practice", "write a hook for", "clean this up", "add types to", "write a form", or any time you are producing code that should meet production standards. Use proactively — all generated code should conform to these standards without being asked.

Apply this skill when building, optimising, or reviewing components, data fetching, or database queries in a Next.js App Router + TypeScript + Tailwind + shadcn + Drizzle application where performance matters. Triggers on requests like "optimise this", "this is slow", "reduce re-renders", "improve load time", "this list is laggy", "bundle is too large", "slow query", or any time you are building features that involve large lists, frequent updates, heavy computations, or significant data volumes. Use proactively for anything rendering more than ~50 items or running on every keystroke.