e2e-tests-studio

The e2e-tests-studio skill generates Playwright end-to-end tests for the Mastra studio playground UI, and is marked required whenever files in packages/playground-ui or packages/playground are modified. Its central principle is testing product behavior rather than UI states: tests must verify that features actually work (an LLM provider selection is used in the request payload, a created agent persists and appears in the list, a workflow executes tools in order) instead of merely asserting that a dropdown opens or a spinner shows.

It enforces a strict three-level BDD structure — an outer describe naming the unit under test, inner 'when …' describe blocks each expressing exactly one precondition, and each test asserting exactly one observable outcome — mirroring the project's MSW tests and its e2e-bdd lint rule. The skill walks through understanding feature intent (user problem, expected outcome, data flow, persistence, downstream effects), building and starting the playground kitchen-sink server, and mapping feature categories to behavior tests via a detailed table (agent configuration, LLM provider selection, tool execution, workflow execution, chat/streaming, MCP server tools, memory/persistence, error handling). It includes test-structure templates and patterns such as intercepting API routes to verify the selected provider is actually used. It requires the Playwright MCP server and pins the model to claude-opus-4-5.

It targets contributors to the Mastra codebase working on the playground/studio frontend. Use cases include validating new playground features, refactors, and bug fixes with behavior-focused e2e coverage that survives page reloads and checks real downstream effects rather than superficial rendering.