adding-tests
Use when adding tests for a new modality (vision/embeddings/TTS/STT/realtime/image-gen/video-gen), a new AI provider, or a new SDK feature. Picks the right per-domain suite, wires the right helpers, sets the right capability flag, and avoids the four traps that broke past contributions (loose error matchers, missing capability gate, monolithic test file, manual skip plumbing).