Fast, Reliable Unit Tests

CI runs bun turbo test --affected --concurrency=3 on 4-vCPU Linux and Windows runners (unit job in .github/workflows/check-test.yml), so each suite shares the CPU with two others, and Windows is the slower leg. Most slow or flaky unit tests here wait on real time, spawn too many processes, or assert wall-clock speed.

Read these first; this skill does not repeat them:

• Root AGENTS.md: the Testing and Style Guide sections.
• packages/app/AGENTS.md Tests (packages/desktop and packages/gui-plugins follow it): one owner per contract, and no production seams for tests.
• packages/ai/AGENTS.md: cassettes. The effect skill: it.effect and it.live.

Sibling skills: tui-tests (OpenTUI renderer tests in tui and cli), app-e2e-tests (Playwright in packages/app/e2e), component-tests (Playwright on stories, packages/stories). This skill owns cli subprocess and service tests.

Know the budget