TUI tests

packages/tui runs about 170 test files in one bun test process. CI runs it next to up to two other suites on 4-vCPU runners (bun turbo test --affected --concurrency=3 in .github/workflows/check-test.yml), where it has taken 136-146s on Linux and 147-171s on Windows, most of it idle on frame pacing, production timers and sleeps. Most flakes come from waiting on the wrong signal and then running out of frames on a busy runner.

Read the root AGENTS.md Testing section (no globalThis mocks, run from the package directory) and its TUI Stories section. To drive the real TUI, use the opencode-dev skill. For CLI subprocesses, service deadlines, Effect TestClock and turbo test tasks, use the unit-tests skill.

Frame budgets are not time