Root cause: the affected-tests runner called runAllSuites() on critical-path
changes (running every suite including install/slow on all matrix cells including
Windows), and pickAffectedTests injected DEFAULT_SMOKE_TESTS (an install test)
as the empty-selection fallback — causing install suite tests to run on PR lanes
where they are push-only per docs/TESTING-SUITES.md.
Fix: PR_EXCLUDED_SUITES filter at the pickAffectedTests chokepoint strips
install/slow from every selection path (direct-change, reverse-index, stem-match).
Empty selection now returns [] and the caller runs the unit suite as smoke.
Critical-path fallback replaces runAllSuites with PR_FULL_SUITES
(unit, integration, security). suiteOf exported from run-tests.cjs
(with require.main guard) so affected-tests-lib reuses canonical detection.
Fixes#370
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>