Regression Checker

Runs the existing test suite to ensure no regressions after implementation changes.

Purpose & Scope

• Detect test framework (pytest/jest/vitest/go test/etc.) and test dirs.
• Execute full suite; capture results for Story quality gate.
• Return PASS/FAIL with counts/log excerpts; never modifies Linear or kanban.

When to Use

• Invoked by ln-500-story-quality-gate Pass 1 (after ln-501)
• Code quality check passed
• Before test planning pipeline (ln-510)