Always run comprehensive validation before declaring changes complete

After implementation or review, run the relevant focused regression tests followed by the full test suite, linting, formatting/whitespace checks, and workflow/YAML validation. For GitHub Actions changes, also verify security contracts such as trusted-code execution, protected secret usage, trigger safety, and immutable action pinning. Report exact test/file counts and clearly distinguish failures caused by the current change from pre-existing or unrelated formatting/lint issues. Do not treat passing unit tests alone as sufficient evidence that a workflow-heavy change is ready.