Adversarial doubt cycle on a plan or design before any code exists — distinct from post-hoc code review. Use when the user asks to doubt this, stress-test a design before building it, poke holes in a plan, find the flaw in an approach, or before committing to a non-trivial architecture or design decision.
Run a test suite repeatedly, compute a per-test flakiness rate, quarantine the nondeterministic ones. Use when the user asks whether a test is flaky, to audit test health, why a test sometimes fails, to find flaky tests, or as a scheduled nightly or weekly test-health routine.
Resolve git merge or rebase conflicts hunk-by-hunk with mandatory post-resolution verification. Use when the user hits a merge conflict, asks to resolve conflicts, fix the merge, or handle a rebase conflict, or when git reports CONFLICT / "both modified".
Lint and structure-check a SKILL.md — frontmatter, line budget, trigger clause, reference depth. Use when the user asks to write a new skill, review this skill, lint a SKILL.md, check skill frontmatter, or after editing any file under a skills//SKILL.md path.
Drive one vertical slice of behaviour red-green-refactor, seam agreed before the first test. Use when the user asks to add a feature, fix a bug, write code test-first, says "TDD this", "red green refactor", or "write a failing test first". Inside a live dossier:build covenant, invoke dossier:build instead — it…
Check the column budget of the lines a change adds, and read that change against the TIGERSTYLE shape rules a script cannot judge. Use when the user asks about line length or column limits, to check code shape, what the column check flagged, or why a commit was blocked on a column budget.