Every issue class found gets a mechanical guard

“About the issues you found, ensure these types of issues cannot re-occur in the future” (user, 2026-10-07). Every CLASS of issue found — not only the instance — becomes mechanically impossible (a typed API, a schema, a refusal at a door) or is caught automatically at the lowest choke point (the commit hooks, harness check, the merge door, a test). Reviewer vigilance is not a guard.

• Each guard proves itself: a planted violation it must catch (in more than one place) and a near-miss it must not flag (UR-20).
• A guard’s existing debt is a burn-down list that only shrinks, each entry owned by a task (UR-19); a genuine false positive is fixed in the guard, never exempted one key at a time.
• A verifier names the class of each finding, or proposes a new class; a class without a guard is a queue item.