Ratchet, not big bang

The rule. A new gate arms immediately against a frozen baseline of the violations that exist on the day it lands; the baseline may only shrink. Never delay arming a gate until the corpus it checks is clean.

Why. Gates that wait on cleanup never arm, and cleanup without a gate re-drifts — the brief's dedicated issue-drain pass demonstrably re-drifted the same day it ran. A baseline ratchet decouples the two: new violations fail from day one while the inherited debt burns down on its own schedule, and the shrinking baseline is itself a visible progress measure. A sibling project runs its architectural-invariant lints exactly this way, freezing existing violations in a committed baseline diff.

Bounds.

• The baseline is committed and reviewed like any other artefact; silently regenerating it to admit a new violation defeats the ratchet.
• A baseline entry is debt, not permission: each one should trace to an issue or intent that retires it.

Promotion. Adopting baseline support in record-lint (or any gate) makes this mechanical for that gate; the principle graduates per-gate as baselines become checked artefacts.