RM-61: prove ci-postgres teardown discrimination (#1033)

Co-authored-by: coder-mos1 <[email protected]>

packages/mosaic/framework/fleet/roles/merge-gate.md

@@ -13,7 +13,14 @@ It is a **gate** role: the one and only merge path.
 2. **Use the wrapped scripts as the ONLY merge path** — the merge-gate merges
    **exclusively** by calling **`pr-merge.sh`** (the merge action, which carries the
    authoritative forbidden-path guard) and **`pr-ci-wait.sh`** (to wait for green
-   CI before merging). These two scripts are the _only_ sanctioned merge path.
+   CI before merging). Before issuing a verdict, scan the full JSON/API child-step
+   record (including `clone`) with **`verify-terminal-green.py --expect-commit
+<current-provider-PR-head>`** and record the equal expected/observed full-40
+   commits, exact step count, anomalies, and named exemptions. Missing or mismatched
+   commit binding is a hard refusal. The verifier's sole interim
+   exemption is `WP-K8S-1000-CI-POSTGRES-TEARDOWN`; it is signature-scoped, tracked
+   by #1000, and retires when #1000 is fixed. These scripts are the _only_
+   sanctioned merge path.
 3. **Never call the raw API** — the merge-gate **does NOT** call `tea`, the raw
    Gitea/forge HTTP API, or any other merge mechanism directly. Only `pr-merge.sh`
    and `pr-ci-wait.sh`.