Resolves the GPT-4.1 cross-review FIX items on the §3.3.2 CI apply/verify guard:
- Symlink-escape (Medium-High): reject any candidate diff that introduces a
symlink (git mode 120000). A symlink can redirect a later in-diff write into a
denied path that textual canonicalization cannot see; auto-built diffs have no
legitimate symlinks, so this fails closed (exit 7).
- Diff-parse robustness (Medium): decode the diff as strict UTF-8 and fail closed
(exit 8) instead of errors='replace', closing homoglyph/encoding evasion.
- Declared-scope canonicalization (Medium): drop parent-escaping scope globs so a
malformed scope can only shrink coverage, never widen it past repo root.
- Egress allowlist (Low-Med): explicit DEPLOY marker to parameterize the
build-test registries per target repo before enabling.
Backs the gate's correctness claim with a committed, runnable suite
(tests/test_ci_gate_workflow.py) that extracts the inline guard from the YAML and
exercises good + adversarial diffs (clean, hash mismatch, workflow delete,
copy-into-denied, symlink, non-UTF-8, out-of-scope, unscoped, escaping scope).
Corrects the README "Tests" section that claimed coverage that did not exist.
Full suite: 557 passed, 1 skipped; ruff clean.
