CodexHost non-patch-tool defensive fallback branch is untested

Codex multi-host support (ADR-0011). Code under review is on branch feat/codex-support-m0, not main. ca-codex ships BETA; these are blocking-severity for the affected code but nothing is merged to the default branch yet.

Severity: low | Confidence: 0.75 | Group: fallback-branch-untested

Where:

• plugins/ca-codex/hooks/_host.py:243-247
• .github/scripts/test_codex_adapter.py:252-260

Evidence / impact:

• (coverage-002) CodexHost.iter_file_ops has TWO separate 'defer to super().iter_file_ops()' defensive branches: one inside if tool in self._PATCH_TOOLS: (_host.py:240-241, exercised by test_claude_shaped_fallback at test_codex_adapter.py:252-260, which passes tool_name='Write' — a member of _PATCH_TOOLS), and a SECOND, distinct one for tools NOT in _PATCH_TOOLS (_host.py:243-247: 'Non-write tools carry no file
• (coverage-002 impact) Low likelihood (mcp tools rarely carry file_path) but this is the second of two structurally-similar fallback branches guarding against an unhandled-but-file-shaped payload reaching disk unguarded; only one of the two is verified to actually route to the base guarded-write mapping instead of silentl

Recommendation:

Add a fixture for CodexHost.iter_file_ops' non-patch-tool fallback (an mcp__*/OTHER payload carrying file_path).

Acceptance criteria:

• A test exercises the _host.py:243-247 branch.