Phase-2 prerequisite: integration test for blocking-mode submit-only→exit-2 path with real metadata

[michael-wojcik]

Context

Surfaced during PR #477 round-8 blind review by round8-tester. Task #89 / review round 8, #401 teachback gate.

Finding (HIGH, Phase-2 scope)

The existing TestMainBlockingMode test suite mocks _check_tool_allowed, so the end-to-end path of:

submit-only teachback_submit → real scanner → classify → template → exit-2 block

is NOT integration-tested with real metadata. The unit-level pieces are well-covered, but the full pipeline under _TEACHBACK_MODE = "blocking" has no integration assertion.

Matters for: issue #481 Phase-2 flip. Before flipping advisory → blocking, this integration test must exist or the first real-world blocking-mode call could trip a latent state-machine bug that structure-only unit tests wouldn't catch.

Proposal

Add test_blocking_submit_only_real_scan_exits_2 to pact-plugin/tests/test_teachback_gate.py as a Phase-2 prerequisite.

• Mode: _TEACHBACK_MODE = "blocking" (monkeypatch)
• Input: a task with teachback_submit metadata but no teachback_approved
• Assert: scanner runs for real (not mocked), classifier produces awaiting-approval reason_code, template renders the blocking-mode denial, hook exits with code 2

Non-goals

• Not a merge blocker for PR feat(#401): variety-tiered teachback gate with generation-shaped content validation #477 in advisory mode.
• Not a replacement for the existing unit tests — additive integration coverage.

Background

• PR feat(#401): variety-tiered teachback gate with generation-shaped content validation #477: teachback gate advisory mode ship
• Phase 2: flip teachback_gate to blocking mode (follow-up to #401) #481: Phase-2 flip criterion
• Wire Phase 2 readiness check into secretary wrap-up/pause flow (supports #481) #482: readiness surfacing during wrap-up (closed YAGNI)
• round-8 review HANDOFF on task feat(refresh): make confidence weights configurable #89

Priority: HIGH for Phase-2, not urgent.