feat(#85): IMP catalog builder invariant + VP runtime gate (u1~u7)

- u1: BuilderMissingError(FitError) — narrow exception aligned with pipeline catch
- u2: load_frame_contracts catalog invariant + VP skip + CatalogInvariantError
- u3a: audit CLI I1~I3 (partial existence / declared builder / registry membership)
- u3b: audit CLI I4 (slot_payload refs vs declared/generated payload keys)
- u4: lookup_v4_candidates VP filter (lookup_v4_all_judgments raw telemetry untouched)
- u5: catalog invariant regression coverage + temp non-VP failure fixtures
- u6: mdx04 VP routing fixture tests (sw_dependency_four_problems excluded from live)
- u7: tests/conftest.py env isolation + mdx03/mdx04/mdx05 subprocess smoke

Targeted 74 PASS (12.31s). Full regression 1063 PASS (87.70s). Audit CLI clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_catalog_invariant.py

@@ -79,3 +79,149 @@ def test_catalog_entry_count_matches_frame_count():
         f"catalog shape inconsistent: entries={entry_count} "
         f"templates={template_count} frames={frame_count}"
     )
+
+
+# ──────────────────────── IMP-#85 u5 regression coverage ────────────────────────
+#
+# Scope (Stage 2 lock):
+#   - Prod catalog passes the audit CLI (run_audit) end-to-end.
+#   - Non-VP fixture catalogs reproduce the boot invariant (u2) + audit (u3a/u3b)
+#     negative paths: missing payload.builder, missing partial, undeclared
+#     slot_payload reference (I4 generated-key-orphan).
+#   - Same fixtures with `visual_pending: true` MUST be silently skipped — the
+#     data-driven VP scope guard from u2/u3a/u3b must not regress.
+#
+# Out of scope:
+#   - Implementing the 17 missing VP builders (별 P0 / IMP-04b backlog).
+#   - Visual rendering of fixture frames.
+#
+# Path-convention note (tests/CLAUDE.md §F-5):
+#   Stage 2 plan named `tests/fixtures/catalog/` but the project convention
+#   reserves the root `tests/fixtures/` for non-Phase-Z fixtures (creation
+#   requires a separate issue). Phase-Z YAML fixtures live under
+#   `tests/phase_z2/fixtures/`. The u5 fixtures therefore live at
+#   `tests/phase_z2/fixtures/catalog/`.
+
+import yaml
+
+from scripts.audit_frame_invariants import (
+    DEFAULT_CATALOG_PATH,
+    DEFAULT_PARTIALS_DIR,
+    run_audit,
+)
+from src import phase_z2_mapper
+from src.phase_z2_mapper import (
+    CatalogInvariantError,
+    PAYLOAD_BUILDERS,
+    _check_catalog_builder_invariant,
+)
+
+_IMP85_FIXTURES_DIR = Path(__file__).parent / "phase_z2" / "fixtures" / "catalog"
+_MISSING_BUILDER_FIXTURE = _IMP85_FIXTURES_DIR / "missing_builder_non_vp.yaml"
+_UNDECLARED_SLOT_FIXTURE = _IMP85_FIXTURES_DIR / "undeclared_slot_ref_non_vp.yaml"
+
+
+def _load_fixture_catalog(path: Path) -> dict:
+    with path.open(encoding="utf-8") as f:
+        return yaml.safe_load(f)
+
+
+@pytest.fixture
+def _reset_catalog_cache_for_imp85():
+    """Some tests below load fixture YAMLs into the boot invariant; ensure the
+    prod cache is untouched on entry/exit so other tests stay deterministic."""
+    phase_z2_mapper._CATALOG_CACHE = None
+    yield
+    phase_z2_mapper._CATALOG_CACHE = None
+
+
+def test_prod_catalog_audit_clean():
+    """IMP-#85 u5 — prod catalog + prod partials dir pass audit (I1-I4 clean)."""
+    violations = run_audit(DEFAULT_CATALOG_PATH, DEFAULT_PARTIALS_DIR)
+    assert violations == [], (
+        f"Prod catalog audit reported {len(violations)} violation(s):\n  - "
+        + "\n  - ".join(violations)
+    )
+
+
+def test_missing_builder_fixture_raises_catalog_invariant(
+    _reset_catalog_cache_for_imp85,
+):
+    """Fixture: non-VP contract with unregistered builder → u2 invariant raise."""
+    catalog = _load_fixture_catalog(_MISSING_BUILDER_FIXTURE)
+    with pytest.raises(CatalogInvariantError) as exc:
+        _check_catalog_builder_invariant(catalog)
+    msg = str(exc.value)
+    assert "imp85_u5_missing_builder_frame" in msg
+    assert "definitely_not_a_registered_builder_imp85_u5" in msg
+
+
+def test_missing_builder_fixture_audit_reports_i3(tmp_path):
+    """Fixture: non-VP contract with unregistered builder → audit I3 + I1.
+
+    The fixture frame's template_id has no partial on disk (tmp_path is empty),
+    so I1 fires as well. I3 is the primary assertion target; I1 surfacing is
+    expected and asserted to lock both audit paths together.
+    """
+    violations = run_audit(_MISSING_BUILDER_FIXTURE, tmp_path)
+    joined = "\n".join(violations)
+    assert any(
+        v.startswith("I3 builder-unregistered:")
+        and "imp85_u5_missing_builder_frame" in v
+        for v in violations
+    ), f"expected I3 builder-unregistered violation, got:\n{joined}"
+    assert any(
+        v.startswith("I1 partial-missing:")
+        and "imp85_u5_missing_builder_frame" in v
+        for v in violations
+    ), f"expected I1 partial-missing violation, got:\n{joined}"
+
+
+def test_undeclared_slot_fixture_audit_reports_i4(tmp_path):
+    """Fixture: non-VP contract with valid builder but orphan generated key.
+
+    `items_with_role` + `array_root: orphan_array_root_imp85_u5` produces
+    `slot_payload.orphan_array_root_imp85_u5`. The temp partial below contains
+    `slot_payload.title` only (no bracket access), so I4 must fire on the
+    orphan array_root key.
+    """
+    partials_dir = tmp_path / "families"
+    partials_dir.mkdir()
+    partial = partials_dir / "imp85_u5_undeclared_slot_frame.html"
+    partial.write_text(
+        "<div>{{ slot_payload.title }}</div>",
+        encoding="utf-8",
+    )
+
+    violations = run_audit(_UNDECLARED_SLOT_FIXTURE, partials_dir)
+    joined = "\n".join(violations)
+    assert any(
+        v.startswith("I4 generated-key-orphan:")
+        and "imp85_u5_undeclared_slot_frame" in v
+        and "orphan_array_root_imp85_u5" in v
+        for v in violations
+    ), f"expected I4 generated-key-orphan violation, got:\n{joined}"
+
+
+def test_fixtures_with_visual_pending_true_are_skipped(
+    tmp_path, _reset_catalog_cache_for_imp85,
+):
+    """VP scope guard — flipping `visual_pending: true` on fixture frames must
+    silence both the boot invariant (u2) and the audit CLI (I1-I4)."""
+    missing = _load_fixture_catalog(_MISSING_BUILDER_FIXTURE)
+    undeclared = _load_fixture_catalog(_UNDECLARED_SLOT_FIXTURE)
+    for entry in (*missing.values(), *undeclared.values()):
+        entry["visual_pending"] = True
+
+    _check_catalog_builder_invariant(missing)
+    _check_catalog_builder_invariant(undeclared)
+
+    vp_yaml = tmp_path / "vp_only.yaml"
+    vp_yaml.write_text(yaml.safe_dump({**missing, **undeclared}), encoding="utf-8")
+    partials_dir = tmp_path / "families"
+    partials_dir.mkdir()
+    violations = run_audit(vp_yaml, partials_dir)
+    assert violations == [], (
+        f"VP frames must be silently skipped, got:\n  - "
+        + "\n  - ".join(violations)
+    )