refactor(pchome): extract controlled drift verifier

tests/test_pchome_mapping_backlog_modularization.py

@@ -5,6 +5,7 @@ from services.pchome_mapping_backlog import (
     artifacts,
     contracts,
     controlled_apply_executor,
+    controlled_apply_verifier,
     evidence,
     policies,
 )
@@ -95,7 +96,46 @@ def test_controlled_apply_executor_core_is_no_write_without_apply_request(tmp_pa
     assert result["safety"]["writes_artifact_count"] == 0
 
 
-def test_legacy_facade_is_smaller_after_second_p0_extraction():
+def test_controlled_apply_drift_verifier_core_is_no_write(tmp_path):
+    replay = {
+        "result": "DIRECT_MAPPING_RETRY_EXCEPTION_CONTROLLED_APPLY_RECEIPT_REPLAYED",
+        "summary": {
+            "target_selector_count": 1,
+            "post_apply_readback_count": 1,
+            "post_apply_readback_pass_count": 1,
+            "executor_receipt_hash_match_count": 1,
+            "missing_artifact_count": 0,
+        },
+        "post_apply_readbacks": [
+            {
+                "selector_id": "selector-1",
+                "momo_icode": "MOMO-1",
+                "expected_pchome_id": "PCH-1",
+                "actual_pchome_id": "PCH-1",
+                "passed": True,
+                "writes_database": False,
+            }
+        ],
+        "receipt_replay": {"run_id": "run-1"},
+        "missing_artifacts": [],
+    }
+
+    result = controlled_apply_verifier.build_controlled_apply_drift_verifier_from_replay(
+        replay,
+        root=tmp_path,
+        source_receipt_replay=replay,
+    )
+
+    assert result["result"] == "DIRECT_MAPPING_RETRY_EXCEPTION_CONTROLLED_APPLY_DRIFT_VERIFIED"
+    assert result["success"] is True
+    assert result["summary"]["drift_count"] == 0
+    assert result["summary"]["drift_verified_count"] == 1
+    assert result["all_checks_passed"] is True
+    assert result["safety"]["writes_database_count"] == 0
+    assert result["safety"]["writes_artifact_count"] == 0
+
+
+def test_legacy_facade_is_smaller_after_third_p0_extraction():
     facade = ROOT / "services/pchome_mapping_backlog_service.py"
 
-    assert sum(1 for _ in facade.open(encoding="utf-8")) < 44_000
+    assert sum(1 for _ in facade.open(encoding="utf-8")) < 43_850