refactor(pchome): extract evidence enrichment

tests/test_pchome_mapping_backlog_modularization.py

@@ -7,6 +7,7 @@ from services.pchome_mapping_backlog import (
     controlled_apply_executor,
     controlled_apply_receipt,
     controlled_apply_verifier,
+    enrichment,
     evidence,
     policies,
     reporter,
@@ -201,7 +202,50 @@ def test_reporter_keeps_legacy_identity_and_read_only_preview():
     assert preview["safety"]["writes_database"] is False
 
 
-def test_legacy_facade_is_smaller_after_fifth_p0_extraction():
+def test_enrichment_keeps_legacy_identity_and_no_write_preview():
+    assert (
+        compatibility_facade.build_pchome_evidence_enrichment_preview
+        is enrichment.build_pchome_evidence_enrichment_preview
+    )
+    assert (
+        compatibility_facade.build_pchome_evidence_source_preview
+        is enrichment.build_pchome_evidence_source_preview
+    )
+    assert (
+        compatibility_facade._build_evidence_task
+        is enrichment._build_evidence_task
+    )
+    assert (
+        compatibility_facade._build_fetch_gate_candidates
+        is enrichment._build_fetch_gate_candidates
+    )
+    assert (
+        compatibility_facade._field_enrichment_sources
+        is enrichment._field_enrichment_sources
+    )
+    assert (
+        compatibility_facade._source_plan_for_field
+        is enrichment._source_plan_for_field
+    )
+
+    payload = {
+        "success": True,
+        "generated_at": "2026-07-11T15:30:00+08:00",
+        "stats": {},
+        "opportunities": [],
+    }
+    preview = enrichment.build_pchome_evidence_enrichment_preview(payload)
+    source_preview = enrichment.build_pchome_evidence_source_preview(payload)
+
+    assert preview["result"] == "NO_TARGETS"
+    assert source_preview["result"] == "NO_TARGETS"
+    assert preview["safety"]["fetches_external_sites"] is False
+    assert preview["safety"]["writes_database"] is False
+    assert source_preview["safety"]["fetches_external_sites"] is False
+    assert source_preview["safety"]["writes_database"] is False
+
+
+def test_legacy_facade_is_smaller_after_sixth_p0_extraction():
     facade = ROOT / "services/pchome_mapping_backlog_service.py"
 
-    assert sum(1 for _ in facade.open(encoding="utf-8")) < 43_200
+    assert sum(1 for _ in facade.open(encoding="utf-8")) < 42_900