fix: harden task3 qdrant compatibility boundaries

harness/tests/test_registry_evidence_config.py

@@ -460,7 +460,7 @@ def test_registry_rendered_session_and_maintenance_configs_require_existing_qdra
     assert yaml.safe_load(maintenance_path.read_text())["vectors"]["collection_lifecycle"] == "require_existing"
     assert session_path.read_bytes() == maintenance_path.read_bytes()
 
-    from test_qdrant_vector_store import FakeQdrantHttp, _write_record
+    from qdrant_test_helpers import FakeQdrantHttp, _write_record
 
     for cfg in (session_cfg, maintenance_cfg):
         fake = FakeQdrantHttp(dimension=384) if collection_state == "incompatible" else FakeQdrantHttp()
@@ -481,6 +481,40 @@ def test_registry_rendered_session_and_maintenance_configs_bind_equally(tmp_path
     )
 
 
+def test_loader_rejects_split_brain_qdrant_compatibility_resources(tmp_path):
+    values = _qdrant_config_yaml(tmp_path, registry=True)
+    values["vectors"]["collection"] = "workspace-a"
+    values["resources"] = {
+        "vector": {
+            "engine": "qdrant",
+            "base_url": "http://qdrant:6333/",
+            "collection": "workspace-b",
+        }
+    }
+    path = tmp_path / "split-brain.yaml"
+    path.write_text(yaml.safe_dump(values))
+
+    with pytest.raises(ConfigError, match="vectors.*resources.vector|disagree"):
+        load_config(path)
+
+
+def test_loader_rejects_lifecycle_policy_in_compatibility_resource(tmp_path):
+    values = _qdrant_config_yaml(tmp_path, registry=True)
+    values["resources"] = {
+        "vector": {
+            "engine": "qdrant",
+            "base_url": "http://qdrant:6333",
+            "collection": "workspace-semantic",
+            "collection_lifecycle": "require_existing",
+        }
+    }
+    path = tmp_path / "lifecycle.yaml"
+    path.write_text(yaml.safe_dump(values))
+
+    with pytest.raises(ConfigError, match="collection_lifecycle"):
+        load_config(path)
+
+
 def test_legacy_runtime_config_keeps_create_capable_qdrant_default(tmp_path):
     path = tmp_path / "legacy.yaml"
     path.write_text(yaml.safe_dump(_qdrant_config_yaml(tmp_path, registry=False)))