fix(evidence): isolate vectors by workspace

harness/tests/l0/test_pgvector_store.py

@@ -130,14 +130,29 @@ def test_pgvector_lists_and_deletes_exact_evidence_generation(store):
     value = VectorWriteRecord(
         record=VectorRecord(
             id="evidence-generation-a", kind="evidence", ref="doc:a", title="a",
-            content="content", metadata={"vector_generation": generation},
+            content="content", metadata={"vector_generation": generation, "workspace_id": "default"},
         ),
         embedding=[1.0, 0.0], content_hash="sha256:" + "a" * 64,
     )
     store.upsert("evidence", [value])
-    assert generation in store.list_evidence_generations("evidence")
-    assert store.delete_generation("evidence", generation) == 1
-    assert generation not in store.list_evidence_generations("evidence")
+    assert generation in store.list_evidence_generations("evidence", "default")
+    assert store.delete_generation("evidence", generation, "default") == 1
+    assert generation not in store.list_evidence_generations("evidence", "default")
+
+
+def test_pgvector_generation_cleanup_isolated_between_workspaces(store):
+    generation = "gen:" + "b" * 32
+    records = [VectorWriteRecord(
+        record=VectorRecord(
+            id=f"evidence-{workspace}", kind="evidence", ref=f"doc:{workspace}",
+            title=workspace, content=workspace,
+            metadata={"vector_generation": generation, "workspace_id": workspace},
+        ), embedding=[1.0, 0.0], content_hash="sha256:" + key * 64,
+    ) for workspace, key in (("workspace-a", "b"), ("workspace-b", "c"))]
+    store.upsert("evidence", records)
+    assert store.delete_generation("evidence", generation, "workspace-a") == 1
+    assert generation not in store.list_evidence_generations("evidence", "workspace-a")
+    assert generation in store.list_evidence_generations("evidence", "workspace-b")
 
 
 def test_pgvector_search_filters_kinds_before_limit(store):