diff --git a/.superpowers/sdd/evidence-task-5c-report.md b/.superpowers/sdd/evidence-task-5c-report.md
index 45f3c021..9bcd4282 100644
--- a/.superpowers/sdd/evidence-task-5c-report.md
+++ b/.superpowers/sdd/evidence-task-5c-report.md
@@ -102,3 +102,23 @@ JobRunner tests.
 
 Focused default/mixed/no-ACTIVE/search-pack tests pass, the real Docker pgvector lifecycle passes,
 and the final full harness plus scoped Ruff/diff invocation completed with exit code 0.
+
+## Workspace-scoped Evidence isolation
+
+- Evidence manifests, vector metadata, and record keys now carry the stable JobRunner workspace id
+  derived from the configured workspace identity (config stem), never credentials or absolute paths.
+- Every ACTIVE server-side predicate includes `workspace_id`. Legacy unscoped rows therefore fail
+  closed and cannot appear in Evidence results.
+- Vector generation inventory and deletion require the workspace namespace across the port, direct
+  pgvector adapter, HTTP client/adapter, and allowlisted RPC SQL. Legacy unscoped RPC overloads are
+  explicitly dropped during migration; destructive SQL matches collection, kind, generation, and
+  workspace together.
+- GC recovers the persisted namespace from ACTIVE for explicit/restarted cleanup and can only list
+  or delete that workspace's generations. Real shared-pgvector coverage proves deleting a generation
+  for workspace A preserves the same generation in workspace B.
+- `PipelineResult.model_dump` now serializes fields explicitly instead of `dataclasses.asdict`,
+  avoiding deepcopy of immutable `FrozenDict` metadata while preserving pristine JSON CLI output.
+
+Final focused verification: `89 passed` across corpus/CLI JSON, direct/HTTP parity, migrations, and
+real Docker pgvector lifecycle; scoped Ruff and `git diff --check` clean. A contemporaneous full-suite
+run reached unrelated Task 6 immutable-file tamper tests; those files were deliberately not changed.
diff --git a/harness/scripts/create_vector_reader_rpc.sql b/harness/scripts/create_vector_reader_rpc.sql
index 43c4ba31..08897921 100644
--- a/harness/scripts/create_vector_reader_rpc.sql
+++ b/harness/scripts/create_vector_reader_rpc.sql
@@ -43,7 +43,8 @@ begin
     table_name <> 'evidence'
     or not (metadata_filter ? 'vector_generation')
     or not (metadata_filter ? 'document_ids')
-    or jsonb_object_length(metadata_filter) <> 2
+    or not (metadata_filter ? 'workspace_id')
+    or jsonb_object_length(metadata_filter) <> 3
     or jsonb_typeof(metadata_filter->'document_ids') <> 'array'
   ) then
     raise exception 'invalid Evidence metadata filter';
@@ -56,6 +57,7 @@ begin
      where ($3 is null or t.kind = any ($3))
        and ($4 is null or (
          t.metadata->>''vector_generation'' = $4->>''vector_generation''
+         and t.metadata->>''workspace_id'' = $4->>''workspace_id''
          and t.metadata->>''document_id'' in (
            select jsonb_array_elements_text($4->''document_ids'')
          )
diff --git a/harness/scripts/create_vector_writer_rpc.sql b/harness/scripts/create_vector_writer_rpc.sql
index d006ac5e..538e215b 100644
--- a/harness/scripts/create_vector_writer_rpc.sql
+++ b/harness/scripts/create_vector_writer_rpc.sql
@@ -40,14 +40,18 @@ begin
 end;
 $$;
 
-create or replace function public.list_evidence_generations(table_name text, kind text)
+drop function if exists public.list_evidence_generations(text, text);
+
+create or replace function public.list_evidence_generations(
+  table_name text, kind text, workspace_id text
+)
 returns table(generation text)
 language plpgsql
 security definer
 set search_path = public, vectors, extensions
 as $$
 begin
-  if table_name <> 'evidence' or kind <> 'evidence' then
+  if table_name <> 'evidence' or kind <> 'evidence' or workspace_id !~ '^[a-z][a-z0-9_-]{0,63}$' then
     raise exception 'only exact Evidence generations may be listed';
   end if;
   return query
@@ -55,6 +59,7 @@ begin
       from vectors.evidence e
      where e.kind = 'evidence'
        and e.metadata->>'vector_generation' ~ '^gen:[0-9a-f]{32}$'
+       and e.metadata->>'workspace_id' = workspace_id
      order by 1;
 end;
 $$;
@@ -120,8 +125,10 @@ begin
 end;
 $$;
 
+drop function if exists public.delete_vector_generation(text, text, text);
+
 create or replace function public.delete_vector_generation(
-  table_name text, kind text, generation text
+  table_name text, kind text, generation text, workspace_id text
 )
 returns jsonb
 language plpgsql
@@ -130,11 +137,13 @@ set search_path = public, vectors, extensions
 as $$
 declare affected integer;
 begin
-  if table_name <> 'evidence' or kind <> 'evidence' or generation !~ '^gen:[0-9a-f]{32}$' then
+  if table_name <> 'evidence' or kind <> 'evidence' or generation !~ '^gen:[0-9a-f]{32}$'
+     or workspace_id !~ '^[a-z][a-z0-9_-]{0,63}$' then
     raise exception 'only an exact Evidence generation may be deleted';
   end if;
   delete from vectors.evidence e
-   where e.kind = 'evidence' and e.metadata->>'vector_generation' = generation;
+   where e.kind = 'evidence' and e.metadata->>'vector_generation' = generation
+     and e.metadata->>'workspace_id' = workspace_id;
   get diagnostics affected = row_count;
   return jsonb_build_object('deleted', affected);
 end;
@@ -143,8 +152,8 @@ $$;
 revoke all on function public._assert_vector_write_table(text, text[]) from public;
 revoke all on function public.existing_vector_hashes(text, text[]) from public;
 revoke all on function public.upsert_vector_records(text, jsonb) from public;
-revoke all on function public.delete_vector_generation(text, text, text) from public;
-revoke all on function public.list_evidence_generations(text, text) from public;
+revoke all on function public.delete_vector_generation(text, text, text, text) from public;
+revoke all on function public.list_evidence_generations(text, text, text) from public;
 
 -- Su alcuni progetti Supabase le funzioni in `public` ricevono grant automatici: revoca
 -- esplicitamente dai ruoli client generici, poi abilita solo il writer dedicato.
@@ -153,20 +162,20 @@ begin
   if exists (select 1 from pg_roles where rolname = 'anon') then
     revoke all on function public.existing_vector_hashes(text, text[]) from anon;
     revoke all on function public.upsert_vector_records(text, jsonb) from anon;
-    revoke all on function public.delete_vector_generation(text, text, text) from anon;
-    revoke all on function public.list_evidence_generations(text, text) from anon;
+    revoke all on function public.delete_vector_generation(text, text, text, text) from anon;
+    revoke all on function public.list_evidence_generations(text, text, text) from anon;
   end if;
   if exists (select 1 from pg_roles where rolname = 'authenticated') then
     revoke all on function public.existing_vector_hashes(text, text[]) from authenticated;
     revoke all on function public.upsert_vector_records(text, jsonb) from authenticated;
-    revoke all on function public.delete_vector_generation(text, text, text) from authenticated;
-    revoke all on function public.list_evidence_generations(text, text) from authenticated;
+    revoke all on function public.delete_vector_generation(text, text, text, text) from authenticated;
+    revoke all on function public.list_evidence_generations(text, text, text) from authenticated;
   end if;
   if exists (select 1 from pg_roles where rolname = 'vector_writer') then
     grant execute on function public.existing_vector_hashes(text, text[]) to vector_writer;
     grant execute on function public.upsert_vector_records(text, jsonb) to vector_writer;
-    grant execute on function public.delete_vector_generation(text, text, text) to vector_writer;
-    grant execute on function public.list_evidence_generations(text, text) to vector_writer;
+    grant execute on function public.delete_vector_generation(text, text, text, text) to vector_writer;
+    grant execute on function public.list_evidence_generations(text, text, text) to vector_writer;
   end if;
 end $$;
 
diff --git a/harness/tests/l0/test_pgvector_corpus_lifecycle.py b/harness/tests/l0/test_pgvector_corpus_lifecycle.py
index bc988a32..9a06bc29 100644
--- a/harness/tests/l0/test_pgvector_corpus_lifecycle.py
+++ b/harness/tests/l0/test_pgvector_corpus_lifecycle.py
@@ -241,7 +241,8 @@ def test_real_pgvector_corpus_job_lifecycle(tmp_path, persistent_pgvector):
         record=VectorRecord(
             id="chunk:exact-vector-orphan", kind="evidence", ref="doc:orphan",
             title="orphan", content="orphan",
-            metadata={"document_id": "doc:orphan", "vector_generation": orphan},
+                metadata={"document_id": "doc:orphan", "vector_generation": orphan,
+                          "workspace_id": "pgvector-lifecycle"},
         ),
         embedding=query, content_hash="sha256:" + "f" * 64,
     )])
@@ -251,5 +252,7 @@ def test_real_pgvector_corpus_job_lifecycle(tmp_path, persistent_pgvector):
     expected_fs = set(generations[-2:])
     assert set(CorpusStore(tmp_path / "corpus").list_generations()) == expected_fs
     expected_vectors = expected_fs | {generations[0]}
-    assert set(recreated.list_evidence_generations("evidence")) == expected_vectors
+    assert set(recreated.list_evidence_generations(
+        "evidence", "pgvector-lifecycle"
+    )) == expected_vectors
     assert final_pipeline.gc(workspace_root=tmp_path)["evicted"] == []
diff --git a/harness/tests/l0/test_pgvector_store.py b/harness/tests/l0/test_pgvector_store.py
index d01b3a3a..83c77b66 100644
--- a/harness/tests/l0/test_pgvector_store.py
+++ b/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):
diff --git a/harness/tests/l0/test_vector_adapter_parity.py b/harness/tests/l0/test_vector_adapter_parity.py
index 41fe3a93..ec5899ad 100644
--- a/harness/tests/l0/test_vector_adapter_parity.py
+++ b/harness/tests/l0/test_vector_adapter_parity.py
@@ -235,9 +235,10 @@ def test_http_delete_generation_uses_exact_allowlisted_rpc_payload(monkeypatch):
         lambda url, json, **kwargs: calls.append((url, json)) or Response({"deleted": 2}),
     )
     client = VectorRestClient(RestConfig(base_url="https://vectors.test", api_key="writer"))
-    assert client.delete_generation("evidence", "gen:" + "a" * 32) == 2
+    assert client.delete_generation("evidence", "gen:" + "a" * 32, "default") == 2
     assert calls == [("https://vectors.test/rpc/delete_vector_generation", {
         "table_name": "evidence", "kind": "evidence", "generation": "gen:" + "a" * 32,
+        "workspace_id": "default",
     })]
 
 
@@ -248,7 +249,7 @@ def test_http_delete_generation_legacy_404_fails_closed_without_body_leak(monkey
     )
     client = VectorRestClient(RestConfig(base_url="https://vectors.test", api_key="writer"))
     with pytest.raises(VectorRestError, match="delete_vector_generation RPC is unavailable") as error:
-        client.delete_generation("evidence", "gen:" + "a" * 32)
+        client.delete_generation("evidence", "gen:" + "a" * 32, "default")
     assert "secret" not in str(error.value)
 
 
@@ -261,9 +262,9 @@ def test_http_list_evidence_generations_exact_rpc_and_legacy_fail_closed(monkeyp
         ]),
     )
     client = VectorRestClient(RestConfig(base_url="https://vectors.test", api_key="writer"))
-    assert client.list_evidence_generations("evidence") == ["gen:" + "a" * 32]
+    assert client.list_evidence_generations("evidence", "default") == ["gen:" + "a" * 32]
     assert calls[0][0].endswith("/rpc/list_evidence_generations")
-    assert calls[0][1] == {"table_name": "evidence", "kind": "evidence"}
+    assert calls[0][1] == {"table_name": "evidence", "kind": "evidence", "workspace_id": "default"}
 
 
 @pytest.mark.parametrize("generation", ["gen:a", "gen:" + "A" * 32, "gen:" + "a" * 33])
@@ -274,7 +275,7 @@ def test_http_generation_operations_reject_noncanonical_values(monkeypatch, gene
     )
     client = VectorRestClient(RestConfig(base_url="https://vectors.test", api_key="writer"))
     with pytest.raises(ValueError, match="canonical"):
-        client.delete_generation("evidence", generation)
+            client.delete_generation("evidence", generation, "default")
 
 
 def test_http_inventory_rejects_malformed_rpc_output(monkeypatch):
@@ -284,4 +285,4 @@ def test_http_inventory_rejects_malformed_rpc_output(monkeypatch):
     )
     client = VectorRestClient(RestConfig(base_url="https://vectors.test", api_key="writer"))
     with pytest.raises(VectorRestError, match="malformed"):
-        client.list_evidence_generations("evidence")
+        client.list_evidence_generations("evidence", "default")
diff --git a/harness/tests/test_corpus_pipeline.py b/harness/tests/test_corpus_pipeline.py
index 92fb12f1..e4d067bb 100644
--- a/harness/tests/test_corpus_pipeline.py
+++ b/harness/tests/test_corpus_pipeline.py
@@ -1,7 +1,7 @@
 import pytest
 
 from tht.corpus.chunk import ChunkPolicy
-from tht.corpus.pipeline import CorpusPipeline, PipelineError
+from tht.corpus.pipeline import CorpusPipeline, PipelineError, PipelineResult
 from tht.corpus.store import CorpusStore
 from tht.corpus.models import CorpusManifest
 from tht.ports.evidence import AcquiredDocument, SourceObject
@@ -55,17 +55,19 @@ class Vectors:
             value.record.id: value.content_hash for value in self.records
         }
 
-    def delete_generation(self, collection, generation):
+    def delete_generation(self, collection, generation, workspace_id):
         self.records = [
             value for value in self.records
-            if value.record.metadata["vector_generation"] != generation
+            if not (value.record.metadata["vector_generation"] == generation
+                    and value.record.metadata.get("workspace_id") == workspace_id)
         ]
         return 0
 
-    def list_evidence_generations(self, collection):
+    def list_evidence_generations(self, collection, workspace_id):
         return sorted({
             value.record.metadata["vector_generation"] for value in self.records
             if value.record.kind == "evidence"
+            and value.record.metadata.get("workspace_id") == workspace_id
         })
 
 
@@ -128,10 +130,10 @@ def test_retention_keeps_filesystem_when_vector_purge_fails_then_retries(tmp_pat
             super().__init__()
             self.fail_delete = True
 
-        def delete_generation(self, collection, generation):
+        def delete_generation(self, collection, generation, workspace_id):
             if self.fail_delete:
                 raise RuntimeError("credential secret")
-            return super().delete_generation(collection, generation)
+            return super().delete_generation(collection, generation, workspace_id)
 
     vectors = FailingDelete()
     for index in range(2):
@@ -156,13 +158,13 @@ def test_gc_reconciles_vector_only_generation(tmp_path):
     from tht.vectorstore.records import VectorRecord
     vectors.records.append(VectorWriteRecord(
         record=VectorRecord(id="orphan", kind="evidence", ref="doc:x", title="", content="x",
-                            metadata={"vector_generation": orphan}),
+                            metadata={"vector_generation": orphan, "workspace_id": "default"}),
         embedding=[0.0, 0.0, 0.0], content_hash="sha256:" + "0" * 64,
     ))
     candidate = pipeline(tmp_path, Source([]), vectors=vectors, retain=1)
     report = candidate.gc(workspace_root=tmp_path)
     assert report["evicted"] == [orphan]
-    assert vectors.list_evidence_generations("evidence") == []
+    assert vectors.list_evidence_generations("evidence", "default") == []
     assert candidate.gc(workspace_root=tmp_path)["evicted"] == []
 
 
@@ -233,7 +235,7 @@ def test_gc_preserves_vector_dependencies_of_retained_manifests(tmp_path):
         vectors=vectors, retain=2,
     ).run().generation
     assert CorpusStore(tmp_path / "corpus").list_generations() == [second, third]
-    assert first in vectors.list_evidence_generations("evidence")
+    assert first in vectors.list_evidence_generations("evidence", "default")
 
 
 def test_active_searcher_without_active_fails_closed_for_evidence(tmp_path):
@@ -319,6 +321,14 @@ def test_active_evidence_query_holds_lock_against_publish(tmp_path):
     assert published.is_set()
 
 
+def test_pipeline_result_dump_does_not_deepcopy_frozen_metadata():
+    manifest = CorpusManifest(metadata={"nested": {"value": ["safe"]}})
+    payload = PipelineResult(
+        "succeeded", None, False, (), (), (), manifest,
+    ).model_dump(mode="json")
+    assert payload["manifest"]["metadata"] == {"nested": {"value": ["safe"]}}
+
+
 def test_unchanged_documents_skip_acquire_normalize_chunk_and_embed(tmp_path):
     one = item("one", "a")
     first_source = Source([(one, "hello")])
diff --git a/harness/tht/adapters/vector/pgvector.py b/harness/tht/adapters/vector/pgvector.py
index 756277df..d0db7495 100644
--- a/harness/tht/adapters/vector/pgvector.py
+++ b/harness/tht/adapters/vector/pgvector.py
@@ -273,16 +273,18 @@ class PgVectorStore:
                         filter_params.append(collection_kinds)
                     if metadata_filter is not None:
                         if collection != "evidence" or set(metadata_filter) != {
-                            "vector_generation", "document_ids"
+                            "vector_generation", "document_ids", "workspace_id"
                         }:
                             raise VectorStoreError("Unsupported vector metadata filter")
                         generation = metadata_filter["vector_generation"]
                         document_ids = metadata_filter["document_ids"]
-                        if not isinstance(generation, str) or not isinstance(document_ids, list):
+                        workspace_id = metadata_filter["workspace_id"]
+                        if not isinstance(generation, str) or not isinstance(document_ids, list) or not isinstance(workspace_id, str):
                             raise VectorStoreError("Invalid vector metadata filter")
                         clauses.append(sql.SQL("metadata->>'vector_generation' = %s"))
                         clauses.append(sql.SQL("metadata->>'document_id' = ANY(%s)"))
-                        filter_params.extend((generation, document_ids))
+                        clauses.append(sql.SQL("metadata->>'workspace_id' = %s"))
+                        filter_params.extend((generation, document_ids, workspace_id))
                     where = (
                         sql.SQL(" WHERE ") + sql.SQL(" AND ").join(clauses)
                         if clauses else sql.SQL("")
@@ -404,9 +406,11 @@ class PgVectorStore:
                 raw.close()
         return len(records)
 
-    def delete_generation(self, collection: str, generation: str) -> int:
+    def delete_generation(self, collection: str, generation: str, workspace_id: str) -> int:
         if collection != "evidence" or re.fullmatch(r"gen:[0-9a-f]{32}", generation) is None:
             raise VectorStoreError("Only exact Evidence generations may be deleted")
+        if re.fullmatch(r"[a-z][a-z0-9_-]{0,63}", workspace_id) is None:
+            raise VectorStoreError("Invalid Evidence workspace namespace")
         raw = None
         try:
             raw = self._require_writer().raw_connection()
@@ -414,9 +418,10 @@ class PgVectorStore:
                 cursor.execute(
                     sql.SQL(
                         "DELETE FROM {} WHERE kind = 'evidence' "
-                        "AND metadata->>'vector_generation' = %s"
+                        "AND metadata->>'vector_generation' = %s "
+                        "AND metadata->>'workspace_id' = %s"
                     ).format(_collection(self._schema, collection)),
-                    (generation,),
+                    (generation, workspace_id),
                 )
                 count = cursor.rowcount
             raw.commit()
@@ -429,9 +434,11 @@ class PgVectorStore:
             if raw is not None:
                 raw.close()
 
-    def list_evidence_generations(self, collection: str) -> list[str]:
+    def list_evidence_generations(self, collection: str, workspace_id: str) -> list[str]:
         if collection != "evidence":
             raise VectorStoreError("Only exact Evidence generations may be listed")
+        if re.fullmatch(r"[a-z][a-z0-9_-]{0,63}", workspace_id) is None:
+            raise VectorStoreError("Invalid Evidence workspace namespace")
         raw = None
         try:
             raw = self._require_writer().raw_connection()
@@ -440,8 +447,9 @@ class PgVectorStore:
                     sql.SQL(
                         "SELECT DISTINCT metadata->>'vector_generation' FROM {} "
                         "WHERE kind = 'evidence' AND metadata->>'vector_generation' "
-                        "~ '^gen:[0-9a-f]{{32}}$' ORDER BY 1"
-                    ).format(_collection(self._schema, collection))
+                        "~ '^gen:[0-9a-f]{{32}}$' AND metadata->>'workspace_id' = %s ORDER BY 1"
+                    ).format(_collection(self._schema, collection)),
+                    (workspace_id,),
                 )
                 return [row[0] for row in cursor.fetchall()]
         except Exception as exc:
diff --git a/harness/tht/adapters/vector/thoth_http.py b/harness/tht/adapters/vector/thoth_http.py
index 4b5276b1..5a93b3c3 100644
--- a/harness/tht/adapters/vector/thoth_http.py
+++ b/harness/tht/adapters/vector/thoth_http.py
@@ -155,19 +155,19 @@ class ThothHttpVectorStore:
         except VectorRestError as exc:
             raise VectorStoreError(str(exc)) from exc
 
-    def delete_generation(self, collection: str, generation: str) -> int:
+    def delete_generation(self, collection: str, generation: str, workspace_id: str) -> int:
         if collection != "evidence" or re.fullmatch(r"gen:[0-9a-f]{32}", generation) is None:
             raise VectorStoreError("Only exact Evidence generations may be deleted")
         try:
-            return self._require_writer().delete_generation(collection, generation)
+            return self._require_writer().delete_generation(collection, generation, workspace_id)
         except VectorRestError as exc:
             raise VectorStoreError(str(exc)) from exc
 
-    def list_evidence_generations(self, collection: str) -> list[str]:
+    def list_evidence_generations(self, collection: str, workspace_id: str) -> list[str]:
         if collection != "evidence":
             raise VectorStoreError("Only exact Evidence generations may be listed")
         try:
-            return self._require_writer().list_evidence_generations(collection)
+            return self._require_writer().list_evidence_generations(collection, workspace_id)
         except VectorRestError as exc:
             raise VectorWriteUnavailable("Vector generation inventory unavailable") from exc
 
diff --git a/harness/tht/corpus/pipeline.py b/harness/tht/corpus/pipeline.py
index 4c068a7c..0a516889 100644
--- a/harness/tht/corpus/pipeline.py
+++ b/harness/tht/corpus/pipeline.py
@@ -47,9 +47,17 @@ class PipelineResult:
     resumed_from: str | None = None
 
     def model_dump(self, mode=None):
-        value = asdict(self)
-        value["manifest"] = self.manifest.model_dump(mode="json")
-        return value
+        return {
+            "status": self.status,
+            "generation": self.generation,
+            "published": self.published,
+            "changed": list(self.changed),
+            "unchanged": list(self.unchanged),
+            "removed": list(self.removed),
+            "manifest": self.manifest.model_dump(mode="json"),
+            "run_id": self.run_id,
+            "resumed_from": self.resumed_from,
+        }
 
 
 def _fingerprint(value) -> str:
@@ -62,6 +70,7 @@ class CorpusPipeline:
         self, *, store: CorpusStore, sources: list[EvidenceSource], embedder,
         vector_store: VectorStore, embedding_model: str, embedding_dimensions: int,
         chunk_policy: ChunkPolicy, pipeline_version: str, retain_published_generations: int = 3,
+        workspace_id: str = "default",
     ) -> None:
         self.store = store
         self.sources = sources
@@ -74,6 +83,7 @@ class CorpusPipeline:
         if isinstance(retain_published_generations, bool) or retain_published_generations < 1:
             raise ValueError("retain_published_generations must be at least 1")
         self.retain_published_generations = retain_published_generations
+        self.workspace_id = workspace_id
 
     def _protected_generations(self, workspace_root: Path) -> set[str]:
         protected = {value for value in (self.store.active_generation(),) if value}
@@ -92,9 +102,14 @@ class CorpusPipeline:
         return protected
 
     def gc(self, *, workspace_root: Path, dry_run: bool = False) -> dict:
+        active_manifest = self.store.active_manifest()
+        if active_manifest is not None:
+            persisted_workspace = active_manifest.metadata.get("workspace_id")
+            if isinstance(persisted_workspace, str):
+                self.workspace_id = persisted_workspace
         published = self.store.published_generations()
         list_vectors = getattr(self.vector_store, "list_evidence_generations", None)
-        vector_generations = set(list_vectors("evidence")) if list_vectors else set()
+        vector_generations = set(list_vectors("evidence", self.workspace_id)) if list_vectors else set()
         generations = sorted(set(published) | vector_generations)
         job_protected = self._protected_generations(workspace_root)
         active = self.store.active_generation()
@@ -124,7 +139,7 @@ class CorpusPipeline:
                 continue
             if purge_vector:
                 try:
-                    self.vector_store.delete_generation("evidence", generation)
+                    self.vector_store.delete_generation("evidence", generation, self.workspace_id)
                 except Exception:
                     failures.append({"generation": generation, "error": "vector cleanup failed"})
                     continue
@@ -154,6 +169,7 @@ class CorpusPipeline:
             return self._run(dry_run=dry_run, resume=resume)
 
     def run_as_job(self, **kwargs) -> PipelineResult:
+        self.workspace_id = kwargs["workspace_id"]
         with self.store.writer_lock():
             return self._run_as_job(**kwargs)
 
@@ -259,6 +275,7 @@ class CorpusPipeline:
                 vector_generation=plan["generation"],
                 documents=tuple(documents), chunks=tuple(chunks),
                 metadata={
+                    "workspace_id": self.workspace_id,
                     "compatibility_fingerprint": compatibility,
                     "fingerprints": plan["fingerprints"],
                     "removed": plan["removed"],
@@ -289,7 +306,7 @@ class CorpusPipeline:
             changed_docs = {doc.document_id for doc in manifest.documents if doc.source_id in plan["changed"]}
             parts = [part for part in manifest.chunks if part.document_id in changed_docs]
             embeddings = read(context, "embeddings.json")
-            return [self._vector_record(part, vector, plan["generation"])
+            return [self._vector_record(part, vector, plan["generation"], self.workspace_id)
                     for part, vector in zip(parts, embeddings, strict=True)]
 
         def compensate(context: JobContext) -> None:
@@ -297,7 +314,7 @@ class CorpusPipeline:
             if self.store.active_generation() != generation:
                 self.store.discard(generation)
             try:
-                self.vector_store.delete_generation("evidence", generation)
+                self.vector_store.delete_generation("evidence", generation, self.workspace_id)
             except Exception:
                 pass
             write(context, "compensated.json", {"generation": generation})
@@ -495,6 +512,7 @@ class CorpusPipeline:
                 vector_generation=generation,
                 documents=tuple(documents), chunks=tuple(chunks),
                 metadata={
+                    "workspace_id": self.workspace_id,
                     "compatibility_fingerprint": compatibility,
                     "fingerprints": fingerprints,
                     "removed": list(removed),
@@ -508,7 +526,7 @@ class CorpusPipeline:
                 raise PipelineError("embedding count mismatch")
             if any(len(vector) != self.embedding_dimensions for vector in embeddings):
                 raise PipelineError("embedding dimension mismatch")
-            records = [self._vector_record(part, vector, generation) for part, vector in zip(changed_chunks, embeddings, strict=True)]
+            records = [self._vector_record(part, vector, generation, self.workspace_id) for part, vector in zip(changed_chunks, embeddings, strict=True)]
             if records:
                 written = self.vector_store.upsert("evidence", records)
                 vector_written = True
@@ -547,17 +565,21 @@ class CorpusPipeline:
             pass
         if vector_written:
             try:
-                self.vector_store.delete_generation("evidence", generation)
+                self.vector_store.delete_generation("evidence", generation, self.workspace_id)
             except Exception:
                 pass
 
     @staticmethod
-    def _vector_record(chunk: CanonicalChunk, embedding: list[float], generation: str):
+    def _vector_record(
+        chunk: CanonicalChunk, embedding: list[float], generation: str, workspace_id: str,
+    ):
         record = VectorRecord(
-            id=f"{generation}:{chunk.chunk_id}", kind="evidence", ref=chunk.document_id,
+            id=f"{workspace_id}:{generation}:{chunk.chunk_id}",
+            kind="evidence", ref=chunk.document_id,
             title=str(chunk.metadata.get("title", "")), content=chunk.content,
             metadata={
                 **dict(chunk.metadata), "document_id": chunk.document_id,
+                "workspace_id": workspace_id,
                 "source_uri": chunk.source_uri, "ordinal": chunk.ordinal,
                 "vector_generation": generation,
             },
diff --git a/harness/tht/ports/vector.py b/harness/tht/ports/vector.py
index 57da32a8..9fd1cd8d 100644
--- a/harness/tht/ports/vector.py
+++ b/harness/tht/ports/vector.py
@@ -80,9 +80,9 @@ class VectorStore(Protocol):
 
     def upsert(self, collection: str, records: list[VectorWriteRecord]) -> int: ...
 
-    def delete_generation(self, collection: str, generation: str) -> int: ...
+    def delete_generation(self, collection: str, generation: str, workspace_id: str) -> int: ...
 
-    def list_evidence_generations(self, collection: str) -> list[str]: ...
+    def list_evidence_generations(self, collection: str, workspace_id: str) -> list[str]: ...
 
 
 __all__ = [
diff --git a/harness/tht/search/evidence.py b/harness/tht/search/evidence.py
index a2d24f93..47ff2718 100644
--- a/harness/tht/search/evidence.py
+++ b/harness/tht/search/evidence.py
@@ -30,7 +30,8 @@ class ActiveEvidenceSearcher:
                 hits.extend(self.delegate.search(embedding, **kwargs))
             if include_evidence:
                 manifest = self.corpus.active_manifest()
-                if manifest is not None:
+                workspace_id = manifest.metadata.get("workspace_id") if manifest else None
+                if manifest is not None and isinstance(workspace_id, str):
                     by_generation: dict[str, list[str]] = {}
                     mapping = dict(manifest.metadata.get("document_generations", {}))
                     for document in manifest.documents:
@@ -43,6 +44,7 @@ class ActiveEvidenceSearcher:
                             metadata_filter={
                                 "vector_generation": generation,
                                 "document_ids": sorted(document_ids),
+                                "workspace_id": workspace_id,
                             },
                         ))
         return sorted(hits, key=lambda hit: (-hit.similarity, hit.id))[:top_n]
diff --git a/harness/tht/vectorstore/rest_client.py b/harness/tht/vectorstore/rest_client.py
index 544e2e0d..dd7e1ac9 100644
--- a/harness/tht/vectorstore/rest_client.py
+++ b/harness/tht/vectorstore/rest_client.py
@@ -128,13 +128,16 @@ class VectorRestClient:
             return len(payload)
         return len(rows)
 
-    def delete_generation(self, table_name: str, generation: str) -> int:
+    def delete_generation(self, table_name: str, generation: str, workspace_id: str) -> int:
         if table_name != "evidence" or re.fullmatch(r"gen:[0-9a-f]{32}", generation) is None:
             raise ValueError("generation must be canonical")
+        if re.fullmatch(r"[a-z][a-z0-9_-]{0,63}", workspace_id) is None:
+            raise ValueError("workspace namespace must be canonical")
         try:
             payload = self._call(
                 "delete_vector_generation",
-                {"table_name": table_name, "kind": "evidence", "generation": generation},
+                {"table_name": table_name, "kind": "evidence", "generation": generation,
+                 "workspace_id": workspace_id},
             )
         except VectorRestError as error:
             if "HTTP 404" in str(error):
@@ -146,11 +149,13 @@ class VectorRestClient:
             return int(payload.get("deleted", 0))
         return 0
 
-    def list_evidence_generations(self, table_name: str) -> list[str]:
+    def list_evidence_generations(self, table_name: str, workspace_id: str) -> list[str]:
+        if re.fullmatch(r"[a-z][a-z0-9_-]{0,63}", workspace_id) is None:
+            raise ValueError("workspace namespace must be canonical")
         try:
             rows = self._call(
                 "list_evidence_generations",
-                {"table_name": table_name, "kind": "evidence"},
+                {"table_name": table_name, "kind": "evidence", "workspace_id": workspace_id},
             ) or []
         except VectorRestError as error:
             if "HTTP 404" in str(error):