fix: harden model catalog projections

harness/tests/test_corpus_pipeline.py

@@ -105,11 +105,13 @@ def item(name, fingerprint):
     )
 
 
-def pipeline(tmp_path, source, *, embedder=None, vectors=None, model="model-a", policy=None,
+def pipeline(tmp_path, source, *, embedder=None, vectors=None, model="model-a",
+             embedding_id=None, policy=None,
              retain=3, candidate_evaluator=None):
     return CorpusPipeline(
         store=CorpusStore(tmp_path / "corpus"), sources=[source],
         embedder=embedder or Embedder(), vector_store=vectors or Vectors(),
+        embedding_id=embedding_id,
         embedding_model=model, embedding_dimensions=3,
         chunk_policy=policy or ChunkPolicy(version="chunk-v1", max_chars=100),
         pipeline_version="evidence-v1",
@@ -875,6 +877,24 @@ def test_model_or_chunk_policy_change_forces_full_rebuild(tmp_path):
     assert source.acquire_calls == ["fs:one"]
 
 
+def test_canonical_embedding_id_change_forces_full_rebuild_and_is_persisted(tmp_path):
+    one = item("one", "a")
+    first = pipeline(
+        tmp_path, Source([(one, "hello")]), model="same-upstream",
+        embedding_id="ollama/catalog-a",
+    ).run()
+    assert first.manifest.embedding_id == "ollama/catalog-a"
+
+    source = Source([(one, "hello")])
+    changed = pipeline(
+        tmp_path, source, model="same-upstream", embedding_id="ollama/catalog-b",
+    ).run()
+
+    assert changed.changed == ("fs:one",)
+    assert changed.manifest.embedding_id == "ollama/catalog-b"
+    assert source.acquire_calls == ["fs:one"]
+
+
 def test_partial_vector_failure_never_changes_active_or_exposes_generation(tmp_path):
     one = item("one", "a")
     good = pipeline(tmp_path, Source([(one, "old")]))