diff --git a/EvoScientist/model_registry/store.py b/EvoScientist/model_registry/store.py
index 2e2c0dd..43c52e1 100644
--- a/EvoScientist/model_registry/store.py
+++ b/EvoScientist/model_registry/store.py
@@ -25,7 +25,6 @@ from .errors import (
     CREDENTIAL_NOT_CONFIGURED,
     MODEL_CONFIGURATION_CHANGED,
     MODEL_DISABLED,
-    REGISTRY_REVISION_CONFLICT,
     RUN_CREDENTIAL_REVISION_UNAVAILABLE,
     ModelRegistryError,
 )
@@ -250,16 +249,17 @@ class ModelRuntimeStore:
         credential_writes: list[CredentialWrite] | None = None,
         validate: SaveValidator | None = None,
     ) -> RegistryV4:
-        """Compare-and-swap the registry inside one ``BEGIN IMMEDIATE`` transaction.
+        """Save the registry inside one ``BEGIN IMMEDIATE`` transaction.
 
-        Credential versions are written first (immutable, with incrementing
-        revisions), then the optional ``validate`` hook runs the section 9.2
-        save-time checks against the post-write state (so the verification
-        five-tuple sees the new credential revisions), then
-        the registry row is replaced with ``revision + 1``. A bootstrap
-        document atomically turns ``active`` the first time it carries an
-        enabled model, a valid primary, and a satisfied auth reference (4.3).
-        Any failure rolls the whole transaction back.
+        ``expected_revision`` is accepted for API compatibility but ignored:
+        saves are last-write-wins and the stored revision is always
+        ``current + 1``. Credential versions are written first (immutable,
+        with incrementing revisions), then the optional ``validate`` hook
+        runs the section 9.2 save-time checks against the post-write state,
+        then the registry row is replaced. A bootstrap document atomically
+        turns ``active`` the first time it carries an enabled model, a valid
+        primary, and a satisfied auth reference (4.3). Any failure rolls the
+        whole transaction back.
         """
         now = int(time.time())
         with self._lock:
@@ -271,17 +271,6 @@ class ModelRuntimeStore:
                 ).fetchone()
                 current_revision = int(row[0]) if row is not None else 1
                 current_state = str(row[1]) if row is not None else "bootstrap"
-                if current_revision != expected_revision:
-                    raise ModelRegistryError(
-                        REGISTRY_REVISION_CONFLICT,
-                        "registry revision conflict; reload and retry.",
-                        details=[
-                            {
-                                "path": "expected_revision",
-                                "code": REGISTRY_REVISION_CONFLICT,
-                            }
-                        ],
-                    )
                 for write in credential_writes or []:
                     self._write_credential_version(
                         connection, write.credential_id, write.secret_value, now=now
diff --git a/tests/test_model_registry_store.py b/tests/test_model_registry_store.py
index 33c31bd..fc5f271 100644
--- a/tests/test_model_registry_store.py
+++ b/tests/test_model_registry_store.py
@@ -11,7 +11,6 @@ import pytest
 from EvoScientist.model_registry.errors import (
     CREDENTIAL_NOT_CONFIGURED,
     MODEL_DISABLED,
-    REGISTRY_REVISION_CONFLICT,
     RUN_CREDENTIAL_REVISION_UNAVAILABLE,
     ModelRegistryError,
 )
@@ -184,15 +183,15 @@ class TestRegistrySave:
         # The failed save must not leave partial state behind.
         assert store.load_registry().revision == 1
 
-    def test_stale_expected_revision_conflicts(self, tmp_path):
+    def test_stale_expected_revision_is_ignored(self, tmp_path):
         store = ModelRuntimeStore(config_dir=tmp_path)
         store.save_registry(expected_revision=1, registry=_local_registry())
-        with pytest.raises(ModelRegistryError) as excinfo:
-            store.save_registry(expected_revision=1, registry=_local_registry())
-        assert excinfo.value.code == REGISTRY_REVISION_CONFLICT
-        assert store.load_registry().revision == 2
+        # expected_revision is accepted but ignored: last write wins.
+        saved = store.save_registry(expected_revision=1, registry=_local_registry())
+        assert saved.revision == 3
+        assert store.load_registry().revision == 3
 
-    def test_concurrent_saves_single_winner(self, tmp_path):
+    def test_concurrent_saves_last_write_wins(self, tmp_path):
         first = ModelRuntimeStore(config_dir=tmp_path)
         first.save_registry(expected_revision=1, registry=_local_registry())
 
@@ -214,8 +213,9 @@ class TestRegistrySave:
         for thread in threads:
             thread.join(timeout=30)
 
-        assert sorted(outcomes, key=str.lower) == ["ok", REGISTRY_REVISION_CONFLICT]
-        assert first.load_registry().revision == 3
+        assert outcomes == ["ok", "ok"]
+        # Both saves win: 1 (bootstrap) + initial save + two racing saves.
+        assert first.load_registry().revision == 4
 
     def test_defaults_must_reference_enabled_models(self, tmp_path):
         store = ModelRuntimeStore(config_dir=tmp_path)