diff --git a/.github/workflows/unit_tests.yml b/.github/workflows/unit_tests.yml
index fa4fdf2a..15d4cfe9 100644
--- a/.github/workflows/unit_tests.yml
+++ b/.github/workflows/unit_tests.yml
@@ -60,3 +60,15 @@ jobs:
             -e DB_PASSWORD=test \
             -e DB_PORT=5432 \
             model-test pytest -vv -m 'not integration'
+
+      # The DDD rewrite (tests/) defines SQLModel table classes that map to the
+      # same physical tables as the legacy backend models. Both sets share the
+      # one global SQLModel.metadata, so they cannot be imported into the same
+      # pytest process. It runs as a separate invocation until the legacy
+      # models are retired. Its DB is spawned in-process by pytest-postgresql,
+      # so no DB service or env is required.
+      - name: Run DDD tests
+        run: |
+          docker run --rm \
+            --network host \
+            model-test pytest -vv tests/
diff --git a/pytest.ini b/pytest.ini
index 5044465b..99cc8e1b 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -4,7 +4,6 @@ log_cli = true
 log_cli_level = INFO
 addopts = --cov-report term-missing --cov=etl/epc --cov=recommendations --cov=backend --cov=etl/epc_clean --cov=etl/spatial
 testpaths =
-    tests
     recommendations/tests
     backend/tests
     backend/address2UPRN/tests