fix(i-c): BUG-036 behoben — Workflow-Instances GET lieferte 500 auf jeden Aufruf (Route übergab user_id/is_system_admin die die Service-Signatur nicht akzeptierte → TypeError); Service um optionale User-Filterung erweitert (Nicht-Admins sehen nur eigene Instanzen via initiated_by, Admins alle); Beweistest test_bug036_instances.py 2/2 grün

tests/test_bug036_instances.py

@@ -0,0 +1,35 @@
+"""Tests for BUG-036 fix — GET /api/v1/workflows/instances returned 500.
+
+Root cause: the route passed ``user_id``/``is_system_admin`` which the service
+signature did not accept -> TypeError -> 500 on every call.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from tests.conftest import ORIGIN_HEADER, login_client, seed_tenant_and_users
+
+
+@pytest.mark.asyncio
+async def test_list_instances_returns_200(client, db_session):
+    """GET /api/v1/workflows/instances must return 200 (was 500 before fix)."""
+    await seed_tenant_and_users(db_session)
+    await login_client(client, "admin@tenanta.com")
+
+    resp = await client.get("/api/v1/workflows/instances", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200, resp.text
+    data = resp.json()
+    assert "items" in data and "total" in data
+
+
+@pytest.mark.asyncio
+async def test_list_instances_status_filter_returns_200(client, db_session):
+    """Status filter variant also works after the signature fix."""
+    await seed_tenant_and_users(db_session)
+    await login_client(client, "admin@tenanta.com")
+
+    resp = await client.get(
+        "/api/v1/workflows/instances?status=running", headers=ORIGIN_HEADER
+    )
+    assert resp.status_code == 200, resp.text