[Bugfix] diffusion end points allow model mismatch (#2805)

Signed-off-by: xiaohajiayou <923390377@qq.com>
Signed-off-by: Samit <285365963@qq.com>
Co-authored-by: Samit <285365963@qq.com>
Co-authored-by: SYLAR <125541396+lishunyang12@users.noreply.github.com>

tests/entrypoints/openai_api/test_image_server.py

@@ -851,6 +851,19 @@ def test_model_field_omitted_works(test_client):
     assert response.status_code == 200
 
 
+def test_generate_images_rejects_model_mismatch(test_client):
+    response = test_client.post(
+        "/v1/images/generations",
+        json={
+            "prompt": "test",
+            "model": "Qwen/Qwen-Image-2512",
+            "size": "1024x1024",
+        },
+    )
+    assert response.status_code == 400
+    assert "model mismatch" in response.json()["detail"].lower()
+
+
 def make_test_image_bytes(size=(64, 64)) -> bytes:
     img = Image.new(
         "RGB",
@@ -954,6 +967,20 @@ def test_image_edit_rejects_multiple_images_when_model_does_not_support_them(asy
     assert engine.captured_prompt is None
 
 
+def test_image_edit_rejects_model_mismatch(test_client):
+    img_bytes = make_test_image_bytes((16, 16))
+    response = test_client.post(
+        "/v1/images/edits",
+        files=[("image", img_bytes)],
+        data={
+            "prompt": "edit me",
+            "model": "Qwen/Qwen-Image-Edit",
+        },
+    )
+    assert response.status_code == 400
+    assert "model mismatch" in response.json()["detail"].lower()
+
+
 def test_image_edit_rejects_too_many_images_for_qwen_image_edit_2511(async_omni_test_client):
     engine = async_omni_test_client.app.state.engine_client
     engine.get_diffusion_od_config = lambda: SimpleNamespace(