fix(ui): restore Z.AI credential fields in provider catalog (#49325)

Carry the Z.AI catalog fix from #40088 and move its regression into the mapped unit test file.

Co-authored-by: Chaitanya Laxman <chaitanyalaxman118@gmail.com>
Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/public_endpoints/provider_create_fields.json

@@ -4285,6 +4285,34 @@
     ],
     "default_model_placeholder": "gpt-3.5-turbo"
   },
+  {
+    "provider": "ZAI",
+    "provider_display_name": "Z.AI (Zhipu AI)",
+    "litellm_provider": "zai",
+    "credential_fields": [
+      {
+        "key": "api_base",
+        "label": "API Base",
+        "placeholder": "https://api.z.ai/api/paas/v4",
+        "tooltip": null,
+        "required": false,
+        "field_type": "text",
+        "options": null,
+        "default_value": null
+      },
+      {
+        "key": "api_key",
+        "label": "API Key",
+        "placeholder": null,
+        "tooltip": null,
+        "required": true,
+        "field_type": "password",
+        "options": null,
+        "default_value": null
+      }
+    ],
+    "default_model_placeholder": "zai/glm-4.5"
+  },
   {
     "provider": "ZeroGPU",
     "provider_display_name": "ZeroGPU",

tests/unit/proxy/public_endpoints/test_public_endpoints.py

@@ -408,6 +408,34 @@ def test_cognition_provider_fields():
     assert fields_by_key["api_base"]["required"] is False
 
 
+def test_zai_provider_fields():
+    from litellm.llms.zai.chat.transformation import ZAI_API_BASE
+
+    app_instance: Final = FastAPI()
+    app_instance.include_router(router)
+    test_client: Final = TestClient(app_instance)
+
+    response: Final = test_client.get("/public/providers/fields")
+    assert response.status_code == 200
+    providers: Final = response.json()
+
+    zai: Final = next((p for p in providers if p["provider"] == "ZAI"), None)
+    assert zai is not None, "Z.AI provider entry not found"
+
+    assert zai["provider_display_name"] == "Z.AI (Zhipu AI)"
+    assert zai["litellm_provider"] == "zai"
+    assert zai["default_model_placeholder"].startswith("zai/")
+
+    fields_by_key: Final = {f["key"]: f for f in zai["credential_fields"]}
+
+    assert fields_by_key["api_key"]["required"] is True
+    assert fields_by_key["api_key"]["field_type"] == "password"
+
+    assert fields_by_key["api_base"]["required"] is False
+    assert fields_by_key["api_base"]["field_type"] == "text"
+    assert fields_by_key["api_base"]["placeholder"] == ZAI_API_BASE
+
+
 def test_zerogpu_add_model_form_defaults_resolve_to_a_priced_zerogpu_model():
     import litellm
     from litellm.litellm_core_utils.get_llm_provider_logic import get_llm_provider
@@ -611,7 +639,6 @@ ADD_MODEL_UNLISTED_PROVIDERS: Final = frozenset(
         "transcribe",
         "valkey",
         "xiaomi_mimo",
-        "zai",
     }
 )