fix: fix zai and others byok (#8991)

* fix: fix zai and other byok providers

* fix test

* get endpoint from typed provider and add test

* also add base_url on provider create

tests/test_server_providers.py

@@ -3143,3 +3143,100 @@ async def test_get_model_by_handle_prioritizes_byok_over_base(default_user, prov
     # The key assertion: org-specific (BYOK) model should be returned, not the global (base) model
     assert retrieved_model.organization_id == default_user.organization_id
     assert retrieved_model.provider_id == byok_provider.id
+
+
+@pytest.mark.asyncio
+async def test_byok_provider_uses_schema_default_base_url(default_user, provider_manager):
+    """Test that BYOK providers with schema-default base_url get correct model_endpoint.
+
+    This tests a bug where providers like ZAI have a schema-default base_url
+    (e.g., "https://api.z.ai/api/paas/v4/") that isn't stored in the database.
+    When list_llm_models_async reads from DB, the base_url is NULL, and if the code
+    uses provider.base_url directly instead of typed_provider.base_url, the
+    model_endpoint would be None/wrong, causing requests to go to the wrong endpoint.
+
+    The fix uses cast_to_subtype() to get the typed provider with schema defaults.
+    """
+    from letta.orm.provider import Provider as ProviderORM
+    from letta.schemas.providers import Provider as PydanticProvider
+    from letta.schemas.providers.zai import ZAIProvider
+    from letta.server.db import db_registry
+
+    test_id = generate_test_id()
+    provider_name = f"test-zai-{test_id}"
+
+    # Create a ZAI BYOK provider WITHOUT explicitly setting base_url
+    # This simulates what happens when a user creates a ZAI provider via the API
+    # The schema default "https://api.z.ai/api/paas/v4/" applies in memory but
+    # may not be stored in the database (base_url column is NULL)
+    byok_pydantic_provider = PydanticProvider(
+        name=provider_name,
+        provider_type=ProviderType.zai,
+        provider_category=ProviderCategory.byok,
+        organization_id=default_user.organization_id,
+        # NOTE: base_url is intentionally NOT set - this is the bug scenario
+        # The DB will have base_url=NULL
+    )
+    byok_pydantic_provider.resolve_identifier()
+
+    async with db_registry.async_session() as session:
+        byok_provider_orm = ProviderORM(**byok_pydantic_provider.model_dump(to_orm=True))
+        await byok_provider_orm.create_async(session, actor=default_user)
+        byok_provider = byok_provider_orm.to_pydantic()
+
+    # Verify base_url is None in the provider loaded from DB
+    assert byok_provider.base_url is None, "base_url should be NULL in DB for this test"
+    assert byok_provider.provider_type == ProviderType.zai
+
+    # Sync a model for the provider (simulating what happens after provider creation)
+    # Set last_synced so the server reads from DB instead of calling provider API
+    from datetime import datetime, timezone
+
+    async with db_registry.async_session() as session:
+        provider_orm = await ProviderORM.read_async(session, identifier=byok_provider.id, actor=None)
+        provider_orm.last_synced = datetime.now(timezone.utc)
+        await session.commit()
+
+    model_handle = f"{provider_name}/glm-4-flash"
+    byok_llm_model = LLMConfig(
+        model="glm-4-flash",
+        model_endpoint_type="zai",
+        model_endpoint="https://api.z.ai/api/paas/v4/",  # The correct endpoint
+        context_window=128000,
+        handle=model_handle,
+        provider_name=provider_name,
+        provider_category=ProviderCategory.byok,
+    )
+    await provider_manager.sync_provider_models_async(
+        provider=byok_provider,
+        llm_models=[byok_llm_model],
+        embedding_models=[],
+        organization_id=default_user.organization_id,
+    )
+
+    # Create server and list LLM models
+    server = SyncServer(init_with_default_org_and_user=False)
+    server.default_user = default_user
+    server.provider_manager = provider_manager
+
+    # List LLM models - this should use typed_provider.base_url (schema default)
+    # NOT provider.base_url (which is NULL in DB)
+    models = await server.list_llm_models_async(
+        actor=default_user,
+        provider_category=[ProviderCategory.byok],  # Only BYOK providers
+    )
+
+    # Find our ZAI model
+    zai_models = [m for m in models if m.handle == model_handle]
+    assert len(zai_models) == 1, f"Expected 1 ZAI model, got {len(zai_models)}"
+
+    zai_model = zai_models[0]
+
+    # THE KEY ASSERTION: model_endpoint should be the ZAI schema default,
+    # NOT None (which would cause requests to go to OpenAI's endpoint)
+    expected_endpoint = "https://api.z.ai/api/paas/v4/"
+    assert zai_model.model_endpoint == expected_endpoint, (
+        f"model_endpoint should be '{expected_endpoint}' from ZAI schema default, "
+        f"but got '{zai_model.model_endpoint}'. This indicates the bug where "
+        f"provider.base_url (NULL from DB) was used instead of typed_provider.base_url."
+    )