diff --git a/api/tests/unit_tests/core/model_runtime/test_model_provider_factory.py b/api/tests/unit_tests/core/model_runtime/test_model_provider_factory.py
index 205a27ffdb..766280dbc7 100644
--- a/api/tests/unit_tests/core/model_runtime/test_model_provider_factory.py
+++ b/api/tests/unit_tests/core/model_runtime/test_model_provider_factory.py
@@ -111,6 +111,52 @@ def test_model_provider_factory_requires_runtime() -> None:
         ModelProviderFactory(model_runtime=None)  # type: ignore[arg-type]
 
 
+def test_model_provider_factory_get_providers_returns_runtime_providers() -> None:
+    providers = [
+        _build_provider(
+            provider="langgenius/openai/openai",
+            provider_name="openai",
+            supported_model_types=[ModelType.LLM],
+        )
+    ]
+    factory = ModelProviderFactory(model_runtime=_FakeModelRuntime(providers))
+
+    result = factory.get_providers()
+
+    assert list(result) == providers
+    assert result is not providers
+
+
+def test_model_provider_factory_get_provider_schema_delegates_to_provider_lookup() -> None:
+    provider = _build_provider(
+        provider="langgenius/openai/openai",
+        provider_name="openai",
+        supported_model_types=[ModelType.LLM],
+    )
+    factory = ModelProviderFactory(model_runtime=_FakeModelRuntime([provider]))
+
+    result = factory.get_provider_schema("openai")
+
+    assert result is provider
+
+
+def test_model_provider_factory_raises_for_unknown_provider() -> None:
+    factory = ModelProviderFactory(
+        model_runtime=_FakeModelRuntime(
+            [
+                _build_provider(
+                    provider="langgenius/openai/openai",
+                    provider_name="openai",
+                    supported_model_types=[ModelType.LLM],
+                )
+            ]
+        )
+    )
+
+    with pytest.raises(ValueError, match="Invalid provider: anthropic"):
+        factory.get_model_provider("anthropic")
+
+
 def test_model_provider_factory_get_models_filters_provider_and_model_type() -> None:
     providers = [
         _build_provider(
@@ -135,6 +181,47 @@ def test_model_provider_factory_get_models_filters_provider_and_model_type() ->
     assert [model.model for model in results[0].models] == ["gpt-4o-mini"]
 
 
+def test_model_provider_factory_get_models_skips_providers_without_requested_model_type() -> None:
+    providers = [
+        _build_provider(
+            provider="langgenius/openai/openai",
+            provider_name="openai",
+            supported_model_types=[ModelType.LLM],
+            models=[_build_model("gpt-4o-mini", ModelType.LLM)],
+        ),
+        _build_provider(
+            provider="langgenius/elevenlabs/elevenlabs",
+            provider_name="elevenlabs",
+            supported_model_types=[ModelType.TTS],
+            models=[_build_model("eleven_multilingual_v2", ModelType.TTS)],
+        ),
+    ]
+    factory = ModelProviderFactory(model_runtime=_FakeModelRuntime(providers))
+
+    results = factory.get_models(model_type=ModelType.TTS)
+
+    assert len(results) == 1
+    assert results[0].provider == "langgenius/elevenlabs/elevenlabs"
+    assert [model.model for model in results[0].models] == ["eleven_multilingual_v2"]
+
+
+def test_model_provider_factory_get_models_without_model_type_keeps_all_provider_models() -> None:
+    providers = [
+        _build_provider(
+            provider="langgenius/openai/openai",
+            provider_name="openai",
+            supported_model_types=[ModelType.LLM, ModelType.TTS],
+            models=[_build_model("gpt-4o-mini", ModelType.LLM), _build_model("tts-1", ModelType.TTS)],
+        )
+    ]
+    factory = ModelProviderFactory(model_runtime=_FakeModelRuntime(providers))
+
+    results = factory.get_models(provider="openai")
+
+    assert len(results) == 1
+    assert [model.model for model in results[0].models] == ["gpt-4o-mini", "tts-1"]
+
+
 def test_model_provider_factory_validates_provider_credentials() -> None:
     runtime = _FakeModelRuntime(
         [
@@ -169,6 +256,23 @@ def test_model_provider_factory_validates_provider_credentials() -> None:
     )
 
 
+def test_model_provider_factory_provider_credentials_validate_requires_schema() -> None:
+    factory = ModelProviderFactory(
+        model_runtime=_FakeModelRuntime(
+            [
+                _build_provider(
+                    provider="langgenius/openai/openai",
+                    provider_name="openai",
+                    supported_model_types=[ModelType.LLM],
+                )
+            ]
+        )
+    )
+
+    with pytest.raises(ValueError, match="Provider openai does not have provider_credential_schema"):
+        factory.provider_credentials_validate(provider="openai", credentials={"api_key": "secret"})
+
+
 def test_model_provider_factory_validates_model_credentials() -> None:
     runtime = _FakeModelRuntime(
         [
@@ -208,6 +312,28 @@ def test_model_provider_factory_validates_model_credentials() -> None:
     )
 
 
+def test_model_provider_factory_model_credentials_validate_requires_schema() -> None:
+    factory = ModelProviderFactory(
+        model_runtime=_FakeModelRuntime(
+            [
+                _build_provider(
+                    provider="langgenius/openai/openai",
+                    provider_name="openai",
+                    supported_model_types=[ModelType.LLM],
+                )
+            ]
+        )
+    )
+
+    with pytest.raises(ValueError, match="Provider openai does not have model_credential_schema"):
+        factory.model_credentials_validate(
+            provider="openai",
+            model_type=ModelType.LLM,
+            model="gpt-4o-mini",
+            credentials={"api_key": "secret"},
+        )
+
+
 def test_model_provider_factory_get_model_schema_and_icon_use_canonical_provider() -> None:
     runtime = _FakeModelRuntime(
         [
@@ -275,3 +401,20 @@ def test_model_provider_factory_builds_model_type_instances(
     instance = factory.get_model_type_instance("openai", model_type)
 
     assert isinstance(instance, expected_type)
+
+
+def test_model_provider_factory_rejects_unsupported_model_type() -> None:
+    factory = ModelProviderFactory(
+        model_runtime=_FakeModelRuntime(
+            [
+                _build_provider(
+                    provider="langgenius/openai/openai",
+                    provider_name="openai",
+                    supported_model_types=[ModelType.LLM],
+                )
+            ]
+        )
+    )
+
+    with pytest.raises(ValueError, match="Unsupported model type: unsupported"):
+        factory.get_model_type_instance("openai", "unsupported")  # type: ignore[arg-type]