fix: improve MiniMax code plan integration (#1169)

This PR improves MiniMax Code Plan integration in DeerFlow by fixing three issues in the current flow: stream errors were not clearly surfaced in the UI, the frontend could not display the actual provider model ID, and MiniMax reasoning output could leak into final assistant content as inline <think>...</think>. The change adds a MiniMax-specific adapter, exposes real model IDs end-to-end, and adds a frontend fallback for historical messages.
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/tests/test_client.py

@@ -28,6 +28,7 @@ def mock_app_config():
     """Provide a minimal AppConfig mock."""
     model = MagicMock()
     model.name = "test-model"
+    model.model = "test-model"
     model.supports_thinking = False
     model.supports_reasoning_effort = False
     model.model_dump.return_value = {"name": "test-model", "use": "langchain_openai:ChatOpenAI"}
@@ -98,6 +99,7 @@ class TestConfigQueries:
         assert len(result["models"]) == 1
         assert result["models"][0]["name"] == "test-model"
         # Verify Gateway-aligned fields are present
+        assert "model" in result["models"][0]
         assert "display_name" in result["models"][0]
         assert "supports_thinking" in result["models"][0]
 
@@ -420,6 +422,7 @@ class TestGetModel:
     def test_found(self, client):
         model_cfg = MagicMock()
         model_cfg.name = "test-model"
+        model_cfg.model = "test-model"
         model_cfg.display_name = "Test Model"
         model_cfg.description = "A test model"
         model_cfg.supports_thinking = True
@@ -429,6 +432,7 @@ class TestGetModel:
         result = client.get_model("test-model")
         assert result == {
             "name": "test-model",
+            "model": "test-model",
             "display_name": "Test Model",
             "description": "A test model",
             "supports_thinking": True,
@@ -1048,6 +1052,7 @@ class TestScenarioConfigManagement:
         # Get specific model
         model_cfg = MagicMock()
         model_cfg.name = model_name
+        model_cfg.model = model_name
         model_cfg.display_name = None
         model_cfg.description = None
         model_cfg.supports_thinking = False
@@ -1503,6 +1508,7 @@ class TestGatewayConformance:
     def test_list_models(self, mock_app_config):
         model = MagicMock()
         model.name = "test-model"
+        model.model = "gpt-test"
         model.display_name = "Test Model"
         model.description = "A test model"
         model.supports_thinking = False
@@ -1515,10 +1521,12 @@ class TestGatewayConformance:
         parsed = ModelsListResponse(**result)
         assert len(parsed.models) == 1
         assert parsed.models[0].name == "test-model"
+        assert parsed.models[0].model == "gpt-test"
 
     def test_get_model(self, mock_app_config):
         model = MagicMock()
         model.name = "test-model"
+        model.model = "gpt-test"
         model.display_name = "Test Model"
         model.description = "A test model"
         model.supports_thinking = True
@@ -1532,6 +1540,7 @@ class TestGatewayConformance:
         assert result is not None
         parsed = ModelResponse(**result)
         assert parsed.name == "test-model"
+        assert parsed.model == "gpt-test"
 
     def test_list_skills(self, client):
         skill = MagicMock()