feat: support image inputs in assistant tests

backend/tests/test_pipeline_knowledge.py

@@ -9,8 +9,8 @@ from services.pipecat.pipeline import (
     KnowledgeRetrievalProcessor,
     UserTurnRoutingProcessor,
     _knowledge_tool_description,
-    _workflow_vision_uses_main_llm,
 )
+from services.vision import resolve_vision_input
 
 
 class KnowledgeToolDescriptionTest(unittest.TestCase):
@@ -159,29 +159,36 @@ class WorkflowVisionModeTest(unittest.TestCase):
                     capability="LLM",
                     interface_type="openai-llm",
                     support_image_input=True,
-                )
+                ),
+                "auxiliary_vision": RuntimeModelResource(
+                    id="auxiliary_vision",
+                    name="独立视觉模型",
+                    capability="LLM",
+                    interface_type="openai-llm",
+                    support_image_input=True,
+                ),
             },
         )
 
         self.assertTrue(
-            _workflow_vision_uses_main_llm(
+            resolve_vision_input(
                 cfg,
                 {
                     "enabled": True,
                     "llm_resource_id": "agent_llm",
                     "vision_model_resource_id": None,
                 },
-            )
+            ).native
         )
         self.assertFalse(
-            _workflow_vision_uses_main_llm(
+            resolve_vision_input(
                 cfg,
                 {
                     "enabled": True,
                     "llm_resource_id": "agent_llm",
                     "vision_model_resource_id": "auxiliary_vision",
                 },
-            )
+            ).native
         )
 
     def test_rejects_a_non_visual_active_agent_llm(self):
@@ -199,7 +206,7 @@ class WorkflowVisionModeTest(unittest.TestCase):
         )
 
         with self.assertRaisesRegex(ValueError, "不支持图片输入"):
-            _workflow_vision_uses_main_llm(
+            resolve_vision_input(
                 cfg,
                 {
                     "enabled": True,