fix: fix empty part to call gemini (#2367)

Author: fatelei

models/gemini/manifest.yaml

@@ -34,4 +34,4 @@ resource:
     tool:
       enabled: true
 type: plugin
-version: 0.7.2
+version: 0.7.3

models/gemini/models/llm/llm.py

@@ -578,7 +578,9 @@ def build_parts(
 
             # Handle text content (remove thinking tags)
             if message.content:
-                parts.extend(build_parts(message.content, is_assistant_tree=True))
+                part = build_parts(message.content, is_assistant_tree=True)
+                if part:
+                    parts.extend(part)
 
             # Handle tool calls
             # https://ai.google.dev/gemini-api/docs/function-calling?hl=zh-cn&example=chart#how-it-works
@@ -590,6 +592,10 @@ def build_parts(
                 _unsafe_part.thought_signature = DEFAULT_THOUGHT_SIGNATURE
                 parts.append(_unsafe_part)
 
+            # Filter out assistant messages with empty parts to avoid invalid requests
+            if not parts:
+                return None
+
             return types.Content(role="model", parts=parts)
 
         elif isinstance(message, SystemPromptMessage):
@@ -709,7 +715,7 @@ def _handle_generate_stream_response(
             if (
                 not chunk.candidates
                 or not chunk.candidates[0].content
-                or not chunk.candidates[0].content.parts
+                or (not chunk.candidates[0].content.parts and not chunk.candidates[0].finish_reason)
             ):
                 continue
             candidate = chunk.candidates[0]

models/gemini/requirements.txt

@@ -184,7 +184,7 @@ urllib3==2.6.0
     # via requests
 websockets==15.0.1
     # via google-genai
-werkzeug==3.1.4
+werkzeug>=3.0.3,<3.1.dev0
     # via
     #   dify-plugin
     #   flask