fix: fix function call need send sig back to vertex

[fatelei]

fix issue langgenius/dify#30729

Related Issues or Context

This PR contains Changes to Non-Plugin

• Documentation
• Other

This PR contains Changes to Non-LLM Models Plugin

• I have Run Comprehensive Tests Relevant to My Changes

This PR contains Changes to LLM Models Plugin

• My Changes Affect Message Flow Handling (System Messages and User→Assistant Turn-Taking)

• My Changes Affect Tool Interaction Flow (Multi-Round Usage and Output Handling, for both Agent App and Agent Node)

• My Changes Affect Multimodal Input Handling (Images, PDFs, Audio, Video, etc.)

• My Changes Affect Multimodal Output Generation (Images, Audio, Video, etc.)

• My Changes Affect Structured Output Format (JSON, XML, etc.)

• My Changes Affect Token Consumption Metrics

• My Changes Affect Other LLM Functionalities (Reasoning Process, Grounding, Prompt Caching, etc.)

• Other Changes (Add New Models, Fix Model Parameters etc.)

Version Control (Any Changes to the Plugin Will Require Bumping the Version)

• I have Bumped Up the Version in Manifest.yaml (Top-Level Version Field, Not in Meta Section)

Dify Plugin SDK Version

• I have Ensured dify_plugin>=0.3.0,<0.6.0 is in requirements.txt (SDK docs)

Environment Verification (If Any Code Changes)

Local Deployment Environment

• Dify Version is: v1.11.2

SaaS Environment

• I have Tested My Changes on cloud.dify.ai with a Clean Environment That Matches the Production Configuration

[gemini-code-assist]

Summary of Changes

Hello @fatelei, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical issue in the Vertex AI integration where essential function call signatures were not being properly handled. By introducing mechanisms to capture these signatures from model outputs and re-attach them to subsequent function call prompts, the PR significantly enhances the reliability and contextual understanding of function calls within the Vertex AI plugin.

Highlights

• Bug Fix: Vertex AI Function Call Signatures: Implemented a fix to correctly capture and propagate thought_signature from Vertex AI model responses back into subsequent function call messages. This ensures that the Vertex AI model receives necessary context for its function calls.
• New Signature Extraction Logic: Added a new private method, _extract_thought_signature, to robustly parse thought_signature from various part formats (snake_case, camelCase, dict, extraContent) within Vertex AI responses.
• Version Bump: The models/vertex_ai/manifest.yaml file has been updated, incrementing the plugin version from 0.0.34 to 0.0.35.

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[gemini-code-assist]

Code Review

This pull request adds support for handling thought_signature from Vertex AI, which is captured from the model's response and sent back in subsequent tool call messages. The implementation correctly modifies the response handlers and message formatters. However, my main feedback concerns the repeated use of try...except Exception: pass. While this makes the implementation robust to some failures, it also silences all errors, which can hide bugs and make debugging extremely difficult. I've left specific comments on these blocks, recommending at least logging the exceptions. I also noted some code duplication that could be refactored into a helper method to improve maintainability.