.Net: Add ThoughtSignature support for Gemini function calling #13418
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
… calling
Implements support for Gemini's thoughtSignature token which is required
when using function calling with thinking mode enabled (Gemini 2.5 Pro).
Changes:
- Add ThoughtSignature property to GeminiPart for JSON serialization
- Add ThoughtSignature property to GeminiFunctionToolCall (follows OpenAI Id pattern)
- Add constructor overload to GeminiChatMessageContent accepting GeminiPart[]
- Update response processing to capture ThoughtSignature from function calls
- Add ThoughtSignature to GeminiMetadata for text responses
- Include ThoughtSignature when building request parts for function calls
- Restore ThoughtSignature from Metadata for text response history
- Fix empty ToolCalls check in streaming path (is not null -> is { Count: > 0 })
- Fix grammar: 'an Gemini' -> 'a Gemini' in XML doc
Fixes microsoft#13417
Add comprehensive unit tests for ThoughtSignature functionality: - GeminiPartTests: 8 tests for serialization/deserialization - GeminiFunctionToolCallTests: 5 tests for ThoughtSignature capture - GeminiRequestTests: 7 tests for request building with ThoughtSignature - GeminiMetadataTests: 4 tests for ThoughtSignature property (new file) - GeminiChatGenerationFunctionCallingTests: 3 tests for response processing - GeminiChatStreamingFunctionCallingTests: 2 tests for empty ToolCalls handling Add test data files: - chat_function_with_thought_signature_response.json - chat_text_with_thought_signature_response.json Fix streaming auto-invoke loop: - Reset LastMessage at start of each iteration to detect tool calls - Exit loop when no tool calls found (prevents infinite loop) All 376 tests pass.
moonbox3
added
.NET
github-actions
bot
changed the title
Contributor
Author
|
@microsoft-github-policy-service agree |
scutuatua-crypto
approved these changes
Dec 14, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Motivation and Context
Fixes #13417
Gemini 2.5/3 Pro with thinking enabled requires
thoughtSignaturetokens for function calling. Without this fix, function calling fails with HTTP 400:This PR implements full ThoughtSignature support as specified in Google's Thought Signatures documentation.
Full Specification used for this Fix is attached.
Description
This PR adds
thoughtSignaturesupport to the Gemini connector:Model Changes:
ThoughtSignatureproperty toGeminiPartfor JSON serializationThoughtSignatureproperty toGeminiFunctionToolCallto carry signature through SK abstractionsThoughtSignatureproperty toGeminiMetadatafor text response signaturesGeminiChatMessageContentacceptingGeminiPart[]for signature captureResponse Processing:
thoughtSignaturefrom function call responses intoGeminiFunctionToolCallthoughtSignaturefrom text responses intoGeminiMetadataRequest Building:
thoughtSignatureto function call parts when building requests from chat historythoughtSignatureto text parts for model messagesBug Fixes:
Test Coverage:
Contribution Checklist
semantic-kernel-gemini-connector-pr.md