The Gemini REST API returns thoughtSignature as a sibling part field:
{ "functionCall": {...}, "thoughtSignature": "..." }
not inside functionCall. We were reading part.functionCall.thought_signature
(always undefined) and writing fc.thought_signature inside the functionCall
object (also wrong). Now correctly reads part.thoughtSignature and writes
part.thoughtSignature when building history.
Made-with: Cursor
Mark Henderson
e08405ffbf