Gemini: Add config.yaml setting for thought signatures (#5025)

default/config.yaml

@@ -287,6 +287,8 @@ claude:
 gemini:
   # API endpoint version ("v1beta" or "v1alpha")
   apiVersion: 'v1beta'
+  # Adds thought signatures to requests (if available). Only for Gemini 3 and above.
+  thoughtSignatures: true
   # Enables caching of the system prompt (if supported). Only for OpenRouter.
   # -- IMPORTANT! --
   # Use only when the prompt before the chat history is static and doesn't change between requests

src/prompt-converters.js

@@ -31,6 +31,8 @@ const GEMINI_MEDIA_RESOLUTION = {
     high: 'media_resolution_high',
 };
 
+const enableThoughtSignatures = !!getConfigValue('gemini.thoughtSignatures', true, 'boolean');
+
 /**
  * @typedef {object} PromptNames
  * @property {string} charName Character name
@@ -574,7 +576,7 @@ export function convertGooglePrompt(messages, model, useSysPrompt, names) {
             const textSignature = message.signature;
 
             parts.forEach((part) => {
-                if (textSignature && typeof part.text === 'string') {
+                if (enableThoughtSignatures && textSignature && typeof part.text === 'string') {
                     part.thoughtSignature = textSignature;
                 } else if (/gemini-3/.test(model)) {
                     // Gemini 3: Fall back to bypass magic for function calls (mandatory) and images