fix(antigravity): scope cached thought signatures to the model family

open-sse/executors/antigravity.js

@@ -212,7 +212,7 @@ export class AntigravityExecutor extends BaseExecutor {
       const modifiedParts = parts?.map(p => {
         if (!p.functionCall) return p;
         const callId = p.functionCall.id;
-        const cachedSig = callId ? getGeminiThoughtSignatureSync(callId, sessionId) : null;
+        const cachedSig = callId ? getGeminiThoughtSignatureSync(callId, sessionId, body.model || model) : null;
         const callSig = p.thoughtSignature || cachedSig || (!firstFunctionCallSeen ? DEFAULT_THINKING_AG_SIGNATURE : undefined);
         firstFunctionCallSeen = true;
         if (callSig) {