diff --git a/open-sse/executors/antigravity.ts b/open-sse/executors/antigravity.ts
index a5ed157cf6..85656098d3 100644
--- a/open-sse/executors/antigravity.ts
+++ b/open-sse/executors/antigravity.ts
@@ -757,10 +757,19 @@ export class AntigravityExecutor extends BaseExecutor {
           );
         }
 
+        const getChunkedOrFixedBody = (bodyStr: string) => {
+          if (stream) {
+            return (async function* () {
+              yield new TextEncoder().encode(bodyStr);
+            })();
+          }
+          return bodyStr;
+        };
+
         let response = await fetch(url, {
           method: "POST",
           headers: finalHeaders,
-          body: serializedRequest.bodyString,
+          body: getChunkedOrFixedBody(serializedRequest.bodyString),
           signal,
         });
 
@@ -771,7 +780,7 @@ export class AntigravityExecutor extends BaseExecutor {
           response = await fetch(url, {
             method: "POST",
             headers: retryHeaders,
-            body: serializedRequest.bodyString,
+            body: getChunkedOrFixedBody(serializedRequest.bodyString),
             signal,
           });
           finalHeaders = retryHeaders;
@@ -840,7 +849,7 @@ export class AntigravityExecutor extends BaseExecutor {
                   const creditsResp = await fetch(url, {
                     method: "POST",
                     headers: finalCreditsHeaders,
-                    body: serializedCreditsRequest.bodyString,
+                    body: getChunkedOrFixedBody(serializedCreditsRequest.bodyString),
                     signal,
                   });
                   if (creditsResp.ok || creditsResp.status !== HTTP_STATUS.RATE_LIMITED) {
diff --git a/open-sse/services/antigravityIdentity.ts b/open-sse/services/antigravityIdentity.ts
index a0bb1d902a..e3992eb250 100644
--- a/open-sse/services/antigravityIdentity.ts
+++ b/open-sse/services/antigravityIdentity.ts
@@ -83,18 +83,25 @@ export function getAntigravitySessionId(
   );
 }
 
+import os from "node:os";
+
+const STABLE_MACHINE_ID = crypto
+  .createHash("sha256")
+  .update(`omniroute:machine_id:${os.hostname()}`)
+  .digest("hex");
+
+const FORMATTED_MACHINE_ID = [
+  STABLE_MACHINE_ID.slice(0, 8),
+  STABLE_MACHINE_ID.slice(8, 12),
+  STABLE_MACHINE_ID.slice(12, 16),
+  STABLE_MACHINE_ID.slice(16, 20),
+  STABLE_MACHINE_ID.slice(20, 32),
+].join("-");
+
 export function deriveAntigravityMachineId(
-  credentials?: AntigravityCredentialsLike | null
+  _credentials?: AntigravityCredentialsLike | null
 ): string {
-  const key = getAntigravityAccountKey(credentials) || PROCESS_SESSION_ID;
-  const hex = crypto.createHash("sha256").update(`antigravity:${key}`).digest("hex");
-  return [
-    hex.slice(0, 8),
-    hex.slice(8, 12),
-    hex.slice(12, 16),
-    hex.slice(16, 20),
-    hex.slice(20, 32),
-  ].join("-");
+  return FORMATTED_MACHINE_ID;
 }
 
 export function getAntigravityVscodeSessionId(): string {
diff --git a/open-sse/translator/request/openai-to-gemini.ts b/open-sse/translator/request/openai-to-gemini.ts
index 2f362ddb73..58d0cbdb51 100644
--- a/open-sse/translator/request/openai-to-gemini.ts
+++ b/open-sse/translator/request/openai-to-gemini.ts
@@ -136,6 +136,27 @@ function extractClientThoughtSignature(toolCall: unknown): string | null {
   return typeof signature === "string" && signature.length > 0 ? signature : null;
 }
 
+function deepCleanUndefined(value: unknown, depth = 0): void {
+  if (depth > 10 || !value || typeof value !== "object") {
+    return;
+  }
+  if (Array.isArray(value)) {
+    for (const item of value) {
+      deepCleanUndefined(item, depth + 1);
+    }
+  } else {
+    const obj = value as Record<string, unknown>;
+    for (const key of Object.keys(obj)) {
+      const val = obj[key];
+      if (typeof val === "string" && val === "[undefined]") {
+        delete obj[key];
+      } else {
+        deepCleanUndefined(val, depth + 1);
+      }
+    }
+  }
+}
+
 function applyAntigravityGenerationDefaults(generationConfig: GeminiGenerationConfig) {
   const config = { ...generationConfig };
   if (config.topK === undefined) {
@@ -359,8 +380,9 @@ function openaiToGeminiBase(model, body, stream, toolNameOptions: GeminiToolName
     ...toolNameOptions,
     toolNameMap,
   });
-  if (geminiTools) {
+  if (geminiTools && geminiTools.length > 0) {
     result.tools = geminiTools;
+    result.toolConfig = { functionCallingConfig: { mode: "VALIDATED" } };
   }
 
   // Convert response_format to Gemini's responseMimeType/responseSchema
@@ -384,6 +406,8 @@ function openaiToGeminiBase(model, body, stream, toolNameOptions: GeminiToolName
     result._toolNameMap = changedToolNameMap;
   }
 
+  deepCleanUndefined(result);
+
   return result;
 }