diff --git a/package-lock.json b/package-lock.json
index 00e131b..7d050fb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
     "name": "opencode-antigravity-auth",
-    "version": "1.2.7-beta.1",
+    "version": "1.2.8-beta.0",
     "lockfileVersion": 3,
     "requires": true,
     "packages": {
         "": {
             "name": "opencode-antigravity-auth",
-            "version": "1.2.7-beta.1",
+            "version": "1.2.8-beta.0",
             "license": "MIT",
             "dependencies": {
                 "@openauthjs/openauth": "^0.4.3",
diff --git a/package.json b/package.json
index dcea1bf..3dc83fd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "opencode-antigravity-auth",
-    "version": "1.2.7-beta.7",
+    "version": "1.2.8-beta.0",
     "description": "Google Antigravity IDE OAuth auth plugin for Opencode - access Gemini 3 Pro and Claude 4.5 using Google credentials",
     "main": "./dist/index.js",
     "types": "./dist/index.d.ts",
diff --git a/src/plugin/request.ts b/src/plugin/request.ts
index 4500b73..003a743 100644
--- a/src/plugin/request.ts
+++ b/src/plugin/request.ts
@@ -1110,6 +1110,9 @@ export function prepareAntigravityRequest(
         // Attempts to restore signatures from cache for multi-turn conversations
         // Handle both Gemini-style contents[] and Anthropic-style messages[] payloads.
         if (isClaude) {
+          // Step 0: Sanitize cross-model metadata (strips Gemini signatures when sending to Claude)
+          sanitizeCrossModelPayloadInPlace(requestPayload, { targetModel: effectiveModel });
+
           // Step 1: Strip corrupted/unsigned thinking blocks FIRST
           deepFilterThinkingBlocks(requestPayload, signatureSessionKey, getCachedSignature, true);