feat(antigravity): initial steps for Antigravity anti-ban alignment

open-sse/config/constants.js

@@ -1,3 +1,76 @@
+import { platform, arch } from "os";
+
+// === Antigravity Binary Alignment: Numeric Enums ===
+// Reference: Antigravity binary analysis - google.internal.cloud.code.v1internal.ClientMetadata
+
+// IDE Type enum (numeric values as expected by Cloud Code API)
+export const IDE_TYPE = {
+  UNSPECIFIED: 0,
+  JETSKI: 10,        // Internal codename for Gemini CLI
+  ANTIGRAVITY: 9,
+  PLUGINS: 7
+};
+
+// Platform enum (as specified in Antigravity binary)
+export const PLATFORM = {
+  UNSPECIFIED: 0,
+  DARWIN_AMD64: 1,
+  DARWIN_ARM64: 2,
+  LINUX_AMD64: 3,
+  LINUX_ARM64: 4,
+  WINDOWS_AMD64: 5
+};
+
+// Plugin type enum (as specified in Antigravity binary)
+export const PLUGIN_TYPE = {
+  UNSPECIFIED: 0,
+  CLOUD_CODE: 1,
+  GEMINI: 2
+};
+
+/**
+ * Get the platform enum value based on the current OS.
+ * @returns {number} Platform enum value
+ */
+export function getPlatformEnum() {
+  const os = platform();
+  const architecture = arch();
+
+  if (os === "darwin") {
+    return architecture === "arm64" ? PLATFORM.DARWIN_ARM64 : PLATFORM.DARWIN_AMD64;
+  } else if (os === "linux") {
+    return architecture === "arm64" ? PLATFORM.LINUX_ARM64 : PLATFORM.LINUX_AMD64;
+  } else if (os === "win32") {
+    return PLATFORM.WINDOWS_AMD64;
+  }
+  return PLATFORM.UNSPECIFIED;
+}
+
+/**
+ * Generate platform-specific User-Agent string.
+ * @returns {string} User-Agent in format "antigravity/version os/arch"
+ */
+export function getPlatformUserAgent() {
+  const os = platform();
+  const architecture = arch();
+  return `antigravity/1.16.5 ${os}/${architecture}`;
+}
+
+// Centralized client metadata (used in request bodies for loadCodeAssist, onboardUser, etc.)
+// Using numeric enum values as expected by the Cloud Code API
+export const CLIENT_METADATA = {
+  ideType: IDE_TYPE.ANTIGRAVITY,   // 9 - identifies as Antigravity client
+  platform: getPlatformEnum(),      // Runtime platform detection
+  pluginType: PLUGIN_TYPE.GEMINI    // 2
+};
+
+// Antigravity headers
+export const ANTIGRAVITY_HEADERS = {
+  "X-Client-Name": "antigravity",
+  "X-Client-Version": "1.107.0",
+  "x-goog-api-client": "gl-node/18.18.2 fire/0.8.6 grpc/1.10.x"
+};
+
 // Provider configurations
 export const PROVIDERS = {
   claude: {
@@ -78,7 +151,7 @@ export const PROVIDERS = {
     ],
     format: "antigravity",
     headers: {
-      "User-Agent": "antigravity/1.104.0 darwin/arm64"
+      "User-Agent": getPlatformUserAgent()
     },
     clientId: "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com",
     clientSecret: "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"
@@ -181,7 +254,7 @@ export const PROVIDERS = {
 export const CLAUDE_SYSTEM_PROMPT = "You are Claude Code, Anthropic's official CLI for Claude.";
 
 // Antigravity default system prompt (required for API to work)
-export const ANTIGRAVITY_DEFAULT_SYSTEM = "Please ignore the following [ignore]You are Antigravity, a powerful agentic AI coding assistant designed by the Google Deepmind team working on Advanced Agentic Coding.You are pair programming with a USER to solve their coding task. The task may require creating a new codebase, modifying or debugging an existing codebase, or simply answering a question.**Absolute paths only****Proactiveness**[/ignore]";
+export const ANTIGRAVITY_DEFAULT_SYSTEM = "You are Antigravity, a powerful agentic AI coding assistant designed by the Google Deepmind team working on Advanced Agentic Coding.You are pair programming with a USER to solve their coding task. The task may require creating a new codebase, modifying or debugging an existing codebase, or simply answering a question.**Absolute paths only****Proactiveness**";
 
 // OAuth endpoints
 export const OAUTH_ENDPOINTS = {

open-sse/executors/antigravity.js

@@ -1,6 +1,7 @@
 import crypto from "crypto";
 import { BaseExecutor } from "./base.js";
-import { PROVIDERS, OAUTH_ENDPOINTS, HTTP_STATUS } from "../config/constants.js";
+import { PROVIDERS, OAUTH_ENDPOINTS, HTTP_STATUS, ANTIGRAVITY_HEADERS } from "../config/constants.js";
+import { deriveSessionId, getCachedSignature } from "../utils/sessionManager.js";
 
 const MAX_RETRY_AFTER_MS = 10000;
 
@@ -16,28 +17,51 @@ export class AntigravityExecutor extends BaseExecutor {
     return `${baseUrl}/v1internal:${action}`;
   }
 
-  buildHeaders(credentials, stream = true) {
+  buildHeaders(credentials, stream = true, sessionId = null) {
     return {
       "Content-Type": "application/json",
       "Authorization": `Bearer ${credentials.accessToken}`,
       "User-Agent": this.config.headers?.["User-Agent"] || "antigravity/1.104.0 darwin/arm64",
-      "X-9Router-Source": "9router",
+      ...ANTIGRAVITY_HEADERS,
+      ...(sessionId && { "X-Machine-Session-Id": sessionId }),
       ...(stream && { "Accept": "text/event-stream" })
     };
   }
 
   transformRequest(model, body, stream, credentials) {
     const projectId = credentials?.projectId || this.generateProjectId();
-
+
+    const sessionId = body.request?.sessionId || deriveSessionId(credentials?.email || credentials?.connectionId);
+
+    // Get signature for this session (side-channel cache)
+    const cachedSignature = getCachedSignature(sessionId);
+    // DEBUG LOG
+    if (cachedSignature) {
+      console.log(`[AntigravityExecutor] Injecting cached signature for session ${sessionId.substring(0, 8)}...`);
+    } else {
+      // console.log(`[AntigravityExecutor] No cached signature for session ${sessionId.substring(0, 8)}...`);
+    }
+
     // Fix contents for Claude models via Antigravity
     const contents = body.request?.contents?.map(c => {
       let role = c.role;
       // functionResponse must be role "user" for Claude models
       if (c.parts?.some(p => p.functionResponse)) {
         role = "user";
       }
-      // Strip thought-only parts, keep thoughtSignature on functionCall parts (Gemini 3+ requires it)
-      const parts = c.parts?.filter(p => {
+
+      // Inject signature into functionCall parts
+      let parts = c.parts?.map(p => {
+        if (p.functionCall) {
+          // Use cached signature or random fallback to avoid static fingerprint
+          const signature = cachedSignature || crypto.randomUUID();
+          return { ...p, thoughtSignature: signature };
+        }
+        return p;
+      });
+
+      // Strip thought-only parts
+      parts = parts?.filter(p => {
         if (p.thought && !p.functionCall) return false;
         if (p.thoughtSignature && !p.functionCall && !p.text) return false;
         return true;
@@ -51,13 +75,13 @@ export class AntigravityExecutor extends BaseExecutor {
     const transformedRequest = {
       ...body.request,
       ...(contents && { contents }),
-      sessionId: body.request?.sessionId || this.generateSessionId(),
+      sessionId: sessionId,
       safetySettings: undefined,
-      toolConfig: body.request?.tools?.length > 0 
+      toolConfig: body.request?.tools?.length > 0
         ? { functionCallingConfig: { mode: "VALIDATED" } }
         : body.request?.toolConfig
     };
-    
+
     return {
       ...body,
       project: projectId,
@@ -108,7 +132,7 @@ export class AntigravityExecutor extends BaseExecutor {
   }
 
   generateSessionId() {
-    return `-${Math.floor(Math.random() * 9_000_000_000_000_000_000)}`;
+    return crypto.randomUUID() + Date.now().toString();
   }
 
   parseRetryHeaders(headers) {
@@ -118,7 +142,7 @@ export class AntigravityExecutor extends BaseExecutor {
     if (retryAfter) {
       const seconds = parseInt(retryAfter, 10);
       if (!isNaN(seconds) && seconds > 0) return seconds * 1000;
-      
+
       const date = new Date(retryAfter);
       if (!isNaN(date.getTime())) {
         const diff = date.getTime() - Date.now();
@@ -167,9 +191,10 @@ export class AntigravityExecutor extends BaseExecutor {
 
     for (let urlIndex = 0; urlIndex < fallbackCount; urlIndex++) {
       const url = this.buildUrl(model, stream, urlIndex);
-      const headers = this.buildHeaders(credentials, stream);
       const transformedBody = this.transformRequest(model, body, stream, credentials);
-
+      const sessionId = transformedBody.request?.sessionId;
+      const headers = this.buildHeaders(credentials, stream, sessionId);
+
       // Initialize retry counter for this URL
       if (!retryAttemptsByUrl[urlIndex]) {
         retryAttemptsByUrl[urlIndex] = 0;
@@ -200,7 +225,7 @@ export class AntigravityExecutor extends BaseExecutor {
           }
 
           if (retryMs && retryMs <= MAX_RETRY_AFTER_MS) {
-            log?.debug?.("RETRY", `${response.status} with Retry-After: ${Math.ceil(retryMs/1000)}s, waiting...`);
+            log?.debug?.("RETRY", `${response.status} with Retry-After: ${Math.ceil(retryMs / 1000)}s, waiting...`);
             await new Promise(resolve => setTimeout(resolve, retryMs));
             urlIndex--;
             continue;
@@ -211,15 +236,15 @@ export class AntigravityExecutor extends BaseExecutor {
             retryAttemptsByUrl[urlIndex]++;
             // Exponential backoff: 2s, 4s, 8s...
             const backoffMs = Math.min(1000 * (2 ** retryAttemptsByUrl[urlIndex]), MAX_RETRY_AFTER_MS);
-            log?.debug?.("RETRY", `429 auto retry ${retryAttemptsByUrl[urlIndex]}/${MAX_AUTO_RETRIES} after ${backoffMs/1000}s`);
+            log?.debug?.("RETRY", `429 auto retry ${retryAttemptsByUrl[urlIndex]}/${MAX_AUTO_RETRIES} after ${backoffMs / 1000}s`);
             await new Promise(resolve => setTimeout(resolve, backoffMs));
             urlIndex--;
             continue;
           }
 
-          log?.debug?.("RETRY", `${response.status}, Retry-After ${retryMs ? `too long (${Math.ceil(retryMs/1000)}s)` : 'missing'}, trying fallback`);
+          log?.debug?.("RETRY", `${response.status}, Retry-After ${retryMs ? `too long (${Math.ceil(retryMs / 1000)}s)` : 'missing'}, trying fallback`);
           lastStatus = response.status;
-          
+
           if (urlIndex + 1 < fallbackCount) {
             continue;
           }