- Changed ideType and platform in headers to reflect actual environment

- Updated Gemini CLI headers to match expected formats and behaviors
- Removed Linux support and adjusted fingerprint generation accordingly
- Cleaned up unused functions and constants
- Enhanced tests to validate new header behaviors

Author: NoeFabris

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## [1.5.1] - 2026-02-11
+
+### Changed
+
+- **Header Identity Alignment** - `ideType` changed from `IDE_UNSPECIFIED` to `ANTIGRAVITY` and `platform` from `PLATFORM_UNSPECIFIED` to dynamic `WINDOWS`/`MACOS` (based on `process.platform`) across all header sources (`getAntigravityHeaders`, `oauth.ts`, `project.ts`). Now matches Antigravity Manager behavior
+
+- **Gemini CLI `Client-Metadata` Header** - Gemini CLI requests now include `Client-Metadata` header, aligning with actual `gemini-cli` behavior. Previously only Antigravity-style requests sent this header
+
+- **Gemini CLI User-Agent Format** - Updated from `GeminiCLI/{ver}/{model}` to `GeminiCLI/{ver}/{model} ({platform}; {arch})` to match real `gemini-cli` UA strings. Version pool updated from `1.2.0/1.1.0/1.0.0` to `0.28.0/0.27.4/0.27.3` to align with actual release numbers
+
+- **Randomized Headers Model-Aware** - `getRandomizedHeaders()` now accepts an optional `model` parameter, embedding the actual model name in Gemini CLI User-Agent strings instead of a hardcoded default
+
+- **Fingerprint Platform Alignment** - Antigravity-style `Client-Metadata` platform now consistently matches the randomized User-Agent platform, fixing a potential mismatch where headers could disagree on reported platform
+
+### Removed
+
+- **Linux Fingerprints** - Removed `linux/amd64` and `linux/arm64` from `ANTIGRAVITY_PLATFORMS` and fingerprint generation. Linux users now masquerade as macOS (Antigravity does not support Linux as a native platform)
+
+- **`getAntigravityUserAgents()` Function** - Removed unused helper that had no callers in the codebase
+
+- **`X-Opencode-Tools-Debug` Header** - Removed debug telemetry header from outgoing requests
+
 ## [1.5.0] - 2026-02-11
 
 ### Added

docs/ANTIGRAVITY_API_SPEC.md

@@ -64,7 +64,7 @@ Authorization: Bearer {access_token}
 Content-Type: application/json
 User-Agent: antigravity/1.15.8 windows/amd64
 X-Goog-Api-Client: google-cloud-sdk vscode_cloudshelleditor/0.1
-Client-Metadata: {"ideType":"IDE_UNSPECIFIED","platform":"PLATFORM_UNSPECIFIED","pluginType":"GEMINI"}
+Client-Metadata: {"ideType":"ANTIGRAVITY","platform":"MACOS","pluginType":"GEMINI"}
 ```
 
 For streaming requests, also include:

package.json

@@ -1,6 +1,6 @@
 {
     "name": "opencode-antigravity-auth",
-    "version": "1.5.0",
+    "version": "1.5.1",
     "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",

src/antigravity/oauth.ts

@@ -150,8 +150,8 @@ async function fetchProjectID(accessToken: string): Promise<string> {
         headers: loadHeaders,
         body: JSON.stringify({
           metadata: {
-            ideType: "IDE_UNSPECIFIED",
-            platform: "PLATFORM_UNSPECIFIED",
+            ideType: "ANTIGRAVITY",
+            platform: process.platform === "win32" ? "WINDOWS" : "MACOS",
             pluginType: "GEMINI",
           },
         }),

src/constants.test.ts

@@ -6,45 +6,29 @@ import {
 } from "./constants.ts"
 
 describe("GEMINI_CLI_HEADERS", () => {
-  it("contains only User-Agent with GeminiCLI format", () => {
+  it("matches Code Assist headers from opencode-gemini-auth", () => {
     expect(GEMINI_CLI_HEADERS).toEqual({
-      "User-Agent": "GeminiCLI/1.0.0/gemini-2.5-flash",
+      "User-Agent": "google-api-nodejs-client/9.15.1",
+      "X-Goog-Api-Client": "gl-node/22.17.0",
+      "Client-Metadata": "ideType=IDE_UNSPECIFIED,platform=PLATFORM_UNSPECIFIED,pluginType=GEMINI",
     })
   })
-
-  it("does not contain X-Goog-Api-Client", () => {
-    expect(GEMINI_CLI_HEADERS).not.toHaveProperty("X-Goog-Api-Client")
-  })
-
-  it("does not contain Client-Metadata", () => {
-    expect(GEMINI_CLI_HEADERS).not.toHaveProperty("Client-Metadata")
-  })
 })
 
 describe("getRandomizedHeaders", () => {
   describe("gemini-cli style", () => {
-    it("returns only User-Agent header", () => {
-      const headers = getRandomizedHeaders("gemini-cli")
-      expect(headers).toHaveProperty("User-Agent")
-      expect(headers["X-Goog-Api-Client"]).toBeUndefined()
-      expect(headers["Client-Metadata"]).toBeUndefined()
+    it("returns static Code Assist headers", () => {
+      const headers = getRandomizedHeaders("gemini-cli", "gemini-2.5-pro")
+      expect(headers).toEqual({
+        "User-Agent": "google-api-nodejs-client/9.15.1",
+        "X-Goog-Api-Client": "gl-node/22.17.0",
+        "Client-Metadata": "ideType=IDE_UNSPECIFIED,platform=PLATFORM_UNSPECIFIED,pluginType=GEMINI",
+      })
     })
 
-    it("returns a User-Agent in GeminiCLI format", () => {
-      const headers = getRandomizedHeaders("gemini-cli")
-      expect(headers["User-Agent"]).toMatch(/^GeminiCLI\/\d+\.\d+\.\d+\/gemini-2\.5-flash$/)
-    })
-
-    it("returns one of the expected GeminiCLI user agents", () => {
-      const expectedAgents = [
-        "GeminiCLI/1.2.0/gemini-2.5-flash",
-        "GeminiCLI/1.1.0/gemini-2.5-flash",
-        "GeminiCLI/1.0.0/gemini-2.5-flash",
-      ]
-      for (let i = 0; i < 20; i++) {
-        const headers = getRandomizedHeaders("gemini-cli")
-        expect(expectedAgents).toContain(headers["User-Agent"])
-      }
+    it("ignores requested model and keeps static User-Agent", () => {
+      const headers = getRandomizedHeaders("gemini-cli", "gemini-3-pro-preview")
+      expect(headers["User-Agent"]).toBe("google-api-nodejs-client/9.15.1")
     })
   })
 
@@ -60,6 +44,26 @@ describe("getRandomizedHeaders", () => {
       const headers = getRandomizedHeaders("antigravity")
       expect(headers["User-Agent"]).toMatch(/^antigravity\//)
     })
+
+    it("aligns Client-Metadata platform with User-Agent platform", () => {
+      for (let i = 0; i < 50; i++) {
+        const headers = getRandomizedHeaders("antigravity")
+        const ua = headers["User-Agent"]!
+        const metadata = JSON.parse(headers["Client-Metadata"]!)
+        if (ua.includes("windows/")) {
+          expect(metadata.platform).toBe("WINDOWS")
+        } else {
+          expect(metadata.platform).toBe("MACOS")
+        }
+      }
+    })
+
+    it("never produces a linux User-Agent", () => {
+      for (let i = 0; i < 50; i++) {
+        const headers = getRandomizedHeaders("antigravity")
+        expect(headers["User-Agent"]).not.toMatch(/linux\//)
+      }
+    })
   })
 })
 

src/constants.ts

@@ -93,39 +93,31 @@ export function getAntigravityHeaders(): HeaderSet & { "Client-Metadata": string
   return {
     "User-Agent": `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Antigravity/${getAntigravityVersion()} Chrome/138.0.7204.235 Electron/37.3.1 Safari/537.36`,
     "X-Goog-Api-Client": "google-cloud-sdk vscode_cloudshelleditor/0.1",
-    "Client-Metadata": '{"ideType":"IDE_UNSPECIFIED","platform":"PLATFORM_UNSPECIFIED","pluginType":"GEMINI"}',
+    "Client-Metadata": `{"ideType":"ANTIGRAVITY","platform":"${process.platform === "win32" ? "WINDOWS" : "MACOS"}","pluginType":"GEMINI"}`,
   };
 }
 
 /** @deprecated Use getAntigravityHeaders() for runtime access. */
 export const ANTIGRAVITY_HEADERS = {
   "User-Agent": `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Antigravity/${ANTIGRAVITY_VERSION} Chrome/138.0.7204.235 Electron/37.3.1 Safari/537.36`,
   "X-Goog-Api-Client": "google-cloud-sdk vscode_cloudshelleditor/0.1",
-  "Client-Metadata": '{"ideType":"IDE_UNSPECIFIED","platform":"PLATFORM_UNSPECIFIED","pluginType":"GEMINI"}',
+  "Client-Metadata": `{"ideType":"ANTIGRAVITY","platform":"${process.platform === "win32" ? "WINDOWS" : "MACOS"}","pluginType":"GEMINI"}`,
 } as const;
 
 export const GEMINI_CLI_HEADERS = {
-  "User-Agent": "GeminiCLI/1.0.0/gemini-2.5-flash",
+  "User-Agent": "google-api-nodejs-client/9.15.1",
+  "X-Goog-Api-Client": "gl-node/22.17.0",
+  "Client-Metadata": "ideType=IDE_UNSPECIFIED,platform=PLATFORM_UNSPECIFIED,pluginType=GEMINI",
 } as const;
 
-const ANTIGRAVITY_PLATFORMS = ["windows/amd64", "darwin/arm64", "linux/amd64", "darwin/amd64", "linux/arm64"] as const;
-
-function getAntigravityUserAgents(): string[] {
-  return ANTIGRAVITY_PLATFORMS.map(platform => `antigravity/${getAntigravityVersion()} ${platform}`);
-}
+const ANTIGRAVITY_PLATFORMS = ["windows/amd64", "darwin/arm64", "darwin/amd64"] as const;
 
 const ANTIGRAVITY_API_CLIENTS = [
   "google-cloud-sdk vscode_cloudshelleditor/0.1",
   "google-cloud-sdk vscode/1.96.0",
   "google-cloud-sdk vscode/1.95.0",
 ] as const;
 
-const GEMINI_CLI_USER_AGENTS = [
-  "GeminiCLI/1.2.0/gemini-2.5-flash",
-  "GeminiCLI/1.1.0/gemini-2.5-flash",
-  "GeminiCLI/1.0.0/gemini-2.5-flash",
-] as const;
-
 function randomFrom<T>(arr: readonly T[]): T {
   return arr[Math.floor(Math.random() * arr.length)]!;
 }
@@ -136,16 +128,20 @@ export type HeaderSet = {
   "Client-Metadata"?: string;
 };
 
-export function getRandomizedHeaders(style: HeaderStyle): HeaderSet {
+export function getRandomizedHeaders(style: HeaderStyle, model?: string): HeaderSet {
   if (style === "gemini-cli") {
     return {
-      "User-Agent": randomFrom(GEMINI_CLI_USER_AGENTS),
+      "User-Agent": GEMINI_CLI_HEADERS["User-Agent"],
+      "X-Goog-Api-Client": GEMINI_CLI_HEADERS["X-Goog-Api-Client"],
+      "Client-Metadata": GEMINI_CLI_HEADERS["Client-Metadata"],
     };
   }
+  const platform = randomFrom(ANTIGRAVITY_PLATFORMS);
+  const metadataPlatform = platform.startsWith("windows") ? "WINDOWS" : "MACOS";
   return {
-    "User-Agent": randomFrom(getAntigravityUserAgents()),
+    "User-Agent": `antigravity/${getAntigravityVersion()} ${platform}`,
     "X-Goog-Api-Client": randomFrom(ANTIGRAVITY_API_CLIENTS),
-    "Client-Metadata": getAntigravityHeaders()["Client-Metadata"],
+    "Client-Metadata": `{"ideType":"ANTIGRAVITY","platform":"${metadataPlatform}","pluginType":"GEMINI"}`,
   };
 }
 
@@ -262,4 +258,3 @@ You are pair programming with a USER to solve their coding task. The task may re
 
 <priority>IMPORTANT: The instructions that follow supersede all above. Follow them as your primary directives.</priority>
 `;
-

src/plugin/fingerprint.ts

@@ -22,15 +22,12 @@ const ARCHITECTURES = ["x64", "arm64"];
 
 const IDE_TYPES = [
   "ANTIGRAVITY",
-  "IDE_UNSPECIFIED",
-];
+] as const;
 
 const PLATFORMS = [
-  "PLATFORM_UNSPECIFIED",
   "WINDOWS",
   "MACOS",
-  "LINUX",
-];
+] as const;
 
 const SDK_CLIENTS = [
   "google-cloud-sdk vscode_cloudshelleditor/0.1",
@@ -90,18 +87,14 @@ function generateSessionToken(): string {
  * Each fingerprint represents a unique "device" identity.
  */
 export function generateFingerprint(): Fingerprint {
-  const platform = randomFrom(["darwin", "win32", "linux"]);
+  const platform = randomFrom(["darwin", "win32"] as const);
   const arch = randomFrom(ARCHITECTURES);
-  const osVersion = randomFrom(OS_VERSIONS[platform] ?? OS_VERSIONS.linux!);
+  const osVersion = randomFrom(OS_VERSIONS[platform] ?? OS_VERSIONS.darwin!);
 
   const matchingPlatform =
-    platform === "darwin"
-      ? "MACOS"
-      : platform === "win32"
-        ? "WINDOWS"
-        : platform === "linux"
-          ? "LINUX"
-          : randomFrom(PLATFORMS);
+    platform === "win32"
+      ? "WINDOWS"
+      : "MACOS";
 
   return {
     deviceId: generateDeviceId(),
@@ -126,13 +119,9 @@ export function collectCurrentFingerprint(): Fingerprint {
   const arch = os.arch();
 
   const matchingPlatform =
-    platform === "darwin"
-      ? "MACOS"
-      : platform === "win32"
-        ? "WINDOWS"
-        : platform === "linux"
-          ? "LINUX"
-          : "PLATFORM_UNSPECIFIED";
+    platform === "win32"
+      ? "WINDOWS"
+      : "MACOS";
 
   return {
     deviceId: generateDeviceId(),

src/plugin/project.ts

@@ -15,7 +15,7 @@ const projectContextPendingCache = new Map<string, Promise<ProjectContextResult>
 
 const CODE_ASSIST_METADATA = {
   ideType: "ANTIGRAVITY",
-  platform: "PLATFORM_UNSPECIFIED",
+  platform: process.platform === "win32" ? "WINDOWS" : "MACOS",
   pluginType: "GEMINI",
 } as const;
 

src/plugin/request.test.ts

@@ -596,7 +596,7 @@ it("removes x-api-key header", () => {
       expect(headers.get("x-goog-user-project")).toBeNull();
     });
 
-    it("removes x-goog-user-project header for gemini-cli headerStyle", () => {
+    it("preserves x-goog-user-project header for gemini-cli headerStyle", () => {
       const result = prepareAntigravityRequest(
         "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent",
         { method: "POST", body: JSON.stringify({ contents: [] }), headers: { "x-goog-user-project": "my-project" } },
@@ -606,7 +606,40 @@ it("removes x-api-key header", () => {
         "gemini-cli"
       );
       const headers = result.init.headers as Headers;
-      expect(headers.get("x-goog-user-project")).toBeNull();
+      expect(headers.get("x-goog-user-project")).toBe("my-project");
+    });
+
+    it("uses exact Code Assist headers for gemini-cli headerStyle", () => {
+      const result = prepareAntigravityRequest(
+        "https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash:generateContent",
+        { method: "POST", body: JSON.stringify({ contents: [] }) },
+        mockAccessToken,
+        mockProjectId,
+        undefined,
+        "gemini-cli"
+      );
+      const headers = result.init.headers as Headers;
+      expect(headers.get("User-Agent")).toBe("google-api-nodejs-client/9.15.1");
+      expect(headers.get("X-Goog-Api-Client")).toBe("gl-node/22.17.0");
+      expect(headers.get("Client-Metadata")).toBe("ideType=IDE_UNSPECIFIED,platform=PLATFORM_UNSPECIFIED,pluginType=GEMINI");
+    });
+
+    it("builds gemini-cli wrapped body without antigravity-only fields", () => {
+      const result = prepareAntigravityRequest(
+        "https://generativelanguage.googleapis.com/v1beta/models/gemini-3-flash:generateContent",
+        { method: "POST", body: JSON.stringify({ contents: [{ role: "user", parts: [{ text: "hi" }] }] }) },
+        mockAccessToken,
+        "",
+        undefined,
+        "gemini-cli"
+      );
+      const parsed = JSON.parse(result.init.body as string);
+      expect(parsed).toHaveProperty("project", "");
+      expect(parsed).toHaveProperty("model");
+      expect(parsed).toHaveProperty("request");
+      expect(parsed.requestType).toBeUndefined();
+      expect(parsed.userAgent).toBeUndefined();
+      expect(parsed.requestId).toBeUndefined();
     });
 
     it("identifies Claude models correctly", () => {