refactor(oauth): add provider registry

packages/ai/src/utils/oauth/google-antigravity.ts

@@ -8,7 +8,11 @@
 
 import type { Server } from "http";
 import { generatePKCE } from "./pkce.js";
-import type { OAuthCredentials } from "./types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthProviderInterface } from "./types.js";
+
+type AntigravityCredentials = OAuthCredentials & {
+	projectId: string;
+};
 
 // Antigravity OAuth credentials (different from Gemini CLI)
 const decode = (s: string) => atob(s);
@@ -411,3 +415,26 @@ export async function loginAntigravity(
 		server.server.close();
 	}
 }
+
+export const antigravityOAuthProvider: OAuthProviderInterface = {
+	id: "google-antigravity",
+	name: "Antigravity (Gemini 3, Claude, GPT-OSS)",
+	usesCallbackServer: true,
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginAntigravity(callbacks.onAuth, callbacks.onProgress, callbacks.onManualCodeInput);
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		const creds = credentials as AntigravityCredentials;
+		if (!creds.projectId) {
+			throw new Error("Antigravity credentials missing projectId");
+		}
+		return refreshAntigravityToken(creds.refresh, creds.projectId);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		const creds = credentials as AntigravityCredentials;
+		return JSON.stringify({ token: creds.access, projectId: creds.projectId });
+	},
+};