fix: Replace broken web OAuth with manual token entry for Antigravity

- Removed Google OAuth popup flow (invalid_client error)
- Added manual access token input option
- Added instructions to use SDK mode with antigravity plugin (recommended)
- Added copy button for CLI command

packages/ui/src/components/settings/AntigravitySettings.tsx

@@ -1,5 +1,5 @@
 import { Component, createSignal, onMount, For, Show } from 'solid-js'
-import { Rocket, CheckCircle, XCircle, Loader, Sparkles, LogIn, LogOut, Shield } from 'lucide-solid'
+import { Rocket, CheckCircle, XCircle, Loader, Sparkles, Key, LogOut, Shield, Terminal, Copy, ExternalLink } from 'lucide-solid'
 import { getUserScopedKey } from '../../lib/user-storage'
 
 interface AntigravityModel {
@@ -22,15 +22,16 @@ interface AntigravityToken {
 }
 
 const ANTIGRAVITY_TOKEN_KEY = "antigravity_oauth_token"
-const GOOGLE_OAUTH_CLIENT_ID = "782068742485-pf45b4gldtk7q847g3v5ercqfl31nkud.apps.googleusercontent.com" // Antigravity/Gemini CLI client
 
 const AntigravitySettings: Component = () => {
     const [models, setModels] = createSignal<AntigravityModel[]>([])
     const [isLoading, setIsLoading] = createSignal(true)
     const [connectionStatus, setConnectionStatus] = createSignal<'idle' | 'testing' | 'connected' | 'failed'>('idle')
     const [authStatus, setAuthStatus] = createSignal<'unknown' | 'authenticated' | 'unauthenticated'>('unknown')
-    const [isAuthenticating, setIsAuthenticating] = createSignal(false)
     const [error, setError] = createSignal<string | null>(null)
+    const [showTokenInput, setShowTokenInput] = createSignal(false)
+    const [tokenInput, setTokenInput] = createSignal('')
+    const [copied, setCopied] = createSignal(false)
 
     // Check stored token on mount
     onMount(async () => {
@@ -100,104 +101,45 @@ const AntigravitySettings: Component = () => {
         }
     }
 
-    const startGoogleOAuth = async () => {
+    const handleTokenSubmit = () => {
-        setIsAuthenticating(true)
+        const token = tokenInput().trim()
-        setError(null)
+        if (!token) {
+            setError('Please enter a valid token')
+            return
+        }
 
         try {
-            // Open Google OAuth in a new window
+            const tokenData: AntigravityToken = {
-            const redirectUri = `${window.location.origin}/auth/antigravity/callback`
+                access_token: token,
-            const scope = encodeURIComponent("openid email profile https://www.googleapis.com/auth/cloud-platform")
+                expires_in: 3600, // 1 hour default
-            const state = crypto.randomUUID()
+                created_at: Date.now()
-
-            // Store state for verification
-            window.localStorage.setItem('antigravity_oauth_state', state)
-
-            const authUrl = `https://accounts.google.com/o/oauth2/v2/auth?` +
-                `client_id=${GOOGLE_OAUTH_CLIENT_ID}&` +
-                `redirect_uri=${encodeURIComponent(redirectUri)}&` +
-                `response_type=token&` +
-                `scope=${scope}&` +
-                `state=${state}&` +
-                `prompt=consent`
-
-            // Open popup
-            const width = 500
-            const height = 600
-            const left = (window.screen.width - width) / 2
-            const top = (window.screen.height - height) / 2
-
-            const popup = window.open(
-                authUrl,
-                'antigravity-oauth',
-                `width=${width},height=${height},left=${left},top=${top}`
-            )
-
-            if (!popup) {
-                throw new Error('Failed to open authentication window. Please allow popups.')
             }
 
-            // Poll for token in URL hash
+            window.localStorage.setItem(
-            const checkClosed = setInterval(() => {
+                getUserScopedKey(ANTIGRAVITY_TOKEN_KEY),
-                try {
+                JSON.stringify(tokenData)
-                    if (popup.closed) {
+            )
-                        clearInterval(checkClosed)
-                        setIsAuthenticating(false)
-                        checkAuthStatus()
-                        loadModels()
-                    } else {
-                        // Check if we can access the popup location (same origin after redirect)
-                        const hash = popup.location.hash
-                        if (hash && hash.includes('access_token')) {
-                            const params = new URLSearchParams(hash.substring(1))
-                            const accessToken = params.get('access_token')
-                            const expiresIn = parseInt(params.get('expires_in') || '3600', 10)
 
-                            if (accessToken) {
+            setAuthStatus('authenticated')
-                                const token: AntigravityToken = {
+            setShowTokenInput(false)
-                                    access_token: accessToken,
+            setTokenInput('')
-                                    expires_in: expiresIn,
+            setError(null)
-                                    created_at: Date.now()
+            loadModels()
-                                }
+        } catch (err) {
-
+            setError('Failed to save token')
-                                window.localStorage.setItem(
-                                    getUserScopedKey(ANTIGRAVITY_TOKEN_KEY),
-                                    JSON.stringify(token)
-                                )
-
-                                popup.close()
-                                clearInterval(checkClosed)
-                                setIsAuthenticating(false)
-                                setAuthStatus('authenticated')
-                                loadModels()
-                            }
-                        }
-                    }
-                } catch (e) {
-                    // Cross-origin error - popup is on Google's domain, still waiting
-                }
-            }, 500)
-
-            // Cleanup after 5 minutes
-            setTimeout(() => {
-                clearInterval(checkClosed)
-                if (!popup.closed) {
-                    popup.close()
-                }
-                setIsAuthenticating(false)
-            }, 300000)
-
-        } catch (err: any) {
-            console.error('OAuth error:', err)
-            setError(err.message || 'Authentication failed')
-            setIsAuthenticating(false)
         }
     }
 
     const signOut = () => {
         window.localStorage.removeItem(getUserScopedKey(ANTIGRAVITY_TOKEN_KEY))
         setAuthStatus('unauthenticated')
-        setModels([])
+    }
+
+    const copyCommand = async () => {
+        const command = 'npx opencode-antigravity-auth login'
+        await navigator.clipboard.writeText(command)
+        setCopied(true)
+        setTimeout(() => setCopied(false), 2000)
     }
 
     const formatNumber = (num: number): string => {
@@ -223,7 +165,7 @@ const AntigravitySettings: Component = () => {
                     </div>
                     <div>
                         <h2 class="text-xl font-semibold text-white">Antigravity</h2>
-                        <p class="text-sm text-zinc-400">Premium models via Google OAuth</p>
+                        <p class="text-sm text-zinc-400">Premium models via Google authentication</p>
                     </div>
                 </div>
 
@@ -254,66 +196,118 @@ const AntigravitySettings: Component = () => {
                 <div class="flex items-start gap-3">
                     <Sparkles class="w-5 h-5 text-purple-400 mt-0.5" />
                     <div>
-                        <h3 class="font-semibold text-purple-300 mb-1">Premium AI Models via Google</h3>
+                        <h3 class="font-semibold text-purple-300 mb-1">Premium AI Models</h3>
                         <p class="text-sm text-zinc-300">
                             Antigravity provides access to Gemini 3 Pro/Flash, Claude Sonnet 4.5, Claude Opus 4.5,
-                            and GPT-OSS 120B through Google's rate limits. Sign in with your Google account to get started.
+                            and GPT-OSS 120B through Google's infrastructure.
                         </p>
                     </div>
                 </div>
             </div>
 
             {/* Authentication Section */}
-            <div class="bg-zinc-900/50 border border-zinc-800 rounded-xl p-4">
+            <div class="bg-zinc-900/50 border border-zinc-800 rounded-xl p-4 space-y-4">
                 <div class="flex items-center justify-between">
                     <div class="flex items-center gap-3">
                         <Shield class="w-5 h-5 text-zinc-400" />
                         <div>
-                            <h4 class="font-medium text-white">Google OAuth Authentication</h4>
+                            <h4 class="font-medium text-white">Authentication</h4>
                             <p class="text-xs text-zinc-500">
                                 {authStatus() === 'authenticated'
-                                    ? 'You are signed in and can use Antigravity models'
+                                    ? 'Token configured - you can use Antigravity models'
-                                    : 'Sign in with Google to access premium models'}
+                                    : 'Configure authentication to access premium models'}
                             </p>
                         </div>
                     </div>
 
-                    <Show when={authStatus() === 'unauthenticated'}>
-                        <button
-                            onClick={startGoogleOAuth}
-                            disabled={isAuthenticating()}
-                            class="flex items-center gap-2 px-4 py-2 bg-purple-600 hover:bg-purple-500 disabled:bg-purple-600/50 text-white rounded-lg transition-colors"
-                        >
-                            {isAuthenticating() ? (
-                                <>
-                                    <Loader class="w-4 h-4 animate-spin" />
-                                    Signing in...
-                                </>
-                            ) : (
-                                <>
-                                    <LogIn class="w-4 h-4" />
-                                    Sign in with Google
-                                </>
-                            )}
-                        </button>
-                    </Show>
-
                     <Show when={authStatus() === 'authenticated'}>
                         <div class="flex items-center gap-3">
                             <span class="flex items-center gap-2 px-3 py-1.5 bg-emerald-500/20 text-emerald-400 rounded-lg text-sm">
                                 <CheckCircle class="w-4 h-4" />
-                                Authenticated
+                                Configured
                             </span>
                             <button
                                 onClick={signOut}
                                 class="flex items-center gap-2 px-3 py-1.5 text-sm text-zinc-400 hover:text-white bg-zinc-800 hover:bg-zinc-700 rounded-lg transition-colors"
                             >
                                 <LogOut class="w-4 h-4" />
-                                Sign out
+                                Clear
                             </button>
                         </div>
                     </Show>
                 </div>
+
+                <Show when={authStatus() === 'unauthenticated'}>
+                    {/* SDK Mode Instructions */}
+                    <div class="bg-blue-500/5 border border-blue-500/20 rounded-lg p-4 space-y-3">
+                        <div class="flex items-center gap-2 text-blue-400">
+                            <Terminal class="w-4 h-4" />
+                            <span class="font-medium text-sm">Recommended: Use OpenCode SDK Mode</span>
+                        </div>
+                        <p class="text-xs text-zinc-400">
+                            For the best experience, switch to OpenCode SDK mode in General settings.
+                            The Antigravity plugin handles authentication automatically via Google OAuth.
+                        </p>
+                        <div class="flex items-center gap-2">
+                            <code class="flex-1 px-3 py-2 bg-zinc-900 rounded text-xs font-mono text-zinc-300">
+                                npx opencode-antigravity-auth login
+                            </code>
+                            <button
+                                onClick={copyCommand}
+                                class="p-2 text-zinc-400 hover:text-white bg-zinc-800 hover:bg-zinc-700 rounded transition-colors"
+                                title="Copy command"
+                            >
+                                {copied() ? <CheckCircle class="w-4 h-4 text-emerald-400" /> : <Copy class="w-4 h-4" />}
+                            </button>
+                        </div>
+                    </div>
+
+                    {/* Manual Token Entry */}
+                    <div class="border-t border-zinc-800 pt-4">
+                        <Show when={!showTokenInput()}>
+                            <button
+                                onClick={() => setShowTokenInput(true)}
+                                class="flex items-center gap-2 text-sm text-zinc-400 hover:text-white transition-colors"
+                            >
+                                <Key class="w-4 h-4" />
+                                Or enter access token manually...
+                            </button>
+                        </Show>
+
+                        <Show when={showTokenInput()}>
+                            <div class="space-y-3">
+                                <label class="block text-sm font-medium text-zinc-300">
+                                    Access Token
+                                </label>
+                                <div class="flex gap-2">
+                                    <input
+                                        type="password"
+                                        value={tokenInput()}
+                                        onInput={(e) => setTokenInput(e.currentTarget.value)}
+                                        placeholder="Paste your Google OAuth access token..."
+                                        class="flex-1 px-3 py-2 bg-zinc-900 border border-zinc-700 rounded-lg text-sm text-white placeholder-zinc-500 focus:outline-none focus:border-purple-500"
+                                    />
+                                    <button
+                                        onClick={handleTokenSubmit}
+                                        class="px-4 py-2 bg-purple-600 hover:bg-purple-500 text-white rounded-lg text-sm transition-colors"
+                                    >
+                                        Save
+                                    </button>
+                                    <button
+                                        onClick={() => { setShowTokenInput(false); setTokenInput(''); }}
+                                        class="px-4 py-2 bg-zinc-800 hover:bg-zinc-700 text-zinc-400 rounded-lg text-sm transition-colors"
+                                    >
+                                        Cancel
+                                    </button>
+                                </div>
+                                <p class="text-xs text-zinc-500">
+                                    You can get an access token by running the Antigravity auth plugin in a terminal,
+                                    or by extracting it from an authenticated Google Cloud session.
+                                </p>
+                            </div>
+                        </Show>
+                    </div>
+                </Show>
             </div>
 
             {/* Error Display */}
@@ -391,21 +385,9 @@ const AntigravitySettings: Component = () => {
                     </div>
                 </Show>
 
-                <Show when={!isLoading() && models().length === 0 && authStatus() === 'authenticated'}>
+                <Show when={!isLoading() && models().length === 0}>
                     <div class="text-center py-12 text-zinc-500">
-                        <p>No models available at this time.</p>
+                        <p>Models will be available after configuration.</p>
-                        <button
-                            onClick={loadModels}
-                            class="mt-4 px-4 py-2 text-sm bg-purple-500/20 text-purple-400 hover:bg-purple-500/30 rounded-lg transition-colors"
-                        >
-                            Try Again
-                        </button>
-                    </div>
-                </Show>
-
-                <Show when={!isLoading() && models().length === 0 && authStatus() === 'unauthenticated'}>
-                    <div class="text-center py-12 text-zinc-500">
-                        <p>Sign in with Google to see available models.</p>
                     </div>
                 </Show>
             </div>
@@ -414,13 +396,26 @@ const AntigravitySettings: Component = () => {
             <div class="bg-zinc-900/50 border border-zinc-800 rounded-xl p-4">
                 <h4 class="font-medium text-white mb-2">How to Use</h4>
                 <ul class="text-sm text-zinc-400 space-y-1">
-                    <li>• Sign in with your Google account above</li>
+                    <li>• <strong>SDK Mode (Recommended):</strong> Switch to OpenCode binary mode and install the antigravity auth plugin</li>
+                    <li>• <strong>Native Mode:</strong> Enter your access token manually above</li>
                     <li>• Select any Antigravity model from the model picker in chat</li>
                     <li>• Models include Gemini 3, Claude Sonnet/Opus 4.5, and GPT-OSS</li>
                     <li>• Thinking-enabled models show step-by-step reasoning</li>
-                    <li>• Uses Google's rate limits for maximum throughput</li>
                 </ul>
             </div>
+
+            {/* Plugin Link */}
+            <div class="flex justify-center">
+                <a
+                    href="https://github.com/NoeFabris/opencode-antigravity-auth"
+                    target="_blank"
+                    rel="noopener noreferrer"
+                    class="flex items-center gap-2 text-sm text-purple-400 hover:text-purple-300 transition-colors"
+                >
+                    <ExternalLink class="w-4 h-4" />
+                    View Antigravity Auth Plugin on GitHub
+                </a>
+            </div>
         </div>
     )
 }