1. User clicks "Sign in with Google" in Tauri app
2. signInSocial() sends request to /api/auth/sign-in/social with Platform header
3. Server middleware appends scheme callback to OAuth redirectURI:
   → /api/auth/callback/google?callbackURL=my-app://
4. Server returns Google OAuth URL; client opens it in default browser
5. User authenticates in browser; Google redirects to callback URL
6. Server middleware intercepts callbackURL with scheme prefix
7. Server redirects to /api/auth/callback/success?redirectTo=my-app://api/auth/callback/google?...
8. Success page HTML triggers: window.location.href = 'my-app://...'
9. OS deep link activates Tauri app
10. Client handleAuthDeepLink() calls authClient.$fetch() to process callback
11. Server validates OAuth code, creates session, sets cookie
12. onSuccess callback fires - auth complete

bun add @tauri-apps/api @tauri-apps/plugin-deep-link @tauri-apps/plugin-http @tauri-apps/plugin-os @tauri-apps/plugin-opener better-auth

{
  "plugins": {
    "deep-link": {
      "desktop": {
        "schemes": ["my-app"]
      }
    }
  }
}

import { betterAuth } from "better-auth"
import { tauri } from "@daveyplate/better-auth-tauri/plugin"

export const auth = betterAuth({
  // ... your existing config
  plugins: [
    tauri({
      scheme: "my-app",        // Must match tauri.conf.json and client
      callbackURL: "/",        // Where to redirect after auth (default: "/")
      successText: "Authentication successful! You can close this window.",
      successURL: undefined,   // Custom success page URL (gets ?redirectTo param)
      debugLogs: false,        // Enable server-side debug logging
    }),
  ],
})

// lib/auth-client.ts
import { isTauri } from "@tauri-apps/api/core"
import { fetch as tauriFetch } from "@tauri-apps/plugin-http"
import { platform } from "@tauri-apps/plugin-os"
import { createAuthClient } from "better-auth/react" // or "better-auth/client"

export const authClient = createAuthClient({
  fetchOptions: {
    customFetchImpl: (...params) =>
      isTauri() && platform() === "macos" && window.location.protocol === "tauri:"
        ? tauriFetch(...params)
        : fetch(...params)
  }
})

import { setupBetterAuthTauri } from "@daveyplate/better-auth-tauri"
import { authClient } from "./lib/auth-client"

const cleanup = setupBetterAuthTauri({
  authClient,
  scheme: "my-app",           // Must match server config
  debugLogs: false,
  mainWindowLabel: "main",    // Tauri window label (default: "main")
  onRequest: (href) => {
    console.log("Processing auth callback:", href)
  },
  onSuccess: (callbackURL) => {
    window.location.href = callbackURL || "/"
  },
  onError: (error) => {
    // error: { status: number, statusText: string, code?: string, message?: string }
    console.error("Auth failed:", error.status, error.statusText)
  },
})

// Call cleanup() when done (e.g., component unmount)

import { useBetterAuthTauri } from "@daveyplate/better-auth-tauri/react"
import { authClient } from "./lib/auth-client"

function App() {
  useBetterAuthTauri({
    authClient,
    scheme: "my-app",
    onSuccess: (callbackURL) => {
      navigate(callbackURL || "/")
    },
    onError: (error) => {
      toast.error(`Auth failed: ${error.statusText}`)
    },
  })

  return <YourApp />
}

<script>
  import { onMount, onDestroy } from "svelte"
  import { setupBetterAuthTauri } from "@daveyplate/better-auth-tauri"
  import { authClient } from "./lib/auth-client"
  import { goto } from "$app/navigation"

  let cleanup
  onMount(() => {
    cleanup = setupBetterAuthTauri({
      authClient,
      scheme: "my-app",
      onSuccess: (callbackURL) => goto(callbackURL || "/"),
      onError: (error) => console.error("Auth error:", error),
    })
  })
  onDestroy(() => cleanup?.())
</script>

import { signInSocial } from "@daveyplate/better-auth-tauri"
import { authClient } from "./lib/auth-client"

<button onClick={async () => {
  const { data, error } = await signInSocial({
    authClient,
    provider: "google",  // Any configured social provider
  })
  if (error) console.error("Social sign-in error:", error)
}}>
  Sign in with Google
</button>

@daveyplate/better-auth-tauri          → setupBetterAuthTauri, signInSocial, handleAuthDeepLink
@daveyplate/better-auth-tauri/react    → useBetterAuthTauri (React hook)
@daveyplate/better-auth-tauri/plugin   → tauri (server plugin factory)