This setup is more technical and you'll need to paste the following prompt, which includes full scaffolding, into Lovable to get good results:

Copy# Despia Native SDK - TikTok OAuth Integration Guide

Production ready implementation for Lovable + Supabase (Custom Provider)

---

## IMPORTANT: User Must Provide Credentials

Before implementing this guide, you MUST collect the following from the user:

| Required Value | Where to Get It | Example |
|----------------|-----------------|---------|
| TikTok Client Key | TikTok Developer Portal > Your App > App Info | `sbaw471ke91ficgwnn` |
| TikTok Client Secret | TikTok Developer Portal > Your App > App Info | `xxxxxxxxxxxxxxxxxxx` |
| App URL | Your Lovable project URL | `https://myapp.lovable.app` |
| Deeplink Scheme (native only) | Despia Dashboard | `myapp` |

**ASK THE USER FOR THESE VALUES BEFORE GENERATING ANY CODE.**

Without these values, the implementation will fail with errors like:
- "TikTok not configured"
- "client_key" error from TikTok
- Invalid redirect URI

Once the user provides these values:
1. Hardcode `TIKTOK_CLIENT_KEY` and `APP_URL` in `src/lib/tiktok-auth.ts`
2. Add `TIKTOK_CLIENT_KEY` and `TIKTOK_CLIENT_SECRET` to Supabase Edge Function secrets
3. Update the deeplink scheme in `LoginButton.tsx` and `NativeCallback.tsx`

---

## What This Does

This implements TikTok OAuth login that works in:
1. Web browsers - Standard OAuth flow
2. Native mobile apps - When your Lovable web app is wrapped with Despia SDK

### Why Custom Implementation?

TikTok is not natively supported by Supabase, so we need to:
1. Handle TikTok OAuth flow ourselves
2. Exchange authorization codes for tokens server-side
3. Create/authenticate Supabase users using TikTok identity

### TikTok OAuth Flow Overview

```
User clicks "Sign in with TikTok"
    -> Redirect to TikTok authorization page
    -> User authorizes your app
    -> TikTok redirects back with authorization code
    -> Server exchanges code for access token
    -> Server fetches TikTok user info
    -> Server creates/signs in Supabase user
    -> Return session tokens to client
```

---

## Architecture

### Web Flow

```
LoginButton.tsx
    -> getTikTokOAuthUrl() (frontend, uses hardcoded client key)
    -> Redirect to TikTok
    -> TikTok redirects to /auth?code=xxx
    -> Auth.tsx calls auth-tiktok-callback edge function
    -> Edge function does EVERYTHING:
       1. Exchange code for TikTok access token
       2. Fetch TikTok user info
       3. Create/find Supabase user
       4. Generate magic link + verify OTP = real session
       5. Return Supabase tokens
    -> Auth.tsx calls setSession() with tokens
    -> User logged in
```

### Native Flow (Despia WebView)

```
LoginButton.tsx
    -> getTikTokOAuthUrl() with is_native=true
    -> despia('oauth://?url=...') opens ASWebAuthenticationSession
    -> TikTok redirects to /native-callback?code=xxx
    -> NativeCallback.tsx calls auth-tiktok-callback edge function
    -> Edge function returns Supabase tokens
    -> NativeCallback.tsx redirects to deeplink with tokens
    -> Native app navigates to /auth?tokens
    -> Auth.tsx calls setSession() with tokens
    -> User logged in
```

---

## CRITICAL: Why This Works (Lessons Learned)

### WRONG: Manual JWT Creation

```typescript
// This WILL NOT WORK - creates "bad_jwt" errors
import * as jose from "jose";
const jwt = await new jose.SignJWT({ sub: userId, ... }).sign(secret);
```

Supabase tokens have specific claims, signatures, and internal state that manual JWTs don't have.

### CORRECT: Magic Link + OTP Verification

```typescript
// This creates REAL Supabase tokens that work everywhere
const { data: linkData } = await supabaseAdmin.auth.admin.generateLink({
  type: 'magiclink',
  email: userEmail,
});

const { data: sessionData } = await supabasePublic.auth.verifyOtp({
  token_hash: linkData.properties.hashed_token,
  type: 'email',  // Use 'email' type for verification (works with Supabase 2.39+)
});
// sessionData.session.access_token = real, working token!
```

**Note on verifyOtp type:** Use `type: 'email'` for Supabase JS v2.39+. Older versions may require `type: 'magiclink'`. If you get type errors, try switching between these values.

### Key Requirements

1. **Two Supabase clients** in the edge function:
   - `supabaseAdmin` (SUPABASE_SERVICE_ROLE_KEY) - for creating users, generating links
   - `supabasePublic` (SUPABASE_ANON_KEY) - for verifying OTP to create session
   - NOTE: Use `SUPABASE_ANON_KEY` not `SUPABASE_PUBLISHABLE_KEY`

2. **Always set `email_confirm: true`** when creating OAuth users

3. **Use `setSession()`** on the frontend, not just storing tokens

4. **Single edge function** - faster than multiple calls

---

## CRITICAL: Required Components

**FIRST: Ask the user for their TikTok credentials before generating any code.**

| Component | What It Does | Without It |
|-----------|--------------|------------|
| **User's TIKTOK_CLIENT_KEY** | Hardcoded in tiktok-auth.ts | "TikTok credentials not configured" error |
| **User's APP_URL** | Hardcoded in tiktok-auth.ts | Wrong redirect URI |
| auth-tiktok-callback | Single edge function - does everything | Can't complete login |
| LoginButton.tsx | Starts TikTok OAuth flow | Nothing happens on click |
| Auth.tsx | Handles web callback, sets session | Web login fails |
| NativeCallback.tsx | Handles native callback, closes browser | Native stuck in browser |

**Architecture simplified!** Only ONE edge function needed. It uses `generateLink()` + `verifyOtp()` to create real Supabase sessions.

---

## Complete File List

| # | File Path | Purpose |
|---|-----------|---------|
| 1 | supabase/functions/auth-tiktok-callback/index.ts | Single edge function - handles everything |
| 2 | src/lib/tiktok-auth.ts | TikTok auth helper functions + shared config |
| 3 | src/components/LoginButton.tsx | Login button - handles both flows |
| 4 | src/pages/Auth.tsx | OAuth callback (web) + login page |
| 5 | src/pages/NativeCallback.tsx | OAuth callback (native) |
| 6 | src/pages/NotFound.tsx | 404 page |
| 7 | src/App.tsx | Route configuration |
| 8 | supabase/config.toml | Edge function config |
| 9 | public/404.html | SPA fallback |
| 10 | src/components/SpaRedirector.tsx | Handle 404 redirect |
| 11 | public/_redirects | SPA routing (Netlify/Lovable) |

**Simplified!** Only ONE edge function needed - it handles code exchange, user creation, AND session generation in a single call.

---

## Step 1: Set Up TikTok Developer App

### In TikTok Developer Portal

1. Go to https://developers.tiktok.com/
2. Create a new app or use existing
3. Add "Login Kit" product
4. Configure OAuth settings:
   - **Redirect URI (Web)**: `https://YOUR-APP.lovable.app/auth`
   - **Redirect URI (Native)**: `https://YOUR-APP.lovable.app/native-callback`
5. Note your **Client Key** and **Client Secret**
6. Request scopes: `user.info.basic` (minimum required)

### Required Scopes

| Scope | What It Provides |
|-------|------------------|
| user.info.basic | Open ID, avatar, display name |
| user.info.profile | Bio, profile deep link (optional) |
| user.info.stats | Follower/following counts (optional) |

---

## Step 2: Add Environment Variables

### Frontend Configuration (Hardcoded)

The TikTok client key and APP_URL are configured directly in `src/lib/tiktok-auth.ts`. All other files import from there for consistency.

**You must ask the user for their TikTok Client Key and App URL, then hardcode them:**

```typescript
const TIKTOK_CLIENT_KEY = 'user_provided_key_here'; // e.g., 'sbaw471ke91ficgwnn'
const APP_URL = 'https://user-app.lovable.app';     // e.g., 'https://myapp.lovable.app'
```

**This is safe** because the client_key is public (it's visible in the OAuth URL that users see anyway).

### In Supabase Dashboard (Server-side Secrets)

Go to Project Settings > Edge Functions > Add secrets:

```
TIKTOK_CLIENT_KEY=user_provided_key
TIKTOK_CLIENT_SECRET=user_provided_secret
```

**Lovable Cloud automatically provides these Supabase secrets** - do NOT add them manually:

| Auto-provided Secret | Purpose |
|---------------------|---------|
| `SUPABASE_URL` | Your project's API URL |
| `SUPABASE_ANON_KEY` | Public key for client operations |
| `SUPABASE_SERVICE_ROLE_KEY` | Admin key for privileged operations |

**Common mistake**: Using `SUPABASE_PUBLISHABLE_KEY` instead of `SUPABASE_ANON_KEY` will cause "supabaseKey is required" errors.

---

## Step 3: Install Dependencies

```bash
npm install despia-native
```

---

## Step 4: Create TikTok Auth Callback Edge Function

File: `supabase/functions/auth-tiktok-callback/index.ts`

This single edge function handles EVERYTHING:
1. Exchanges the authorization code for TikTok tokens
2. Fetches user info from TikTok
3. Creates or finds the Supabase user
4. Generates a real Supabase session using magic link + OTP verification

**CRITICAL**: We use `generateLink()` + `verifyOtp()` instead of manual JWT creation. Manual JWTs will fail with "bad_jwt" errors!

```typescript
import { serve } from "https://deno.land/std@0.168.0/http/server.ts";
import { createClient } from "https://esm.sh/@supabase/supabase-js@2.39.0";

const corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Headers': 'authorization, x-client-info, apikey, content-type',
};

serve(async (req) => {
  // Handle CORS preflight
  if (req.method === 'OPTIONS') {
    return new Response(null, { headers: corsHeaders });
  }

  try {
    const { code, redirect_uri } = await req.json();

    if (!code) {
      return new Response(
        JSON.stringify({ error: 'Authorization code required' }),
        { status: 400, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
      );
    }

    const clientKey = Deno.env.get('TIKTOK_CLIENT_KEY')!;
    const clientSecret = Deno.env.get('TIKTOK_CLIENT_SECRET')!;
    const supabaseUrl = Deno.env.get('SUPABASE_URL')!;
    const serviceRoleKey = Deno.env.get('SUPABASE_SERVICE_ROLE_KEY')!;
    const anonKey = Deno.env.get('SUPABASE_ANON_KEY')!;
    
    // IMPORTANT: Lovable Cloud provides these automatically:
    // - SUPABASE_URL
    // - SUPABASE_ANON_KEY (NOT "SUPABASE_PUBLISHABLE_KEY")
    // - SUPABASE_SERVICE_ROLE_KEY
    // Using the wrong variable name will cause "supabaseKey is required" errors

    console.log('Step 1: Exchanging code for TikTok access token...');

    // ============================================
    // STEP 1: Exchange code for TikTok access token
    // ============================================
    const tokenResponse = await fetch('https://open.tiktokapis.com/v2/oauth/token/', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
      },
      body: new URLSearchParams({
        client_key: clientKey,
        client_secret: clientSecret,
        code: code,
        grant_type: 'authorization_code',
        redirect_uri: redirect_uri,
      }),
    });

    if (!tokenResponse.ok) {
      const errorText = await tokenResponse.text();
      console.error('TikTok token error:', errorText);
      return new Response(
        JSON.stringify({ error: 'Failed to exchange code', details: errorText }),
        { status: 400, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
      );
    }

    const tokenData = await tokenResponse.json();
    const accessToken = tokenData.access_token;
    const openId = tokenData.open_id;

    console.log('Step 2: Fetching TikTok user info...');

    // ============================================
    // STEP 2: Fetch user info from TikTok
    // ============================================
    const userInfoResponse = await fetch(
      'https://open.tiktokapis.com/v2/user/info/?fields=open_id,union_id,avatar_url,display_name',
      {
        headers: {
          'Authorization': `Bearer ${accessToken}`,
        },
      }
    );

    if (!userInfoResponse.ok) {
      const errorText = await userInfoResponse.text();
      console.error('TikTok user info error:', errorText);
      return new Response(
        JSON.stringify({ error: 'Failed to fetch user info' }),
        { status: 400, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
      );
    }

    const userInfoData = await userInfoResponse.json();
    const tiktokUser = userInfoData.data?.user;
    const displayName = tiktokUser?.display_name || 'TikTok User';
    const avatarUrl = tiktokUser?.avatar_url || '';

    console.log('Step 3: Creating/finding Supabase user...');

    // ============================================
    // STEP 3: Create or find Supabase user
    // ============================================
    
    // Admin client for privileged operations
    const supabaseAdmin = createClient(supabaseUrl, serviceRoleKey, {
      auth: { autoRefreshToken: false, persistSession: false }
    });

    // Public client for session verification
    const supabasePublic = createClient(supabaseUrl, anonKey);

    // Create deterministic email from TikTok's unique identifier
    const tiktokEmail = `${openId.toLowerCase()}@tiktok.oauth`;

    let userId: string;

    // Try to create user first
    const { data: createData, error: createError } = await supabaseAdmin.auth.admin.createUser({
      email: tiktokEmail,
      email_confirm: true,  // CRITICAL: Auto-confirm for OAuth users
      user_metadata: {
        tiktok_open_id: openId,
        display_name: displayName,
        avatar_url: avatarUrl,
        full_name: displayName,
        provider: 'tiktok'
      }
    });

    if (createError) {
      // User already exists - find them
      if (createError.message?.includes('already been registered')) {
        console.log('User exists, fetching...');
        const { data: existingUsers } = await supabaseAdmin.auth.admin.listUsers();
        const existingUser = existingUsers?.users.find(u => u.email === tiktokEmail);
        
        if (!existingUser) {
          return new Response(
            JSON.stringify({ error: 'User not found' }),
            { status: 400, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
          );
        }
        
        userId = existingUser.id;

        // Update user metadata with latest TikTok info
        await supabaseAdmin.auth.admin.updateUserById(userId, {
          user_metadata: {
            tiktok_open_id: openId,
            display_name: displayName,
            avatar_url: avatarUrl,
            full_name: displayName,
            provider: 'tiktok'
          }
        });
      } else {
        console.error('Failed to create user:', createError);
        return new Response(
          JSON.stringify({ error: 'Failed to create user', details: createError.message }),
          { status: 500, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
        );
      }
    } else {
      userId = createData.user.id;
    }

    console.log('Step 4: Generating Supabase session via magic link + OTP verification...');

    // ============================================
    // STEP 4: Generate real Supabase session
    // ============================================
    // 
    // CRITICAL: We use generateLink() + verifyOtp() instead of manual JWT creation
    // Manual JWTs will fail with "bad_jwt" errors!
    //

    const { data: linkData, error: linkError } = await supabaseAdmin.auth.admin.generateLink({
      type: 'magiclink',
      email: tiktokEmail,
    });

    if (linkError || !linkData) {
      console.error('Failed to generate magic link:', linkError);
      return new Response(
        JSON.stringify({ error: 'Failed to generate session' }),
        { status: 500, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
      );
    }

    // Verify the magic link token to create a real session
    // NOTE: Use 'email' type for Supabase 2.39+. If you get errors, try 'magiclink' instead.
    const { data: sessionData, error: sessionError } = await supabasePublic.auth.verifyOtp({
      token_hash: linkData.properties.hashed_token,
      type: 'email',
    });

    if (sessionError || !sessionData.session) {
      console.error('Failed to verify OTP:', sessionError);
      return new Response(
        JSON.stringify({ error: 'Failed to create session' }),
        { status: 500, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
      );
    }

    console.log('Success! User logged in:', userId);

    // Return tokens to frontend
    return new Response(
      JSON.stringify({
        access_token: sessionData.session.access_token,
        refresh_token: sessionData.session.refresh_token,
        expires_in: sessionData.session.expires_in,
        user: sessionData.user,
      }),
      { headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
    );

  } catch (error) {
    console.error('Error:', error);
    const message = error instanceof Error ? error.message : 'Unknown error';
    return new Response(
      JSON.stringify({ error: message }),
      { status: 500, headers: { ...corsHeaders, 'Content-Type': 'application/json' } }
    );
  }
});
```

---

## Step 5: Configure Edge Function

File: `supabase/config.toml`

```toml
[functions.auth-tiktok-callback]
verify_jwt = false
```

**Note**: We only need ONE edge function now. The `auth-tiktok-callback` function handles everything (code exchange, user creation, AND session generation) in a single call.

---

## Step 6: Create Database Tables (Optional)

Run this SQL in Supabase SQL Editor if you want to store TikTok profile data:

```sql
-- Optional: Profiles table for TikTok user data
CREATE TABLE IF NOT EXISTS profiles (
  id UUID PRIMARY KEY REFERENCES auth.users(id) ON DELETE CASCADE,
  tiktok_id TEXT UNIQUE,
  display_name TEXT,
  avatar_url TEXT,
  created_at TIMESTAMPTZ DEFAULT NOW(),
  updated_at TIMESTAMPTZ DEFAULT NOW()
);

-- RLS Policies
ALTER TABLE profiles ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users can view own profile"
  ON profiles FOR SELECT
  USING (auth.uid() = id);

CREATE POLICY "Users can update own profile"
  ON profiles FOR UPDATE
  USING (auth.uid() = id);
```

**Note**: The profiles table is optional. User data is also stored in `auth.users.user_metadata`.

---

## Step 7: Create TikTok Auth Helper

File: `src/lib/tiktok-auth.ts`

**IMPORTANT**: Replace the placeholder values below with the actual credentials provided by the user. This file exports `APP_URL` for use by other components.

```typescript
import { supabase } from '@/integrations/supabase/client';

// ============================================
// CONFIGURATION - REPLACE WITH USER'S VALUES
// ============================================
// ASK THE USER FOR THESE VALUES BEFORE IMPLEMENTING
export const TIKTOK_CLIENT_KEY = 'USER_PROVIDED_CLIENT_KEY'; // Get from user
export const APP_URL = 'https://USER_PROVIDED_APP.lovable.app'; // Get from user
// ============================================

export interface TikTokAuthResult {
  success: boolean;
  access_token?: string;
  refresh_token?: string;
  user?: any;
  error?: string;
}

/**
 * Generate TikTok OAuth URL
 * Client key is public (visible in OAuth URL anyway)
 */
export function getTikTokOAuthUrl(isNative: boolean, deeplinkScheme?: string): string | null {
  if (!TIKTOK_CLIENT_KEY || TIKTOK_CLIENT_KEY === 'USER_PROVIDED_CLIENT_KEY') {
    console.error('TikTok client key not configured. The developer must set the actual client key in src/lib/tiktok-auth.ts');
    return null;
  }

  // Generate state for CSRF protection
  const state = crypto.randomUUID();
  
  // Store state in sessionStorage for verification on callback
  // Wrapped in try-catch for private browsing mode compatibility
  try {
    sessionStorage.setItem(`tiktok_oauth_state_${state}`, JSON.stringify({
      state,
      is_native: isNative,
      deeplink_scheme: deeplinkScheme || null,
      created_at: new Date().toISOString(),
    }));
  } catch (e) {
    console.warn('sessionStorage not available (private browsing?), state validation will be skipped');
  }

  // Determine redirect URI based on flow type
  const redirectUri = isNative 
    ? `${APP_URL}/native-callback`
    : `${APP_URL}/auth`;

  // Build TikTok OAuth URL
  const params = new URLSearchParams({
    client_key: TIKTOK_CLIENT_KEY,
    response_type: 'code',
    scope: 'user.info.basic',
    redirect_uri: redirectUri,
    state: isNative && deeplinkScheme ? `${state}|${deeplinkScheme}` : state,
  });

  return `https://www.tiktok.com/v2/auth/authorize/?${params.toString()}`;
}

/**
 * Validate OAuth state parameter against stored value
 * Returns true if valid or if sessionStorage is unavailable
 */
export function validateOAuthState(state: string | null): boolean {
  if (!state) return false;
  
  // Extract the UUID part (before | if present)
  const stateParts = state.split('|');
  const stateUuid = stateParts[0];
  
  try {
    const stored = sessionStorage.getItem(`tiktok_oauth_state_${stateUuid}`);
    if (!stored) {
      console.warn('No stored state found - may have expired or sessionStorage unavailable');
      return true; // Allow if sessionStorage unavailable (private browsing)
    }
    
    const storedData = JSON.parse(stored);
    
    // Clean up the stored state
    sessionStorage.removeItem(`tiktok_oauth_state_${stateUuid}`);
    
    // Check if state is too old (10 minutes max)
    const createdAt = new Date(storedData.created_at);
    const now = new Date();
    const ageMinutes = (now.getTime() - createdAt.getTime()) / 1000 / 60;
    
    if (ageMinutes > 10) {
      console.error('OAuth state expired');
      return false;
    }
    
    return storedData.state === stateUuid;
  } catch (e) {
    console.warn('sessionStorage not available, skipping state validation');
    return true; // Allow if sessionStorage unavailable
  }
}

/**
 * Exchange authorization code for Supabase session
 * Single edge function call - handles everything server-side
 */
export async function exchangeTikTokCode(
  code: string,
  redirectUri: string
): Promise<TikTokAuthResult> {
  try {
    const { data, error } = await supabase.functions.invoke('auth-tiktok-callback', {
      body: { code, redirect_uri: redirectUri },
    });

    if (error) {
      console.error('Edge function error:', error);
      return { success: false, error: error.message };
    }

    if (!data?.access_token) {
      return { success: false, error: data?.error || 'No access token returned' };
    }

    return {
      success: true,
      access_token: data.access_token,
      refresh_token: data.refresh_token,
      user: data.user,
    };
  } catch (err) {
    console.error('Error exchanging TikTok code:', err);
    return {
      success: false,
      error: err instanceof Error ? err.message : 'Unknown error',
    };
  }
}

/**
 * Set Supabase session from tokens
 */
export async function setTikTokSession(
  accessToken: string,
  refreshToken: string
): Promise<boolean> {
  try {
    const { error } = await supabase.auth.setSession({
      access_token: accessToken,
      refresh_token: refreshToken,
    });

    if (error) {
      console.error('Failed to set session:', error);
      return false;
    }

    return true;
  } catch (err) {
    console.error('Error setting session:', err);
    return false;
  }
}
```

---

## Step 8: Create Login Button

File: `src/components/LoginButton.tsx`

```typescript
import { useState } from 'react';
import { Button } from '@/components/ui/button';
import despia from 'despia-native';
import { getTikTokOAuthUrl } from '@/lib/tiktok-auth';

interface LoginButtonProps {
  onError?: (error: string) => void;
}

const LoginButton = ({ onError }: LoginButtonProps) => {
  const [isLoading, setIsLoading] = useState(false);

  const handleTikTokLogin = async () => {
    // Detect if running in Despia native app
    const isNative = navigator.userAgent.toLowerCase().includes('despia');
    
    setIsLoading(true);

    try {
      // Generate TikTok OAuth URL (uses hardcoded client key)
      const oauthUrl = getTikTokOAuthUrl(
        isNative,
        isNative ? 'myapp' : undefined // CHANGE 'myapp' to your Despia app scheme
      );

      if (!oauthUrl) {
        onError?.('TikTok credentials not configured. Please provide your TikTok Client Key.');
        setIsLoading(false);
        return;
      }

      if (isNative) {
        // NATIVE FLOW
        // Open in ASWebAuthenticationSession (iOS) or Chrome Custom Tab (Android)
        // oauth:// prefix tells Despia to use secure browser session
        despia(`oauth://?url=${encodeURIComponent(oauthUrl)}`);
        // Note: Loading state will persist until user returns or cancels
      } else {
        // WEB FLOW
        // Redirect to TikTok in same window
        window.location.href = oauthUrl;
      }
    } catch (err) {
      console.error('Login error:', err);
      onError?.(err instanceof Error ? err.message : 'Login failed');
      setIsLoading(false);
    }
  };

  return (
    <Button
      onClick={handleTikTokLogin}
      disabled={isLoading}
      className="w-full bg-black hover:bg-gray-800 text-white"
    >
      {isLoading ? (
        <span className="flex items-center gap-2">
          <svg className="animate-spin h-4 w-4" viewBox="0 0 24 24">
            <circle
              className="opacity-25"
              cx="12"
              cy="12"
              r="10"
              stroke="currentColor"
              strokeWidth="4"
              fill="none"
            />
            <path
              className="opacity-75"
              fill="currentColor"
              d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z"
            />
          </svg>
          Connecting...
        </span>
      ) : (
        <span className="flex items-center gap-2">
          {/* TikTok Icon */}
          <svg className="h-5 w-5" viewBox="0 0 24 24" fill="currentColor">
            <path d="M19.59 6.69a4.83 4.83 0 01-3.77-4.25V2h-3.45v13.67a2.89 2.89 0 01-5.2 1.74 2.89 2.89 0 012.31-4.64 2.93 2.93 0 01.88.13V9.4a6.84 6.84 0 00-1-.05A6.33 6.33 0 005 20.1a6.34 6.34 0 0010.86-4.43v-7a8.16 8.16 0 004.77 1.52v-3.4a4.85 4.85 0 01-1-.1z" />
          </svg>
          Sign in with TikTok
        </span>
      )}
    </Button>
  );
};

export default LoginButton;
```

---

## Step 9: Create Auth Page (Web Callback)

File: `src/pages/Auth.tsx`

```typescript
import { useEffect, useState, useRef } from 'react';
import { useNavigate, useSearchParams } from 'react-router-dom';
import { supabase } from '@/integrations/supabase/client';
import { Button } from '@/components/ui/button';
import LoginButton from '@/components/LoginButton';
import { APP_URL, exchangeTikTokCode, setTikTokSession, validateOAuthState } from '@/lib/tiktok-auth';

const Auth = () => {
  const [searchParams] = useSearchParams();
  const navigate = useNavigate();
  const [error, setError] = useState<string | null>(null);
  const [showLogin, setShowLogin] = useState(false);
  const [isProcessing, setIsProcessing] = useState(false);
  const hasRun = useRef(false);

  useEffect(() => {
    if (hasRun.current) return;
    hasRun.current = true;

    const handleAuth = async () => {
      // Check if already logged in
      const { data: { session: existingSession } } = await supabase.auth.getSession();
      if (existingSession) {
        navigate('/', { replace: true });
        return;
      }

      // Check for TikTok authorization code
      const code = searchParams.get('code');
      const state = searchParams.get('state');
      const errorParam = searchParams.get('error');
      const errorDescription = searchParams.get('error_description');

      // Check for direct token params (from native callback deeplink)
      const accessToken = searchParams.get('access_token');
      const refreshToken = searchParams.get('refresh_token');

      // Handle errors
      if (errorParam) {
        setError(errorDescription || errorParam);
        return;
      }

      // Handle direct tokens (from native flow)
      if (accessToken) {
        setIsProcessing(true);
        const success = await setTikTokSession(accessToken, refreshToken || '');
        if (success) {
          navigate('/', { replace: true });
        } else {
          setError('Failed to set session');
        }
        return;
      }

      // Handle authorization code (web flow)
      if (code) {
        setIsProcessing(true);
        
        // Validate state parameter to prevent CSRF attacks
        if (!validateOAuthState(state)) {
          setError('Invalid or expired OAuth state. Please try again.');
          setIsProcessing(false);
          return;
        }
        
        const result = await exchangeTikTokCode(code, `${APP_URL}/auth`);
        
        if (!result.success) {
          setError(result.error || 'Authentication failed');
          setIsProcessing(false);
          return;
        }

        // Set session
        const success = await setTikTokSession(
          result.access_token!,
          result.refresh_token!
        );

        if (success) {
          navigate('/', { replace: true });
        } else {
          setError('Failed to complete login');
          setIsProcessing(false);
        }
        return;
      }

      // No code or tokens - show login button
      setShowLogin(true);
    };

    handleAuth();
  }, [searchParams, navigate]);

  if (error) {
    return (
      <div className="flex min-h-screen items-center justify-center bg-background p-4">
        <div className="w-full max-w-sm space-y-4">
          <div className="rounded-lg border border-destructive/50 bg-destructive/10 p-4 text-center">
            <h2 className="text-lg font-semibold text-destructive">Sign in failed</h2>
            <p className="mt-2 text-sm text-muted-foreground">{error}</p>
          </div>
          <Button onClick={() => { setError(null); setShowLogin(true); }} className="w-full">
            Try again
          </Button>
          <Button 
            variant="outline" 
            onClick={() => navigate('/', { replace: true })} 
            className="w-full"
          >
            Go to home
          </Button>
        </div>
      </div>
    );
  }

  if (showLogin) {
    return (
      <div className="flex min-h-screen items-center justify-center bg-background p-4">
        <div className="w-full max-w-sm space-y-6 text-center">
          <div>
            <h1 className="text-2xl font-bold">Welcome</h1>
            <p className="mt-2 text-muted-foreground">Sign in to continue</p>
          </div>
          <LoginButton onError={setError} />
        </div>
      </div>
    );
  }

  return (
    <div className="flex min-h-screen items-center justify-center bg-background p-4">
      <div className="text-center">
        <div className="mx-auto h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
        <p className="mt-4 text-sm text-muted-foreground">
          {isProcessing ? 'Completing sign in...' : 'Loading...'}
        </p>
      </div>
    </div>
  );
};

export default Auth;
```

---

## Step 10: Create Native Callback Page

File: `src/pages/NativeCallback.tsx`

```typescript
import { useEffect, useRef, useState } from 'react';
import { useSearchParams } from 'react-router-dom';
import { APP_URL, exchangeTikTokCode } from '@/lib/tiktok-auth';

const NativeCallback = () => {
  const [searchParams] = useSearchParams();
  const [error, setError] = useState<string | null>(null);
  const hasRun = useRef(false);

  useEffect(() => {
    if (hasRun.current) return;
    hasRun.current = true;

    const handleNativeCallback = async () => {
      // Get code and state from TikTok redirect
      const code = searchParams.get('code');
      const state = searchParams.get('state');
      const errorParam = searchParams.get('error');
      const errorDescription = searchParams.get('error_description');

      // Parse deeplink scheme from state (format: "uuid|scheme" or just "uuid")
      let deeplinkScheme = 'myapp'; // Default scheme - CHANGE to your Despia app scheme
      if (state && state.includes('|')) {
        const parts = state.split('|');
        deeplinkScheme = parts[1] || deeplinkScheme;
      }

      // Handle TikTok errors
      if (errorParam) {
        const errorUrl = `${deeplinkScheme}://oauth/auth?error=${encodeURIComponent(errorParam)}&error_description=${encodeURIComponent(errorDescription || '')}`;
        window.location.href = errorUrl;
        return;
      }

      if (!code) {
        setError('No authorization code received');
        return;
      }

      // Exchange code for tokens
      const result = await exchangeTikTokCode(code, `${APP_URL}/native-callback`);

      if (!result.success) {
        // Redirect to app with error
        const errorUrl = `${deeplinkScheme}://oauth/auth?error=${encodeURIComponent(result.error || 'unknown')}`;
        window.location.href = errorUrl;
        return;
      }

      // Build deeplink URL with tokens
      // Format: myapp://oauth/auth?access_token=xxx&refresh_token=yyy
      // - myapp:// = your app's deeplink scheme
      // - oauth/ = tells native code to close ASWebAuthenticationSession/Chrome Custom Tab
      // - auth = the path to navigate to in the WebView
      const params = new URLSearchParams();
      params.set('access_token', result.access_token!);
      if (result.refresh_token) {
        params.set('refresh_token', result.refresh_token);
      }

      const deeplinkUrl = `${deeplinkScheme}://oauth/auth?${params.toString()}`;

      console.log('Redirecting to deeplink:', deeplinkUrl);

      // This closes the ASWebAuthenticationSession / Chrome Custom Tab
      // and opens /auth?access_token=xxx in the WebView
      window.location.href = deeplinkUrl;
    };

    handleNativeCallback();
  }, [searchParams]);

  if (error) {
    return (
      <div className="flex min-h-screen items-center justify-center bg-background p-4">
        <div className="text-center">
          <p className="text-destructive">{error}</p>
        </div>
      </div>
    );
  }

  return (
    <div className="flex min-h-screen items-center justify-center bg-background p-4">
      <div className="text-center">
        <div className="mx-auto h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
        <p className="mt-4 text-sm text-muted-foreground">Completing sign in...</p>
      </div>
    </div>
  );
};

export default NativeCallback;
```

---

## Step 11: Create NotFound Page

File: `src/pages/NotFound.tsx`

```typescript
import { useLocation, Link } from 'react-router-dom';
import { Button } from '@/components/ui/button';

const NotFound = () => {
  const location = useLocation();

  return (
    <div className="flex min-h-screen items-center justify-center bg-background p-4">
      <div className="w-full max-w-sm space-y-6 text-center">
        <div>
          <h1 className="text-6xl font-bold text-muted-foreground">404</h1>
          <h2 className="mt-4 text-xl font-semibold">Page not found</h2>
          <p className="mt-2 text-sm text-muted-foreground">
            The page "{location.pathname}" doesn't exist.
          </p>
        </div>
        <Button asChild className="w-full">
          <Link to="/">Go to home</Link>
        </Button>
      </div>
    </div>
  );
};

export default NotFound;
```

---

## Step 12: Add Routes to App.tsx

File: `src/App.tsx`

```typescript
import { BrowserRouter, Routes, Route } from 'react-router-dom';
import Index from './pages/Index';
import Auth from './pages/Auth';
import NativeCallback from './pages/NativeCallback';
import NotFound from './pages/NotFound';
import SpaRedirector from './components/SpaRedirector';

function App() {
  return (
    <BrowserRouter>
      <SpaRedirector />
      <Routes>
        <Route path="/" element={<Index />} />
        <Route path="/auth" element={<Auth />} />
        <Route path="/native-callback" element={<NativeCallback />} />
        <Route path="*" element={<NotFound />} />
      </Routes>
    </BrowserRouter>
  );
}

export default App;
```

---

## Step 13: Create SPA Fallback Files

File: `src/components/SpaRedirector.tsx`

```typescript
import { useEffect } from "react";
import { useLocation, useNavigate } from "react-router-dom";

export default function SpaRedirector() {
  const location = useLocation();
  const navigate = useNavigate();

  useEffect(() => {
    const params = new URLSearchParams(location.search);
    const redirect = params.get("redirect");
    
    if (!redirect) return;

    try {
      const decoded = decodeURIComponent(redirect);
      // Preserve any hash or additional query params
      navigate(`${decoded}${location.hash ?? ""}`, { replace: true });
    } catch {
      console.error('Failed to decode redirect path');
    }
  }, [location.search, location.hash, navigate]);

  return null;
}
```

File: `public/404.html`

```html
<!doctype html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Redirecting</title>
  </head>
  <body>
    <script>
      (function () {
        // Preserve the full path including query params
        var redirect = window.location.pathname + window.location.search;
        var target = "/?redirect=" + encodeURIComponent(redirect);
        window.location.replace(target);
      })();
    </script>
  </body>
</html>
```

File: `public/_redirects`

```
/* /index.html 200
```

**Note on `_redirects`:** This file is for Netlify and Lovable hosting. If using a different hosting platform:
- **Vercel**: Create `vercel.json` with `{"rewrites": [{"source": "/(.*)", "destination": "/index.html"}]}`
- **Apache**: Use `.htaccess` with rewrite rules
- **Nginx**: Configure `try_files $uri /index.html`

---

## Step 14: Configuration Summary

**Before implementing, collect these from the user:**

1. TikTok Client Key (from TikTok Developer Portal)
2. TikTok Client Secret (from TikTok Developer Portal)
3. Lovable App URL (e.g., https://myapp.lovable.app)
4. Despia Deeplink Scheme (for native apps, e.g., myapp)

### Frontend (Hardcoded in src/lib/tiktok-auth.ts)

```typescript
export const TIKTOK_CLIENT_KEY = 'user_provided_key';      // FROM USER
export const APP_URL = 'https://user-app.lovable.app';     // FROM USER
```

### Backend (Supabase Edge Function Secrets)

Set these in Supabase Dashboard > Project Settings > Edge Functions > Secrets:

```
TIKTOK_CLIENT_KEY=user_provided_key
TIKTOK_CLIENT_SECRET=user_provided_secret
```

**Note**: The user must add these secrets manually. Lovable Cloud auto-provides `SUPABASE_URL`, `SUPABASE_ANON_KEY`, and `SUPABASE_SERVICE_ROLE_KEY`.

---

## Step 15: Using Login State in Your App

File: `src/pages/Index.tsx` (example)

```typescript
import { useEffect, useState } from 'react';
import { supabase } from '@/integrations/supabase/client';
import { User } from '@supabase/supabase-js';
import LoginButton from '@/components/LoginButton';
import { Button } from '@/components/ui/button';
import { Avatar, AvatarFallback, AvatarImage } from '@/components/ui/avatar';

const Index = () => {
  const [user, setUser] = useState<User | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    // Get initial session
    supabase.auth.getSession().then(({ data: { session } }) => {
      setUser(session?.user ?? null);
      setLoading(false);
    });

    // Listen for auth changes
    const { data: { subscription } } = supabase.auth.onAuthStateChange(
      (event, session) => {
        setUser(session?.user ?? null);
      }
    );

    return () => subscription.unsubscribe();
  }, []);

  const handleSignOut = async () => {
    await supabase.auth.signOut();
  };

  if (loading) {
    return (
      <div className="flex min-h-screen items-center justify-center">
        <div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" />
      </div>
    );
  }

  if (!user) {
    return (
      <div className="flex min-h-screen items-center justify-center p-4">
        <div className="w-full max-w-sm space-y-6 text-center">
          <h1 className="text-2xl font-bold">Welcome</h1>
          <p className="text-muted-foreground">Sign in with TikTok to continue</p>
          <LoginButton />
        </div>
      </div>
    );
  }

  // User is logged in
  const metadata = user.user_metadata;

  return (
    <div className="flex min-h-screen items-center justify-center p-4">
      <div className="w-full max-w-sm space-y-6 text-center">
        <Avatar className="mx-auto h-20 w-20">
          <AvatarImage src={metadata.avatar_url} alt={metadata.display_name} />
          <AvatarFallback>
            {metadata.display_name?.charAt(0) || 'U'}
          </AvatarFallback>
        </Avatar>
        
        <div>
          <h1 className="text-2xl font-bold">{metadata.display_name || 'TikTok User'}</h1>
          <p className="text-sm text-muted-foreground">
            TikTok ID: {metadata.tiktok_open_id}
          </p>
        </div>

        <Button onClick={handleSignOut} variant="outline" className="w-full">
          Sign Out
        </Button>
      </div>
    </div>
  );
};

export default Index;
```

---

## Configuration Checklist

### Credentials to Collect from User (REQUIRED FIRST)

- [ ] TikTok Client Key
- [ ] TikTok Client Secret
- [ ] Lovable App URL
- [ ] Despia Deeplink Scheme (for native apps)

### TikTok Developer Portal

- [ ] Created app with Login Kit enabled
- [ ] Added redirect URIs:
  - `https://{USER_APP_URL}/auth` (web)
  - `https://{USER_APP_URL}/native-callback` (native)
- [ ] Requested `user.info.basic` scope
- [ ] Noted Client Key and Client Secret

### Frontend Configuration (in src/lib/tiktok-auth.ts)

- [ ] Set `TIKTOK_CLIENT_KEY` to user's TikTok client key
- [ ] Set `APP_URL` to user's Lovable app URL

### Supabase

- [ ] Added edge function secrets (manually):
  - `TIKTOK_CLIENT_KEY`
  - `TIKTOK_CLIENT_SECRET`
- [ ] Verified auto-provided secrets exist:
  - `SUPABASE_URL` (auto)
  - `SUPABASE_ANON_KEY` (auto) - NOT "SUPABASE_PUBLISHABLE_KEY"
  - `SUPABASE_SERVICE_ROLE_KEY` (auto)
- [ ] Deployed `auth-tiktok-callback` edge function
- [ ] Set `verify_jwt = false` in config.toml

### Despia (for native apps)

- [ ] Set deeplink scheme in Despia Dashboard
- [ ] Updated `LoginButton.tsx` with user's scheme
- [ ] Updated `NativeCallback.tsx` with user's scheme

### App Code

- [ ] All files created and added to project
- [ ] Routes added to `App.tsx`

---

## Update Checklist

These values must be provided by the user before implementation:

| File | Placeholder | Replace With |
|------|-------------|--------------|
| src/lib/tiktok-auth.ts | `'USER_PROVIDED_CLIENT_KEY'` | User's TikTok client key |
| src/lib/tiktok-auth.ts | `'https://USER_PROVIDED_APP.lovable.app'` | User's Lovable app URL |
| LoginButton.tsx | `'myapp'` | User's Despia deeplink scheme |
| NativeCallback.tsx | `'myapp'` | User's Despia deeplink scheme |
| Supabase Secrets | - | `TIKTOK_CLIENT_KEY` and `TIKTOK_CLIENT_SECRET` |

---

## How It All Connects

```
WEB FLOW:
LoginButton -> getTikTokOAuthUrl() (frontend) -> TikTok OAuth Page
-> /auth?code=xxx -> auth-tiktok-callback (exchanges code + creates session)
-> setSession() -> Logged in

NATIVE FLOW:
LoginButton -> getTikTokOAuthUrl() (frontend) -> despia('oauth://?url=...')
-> ASWebAuthenticationSession opens -> TikTok OAuth
-> /native-callback?code=xxx -> auth-tiktok-callback (exchanges code + creates session)
-> myapp://oauth/auth?tokens (deeplink closes browser)
-> /auth?tokens -> setSession() -> Logged in
```

---

## Troubleshooting

| Problem | Solution |
|---------|----------|
| "supabaseKey is required" | Use `SUPABASE_ANON_KEY` not `` in edge function |
| "TikTok credentials not configured" | User has not provided their TikTok Client Key - ask them for it |
| "client_key" error from TikTok | The TIKTOK_CLIENT_KEY in tiktok-auth.ts is incorrect or placeholder |
| Invalid redirect URI | APP_URL in tiktok-auth.ts doesn't match TikTok Developer Portal settings |
| "bad_jwt" error | You're using manual JWT creation - use magic link + verifyOtp instead |
| Code exchange fails | Check TIKTOK_CLIENT_SECRET is correct in Supabase secrets |
| User can't log in | Make sure `email_confirm: true` when creating users |
| Session not persisting | Use `setSession()` on frontend, not just storing tokens |
| Native browser doesn't close | Use `myapp://oauth/...` format (oauth/ prefix required) |
| 401 on edge functions | Add `verify_jwt = false` to config.toml |
| verifyOtp type error | Try changing `type: 'email'` to `type: 'magiclink'` (version dependent) |
| Invalid OAuth state | State expired (>10 min) or sessionStorage unavailable (private browsing) |

---

## Security Considerations

1. **State Parameter**: The `validateOAuthState()` function validates the state parameter against stored values to prevent CSRF attacks. States expire after 10 minutes.
2. **Token Storage**: Tokens are stored temporarily in sessionStorage and cleaned up after use
3. **Server-side Exchange**: Authorization code exchange happens server-side, keeping client secret secure
4. **JWT Signing**: Uses Supabase's internal session generation for consistent, valid tokens
5. **Expiry**: OAuth states expire after 10 minutes, sessions follow Supabase defaults
6. **Private Browsing**: Gracefully handles sessionStorage unavailability in private browsing mode

---

## Files Summary

| File | Purpose |
|------|---------|
| supabase/functions/auth-tiktok-callback/index.ts | Single edge function - exchanges code, creates user, generates session |
| supabase/config.toml | Edge function configuration |
| src/lib/tiktok-auth.ts | Client-side auth helpers + shared APP_URL config |
| src/components/LoginButton.tsx | Unified login button |
| src/pages/Auth.tsx | Web OAuth callback + login page |
| src/pages/NativeCallback.tsx | Native OAuth callback |
| src/pages/NotFound.tsx | 404 error page |
| src/App.tsx | Route configuration |
| src/components/SpaRedirector.tsx | Handle 404 fallback |
| public/404.html | Preserve params on 404 |
| public/_redirects | SPA routing (Netlify/Lovable) |

For additional support or questions, please contact our support team at support@despia.com