# Check Node.js version
node --version  # Should be 18+

# Check npm version
npm --version   # Should be 9+

# Verify dependencies installed
ls node_modules | wc -l  # Should be 200+

# Check environment variables
cat .env | grep SUPABASE

# Test build
npm run build

# Check for TypeScript errors
npm run typecheck

# Clear npm cache
npm cache clean --force

# Delete existing modules and lockfile
rm -rf node_modules package-lock.json

# Reinstall
npm install

# If still failing, try with legacy peer deps
npm install --legacy-peer-deps

# Increase Node memory
export NODE_OPTIONS="--max-old-space-size=4096"
npm install

# Check current version
node --version

# Switch to correct version with nvm
nvm install 20
nvm use 20

# Or use .nvmrc
echo "20" > .nvmrc
nvm use

# Fix npm permissions (don't use sudo!)
mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.bashrc
source ~/.bashrc

# Or use nvm (recommended)
nvm install 20

# 1. Verify .env file exists
ls -la .env

# 2. Check file format (no quotes around values)
cat .env

# 3. Correct format:
NEXT_PUBLIC_SUPABASE_URL=https://xxx.supabase.co
NEXT_PUBLIC_SUPABASE_ANON_KEY=eyJ...

# Wrong format:
NEXT_PUBLIC_SUPABASE_URL="https://xxx.supabase.co"  # No quotes!

# Kill existing server (Ctrl+C) then:
npm run dev

# Correct (available in browser)
NEXT_PUBLIC_SUPABASE_URL=https://xxx.supabase.co

# Wrong (only available server-side)
SUPABASE_URL=https://xxx.supabase.co

# 1. Verify URL and key
echo $NEXT_PUBLIC_SUPABASE_URL
echo $NEXT_PUBLIC_SUPABASE_ANON_KEY

# 2. Test connection
curl https://your-project.supabase.co/rest/v1/ \
  -H "apikey: your-anon-key"

# 3. Check project status in Supabase dashboard
# Projects pause after 1 week of inactivity (free tier)

-- Check RLS is enabled
SELECT tablename, rowsecurity
FROM pg_tables
WHERE schemaname = 'public';

-- Check policies exist
SELECT tablename, policyname
FROM pg_policies
WHERE schemaname = 'public';

-- Verify user is authenticated
-- In your code:
const { data: { user } } = await supabase.auth.getUser();
console.log('User:', user);  // Should not be null

-- Check if user matches policy
-- For "users can view own agents":
SELECT * FROM agents WHERE user_id = 'your-user-id';

# Check migration status
supabase migration list

# Re-run failed migration manually in SQL Editor
# Copy SQL from supabase/migrations/xxx.sql

# Repair migration status
supabase migration repair --status applied 20260107174235

// Debug auth state
const { data, error } = await supabase.auth.signInWithPassword({
  email: 'test@example.com',
  password: 'password'
});

console.log('Auth result:', { data, error });

// Ensure auth state listener is set up
useEffect(() => {
  const { data: { subscription } } = supabase.auth.onAuthStateChange(
    (event, session) => {
      console.log('Auth event:', event, session);
    }
  );

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

UPDATE auth.users
SET email_confirmed_at = NOW()
WHERE email = 'test@example.com';

# Find all TypeScript errors
npm run typecheck

# Common fixes:

# 1. Missing types - add type annotations
const data: Agent[] = response.data;

# 2. Null checks
const name = agent?.name ?? 'Unknown';

# 3. Type assertions (use sparingly)
const data = response as AgentResponse;

# 1. Check import path
# Correct: import { Button } from '@/components/ui/button';
# Wrong:   import { Button } from 'components/ui/button';

# 2. Verify tsconfig paths
cat tsconfig.json | grep paths

# 3. Restart TypeScript server in VS Code
# Cmd+Shift+P > "TypeScript: Restart TS Server"

# Increase Node memory for build
NODE_OPTIONS="--max-old-space-size=4096" npm run build

# Or in package.json:
"scripts": {
  "build": "NODE_OPTIONS='--max-old-space-size=4096' next build"
}

// 1. Use useEffect for client-only code
const [mounted, setMounted] = useState(false);

useEffect(() => {
  setMounted(true);
}, []);

if (!mounted) return null;

// 2. Suppress hydration warning (last resort)
<div suppressHydrationWarning>{clientOnlyContent}</div>

// 1. Verify subscription is active
const channel = supabase
  .channel('test')
  .on('postgres_changes', { event: '*', schema: 'public', table: 'messages' },
    (payload) => console.log('Change:', payload)
  )
  .subscribe((status) => {
    console.log('Subscription status:', status);
  });

// 2. Check Replication settings in Supabase
// Database > Replication > Enable for table

// 3. Ensure table has RLS allowing select

// Implement retry with backoff
async function fetchWithRetry(url: string, options: RequestInit, retries = 3) {
  for (let i = 0; i < retries; i++) {
    const response = await fetch(url, options);

    if (response.status === 429) {
      const retryAfter = response.headers.get('Retry-After') || '60';
      await new Promise(r => setTimeout(r, parseInt(retryAfter) * 1000));
      continue;
    }

    return response;
  }
  throw new Error('Max retries exceeded');
}

# View function logs
supabase functions logs function-name --follow

# Common causes:
# 1. Missing environment variable
# 2. Invalid JSON parsing
# 3. Unhandled exception

const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Methods": "GET, POST, PUT, DELETE, OPTIONS",
  "Access-Control-Allow-Headers": "Content-Type, Authorization, X-Client-Info, Apikey",
};

// Handle OPTIONS preflight
if (req.method === "OPTIONS") {
  return new Response(null, { status: 200, headers: corsHeaders });
}

// Include in ALL responses
return new Response(data, {
  headers: { ...corsHeaders, "Content-Type": "application/json" }
});

// 1. Optimize slow operations
// 2. Use streaming for long responses
// 3. Break into smaller functions
// 4. Use background tasks for heavy work

// 1. Use dynamic imports
const HeavyComponent = dynamic(() => import('./HeavyComponent'), {
  loading: () => <Skeleton />
});

// 2. Optimize images
<Image src={url} width={400} height={300} loading="lazy" />

// 3. Reduce bundle size
npm run build
# Check output sizes

// Clean up subscriptions
useEffect(() => {
  const channel = supabase.channel('test').subscribe();

  return () => {
    supabase.removeChannel(channel);  // Cleanup!
  };
}, []);

// Clean up timers
useEffect(() => {
  const timer = setInterval(callback, 1000);
  return () => clearInterval(timer);  // Cleanup!
}, []);

# Full system diagnostics
npm run typecheck && npm run lint && npm run build

# Reset everything
rm -rf node_modules .next package-lock.json
npm install
npm run dev