fix: resolve Magic Link auth error from duplicate profile creation race condition

[Copilot]

On first Magic Link sign-in, users see "Failed to create profile: duplicate key value violates unique constraint 'users_pkey'" in the redirect tab, despite the session being valid in the original tab.

Root Cause

Two async flows call loadUserProfile() concurrently on page load:

• initializeAuth() → restoreSession() → loadUserProfile()
• onAuthStateChange(SIGNED_IN) → loadUserProfile()

The profileLoadingRef guard can be bypassed when both calls enter before either sets the flag. Both find no profile (PGRST116), both attempt INSERT, second one hits users_pkey unique violation.

Fix

When INSERT fails with Postgres error 23505, treat it as a race — fetch and load the already-created profile instead of surfacing an error.

if (createError.code === POSTGRES_UNIQUE_VIOLATION) {
  const { data: existingProfile } = await supabase
    .from('users').select('*').eq('id', user.id).single()
  // load existingProfile normally...
}

Also extracted POSTGRES_UNIQUE_VIOLATION = '23505' as a named constant.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
illinihunt	Ready	Preview, Comment	Apr 14, 2026 11:59pm