fix placeholder users being resolved by authentication flows

app/Auth/ActiveUserProvider.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Auth;
+
+use Illuminate\Auth\EloquentUserProvider;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+
+/**
+ * User provider that only resolves non-placeholder users.
+ *
+ * Placeholder users are created by imports and when members are removed from an
+ * organization. They can share an email address with a real user, so resolving a user by
+ * email can return a placeholder instead of the real account. The login flow filters them
+ * out explicitly, but the password broker and the guard credential checks (for example the
+ * password confirmation) resolve users through the configured user provider.
+ *
+ * Registered as the "eloquent" provider driver in the AuthServiceProvider, so it replaces the
+ * built-in one for every provider in config/auth.php.
+ */
+class ActiveUserProvider extends EloquentUserProvider
+{
+    /**
+     * @param  Model|null  $model
+     * @return Builder<Model>
+     */
+    #[\Override]
+    protected function newModelQuery($model = null): Builder
+    {
+        $query = parent::newModelQuery($model);
+        $query->getQuery()->where('is_placeholder', '=', false);
+
+        return $query;
+    }
+}

app/Models/User.php

@@ -38,7 +38,10 @@ use OwenIt\Auditing\Contracts\Auditable as AuditableContract;
  * @property string|null $pending_email
  * @property Carbon|null $email_verified_at
  * @property string|null $password
+ * @property string|null $remember_token
  * @property string|null $two_factor_secret
+ * @property string|null $two_factor_recovery_codes
+ * @property Carbon|null $two_factor_confirmed_at
  * @property string $timezone
  * @property bool $is_placeholder
  * @property Weekday $week_start
@@ -150,7 +153,9 @@ class User extends Authenticatable implements AuditableContract, FilamentUser, M
 
     public function canAccessPanel(Panel $panel): bool
     {
-        return in_array($this->email, config('auth.super_admins', []), true) && $this->hasVerifiedEmail();
+        return $this->is_placeholder === false
+            && in_array($this->email, config('auth.super_admins', []), true)
+            && $this->hasVerifiedEmail();
     }
 
     public function isMemberOfOrganization(Organization $organization): bool

app/Providers/AuthServiceProvider.php

@@ -4,11 +4,14 @@ declare(strict_types=1);
 
 namespace App\Providers;
 
+use App\Auth\ActiveUserProvider;
 use App\Models\Passport\AuthCode;
 use App\Models\Passport\Client;
 use App\Models\Passport\RefreshToken;
 use App\Models\Passport\Token;
+use Illuminate\Contracts\Foundation\Application;
 use Illuminate\Foundation\Support\Providers\AuthServiceProvider as ServiceProvider;
+use Illuminate\Support\Facades\Auth;
 use Laravel\Passport\Passport;
 
 class AuthServiceProvider extends ServiceProvider
@@ -26,6 +29,13 @@ class AuthServiceProvider extends ServiceProvider
      */
     public function boot(): void
     {
+        // Replaces the built-in eloquent user provider, so that no authentication flow can
+        // resolve a placeholder user. The driver name is kept, because Passport recognizes
+        // only providers that are configured with the driver "eloquent".
+        Auth::provider('eloquent', function (Application $app, array $config): ActiveUserProvider {
+            return new ActiveUserProvider($app->make('hash'), $config['model']);
+        });
+
         // define scopes for passport tokens
         Passport::tokensCan([
             'create' => 'Create resources',

app/Service/MemberService.php

@@ -218,7 +218,16 @@ class MemberService
 
         $placeholderUser = $user->replicate();
         $placeholderUser->is_placeholder = true;
-        $placeholderUser->current_team_id = $member->organization_id;
+        // Reset authentication relevant properties on the placeholder user
+        $placeholderUser->password = null;
+        $placeholderUser->remember_token = null;
+        $placeholderUser->two_factor_secret = null;
+        $placeholderUser->two_factor_recovery_codes = null;
+        $placeholderUser->two_factor_confirmed_at = null;
+        $placeholderUser->email_verified_at = null;
+        $placeholderUser->pending_email = null;
+        $placeholderUser->current_team_id = null;
+        $placeholderUser->profile_photo_path = null;
         $placeholderUser->save();
 
         $member->user()->associate($placeholderUser);