++ fix: use months for assignment PDF link TTL instead of hours

app/Models/Assegnazione.php

@@ -4,6 +4,8 @@ namespace App\Models;
 
 use Carbon\Carbon;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Support\Facades\URL;
+use Illuminate\Support\Str;
 
 class Assegnazione extends Model
 {
@@ -17,6 +19,7 @@ class Assegnazione extends Model
         'returned_at',
         'counted_in_campaign',
         'campaign_id',
+        'pdf_access_code',
         'note',
         'created_by',
         'returned_by',
@@ -79,6 +82,39 @@ class Assegnazione extends Model
         return is_null($this->returned_at);
     }
 
+    public function ensurePdfAccessCode(): string
+    {
+        if ($this->pdf_access_code) {
+            return $this->pdf_access_code;
+        }
+
+        do {
+            $code = strtoupper(Str::random(12));
+        } while (static::query()->where('pdf_access_code', $code)->exists());
+
+        $this->forceFill(['pdf_access_code' => $code])->saveQuietly();
+
+        return $code;
+    }
+
+    public function temporaryPdfViewerUrl(): ?string
+    {
+        if (! $this->is_aperta || ! $this->territorio?->pdf_path) {
+            return null;
+        }
+
+        $months = max(1, (int) Setting::getValue('assignment_link_ttl_hours', 1));
+
+        return URL::temporarySignedRoute(
+            'assignments.pdf.viewer',
+            now()->addMonths($months),
+            [
+                'assignment' => $this->id,
+                'code' => $this->ensurePdfAccessCode(),
+            ]
+        );
+    }
+
     // ─── Scopes ─────────────────────────────────────────────────
 
     public function scopeAperte($query)