docs: align queue workload defaults with production topology

config/queue.php

@@ -20,16 +20,21 @@ return [
     | Workload Queue Names
     |--------------------------------------------------------------------------
     |
-    | Defaults match the current multi-server production topology: only the PDF
-    | worker fleet consumes "pdf" at scale, while the main server has one
-    | default worker. Move analysis to another queue only after deploying
-    | workers for that queue on the PDF/worker nodes.
+    | Production currently has only two consumed queues:
+    | - default: one worker on the main server for non-PDF background work.
+    | - pdf: nine workers across main/pdf-1/pdf-2 for PDFs and heavy analysis.
+    |
+    | Keep report-critical work on "pdf"; move only non-critical follow-up work
+    | away from the PDF worker fleet.
     |
     */
 
     'workloads' => [
         'pdf' => env('QUEUE_PDF', 'pdf'),
+        // Keep answer analysis on the scaled pdf worker fleet. Do not point
+        // this at default unless default workers are scaled out.
         'exam_answer_analysis' => env('QUEUE_EXAM_ANSWER_ANALYSIS', 'pdf'),
+        // This follow-up is not on the visible report-generation path.
         'question_difficulty_calibration' => env('QUEUE_QUESTION_DIFFICULTY_CALIBRATION', 'default'),
         'question_difficulty_calibration_delay_seconds' => (int) env('QUEUE_QUESTION_DIFFICULTY_CALIBRATION_DELAY_SECONDS', 30),
     ],