8ball: add --debug flag to show post-processed prompt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

matrixbot/commands.py

@@ -218,6 +218,10 @@ async def cmd_8ball(client: AsyncClient, room_id: str, sender: str, args: str):
         await send_text(client, room_id, f"Usage: {BOT_PREFIX}8ball <question>")
         return
 
+    debug = args.rstrip().endswith("--debug")
+    if debug:
+        args = args.rstrip()[:-len("--debug")].rstrip()
+
     WYNTER_ID = "@wynter:mozilla.org"
     JARED_ID = "@jared:matrix.lotusguild.org"
 
@@ -377,6 +381,7 @@ async def cmd_8ball(client: AsyncClient, room_id: str, sender: str, args: str):
             f'<font color="{_answer_color}"><strong>🎱 {answer}</strong></font><br>'
             f'<sup><em>{args}</em></sup>'
             + (f'<br><sup><em>via {_model_label(BALL_MODEL)}</em></sup>' if used_llm else "")
+            + (f'<br><sup><em>[debug] prompt: {q_for_prompt}</em></sup>' if debug else "")
         )
         await send_html(client, room_id, plain, html)
         return