Fix typecheck errors in prefix disambiguation

src/mudlib/commands/__init__.py

@@ -3,6 +3,7 @@
 import logging
 from collections.abc import Awaitable, Callable
 from dataclasses import dataclass, field
+from typing import cast
 
 from mudlib.player import Player
 
@@ -130,7 +131,8 @@ async def dispatch(player: Player, raw_input: str) -> None:
         if len(names) == 2:
             msg = f"{names[0]} or {names[1]}?\r\n"
         else:
-            msg = f"{', '.join(names[:-1])}, or {names[-1]}?\r\n"
+            prefix = ", ".join(cast(list[str], names[:-1]))
+            msg = f"{prefix}, or {names[-1]}?\r\n"
         player.writer.write(msg)
         await player.writer.drain()
         return

src/mudlib/commands/help.py

@@ -1,6 +1,6 @@
 """Help and command listing commands."""
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 
 from mudlib.commands import CommandDefinition, _registry, register, resolve_prefix
 from mudlib.commands.movement import DIRECTIONS
@@ -28,7 +28,8 @@ async def _show_command_detail(player: Player, command_name: str) -> None:
         if len(names) == 2:
             msg = f"{names[0]} or {names[1]}?\r\n"
         else:
-            msg = f"{', '.join(names[:-1])}, or {names[-1]}?\r\n"
+            prefix = ", ".join(cast(list[str], names[:-1]))
+            msg = f"{prefix}, or {names[-1]}?\r\n"
         await player.send(msg)
         return
     else: