Patch d.py's message convertor to infer channelID from the given context

bot/__init__.py

@@ -18,6 +18,11 @@
 
 monkey_patches.patch_typing()
 
+# This patches any convertors that use PartialMessage, but not the PartialMessageConverter itself
+# as library objects are made by this mapping.
+# https://github.com/Rapptz/discord.py/blob/1a4e73d59932cdbe7bf2c281f25e32529fc7ae1f/discord/ext/commands/converter.py#L984-L1004
+commands.converter.PartialMessageConverter = monkey_patches.FixedPartialMessageConverter
+
 # Monkey-patch discord.py decorators to use the Command subclass which supports root aliases.
 # Must be patched before any cogs are added.
 commands.command = partial(commands.command, cls=monkey_patches.Command)

bot/monkey_patches.py

@@ -5,6 +5,7 @@
 from discord.ext import commands
 
 from bot.log import get_logger
+from bot.utils.regex import MESSAGE_ID_RE
 
 log = get_logger(__name__)
 
@@ -50,3 +51,25 @@ async def honeybadger_type(self, channel_id: int) -> None:  # noqa: ANN001
             pass
 
     http.HTTPClient.send_typing = honeybadger_type
+
+
+class FixedPartialMessageConverter(commands.PartialMessageConverter):
+    """
+    Make the Message converter infer channelID from the given context if only a messageID is given.
+
+    Discord.py's Message converter is supposed to infer channelID based
+    on ctx.channel if only a messageID is given. A refactor commit, linked below,
+    a few weeks before d.py's archival broke this defined behaviour of the converter.
+    Currently, if only a messageID is given to the converter, it will only find that message
+    if it's in the bot's cache.
+
+    https://github.com/Rapptz/discord.py/commit/1a4e73d59932cdbe7bf2c281f25e32529fc7ae1f
+    """
+
+    @staticmethod
+    def _get_id_matches(ctx: commands.Context, argument: str) -> tuple[int, int, int]:
+        """Inserts ctx.channel.id before calling super method if argument is just a messageID."""
+        match = MESSAGE_ID_RE.match(argument)
+        if match:
+            argument = f"{ctx.channel.id}-{match.group('message_id')}"
+        return commands.PartialMessageConverter._get_id_matches(ctx, argument)

bot/utils/regex.py

@@ -12,3 +12,4 @@
     r"(?P<invite>[a-zA-Z0-9\-]+)",                # the invite code itself
     flags=re.IGNORECASE
 )
+MESSAGE_ID_RE = re.compile(r'(?P<message_id>[0-9]{15,20})$')