fix(bot): un-reacting from a poll never un-counted the vote

wyr/acronym/nhie/hottake tracked votes only on reaction-add, using
"add to bucket A, remove from bucket B" logic that self-corrects when
switching reactions but not when a reaction is simply removed — nio
never subscribed to RedactionEvent at all, so an un-react was
invisible to the bot. Fixes LotusGuild/matrix#6 (repro: react agree
and disagree, remove disagree, still counted as disagree).

Adds unrecord_* counterparts to each record_* vote function, a
reaction_id -> (poll_event_id, sender) index in Callbacks (only
populated for reactions on messages we're actually tracking, so it
stays bounded) so a later redaction can be traced back to what to
un-count, and wires up RedactionEvent -> callbacks.redaction in bot.py.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

matrixbot/bot.py

@@ -10,6 +10,7 @@ from nio import (
     InviteMemberEvent,
     LoginResponse,
     ReactionEvent,
+    RedactionEvent,
     RoomMemberEvent,
     RoomMessageText,
     UnknownEvent,
@@ -146,6 +147,7 @@ async def main():
     client.add_event_callback(callbacks.message, RoomMessageText)
     client.add_event_callback(callbacks.reaction, ReactionEvent)
     client.add_event_callback(callbacks.unknown_event, UnknownEvent)
+    client.add_event_callback(callbacks.redaction, RedactionEvent)
     client.add_event_callback(callbacks.member, RoomMemberEvent)
 
     # Accept invites only from trusted users, and decline the rest so they do

matrixbot/callbacks.py

@@ -13,6 +13,14 @@ from commands import (
     record_acronym_vote,
     record_nhie_reaction,
     record_hottake_reaction,
+    unrecord_wyr_vote,
+    unrecord_acronym_vote,
+    unrecord_nhie_reaction,
+    unrecord_hottake_reaction,
+    _WYR_POLLS,
+    _ACRONYM_POLL_IDS,
+    _NHIE_POLLS,
+    _HOTTAKE_POLLS,
 )
 logger = logging.getLogger("matrixbot")
 
@@ -33,11 +41,25 @@ def handle_command_errors(func):
     return wrapper
 
 
+def _is_tracked_poll(event_id: str) -> bool:
+    return (
+        event_id in _WYR_POLLS
+        or event_id in _ACRONYM_POLL_IDS
+        or event_id in _NHIE_POLLS
+        or event_id in _HOTTAKE_POLLS
+    )
+
+
 class Callbacks:
     def __init__(self, client: AsyncClient):
         self.client = client
         # Track the sync token so we ignore old messages on startup
         self.startup_sync_token = None
+        # reaction event_id -> (poll message event_id, sender), so an
+        # un-react (m.room.redaction of the reaction) can be traced back to
+        # which poll/sender to remove — only populated for reactions on a
+        # message we're actually tracking, so it stays bounded.
+        self._reaction_index: dict[str, tuple[str, str]] = {}
 
     async def message(self, room, event):
         # Ignore messages from before the bot started
@@ -97,6 +119,8 @@ class Callbacks:
         record_acronym_vote(reacted_event_id, event.sender, key)
         record_nhie_reaction(reacted_event_id, event.sender, key)
         record_hottake_reaction(reacted_event_id, event.sender, key)
+        if _is_tracked_poll(reacted_event_id):
+            self._reaction_index[event.event_id] = (reacted_event_id, event.sender)
 
     async def unknown_event(self, room, event):
         """Fallback handler for UnknownEvent — catches any m.reaction not parsed by nio."""
@@ -120,6 +144,28 @@ class Callbacks:
         record_acronym_vote(reacted_event_id, event.sender, key)
         record_nhie_reaction(reacted_event_id, event.sender, key)
         record_hottake_reaction(reacted_event_id, event.sender, key)
+        if _is_tracked_poll(reacted_event_id):
+            self._reaction_index[event.event_id] = (reacted_event_id, event.sender)
+
+    async def redaction(self, room, event):
+        """Handle m.room.redaction — an un-react. Reaction adds are tracked
+        via `reaction`/`unknown_event` above; this is their counterpart so a
+        removed vote doesn't stay counted forever (it previously only
+        self-corrected when a user switched to a different reaction, not
+        when they simply removed one — see LotusGuild/matrix#6)."""
+        if self.startup_sync_token is None:
+            return
+
+        entry = self._reaction_index.pop(event.redacts, None)
+        if entry is None:
+            return
+        reacted_event_id, sender = entry
+        logger.info("reaction removed: target=%s sender=%s", reacted_event_id[:16], sender)
+
+        unrecord_wyr_vote(reacted_event_id, sender)
+        unrecord_acronym_vote(reacted_event_id, sender)
+        unrecord_nhie_reaction(reacted_event_id, sender)
+        unrecord_hottake_reaction(reacted_event_id, sender)
 
     async def member(self, room, event):
         """Handle m.room.member events.

matrixbot/commands.py

@@ -1842,6 +1842,15 @@ def record_wyr_vote(event_id: str, sender: str, key: str) -> None:
         poll["votes"][key].add(sender)
 
 
+def unrecord_wyr_vote(event_id: str, sender: str) -> None:
+    """Called from callbacks when a reaction is removed from a WYR poll message."""
+    poll = _WYR_POLLS.get(event_id)
+    if not poll:
+        return
+    for bucket in poll["votes"].values():
+        bucket.discard(sender)
+
+
 async def _generate_wyr() -> dict | None:
     # Few-shot examples anchor the format so the model doesn't drift
     examples = [
@@ -2680,6 +2689,17 @@ def record_acronym_vote(event_id: str, sender: str, key: str) -> None:
         game.setdefault("votes", {})[sender] = idx  # one vote per person
 
 
+def unrecord_acronym_vote(event_id: str, sender: str) -> None:
+    """Record a numbered-emoji vote removal on an acronym poll."""
+    room_id = _ACRONYM_POLL_IDS.get(event_id)
+    if room_id is None:
+        return
+    game = _ACRONYM_GAMES.get(room_id)
+    if not game or game.get("phase") != "voting":
+        return
+    game.get("votes", {}).pop(sender, None)
+
+
 @command("acronym", "AI picks an acronym — submit the funniest expansion with !ac, then vote!")
 async def cmd_acronym(client: AsyncClient, room_id: str, sender: str, args: str):
     if room_id in _ACRONYM_GAMES:
@@ -3036,6 +3056,14 @@ def record_nhie_reaction(event_id: str, sender: str, key: str) -> None:
         poll["have"].discard(sender)
 
 
+def unrecord_nhie_reaction(event_id: str, sender: str) -> None:
+    poll = _NHIE_POLLS.get(event_id)
+    if not poll:
+        return
+    poll["have"].discard(sender)
+    poll["never"].discard(sender)
+
+
 _NHIE_TOPICS = [
     "travel", "food", "social situations", "school or work", "technology",
     "outdoor adventures", "relationships", "embarrassing moments",
@@ -3138,6 +3166,14 @@ def record_hottake_reaction(event_id: str, sender: str, key: str) -> None:
         poll["agree"].discard(sender)
 
 
+def unrecord_hottake_reaction(event_id: str, sender: str) -> None:
+    poll = _HOTTAKE_POLLS.get(event_id)
+    if not poll:
+        return
+    poll["agree"].discard(sender)
+    poll["disagree"].discard(sender)
+
+
 _HOTTAKE_TOPICS = [
     "food and cooking", "music genres", "social media and technology",
     "sports and fitness", "video games", "movies and TV shows",