Fix vote count hot score calculation inconsistency

packages/backend/src/graphql/resolvers/social/notifications.ts

@@ -154,7 +154,7 @@ export const socialNotificationQueries = {
           MAX(n."created_at") as "latestCreatedAt",
           BOOL_AND(n."read_at" IS NOT NULL) as "allRead",
           (array_agg(c."body" ORDER BY n."created_at" DESC))[1] as "commentBody",
-          (array_agg(DISTINCT n."actor_id"))[1:3] as "actorIds"
+          (array_remove(array_agg(DISTINCT n."actor_id"), NULL))[1:3] as "actorIds"
         FROM "notifications" n
         LEFT JOIN "comments" c ON n."comment_id" = c."id"
         WHERE n."recipient_id" = ${userId}
@@ -197,12 +197,14 @@ export const socialNotificationQueries = {
       const actorAvatarUrls = row.actorAvatarUrls || [];
 
       const actors = actorIds
-        .filter((id): id is string => id != null)
         .map((id, i) => ({
           id,
           displayName: actorDisplayNames[i] || undefined,
           avatarUrl: actorAvatarUrls[i] || undefined,
-        }));
+        }))
+        .filter((actor): actor is { id: string; displayName: string | undefined; avatarUrl: string | undefined } =>
+          actor.id != null,
+        );
 
       return {
         uuid: row.latestUuid,

packages/db/drizzle/0056_fix_vote_counts_hot_score_fallback.sql

@@ -0,0 +1,76 @@
+-- Fix update_vote_counts trigger to use MIN(votes.created_at) as fallback
+-- instead of NOW() when no feed_items row exists.
+--
+-- Previously the trigger used NOW() as the fallback, while the backfill in
+-- 0053_add_vote_counts.sql used MIN(v.created_at). This caused inconsistent
+-- hot_score calculations: when a previously-backfilled entity received a new
+-- vote, the trigger would recalculate using NOW() instead of the original
+-- earliest vote time, artificially boosting the entity's hot_score.
+
+CREATE OR REPLACE FUNCTION update_vote_counts() RETURNS trigger AS $$
+DECLARE
+  v_entity_type social_entity_type;
+  v_entity_id text;
+  v_up int;
+  v_down int;
+  v_score int;
+  v_hot_score double precision;
+  v_created_at timestamp;
+BEGIN
+  -- Determine which entity was affected
+  IF TG_OP = 'DELETE' THEN
+    v_entity_type := OLD.entity_type;
+    v_entity_id := OLD.entity_id;
+  ELSE
+    v_entity_type := NEW.entity_type;
+    v_entity_id := NEW.entity_id;
+  END IF;
+
+  -- Recount (safe, idempotent)
+  SELECT
+    COALESCE(SUM(CASE WHEN value = 1 THEN 1 ELSE 0 END), 0),
+    COALESCE(SUM(CASE WHEN value = -1 THEN 1 ELSE 0 END), 0)
+  INTO v_up, v_down
+  FROM votes
+  WHERE entity_type = v_entity_type AND entity_id = v_entity_id;
+
+  v_score := v_up - v_down;
+
+  -- Get entity creation time from feed_items if available, otherwise fall back
+  -- to the earliest vote time. Using MIN(created_at) from votes is consistent
+  -- with the backfill logic and provides a stable proxy for entity age.
+  SELECT COALESCE(
+    (SELECT fi."created_at" FROM feed_items fi
+     WHERE fi."entity_type" = v_entity_type::text AND fi."entity_id" = v_entity_id
+     LIMIT 1),
+    (SELECT MIN(vt."created_at") FROM votes vt
+     WHERE vt."entity_type" = v_entity_type AND vt."entity_id" = v_entity_id)
+  ) INTO v_created_at;
+
+  -- Final fallback to NOW() only if no votes exist (shouldn't happen in
+  -- practice since this trigger fires on the votes table)
+  IF v_created_at IS NULL THEN
+    v_created_at := NOW();
+  END IF;
+
+  -- Hot score: sign(score) * ln(max(|score|, 1)) + epoch/45000
+  v_hot_score := SIGN(v_score) * LN(GREATEST(ABS(v_score), 1))
+    + EXTRACT(EPOCH FROM v_created_at) / 45000.0;
+
+  -- Upsert
+  INSERT INTO vote_counts (entity_type, entity_id, upvotes, downvotes, score, hot_score, created_at)
+  VALUES (v_entity_type, v_entity_id, v_up, v_down, v_score, v_hot_score, v_created_at)
+  ON CONFLICT (entity_type, entity_id) DO UPDATE SET
+    upvotes = EXCLUDED.upvotes,
+    downvotes = EXCLUDED.downvotes,
+    score = EXCLUDED.score,
+    hot_score = EXCLUDED.hot_score;
+
+  -- Clean up zero-vote rows
+  IF v_up = 0 AND v_down = 0 THEN
+    DELETE FROM vote_counts WHERE entity_type = v_entity_type AND entity_id = v_entity_id;
+  END IF;
+
+  RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;