fix: chat UI

internal/repository/chat_repo.go

@@ -1157,6 +1157,60 @@ func (r *ChatRepo) ReportMessage(ctx context.Context, reporterID, messageID, con
 	return nil
 }
 
+// PushCandidate is a participant plus the state that decides whether a new
+// message should reach them out-of-band.
+type PushCandidate struct {
+	UserID      string
+	MutedUntil  *time.Time
+	LastReadSeq int64
+}
+
+// PushCandidates lists everyone still in the thread except the sender.
+func (r *ChatRepo) PushCandidates(ctx context.Context, conversationID, senderID string) ([]PushCandidate, error) {
+	rows, err := r.pg.Pool.Query(ctx, `
+		SELECT user_id, muted_until, last_read_seq
+		FROM conversation_participants
+		WHERE conversation_id = $1 AND user_id <> $2 AND left_at IS NULL`,
+		conversationID, senderID)
+	if err != nil {
+		return nil, fmt.Errorf("push candidates: %w", err)
+	}
+	defer rows.Close()
+
+	out := []PushCandidate{}
+	for rows.Next() {
+		var c PushCandidate
+		if err := rows.Scan(&c.UserID, &c.MutedUntil, &c.LastReadSeq); err != nil {
+			return nil, fmt.Errorf("scan push candidate: %w", err)
+		}
+		out = append(out, c)
+	}
+	return out, rows.Err()
+}
+
+// UnreadConversations counts the caller's threads holding unread messages.
+//
+// Counts THREADS, not messages: the badge answers "is anything waiting for
+// me?", and one chatty group shouldn't dominate it.
+//
+// Muted threads are excluded. Unread still accrues on them and the inbox still
+// shows it — mute silences the alert, and a badge is an alert.
+func (r *ChatRepo) UnreadConversations(ctx context.Context, userID string) (int, error) {
+	var n int
+	err := r.pg.Pool.QueryRow(ctx, `
+		SELECT count(*)
+		FROM conversation_participants p
+		JOIN conversations c ON c.id = p.conversation_id
+		WHERE p.user_id = $1
+		  AND p.left_at IS NULL
+		  AND c.last_seq > p.last_read_seq
+		  AND (p.muted_until IS NULL OR p.muted_until <= now())`, userID).Scan(&n)
+	if err != nil {
+		return 0, fmt.Errorf("count unread conversations: %w", err)
+	}
+	return n, nil
+}
+
 // SetMute sets or clears the caller's mute on a thread. A nil until unmutes.
 //
 // Mute is per participant, not per conversation: muting a group silences it for