feat: Treat pairing-DM replies as activity

pairing_bot.go

@@ -75,6 +75,20 @@ func (pl *PairingLogic) handle(w http.ResponseWriter, r *http.Request) {
 	// distinguish these by checking whether there are exactly two participants
 	// (Pairing Bot + 1).
 	if len(hook.Message.DisplayRecipient.Users) != 2 {
+		// But still reset the open pairings count for anyone trying to
+		// schedule something!
+		rec, err := pl.rdb.GetByUserID(ctx, hook.Message.SenderID, hook.Message.SenderEmail, hook.Message.SenderFullName)
+		if err != nil {
+			log.Println(err)
+		}
+
+		if rec.isSubscribed {
+			rec.openPairings = 0
+			if err := pl.rdb.Set(ctx, rec.id, rec); err != nil {
+				log.Printf("Could not reset openPairings count for user (%d): %s", rec.id, err)
+			}
+		}
+
 		if err := responder.Encode(zulip.NoResponse()); err != nil {
 			log.Println(err)
 		}