fix: push realtime del presence to topic sessions on message recall

The REST recall response reached only the caller, so peers kept showing the
recalled message until a full resync. broadcastIMMessageRecalled now pushes
the native {pres what:del delseq} tombstone through the hub for both single
and batch recall (empty pres topic for p2p, required by handlePresence's
xoriginal check); clients flush the message and render the recalled
placeholder. Zentao #16, #2.

server/im_http.go

@@ -3161,6 +3161,50 @@ func serveIMMessageReceipts(wrt http.ResponseWriter, req *http.Request) {
 	})
 }
 
+// broadcastIMMessageRecalled pushes the native {pres what:"del" delseq} frame to
+// the sessions currently attached to the topic so peers learn about a recall in
+// real time (the REST response alone reaches only the caller). The wire record
+// carries "low" only (no "hi"): client SDKs then flush the message from their
+// local cache and leave a content-less tombstone behind, which the webapp
+// renders as the usual "recalled" placeholder. Routed through the hub so the
+// p2p topic rewrites the frame's topic name to each recipient's own view.
+func broadcastIMMessageRecalled(tenantID types.TenantID, topic string, seqs []int64, actor types.Uid) {
+	if globals.hub == nil || topic == "" || actor.IsZero() {
+		return
+	}
+	delseq := make([]MsgRange, 0, len(seqs))
+	for _, seq := range seqs {
+		if seq > 0 {
+			delseq = append(delseq, MsgRange{LowId: seq})
+		}
+	}
+	if len(delseq) == 0 {
+		return
+	}
+	// P2P topics are loaded under their canonical name with xoriginal cleared,
+	// so the presence frame must carry an empty topic name to pass the
+	// handlePresence xoriginal check; any other category uses the topic name.
+	presTopic := topic
+	if types.GetTopicCat(topic) == types.TopicCatP2P {
+		presTopic = ""
+	}
+	select {
+	case globals.hub.routeSrv <- &ServerComMessage{
+		TenantID: tenantID,
+		RcptTo:   topic,
+		Pres: &MsgServerPres{
+			Topic:    presTopic,
+			What:     "del",
+			Src:      actor.UserId(),
+			DelSeq:   delseq,
+			FilterIn: int(types.ModeRead),
+		},
+	}:
+	default:
+		logs.Warn.Printf("im message recall: hub presence queue full topic=%s count=%d", topic, len(delseq))
+	}
+}
+
 func serveIMMessageRecall(wrt http.ResponseWriter, req *http.Request) {
 	if req.Method != http.MethodPost {
 		writeIMError(wrt, req, http.StatusMethodNotAllowed, 30002, imReasonMethodNotAllowed, "method not allowed", nil)
@@ -3215,6 +3259,7 @@ func serveIMMessageRecall(wrt http.ResponseWriter, req *http.Request) {
 			return
 		}
 	}
+	broadcastIMMessageRecalled(principal.TenantID, updated.Topic, []int64{seq}, principal.Uid)
 	writeIMSuccess(wrt, req, messageMutationPayload(updated, "recalled"))
 }
 
@@ -3242,6 +3287,7 @@ func serveIMMessageBatchRecall(wrt http.ResponseWriter, req *http.Request) {
 		return
 	}
 	items := make([]map[string]any, 0, len(body.Items))
+	recalledSeqs := make([]int64, 0, len(body.Items))
 	recalledAt := time.Now().UTC().Round(time.Millisecond)
 	for _, item := range body.Items {
 		if item.Seq <= 0 {
@@ -3281,7 +3327,9 @@ func serveIMMessageBatchRecall(wrt http.ResponseWriter, req *http.Request) {
 			}
 		}
 		items = append(items, result)
+		recalledSeqs = append(recalledSeqs, item.Seq)
 	}
+	broadcastIMMessageRecalled(principal.TenantID, topic, recalledSeqs, principal.Uid)
 	writeIMSuccess(wrt, req, map[string]any{"topic": topic, "items": items})
 }