diff --git a/internal/server/e2e_test.go b/internal/server/e2e_test.go
index 048d6d6..0104371 100644
--- a/internal/server/e2e_test.go
+++ b/internal/server/e2e_test.go
@@ -371,6 +371,57 @@ func TestHITLChoiceFlow(t *testing.T) {
 	}
 }
 
+func TestConversationResumeSeq(t *testing.T) {
+	srv, st := newTestServer(t)
+	h := srv.Handler()
+	_, convID := setupConversation(t, h)
+	runID := postMessage(t, h, convID, "#hitl")
+
+	deadline := time.Now().Add(5 * time.Second)
+	var waiting map[string]any
+	for time.Now().Before(deadline) && waiting == nil {
+		code, d := doJSON(t, h, "GET", "/api/conversations/"+convID, nil)
+		if code == 200 {
+			if cards, ok := d["activeHitl"].([]any); ok && len(cards) > 0 {
+				waiting = d
+			}
+		}
+		time.Sleep(30 * time.Millisecond)
+	}
+	if waiting == nil {
+		t.Fatal("no active hitl card")
+	}
+	lastSeq := int64(waiting["lastSeq"].(float64))
+	resumeSeq := int64(waiting["resumeSeq"].(float64))
+	var first int64
+	for _, e := range replayEvents(t, st, convID) {
+		if string(e.RunID) == runID {
+			first = e.Seq
+			break
+		}
+	}
+	if first == 0 {
+		t.Fatal("run has no events")
+	}
+	if resumeSeq != first-1 {
+		t.Fatalf("resumeSeq = %d, want first-1 = %d", resumeSeq, first-1)
+	}
+	if resumeSeq >= lastSeq {
+		t.Fatalf("resumeSeq %d should be before lastSeq %d while the run is open", resumeSeq, lastSeq)
+	}
+
+	cardID := waiting["activeHitl"].([]any)[0].(map[string]any)["id"].(string)
+	mustCode(t, h, "POST", "/api/hitl/"+cardID+"/resolve", map[string]any{"choiceId": "md"})
+	terminal := waitRunTerminal(t, h, runID, 5*time.Second)
+	if terminal["status"] != "completed" {
+		t.Fatalf("run status after resolve: %v", terminal["status"])
+	}
+	_, settled := doJSON(t, h, "GET", "/api/conversations/"+convID, nil)
+	if int64(settled["resumeSeq"].(float64)) != int64(settled["lastSeq"].(float64)) {
+		t.Fatalf("resumeSeq = %v, lastSeq = %v, want them equal after the run ends", settled["resumeSeq"], settled["lastSeq"])
+	}
+}
+
 func TestHITLFreeTextPivot(t *testing.T) {
 	srv, _ := newTestServer(t)
 	h := srv.Handler()
diff --git a/internal/server/server.go b/internal/server/server.go
index 1164c01..c7b965a 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -492,9 +492,16 @@ func (s *Server) conversationDetail(w http.ResponseWriter, r *http.Request) {
 	runs, _ := s.st.ListRunsByConversation(id)
 	cards, _ := s.st.ActiveHITLCards(owner, id)
 	lastSeq, _ := s.st.LastEventSeq(id)
+	// resumeSeq：进行中的 run 从它的第一条事件之前重放，刷新或切回时补回已产生的过程。
+	resumeSeq := lastSeq
+	if open, err := s.st.LatestOpenRun(id); err == nil {
+		if seq, ok, ferr := s.st.FirstRunEventSeq(id, open.ID); ferr == nil && ok && seq > 0 {
+			resumeSeq = seq - 1
+		}
+	}
 	writeJSON(w, http.StatusOK, map[string]any{
 		"conversation": conv, "messages": msgs, "runs": runs,
-		"activeHitl": cards, "lastSeq": lastSeq,
+		"activeHitl": cards, "lastSeq": lastSeq, "resumeSeq": resumeSeq,
 	})
 }
 
diff --git a/internal/store/messages.go b/internal/store/messages.go
index 9349ed8..8aaecec 100644
--- a/internal/store/messages.go
+++ b/internal/store/messages.go
@@ -338,6 +338,17 @@ func (s *Store) LastEventSeq(conversationID string) (int64, error) {
 	return seq.Int64, nil
 }
 
+// FirstRunEventSeq 返回这个 run 在会话事件流里的第一条 seq。
+// 没有事件时 ok 为 false。调用方用 seq-1 作为重放游标。
+func (s *Store) FirstRunEventSeq(conversationID, runID string) (seq int64, ok bool, err error) {
+	var got sql.NullInt64
+	err = s.db.QueryRow(s.q(`SELECT MIN(seq) FROM events WHERE conversation_id=? AND run_id=?`), conversationID, runID).Scan(&got)
+	if err != nil || !got.Valid {
+		return 0, false, err
+	}
+	return got.Int64, true, nil
+}
+
 func newID(kind string) string {
 	b := make([]byte, 6)
 	rand.Read(b)