From 366c05e4c33231283c1a0b28e9b1eca4aea02603 Mon Sep 17 00:00:00 2001
From: OpenIM-Gordon <46924906+FGadvancer@users.noreply.github.com>
Date: Thu, 17 Sep 2026 18:32:53 +0800
Subject: [PATCH] fix(msg): correct gap message document limit

---
 pkg/common/storage/model/msg.go      |  2 +-
 pkg/common/storage/model/msg_test.go | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 pkg/common/storage/model/msg_test.go

diff --git a/pkg/common/storage/model/msg.go b/pkg/common/storage/model/msg.go
index 2bb4882f7..aeaf866ed 100644
--- a/pkg/common/storage/model/msg.go
+++ b/pkg/common/storage/model/msg.go
@@ -133,7 +133,7 @@ func (*MsgDocModel) GetMsgIndex(seq int64) int64 {
 }
 
 func (*MsgDocModel) GetLimitForSingleDoc(seq int64) int64 {
-	return seq % singleGocMsgNum
+	return (seq - 1) % singleGocMsgNum
 }
 
 func (*MsgDocModel) indexGen(conversationID string, seqSuffix int64) string {
diff --git a/pkg/common/storage/model/msg_test.go b/pkg/common/storage/model/msg_test.go
new file mode 100644
index 000000000..0a406a172
--- /dev/null
+++ b/pkg/common/storage/model/msg_test.go
@@ -0,0 +1,12 @@
+package model
+
+import "testing"
+
+func TestMsgDocModelGetLimitForSingleDoc(t *testing.T) {
+	model := new(MsgDocModel)
+	for _, test := range []struct{ seq, want int64 }{{1, 0}, {99, 98}, {100, 99}, {101, 0}} {
+		if got := model.GetLimitForSingleDoc(test.seq); got != test.want {
+			t.Errorf("GetLimitForSingleDoc(%d) = %d, want %d", test.seq, got, test.want)
+		}
+	}
+}