diff --git a/internal/store/sms_restart_test.go b/internal/store/sms_restart_test.go
new file mode 100644
index 0000000..5fdfe33
--- /dev/null
+++ b/internal/store/sms_restart_test.go
@@ -0,0 +1,121 @@
+package store
+
+import (
+	"context"
+	"encoding/json"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestLongSMSReassemblySurvivesServiceRestart(t *testing.T) {
+	ctx := context.Background()
+	path := filepath.Join(t.TempDir(), "vocat.db")
+	const (
+		deviceID = "dajiang"
+		imei     = "867394042309830"
+		peer     = "+447700900123"
+	)
+	messageID := StableConcatMessageID("ims", imei, deviceID, peer, 27, 2)
+
+	database, err := Open(ctx, path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustSaveDevice(t, database, deviceID, "大疆")
+	first, err := database.SaveSMSMessage(ctx, SMSMessage{
+		MessageID: messageID, DeviceID: deviceID, ModemIMEI: imei, IMSI: "23433",
+		Peer: peer, Direction: "inbound", Body: "第一段：安全提醒，",
+		Timestamp: time.Unix(1_700_000_000, 0).UTC(), Status: "received", Source: "ims",
+		PartsTotal: 2, Extra: concatExtra(t, 27, 2, 1),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ConcatSMSReadyToNotify(first.MessageID, first.Extra) {
+		t.Fatal("partial message must not be ready before restart")
+	}
+	if err := database.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	database, err = Open(ctx, path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer database.Close()
+	second, err := database.SaveSMSMessage(ctx, SMSMessage{
+		MessageID: messageID, DeviceID: deviceID, ModemIMEI: imei, IMSI: "23433",
+		Peer: peer, Direction: "inbound", Body: "第二段：请通过官方渠道核实。",
+		Timestamp: time.Unix(1_700_000_030, 0).UTC(), Status: "received", Source: "ims",
+		PartsTotal: 2, Extra: concatExtra(t, 27, 2, 2),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if second.Body != "第一段：安全提醒，第二段：请通过官方渠道核实。" ||
+		!ConcatSMSReadyToNotify(second.MessageID, second.Extra) {
+		t.Fatalf("reassembled message after restart = %#v", second)
+	}
+	messages, err := database.ListSMSMessages(ctx, SMSFilter{DeviceID: deviceID})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(messages) != 1 || messages[0].ID != second.ID {
+		t.Fatalf("stored messages after restart = %#v, want one merged row", messages)
+	}
+	redelivered, err := database.SaveSMSMessage(ctx, SMSMessage{
+		MessageID: messageID, DeviceID: deviceID, ModemIMEI: imei, IMSI: "23433",
+		Peer: peer, Direction: "inbound", Body: "第二段：请通过官方渠道核实。",
+		Status: "received", Source: "ims", PartsTotal: 2, Extra: concatExtra(t, 27, 2, 2),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if redelivered.ID != second.ID || redelivered.Body != second.Body {
+		t.Fatalf("redelivery duplicated or changed message: %#v", redelivered)
+	}
+}
+
+func TestMultipartDeliveryReportsSurviveServiceRestart(t *testing.T) {
+	ctx := context.Background()
+	path := filepath.Join(t.TempDir(), "vocat.db")
+	database, err := Open(ctx, path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mustSaveDevice(t, database, "dajiang", "大疆")
+	extra := json.RawMessage(`{"transport":"ims","part_results":[{"reference":51},{"reference":52}]}`)
+	sent, err := database.SaveSMSMessage(ctx, SMSMessage{
+		MessageID: "ims-submit-restart", DeviceID: "dajiang", IMSI: "23433",
+		Peer: "+447700900123", Direction: "outbound", Body: "multipart",
+		Status: "accepted_by_ims", Source: "ims", PartsTotal: 2,
+		DeliveryState: "accepted_by_ims", Read: true, Extra: extra,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := database.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	database, err = Open(ctx, path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer database.Close()
+	first, err := database.ApplySMSDeliveryReport(ctx, SMSDeliveryReport{
+		DeviceID: "dajiang", IMSI: "23433", Peer: "+447700900123", Source: "ims",
+		MessageReference: 51, StatusCode: 0, DeliveryState: "delivered",
+	})
+	if err != nil || first.ID != sent.ID || first.DeliveryState != "pending_delivery_report" {
+		t.Fatalf("first report after restart = (%#v, %v)", first, err)
+	}
+	second, err := database.ApplySMSDeliveryReport(ctx, SMSDeliveryReport{
+		DeviceID: "dajiang", IMSI: "23433", Peer: "+447700900123", Source: "ims",
+		MessageReference: 52, StatusCode: 0, DeliveryState: "delivered",
+	})
+	if err != nil || second.ID != sent.ID || second.DeliveryState != "delivered" {
+		t.Fatalf("second report after restart = (%#v, %v)", second, err)
+	}
+}