diff --git a/layout_test.go b/layout_test.go
index 8380e3e..91faddc 100644
--- a/layout_test.go
+++ b/layout_test.go
@@ -87,6 +87,60 @@ func TestRelayoutWidthScalesWithFontSize(t *testing.T) {
 	}
 }
 
+// 多分段（断流重连）拼接时，remapJsonlTimes 只改时间、保留各段自己算的弹道，
+// 两段各自都从 0 号弹道开始排，时间压缩到同一条轴之后必然互相压。重排按拼接后
+// 的时间轴统一分配，这种跨段冲突也会一并消掉。
+func TestRelayoutFixesConcatenatedSegmentConflict(t *testing.T) {
+	meta := danmuMeta{PlayResX: 1920, PlayResY: 1080, FontSize: 48}
+	mk := func(base float64) []danmuRecord {
+		var out []danmuRecord
+		for i := 0; i < 12; i++ {
+			out = append(out, danmuRecord{
+				Time:    base + float64(i)*0.4,
+				UID:     int64(3000 + i),
+				Name:    "观众",
+				Content: "断流前后各自的弹幕",
+			})
+		}
+		return out
+	}
+	// 两段各自从 0 秒开始排（录制时就是这样），拼接后第二段紧接第一段
+	first := mk(0)
+	relayoutLanes(first, meta)
+	second := mk(4.8)
+	relayoutLanes(second, meta)
+	records := append(append([]danmuRecord{}, first...), second...)
+
+	// 前提：这种拼法本来就撞（第二段的 0 号弹道紧接第一段的 0 号弹道）
+	if overlaps := countLaneOverlaps(records, meta); overlaps == 0 {
+		t.Fatal("两段直接拼起来本应有同弹道冲突，用例前提不成立")
+	}
+
+	relayoutLanes(records, meta)
+
+	if overlaps := countLaneOverlaps(records, meta); overlaps != 0 {
+		t.Errorf("重排后仍有 %d 条同弹道冲突", overlaps)
+	}
+}
+
+// 按渲染时的公式统计同弹道追尾条数
+func countLaneOverlaps(records []danmuRecord, meta danmuMeta) int {
+	show := int64(danmuShowSeconds * 1e9)
+	resX := int64(meta.PlayResX)
+	last := map[int]int64{} // 弹道 → 上一条的让位时刻
+	over := 0
+	for _, r := range records {
+		total := int64(avatarSize(meta.FontSize)+avatarGap(meta.FontSize)) + int64(r.Width)
+		rel := int64(r.Time * 1e9)
+		emerge := rel + total*show/(resX+total)
+		if prev, ok := last[r.Lane]; ok && rel < prev {
+			over++
+		}
+		last[r.Lane] = emerge
+	}
+	return over
+}
+
 // 密集弹幕（弹道信息全是坏的：lane 都是 0、width 都是 0）重排后不应再有追尾，
 // 也不该超过弹道行数上限
 func TestRelayoutNoOverlapOnDenseInput(t *testing.T) {
diff --git a/recordjsonl_test.go b/recordjsonl_test.go
new file mode 100644
index 0000000..88e0b38
--- /dev/null
+++ b/recordjsonl_test.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"bufio"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/orzogc/acfundanmu"
+)
+
+// 用真正的录制写入器（danmuWriter）产生 jsonl，再按合并的流程重排一遍，
+// 验证「本程序自己录下来的弹幕」合出来和以前一模一样（弹道、宽度都不变）。
+// 这也是手动合并与自动合并的分水岭：录制侧写文件完全不经过 relayoutLanes，
+// 只有合并渲染前会重排，所以磁盘上的 .ass/.nick.ass/.jsonl 一个字节都不变。
+func TestLiveRecordingPathUnaffected(t *testing.T) {
+	dir := t.TempDir()
+	cfg := acfundanmu.SubConfig{Title: "测试直播", PlayResX: 1920, PlayResY: 1080,
+		FontSize: 48, StartTime: 1700000000000000000}
+	ass := filepath.Join(dir, "live.ass")
+	w := newDanmuWriter("liveid", "stream", cfg, ass)
+
+	texts := []string{"来啦", "这首歌好听", "主播加油啊", "打卡打卡", "哈哈哈哈哈哈哈哈哈",
+		"这条弹幕稍微长一点看看弹道到底怎么排"}
+	for i := 0; i < 500; i++ {
+		relMs := int64(i) * 220 // 平均 0.22 秒一条，够密集
+		c := &acfundanmu.Comment{Content: texts[i%len(texts)]}
+		c.SendTime = (cfg.StartTime + relMs*1e6) / 1e6
+		c.UserID = int64(2000 + i%9)
+		c.Nickname = "观众" + string(rune('A'+i%9))
+		c.Avatar = "http://example.invalid/a.png"
+		w.write(c)
+	}
+	w.close()
+
+	f, err := os.Open(filepath.Join(dir, "live.jsonl"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	sc.Buffer(make([]byte, 1<<20), 1<<20)
+	var meta danmuMeta
+	first := true
+	var recs []danmuRecord
+	for sc.Scan() {
+		if first {
+			json.Unmarshal(sc.Bytes(), &meta)
+			first = false
+			continue
+		}
+		var r danmuRecord
+		if json.Unmarshal(sc.Bytes(), &r) == nil {
+			recs = append(recs, r)
+		}
+	}
+	type snap struct{ lane, width int }
+	before := make([]snap, len(recs))
+	for i, r := range recs {
+		before[i] = snap{r.Lane, r.Width}
+	}
+
+	relayoutLanes(recs, meta)
+
+	laneDiff, widthDiff := 0, 0
+	for i, r := range recs {
+		if r.Lane != before[i].lane {
+			laneDiff++
+			if laneDiff <= 3 {
+				t.Logf("第 %d 条弹道变了：%d → %d", i, before[i].lane, r.Lane)
+			}
+		}
+		if r.Width != before[i].width {
+			widthDiff++
+		}
+	}
+	t.Logf("录制产生 %d 条弹幕（含空内容 %d 条），重排后弹道变化 %d 条、宽度变化 %d 条",
+		len(recs), countEmpty(recs), laneDiff, widthDiff)
+	if laneDiff != 0 || widthDiff != 0 {
+		t.Errorf("正常录制的弹幕重排后不应有任何变化")
+	}
+}
+
+func countEmpty(recs []danmuRecord) int {
+	n := 0
+	for _, r := range recs {
+		if r.Content == "" {
+			n++
+		}
+	}
+	return n
+}