diff --git a/web/display/src/pages/Line.tsx b/web/display/src/pages/Line.tsx
index afb43cb..05fa62d 100644
--- a/web/display/src/pages/Line.tsx
+++ b/web/display/src/pages/Line.tsx
@@ -55,6 +55,8 @@ interface ChartDef {
   group: MetricGroup
   /** 占满一行。 */
   wide?: boolean
+  /** 没有才是好的指标：整段为 0 时图上显示的说明 */
+  quiet?: string
 }
 
 const GROUPS = [
@@ -66,10 +68,10 @@ const GROUPS = [
 const CHARTS: ChartDef[] = [
   { id: 'rtt', title: '延迟', group: 'quic', unit: 'ms', series: [{ key: 'rtt.p50', label: 'p50', color: '--chart-1' }, { key: 'rtt.p95', label: 'p95', color: '--chart-2' }, { key: 'rtt.p99', label: 'p99', color: '--chart-3' }] },
   { id: 'jitter', title: '抖动（p95）', group: 'quic', unit: 'ms', series: [{ key: 'jitter.up.p95', label: '去程', color: '--chart-2' }, { key: 'jitter.down.p95', label: '回程', color: '--chart-1' }] },
-  { id: 'loss', title: '丢包', group: 'quic', unit: '%', series: [{ key: 'loss.up', label: '去程', color: '--chart-2' }, { key: 'loss.down', label: '回程', color: '--chart-3' }, { key: 'loss.total', label: '合计', color: '--chart-1', dash: [4, 3] }] },
-  { id: 'loss-runs', title: '最长连续丢包', group: 'quic', unit: '包', series: [{ key: 'loss.run.up_max', label: '去程', color: '--chart-2' }, { key: 'loss.run.down_max', label: '回程', color: '--chart-3' }] },
+  { id: 'loss', title: '丢包', group: 'quic', unit: '%', fill: true, quiet: '✓ 这段时间没有丢包', series: [{ key: 'loss.up', label: '去程', color: '--chart-2' }, { key: 'loss.down', label: '回程', color: '--chart-3' }, { key: 'loss.total', label: '合计', color: '--chart-1', dash: [4, 3] }] },
+  { id: 'loss-runs', title: '最长连续丢包', group: 'quic', unit: '包', fill: true, quiet: '✓ 这段时间没有连续丢包', series: [{ key: 'loss.run.up_max', label: '去程', color: '--chart-2' }, { key: 'loss.run.down_max', label: '回程', color: '--chart-3' }] },
   { id: 'tcp', title: '往返时延（RTT）', group: 'tcp-connect', unit: 'ms', series: [{ key: 'tcp.rtt.p50', label: 'p50', color: '--chart-1' }, { key: 'tcp.rtt.p95', label: 'p95', color: '--chart-2' }, { key: 'tcp.rtt.max', label: '最大', color: '--chart-3' }] },
-  { id: 'retrans', title: '重传率', group: 'tcp-connect', unit: '%', series: [{ key: 'tcp.retrans.up', label: '去程', color: '--chart-2' }, { key: 'tcp.retrans.down', label: '回程', color: '--chart-3' }, { key: 'tcp.retrans', label: '合计', color: '--chart-1', dash: [4, 3] }] },
+  { id: 'retrans', title: '重传率', group: 'tcp-connect', unit: '%', fill: true, quiet: '✓ 这段时间没有重传', series: [{ key: 'tcp.retrans.up', label: '去程', color: '--chart-2' }, { key: 'tcp.retrans.down', label: '回程', color: '--chart-3' }, { key: 'tcp.retrans', label: '合计', color: '--chart-1', dash: [4, 3] }] },
   { id: 'connect-time', title: '建连耗时（p95）', group: 'tcp-connect', unit: 'ms', series: [{ key: 'connect.tcp_ms.p95', label: 'TCP 建连', color: '--chart-1' }, { key: 'connect.tls_ms.p95', label: 'TLS 握手', color: '--chart-2' }] },
   { id: 'connect-ok', title: '建连成功率', group: 'tcp-connect', unit: '%', zero: false, series: [{ key: 'connect.success', label: '成功率', color: '--chart-3' }] },
   { id: 'score', title: '综合评分', group: 'score', wide: true, unit: '', series: [{ key: 'score.reality', label: 'REALITY', color: '--chart-1' }, { key: 'score.hy2', label: 'Hy2', color: '--chart-2' }, { key: 'score.mc', label: 'MC', color: '--chart-4' }, { key: 'score.base', label: '综合', color: '--chart-5', dash: [4, 3] }] },
@@ -177,7 +179,7 @@ export function Line() {
                     ]
                   : raw.map(({ x, values }) => ({ label: x.label, values, color: x.color, dash: x.dash, fill: def.fill }))
               if (!list.some((x) => x.values.some((v) => v !== null))) return null
-              return { def, node: <TimeChart t={s.t} series={list} unit={def.unit} gaps={gaps} zero={def.zero !== false} height={metricGroup === 'quic' ? 220 : def.wide ? 230 : 190} /> }
+              return { def, node: <TimeChart t={s.t} series={list} unit={def.unit} quiet={def.quiet} gaps={gaps} zero={def.zero !== false} height={metricGroup === 'quic' ? 220 : def.wide ? 230 : 190} /> }
             })
             return { group, cards: cards.filter((c): c is NonNullable<typeof c> => c !== null) }
           }).filter((g) => g.cards.length > 0)
diff --git a/web/shared/charts/TimeChart.tsx b/web/shared/charts/TimeChart.tsx
index 0779646..7c84c9e 100644
--- a/web/shared/charts/TimeChart.tsx
+++ b/web/shared/charts/TimeChart.tsx
@@ -26,6 +26,8 @@ interface Props {
   gaps?: { from: number; to: number }[]
   /** 为真时 `t` 是「从起点算起的毫秒数」而不是 Unix 毫秒：横轴显示 0:00、0:15…，用来把两段时间叠在一起比。 */
   offset?: boolean
+  /** 丢包、重传这类「没有才是好」的图：整段都是 0（或没有值）时，在图上盖一句说明，而不是留一条贴着底边的平线。 */
+  quiet?: string
 }
 
 /** 偏移量（毫秒）→ h:mm:ss / m:ss。 */
@@ -38,6 +40,24 @@ export function fmtOffset(ms: number): string {
   return h > 0 ? `${h}:${two(m)}${sec ? ':' + two(sec) : ''}` : `${m}:${two(sec)}`
 }
 
+/** 有值的格子不到三分之一（而且至少有一个）算稀疏。 */
+function isSparse(values: (number | null)[]): boolean {
+  const filled = values.filter((v) => v !== null).length
+  return filled > 0 && filled < values.length / 3
+}
+
+/**
+ * Y 轴范围：默认从 0 开始，上面留 8%。百分比的轴不会超过 100%（成功率贴着 100% 时不再出现 100.75% 这种刻度），
+ * 一条平线（最大等于最小）也给出可读的范围。
+ */
+function yRange(min: number, max: number, zero: boolean, unit: string): [number, number] {
+  const percent = unit === '%'
+  const lo = zero ? Math.min(0, min) : percent ? Math.max(0, min - Math.max(1, (max - min) * 0.2)) : min
+  let hi = max <= min ? min + (percent ? Math.max(1, Math.abs(min) * 0.01) : 1) : max + (max - min) * 0.08
+  if (percent && max <= 100) hi = Math.min(100, hi)
+  return [lo, hi > lo ? hi : lo + 1]
+}
+
 function cssVar(name: string): string {
   return getComputedStyle(document.documentElement).getPropertyValue(name).trim()
 }
@@ -61,7 +81,7 @@ function formatValue(v: number | null | undefined, unit: string): string {
  * - 在图上拖动选一段放大预览，双击或点「还原」恢复；数据刷新时保持放大的区间；
  * - 鼠标悬停显示这个时刻每条线的值。
  */
-export function TimeChart({ t, series, height = 220, unit = '', zero = true, gaps = [], offset = false }: Props) {
+export function TimeChart({ t, series, height = 220, unit = '', zero = true, gaps = [], offset = false, quiet }: Props) {
   const host = useRef<HTMLDivElement>(null)
   const tip = useRef<HTMLDivElement>(null)
   const plot = useRef<uPlot | null>(null)
@@ -70,7 +90,10 @@ export function TimeChart({ t, series, height = 220, unit = '', zero = true, gap
   // 数据变了（轮询、实时）只更新数据，不重建图：重建会闪一下，还会丢掉鼠标位置
   const latest = useRef({ t, series, gaps })
   latest.current = { t, series, gaps }
-  const structure = JSON.stringify([series.map((x) => [x.label, x.color, x.dash, x.fill, x.faint]), unit, zero, offset, height])
+  // 稀疏的序列（例如每分钟只有几次的建连）：大部分格子是空的，单独的一个点画成线就看不见，所以画出点并把点连起来
+  const sparse = series.map((x) => isSparse(x.values))
+  const allQuiet = quiet !== undefined && series.filter((x) => !x.faint).every((x) => x.values.every((v) => v === null || v <= 0))
+  const structure = JSON.stringify([series.map((x, i) => [x.label, x.color, x.dash, x.fill, x.faint, sparse[i]]), unit, zero, offset, height])
   const dataOf = (): AlignedData => [latest.current.t.map((v) => v / 1000), ...latest.current.series.map((x) => x.values.map((v) => (v === null ? null : v)))]
 
   const reset = useCallback(() => {
@@ -97,7 +120,7 @@ export function TimeChart({ t, series, height = 220, unit = '', zero = true, gap
         select: { show: true, left: 0, top: 0, width: 0, height: 0 },
         scales: {
           x: { time: !offset, range: (_u, min, max) => (zoom.current ? [zoom.current.min, zoom.current.max] : [min, max]) },
-          y: { range: (_u, min, max) => [zero ? Math.min(0, min) : min, max <= min ? min + 1 : max + (max - min) * 0.08] },
+          y: { range: (_u, min, max) => yRange(min, max, zero, unit) },
         },
         axes: [
           { stroke: axis, grid: { stroke: grid, width: 1 }, ticks: { stroke: grid }, font, ...(offset ? { values: (_u: uPlot, ticks: number[]) => ticks.map((v) => fmtOffset(v * 1000)) } : {}) },
@@ -113,8 +136,8 @@ export function TimeChart({ t, series, height = 220, unit = '', zero = true, gap
               width: s.faint ? 1 : 1.8,
               dash: s.dash,
               fill: s.fill ? color + '22' : undefined,
-              spanGaps: false,
-              points: { show: false },
+              spanGaps: sparse[series.indexOf(s)],
+              points: { show: sparse[series.indexOf(s)], size: 5 },
             }
           }),
         ],
@@ -218,7 +241,10 @@ export function TimeChart({ t, series, height = 220, unit = '', zero = true, gap
           )}
         </span>
       </div>
-      <div ref={host} className="chart" />
+      <div className="chart-body">
+        <div ref={host} className="chart" />
+        {allQuiet ? <div className="chart-quiet">{quiet}</div> : null}
+      </div>
       <div ref={tip} className="chart-tip" />
     </div>
   )
diff --git a/web/shared/theme/base.css b/web/shared/theme/base.css
index 3b69c20..051bf05 100644
--- a/web/shared/theme/base.css
+++ b/web/shared/theme/base.css
@@ -1088,3 +1088,20 @@ pre.code {
   align-items: center;
   gap: 4px;
 }
+
+/* 「没有才是好」的图整段为 0 时：盖一句说明，图的坐标轴留着，说明在绘图区中间 */
+.chart-body {
+  position: relative;
+}
+
+.chart-quiet {
+  position: absolute;
+  inset: 0 0 28px 56px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: var(--app-ok);
+  font-size: 14px;
+  font-weight: 600;
+  pointer-events: none;
+}