diff --git a/frontend-web/src/components/workspace/admin/concurrency-monitor.tsx b/frontend-web/src/components/workspace/admin/concurrency-monitor.tsx
index 51d6e6b8..dec77b11 100644
--- a/frontend-web/src/components/workspace/admin/concurrency-monitor.tsx
+++ b/frontend-web/src/components/workspace/admin/concurrency-monitor.tsx
@@ -9,7 +9,7 @@ import {
   Square,
   Zap,
 } from "lucide-react";
-import { useMemo, useState } from "react";
+import { useId, useMemo, useState } from "react";
 import { toast } from "sonner";
 
 import { Badge } from "@/components/ui/badge";
@@ -60,39 +60,117 @@ interface LineSeries {
   values: (number | null)[];
 }
 
-/** Minimal dependency-free SVG line chart (1–2 series + area under the first). */
+/** Round a value up to a "nice" axis ceiling (1 / 2 / 5 × 10ⁿ). */
+function niceCeil(v: number): number {
+  if (!Number.isFinite(v) || v <= 0) return 1;
+  const exp = Math.floor(Math.log10(v));
+  const base = 10 ** exp;
+  const f = v / base;
+  const nice = f <= 1 ? 1 : f <= 2 ? 2 : f <= 5 ? 5 : 10;
+  return nice * base;
+}
+
+/**
+ * Build distinct axis ticks from the data max. For integer series (并发量) this
+ * yields whole-number ticks with no duplicate labels (fixes the「0 0 0 1 1」
+ * axis when the max is 1); for floats it uses a nice ceiling at quarters.
+ */
+function buildTicks(dataMax: number, integer: boolean): number[] {
+  if (!Number.isFinite(dataMax) || dataMax <= 0) return [0, 1];
+  if (integer) {
+    const niceMax = Math.max(1, Math.ceil(dataMax));
+    const step = Math.max(1, Math.ceil(niceMax / 4)); // ≤5 integer ticks
+    const top = Math.ceil(niceMax / step) * step;
+    const ticks: number[] = [];
+    for (let v = 0; v <= top; v += step) ticks.push(v);
+    return ticks;
+  }
+  const niceMax = niceCeil(dataMax);
+  return [0, 0.25, 0.5, 0.75, 1].map((r) => niceMax * r);
+}
+
+function fmtAxis(v: number, integer: boolean): string {
+  if (integer) return String(Math.round(v));
+  if (v === 0) return "0";
+  return v < 10 ? v.toFixed(1) : String(Math.round(v));
+}
+
+/** Last non-null value of a series (for the legend's current reading). */
+function latestOf(values: (number | null)[]): number | null {
+  for (let i = values.length - 1; i >= 0; i -= 1) {
+    if (values[i] != null) return values[i] as number;
+  }
+  return null;
+}
+
+/** Minimal dependency-free SVG line chart: legend + 1–2 series + area + caption. */
 function LineChart({
   labels,
   series,
   unit,
+  integer = false,
+  note,
   emptyHint,
 }: {
   labels: string[];
   series: LineSeries[];
   unit: string;
+  integer?: boolean;
+  note?: string;
   emptyHint: string;
 }) {
+  const gradId = `cm-area-${useId().replace(/:/g, "")}`;
   const width = 760;
   const height = 220;
-  const pad = { top: 18, right: 16, bottom: 26, left: 40 };
+  const pad = { top: 16, right: 16, bottom: 26, left: 44 };
   const cw = width - pad.left - pad.right;
   const ch = height - pad.top - pad.bottom;
+  const n = labels.length;
 
   const allValues = series.flatMap((s) => s.values.filter((v): v is number => v != null));
-  const max = Math.max(1, ...allValues);
-  const n = labels.length;
+  const dataMax = allValues.length ? Math.max(...allValues) : 0;
+  const ticks = buildTicks(dataMax, integer);
+  const axisMax = ticks[ticks.length - 1] || 1;
+
+  // Legend always renders (even with no data) so the lines are self-explanatory.
+  const legend = (
+    <div className="mb-2 flex flex-wrap items-center gap-x-4 gap-y-1">
+      {series.map((s) => {
+        const latest = latestOf(s.values);
+        return (
+          <span key={s.name} className="flex items-center gap-1.5 text-xs text-[#5F6368] dark:text-slate-300">
+            <span className="inline-block h-[3px] w-4 rounded-full" style={{ backgroundColor: s.color }} />
+            {s.name}
+            {latest != null && (
+              <span className="font-semibold tabular-nums text-[#231815] dark:text-white">
+                {Number.isInteger(latest) ? latest : latest.toFixed(1)}
+                {unit}
+              </span>
+            )}
+          </span>
+        );
+      })}
+    </div>
+  );
+
+  const caption = note ? (
+    <p className="mt-2 text-[11px] leading-4 text-[#8B6B6B] dark:text-[#7FACF2]">{note}</p>
+  ) : null;
 
   if (n === 0) {
     return (
-      <div className="flex h-[220px] items-center justify-center text-sm text-[#5F6368] dark:text-slate-400">
-        {emptyHint}
+      <div>
+        {legend}
+        <div className="flex h-[160px] items-center justify-center rounded-lg border border-dashed border-[#F1D6D6] text-sm text-[#5F6368] dark:border-[#213D5E] dark:text-slate-400">
+          {emptyHint}
+        </div>
+        {caption}
       </div>
     );
   }
 
   const xFor = (i: number) => pad.left + (n <= 1 ? cw / 2 : (i / (n - 1)) * cw);
-  const yFor = (v: number) => pad.top + ch - (v / max) * ch;
-  const grid = [0, 0.25, 0.5, 0.75, 1];
+  const yFor = (v: number) => pad.top + ch - (v / axisMax) * ch;
 
   const linePath = (vals: (number | null)[]) => {
     let d = "";
@@ -119,63 +197,66 @@ function LineChart({
   const labelStep = Math.max(1, Math.ceil(n / 7));
 
   return (
-    <svg viewBox={`0 0 ${width} ${height}`} className="w-full" role="img" aria-label="时序折线图">
-      <defs>
-        <linearGradient id="cm-area" x1="0" x2="0" y1="0" y2="1">
-          <stop offset="0%" stopColor={first?.color ?? "#C1121F"} stopOpacity="0.18" />
-          <stop offset="100%" stopColor={first?.color ?? "#C1121F"} stopOpacity="0.02" />
-        </linearGradient>
-      </defs>
-      {grid.map((r) => {
-        const y = pad.top + ch * r;
-        return (
-          <g key={r}>
-            <line
-              x1={pad.left}
-              x2={width - pad.right}
-              y1={y}
-              y2={y}
-              stroke="currentColor"
-              className="text-[#E5E7EB] dark:text-[#3F3F46]"
-              strokeWidth="1"
-            />
-            <text x={6} y={y + 4} className="fill-[#9CA3AF] text-[10px]">
-              {Math.round(max * (1 - r))}
+    <div>
+      {legend}
+      <svg viewBox={`0 0 ${width} ${height}`} className="w-full" role="img" aria-label="时序折线图">
+        <defs>
+          <linearGradient id={gradId} x1="0" x2="0" y1="0" y2="1">
+            <stop offset="0%" stopColor={first?.color ?? "#C1121F"} stopOpacity="0.18" />
+            <stop offset="100%" stopColor={first?.color ?? "#C1121F"} stopOpacity="0.02" />
+          </linearGradient>
+        </defs>
+        {ticks.map((t) => {
+          const y = yFor(t);
+          return (
+            <g key={t}>
+              <line
+                x1={pad.left}
+                x2={width - pad.right}
+                y1={y}
+                y2={y}
+                stroke="currentColor"
+                className="text-[#E5E7EB] dark:text-[#3F3F46]"
+                strokeWidth="1"
+              />
+              <text x={pad.left - 6} y={y + 3} textAnchor="end" className="fill-[#9CA3AF] text-[10px]">
+                {fmtAxis(t, integer)}
+              </text>
+            </g>
+          );
+        })}
+        {areaPath && <path d={areaPath} fill={`url(#${gradId})`} />}
+        {series.map((s) => (
+          <path
+            key={s.name}
+            d={linePath(s.values)}
+            fill="none"
+            stroke={s.color}
+            strokeWidth="2"
+            strokeLinecap="round"
+            strokeLinejoin="round"
+          />
+        ))}
+        {labels.map((label, i) => {
+          if (i !== 0 && i !== n - 1 && i % labelStep !== 0) return null;
+          return (
+            <text key={`${label}-${i}`} x={xFor(i)} y={height - 8} textAnchor="middle" className="fill-[#6B7280] text-[10px]">
+              {label}
             </text>
-          </g>
-        );
-      })}
-      {areaPath && <path d={areaPath} fill="url(#cm-area)" />}
-      {series.map((s) => (
-        <path
-          key={s.name}
-          d={linePath(s.values)}
-          fill="none"
-          stroke={s.color}
-          strokeWidth="2"
-          strokeLinecap="round"
-          strokeLinejoin="round"
-        />
-      ))}
-      {labels.map((label, i) => {
-        if (i !== 0 && i !== n - 1 && i % labelStep !== 0) return null;
-        return (
-          <text key={`${label}-${i}`} x={xFor(i)} y={height - 8} textAnchor="middle" className="fill-[#6B7280] text-[10px]">
-            {label}
-          </text>
-        );
-      })}
-      {/* hover dots with native tooltip */}
-      {series.map((s) =>
-        s.values.map((v, i) =>
-          v == null ? null : (
-            <circle key={`${s.name}-${i}`} cx={xFor(i)} cy={yFor(v)} r={2.5} fill={s.color}>
-              <title>{`${labels[i]} · ${s.name}: ${v}${unit}`}</title>
-            </circle>
+          );
+        })}
+        {series.map((s) =>
+          s.values.map((v, i) =>
+            v == null ? null : (
+              <circle key={`${s.name}-${i}`} cx={xFor(i)} cy={yFor(v)} r={2.5} fill={s.color}>
+                <title>{`${labels[i]} · ${s.name}: ${v}${unit}`}</title>
+              </circle>
+            ),
           ),
-        ),
-      )}
-    </svg>
+        )}
+      </svg>
+      {caption}
+    </div>
   );
 }
 
@@ -401,7 +482,7 @@ export function ConcurrencyMonitorPanel() {
 
           {/* charts */}
           <div className="grid gap-3 xl:grid-cols-2">
-            <ChartCard icon={Gauge} title="并发量（系统压力）" subtitle="峰值 / 平均并发调用数">
+            <ChartCard icon={Gauge} title="并发量（系统压力）" subtitle={`每${granularity === "hour" ? "小时" : "分钟"}一个点`}>
               {concurrency.isLoading ? (
                 <div className="flex h-[220px] items-center justify-center text-sm text-[#5F6368] dark:text-slate-400">
                   <Loader2 className="mr-2 size-4 animate-spin" /> 加载中
@@ -410,12 +491,14 @@ export function ConcurrencyMonitorPanel() {
                 <LineChart
                   labels={concurrencyChart.labels}
                   series={concurrencyChart.series}
-                  unit=""
-                  emptyHint="暂无并发采样数据（采样关闭或时间窗口内无记录）"
+                  unit=" 个"
+                  integer
+                  note="红线=该时段同时进行的最多调用数（峰值）；橙线=该时段平均值。数值越高、越靠上，说明同时打大模型的请求越多、系统压力越大。"
+                  emptyHint="暂无并发采样数据（需打开「后台采样」开关后才开始记录）"
                 />
               )}
             </ChartCard>
-            <ChartCard icon={Zap} title="大模型出字速度" subtitle="tokens/秒（越低说明模型越慢）">
+            <ChartCard icon={Zap} title="大模型出字速度" subtitle={`每${granularity === "hour" ? "小时" : "分钟"}一个点`}>
               {tokenSpeed.isLoading ? (
                 <div className="flex h-[220px] items-center justify-center text-sm text-[#5F6368] dark:text-slate-400">
                   <Loader2 className="mr-2 size-4 animate-spin" /> 加载中
@@ -425,6 +508,7 @@ export function ConcurrencyMonitorPanel() {
                   labels={tokenChart.labels}
                   series={tokenChart.series}
                   unit=" t/s"
+                  note="蓝线=该时段所有大模型调用的平均出字速度（tokens/秒，越高越快）；紫线=该时段最慢的一次调用。某段时间线明显下凹，说明那会儿模型/供应商变慢，是压力或瓶颈所在。"
                   emptyHint="暂无大模型调用记录"
                 />
               )}