diff --git a/frontend/src/composables/useChart.ts b/frontend/src/composables/useChart.ts
index 9846ecf..d86578d 100644
--- a/frontend/src/composables/useChart.ts
+++ b/frontend/src/composables/useChart.ts
@@ -4,9 +4,18 @@ import * as echarts from 'echarts'
 
 export function useChart(el: Ref<HTMLDivElement | undefined>) {
   let chart: echarts.ECharts | null = null
+  let ro: ResizeObserver | null = null
+
+  function ensureChart(): void {
+    if (!chart && el.value) chart = echarts.init(el.value)
+  }
 
   function setOption(option: echarts.EChartsCoreOption): void {
+    ensureChart()
     chart?.setOption(option, true)
+    // 数据通常在容器布局完成后才到（父组件异步拉取），此处同步一次尺寸，
+    // 避免 canvas 停在 init 时的窄宽（tab/初始化偏早导致）。
+    chart?.resize()
   }
 
   function resize(): void {
@@ -14,12 +23,18 @@ export function useChart(el: Ref<HTMLDivElement | undefined>) {
   }
 
   onMounted(() => {
-    if (el.value) chart = echarts.init(el.value)
+    ensureChart()
+    // ResizeObserver: 容器拿到真实宽度 / tab 切换 / 窗口变化时自动 resize
+    if (el.value && typeof ResizeObserver !== 'undefined') {
+      ro = new ResizeObserver(() => chart?.resize())
+      ro.observe(el.value)
+    }
     window.addEventListener('resize', resize)
   })
 
   onUnmounted(() => {
     window.removeEventListener('resize', resize)
+    ro?.disconnect()
     chart?.dispose()
     chart = null
   })