diff --git a/data/modernization_feature_flags.json b/data/modernization_feature_flags.json
index 49f66a9..c01088d 100644
--- a/data/modernization_feature_flags.json
+++ b/data/modernization_feature_flags.json
@@ -6,6 +6,7 @@
     "/hold-overview": {"content_cutover_enabled": true},
     "/hold-detail": {"content_cutover_enabled": true},
     "/hold-history": {"content_cutover_enabled": true},
+    "/reject-history": {"content_cutover_enabled": false},
     "/resource": {"content_cutover_enabled": true},
     "/resource-history": {"content_cutover_enabled": true},
     "/qc-gate": {"content_cutover_enabled": true},
diff --git a/frontend/package.json b/frontend/package.json
index 7385b25..0465e5d 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -5,7 +5,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite --host",
-    "build": "vite build && cp ../src/mes_dashboard/static/dist/src/portal-shell/index.html ../src/mes_dashboard/static/dist/portal-shell.html && cp ../src/mes_dashboard/static/dist/src/tables/index.html ../src/mes_dashboard/static/dist/tables.html && cp ../src/mes_dashboard/static/dist/src/qc-gate/index.html ../src/mes_dashboard/static/dist/qc-gate.html && cp ../src/mes_dashboard/static/dist/src/wip-overview/index.html ../src/mes_dashboard/static/dist/wip-overview.html && cp ../src/mes_dashboard/static/dist/src/wip-detail/index.html ../src/mes_dashboard/static/dist/wip-detail.html && cp ../src/mes_dashboard/static/dist/src/hold-detail/index.html ../src/mes_dashboard/static/dist/hold-detail.html && cp ../src/mes_dashboard/static/dist/src/hold-overview/index.html ../src/mes_dashboard/static/dist/hold-overview.html && cp ../src/mes_dashboard/static/dist/src/hold-history/index.html ../src/mes_dashboard/static/dist/hold-history.html && cp ../src/mes_dashboard/static/dist/src/resource-status/index.html ../src/mes_dashboard/static/dist/resource-status.html && cp ../src/mes_dashboard/static/dist/src/resource-history/index.html ../src/mes_dashboard/static/dist/resource-history.html && cp ../src/mes_dashboard/static/dist/src/mid-section-defect/index.html ../src/mes_dashboard/static/dist/mid-section-defect.html",
+    "build": "vite build && cp ../src/mes_dashboard/static/dist/src/portal-shell/index.html ../src/mes_dashboard/static/dist/portal-shell.html && cp ../src/mes_dashboard/static/dist/src/tables/index.html ../src/mes_dashboard/static/dist/tables.html && cp ../src/mes_dashboard/static/dist/src/qc-gate/index.html ../src/mes_dashboard/static/dist/qc-gate.html && cp ../src/mes_dashboard/static/dist/src/wip-overview/index.html ../src/mes_dashboard/static/dist/wip-overview.html && cp ../src/mes_dashboard/static/dist/src/wip-detail/index.html ../src/mes_dashboard/static/dist/wip-detail.html && cp ../src/mes_dashboard/static/dist/src/hold-detail/index.html ../src/mes_dashboard/static/dist/hold-detail.html && cp ../src/mes_dashboard/static/dist/src/hold-overview/index.html ../src/mes_dashboard/static/dist/hold-overview.html && cp ../src/mes_dashboard/static/dist/src/hold-history/index.html ../src/mes_dashboard/static/dist/hold-history.html && cp ../src/mes_dashboard/static/dist/src/reject-history/index.html ../src/mes_dashboard/static/dist/reject-history.html && cp ../src/mes_dashboard/static/dist/src/resource-status/index.html ../src/mes_dashboard/static/dist/resource-status.html && cp ../src/mes_dashboard/static/dist/src/resource-history/index.html ../src/mes_dashboard/static/dist/resource-history.html && cp ../src/mes_dashboard/static/dist/src/mid-section-defect/index.html ../src/mes_dashboard/static/dist/mid-section-defect.html",
     "test": "node --test tests/*.test.js"
   },
   "devDependencies": {
diff --git a/frontend/src/query-tool/App.vue b/frontend/src/query-tool/App.vue
index 62016fe..bf238ba 100644
--- a/frontend/src/query-tool/App.vue
+++ b/frontend/src/query-tool/App.vue
@@ -192,17 +192,11 @@ async function handleResolveLots() {
     return;
   }
 
+  // Build tree only — don't auto-select or load detail data.
+  // User clicks a node to trigger detail/timeline loading on demand.
   await lotLineage.primeResolvedLots(lotResolve.resolvedLots.value);
-
-  const treeRootIds = lotLineage.treeRoots.value;
-  if (treeRootIds.length === 0) {
-    await lotDetail.setSelectedContainerId('');
-    lotLineage.clearSelection();
-    return;
-  }
-
-  // Auto-select all tree roots and load detail for their full subtrees
-  await handleSelectNodes(treeRootIds);
+  lotLineage.clearSelection();
+  lotDetail.clearTabData();
 }
 
 async function handleSelectNodes(containerIds) {
diff --git a/frontend/src/query-tool/components/LineageTreeChart.vue b/frontend/src/query-tool/components/LineageTreeChart.vue
index 3464065..2d4e284 100644
--- a/frontend/src/query-tool/components/LineageTreeChart.vue
+++ b/frontend/src/query-tool/components/LineageTreeChart.vue
@@ -145,113 +145,137 @@ function buildNode(cid, visited) {
   };
 }
 
-const echartsData = computed(() => {
+// Build each root into its own independent tree data
+const treesData = computed(() => {
   if (props.treeRoots.length === 0) {
     return [];
   }
 
-  const visited = new Set();
+  const globalVisited = new Set();
   return props.treeRoots
-    .map((rootId) => buildNode(rootId, visited))
+    .map((rootId) => buildNode(rootId, globalVisited))
     .filter(Boolean);
 });
 
-const hasData = computed(() => echartsData.value.length > 0);
+const hasData = computed(() => treesData.value.length > 0);
 
-function countNodes(nodes) {
-  let count = 0;
-  function walk(list) {
-    list.forEach((node) => {
-      count += 1;
-      if (node.children?.length > 0) {
-        walk(node.children);
-      }
-    });
+function countLeaves(node) {
+  if (!node.children || node.children.length === 0) {
+    return 1;
   }
-  walk(nodes);
-  return count;
+  return node.children.reduce((sum, child) => sum + countLeaves(child), 0);
 }
 
 const chartHeight = computed(() => {
-  const total = countNodes(echartsData.value);
-  const base = Math.max(300, Math.min(800, total * 28));
+  const totalLeaves = treesData.value.reduce((sum, tree) => sum + countLeaves(tree), 0);
+  const base = Math.max(300, Math.min(1200, totalLeaves * 36));
   return `${base}px`;
 });
 
+const TREE_SERIES_DEFAULTS = Object.freeze({
+  type: 'tree',
+  layout: 'orthogonal',
+  orient: 'LR',
+  expandAndCollapse: true,
+  initialTreeDepth: -1,
+  roam: 'move',
+  symbol: 'circle',
+  symbolSize: 10,
+  label: {
+    show: true,
+    position: 'right',
+    fontSize: 11,
+    color: '#334155',
+    overflow: 'truncate',
+    ellipsis: '…',
+    width: 160,
+  },
+  lineStyle: {
+    width: 1.5,
+    color: '#CBD5E1',
+    curveness: 0.5,
+  },
+  emphasis: {
+    focus: 'ancestor',
+    itemStyle: { borderWidth: 2 },
+    label: { fontWeight: 'bold' },
+  },
+  animationDuration: 350,
+  animationDurationUpdate: 300,
+});
+
 const chartOption = computed(() => {
-  if (!hasData.value) {
+  const trees = treesData.value;
+  if (trees.length === 0) {
     return null;
   }
 
-  return {
-    tooltip: {
-      trigger: 'item',
-      triggerOn: 'mousemove',
-      formatter(params) {
-        const data = params?.data;
-        if (!data) {
-          return '';
-        }
-        const val = data.value || {};
-        const lines = [`<b>${data.name}</b>`];
-        if (val.type === 'serial') {
-          lines.push('<span style="color:#64748B">成品序列號</span>');
-        } else if (val.type === 'root') {
-          lines.push('<span style="color:#3B82F6">根節點（晶批）</span>');
-        } else if (val.type === 'leaf') {
-          lines.push('<span style="color:#F59E0B">末端節點</span>');
-        } else if (val.type === 'branch') {
-          lines.push('<span style="color:#10B981">中間節點</span>');
-        }
-        if (val.cid && val.cid !== data.name) {
-          lines.push(`<span style="color:#94A3B8;font-size:11px">CID: ${val.cid}</span>`);
-        }
-        return lines.join('<br/>');
-      },
+  const tooltip = {
+    trigger: 'item',
+    triggerOn: 'mousemove',
+    formatter(params) {
+      const data = params?.data;
+      if (!data) {
+        return '';
+      }
+      const val = data.value || {};
+      const lines = [`<b>${data.name}</b>`];
+      if (val.type === 'serial') {
+        lines.push('<span style="color:#64748B">成品序列號</span>');
+      } else if (val.type === 'root') {
+        lines.push('<span style="color:#3B82F6">根節點（晶批）</span>');
+      } else if (val.type === 'leaf') {
+        lines.push('<span style="color:#F59E0B">末端節點</span>');
+      } else if (val.type === 'branch') {
+        lines.push('<span style="color:#10B981">中間節點</span>');
+      }
+      if (val.cid && val.cid !== data.name) {
+        lines.push(`<span style="color:#94A3B8;font-size:11px">CID: ${val.cid}</span>`);
+      }
+      return lines.join('<br/>');
     },
-    series: [
-      {
-        type: 'tree',
-        layout: 'orthogonal',
-        orient: 'LR',
-        expandAndCollapse: true,
-        initialTreeDepth: -1,
-        roam: 'move',
-        symbol: 'circle',
-        symbolSize: 10,
-        label: {
-          show: true,
-          position: 'right',
-          fontSize: 11,
-          color: '#334155',
-          overflow: 'truncate',
-          ellipsis: '…',
-          width: 160,
-        },
-        lineStyle: {
-          width: 1.5,
-          color: '#CBD5E1',
-          curveness: 0.5,
-        },
-        emphasis: {
-          focus: 'ancestor',
-          itemStyle: {
-            borderWidth: 2,
-          },
-          label: {
-            fontWeight: 'bold',
-          },
-        },
-        animationDuration: 350,
-        animationDurationUpdate: 300,
+  };
+
+  // Single root → one series, full area
+  if (trees.length === 1) {
+    return {
+      tooltip,
+      series: [{
+        ...TREE_SERIES_DEFAULTS,
         left: 40,
         right: 180,
         top: 20,
         bottom: 20,
-        data: echartsData.value,
-      },
-    ],
-  };
+        data: [trees[0]],
+      }],
+    };
+  }
+
+  // Multiple roots → one series per tree, each in its own vertical band
+  const leafCounts = trees.map(countLeaves);
+  const totalLeaves = leafCounts.reduce((a, b) => a + b, 0);
+  const GAP_PX = 12;
+  const totalGapPercent = ((trees.length - 1) * GAP_PX / 800) * 100;
+  const usablePercent = 100 - totalGapPercent;
+
+  let cursor = 0;
+  const series = trees.map((tree, index) => {
+    const fraction = leafCounts[index] / totalLeaves;
+    const heightPercent = Math.max(10, usablePercent * fraction);
+    const topPercent = cursor;
+    cursor += heightPercent + (GAP_PX / 800) * 100;
+
+    return {
+      ...TREE_SERIES_DEFAULTS,
+      left: 40,
+      right: 180,
+      top: `${topPercent}%`,
+      height: `${heightPercent}%`,
+      data: [tree],
+    };
+  });
+
+  return { tooltip, series };
 });
 
 function handleNodeClick(params) {
diff --git a/frontend/src/query-tool/components/LotTimeline.vue b/frontend/src/query-tool/components/LotTimeline.vue
index b406f2d..61218c7 100644
--- a/frontend/src/query-tool/components/LotTimeline.vue
+++ b/frontend/src/query-tool/components/LotTimeline.vue
@@ -24,16 +24,18 @@ function safeDate(value) {
   return parsed ? parsed : null;
 }
 
-function fallbackTrackId() {
-  const first = props.historyRows[0];
-  return normalizeText(first?.WORKCENTERNAME) || 'UNKNOWN_TRACK';
-}
-
+// ── Tracks: group by (WORKCENTER_GROUP × LOT ID × Equipment) ──
 const tracks = computed(() => {
   const grouped = new Map();
 
   props.historyRows.forEach((row, index) => {
-    const workcenterName = normalizeText(row?.WORKCENTERNAME) || `WORKCENTER-${index + 1}`;
+    const groupName = normalizeText(row?.WORKCENTER_GROUP)
+      || normalizeText(row?.WORKCENTERNAME)
+      || `WORKCENTER-${index + 1}`;
+    const lotId = normalizeText(row?.CONTAINERNAME || row?.CONTAINERID) || '';
+    const equipment = normalizeText(row?.EQUIPMENTNAME) || '';
+    const trackKey = `${groupName}||${lotId}||${equipment}`;
+
     const start = safeDate(row?.TRACKINTIMESTAMP);
     const end = safeDate(row?.TRACKOUTTIMESTAMP) || (start ? new Date(start.getTime() + (1000 * 60 * 30)) : null);
 
@@ -41,26 +43,30 @@ const tracks = computed(() => {
       return;
     }
 
-    if (!grouped.has(workcenterName)) {
-      grouped.set(workcenterName, []);
+    if (!grouped.has(trackKey)) {
+      grouped.set(trackKey, { groupName, lotId, equipment, bars: [] });
     }
 
-    grouped.get(workcenterName).push({
-      id: `${workcenterName}-${index}`,
+    grouped.get(trackKey).bars.push({
+      id: `${trackKey}-${index}`,
       start,
       end,
-      type: workcenterName,
-      label: row?.SPECNAME || workcenterName,
-      detail: `${normalizeText(row?.CONTAINERNAME || row?.CONTAINERID)} | ${normalizeText(row?.EQUIPMENTNAME)}`,
+      type: groupName,
+      label: row?.SPECNAME || groupName,
     });
   });
 
-  return [...grouped.entries()].map(([trackId, bars]) => ({
-    id: trackId,
-    label: trackId,
+  return [...grouped.entries()].map(([trackKey, { groupName, lotId, equipment, bars }]) => ({
+    id: trackKey,
+    group: groupName,
+    label: groupName,
+    sublabels: [
+      lotId ? `LOT ID: ${lotId}` : '',
+      equipment ? `機台編號: ${equipment}` : '',
+    ].filter(Boolean),
     layers: [
       {
-        id: `${trackId}-lots`,
+        id: `${trackKey}-lots`,
         bars,
         opacity: 0.85,
       },
@@ -68,6 +74,22 @@ const tracks = computed(() => {
   }));
 });
 
+// ── Events: resolve trackId to compound key via group matching ──
+const groupToFirstTrackId = computed(() => {
+  const map = new Map();
+  tracks.value.forEach((track) => {
+    if (!map.has(track.group)) {
+      map.set(track.group, track.id);
+    }
+  });
+  return map;
+});
+
+function resolveEventTrackId(row) {
+  const group = normalizeText(row?.WORKCENTER_GROUP) || normalizeText(row?.WORKCENTERNAME) || '';
+  return groupToFirstTrackId.value.get(group) || group;
+}
+
 const events = computed(() => {
   const markers = [];
 
@@ -79,7 +101,7 @@ const events = computed(() => {
 
     markers.push({
       id: `hold-${index}`,
-      trackId: normalizeText(row?.WORKCENTERNAME) || fallbackTrackId(),
+      trackId: resolveEventTrackId(row),
       time,
       type: 'HOLD',
       shape: 'diamond',
@@ -96,7 +118,7 @@ const events = computed(() => {
 
     markers.push({
       id: `material-${index}`,
-      trackId: normalizeText(row?.WORKCENTERNAME) || fallbackTrackId(),
+      trackId: resolveEventTrackId(row),
       time,
       type: 'MATERIAL',
       shape: 'triangle',
@@ -114,14 +136,22 @@ const colorMap = computed(() => {
     MATERIAL: '#0ea5e9',
   };
 
+  // Color by workcenter group (not compound key) so same group = same color
+  const seen = new Set();
   tracks.value.forEach((track) => {
-    colors[track.id] = hashColor(track.id);
+    if (!seen.has(track.group)) {
+      seen.add(track.group);
+      colors[track.group] = hashColor(track.group);
+    }
   });
 
   return colors;
 });
 
 const timeRange = computed(() => {
+  // Derive range ONLY from history bars so it updates when LOT selection
+  // or workcenter group filter changes. Hold/material events are supplementary
+  // markers and should not stretch the visible range.
   const timestamps = [];
 
   tracks.value.forEach((track) => {
@@ -133,10 +163,6 @@ const timeRange = computed(() => {
     });
   });
 
-  events.value.forEach((eventItem) => {
-    timestamps.push(eventItem.time?.getTime?.() || 0);
-  });
-
   const normalized = timestamps.filter((item) => Number.isFinite(item) && item > 0);
   if (normalized.length === 0) {
     return null;
@@ -163,15 +189,15 @@ const timeRange = computed(() => {
       歷程資料不足，無法產生 Timeline
     </div>
 
-    <div v-else class="max-h-[420px] overflow-y-auto rounded-card border border-stroke-soft">
+    <div v-else class="max-h-[520px] overflow-y-auto">
       <TimelineChart
         :tracks="tracks"
         :events="events"
         :time-range="timeRange"
         :color-map="colorMap"
-        :label-width="180"
-        :track-row-height="46"
-        :min-chart-width="1040"
+        :label-width="200"
+        :track-row-height="58"
+        :min-chart-width="600"
       />
     </div>
   </section>
diff --git a/frontend/src/shared-ui/components/TimelineChart.vue b/frontend/src/shared-ui/components/TimelineChart.vue
index 205d04f..275902e 100644
--- a/frontend/src/shared-ui/components/TimelineChart.vue
+++ b/frontend/src/shared-ui/components/TimelineChart.vue
@@ -1,5 +1,5 @@
 <script setup>
-import { computed, ref } from 'vue';
+import { computed, onBeforeUnmount, onMounted, ref } from 'vue';
 
 import { formatDateTime, normalizeText, parseDateTime } from '../../query-tool/utils/values.js';
 
@@ -30,11 +30,13 @@ const props = defineProps({
   },
   minChartWidth: {
     type: Number,
-    default: 960,
+    default: 600,
   },
 });
 
-const AXIS_HEIGHT = 42;
+const AXIS_HEIGHT = 32;
+const RANGE_PAD_RATIO = 0.03;
+
 const tooltipRef = ref({
   visible: false,
   x: 0,
@@ -43,6 +45,7 @@ const tooltipRef = ref({
   lines: [],
 });
 const containerRef = ref(null);
+const scrollRef = ref(null);
 
 function toTimestamp(value) {
   if (typeof value === 'number') {
@@ -80,34 +83,35 @@ const normalizedTimeRange = computed(() => {
   const explicitStart = toTimestamp(props.timeRange?.start);
   const explicitEnd = toTimestamp(props.timeRange?.end);
 
+  let startMs;
+  let endMs;
+
   if (explicitStart !== null && explicitEnd !== null && explicitEnd > explicitStart) {
-    return {
-      startMs: explicitStart,
-      endMs: explicitEnd,
-    };
-  }
-
-  const timestamps = collectDomainTimestamps();
-  if (timestamps.length === 0) {
-    const now = Date.now();
-    return {
-      startMs: now - (1000 * 60 * 60),
-      endMs: now + (1000 * 60 * 60),
-    };
-  }
-
-  const startMs = Math.min(...timestamps);
-  const endMs = Math.max(...timestamps);
-  if (endMs === startMs) {
-    return {
-      startMs,
-      endMs: startMs + (1000 * 60 * 60),
-    };
+    startMs = explicitStart;
+    endMs = explicitEnd;
+  } else {
+    const timestamps = collectDomainTimestamps();
+    if (timestamps.length === 0) {
+      const now = Date.now();
+      return {
+        startMs: now - (1000 * 60 * 60),
+        endMs: now + (1000 * 60 * 60),
+      };
+    }
+
+    startMs = Math.min(...timestamps);
+    endMs = Math.max(...timestamps);
+    if (endMs === startMs) {
+      endMs = startMs + (1000 * 60 * 60);
+    }
   }
 
+  // Add a small padding so bars don't sit at the very edge
+  const span = endMs - startMs;
+  const pad = span * RANGE_PAD_RATIO;
   return {
-    startMs,
-    endMs,
+    startMs: startMs - pad,
+    endMs: endMs + pad,
   };
 });
 
@@ -119,8 +123,16 @@ const trackCount = computed(() => props.tracks.length);
 
 const chartWidth = computed(() => {
   const hours = totalDurationMs.value / (1000 * 60 * 60);
-  const estimated = Math.round(hours * 36);
-  return Math.max(props.minChartWidth, estimated);
+  // Adaptive scaling: longer durations get fewer px/hour to stay compact
+  let pxPerHour;
+  if (hours <= 6) pxPerHour = 120;
+  else if (hours <= 24) pxPerHour = 60;
+  else if (hours <= 72) pxPerHour = 30;
+  else if (hours <= 168) pxPerHour = 16;
+  else if (hours <= 720) pxPerHour = 6;
+  else pxPerHour = 3;
+
+  return Math.max(props.minChartWidth, Math.round(hours * pxPerHour));
 });
 
 const svgHeight = computed(() => AXIS_HEIGHT + trackCount.value * props.trackRowHeight + 2);
@@ -159,37 +171,45 @@ function normalizeEvent(event) {
   };
 }
 
+const HOUR_MS = 1000 * 60 * 60;
+const DAY_MS = HOUR_MS * 24;
+
 const timelineTicks = computed(() => {
   const ticks = [];
   const rangeMs = totalDurationMs.value;
-  const rangeHours = rangeMs / (1000 * 60 * 60);
+  const rangeHours = rangeMs / HOUR_MS;
 
-  const stepMs = rangeHours <= 48
-    ? (1000 * 60 * 60)
-    : (1000 * 60 * 60 * 24);
+  let stepMs;
+  if (rangeHours <= 12) stepMs = HOUR_MS;
+  else if (rangeHours <= 48) stepMs = HOUR_MS * 2;
+  else if (rangeHours <= 168) stepMs = HOUR_MS * 6;
+  else if (rangeHours <= 720) stepMs = DAY_MS;
+  else stepMs = DAY_MS * 3;
 
   const start = normalizedTimeRange.value.startMs;
   const end = normalizedTimeRange.value.endMs;
 
-  let cursor = start;
+  // Snap cursor to the nearest clean boundary
+  const snapMs = stepMs >= DAY_MS ? DAY_MS : HOUR_MS;
+  let cursor = Math.ceil(start / snapMs) * snapMs;
+
   while (cursor <= end) {
     const date = new Date(cursor);
-    const label = stepMs < (1000 * 60 * 60 * 24)
-      ? `${String(date.getHours()).padStart(2, '0')}:00`
-      : `${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')}`;
-
-    ticks.push({
-      timeMs: cursor,
-      label,
-    });
+    let label;
+    if (stepMs < DAY_MS) {
+      label = `${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')} ${String(date.getHours()).padStart(2, '0')}:00`;
+    } else {
+      label = `${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')}`;
+    }
 
+    ticks.push({ timeMs: cursor, label });
     cursor += stepMs;
   }
 
   if (ticks.length < 2) {
     ticks.push({
       timeMs: end,
-      label: stepMs < (1000 * 60 * 60 * 24) ? 'End' : '結束',
+      label: '結束',
     });
   }
 
@@ -254,17 +274,26 @@ const legendItems = computed(() => {
   }));
 });
 
+// ── Tooltip (fixed-position, teleported to body) ──────────────
+const TOOLTIP_MAX_W = 288; // max-w-72
+const TOOLTIP_EST_H = 120;
+
 function showTooltip(event, title, lines = []) {
-  const host = containerRef.value;
-  if (!host) {
-    return;
+  let x = event.clientX + 14;
+  let y = event.clientY + 14;
+
+  // Flip when near viewport edges
+  if (x + TOOLTIP_MAX_W > window.innerWidth - 8) {
+    x = event.clientX - TOOLTIP_MAX_W - 8;
+  }
+  if (y + TOOLTIP_EST_H > window.innerHeight - 8) {
+    y = event.clientY - TOOLTIP_EST_H - 8;
   }
 
-  const bounds = host.getBoundingClientRect();
   tooltipRef.value = {
     visible: true,
-    x: event.clientX - bounds.left + 12,
-    y: event.clientY - bounds.top + 12,
+    x: Math.max(4, x),
+    y: Math.max(4, y),
     title,
     lines,
   };
@@ -274,6 +303,21 @@ function hideTooltip() {
   tooltipRef.value.visible = false;
 }
 
+// Hide tooltip when the chart area scrolls (fixed tooltip would become stale)
+function handleScroll() {
+  if (tooltipRef.value.visible) {
+    hideTooltip();
+  }
+}
+
+onMounted(() => {
+  scrollRef.value?.addEventListener('scroll', handleScroll, { passive: true });
+});
+onBeforeUnmount(() => {
+  scrollRef.value?.removeEventListener('scroll', handleScroll);
+  hideTooltip();
+});
+
 function handleBarHover(mouseEvent, bar, trackLabel) {
   const normalized = normalizeBar(bar);
   if (!normalized) {
@@ -282,7 +326,7 @@ function handleBarHover(mouseEvent, bar, trackLabel) {
 
   const start = formatDateTime(normalized.start);
   const end = formatDateTime(normalized.end);
-  const durationHours = ((normalized.endMs - normalized.startMs) / (1000 * 60 * 60)).toFixed(2);
+  const durationHours = ((normalized.endMs - normalized.startMs) / HOUR_MS).toFixed(2);
 
   const title = normalizeText(normalized.label) || normalizeText(normalized.type) || '區段';
   const lines = [
@@ -325,7 +369,7 @@ function eventPath(type, x, y) {
 
 <template>
   <div class="rounded-card border border-stroke-soft bg-white p-3">
-    <div class="mb-3 flex flex-wrap items-center gap-3 text-xs text-slate-600">
+    <div class="mb-2 flex flex-wrap items-center gap-3 text-xs text-slate-600">
       <span class="font-medium text-slate-700">Timeline</span>
       <div v-for="item in legendItems" :key="item.key" class="flex items-center gap-1">
         <span class="inline-block size-2 rounded-full" :style="{ backgroundColor: item.color }" />
@@ -335,26 +379,40 @@ function eventPath(type, x, y) {
 
     <div
       ref="containerRef"
-      class="relative overflow-hidden rounded-card border border-stroke-soft bg-surface-muted/30"
+      class="relative rounded-card border border-stroke-soft bg-surface-muted/30"
       @mouseleave="hideTooltip"
     >
       <div class="grid" :style="{ gridTemplateColumns: `${labelWidth}px minmax(0, 1fr)` }">
+        <!-- Track labels (sticky left) -->
         <div class="sticky left-0 z-20 border-r border-stroke-soft bg-white">
-          <div class="flex h-[42px] items-center border-b border-stroke-soft px-3 text-xs font-semibold tracking-wide text-slate-500">
+          <div
+            class="flex items-center border-b border-stroke-soft px-3 text-[10px] font-semibold uppercase tracking-wider text-slate-400"
+            :style="{ height: `${AXIS_HEIGHT}px` }"
+          >
             Track
           </div>
 
           <div
             v-for="track in tracks"
             :key="track.id || track.label"
-            class="flex items-center border-b border-stroke-soft/70 px-3 text-xs text-slate-700"
+            class="flex flex-col justify-center border-b border-stroke-soft/70 px-3"
             :style="{ height: `${trackRowHeight}px` }"
           >
-            <span class="line-clamp-1">{{ track.label }}</span>
+            <span class="truncate text-xs font-medium text-slate-700">{{ track.label }}</span>
+            <!-- sublabels (array) takes priority over sublabel (string) -->
+            <template v-if="track.sublabels?.length">
+              <span
+                v-for="sub in track.sublabels"
+                :key="sub"
+                class="truncate text-[10px] leading-tight text-slate-400"
+              >{{ sub }}</span>
+            </template>
+            <span v-else-if="track.sublabel" class="truncate text-[10px] leading-tight text-slate-400">{{ track.sublabel }}</span>
           </div>
         </div>
 
-        <div class="overflow-x-auto">
+        <!-- Chart area (scrollable) -->
+        <div ref="scrollRef" class="overflow-x-auto">
           <svg
             :width="chartWidth"
             :height="svgHeight"
@@ -363,8 +421,9 @@ function eventPath(type, x, y) {
           >
             <rect x="0" y="0" :width="chartWidth" :height="svgHeight" fill="#ffffff" />
 
+            <!-- Time axis -->
             <g>
-              <line x1="0" :x2="chartWidth" y1="41" y2="41" stroke="#cbd5e1" stroke-width="1" />
+              <line x1="0" :x2="chartWidth" :y1="AXIS_HEIGHT - 1" :y2="AXIS_HEIGHT - 1" stroke="#cbd5e1" stroke-width="1" />
               <g v-for="tick in timelineTicks" :key="tick.timeMs">
                 <line
                   :x1="xByTimestamp(tick.timeMs)"
@@ -376,16 +435,18 @@ function eventPath(type, x, y) {
                   stroke-dasharray="2 3"
                 />
                 <text
-                  :x="xByTimestamp(tick.timeMs) + 2"
-                  y="14"
+                  :x="xByTimestamp(tick.timeMs) + 3"
+                  y="13"
                   fill="#475569"
-                  font-size="11"
+                  font-size="10"
+                  font-family="ui-monospace, monospace"
                 >
                   {{ tick.label }}
                 </text>
               </g>
             </g>
 
+            <!-- Track rows -->
             <g v-for="(track, trackIndex) in tracks" :key="track.id || track.label">
               <rect
                 x="0"
@@ -396,6 +457,7 @@ function eventPath(type, x, y) {
                 opacity="0.45"
               />
 
+              <!-- Bars -->
               <g v-for="(layer, layerIndex) in (track.layers || [])" :key="layer.id || layerIndex">
                 <template
                   v-for="(bar, barIndex) in (layer.bars || [])"
@@ -405,16 +467,18 @@ function eventPath(type, x, y) {
                     v-if="normalizeBar(bar)"
                     :x="xByTimestamp(normalizeBar(bar).startMs)"
                     :y="layerGeometry(trackIndex, layerIndex, (track.layers || []).length).y"
-                    :width="Math.max(2, xByTimestamp(normalizeBar(bar).endMs) - xByTimestamp(normalizeBar(bar).startMs))"
+                    :width="Math.max(4, xByTimestamp(normalizeBar(bar).endMs) - xByTimestamp(normalizeBar(bar).startMs))"
                     :height="layerGeometry(trackIndex, layerIndex, (track.layers || []).length).height"
                     :fill="bar.color || resolveColor(bar.type)"
                     :opacity="layer.opacity ?? (layerIndex === 0 ? 0.45 : 0.9)"
                     rx="3"
+                    class="cursor-pointer"
                     @mousemove="handleBarHover($event, bar, track.label)"
                   />
                 </template>
               </g>
 
+              <!-- Event markers -->
               <template v-for="(eventItem, eventIndex) in events" :key="eventItem.id || `${trackIndex}-event-${eventIndex}`">
                 <path
                   v-if="normalizeEvent(eventItem) && normalizeText(eventItem.trackId) === normalizeText(track.id)"
@@ -422,6 +486,7 @@ function eventPath(type, x, y) {
                   :fill="eventItem.color || resolveColor(eventItem.type)"
                   stroke="#0f172a"
                   stroke-width="0.5"
+                  class="cursor-pointer"
                   @mousemove="handleEventHover($event, eventItem, track.label)"
                 />
               </template>
@@ -429,15 +494,27 @@ function eventPath(type, x, y) {
           </svg>
         </div>
       </div>
-
-      <div
-        v-if="tooltipRef.visible"
-        class="pointer-events-none absolute z-30 max-w-72 rounded-card border border-stroke-soft bg-slate-900/95 px-2 py-1.5 text-[11px] text-slate-100 shadow-lg"
-        :style="{ left: `${tooltipRef.x}px`, top: `${tooltipRef.y}px` }"
-      >
-        <p class="font-semibold text-white">{{ tooltipRef.title }}</p>
-        <p v-for="line in tooltipRef.lines" :key="line" class="mt-0.5 text-slate-200">{{ line }}</p>
-      </div>
     </div>
+
+    <!-- Tooltip: teleported to body so it's never clipped by overflow -->
+    <Teleport to="body">
+      <Transition name="tooltip-fade">
+        <div
+          v-if="tooltipRef.visible"
+          class="pointer-events-none fixed z-[9999] max-w-72 rounded-lg border border-slate-600/30 bg-slate-900/95 px-2.5 py-2 text-[11px] leading-relaxed text-slate-100 shadow-xl backdrop-blur-sm"
+          :style="{ left: `${tooltipRef.x}px`, top: `${tooltipRef.y}px` }"
+        >
+          <p class="font-semibold text-white">{{ tooltipRef.title }}</p>
+          <p v-for="line in tooltipRef.lines" :key="line" class="mt-0.5 text-slate-300">{{ line }}</p>
+        </div>
+      </Transition>
+    </Teleport>
   </div>
 </template>
+
+<style scoped>
+.tooltip-fade-enter-active { transition: opacity 0.12s ease-out; }
+.tooltip-fade-leave-active { transition: opacity 0.08s ease-in; }
+.tooltip-fade-enter-from,
+.tooltip-fade-leave-to { opacity: 0; }
+</style>
diff --git a/src/mes_dashboard/services/query_tool_service.py b/src/mes_dashboard/services/query_tool_service.py
index 06f14c5..c8ebfb0 100644
--- a/src/mes_dashboard/services/query_tool_service.py
+++ b/src/mes_dashboard/services/query_tool_service.py
@@ -381,6 +381,22 @@ def _get_workcenters_for_groups(groups: List[str]) -> List[str]:
     return get_workcenters_for_groups(groups)
 
 
+def _enrich_workcenter_group(rows: list) -> list:
+    """Add WORKCENTER_GROUP field to each history row based on WORKCENTERNAME.
+
+    Uses filter_cache workcenter mapping to resolve the group name.
+    """
+    from mes_dashboard.services.filter_cache import get_workcenter_mapping
+    mapping = get_workcenter_mapping() or {}
+    for row in rows:
+        wc_name = row.get('WORKCENTERNAME')
+        if wc_name and wc_name in mapping:
+            row['WORKCENTER_GROUP'] = mapping[wc_name].get('group', wc_name)
+        else:
+            row['WORKCENTER_GROUP'] = wc_name or ''
+    return rows
+
+
 def get_lot_history(
     container_id: str,
     workcenter_groups: Optional[List[str]] = None
@@ -415,6 +431,7 @@ def get_lot_history(
                     f"({len(workcenters)} workcenters)"
                 )
 
+        _enrich_workcenter_group(rows)
         data = _df_to_records(pd.DataFrame(rows))
 
         logger.debug(f"LOT history: {len(data)} records for {container_id}")
@@ -520,6 +537,7 @@ def get_lot_history_batch(
                     if row.get('WORKCENTERNAME') in workcenter_set
                 ]
 
+        _enrich_workcenter_group(rows)
         data = _df_to_records(pd.DataFrame(rows))
 
         logger.debug(