diff --git a/web/hwlab-cloud-web/src/components/agent/TraceTimeline.vue b/web/hwlab-cloud-web/src/components/agent/TraceTimeline.vue
index 62fb7c2a..5e593c8c 100644
--- a/web/hwlab-cloud-web/src/components/agent/TraceTimeline.vue
+++ b/web/hwlab-cloud-web/src/components/agent/TraceTimeline.vue
@@ -182,7 +182,7 @@ function firstNonEmptyString(...values: unknown[]): string | null {
       <div v-if="expanded" class="trace-disclosure-body">
         <p v-if="hiddenRowCount > 0 || inputEventWindowed" class="trace-window-notice">显示最近 {{ renderedRows.length }} 行，共 {{ eventCount }} events</p>
         <ol v-if="renderedRows.length > 0" ref="listRef" @scroll="onScroll">
-          <li v-for="(row, index) in renderedRows" :key="rowKey(row, index)" class="trace-render-row" data-testid="trace-render-row" :data-trace-id="trace.traceId || undefined" :data-event-seq="row.seq ?? undefined" :data-event-seq-authority="row.sequenceAuthority" :data-projected-seq="row.sequenceAuthority === 'projected' ? row.seq ?? undefined : undefined" :data-event-kind="row.rowId" :data-event-status="row.tone" :data-tool-state="row.toolState ?? undefined" :data-terminal="row.terminal ? 'true' : 'false'" :data-row-kind="rowIsTool(row) ? 'tool' : 'message'" :data-row-id="row.rowId" :aria-posinset="hiddenRowCount + index + 1">
+          <li v-for="(row, index) in renderedRows" :key="rowKey(row, index)" v-memo="[trace.traceId, row.rowId, row.seq, row.header, row.body, row.bodyFormat, row.tone, row.toolState, row.terminal, hiddenRowCount + index, expandedToolRowIds.has(row.rowId)]" class="trace-render-row" data-testid="trace-render-row" :data-trace-id="trace.traceId || undefined" :data-event-seq="row.seq ?? undefined" :data-event-seq-authority="row.sequenceAuthority" :data-projected-seq="row.sequenceAuthority === 'projected' ? row.seq ?? undefined : undefined" :data-event-kind="row.rowId" :data-event-status="row.tone" :data-tool-state="row.toolState ?? undefined" :data-terminal="row.terminal ? 'true' : 'false'" :data-row-kind="rowIsTool(row) ? 'tool' : 'message'" :data-row-id="row.rowId" :aria-posinset="hiddenRowCount + index + 1">
             <details v-if="rowIsTool(row)" class="trace-tool-details" :aria-busy="row.toolState === 'running' ? 'true' : undefined" @toggle="onToolDisclosureToggle(row, $event)">
               <summary :aria-label="traceToolAccessibilityLabel(row)" :title="traceToolAccessibilityLabel(row)" aria-live="polite" aria-atomic="true">
                 <code>{{ row.header }}</code>