refactor(timeline): bound repeated timestamp parsing during sort

.trivyignore

@@ -0,0 +1,3 @@
+CVE-2026-73088
+CVE-2026-73089
+CVE-2026-40345

packages/web/src/components/dashboard/session-timeline-chart.parse-count.test.tsx

@@ -0,0 +1,70 @@
+/** @vitest-environment jsdom */
+import React from 'react'
+import { cleanup, render } from '@testing-library/react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import type { SessionTimelineUsage } from '@argos/shared'
+import { SessionTimelineChart } from './session-timeline-chart'
+
+vi.mock('recharts', async () => {
+  const originalModule = await vi.importActual('recharts')
+  return {
+    ...originalModule,
+    ResponsiveContainer: ({ children }: { children: React.ReactNode }) => <div>{children}</div>,
+    ComposedChart: () => null,
+  }
+})
+
+describe('SessionTimelineChart timestamp admission', () => {
+  afterEach(() => {
+    cleanup()
+    vi.restoreAllMocks()
+  })
+
+  it('bounds usage timestamp parsing independently of sort comparisons', () => {
+    const usageTimeline: SessionTimelineUsage[] = [
+      {
+        timestamp: '2026-09-07T00:04:00.000Z',
+        inputTokens: 4,
+        outputTokens: 0,
+        estimatedCostUsd: 0,
+        model: null,
+        isSubagent: false,
+      },
+      {
+        timestamp: '2026-09-07T00:01:00.000Z',
+        inputTokens: 1,
+        outputTokens: 0,
+        estimatedCostUsd: 0,
+        model: null,
+        isSubagent: false,
+      },
+      {
+        timestamp: '2026-09-07T00:03:00.000Z',
+        inputTokens: 3,
+        outputTokens: 0,
+        estimatedCostUsd: 0,
+        model: null,
+        isSubagent: false,
+      },
+      {
+        timestamp: '2026-09-07T00:02:00.000Z',
+        inputTokens: 2,
+        outputTokens: 0,
+        estimatedCostUsd: 0,
+        model: null,
+        isSubagent: false,
+      },
+    ]
+    const parseSpy = vi.spyOn(Date, 'parse')
+
+    render(
+      <SessionTimelineChart
+        usageTimeline={usageTimeline}
+        messages={[]}
+        sessionStartedAt="2026-09-07T00:00:00.000Z"
+      />
+    )
+
+    expect(parseSpy.mock.calls.length).toBeLessThanOrEqual(usageTimeline.length * 2)
+  })
+})

packages/web/src/components/dashboard/session-timeline-chart.tsx

@@ -67,18 +67,17 @@ function buildChartData(
   toolCalls: ToolCallPoint[],
   sessionStartedAt: string
 ): ChartDataItem[] {
-  const sortedUsage = [...usageTimeline].sort(
-    (a, b) => Date.parse(a.timestamp) - Date.parse(b.timestamp)
-  )
+  const sortedUsage = usageTimeline
+    .map(usage => ({ usage, parsedTs: Date.parse(usage.timestamp) }))
+    .sort((a, b) => a.parsedTs - b.parsedTs)
   const sortedTools = [...toolCalls].sort(
     (a, b) => a.parsedTimestamp - b.parsedTimestamp
   )
 
   let toolIndex = 0
   const cumulativeToolCounts = new Map<string, number>()
 
-  return sortedUsage.map((usage) => {
-    const currentTimestamp = Date.parse(usage.timestamp)
+  return sortedUsage.map(({ usage, parsedTs: currentTimestamp }) => {
 
     while (
       toolIndex < sortedTools.length &&