diff --git a/src/renderer/src/components/stats/ClaudeUsageDailyChart.tsx b/src/renderer/src/components/stats/ClaudeUsageDailyChart.tsx
index ed6f40d22f8..3f99f7e435f 100644
--- a/src/renderer/src/components/stats/ClaudeUsageDailyChart.tsx
+++ b/src/renderer/src/components/stats/ClaudeUsageDailyChart.tsx
@@ -11,18 +11,26 @@ function formatTokens(value: number): string {
   return value.toLocaleString()
 }
 
+function getDailyTotal(entry: ClaudeUsageDailyPoint): number {
+  return entry.inputTokens + entry.outputTokens + entry.cacheReadTokens + entry.cacheWriteTokens
+}
+
+function getMaxDailyTotal(daily: ClaudeUsageDailyPoint[]): number {
+  let max = 1
+  // Why: all-time usage histories can exceed V8's argument limit if spread
+  // into Math.max, even though the chart only renders the last 10 days.
+  for (const entry of daily) {
+    max = Math.max(max, getDailyTotal(entry))
+  }
+  return max
+}
+
 type ClaudeUsageDailyChartProps = {
   daily: ClaudeUsageDailyPoint[]
 }
 
 export function ClaudeUsageDailyChart({ daily }: ClaudeUsageDailyChartProps): React.JSX.Element {
-  const maxDailyTotal = Math.max(
-    1,
-    ...daily.map(
-      (entry) =>
-        entry.inputTokens + entry.outputTokens + entry.cacheReadTokens + entry.cacheWriteTokens
-    )
-  )
+  const maxDailyTotal = getMaxDailyTotal(daily)
 
   return (
     <section className="rounded-lg border border-border/60 bg-card/40 p-4">
@@ -34,8 +42,7 @@ export function ClaudeUsageDailyChart({ daily }: ClaudeUsageDailyChartProps): Re
       </div>
       <div className="grid h-56 grid-cols-10 items-end gap-3">
         {daily.slice(-10).map((entry) => {
-          const total =
-            entry.inputTokens + entry.outputTokens + entry.cacheReadTokens + entry.cacheWriteTokens
+          const total = getDailyTotal(entry)
           const segments = [
             {
               key: 'cache-write',
diff --git a/src/renderer/src/components/stats/CodexUsageDailyChart.tsx b/src/renderer/src/components/stats/CodexUsageDailyChart.tsx
index ca5bcb9296c..88f3613047d 100644
--- a/src/renderer/src/components/stats/CodexUsageDailyChart.tsx
+++ b/src/renderer/src/components/stats/CodexUsageDailyChart.tsx
@@ -11,12 +11,22 @@ function formatTokens(value: number): string {
   return value.toLocaleString()
 }
 
+function getMaxDailyTotal(daily: CodexUsageDailyPoint[]): number {
+  let max = 1
+  // Why: all-time usage histories can exceed V8's argument limit if spread
+  // into Math.max, even though the chart only renders the last 10 days.
+  for (const entry of daily) {
+    max = Math.max(max, entry.totalTokens)
+  }
+  return max
+}
+
 type CodexUsageDailyChartProps = {
   daily: CodexUsageDailyPoint[]
 }
 
 export function CodexUsageDailyChart({ daily }: CodexUsageDailyChartProps): React.JSX.Element {
-  const maxDailyTotal = Math.max(1, ...daily.map((entry) => entry.totalTokens))
+  const maxDailyTotal = getMaxDailyTotal(daily)
 
   return (
     <section className="rounded-lg border border-border/60 bg-card/40 p-4">
diff --git a/src/renderer/src/components/stats/usage-daily-chart.test.tsx b/src/renderer/src/components/stats/usage-daily-chart.test.tsx
new file mode 100644
index 00000000000..dc6bb5e600a
--- /dev/null
+++ b/src/renderer/src/components/stats/usage-daily-chart.test.tsx
@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest'
+import type { ClaudeUsageDailyPoint } from '../../../../shared/claude-usage-types'
+import type { CodexUsageDailyPoint } from '../../../../shared/codex-usage-types'
+import { ClaudeUsageDailyChart } from './ClaudeUsageDailyChart'
+import { CodexUsageDailyChart } from './CodexUsageDailyChart'
+
+function makeDay(index: number): string {
+  return new Date(Date.UTC(2026, 0, 1 + index)).toISOString().slice(0, 10)
+}
+
+describe('usage daily charts', () => {
+  it('renders Codex/OpenCode daily charts for very large histories', () => {
+    const daily: CodexUsageDailyPoint[] = Array.from({ length: 130_000 }, (_, index) => ({
+      day: makeDay(index),
+      inputTokens: index + 1,
+      cachedInputTokens: 0,
+      outputTokens: 0,
+      reasoningOutputTokens: 0,
+      totalTokens: index + 1
+    }))
+
+    expect(() => CodexUsageDailyChart({ daily })).not.toThrow()
+  })
+
+  it('renders Claude daily charts for very large histories', () => {
+    const daily: ClaudeUsageDailyPoint[] = Array.from({ length: 130_000 }, (_, index) => ({
+      day: makeDay(index),
+      inputTokens: index + 1,
+      outputTokens: 0,
+      cacheReadTokens: 0,
+      cacheWriteTokens: 0
+    }))
+
+    expect(() => ClaudeUsageDailyChart({ daily })).not.toThrow()
+  })
+})