diff --git a/src/renderer/src/components/status-bar/StatusBar.tsx b/src/renderer/src/components/status-bar/StatusBar.tsx
index 4b15511ec7a..ebd9c3fd00e 100644
--- a/src/renderer/src/components/status-bar/StatusBar.tsx
+++ b/src/renderer/src/components/status-bar/StatusBar.tsx
@@ -55,6 +55,7 @@ import {
 } from './tooltip'
 import { ClaudeIcon, GeminiIcon, OpenAIIcon, OpenCodeGoIcon } from './icons'
 import { AgentIcon } from '@/lib/agent-catalog'
+import { formatResetDuration } from '@/lib/reset-countdown'
 import { formatWindowLabel } from '@/lib/window-label-formatter'
 import { markLiveCodexSessionsForRestart } from '@/lib/codex-session-restart'
 import { UpdateStatusSegment } from './UpdateStatusSegment'
@@ -1024,6 +1025,17 @@ function WindowLabel({ w, label }: { w: RateLimitWindow; label: string }): React
   )
 }
 
+// Why: rate-limit data only refetches every ~15min, so a reset countdown
+// computed once would freeze; tick locally to keep the collapsed badge current.
+function useNow(intervalMs: number): number {
+  const [now, setNow] = useState(() => Date.now())
+  useEffect(() => {
+    const id = window.setInterval(() => setNow(Date.now()), intervalMs)
+    return () => window.clearInterval(id)
+  }, [intervalMs])
+  return now
+}
+
 // ---------------------------------------------------------------------------
 // Provider segment
 // ---------------------------------------------------------------------------
@@ -1041,6 +1053,15 @@ function ProviderSegment({
 }): React.JSX.Element {
   const provider = p?.provider ?? 'claude'
   const statusLabel = p ? getProviderUsageStatusLabel(p) : ''
+  const now = useNow(30_000)
+
+  // Why: show the live time-until-reset for the session window instead of the
+  // fixed window length (issue #5399) so users see it without opening the panel.
+  const sessionLabel = p?.session
+    ? p.session.resetsAt != null
+      ? formatResetDuration(p.session.resetsAt - now)
+      : formatWindowLabel(p.session.windowMinutes)
+    : ''
 
   // Idle / initial load
   if (!p || p.status === 'idle') {
@@ -1102,7 +1123,7 @@ function ProviderSegment({
           )
         })}
         {visibleBuckets.length === 0 && p.session && (
-          <WindowLabel w={p.session} label={formatWindowLabel(p.session.windowMinutes)} />
+          <WindowLabel w={p.session} label={sessionLabel} />
         )}
         {isStale && <AlertTriangle size={11} className="text-muted-foreground/80" />}
       </span>
@@ -1113,9 +1134,7 @@ function ProviderSegment({
     <span className="inline-flex items-center gap-1.5">
       <ProviderIcon provider={provider} />
       {p.session && !compact && <MiniBar leftPct={Math.max(0, 100 - p.session.usedPercent)} />}
-      {p.session && (
-        <WindowLabel w={p.session} label={formatWindowLabel(p.session.windowMinutes)} />
-      )}
+      {p.session && <WindowLabel w={p.session} label={sessionLabel} />}
       {p.session && p.weekly && <span className="text-muted-foreground">·</span>}
       {p.weekly && <WindowLabel w={p.weekly} label={formatWindowLabel(p.weekly.windowMinutes)} />}
       {isStale && <AlertTriangle size={11} className="text-muted-foreground/80" />}
diff --git a/src/renderer/src/components/status-bar/tooltip.tsx b/src/renderer/src/components/status-bar/tooltip.tsx
index 44b3e0d432a..b22a89a8d92 100644
--- a/src/renderer/src/components/status-bar/tooltip.tsx
+++ b/src/renderer/src/components/status-bar/tooltip.tsx
@@ -2,12 +2,14 @@ import type { ProviderRateLimits, RateLimitWindow } from '../../../../shared/rat
 import { AgentIcon } from '@/lib/agent-catalog'
 import { ClaudeIcon, GeminiIcon, OpenAIIcon, OpenCodeGoIcon } from './icons'
 import { translate } from '@/i18n/i18n'
+import { formatResetCountdown, formatResetDuration } from '@/lib/reset-countdown'
 import {
   getProviderDisplayName,
   getProviderUsageErrorMessage,
   getProviderUsageStatusLabel
 } from './usage-error-copy'
 
+export { formatResetCountdown } from '@/lib/reset-countdown'
 export {
   getProviderDisplayName,
   getProviderUsageErrorMessage,
@@ -31,29 +33,6 @@ export function formatTimeAgo(ts: number): string {
   return `${hours}h ago`
 }
 
-function formatDuration(ms: number): string {
-  if (ms <= 0) {
-    return 'now'
-  }
-  const totalMins = Math.floor(ms / 60_000)
-  if (totalMins < 60) {
-    return `${totalMins}m`
-  }
-  const hours = Math.floor(totalMins / 60)
-  const mins = totalMins % 60
-  if (hours >= 24) {
-    const days = Math.floor(hours / 24)
-    const remHours = hours % 24
-    return remHours > 0 ? `${days}d ${remHours}h` : `${days}d`
-  }
-  return mins > 0 ? `${hours}h ${mins}m` : `${hours}h`
-}
-
-export function formatResetCountdown(ms: number): string {
-  const duration = formatDuration(ms)
-  return duration === 'now' ? 'Resets now' : `Resets in ${duration}`
-}
-
 export function formatResetCreditExpiry(
   expiresAt: number | null | undefined,
   count: number
@@ -61,7 +40,7 @@ export function formatResetCreditExpiry(
   if (!expiresAt) {
     return null
   }
-  const duration = formatDuration(expiresAt - Date.now())
+  const duration = formatResetDuration(expiresAt - Date.now())
   if (duration === 'now') {
     return count > 1
       ? translate('auto.components.status.bar.tooltip.7ec6e030a0', 'Next expires now')
diff --git a/src/renderer/src/lib/reset-countdown.test.ts b/src/renderer/src/lib/reset-countdown.test.ts
new file mode 100644
index 00000000000..61fab55a87f
--- /dev/null
+++ b/src/renderer/src/lib/reset-countdown.test.ts
@@ -0,0 +1,59 @@
+import { describe, expect, it } from 'vitest'
+import { formatResetCountdown, formatResetDuration } from './reset-countdown'
+
+const HOUR = 60 * 60_000
+const MINUTE = 60_000
+
+describe('formatResetDuration', () => {
+  it('returns "now" for zero or negative durations', () => {
+    expect(formatResetDuration(0)).toBe('now')
+    expect(formatResetDuration(-1)).toBe('now')
+  })
+
+  it('returns "<1m" for sub-minute positive durations, not "0m"', () => {
+    // Why: the 30s tick makes the final minute before reset reachable; "0m"
+    // would read as already-reset.
+    expect(formatResetDuration(1)).toBe('<1m')
+    expect(formatResetDuration(30_000)).toBe('<1m')
+    expect(formatResetDuration(59_999)).toBe('<1m')
+  })
+
+  it('returns whole minutes under an hour', () => {
+    expect(formatResetDuration(45 * MINUTE)).toBe('45m')
+    expect(formatResetDuration(MINUTE)).toBe('1m')
+  })
+
+  it('floors partial minutes', () => {
+    expect(formatResetDuration(90_000)).toBe('1m')
+  })
+
+  it('shows hours and minutes — the issue #5399 session case', () => {
+    // Session window with 3h 31m left should read "3h 31m", not a fixed "5h".
+    expect(formatResetDuration(3 * HOUR + 31 * MINUTE)).toBe('3h 31m')
+    expect(formatResetDuration(HOUR + 20 * MINUTE)).toBe('1h 20m')
+  })
+
+  it('omits minutes on a whole hour', () => {
+    expect(formatResetDuration(5 * HOUR)).toBe('5h')
+  })
+
+  it('shows days and hours past 24h (weekly windows)', () => {
+    expect(formatResetDuration(2 * 24 * HOUR + 4 * HOUR)).toBe('2d 4h')
+    expect(formatResetDuration(3 * 24 * HOUR)).toBe('3d')
+  })
+})
+
+describe('formatResetCountdown', () => {
+  it('prefixes "Resets in" for positive durations', () => {
+    expect(formatResetCountdown(3 * HOUR + 31 * MINUTE)).toBe('Resets in 3h 31m')
+  })
+
+  it('reads "Resets in <1m" in the final minute', () => {
+    expect(formatResetCountdown(30_000)).toBe('Resets in <1m')
+  })
+
+  it('reads "Resets now" once elapsed', () => {
+    expect(formatResetCountdown(0)).toBe('Resets now')
+    expect(formatResetCountdown(-1)).toBe('Resets now')
+  })
+})
diff --git a/src/renderer/src/lib/reset-countdown.ts b/src/renderer/src/lib/reset-countdown.ts
new file mode 100644
index 00000000000..86784a90018
--- /dev/null
+++ b/src/renderer/src/lib/reset-countdown.ts
@@ -0,0 +1,34 @@
+/**
+ * Formats the time remaining until a usage window resets.
+ *
+ * Shared by the expanded usage popover and the collapsed status-bar badge so
+ * both render the same live countdown (e.g. "3h 31m", "45m", "2d 4h") instead
+ * of a fixed window-length label.
+ */
+export function formatResetDuration(ms: number): string {
+  if (ms <= 0) {
+    return 'now'
+  }
+  const totalMins = Math.floor(ms / 60_000)
+  // Why: sub-minute durations floor to 0, and "0m" reads as already-reset; show
+  // "<1m" so the final minute before reset stays distinct from "now" (ms <= 0).
+  if (totalMins === 0) {
+    return '<1m'
+  }
+  if (totalMins < 60) {
+    return `${totalMins}m`
+  }
+  const hours = Math.floor(totalMins / 60)
+  const mins = totalMins % 60
+  if (hours >= 24) {
+    const days = Math.floor(hours / 24)
+    const remHours = hours % 24
+    return remHours > 0 ? `${days}d ${remHours}h` : `${days}d`
+  }
+  return mins > 0 ? `${hours}h ${mins}m` : `${hours}h`
+}
+
+export function formatResetCountdown(ms: number): string {
+  const duration = formatResetDuration(ms)
+  return duration === 'now' ? 'Resets now' : `Resets in ${duration}`
+}