diff --git a/assets/pr2950-capacity-expiry.png b/assets/pr2950-capacity-expiry.png
new file mode 100644
index 0000000000..10e3c995b9
Binary files /dev/null and b/assets/pr2950-capacity-expiry.png differ
diff --git a/gui/src/components/provider-workspace/ProviderCapacityQuota.tsx b/gui/src/components/provider-workspace/ProviderCapacityQuota.tsx
index abc2fb9e63..20907b8f6c 100644
--- a/gui/src/components/provider-workspace/ProviderCapacityQuota.tsx
+++ b/gui/src/components/provider-workspace/ProviderCapacityQuota.tsx
@@ -56,18 +56,30 @@ export function ProviderCapacityQuota({ report, pending }: { report: ProviderQuo
     ...(aggregation.customWindows ?? []).map((window, index) => ({ key: index + 3, label: window.label, window })),
   ] : [];
   const formatPercent = (value: number) => new Intl.NumberFormat(locale, { maximumFractionDigits: 1 }).format(value);
-  const formatRecoveryAt = (value: number) => new Intl.DateTimeFormat(locale, {
-    dateStyle: "medium",
-    timeStyle: "short",
-  }).format(new Date(value > 10_000_000_000 ? value : value * 1000));
+  // `Intl.DateTimeFormat.format()` throws a RangeError on a time value outside ±8.64e15 ms.
+  // These timestamps come from provider APIs and persisted cache, so one unrepresentable value
+  // would take down the whole capacity panel. Resolve to null and omit the line instead.
+  const asDate = (value: number): Date | null => {
+    const date = new Date(value > 10_000_000_000 ? value : value * 1000);
+    return Number.isFinite(date.getTime()) ? date : null;
+  };
+  const formatRecoveryAt = (value: number) => {
+    const date = asDate(value);
+    return date === null ? null : new Intl.DateTimeFormat(locale, {
+      dateStyle: "medium",
+      timeStyle: "short",
+    }).format(date);
+  };
   const localeTag = bcp47(locale);
   const formatCredits = (value: number) => new Intl.NumberFormat(localeTag, {
     style: "currency",
     currency: "USD",
   }).format(value);
-  const formatPeriodEnd = (value: number) => new Intl.DateTimeFormat(localeTag, {
-    dateStyle: "medium",
-  }).format(new Date(value > 10_000_000_000 ? value : value * 1000));
+  const formatPeriodEnd = (value: number) => {
+    const date = asDate(value);
+    return date === null ? null : new Intl.DateTimeFormat(localeTag, { dateStyle: "medium" }).format(date);
+  };
+  const periodEnd = credits?.expiresAt === undefined ? null : formatPeriodEnd(credits.expiresAt);
 
   return (
     <>
@@ -91,19 +103,20 @@ export function ProviderCapacityQuota({ report, pending }: { report: ProviderQuo
               <strong>{formatCredits(credits.remaining)}</strong>
             </div>
           )}
-          {credits?.expiresAt !== undefined && (
+          {periodEnd !== null && (
             <div className="pws-capacity-recovery">
-              <span>{t("quota.creditsPeriodEnds", { date: formatPeriodEnd(credits.expiresAt) })}</span>
+              <span>{t("quota.creditsPeriodEnds", { date: periodEnd })}</span>
             </div>
           )}
-          {recoveryRows.flatMap(({ key, label, window }) => (
-            window.nextRecoveryAt !== undefined && window.nextRecoveryPercent !== undefined
+          {recoveryRows.flatMap(({ key, label, window }) => {
+            const recoveryAt = window.nextRecoveryAt === undefined ? null : formatRecoveryAt(window.nextRecoveryAt);
+            return recoveryAt !== null && window.nextRecoveryPercent !== undefined
               ? [<div className="pws-capacity-recovery" key={key}>
-                  <span>{t("pws.capacity.nextRecovery")} · {label} · {formatRecoveryAt(window.nextRecoveryAt)}</span>
+                  <span>{t("pws.capacity.nextRecovery")} · {label} · {recoveryAt}</span>
                   <strong>{t("pws.capacity.recoveryShare", { percent: formatPercent(window.nextRecoveryPercent) })}</strong>
                 </div>]
-              : []
-          ))}
+              : [];
+          })}
           {showsAggregate && aggregation && aggregation.currentAccount?.quota && (
             <div className="pws-capacity-current">
               <span className="pws-capacity-label">
diff --git a/gui/src/provider-workspace/report.ts b/gui/src/provider-workspace/report.ts
index 539fbba2f2..4d4ff53f3b 100644
--- a/gui/src/provider-workspace/report.ts
+++ b/gui/src/provider-workspace/report.ts
@@ -39,6 +39,22 @@ const finite = (value: unknown): number | undefined => (
   typeof value === "number" && Number.isFinite(value) ? value : undefined
 );
 
+/**
+ * A finite number is not necessarily a representable date.
+ *
+ * Reports are also read from persisted cache, so a bogus expiry recorded before the wire-side
+ * guard existed still reaches the GUI. `Intl.DateTimeFormat.format()` throws a RangeError on an
+ * out-of-range time value rather than rendering it, which turns one bad provider field into a
+ * render fault for the whole capacity panel. Drop the field instead: the rest of the credit
+ * figures stay useful without it.
+ */
+const dateTimestamp = (value: unknown): number | undefined => {
+  const timestamp = finite(value);
+  if (timestamp === undefined) return undefined;
+  const milliseconds = timestamp > 10_000_000_000 ? timestamp : timestamp * 1000;
+  return Number.isFinite(new Date(milliseconds).getTime()) ? timestamp : undefined;
+};
+
 function quotaFromUnknown(quota: unknown, fallbackUpdatedAt?: number): AccountQuota | null {
   if (!quota || typeof quota !== "object" || Array.isArray(quota)) return null;
   const q = quota as Record<string, unknown>;
@@ -61,7 +77,7 @@ function quotaFromUnknown(quota: unknown, fallbackUpdatedAt?: number): AccountQu
   const creditsLimit = finite(creditsRaw?.limit);
   const creditsRemaining = finite(creditsRaw?.remaining);
   const creditsPercent = finite(creditsRaw?.percent);
-  const creditsExpiresAt = finite(creditsRaw?.expiresAt);
+  const creditsExpiresAt = dateTimestamp(creditsRaw?.expiresAt);
   const creditsUsd = creditsUsed !== undefined
     && creditsLimit !== undefined
     && creditsRemaining !== undefined
diff --git a/gui/tests/provider-capacity-credits.test.tsx b/gui/tests/provider-capacity-credits.test.tsx
index 35045aa870..38035c97c3 100644
--- a/gui/tests/provider-capacity-credits.test.tsx
+++ b/gui/tests/provider-capacity-credits.test.tsx
@@ -39,3 +39,13 @@ test("credits with an expiry render the localized billing-period end date", () =
   expect(markup).toContain("Credits balance");
   expect(markup).toContain("Billing period ends 26 Aug 2026");
 });
+
+// Rendering is the failure point, not just the value: Intl.DateTimeFormat.format() throws a
+// RangeError on a time value outside ±8.64e15 ms, so an unrepresentable expiry took down the
+// whole capacity panel rather than showing a wrong date.
+test("credits with an unrepresentable expiry still render the balance", () => {
+  const markup = renderCredits(1e20);
+  expect(markup).toContain("Credits balance");
+  expect(markup).toContain("US$37.50");
+  expect(markup).not.toContain("Billing period ends");
+});
diff --git a/gui/tests/provider-capacity.test.ts b/gui/tests/provider-capacity.test.ts
index 3916b3eadb..5911e89d61 100644
--- a/gui/tests/provider-capacity.test.ts
+++ b/gui/tests/provider-capacity.test.ts
@@ -61,6 +61,18 @@ test("provider quota reports reject malformed required credits and drop malforme
     creditsUsd: { used: 12.5, limit: 50, remaining: 37.5, percent: 25 },
     updatedAt: 123,
   });
+
+  // Persisted reports predate the wire-side guard, so normalization is a second line of
+  // defence: an unrepresentable expiry must be dropped rather than handed to a formatter.
+  expect(accountQuotaFromReport({
+    updatedAt: 123,
+    quota: {
+      creditsUsd: { used: 12.5, limit: 50, remaining: 37.5, percent: 25, expiresAt: 1e20 },
+    },
+  })).toEqual({
+    creditsUsd: { used: 12.5, limit: 50, remaining: 37.5, percent: 25 },
+    updatedAt: 123,
+  });
 });
 
 test("capacity metadata preserves estimate, raw current quota, recovery percent, and incomplete coverage", () => {
diff --git a/src/providers/quota-wire.ts b/src/providers/quota-wire.ts
index 0abcb69efe..31a0c81457 100644
--- a/src/providers/quota-wire.ts
+++ b/src/providers/quota-wire.ts
@@ -30,7 +30,12 @@ export const QUOTA_JSON_READ_FAILURE = Symbol("quota-json-read-failure");
 /** Unix 0 / negative values are sentinels, not reset clocks (Command Code fiveHour.resetAt: 0). */
 export function epochMillis(value: number): number | undefined {
   if (!Number.isFinite(value) || value <= 0) return undefined;
-  return value > 10_000_000_000 ? value : value * 1000;
+  const milliseconds = value > 10_000_000_000 ? value : value * 1000;
+  // A finite number is not necessarily a representable date. ECMAScript caps time values at
+  // ±8.64e15 ms, and `Intl.DateTimeFormat.format()` throws a RangeError past that instead of
+  // rendering something wrong. A provider that reports a bogus expiry must not become a
+  // rendering fault in every consumer that formats it.
+  return Number.isFinite(new Date(milliseconds).getTime()) ? milliseconds : undefined;
 }
 
 export function normalizeResetAt(value: unknown): number | undefined {
diff --git a/src/providers/quota.ts b/src/providers/quota.ts
index 98bd079119..e27bb29a31 100644
--- a/src/providers/quota.ts
+++ b/src/providers/quota.ts
@@ -1153,14 +1153,17 @@ export function parseXaiCreditsResponse(value: unknown): { percent: number; rese
   if (!config) return null;
   const period = asRecord(config.currentPeriod);
   if (!period || period.type !== "USAGE_PERIOD_TYPE_WEEKLY") return null;
-  const resetAt = normalizeResetAt(period.end);
-  if (resetAt === undefined) return null;
+  let percent = 0;
   if (config.creditUsagePercent !== undefined) {
-    const percent = normalizePercent(config.creditUsagePercent);
-    if (percent === undefined) return null;
-    return { percent, resetAt };
+    const normalized = normalizePercent(config.creditUsagePercent);
+    if (normalized === undefined) return null;
+    percent = normalized;
   }
-  return { percent: 0, resetAt };
+  const resetAt = normalizeResetAt(period.end);
+  return {
+    percent,
+    ...(resetAt !== undefined ? { resetAt } : {}),
+  };
 }
 
 async function fetchXaiWeeklyCredits(accessToken: string, userId: string): Promise<ProviderQuota | null> {
diff --git a/tests/command-code-quota.test.ts b/tests/command-code-quota.test.ts
index 3e8da6d0d3..8ba447baaf 100644
--- a/tests/command-code-quota.test.ts
+++ b/tests/command-code-quota.test.ts
@@ -364,6 +364,38 @@ describe("Command Code provider quota", () => {
     });
   });
 
+  // An out-of-range period end is not merely a wrong date: every consumer that formats it
+  // through Intl throws a RangeError. Drop the field and keep the usable credit figures.
+  test("an out-of-range subscription period end is dropped, not carried into the report", async () => {
+    globalThis.fetch = (async (input: RequestInfo | URL) => {
+      const url = String(input);
+      const body = url.includes("/alpha/whoami")
+        ? {}
+        : url.includes("/alpha/billing/subscriptions")
+          ? { data: { currentPeriodStart: "2026-08-01T00:00:00.000Z", currentPeriodEnd: 1e20 } }
+          : url.includes("/alpha/usage/summary")
+            ? { totalCost: 12 }
+            : {
+              credits: { monthlyCredits: 0, purchasedCredits: 0, freeCredits: 0 },
+              windowLimits: { fiveHour: { cap: 100, used: 40 } },
+            };
+      return new Response(JSON.stringify(body), { status: 200, headers: { "content-type": "application/json" } });
+    }) as typeof fetch;
+
+    const result = await fetchProviderQuotaReports(commandCodeConfig(), true);
+
+    expect(result.reports[0]?.quota).toEqual({
+      fiveHourPercent: 40,
+      creditsUsd: {
+        used: 12,
+        limit: 12,
+        remaining: 0,
+        percent: 100,
+      },
+      updatedAt: expect.any(Number),
+    });
+  });
+
   test("a mixed balance with roll-over purchased credits carries no subscription expiry", async () => {
     globalThis.fetch = (async (input: RequestInfo | URL) => {
       const url = String(input);
diff --git a/tests/provider-quota.test.ts b/tests/provider-quota.test.ts
index 6d0e395f3d..5eef964306 100644
--- a/tests/provider-quota.test.ts
+++ b/tests/provider-quota.test.ts
@@ -2393,6 +2393,12 @@ describe("fetchProviderQuotaReports", () => {
       percent: 0,
       resetAt: Date.parse("2026-08-15T13:05:52.277209Z"),
     });
+    expect(parseXaiCreditsResponse({
+      config: {
+        creditUsagePercent: 42,
+        currentPeriod: { type: "USAGE_PERIOD_TYPE_WEEKLY", end: 1e20 },
+      },
+    })).toEqual({ percent: 42 });
     expect(parseXaiCreditsResponse({
       config: {
         creditUsagePercent: 10,