fix: format extra usage in the currency reported by the usage API

src/types/RenderContext.ts

@@ -20,6 +20,7 @@ export interface RenderUsageData {
     extraUsageLimit?: number;
     extraUsageUsed?: number;
     extraUsageUtilization?: number;
+    extraUsageCurrency?: string;
     error?: 'no-credentials' | 'timeout' | 'rate-limited' | 'api-error' | 'parse-error';
 }
 

src/utils/__tests__/usage-fetch.test.ts

@@ -309,7 +309,8 @@ describe('fetchUsageData error handling', () => {
             is_enabled: true,
             monthly_limit: 400000,
             used_credits: 10600,
-            utilization: 2.6
+            utilization: 2.6,
+            currency: 'EUR'
         }
     });
     const rateLimitedResponseBody = JSON.stringify({
@@ -572,7 +573,8 @@ describe('fetchUsageData error handling', () => {
                 extraUsageEnabled: true,
                 extraUsageLimit: 400000,
                 extraUsageUsed: 10600,
-                extraUsageUtilization: 2.6
+                extraUsageUtilization: 2.6,
+                extraUsageCurrency: 'EUR'
             });
             expect(result.second).toEqual(result.first);
             expect(result.requestCount).toBe(1);

src/utils/usage-fetch.ts

@@ -53,6 +53,7 @@ const CachedUsageDataSchema = z.object({
     extraUsageLimit: z.number().nullable().optional(),
     extraUsageUsed: z.number().nullable().optional(),
     extraUsageUtilization: z.number().nullable().optional(),
+    extraUsageCurrency: z.string().nullable().optional(),
     error: z.string().nullable().optional()
 });
 
@@ -72,7 +73,8 @@ const UsageApiResponseSchema = z.looseObject({
         is_enabled: z.boolean().nullable().optional(),
         monthly_limit: z.number().nullable().optional(),
         used_credits: z.number().nullable().optional(),
-        utilization: z.number().nullable().optional()
+        utilization: z.number().nullable().optional(),
+        currency: z.string().nullable().optional()
     }).nullable().optional()
 });
 
@@ -115,6 +117,7 @@ function parseCachedUsageData(rawJson: string): UsageData | null {
         extraUsageLimit: parsed.extraUsageLimit ?? undefined,
         extraUsageUsed: parsed.extraUsageUsed ?? undefined,
         extraUsageUtilization: parsed.extraUsageUtilization ?? undefined,
+        extraUsageCurrency: parsed.extraUsageCurrency ?? undefined,
         error: parsedError.success ? parsedError.data : undefined
     };
 }
@@ -137,7 +140,8 @@ function parseUsageApiResponse(rawJson: string): UsageData | null {
         extraUsageEnabled: parsed.extra_usage?.is_enabled ?? undefined,
         extraUsageLimit: parsed.extra_usage?.monthly_limit ?? undefined,
         extraUsageUsed: parsed.extra_usage?.used_credits ?? undefined,
-        extraUsageUtilization: parsed.extra_usage?.utilization ?? undefined
+        extraUsageUtilization: parsed.extra_usage?.utilization ?? undefined,
+        extraUsageCurrency: parsed.extra_usage?.currency ?? undefined
     };
 }
 

src/utils/usage-prefetch.ts

@@ -30,7 +30,8 @@ const USAGE_DATA_FIELDS: UsageDataField[] = [
     'extraUsageEnabled',
     'extraUsageLimit',
     'extraUsageUsed',
-    'extraUsageUtilization'
+    'extraUsageUtilization',
+    'extraUsageCurrency'
 ];
 
 interface UsageFieldRequirement {
@@ -132,7 +133,8 @@ function pickDefinedUsageFields(data: UsageData | null | undefined): Partial<Usa
         ...(data?.extraUsageEnabled !== undefined ? { extraUsageEnabled: data.extraUsageEnabled } : {}),
         ...(data?.extraUsageLimit !== undefined ? { extraUsageLimit: data.extraUsageLimit } : {}),
         ...(data?.extraUsageUsed !== undefined ? { extraUsageUsed: data.extraUsageUsed } : {}),
-        ...(data?.extraUsageUtilization !== undefined ? { extraUsageUtilization: data.extraUsageUtilization } : {})
+        ...(data?.extraUsageUtilization !== undefined ? { extraUsageUtilization: data.extraUsageUtilization } : {}),
+        ...(data?.extraUsageCurrency !== undefined ? { extraUsageCurrency: data.extraUsageCurrency } : {})
     };
 }
 

src/utils/usage-types.ts

@@ -19,6 +19,7 @@ export interface UsageData {
     extraUsageLimit?: number;      // in cents (divide by 100 for dollars)
     extraUsageUsed?: number;       // in cents (divide by 100 for dollars)
     extraUsageUtilization?: number; // percentage 0-100
+    extraUsageCurrency?: string;   // ISO 4217 currency code (e.g. 'USD', 'EUR')
     error?: UsageError;
 }
 

src/widgets/ExtraUsageRemaining.ts

@@ -8,6 +8,7 @@ import type {
 } from '../types/Widget';
 import { getUsageErrorMessage } from '../utils/usage';
 
+import { formatUsageCurrency } from './shared/currency';
 import {
     appendHideDisabledModifier,
     getHideExtraUsageDisabledKeybind,
@@ -54,7 +55,7 @@ export class ExtraUsageRemainingWidget implements Widget {
         const limitDollars = data.extraUsageLimit / 100;
         const usedDollars = data.extraUsageUsed / 100;
         const remaining = Math.max(0, limitDollars - usedDollars);
-        const formatted = `$${remaining.toLocaleString('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
+        const formatted = formatUsageCurrency(remaining, data.extraUsageCurrency);
 
         return formatRawOrLabeledValue(item, 'Overage Left: ', formatted);
     }

src/widgets/__tests__/ExtraUsageRemaining.test.ts

@@ -47,6 +47,19 @@ describe('ExtraUsageRemainingWidget', () => {
         }, context)).toBe('$3,894.00');
     });
 
+    it('formats remaining budget in the currency reported by the API', () => {
+        const widget = new ExtraUsageRemainingWidget();
+
+        expect(render(widget, { id: 'extra', type: 'extra-usage-remaining' }, {
+            usageData: {
+                extraUsageCurrency: 'EUR',
+                extraUsageEnabled: true,
+                extraUsageLimit: 400000,
+                extraUsageUsed: 10600
+            }
+        })).toBe('Overage Left: €3,894.00');
+    });
+
     it('clamps remaining budget at zero', () => {
         const widget = new ExtraUsageRemainingWidget();
 

src/widgets/__tests__/shared/currency.test.ts

@@ -0,0 +1,23 @@
+import {
+    describe,
+    expect,
+    it
+} from 'vitest';
+
+import { formatUsageCurrency } from '../../shared/currency';
+
+describe('formatUsageCurrency', () => {
+    it('defaults to USD when no currency is reported', () => {
+        expect(formatUsageCurrency(3894, undefined)).toBe('$3,894.00');
+    });
+
+    it('formats known ISO 4217 currency codes', () => {
+        expect(formatUsageCurrency(3894, 'USD')).toBe('$3,894.00');
+        expect(formatUsageCurrency(3894, 'EUR')).toBe('€3,894.00');
+        expect(formatUsageCurrency(5.42, 'GBP')).toBe('£5.42');
+    });
+
+    it('falls back to USD for invalid currency codes', () => {
+        expect(formatUsageCurrency(3894, 'not-a-currency')).toBe('$3,894.00');
+    });
+});

src/widgets/shared/currency.ts

@@ -0,0 +1,23 @@
+const FALLBACK_CURRENCY = 'USD';
+
+/**
+ * Formats a monetary amount using the ISO 4217 currency code reported by the
+ * usage API (extra_usage.currency), falling back to USD when absent or invalid.
+ */
+export function formatUsageCurrency(amount: number, currency: string | undefined): string {
+    try {
+        return amount.toLocaleString('en-US', {
+            style: 'currency',
+            currency: currency ?? FALLBACK_CURRENCY,
+            minimumFractionDigits: 2,
+            maximumFractionDigits: 2
+        });
+    } catch {
+        return amount.toLocaleString('en-US', {
+            style: 'currency',
+            currency: FALLBACK_CURRENCY,
+            minimumFractionDigits: 2,
+            maximumFractionDigits: 2
+        });
+    }
+}