diff --git a/packages/ui/src/lib/i18n/messages/de.ts b/packages/ui/src/lib/i18n/messages/de.ts
index d4c24849..6f0e19d3 100644
--- a/packages/ui/src/lib/i18n/messages/de.ts
+++ b/packages/ui/src/lib/i18n/messages/de.ts
@@ -2910,7 +2910,7 @@ export const dict = {
   'quota.window.premium': 'Premium-Interaktionen',
   'quota.window.chat': 'Chat-Anfragen',
   'quota.window.completions': 'Vervollständigungen',
-  'quota.window.premiumInteractions': 'Premium-Interaktionen',
+  'quota.window.premiumInteractions': 'KI-Guthaben',
   'terminalView.actions.attachSelection': 'Ausgewählte Ausgabe anhängen',
   'terminalView.actions.restart': 'Terminal neu starten',
   'chat.message.terminalContext': '{terminal}, Zeilen {start}-{end}',
diff --git a/packages/ui/src/lib/i18n/messages/en.ts b/packages/ui/src/lib/i18n/messages/en.ts
index cedf598c..47104589 100644
--- a/packages/ui/src/lib/i18n/messages/en.ts
+++ b/packages/ui/src/lib/i18n/messages/en.ts
@@ -3111,7 +3111,7 @@ export const dict = {
   'quota.window.premium': 'Premium Interactions',
   'quota.window.chat': 'Chat Requests',
   'quota.window.completions': 'Completions',
-  'quota.window.premiumInteractions': 'Premium interactions',
+  'quota.window.premiumInteractions': 'AI Credits',
   'chat.workStatus.ariaLabel': 'Work status',
   'chat.workStatus.context.label': 'Context',
   'chat.workStatus.git.changedFileSingle': '{count} file changed',
diff --git a/packages/ui/src/lib/i18n/messages/es.ts b/packages/ui/src/lib/i18n/messages/es.ts
index 9c836683..f0f9f48d 100644
--- a/packages/ui/src/lib/i18n/messages/es.ts
+++ b/packages/ui/src/lib/i18n/messages/es.ts
@@ -3112,7 +3112,7 @@ export const dict: Record<I18nKey, string> = {
   "quota.window.premium": "Premium Interactions",
   "quota.window.chat": "Chat Requests",
   "quota.window.completions": "Completions",
-  "quota.window.premiumInteractions": "Premium interactions",
+  "quota.window.premiumInteractions": "Créditos de IA",
   'chat.workStatus.ariaLabel': 'Estado del trabajo',
   'chat.workStatus.context.label': 'Contexto',
   'chat.workStatus.git.changedFileSingle': '{count} archivo modificado',
diff --git a/packages/ui/src/lib/i18n/messages/fr.ts b/packages/ui/src/lib/i18n/messages/fr.ts
index 2bbd63d7..eae42bb2 100644
--- a/packages/ui/src/lib/i18n/messages/fr.ts
+++ b/packages/ui/src/lib/i18n/messages/fr.ts
@@ -2803,7 +2803,7 @@ export const dict = {
   'quota.window.premium': 'Interactions premium',
   'quota.window.chat': 'Requêtes de chat',
   'quota.window.completions': 'Complétions',
-  'quota.window.premiumInteractions': 'Interactions premium',
+  'quota.window.premiumInteractions': 'Crédits IA',
   'layout.mainTab.diagram': 'Diagramme',
   'mobile.nav.aria': 'Navigation mobile',
   'mobile.connect.welcome.title': 'Se connecter à OpenChamber',
diff --git a/packages/ui/src/lib/i18n/messages/ja.ts b/packages/ui/src/lib/i18n/messages/ja.ts
index f47ed145..cddf221f 100644
--- a/packages/ui/src/lib/i18n/messages/ja.ts
+++ b/packages/ui/src/lib/i18n/messages/ja.ts
@@ -3110,7 +3110,7 @@ export const dict: Record<I18nKey, string> = {
   'onboarding.localSetup.actions.checkAndContinue': 'インストール完了、確認して続行',
   'onboarding.localSetup.status.autoContinue': '検出され次第自動的に続行します。',
   'updateDialog.changelog.title': '新機能',
-  'quota.window.premiumInteractions': 'プレミアムインタラクション',
+  'quota.window.premiumInteractions': 'AIクレジット',
 
   'chat.workStatus.ariaLabel': '作業状況',
   'chat.workStatus.context.label': 'コンテキスト',
diff --git a/packages/ui/src/lib/i18n/messages/ko.ts b/packages/ui/src/lib/i18n/messages/ko.ts
index 3f3edd34..4002cd41 100644
--- a/packages/ui/src/lib/i18n/messages/ko.ts
+++ b/packages/ui/src/lib/i18n/messages/ko.ts
@@ -3111,7 +3111,7 @@ export const dict: Record<I18nKey, string> = {
   'quota.window.premium': 'Premium Interactions',
   'quota.window.chat': 'Chat Requests',
   'quota.window.completions': 'Completions',
-  'quota.window.premiumInteractions': 'Premium interactions',
+  'quota.window.premiumInteractions': 'AI 크레딧',
   'chat.workStatus.ariaLabel': '작업 상태',
   'chat.workStatus.context.label': '컨텍스트',
   'chat.workStatus.git.changedFileSingle': '파일 {count}개 변경됨',
diff --git a/packages/ui/src/lib/i18n/messages/pl.ts b/packages/ui/src/lib/i18n/messages/pl.ts
index 3c0556f5..996d2af8 100644
--- a/packages/ui/src/lib/i18n/messages/pl.ts
+++ b/packages/ui/src/lib/i18n/messages/pl.ts
@@ -3128,7 +3128,7 @@ export const dict: Record<I18nKey, string> = {
   'quota.window.premium': 'Premium Interactions',
   'quota.window.chat': 'Chat Requests',
   'quota.window.completions': 'Completions',
-  'quota.window.premiumInteractions': 'Premium interactions',
+  'quota.window.premiumInteractions': 'Kredyty AI',
   'chat.workStatus.ariaLabel': 'Stan pracy',
   'chat.workStatus.context.label': 'Kontekst',
   'chat.workStatus.git.changedFileSingle': 'Zmieniono {count} plik',
diff --git a/packages/ui/src/lib/i18n/messages/pt-BR.ts b/packages/ui/src/lib/i18n/messages/pt-BR.ts
index a4b53b0c..6c9605f9 100644
--- a/packages/ui/src/lib/i18n/messages/pt-BR.ts
+++ b/packages/ui/src/lib/i18n/messages/pt-BR.ts
@@ -3112,7 +3112,7 @@ export const dict: Record<I18nKey, string> = {
   "quota.window.premium": "Premium Interactions",
   "quota.window.chat": "Chat Requests",
   "quota.window.completions": "Completions",
-  "quota.window.premiumInteractions": "Premium interactions",
+  "quota.window.premiumInteractions": "Créditos de IA",
   'chat.workStatus.ariaLabel': 'Status do trabalho',
   'chat.workStatus.context.label': 'Contexto',
   'chat.workStatus.git.changedFileSingle': '{count} arquivo alterado',
diff --git a/packages/ui/src/lib/i18n/messages/uk.ts b/packages/ui/src/lib/i18n/messages/uk.ts
index 9ef4ae3a..a79881fe 100644
--- a/packages/ui/src/lib/i18n/messages/uk.ts
+++ b/packages/ui/src/lib/i18n/messages/uk.ts
@@ -3112,7 +3112,7 @@ export const dict: Record<I18nKey, string> = {
   "quota.window.premium": "Premium Interactions",
   "quota.window.chat": "Chat Requests",
   "quota.window.completions": "Completions",
-  "quota.window.premiumInteractions": "Premium interactions",
+  "quota.window.premiumInteractions": "Кредити ШІ",
   'chat.workStatus.ariaLabel': 'Стан роботи',
   'chat.workStatus.context.label': 'Контекст',
   'chat.workStatus.git.changedFileSingle': 'Змінено {count} файл',
diff --git a/packages/ui/src/lib/i18n/messages/zh-CN.ts b/packages/ui/src/lib/i18n/messages/zh-CN.ts
index 1a39b4b9..7b9d57b7 100644
--- a/packages/ui/src/lib/i18n/messages/zh-CN.ts
+++ b/packages/ui/src/lib/i18n/messages/zh-CN.ts
@@ -3112,7 +3112,7 @@ export const dict: Record<I18nKey, string> = {
   'quota.window.premium': 'Premium Interactions',
   'quota.window.chat': 'Chat Requests',
   'quota.window.completions': 'Completions',
-  'quota.window.premiumInteractions': 'Premium interactions',
+  'quota.window.premiumInteractions': 'AI 点数',
   'chat.workStatus.ariaLabel': '工作状态',
   'chat.workStatus.context.label': '上下文',
   'chat.workStatus.git.changedFileSingle': '已更改 {count} 个文件',
diff --git a/packages/ui/src/lib/i18n/messages/zh-TW.ts b/packages/ui/src/lib/i18n/messages/zh-TW.ts
index 97421782..bdbe84bc 100644
--- a/packages/ui/src/lib/i18n/messages/zh-TW.ts
+++ b/packages/ui/src/lib/i18n/messages/zh-TW.ts
@@ -3111,7 +3111,7 @@ export const dict: Record<I18nKey, string> = {
   'quota.window.premium': 'Premium Interactions',
   'quota.window.chat': 'Chat Requests',
   'quota.window.completions': 'Completions',
-  'quota.window.premiumInteractions': 'Premium interactions',
+  'quota.window.premiumInteractions': 'AI 點數',
   'chat.workStatus.ariaLabel': '工作狀態',
   'chat.workStatus.context.label': '上下文',
   'chat.workStatus.git.changedFileSingle': '已變更 {count} 個檔案',
diff --git a/packages/ui/src/lib/quota/utils.test.ts b/packages/ui/src/lib/quota/utils.test.ts
index afca3d75..abda6e48 100644
--- a/packages/ui/src/lib/quota/utils.test.ts
+++ b/packages/ui/src/lib/quota/utils.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, test } from 'bun:test';
 
-import { clampPercent, formatPercent } from './utils';
+import { clampPercent, formatPercent, formatWindowLabel } from './utils';
 
 describe('quota utils', () => {
   test('treats non-finite percentages as missing', () => {
@@ -10,4 +10,9 @@ describe('quota utils', () => {
     expect(formatPercent(Infinity)).toBe('-');
     expect(formatPercent(-Infinity)).toBe('-');
   });
+
+  test('labels Copilot usage as AI Credits without changing generic premium usage', () => {
+    expect(formatWindowLabel('premium')).toBe('Premium Interactions');
+    expect(formatWindowLabel('premium_interactions')).toBe('AI Credits');
+  });
 });
diff --git a/packages/vscode/src/quotaProviders.test.ts b/packages/vscode/src/quotaProviders.test.ts
index 0ab8938c..783583a5 100644
--- a/packages/vscode/src/quotaProviders.test.ts
+++ b/packages/vscode/src/quotaProviders.test.ts
@@ -19,6 +19,7 @@ const AUTH = JSON.stringify({
   'opencode-go': { key: 'test-token' },
   'zai-coding-plan': { key: 'test-token' },
   deepseek: { key: 'test-token' },
+  'github-copilot': { access: 'test-token' },
   anthropic: { access: 'test-token', refresh: 'test-refresh' },
 });
 ((fs as unknown) as { existsSync: () => boolean }).existsSync = () => true;
@@ -196,6 +197,71 @@ describe('Codex quota provider (VS Code parity)', () => {
   });
 });
 
+describe('GitHub Copilot quota provider (VS Code parity)', () => {
+  test('exposes only premium interactions as the primary usage window', async () => {
+    stubFetchReturning(() => Promise.resolve(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        chat: { entitlement: 100, remaining: 80 },
+        completions: { entitlement: 1000, remaining: 900 },
+        premium_interactions: { entitlement: 300, remaining: 225 },
+      },
+    })));
+
+    const result = await fetchQuotaForProvider('github-copilot');
+
+    assert.equal(result.ok, true);
+    assert.deepEqual(Object.keys(result.usage!.windows), ['premium_interactions']);
+    assert.equal(result.usage!.windows.premium_interactions!.usedPercent, 25);
+    assert.equal(result.usage!.windows.premium_interactions!.valueLabel, '225 / 300 left');
+  });
+
+  test('add-on path mirrors the primary window shaping', async () => {
+    stubFetchReturning(() => Promise.resolve(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        premium_interactions: { entitlement: 300, remaining: 225 },
+      },
+    })));
+
+    const result = await fetchQuotaForProvider('github-copilot-addon');
+
+    assert.equal(result.ok, true);
+    assert.deepEqual(Object.keys(result.usage!.windows), ['premium_interactions']);
+    assert.equal(result.usage!.windows.premium_interactions!.usedPercent, 25);
+  });
+
+  test('reports unlimited plans without a percent', async () => {
+    stubFetchReturning(() => Promise.resolve(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        premium_interactions: { unlimited: true, entitlement: -1, remaining: -1 },
+      },
+    })));
+
+    const result = await fetchQuotaForProvider('github-copilot');
+
+    assert.equal(result.ok, true);
+    assert.equal(result.usage!.windows.premium_interactions!.usedPercent, null);
+    assert.equal(result.usage!.windows.premium_interactions!.valueLabel, 'Unlimited');
+  });
+
+  test('falls back to percent_remaining when entitlement is unusable', async () => {
+    stubFetchReturning(() => Promise.resolve(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        premium_interactions: { entitlement: 0, remaining: 0, percent_remaining: 75.5 },
+      },
+    })));
+
+    const result = await fetchQuotaForProvider('github-copilot');
+
+    assert.equal(result.ok, true);
+    assert.ok(Math.abs(result.usage!.windows.premium_interactions!.usedPercent! - 24.5) < 1e-9);
+    assert.equal(result.usage!.windows.premium_interactions!.valueLabel, undefined);
+  });
+});
+
 describe('Claude quota provider (VS Code parity)', () => {
   test('parses current limits, model-scoped limits, and extra usage', async () => {
     stubFetchReturning(() => Promise.resolve(mockResponse({
diff --git a/packages/vscode/src/quotaProviders.ts b/packages/vscode/src/quotaProviders.ts
index c70b43b7..a9ce3204 100644
--- a/packages/vscode/src/quotaProviders.ts
+++ b/packages/vscode/src/quotaProviders.ts
@@ -1465,14 +1465,35 @@ const buildCopilotWindows = (payload: Record<string, unknown>) => {
   const resetAt = toTimestamp(payload.quota_reset_date);
   const windows: Record<string, UsageWindow> = {};
 
+  // Mirrors the quota semantics of microsoft/vscode-copilot-chat
+  // (CopilotUserQuotaInfo): each snapshot carries entitlement, remaining,
+  // unlimited, and percent_remaining. Unlimited plans report no usable
+  // entitlement; percent_remaining is a server-computed fallback.
   const addWindow = (label: string, snapshot?: Record<string, unknown>) => {
     if (!snapshot) return;
+
+    if (snapshot.unlimited === true) {
+      windows[label] = toUsageWindow({
+        usedPercent: null,
+        windowSeconds: null,
+        resetAt,
+        valueLabel: 'Unlimited',
+      });
+      return;
+    }
+
     const entitlement = toNumber(snapshot.entitlement);
     const remaining = toNumber(snapshot.remaining);
-    const usedPercent = entitlement && remaining !== null
-      ? Math.max(0, Math.min(100, 100 - (remaining / entitlement) * 100))
+    let usedPercent = entitlement !== null && entitlement > 0 && remaining !== null
+      ? Math.min(100, Math.max(0, 100 - (remaining / entitlement) * 100))
       : null;
-    const valueLabel = entitlement !== null && remaining !== null
+    if (usedPercent === null) {
+      const percentRemaining = toNumber(snapshot.percent_remaining);
+      if (percentRemaining !== null) {
+        usedPercent = Math.min(100, Math.max(0, 100 - percentRemaining));
+      }
+    }
+    const valueLabel = entitlement !== null && entitlement > 0 && remaining !== null
       ? `${remaining.toFixed(0)} / ${entitlement.toFixed(0)} left`
       : null;
     windows[label] = toUsageWindow({
@@ -1483,9 +1504,7 @@ const buildCopilotWindows = (payload: Record<string, unknown>) => {
     });
   };
 
-  addWindow('chat', quota.chat as Record<string, unknown> | undefined);
-  addWindow('completions', quota.completions as Record<string, unknown> | undefined);
-  addWindow('premium', quota.premium_interactions as Record<string, unknown> | undefined);
+  addWindow('premium_interactions', quota.premium_interactions as Record<string, unknown> | undefined);
 
   return windows;
 };
@@ -1582,15 +1601,12 @@ const fetchCopilotAddonQuota = async (): Promise<ProviderResult> => {
     }
 
     const payload = await response.json() as Record<string, unknown>;
-    const windows = buildCopilotWindows(payload);
-    const premium = windows.premium ? { premium: windows.premium } : windows;
-
     return buildResult({
       providerId: 'github-copilot-addon',
       providerName: 'GitHub Copilot Add-on',
       ok: true,
       configured: true,
-      usage: { windows: premium },
+      usage: { windows: buildCopilotWindows(payload) },
     });
   } catch (error) {
     return buildResult({
diff --git a/packages/web/server/lib/quota/DOCUMENTATION.md b/packages/web/server/lib/quota/DOCUMENTATION.md
index 83e905a4..1897336b 100644
--- a/packages/web/server/lib/quota/DOCUMENTATION.md
+++ b/packages/web/server/lib/quota/DOCUMENTATION.md
@@ -97,6 +97,25 @@ In 2025/2026 MiniMax rebranded "Coding Plan" to "Token Plan" alongside the M3 mo
 
 The provider computes `usedPercent` from whichever of `used`/`remaining` is present (`used` takes precedence when both exist) rather than assuming one field name. Both `packages/web/server/lib/quota/providers/kimi.js` and `packages/vscode/src/quotaProviders.ts` (`fetchKimiQuota`) must stay in sync — the VS Code extension duplicates this parsing logic rather than importing it.
 
+## GitHub Copilot quota semantics
+
+GitHub Copilot usage exposes only the `premium_interactions` snapshot as the
+`premium_interactions` window. Shared UI labels that window **AI Credits** and treats it as
+the provider's primary usage marker. Legacy chat-request quota and unlimited
+completion quota are intentionally omitted. Keep
+`packages/web/server/lib/quota/providers/copilot.js` and
+`packages/vscode/src/quotaProviders.ts` in sync.
+
+The `/copilot_internal/user` endpoint is undocumented; its quota semantics mirror
+what `microsoft/vscode-copilot-chat` consumes (`CopilotUserQuotaInfo`). Each
+snapshot carries `entitlement`, `remaining`, `unlimited`, and
+`percent_remaining`. Providers must honor these rules:
+
+- `unlimited: true` renders a percent-less window with an "Unlimited" value label.
+- Percent math requires a positive `entitlement`; entitlements of `0`, `-1`, or null are unusable.
+- When entitlement/remaining are unusable, fall back to `100 - percent_remaining`.
+- Snapshots other than `premium_interactions` (legacy annual plans) yield zero windows.
+
 ## Notes for contributors
 - Keep provider IDs stable; clients use them directly.
 - Avoid adding alias-based dispatch in `fetchQuotaForProvider`; dispatch currently expects exact provider IDs.
diff --git a/packages/web/server/lib/quota/providers/copilot.js b/packages/web/server/lib/quota/providers/copilot.js
index 964f2f71..538411c8 100644
--- a/packages/web/server/lib/quota/providers/copilot.js
+++ b/packages/web/server/lib/quota/providers/copilot.js
@@ -13,14 +13,35 @@ const buildCopilotWindows = (payload) => {
   const resetAt = toTimestamp(payload?.quota_reset_date);
   const windows = {};
 
+  // Mirrors the quota semantics of microsoft/vscode-copilot-chat
+  // (CopilotUserQuotaInfo): each snapshot carries entitlement, remaining,
+  // unlimited, and percent_remaining. Unlimited plans report no usable
+  // entitlement; percent_remaining is a server-computed fallback.
   const addWindow = (label, snapshot) => {
     if (!snapshot) return;
+
+    if (snapshot.unlimited === true) {
+      windows[label] = toUsageWindow({
+        usedPercent: null,
+        windowSeconds: null,
+        resetAt,
+        valueLabel: 'Unlimited'
+      });
+      return;
+    }
+
     const entitlement = toNumber(snapshot.entitlement);
     const remaining = toNumber(snapshot.remaining);
-    const usedPercent = entitlement && remaining !== null
-      ? Math.max(0, 100 - (remaining / entitlement) * 100)
+    let usedPercent = entitlement !== null && entitlement > 0 && remaining !== null
+      ? Math.min(100, Math.max(0, 100 - (remaining / entitlement) * 100))
       : null;
-    const valueLabel = entitlement !== null && remaining !== null
+    if (usedPercent === null) {
+      const percentRemaining = toNumber(snapshot.percent_remaining);
+      if (percentRemaining !== null) {
+        usedPercent = Math.min(100, Math.max(0, 100 - percentRemaining));
+      }
+    }
+    const valueLabel = entitlement !== null && entitlement > 0 && remaining !== null
       ? `${remaining.toFixed(0)} / ${entitlement.toFixed(0)} left`
       : null;
     windows[label] = toUsageWindow({
@@ -31,9 +52,7 @@ const buildCopilotWindows = (payload) => {
     });
   };
 
-  addWindow('chat', quota.chat);
-  addWindow('completions', quota.completions);
-  addWindow('premium', quota.premium_interactions);
+  addWindow('premium_interactions', quota.premium_interactions);
 
   return windows;
 };
@@ -143,15 +162,12 @@ export const fetchQuotaAddon = async () => {
     }
 
     const payload = await response.json();
-    const windows = buildCopilotWindows(payload);
-    const premium = windows.premium ? { premium: windows.premium } : windows;
-
     return buildResult({
       providerId: providerIdAddon,
       providerName: providerNameAddon,
       ok: true,
       configured: true,
-      usage: { windows: premium }
+      usage: { windows: buildCopilotWindows(payload) }
     });
   } catch (error) {
     return buildResult({
diff --git a/packages/web/server/lib/quota/providers/copilot.test.js b/packages/web/server/lib/quota/providers/copilot.test.js
new file mode 100644
index 00000000..5038ed49
--- /dev/null
+++ b/packages/web/server/lib/quota/providers/copilot.test.js
@@ -0,0 +1,78 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+vi.mock('../../opencode/auth.js', () => ({
+  readAuthFile: () => ({ 'github-copilot': { access: 'test-token' } }),
+}));
+
+import { fetchQuota, fetchQuotaAddon } from './copilot.js';
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+});
+
+const payload = {
+  quota_reset_date: '2026-09-01T00:00:00Z',
+  quota_snapshots: {
+    chat: { entitlement: 100, remaining: 80 },
+    completions: { entitlement: 1000, remaining: 900 },
+    premium_interactions: { entitlement: 300, remaining: 225 },
+  },
+};
+
+const mockResponse = (body = payload) => ({
+  ok: true,
+  status: 200,
+  json: async () => body,
+});
+
+describe('GitHub Copilot quota provider', () => {
+  it.each([
+    ['primary provider', fetchQuota],
+    ['add-on provider', fetchQuotaAddon],
+  ])('exposes only premium interactions for the %s', async (_name, fetchProviderQuota) => {
+    vi.stubGlobal('fetch', vi.fn().mockResolvedValue(mockResponse()));
+
+    const result = await fetchProviderQuota();
+
+    expect(result.ok).toBe(true);
+    expect(Object.keys(result.usage.windows)).toEqual(['premium_interactions']);
+    expect(result.usage.windows.premium_interactions.usedPercent).toBe(25);
+    expect(result.usage.windows.premium_interactions.valueLabel).toBe('225 / 300 left');
+  });
+
+  it.each([
+    ['primary provider', fetchQuota],
+    ['add-on provider', fetchQuotaAddon],
+  ])('reports unlimited plans without a percent for the %s', async (_name, fetchProviderQuota) => {
+    vi.stubGlobal('fetch', vi.fn().mockResolvedValue(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        premium_interactions: { unlimited: true, entitlement: -1, remaining: -1 },
+      },
+    })));
+
+    const result = await fetchProviderQuota();
+
+    expect(result.ok).toBe(true);
+    expect(result.usage.windows.premium_interactions.usedPercent).toBeNull();
+    expect(result.usage.windows.premium_interactions.valueLabel).toBe('Unlimited');
+  });
+
+  it.each([
+    ['primary provider', fetchQuota],
+    ['add-on provider', fetchQuotaAddon],
+  ])('falls back to percent_remaining when entitlement is unusable for the %s', async (_name, fetchProviderQuota) => {
+    vi.stubGlobal('fetch', vi.fn().mockResolvedValue(mockResponse({
+      quota_reset_date: '2026-09-01T00:00:00Z',
+      quota_snapshots: {
+        premium_interactions: { entitlement: 0, remaining: 0, percent_remaining: 75.5 },
+      },
+    })));
+
+    const result = await fetchProviderQuota();
+
+    expect(result.ok).toBe(true);
+    expect(result.usage.windows.premium_interactions.usedPercent).toBeCloseTo(24.5);
+    expect(result.usage.windows.premium_interactions.valueLabel ?? null).toBeNull();
+  });
+});