diff --git a/packages/app/src/components/session-context-usage.tsx b/packages/app/src/components/session-context-usage.tsx
index 47030aa17..08ae4d319 100644
--- a/packages/app/src/components/session-context-usage.tsx
+++ b/packages/app/src/components/session-context-usage.tsx
@@ -39,7 +39,7 @@ export function SessionContextUsage(props: SessionContextUsageProps) {
 
   const usd = createMemo(
     () =>
-      new Intl.NumberFormat(language.locale(), {
+      new Intl.NumberFormat(language.intl(), {
         style: "currency",
         currency: "USD",
       }),
@@ -77,7 +77,7 @@ export function SessionContextUsage(props: SessionContextUsageProps) {
         {(ctx) => (
           <>
             <div class="flex items-center gap-2">
-              <span class="text-text-invert-strong">{ctx().total.toLocaleString(language.locale())}</span>
+              <span class="text-text-invert-strong">{ctx().total.toLocaleString(language.intl())}</span>
               <span class="text-text-invert-base">{language.t("context.usage.tokens")}</span>
             </div>
             <div class="flex items-center gap-2">
diff --git a/packages/app/src/components/session/session-context-tab.tsx b/packages/app/src/components/session/session-context-tab.tsx
index 582aa3391..39eb4b4c0 100644
--- a/packages/app/src/components/session/session-context-tab.tsx
+++ b/packages/app/src/components/session/session-context-tab.tsx
@@ -128,7 +128,7 @@ export function SessionContextTab() {
 
   const usd = createMemo(
     () =>
-      new Intl.NumberFormat(language.locale(), {
+      new Intl.NumberFormat(language.intl(), {
         style: "currency",
         currency: "USD",
       }),
@@ -136,7 +136,7 @@ export function SessionContextTab() {
 
   const metrics = createMemo(() => getSessionContextMetrics(messages(), sync.data.provider.all))
   const ctx = createMemo(() => metrics().context)
-  const formatter = createMemo(() => createSessionContextFormatter(language.locale()))
+  const formatter = createMemo(() => createSessionContextFormatter(language.intl()))
 
   const cost = createMemo(() => {
     return usd().format(metrics().totalCost)
@@ -200,7 +200,7 @@ export function SessionContextTab() {
 
   const stats = [
     { label: "context.stats.session", value: () => info()?.title ?? params.id ?? "—" },
-    { label: "context.stats.messages", value: () => counts().all.toLocaleString(language.locale()) },
+    { label: "context.stats.messages", value: () => counts().all.toLocaleString(language.intl()) },
     { label: "context.stats.provider", value: providerLabel },
     { label: "context.stats.model", value: modelLabel },
     { label: "context.stats.limit", value: () => formatter().number(ctx()?.limit) },
@@ -213,8 +213,8 @@ export function SessionContextTab() {
       label: "context.stats.cacheTokens",
       value: () => `${formatter().number(ctx()?.cacheRead)} / ${formatter().number(ctx()?.cacheWrite)}`,
     },
-    { label: "context.stats.userMessages", value: () => counts().user.toLocaleString(language.locale()) },
-    { label: "context.stats.assistantMessages", value: () => counts().assistant.toLocaleString(language.locale()) },
+    { label: "context.stats.userMessages", value: () => counts().user.toLocaleString(language.intl()) },
+    { label: "context.stats.assistantMessages", value: () => counts().assistant.toLocaleString(language.intl()) },
     { label: "context.stats.totalCost", value: cost },
     { label: "context.stats.sessionCreated", value: () => formatter().time(info()?.time.created) },
     { label: "context.stats.lastActivity", value: () => formatter().time(ctx()?.message.time.created) },
@@ -307,7 +307,7 @@ export function SessionContextTab() {
                   <div class="flex items-center gap-1 text-11-regular text-text-weak">
                     <div class="size-2 rounded-sm" style={{ "background-color": BREAKDOWN_COLOR[segment.key] }} />
                     <div>{breakdownLabel(segment.key)}</div>
-                    <div class="text-text-weaker">{segment.percent.toLocaleString(language.locale())}%</div>
+                    <div class="text-text-weaker">{segment.percent.toLocaleString(language.intl())}%</div>
                   </div>
                 )}
               </For>
diff --git a/packages/app/src/components/session/session-new-view.tsx b/packages/app/src/components/session/session-new-view.tsx
index 79a20430e..f2ecd5150 100644
--- a/packages/app/src/components/session/session-new-view.tsx
+++ b/packages/app/src/components/session/session-new-view.tsx
@@ -70,7 +70,7 @@ export function NewSessionView(props: NewSessionViewProps) {
               {language.t("session.new.lastModified")}&nbsp;
               <span class="text-text-strong">
                 {DateTime.fromMillis(project().time.updated ?? project().time.created)
-                  .setLocale(language.locale())
+                  .setLocale(language.intl())
                   .toRelative()}
               </span>
             </div>
diff --git a/packages/app/src/context/language.tsx b/packages/app/src/context/language.tsx
index 50cc302f4..be1a1769b 100644
--- a/packages/app/src/context/language.tsx
+++ b/packages/app/src/context/language.tsx
@@ -84,6 +84,26 @@ const LOCALES: readonly Locale[] = [
   "tr",
 ]
 
+const INTL: Record<Locale, string> = {
+  en: "en",
+  zh: "zh-Hans",
+  zht: "zh-Hant",
+  ko: "ko",
+  de: "de",
+  es: "es",
+  fr: "fr",
+  da: "da",
+  ja: "ja",
+  pl: "pl",
+  ru: "ru",
+  ar: "ar",
+  no: "nb-NO",
+  br: "pt-BR",
+  th: "th",
+  bs: "bs",
+  tr: "tr",
+}
+
 const LABEL_KEY: Record<Locale, keyof Dictionary> = {
   en: "language.en",
   zh: "language.zh",
@@ -197,6 +217,7 @@ export const { use: useLanguage, provider: LanguageProvider } = createSimpleCont
     )
 
     const locale = createMemo<Locale>(() => normalizeLocale(store.locale))
+    const intl = createMemo(() => INTL[locale()])
 
     const dict = createMemo<Dictionary>(() => DICT[locale()])
 
@@ -213,6 +234,7 @@ export const { use: useLanguage, provider: LanguageProvider } = createSimpleCont
     return {
       ready,
       locale,
+      intl,
       locales: LOCALES,
       label,
       t,