From b5b945fc2ceddaf8fca3ded8ab55b3830286cb66 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 12:34:38 +1000
Subject: [PATCH 1/9] silence MISSING_TRANSLATION warnings for fallback locales

---
 ui/desktop/src/i18n/i18n.test.ts | 42 ++++++++++++++++++++++++++++----
 ui/desktop/src/i18n/index.ts     | 17 +++++++++----
 2 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 808883e32e39..95c45459fbc8 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -1,6 +1,15 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { getLocale } from './index';
 
+const englishMessages = {
+  shared: 'English shared message',
+  englishOnly: 'English fallback message',
+};
+
+const zhCnMessages = {
+  shared: 'Chinese shared message',
+};
+
 // Helper to mock window.appConfig for tests
 function mockAppConfig(values: Record<string, unknown>) {
   (window as unknown as Record<string, unknown>).appConfig = {
@@ -61,17 +70,40 @@ describe('getLocale', () => {
 });
 
 describe('loadMessages', () => {
-  it('returns empty object for English locale', async () => {
+  afterEach(() => {
+    vi.doUnmock('./compiled/en.json');
+    vi.doUnmock('./compiled/zh-CN.json');
+    vi.resetModules();
+  });
+
+  async function loadMessagesWithMockedCatalogs() {
+    vi.resetModules();
+    vi.doMock('./compiled/en.json', () => ({ default: englishMessages }));
+    vi.doMock('./compiled/zh-CN.json', () => ({ default: zhCnMessages }));
+
     const { loadMessages } = await import('./index');
+    return loadMessages;
+  }
+
+  it('returns compiled English messages for English locale', async () => {
+    const loadMessages = await loadMessagesWithMockedCatalogs();
     const messages = await loadMessages('en');
-    expect(messages).toEqual({});
+    expect(messages).toEqual(englishMessages);
   });
 
-  it('returns empty object for unsupported locale (with warning)', async () => {
+  it('merges locale messages over English fallback messages', async () => {
+    const loadMessages = await loadMessagesWithMockedCatalogs();
+    const messages = await loadMessages('zh-CN');
+
+    expect(messages.shared).toBe(zhCnMessages.shared);
+    expect(messages.englishOnly).toBe(englishMessages.englishOnly);
+  });
+
+  it('returns English messages for unsupported locale (with warning)', async () => {
     const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-    const { loadMessages } = await import('./index');
+    const loadMessages = await loadMessagesWithMockedCatalogs();
     const messages = await loadMessages('xx');
-    expect(messages).toEqual({});
+    expect(messages).toEqual(englishMessages);
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
   });
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index 07a6d23c828d..bc2043971e2a 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -92,22 +92,29 @@ export const currentMessageLocale = resolvedLocale.messageLocale;
 
 /**
  * Load compiled messages for a given locale.
- * Returns an empty object for English (react-intl uses defaultMessage as fallback).
+ * English messages are always loaded as the fallback catalog so regional
+ * English locales can keep their locale for date/number formatting without
+ * triggering missing translation warnings for every message.
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
+  const englishMod = await import('./compiled/en.json');
+  const englishMessages = englishMod.default ?? englishMod;
+
   if (locale === 'en') {
-    // English strings live in source code as defaultMessage — no catalog needed.
-    return {};
+    return englishMessages;
   }
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
     const mod = await import(`./compiled/${locale}.json`);
-    return mod.default ?? mod;
+    return {
+      ...englishMessages,
+      ...(mod.default ?? mod),
+    };
   } catch {
     console.warn(
       `[i18n] No message catalog found for locale "${locale}", falling back to English.`
     );
-    return {};
+    return englishMessages;
   }
 }

From eb2c2bf8735f62e4df2b706f72b049c7640de946 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 13:03:56 +1000
Subject: [PATCH 2/9] fixed typecheck

---
 ui/desktop/src/i18n/index.ts | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index bc2043971e2a..098ae1872c54 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -90,6 +90,11 @@ export const currentLocale = resolvedLocale.locale;
 /** Base language for loading message catalogs (e.g. "en"). */
 export const currentMessageLocale = resolvedLocale.messageLocale;
 
+async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
+  const mod = await import(`./compiled/${locale}.json`);
+  return (mod.default ?? mod) as Record<string, string>;
+}
+
 /**
  * Load compiled messages for a given locale.
  * English messages are always loaded as the fallback catalog so regional
@@ -97,8 +102,7 @@ export const currentMessageLocale = resolvedLocale.messageLocale;
  * triggering missing translation warnings for every message.
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
-  const englishMod = await import('./compiled/en.json');
-  const englishMessages = englishMod.default ?? englishMod;
+  const englishMessages = await loadCompiledMessages('en');
 
   if (locale === 'en') {
     return englishMessages;
@@ -106,10 +110,10 @@ export async function loadMessages(locale: string): Promise<Record<string, strin
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
-    const mod = await import(`./compiled/${locale}.json`);
+    const messages = await loadCompiledMessages(locale);
     return {
       ...englishMessages,
-      ...(mod.default ?? mod),
+      ...messages,
     };
   } catch {
     console.warn(

From d58242c3c5f42393e9019eadbe864fe3fd193b7c Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 13:21:10 +1000
Subject: [PATCH 3/9] fixed tests

---
 ui/desktop/src/i18n/i18n.test.ts | 42 +++++++++++++++-----------------
 ui/desktop/src/i18n/index.ts     | 13 +++++++---
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 95c45459fbc8..70b6ecdec40f 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
-import { getLocale } from './index';
+import { getLocale, loadMessagesWithCatalogLoader } from './index';
 
 const englishMessages = {
   shared: 'English shared message',
@@ -70,39 +70,37 @@ describe('getLocale', () => {
 });
 
 describe('loadMessages', () => {
-  afterEach(() => {
-    vi.doUnmock('./compiled/en.json');
-    vi.doUnmock('./compiled/zh-CN.json');
-    vi.resetModules();
-  });
-
-  async function loadMessagesWithMockedCatalogs() {
-    vi.resetModules();
-    vi.doMock('./compiled/en.json', () => ({ default: englishMessages }));
-    vi.doMock('./compiled/zh-CN.json', () => ({ default: zhCnMessages }));
-
-    const { loadMessages } = await import('./index');
-    return loadMessages;
-  }
-
   it('returns compiled English messages for English locale', async () => {
-    const loadMessages = await loadMessagesWithMockedCatalogs();
-    const messages = await loadMessages('en');
+    const loadCatalog = vi.fn().mockResolvedValue(englishMessages);
+    const messages = await loadMessagesWithCatalogLoader('en', loadCatalog);
+
     expect(messages).toEqual(englishMessages);
+    expect(loadCatalog).toHaveBeenCalledOnce();
+    expect(loadCatalog).toHaveBeenCalledWith('en');
   });
 
   it('merges locale messages over English fallback messages', async () => {
-    const loadMessages = await loadMessagesWithMockedCatalogs();
-    const messages = await loadMessages('zh-CN');
+    const loadCatalog = vi.fn(async (locale: string) =>
+      locale === 'zh-CN' ? zhCnMessages : englishMessages
+    );
+    const messages = await loadMessagesWithCatalogLoader('zh-CN', loadCatalog);
 
     expect(messages.shared).toBe(zhCnMessages.shared);
     expect(messages.englishOnly).toBe(englishMessages.englishOnly);
+    expect(loadCatalog).toHaveBeenCalledWith('en');
+    expect(loadCatalog).toHaveBeenCalledWith('zh-CN');
   });
 
   it('returns English messages for unsupported locale (with warning)', async () => {
     const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-    const loadMessages = await loadMessagesWithMockedCatalogs();
-    const messages = await loadMessages('xx');
+    const loadCatalog = vi.fn(async (locale: string) => {
+      if (locale === 'xx') {
+        throw new Error('missing catalog');
+      }
+      return englishMessages;
+    });
+    const messages = await loadMessagesWithCatalogLoader('xx', loadCatalog);
+
     expect(messages).toEqual(englishMessages);
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index 098ae1872c54..e5d9846839ab 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -90,7 +90,7 @@ export const currentLocale = resolvedLocale.locale;
 /** Base language for loading message catalogs (e.g. "en"). */
 export const currentMessageLocale = resolvedLocale.messageLocale;
 
-async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
+export async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
   const mod = await import(`./compiled/${locale}.json`);
   return (mod.default ?? mod) as Record<string, string>;
 }
@@ -102,7 +102,14 @@ async function loadCompiledMessages(locale: string): Promise<Record<string, stri
  * triggering missing translation warnings for every message.
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
-  const englishMessages = await loadCompiledMessages('en');
+  return loadMessagesWithCatalogLoader(locale, loadCompiledMessages);
+}
+
+export async function loadMessagesWithCatalogLoader(
+  locale: string,
+  loadCatalog: (locale: string) => Promise<Record<string, string>>
+): Promise<Record<string, string>> {
+  const englishMessages = await loadCatalog('en');
 
   if (locale === 'en') {
     return englishMessages;
@@ -110,7 +117,7 @@ export async function loadMessages(locale: string): Promise<Record<string, strin
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
-    const messages = await loadCompiledMessages(locale);
+    const messages = await loadCatalog(locale);
     return {
       ...englishMessages,
       ...messages,

From 1218484f8e1fc5b4ebf2ccdad8ec58e813f63136 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 14:41:47 +1000
Subject: [PATCH 4/9] address comments

---
 ui/desktop/src/i18n/i18n.test.ts | 14 ++++++++++++++
 ui/desktop/src/i18n/index.ts     | 13 +++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 70b6ecdec40f..012f3a3b6061 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -105,4 +105,18 @@ describe('loadMessages', () => {
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
   });
+
+  it('falls back to default messages when the English catalog is unavailable', async () => {
+    const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const loadCatalog = vi.fn(async () => {
+      throw new Error('missing catalog');
+    });
+    const messages = await loadMessagesWithCatalogLoader('en', loadCatalog);
+
+    expect(messages).toEqual({});
+    expect(warnSpy).toHaveBeenCalledWith(
+      '[i18n] No English fallback catalog found; missing messages will use source defaultMessage values.'
+    );
+    warnSpy.mockRestore();
+  });
 });
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index e5d9846839ab..cd3411731dd0 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -109,7 +109,16 @@ export async function loadMessagesWithCatalogLoader(
   locale: string,
   loadCatalog: (locale: string) => Promise<Record<string, string>>
 ): Promise<Record<string, string>> {
-  const englishMessages = await loadCatalog('en');
+  let englishMessages: Record<string, string>;
+
+  try {
+    englishMessages = await loadCatalog('en');
+  } catch {
+    console.warn(
+      '[i18n] No English fallback catalog found; missing messages will use source defaultMessage values.'
+    );
+    englishMessages = {};
+  }
 
   if (locale === 'en') {
     return englishMessages;
@@ -124,7 +133,7 @@ export async function loadMessagesWithCatalogLoader(
     };
   } catch {
     console.warn(
-      `[i18n] No message catalog found for locale "${locale}", falling back to English.`
+      `[i18n] No message catalog found for locale "${locale}"; using fallback messages.`
     );
     return englishMessages;
   }

From 27bc22a4e51d9ec319c6f1f91738016910dce3f8 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 20:35:22 +1000
Subject: [PATCH 5/9] Revert "address comments"

This reverts commit 1218484f8e1fc5b4ebf2ccdad8ec58e813f63136.
---
 ui/desktop/src/i18n/i18n.test.ts | 14 --------------
 ui/desktop/src/i18n/index.ts     | 13 ++-----------
 2 files changed, 2 insertions(+), 25 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 012f3a3b6061..70b6ecdec40f 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -105,18 +105,4 @@ describe('loadMessages', () => {
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
   });
-
-  it('falls back to default messages when the English catalog is unavailable', async () => {
-    const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-    const loadCatalog = vi.fn(async () => {
-      throw new Error('missing catalog');
-    });
-    const messages = await loadMessagesWithCatalogLoader('en', loadCatalog);
-
-    expect(messages).toEqual({});
-    expect(warnSpy).toHaveBeenCalledWith(
-      '[i18n] No English fallback catalog found; missing messages will use source defaultMessage values.'
-    );
-    warnSpy.mockRestore();
-  });
 });
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index cd3411731dd0..e5d9846839ab 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -109,16 +109,7 @@ export async function loadMessagesWithCatalogLoader(
   locale: string,
   loadCatalog: (locale: string) => Promise<Record<string, string>>
 ): Promise<Record<string, string>> {
-  let englishMessages: Record<string, string>;
-
-  try {
-    englishMessages = await loadCatalog('en');
-  } catch {
-    console.warn(
-      '[i18n] No English fallback catalog found; missing messages will use source defaultMessage values.'
-    );
-    englishMessages = {};
-  }
+  const englishMessages = await loadCatalog('en');
 
   if (locale === 'en') {
     return englishMessages;
@@ -133,7 +124,7 @@ export async function loadMessagesWithCatalogLoader(
     };
   } catch {
     console.warn(
-      `[i18n] No message catalog found for locale "${locale}"; using fallback messages.`
+      `[i18n] No message catalog found for locale "${locale}", falling back to English.`
     );
     return englishMessages;
   }

From a31ff32cde7caae4715d39bb3ffb96cedf4751fc Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 20:35:30 +1000
Subject: [PATCH 6/9] Revert "fixed tests"

This reverts commit d58242c3c5f42393e9019eadbe864fe3fd193b7c.
---
 ui/desktop/src/i18n/i18n.test.ts | 42 +++++++++++++++++---------------
 ui/desktop/src/i18n/index.ts     | 13 +++-------
 2 files changed, 25 insertions(+), 30 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 70b6ecdec40f..95c45459fbc8 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
-import { getLocale, loadMessagesWithCatalogLoader } from './index';
+import { getLocale } from './index';
 
 const englishMessages = {
   shared: 'English shared message',
@@ -70,37 +70,39 @@ describe('getLocale', () => {
 });
 
 describe('loadMessages', () => {
-  it('returns compiled English messages for English locale', async () => {
-    const loadCatalog = vi.fn().mockResolvedValue(englishMessages);
-    const messages = await loadMessagesWithCatalogLoader('en', loadCatalog);
+  afterEach(() => {
+    vi.doUnmock('./compiled/en.json');
+    vi.doUnmock('./compiled/zh-CN.json');
+    vi.resetModules();
+  });
+
+  async function loadMessagesWithMockedCatalogs() {
+    vi.resetModules();
+    vi.doMock('./compiled/en.json', () => ({ default: englishMessages }));
+    vi.doMock('./compiled/zh-CN.json', () => ({ default: zhCnMessages }));
 
+    const { loadMessages } = await import('./index');
+    return loadMessages;
+  }
+
+  it('returns compiled English messages for English locale', async () => {
+    const loadMessages = await loadMessagesWithMockedCatalogs();
+    const messages = await loadMessages('en');
     expect(messages).toEqual(englishMessages);
-    expect(loadCatalog).toHaveBeenCalledOnce();
-    expect(loadCatalog).toHaveBeenCalledWith('en');
   });
 
   it('merges locale messages over English fallback messages', async () => {
-    const loadCatalog = vi.fn(async (locale: string) =>
-      locale === 'zh-CN' ? zhCnMessages : englishMessages
-    );
-    const messages = await loadMessagesWithCatalogLoader('zh-CN', loadCatalog);
+    const loadMessages = await loadMessagesWithMockedCatalogs();
+    const messages = await loadMessages('zh-CN');
 
     expect(messages.shared).toBe(zhCnMessages.shared);
     expect(messages.englishOnly).toBe(englishMessages.englishOnly);
-    expect(loadCatalog).toHaveBeenCalledWith('en');
-    expect(loadCatalog).toHaveBeenCalledWith('zh-CN');
   });
 
   it('returns English messages for unsupported locale (with warning)', async () => {
     const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-    const loadCatalog = vi.fn(async (locale: string) => {
-      if (locale === 'xx') {
-        throw new Error('missing catalog');
-      }
-      return englishMessages;
-    });
-    const messages = await loadMessagesWithCatalogLoader('xx', loadCatalog);
-
+    const loadMessages = await loadMessagesWithMockedCatalogs();
+    const messages = await loadMessages('xx');
     expect(messages).toEqual(englishMessages);
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index e5d9846839ab..098ae1872c54 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -90,7 +90,7 @@ export const currentLocale = resolvedLocale.locale;
 /** Base language for loading message catalogs (e.g. "en"). */
 export const currentMessageLocale = resolvedLocale.messageLocale;
 
-export async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
+async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
   const mod = await import(`./compiled/${locale}.json`);
   return (mod.default ?? mod) as Record<string, string>;
 }
@@ -102,14 +102,7 @@ export async function loadCompiledMessages(locale: string): Promise<Record<strin
  * triggering missing translation warnings for every message.
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
-  return loadMessagesWithCatalogLoader(locale, loadCompiledMessages);
-}
-
-export async function loadMessagesWithCatalogLoader(
-  locale: string,
-  loadCatalog: (locale: string) => Promise<Record<string, string>>
-): Promise<Record<string, string>> {
-  const englishMessages = await loadCatalog('en');
+  const englishMessages = await loadCompiledMessages('en');
 
   if (locale === 'en') {
     return englishMessages;
@@ -117,7 +110,7 @@ export async function loadMessagesWithCatalogLoader(
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
-    const messages = await loadCatalog(locale);
+    const messages = await loadCompiledMessages(locale);
     return {
       ...englishMessages,
       ...messages,

From f052b9a012f12fb656a441c89b3ab94833966d7e Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 20:35:39 +1000
Subject: [PATCH 7/9] Revert "fixed typecheck"

This reverts commit eb2c2bf8735f62e4df2b706f72b049c7640de946.
---
 ui/desktop/src/i18n/index.ts | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index 098ae1872c54..bc2043971e2a 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -90,11 +90,6 @@ export const currentLocale = resolvedLocale.locale;
 /** Base language for loading message catalogs (e.g. "en"). */
 export const currentMessageLocale = resolvedLocale.messageLocale;
 
-async function loadCompiledMessages(locale: string): Promise<Record<string, string>> {
-  const mod = await import(`./compiled/${locale}.json`);
-  return (mod.default ?? mod) as Record<string, string>;
-}
-
 /**
  * Load compiled messages for a given locale.
  * English messages are always loaded as the fallback catalog so regional
@@ -102,7 +97,8 @@ async function loadCompiledMessages(locale: string): Promise<Record<string, stri
  * triggering missing translation warnings for every message.
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
-  const englishMessages = await loadCompiledMessages('en');
+  const englishMod = await import('./compiled/en.json');
+  const englishMessages = englishMod.default ?? englishMod;
 
   if (locale === 'en') {
     return englishMessages;
@@ -110,10 +106,10 @@ export async function loadMessages(locale: string): Promise<Record<string, strin
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
-    const messages = await loadCompiledMessages(locale);
+    const mod = await import(`./compiled/${locale}.json`);
     return {
       ...englishMessages,
-      ...messages,
+      ...(mod.default ?? mod),
     };
   } catch {
     console.warn(

From e63d60fb01754531972f7181d1ce10170ed7f9c2 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 20:36:01 +1000
Subject: [PATCH 8/9] Revert "silence MISSING_TRANSLATION warnings for fallback
 locales"

This reverts commit b5b945fc2ceddaf8fca3ded8ab55b3830286cb66.
---
 ui/desktop/src/i18n/i18n.test.ts | 42 ++++----------------------------
 ui/desktop/src/i18n/index.ts     | 17 ++++---------
 2 files changed, 10 insertions(+), 49 deletions(-)

diff --git a/ui/desktop/src/i18n/i18n.test.ts b/ui/desktop/src/i18n/i18n.test.ts
index 95c45459fbc8..808883e32e39 100644
--- a/ui/desktop/src/i18n/i18n.test.ts
+++ b/ui/desktop/src/i18n/i18n.test.ts
@@ -1,15 +1,6 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { getLocale } from './index';
 
-const englishMessages = {
-  shared: 'English shared message',
-  englishOnly: 'English fallback message',
-};
-
-const zhCnMessages = {
-  shared: 'Chinese shared message',
-};
-
 // Helper to mock window.appConfig for tests
 function mockAppConfig(values: Record<string, unknown>) {
   (window as unknown as Record<string, unknown>).appConfig = {
@@ -70,40 +61,17 @@ describe('getLocale', () => {
 });
 
 describe('loadMessages', () => {
-  afterEach(() => {
-    vi.doUnmock('./compiled/en.json');
-    vi.doUnmock('./compiled/zh-CN.json');
-    vi.resetModules();
-  });
-
-  async function loadMessagesWithMockedCatalogs() {
-    vi.resetModules();
-    vi.doMock('./compiled/en.json', () => ({ default: englishMessages }));
-    vi.doMock('./compiled/zh-CN.json', () => ({ default: zhCnMessages }));
-
+  it('returns empty object for English locale', async () => {
     const { loadMessages } = await import('./index');
-    return loadMessages;
-  }
-
-  it('returns compiled English messages for English locale', async () => {
-    const loadMessages = await loadMessagesWithMockedCatalogs();
     const messages = await loadMessages('en');
-    expect(messages).toEqual(englishMessages);
+    expect(messages).toEqual({});
   });
 
-  it('merges locale messages over English fallback messages', async () => {
-    const loadMessages = await loadMessagesWithMockedCatalogs();
-    const messages = await loadMessages('zh-CN');
-
-    expect(messages.shared).toBe(zhCnMessages.shared);
-    expect(messages.englishOnly).toBe(englishMessages.englishOnly);
-  });
-
-  it('returns English messages for unsupported locale (with warning)', async () => {
+  it('returns empty object for unsupported locale (with warning)', async () => {
     const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
-    const loadMessages = await loadMessagesWithMockedCatalogs();
+    const { loadMessages } = await import('./index');
     const messages = await loadMessages('xx');
-    expect(messages).toEqual(englishMessages);
+    expect(messages).toEqual({});
     expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining('No message catalog found'));
     warnSpy.mockRestore();
   });
diff --git a/ui/desktop/src/i18n/index.ts b/ui/desktop/src/i18n/index.ts
index bc2043971e2a..07a6d23c828d 100644
--- a/ui/desktop/src/i18n/index.ts
+++ b/ui/desktop/src/i18n/index.ts
@@ -92,29 +92,22 @@ export const currentMessageLocale = resolvedLocale.messageLocale;
 
 /**
  * Load compiled messages for a given locale.
- * English messages are always loaded as the fallback catalog so regional
- * English locales can keep their locale for date/number formatting without
- * triggering missing translation warnings for every message.
+ * Returns an empty object for English (react-intl uses defaultMessage as fallback).
  */
 export async function loadMessages(locale: string): Promise<Record<string, string>> {
-  const englishMod = await import('./compiled/en.json');
-  const englishMessages = englishMod.default ?? englishMod;
-
   if (locale === 'en') {
-    return englishMessages;
+    // English strings live in source code as defaultMessage — no catalog needed.
+    return {};
   }
 
   try {
     // Dynamic import so compiled translation bundles are code-split.
     const mod = await import(`./compiled/${locale}.json`);
-    return {
-      ...englishMessages,
-      ...(mod.default ?? mod),
-    };
+    return mod.default ?? mod;
   } catch {
     console.warn(
       `[i18n] No message catalog found for locale "${locale}", falling back to English.`
     );
-    return englishMessages;
+    return {};
   }
 }

From f1032c115b683c771266b55c0d45e407cc433623 Mon Sep 17 00:00:00 2001
From: Lifei Zhou <lifei@squareup.com>
Date: Mon, 18 May 2026 20:51:17 +1000
Subject: [PATCH 9/9] suppressed excessive warning

---
 ui/desktop/src/renderer.tsx | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/ui/desktop/src/renderer.tsx b/ui/desktop/src/renderer.tsx
index c9df7f1ea991..3e6533188a15 100644
--- a/ui/desktop/src/renderer.tsx
+++ b/ui/desktop/src/renderer.tsx
@@ -17,6 +17,20 @@ const App = lazy(() => import('./App'));
 
 const TELEMETRY_CONFIG_KEY = 'GOOSE_TELEMETRY_ENABLED';
 
+let warnedFallbackLocale = false;
+function handleIntlError(err: { code: string; message?: string }) {
+  if (err.code === 'MISSING_TRANSLATION' && currentLocale !== currentMessageLocale) {
+    if (!warnedFallbackLocale) {
+      warnedFallbackLocale = true;
+      console.warn(
+        `[i18n] Locale "${currentLocale}" has no translations; falling back to "${currentMessageLocale}".`
+      );
+    }
+    return;
+  }
+  console.error(err);
+}
+
 (async () => {
   // Check if we're in the launcher view (doesn't need goosed connection)
   const isLauncher = window.location.hash === '#/launcher';
@@ -50,7 +64,12 @@ const TELEMETRY_CONFIG_KEY = 'GOOSE_TELEMETRY_ENABLED';
 
   ReactDOM.createRoot(document.getElementById('root')!).render(
     <React.StrictMode>
-      <IntlProvider locale={currentLocale} defaultLocale="en" messages={messages}>
+      <IntlProvider
+        locale={currentLocale}
+        defaultLocale="en"
+        messages={messages}
+        onError={handleIntlError}
+      >
         <Suspense fallback={SuspenseLoader()}>
           <ConfigProvider>
             <ErrorBoundary>