Pin the UI locale to the language setting and add theme + language selectors with a dark palette

src/main/app/ipc-handlers.ts

@@ -1,4 +1,4 @@
-import { dialog, ipcMain, shell, type BrowserWindow } from "electron";
+import { app, dialog, ipcMain, shell, type BrowserWindow } from "electron";
 import type { DatabaseConnection } from "../database/connection";
 import { IPC_CHANNELS } from "../../shared/ipc";
 import { fail, ok, type DesktopResult } from "../../shared/result";
@@ -107,6 +107,19 @@ export function registerIpcHandlers(deps: IpcDeps): void {
 
   ipcMain.handle(IPC_CHANNELS.createOrganization, (_event, input) => mutate(() => organization.createOrganization(input)));
   ipcMain.handle(IPC_CHANNELS.setActiveOrganization, (_event, input) => mutate(() => organization.setActiveOrganization(input.orgId)));
+  ipcMain.handle(IPC_CHANNELS.setUiPreferences, (_event, input) => {
+    const before = snapshot.load().uiPreferences.language;
+    const result = mutate(() => organization.updateUiPreferences(input));
+    if (result.ok && result.data.uiPreferences.language !== before) {
+      // Chromium's locale is fixed at launch; a language change needs a
+      // fresh process to take effect.
+      setTimeout(() => {
+        app.relaunch();
+        app.quit();
+      }, 150);
+    }
+    return result;
+  });
   ipcMain.handle(IPC_CHANNELS.deleteOrganization, (_event, input) => mutate(() => organization.deleteOrganization(input.orgId)));
   ipcMain.handle(IPC_CHANNELS.createAgent, (_event, input) => mutate(() => organization.createAgent(input)));
   ipcMain.handle(IPC_CHANNELS.updateAgent, (_event, input) => mutate(() => organization.updateAgent(input)));

src/main/database/migrations/048-ui-preferences.ts

@@ -0,0 +1,10 @@
+/**
+ * App-level UI preferences on the single app_state row. Theme drives the
+ * renderer palette; language pins Chromium's UI locale (form-control strings
+ * were following the OS locale and leaking Chinese into the English UI, so
+ * the default is English rather than system).
+ */
+export const uiPreferencesSchema = `
+  alter table app_state add column theme text not null default 'system';
+  alter table app_state add column language text not null default 'en';
+`;

src/main/database/schema.ts

@@ -46,6 +46,7 @@ import { mentionWakeStateSchema } from "./migrations/044-mention-wake-state";
 import { connectorGrantsSchema } from "./migrations/045-connector-grants";
 import { composioKeyPurgeSchema } from "./migrations/046-composio-key-purge";
 import { authConfigPurgeSchema } from "./migrations/047-auth-config-purge";
+import { uiPreferencesSchema } from "./migrations/048-ui-preferences";
 
 interface Migration {
   version: number;
@@ -101,6 +102,7 @@ const MIGRATIONS: Migration[] = [
   { version: 45, name: "connector_grants", sql: connectorGrantsSchema },
   { version: 46, name: "composio_key_purge", sql: composioKeyPurgeSchema },
   { version: 47, name: "auth_config_purge", sql: authConfigPurgeSchema },
+  { version: 48, name: "ui_preferences", sql: uiPreferencesSchema },
 ];
 
 const SCHEMA_VERSION = MIGRATIONS[MIGRATIONS.length - 1].version;

src/main/index.ts

@@ -18,9 +18,14 @@ const __dirname = dirname(fileURLToPath(import.meta.url));
 if (!app.requestSingleInstanceLock()) {
   app.quit();
 } else {
+  const profileDir = process.env.AGENTCOMPANY_NEW_PROFILE_DIR ?? join(app.getPath("userData"), "profile");
+  // The database opens before ready: Chromium's UI locale (form-control
+  // strings, date formatting) is only settable pre-ready, and it follows the
+  // stored language preference instead of the OS locale.
+  const connection = new DatabaseConnection(join(profileDir, "agentcompany.db"));
+  app.commandLine.appendSwitch("lang", storedLanguage(connection.db) === "zh" ? "zh-CN" : "en-US");
+
   app.whenReady().then(() => {
-    const profileDir = process.env.AGENTCOMPANY_NEW_PROFILE_DIR ?? join(app.getPath("userData"), "profile");
-    const connection = new DatabaseConnection(join(profileDir, "agentcompany.db"));
     connection.transaction(() => recoverInterruptedWork(connection.db));
     const win = createMainWindow({
       preloadPath: join(__dirname, "../preload/index.js"),
@@ -60,6 +65,11 @@ if (!app.requestSingleInstanceLock()) {
   });
 }
 
+function storedLanguage(db: DatabaseSync): string {
+  const row = db.prepare("select language from app_state where id = 1").get() as { language: string } | undefined;
+  return row?.language ?? "en";
+}
+
 /**
  * Loads the on-disk skill library for every organization at startup. One
  * organization's failure (a broken workspace path, say) must not block the

src/main/services/organization-service.ts

@@ -47,6 +47,18 @@ export class OrganizationService {
     });
   }
 
+  updateUiPreferences(input: { theme?: "system" | "light" | "dark"; language?: "en" | "zh" }): void {
+    const current = this.db.prepare("select theme, language from app_state where id = 1")
+      .get() as { theme: string; language: string } | undefined;
+    const theme = input.theme ?? current?.theme ?? "system";
+    const language = input.language ?? current?.language ?? "en";
+    this.db.prepare(`
+      insert into app_state(id, active_org_id, theme, language, updated_at)
+      values (1, null, ?, ?, ?)
+      on conflict(id) do update set theme = excluded.theme, language = excluded.language, updated_at = excluded.updated_at
+    `).run(theme, language, new Date().toISOString());
+  }
+
   deleteOrganization(orgId: string): void {
     const row = this.db.prepare("select id from organizations where id = ?")
       .get(orgId) as { id: string } | undefined;

src/main/services/snapshot-service.ts

@@ -87,6 +87,7 @@ export class SnapshotService {
 
     return {
       activeOrgId,
+      uiPreferences: this.resolveUiPreferences(),
       organizations,
       employees: list(this.db, "employees", "created_at asc"),
       agents,
@@ -178,6 +179,14 @@ export class SnapshotService {
     if (stored && known.includes(stored)) return stored;
     return known[0] ?? null;
   }
+
+  private resolveUiPreferences(): AppSnapshot["uiPreferences"] {
+    const row = this.db.prepare("select theme, language from app_state where id = 1")
+      .get() as { theme: string; language: string } | undefined;
+    const theme = row?.theme === "light" || row?.theme === "dark" ? row.theme : "system";
+    const language = row?.language === "zh" ? "zh" : "en";
+    return { theme, language };
+  }
 }
 
 function buildProviderRateLimits(