@@ -0,0 +1,14 @@
+---
+'@objectstack/rest': patch
+---
+
+fix(rest): a boolean cell in the list export is written in the caller's language (#24945)
+
+Clause-②: no
+
+`GET /api/v1/data/:object/export` (Display → Export as CSV / XLSX / JSON) wrote every boolean or toggle cell as `是` or `否`, whatever the caller read. The header row of the same file follows the caller's locale, so an English caller got "Converted" and "Do Not Call" over Chinese cells.
+
+- **Now.** A boolean or toggle cell is written in the words the import template already uses for the caller's locale: `yes` / `no`, or `是` / `否` for a `zh*` locale. The locale is the one the header row is translated to: `Accept-Language`, then `?locale=`, then the deployment's default locale. The header and the cells always read one language. This applies to csv, xlsx and json.
+- **No locale at all.** When the request names no locale and the deployment declares no default, the cells read `yes` / `no`, the same words the import template writes then.
+- **Re-import.** A file exported in either language re-imports its boolean column: the importer reads `yes` / `no` and `是` / `否`.
+- **Unchanged.** No query parameter, header, column set or payload shape moves. Only the text of a boolean cell changes, and a Chinese caller's file is byte-for-byte what it was.
@@ -68,7 +68,7 @@ import {
     type ExportCellMeta,
 } from './export-format.js';
 import { importControlOptOutRefusal, prepareImportRequest } from './import-prepare.js';
-import { readTemplateMode, templateFieldDefs } from './import-template.js';
+import { readTemplateMode, templateFieldDefs, templateText } from './import-template.js';
 import { refuseRepeatedQueryParams } from './query-multiplicity.js';
 import { refuseUnknownQueryParams } from './query-allowlist.js';
 import { handleRouteError, logUnexpectedRouteError, mapDataError, nestedRefusalEnvelope } from './error-response.js';
@@ -200,6 +200,8 @@ export interface DataActionRouteHost {
     translateMetaItem: RestServer['translateMetaItem'];
     resolveMessageTranslator: RestServer['resolveMessageTranslator'];
     resolveSecurityService: RestServer['resolveSecurityService'];
+    resolveI18nService: RestServer['resolveI18nService'];
+    extractLocale: RestServer['extractLocale'];
     answerImportTemplate: RestServer['answerImportTemplate'];
 }
 
@@ -884,8 +886,15 @@ export function registerDataActionEndpoints(this: DataActionRouteHost, basePath:
     //
     // Values are formatted for readability from the object schema: lookup /
     // user fields resolve to a name (via injected $expand), select fields to
-    // their option label, booleans to 是/否, dates to YYYY-MM-DD. When the
-    // schema is unavailable the raw stored values stream through unchanged.
+    // their option label, booleans to the caller's yes / no words, dates to
+    // YYYY-MM-DD. When the schema is unavailable the raw stored values stream
+    // through unchanged.
+    //
+    // [#24945] Boolean / toggle cells are written in the language of the
+    // header row: `templateText(locale).booleanWords` (yes / no, or 是 / 否 for
+    // a `zh*` locale), for the locale the header labels are translated to
+    // (`Accept-Language`, then `?locale=`, then the i18n service's default).
+    // The importer reads both languages back, so the file re-imports.
     //
     // [#8373] `datetime` cells render in the caller's BUSINESS timezone
     // (`ExecutionContext.timezone`), so the file agrees with the screen;
@@ -1084,7 +1093,7 @@ export function registerDataActionEndpoints(this: DataActionRouteHost, basePath:
                 const fieldsExplicit = !!fields && fields.length > 0;
 
                 // Field metadata drives readable formatting (lookup names, select
-                // labels, 是/否, formatted dates) and the $expand that resolves
+                // labels, yes / no words, formatted dates) and the $expand that resolves
                 // references. Best-effort: when the schema is unavailable the export
                 // falls back to raw values, byte-identical to the un-formatted path.
                 let metaMap = new Map<string, ExportCellMeta>();
@@ -1111,13 +1120,23 @@ export function registerDataActionEndpoints(this: DataActionRouteHost, basePath:
                     }
                     return schema;
                 };
+                // [#24945] The file's language, read once for both of its halves:
+                // the header labels below are translated with THIS i18n service,
+                // which `extractLocale` also reads the request's locale from (its
+                // default locale is the last fallback), and the boolean cells are
+                // written in the words of the same locale — the pair the import
+                // template offers (`templateText`, `./import-template.ts`). One
+                // service and one locale, so the header and the cells cannot read
+                // two different languages.
+                const i18n = await this.resolveI18nService(environmentId, req).catch(() => undefined);
+                const booleanWords = templateText(this.extractLocale(req, i18n)).booleanWords;
                 try {
                     let schema: any = await readObjectSchema(objectName);
                     // Localize field labels to the request locale (Accept-Language /
                     // `?locale=`) the same way the metadata endpoints do, so the
                     // export header row matches the UI column headers instead of
                     // leaking the raw, untranslated `field.label` values.
-                    schema = await this.translateMetaItem(req, 'object', environmentId, schema);
+                    schema = await this.translateMetaItem(req, 'object', environmentId, schema, i18n);
                     if (typeof schema?.label === 'string' && schema.label.length > 0) {
                         objectLabel = schema.label;
                     }
@@ -1291,15 +1310,15 @@ export function registerDataActionEndpoints(this: DataActionRouteHost, basePath:
                     }
 
                     if (format === 'csv') {
-                        const text = rowsToCsv(fields ?? [], rows, firstChunk && includeHeader, metaMap, timezone);
+                        const text = rowsToCsv(fields ?? [], rows, firstChunk && includeHeader, metaMap, timezone, booleanWords);
                         res.write(text);
                     } else if (format === 'xlsx') {
                         if (firstChunk && includeHeader) {
                             xlsx!.ws.addRow((fields ?? []).map((f) => headerLabel(f, metaMap))).commit();
                         }
                         const cols = fields ?? [];
                         for (const row of rows) {
-                            const r = xlsx!.ws.addRow(formatRowCells(row, cols, metaMap, timezone));
+                            const r = xlsx!.ws.addRow(formatRowCells(row, cols, metaMap, timezone, booleanWords));
                             if (styled) {
                                 cols.forEach((f, i) => {
                                     const argb = cellFontColor(row?.[f], metaMap.get(f));
@@ -1320,7 +1339,7 @@ export function registerDataActionEndpoints(this: DataActionRouteHost, basePath:
                         for (let i = 0; i < rows.length; i++) {
                             const prefix = (firstChunk && i === 0) ? '' : ',';
                             const row = fieldsExplicit ? pickExportKeys(rows[i], fields!) : rows[i];
-                            res.write(prefix + JSON.stringify(formatRowForJson(row, metaMap, timezone)));
+                            res.write(prefix + JSON.stringify(formatRowForJson(row, metaMap, timezone, booleanWords)));
                         }
                     }
                     firstChunk = false;
 
@@ -0,0 +1,256 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#24945] A boolean or toggle cell of `GET /data/:object/export` is written in
+ * the caller's language — the same language as the header row of that file.
+ *
+ * The export formatter used to write the literal `是` / `否` for every boolean
+ * cell, whatever the caller read: an `Accept-Language: en-US` caller got the
+ * English header row ("Converted", "Do Not Call") over Chinese cells. The words
+ * now come from the one table the import template already offers them from,
+ * `templateText(locale).booleanWords` (`import-template.ts`), for the locale the
+ * route resolves for its header labels — the request's i18n service read once
+ * and handed to both the header translation and the words, so the two halves of
+ * the file cannot read two different locales.
+ *
+ * The file must stay importable in either language: the last block exports in
+ * each language and re-imports the file through the real import route into a
+ * fresh store, so the boolean column has to read back as the values it left as.
+ *
+ * Driven end to end: the real export and import routes, a real ObjectQL engine
+ * and protocol, and a real sqlite `:memory:` driver (the harness of
+ * `export-integration.test.ts`).
+ */
+
+import { describe, it, expect, afterEach } from 'vitest';
+import { ObjectQL } from '@objectstack/objectql';
+import { SqlDriver } from '@objectstack/driver-sql';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
+import { SysMetadataAuditObject, SysMetadataCommitObject, SysMetadataHistoryObject, SysMetadataObject } from '@objectstack/metadata-core';
+import { RestServer } from './rest-server';
+import { templateText } from './import-template.js';
+import { loadXlsxWorkbook } from './xlsx-test-loader.js';
+
+const liveEngines: ObjectQL[] = [];
+afterEach(async () => {
+  while (liveEngines.length) {
+    try { await liveEngines.pop()?.destroy(); } catch { /* noop */ }
+  }
+});
+
+/** Authored in English; the zh-CN bundle below translates every label. */
+const LEAD = {
+  name: 'lead',
+  label: 'Lead',
+  systemFields: false,
+  fields: {
+    id: { name: 'id', type: 'text' as const, primaryKey: true, label: 'ID' },
+    full_name: { name: 'full_name', type: 'text' as const, label: 'Full Name' },
+    is_converted: { name: 'is_converted', type: 'boolean' as const, label: 'Converted' },
+    do_not_call: { name: 'do_not_call', type: 'toggle' as const, label: 'Do Not Call' },
+  },
+};
+
+const BUNDLE: Record<string, unknown> = {
+  'zh-CN': {
+    objects: {
+      lead: {
+        label: '线索',
+        fields: {
+          id: { label: '编号' },
+          full_name: { label: '姓名' },
+          is_converted: { label: '已转化' },
+          do_not_call: { label: '请勿致电' },
+        },
+      },
+    },
+  },
+};
+
+/** An i18n service of the shape `@objectstack/service-i18n` serves. */
+function i18nService(defaultLocale?: string) {
+  return {
+    getLocales: () => Object.keys(BUNDLE),
+    getTranslations: (locale: string) => BUNDLE[locale],
+    ...(defaultLocale ? { getDefaultLocale: () => defaultLocale } : {}),
+  };
+}
+
+const ROWS = [
+  { id: '1', full_name: 'Wren Halvorsen', is_converted: true, do_not_call: false },
+  { id: '2', full_name: 'Tomas Okafor', is_converted: false, do_not_call: true },
+];
+
+const EN_HEADER = ['ID', 'Full Name', 'Converted', 'Do Not Call'];
+const ZH_HEADER = ['编号', '姓名', '已转化', '请勿致电'];
+const EN_CELLS = [['1', 'Wren Halvorsen', 'yes', 'no'], ['2', 'Tomas Okafor', 'no', 'yes']];
+const ZH_CELLS = [['1', 'Wren Halvorsen', '是', '否'], ['2', 'Tomas Okafor', '否', '是']];
+
+function createMockServer() {
+  const noop = () => {};
+  return { get: noop, post: noop, put: noop, delete: noop, patch: noop, use: noop, listen: async () => {}, close: async () => {} };
+}
+
+function makeRes() {
+  const chunks: Buffer[] = [];
+  const headers: Record<string, string> = {};
+  const res: any = {
+    write: (c: any) => { chunks.push(Buffer.isBuffer(c) ? c : Buffer.from(String(c))); return true; },
+    end: () => {},
+    header: (n: string, v: string) => { headers[n] = v; return res; },
+    status: (code: number) => { res._status = code; return res; },
+    json: (body: any) => { res._json = body; return res; },
+  };
+  return { res, headers, text: () => Buffer.concat(chunks).toString('utf8'), buffer: () => Buffer.concat(chunks) };
+}
+
+/**
+ * Boot one engine + REST server. `i18n` is the request's i18n service:
+ * `null` leaves the server's own resolution in place (none in this harness).
+ */
+async function boot(i18n: unknown, rows: ReadonlyArray<Record<string, unknown>> = ROWS) {
+  const engine = new ObjectQL();
+  liveEngines.push(engine);
+  engine.registerDriver(new SqlDriver({
+    client: 'better-sqlite3',
+    connection: { filename: ':memory:' },
+    useNullAsDefault: true,
+  }), true);
+  await engine.init();
+  engine.registry.registerObject(LEAD as any);
+  await engine.syncSchemas();
+  for (const row of rows) await engine.insert('lead', { ...row });
+  for (const o of [SysMetadataObject, SysMetadataHistoryObject, SysMetadataAuditObject, SysMetadataCommitObject]) {
+    if (!engine.registry.getObject(o.name)) engine.registry.registerObject(o as any);
+  }
+  const protocol = new ObjectStackProtocolImplementation(engine as any);
+  const rest = new RestServer(createMockServer() as any, protocol as any, { api: { requireAuth: false } } as any);
+  (rest as any).resolveExecCtx = async () => ({ userId: 'test-user' });
+  if (i18n !== null) (rest as any).resolveI18nService = async () => i18n;
+  rest.registerRoutes();
+  const routes = rest.getRoutes();
+  const exportRoute = routes.find((r: any) => r.method === 'GET' && r.path === '/api/v1/data/:object/export')!;
+  const importRoute = routes.find((r: any) => r.method === 'POST' && r.path === '/api/v1/data/:object/import')!;
+  return { engine, exportRoute, importRoute };
+}
+
+async function exportFile(
+  route: any,
+  format: 'csv' | 'xlsx' | 'json',
+  opts: { acceptLanguage?: string; locale?: string } = {},
+) {
+  const { res, text, buffer } = makeRes();
+  await route.handler({
+    params: { object: 'lead' },
+    query: { format, ...(opts.locale ? { locale: opts.locale } : {}) },
+    headers: opts.acceptLanguage ? { 'accept-language': opts.acceptLanguage } : {},
+  } as any, res);
+  return { text, buffer };
+}
+
+function csvRows(text: string): string[][] {
+  return text.split('\r\n').filter((l) => l.length > 0).map((l) => l.split(','));
+}
+
+async function xlsxRows(buffer: Buffer): Promise<string[][]> {
+  const ws = (await loadXlsxWorkbook(buffer)).worksheets[0];
+  const out: string[][] = [];
+  ws.eachRow((row) => { out.push((row.values as unknown[]).slice(1).map((v) => String(v))); });
+  return out;
+}
+
+describe('export: a boolean cell speaks the language of its header row', () => {
+  it('an English caller gets yes / no under the English header (csv)', async () => {
+    const { exportRoute } = await boot(i18nService('en'));
+    const rows = csvRows((await exportFile(exportRoute, 'csv', { acceptLanguage: 'en-US' })).text());
+    expect(rows).toEqual([EN_HEADER, ...EN_CELLS]);
+  });
+
+  it('a Chinese caller gets 是 / 否 under the Chinese header (csv)', async () => {
+    const { exportRoute } = await boot(i18nService('en'));
+    const rows = csvRows((await exportFile(exportRoute, 'csv', { acceptLanguage: 'zh-CN' })).text());
+    expect(rows).toEqual([ZH_HEADER, ...ZH_CELLS]);
+  });
+
+  it('xlsx writes the same words as csv, per caller', async () => {
+    const { exportRoute } = await boot(i18nService('en'));
+    expect(await xlsxRows((await exportFile(exportRoute, 'xlsx', { acceptLanguage: 'en-US' })).buffer()))
+      .toEqual([EN_HEADER, ...EN_CELLS]);
+    expect(await xlsxRows((await exportFile(exportRoute, 'xlsx', { acceptLanguage: 'zh-CN' })).buffer()))
+      .toEqual([ZH_HEADER, ...ZH_CELLS]);
+  });
+
+  it('json writes the same words as csv, per caller', async () => {
+    const { exportRoute } = await boot(i18nService('en'));
+    const en = JSON.parse((await exportFile(exportRoute, 'json', { acceptLanguage: 'en-US' })).text());
+    expect(en.map((r: any) => [r.is_converted, r.do_not_call])).toEqual([['yes', 'no'], ['no', 'yes']]);
+    const zh = JSON.parse((await exportFile(exportRoute, 'json', { acceptLanguage: 'zh-CN' })).text());
+    expect(zh.map((r: any) => [r.is_converted, r.do_not_call])).toEqual([['是', '否'], ['否', '是']]);
+  });
+
+  it('`?locale=` picks the language of the header and the cells alike', async () => {
+    const { exportRoute } = await boot(i18nService('en'));
+    const rows = csvRows((await exportFile(exportRoute, 'csv', { locale: 'zh-CN' })).text());
+    expect(rows).toEqual([ZH_HEADER, ...ZH_CELLS]);
+  });
+
+  it('a caller naming no locale gets the deployment default locale in the header and the cells alike', async () => {
+    // The default locale is read off the i18n service. Both halves of the
+    // file must read it from the SAME service, or a zh-CN deployment would
+    // write a Chinese header over English cells to every header-less caller.
+    const zh = await boot(i18nService('zh-CN'));
+    expect(csvRows((await exportFile(zh.exportRoute, 'csv')).text())).toEqual([ZH_HEADER, ...ZH_CELLS]);
+    const en = await boot(i18nService('en'));
+    expect(csvRows((await exportFile(en.exportRoute, 'csv')).text())).toEqual([EN_HEADER, ...EN_CELLS]);
+  });
+
+  it('no locale at all and no i18n service: the authored header and templateText(undefined) words', async () => {
+    const { exportRoute } = await boot(null);
+    const [yes, no] = templateText(undefined).booleanWords;
+    const rows = csvRows((await exportFile(exportRoute, 'csv')).text());
+    expect(rows).toEqual([EN_HEADER, ['1', 'Wren Halvorsen', yes, no], ['2', 'Tomas Okafor', no, yes]]);
+  });
+});
+
+describe('export → import: each language re-imports its boolean column', () => {
+  const MAPPINGS: Record<'en' | 'zh', Record<string, string>> = {
+    en: { 'ID': 'id', 'Full Name': 'full_name', 'Converted': 'is_converted', 'Do Not Call': 'do_not_call' },
+    zh: { '编号': 'id', '姓名': 'full_name', '已转化': 'is_converted', '请勿致电': 'do_not_call' },
+  };
+
+  for (const [lang, acceptLanguage] of [['en', 'en-US'], ['zh', 'zh-CN']] as const) {
+    it(`${lang}: csv`, async () => {
+      const source = await boot(i18nService('en'));
+      const csv = (await exportFile(source.exportRoute, 'csv', { acceptLanguage })).text();
+
+      const target = await boot(i18nService('en'), []);
+      const { res } = makeRes();
+      await target.importRoute.handler({
+        params: { object: 'lead' },
+        headers: { 'accept-language': acceptLanguage },
+        body: { format: 'csv', csv, mapping: MAPPINGS[lang] },
+      } as any, res);
+      expect(res._json).toMatchObject({ total: 2, ok: 2, errors: 0, created: 2 });
+      const stored = await target.engine.find('lead', { orderBy: [{ field: 'id', order: 'asc' }] });
+      expect(stored.map((r: any) => [r.id, r.is_converted, r.do_not_call]))
+        .toEqual([['1', true, false], ['2', false, true]]);
+    });
+
+    it(`${lang}: xlsx`, async () => {
+      const source = await boot(i18nService('en'));
+      const xlsxBase64 = (await exportFile(source.exportRoute, 'xlsx', { acceptLanguage })).buffer().toString('base64');
+
+      const target = await boot(i18nService('en'), []);
+      const { res } = makeRes();
+      await target.importRoute.handler({
+        params: { object: 'lead' },
+        headers: { 'accept-language': acceptLanguage },
+        body: { format: 'xlsx', xlsxBase64, mapping: MAPPINGS[lang] },
+      } as any, res);
+      expect(res._json).toMatchObject({ total: 2, ok: 2, errors: 0, created: 2 });
+      const stored = await target.engine.find('lead', { orderBy: [{ field: 'id', order: 'asc' }] });
+      expect(stored.map((r: any) => [r.id, r.is_converted, r.do_not_call]))
+        .toEqual([['1', true, false], ['2', false, true]]);
+    });
+  }
+});