feat(i18n): translate the four highest-traffic namespaces into the eight trailing locales (#2872 part a)

.changeset/high-frequency-locale-backfill.md

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+---
+"@object-ui/i18n": patch
+---
+
+feat(i18n): translate the four highest-traffic namespaces into the eight trailing locales (objectui#2872 part a)
+
+Backfills `console`, `home`, `topbar` and `layout` — 193 keys × 8 packs, 1,544
+strings — so a ja/ko/de/fr/es/pt/ru/ar admin sees the AI console, the home
+screen, the top bar and the system navigation in their own language instead of
+silently falling back to English.
+
+The gap in those eight packs drops from **469–471 keys to 277–279**. `en` and
+`zh` remain at exact parity (2499 : 2499, zero difference in both directions).
+
+This is the "high-frequency namespaces only" strategy from the objectui#2872
+discussion, not a full backfill: `grid` (101), `gantt` (58), `dashboard` (25)
+and the long tail stay on English fallback and remain tracked there.
+
+**Four keys are deliberately left untranslated**, and that is the load-bearing
+part of this change:
+
+```
+console.ai.planApproveMessage
+console.ai.planApproveDefaultsMessage
+console.ai.planAnswerMessage
+console.ai.changesConfirmMessage
+```
+
+These are not labels. They are the text a button *transmits to the agent*, and
+the cloud confirm gate (`service-ai-studio` `confirm-gate.ts` `APPROVAL_RE`)
+decides whether that text reads as approval. It recognises Chinese and English
+— nothing else. `AiChatPage` therefore selects them by the language of the
+CONVERSATION rather than of the UI, and the `t()` call is *expected* to miss in
+every non-Chinese pack and fall through to its English `defaultValue`.
+
+Translating them would be an outright regression: a German user's "Build it"
+would start sending German, the gate would stop matching, and the agent would
+re-propose instead of building — the button looks inert while nothing visibly
+errors.
+
+objectui#2900 shipped precisely that bug for `changesConfirmMessage`, which had
+been added to all ten packs. **This change removes it from the eight**,
+restoring the English fallback. A new guard,
+`packages/i18n/src/__tests__/outbound-agent-messages.test.ts`, pins the
+invariant in both directions: the four keys must be absent from the eight packs
+AND present in `en`/`zh`, while every *other* `console.ai` label must be
+translated — so the narrow fix can't be over-applied into an excuse for leaving
+surrounding labels in English.
+
+Translations are model-generated and would benefit from native review; the
+placeholder set of every string was verified programmatically against the
+English source.

packages/i18n/src/__tests__/outbound-agent-messages.test.ts

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+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Guard: the strings the console SENDS to the AI agent must not be translated
+ * into arbitrary locales.
+ *
+ * Most `console.ai.*` keys are labels and should be localized everywhere. Four
+ * are not labels — they are the message text a button transmits to the agent,
+ * and the cloud confirm gate (`service-ai-studio` `confirm-gate.ts`
+ * `APPROVAL_RE`) decides whether that text counts as approval. It recognises
+ * Chinese and English. Nothing else.
+ *
+ * So `AiChatPage` picks them by the language of the CONVERSATION, not the UI:
+ *
+ *     const planApproveMessage = convZh
+ *       ? '确认，开始搭建。'                                   // matches the gate
+ *       : t('console.ai.planApproveMessage', { defaultValue: … });
+ *
+ * That `t()` call is expected to MISS in every non-Chinese pack and fall
+ * through to its English `defaultValue`. Add a German translation and a German
+ * user's "Build it" click starts sending German, the gate stops matching, and
+ * the agent re-proposes instead of building — the button looks inert while
+ * nothing visibly errors. objectui#2900 shipped exactly that for
+ * `changesConfirmMessage`; this test is why it can't happen twice.
+ *
+ * If the gate ever learns more languages, delete the offending entry here in
+ * the same change that teaches it — not before.
+ */
+import { describe, it, expect } from 'vitest';
+import { en, zh, ja, ko, de, fr, es, pt, ru, ar } from '../locales';
+
+const OUTBOUND_KEYS = [
+  'console.ai.planApproveMessage',
+  'console.ai.planApproveDefaultsMessage',
+  'console.ai.planAnswerMessage',
+  'console.ai.changesConfirmMessage',
+] as const;
+
+const GATE_LOCALES: Record<string, unknown> = { en, zh };
+const NON_GATE_LOCALES: Record<string, unknown> = { ja, ko, de, fr, es, pt, ru, ar };
+
+function lookup(pack: unknown, dotted: string): unknown {
+  return dotted
+    .split('.')
+    .reduce<unknown>((node, part) => (node as Record<string, unknown>)?.[part], pack);
+}
+
+describe('outbound agent messages stay on gate-recognised languages', () => {
+  it.each(Object.keys(NON_GATE_LOCALES))(
+    'the %s pack defines none of them, so t() falls through to the English default',
+    (lang) => {
+      const offenders = OUTBOUND_KEYS.filter(
+        (k) => lookup(NON_GATE_LOCALES[lang], k) !== undefined,
+      );
+      expect(offenders).toEqual([]);
+    },
+  );
+
+  it.each(Object.keys(GATE_LOCALES))('the %s pack defines all of them', (lang) => {
+    for (const k of OUTBOUND_KEYS) {
+      expect(typeof lookup(GATE_LOCALES[lang], k)).toBe('string');
+    }
+  });
+
+  it('every OTHER console.ai key IS localized — this guard is narrow on purpose', () => {
+    // Guards against over-correcting: the fix for the outbound keys must not
+    // become a reason to leave the surrounding labels untranslated.
+    const aiLabels = Object.keys((en as any).console.ai).filter(
+      (k) => typeof (en as any).console.ai[k] === 'string',
+    );
+    const outboundLeaf = new Set(OUTBOUND_KEYS.map((k) => k.split('.').pop()));
+    const labels = aiLabels.filter((k) => !outboundLeaf.has(k));
+    expect(labels.length).toBeGreaterThan(20);
+    for (const k of labels) {
+      expect((de as any).console.ai[k], `de is missing console.ai.${k}`).toBeTypeOf('string');
+    }
+  });
+});