feat(app-shell): build the language menu from the app's locale list

[yinlianghui]

Fixes#4039

Implements the binding INTERSECTION ruling on the card: the switcher offers (the app's GET /api/v1/i18n/locales response) ∩ (what the renderer can resolve). The hardcoded ten survive only as the offline/no-backend fallback, and PR #3376's restore validation widens in this same PR, as the card's own warning required.

Premise check (verified on tip, before implementing)

All three parts of the premise held:

• LocaleSwitcher.tsx did build its menu from a module-level LANGUAGES constant — the ten built-in codes, never consulting the app.
• The restore validation's bound was what fix(i18n): 语言选择写入 localStorage 并在启动时恢复,刷新不再退回 en #3376 landed: isKnownLanguage = built-in packs ∪ config.resources.
• No client accessor existed for /api/v1/i18n/locales (only /i18n/translations/:locale, via apps/console/src/loadLanguage.ts), so adding a minimal one was in scope per the dispatch. It mirrors that sibling exactly.

The two sides of the intersection, as implemented

App side — a new loadLocales prop on I18nProvider, wired the same way as the existing loadLanguage: the app owns the transport, the provider owns what is done with the answer. apps/console/src/loadLocales.ts reads the real producer contract — GetLocalesResponseSchema declares { data: { locales: [{ code, label, isDefault }] } }, emitted through the shared toLocaleDescriptors by both serving surfaces.

Renderer side — built-in packs, config.resources, and the locales a wired dynamic loader can fetch. That last clause is load-bearing rather than generous: the console wires loadLanguage and no config.resources at all, so its app packs live behind GET /api/v1/i18n/translations/:locale. Without it the intersection in the real product would collapse to appLocales ∩ the built-in ten, and the card's first failure direction (an app shipping th) could never close.

One predicate serves both sides.canResolveLanguage is simultaneously the menu's right-hand side and the restore bound, so the two cannot drift apart — the lockstep is structural, not a convention someone has to remember. Reverse verification 2 below demonstrates this by construction.

Lockstep: the restore validation

A locale the user can now pick was a locale the old bound rejected, so the preference would have been purged on the next reload — the exact next bug objectstack#5418 predicted this fix would mint. The bound is widened, not removed:

• only well-formed BCP-47 tags qualify (Intl.getCanonicalLocales rejects constructor, __proto__, en_US) — the prototype-pollution guard fix(i18n): 语言选择写入 localStorage 并在启动时恢复,刷新不再退回 en #3376 wrote still holds;
• only for apps that wired a loader — an app without one keeps fix(i18n): 语言选择写入 localStorage 并在启动时恢复,刷新不再退回 en #3376's behaviour exactly;
• the app's own list adjudicates the choice once it arrives: a locale the app has since dropped is reverted and purged, so the "one stale entry can never lock the UI to a locale with no translations" invariant survives the widening. The purge happens after the revert, because every language change persists itself — clearing first would just be overwritten, recording an en preference the user never expressed and suppressing browser detection from then on.

Labels, loading, fallback

Built-in native names are kept where they exist (中文, 日本語, … unchanged); everything else is named by Intl.DisplayNames in its own locale. The endpoint's own label is deliberately not used for display — toLocaleDescriptors sets label: code, so a server label would put th in the menu where ไทย belongs. No new i18n keys are added: check:i18n-drift reports 0 en values changed, 0 keys added.

While the list is in flight the switcher renders nothing, following the closest existing idiom in the same folder (AppSwitcher, WorkspaceSwitcher both return null for data they do not have yet) — so the ten never flash past on an app that ships two. No backend, a failed endpoint, or an answer with nothing this renderer can produce all fall back to the built-in ten: the menu is never empty.

Reverse verification

1 — revert the switcher alone (git checkout origin/main -- LocaleSwitcher.tsx): predicted RED on the intersection and loading pins. Confirmed, 4 failed / 5 passed:

× offers an app-shipped locale outside the built-in ten, named by Intl.DisplayNames
× offers an app-shipped locale supplied through config.resources
× shows ONLY what the app ships — the phantom eight are gone
× renders nothing until the app has answered — no flash of the fallback ten

The 5 that stayed green are expected to stay green and were predicted to: the two fallback pins and the built-in-native-name control cannot go red by reverting the switcher, because the offline fallback is the old behaviour. Reported rather than manufactured into a red.

2 — revert the validation widening alone (canResolveLanguage's loader clause only, switcher intact): predicted RED on the restore pins. Confirmed, 4 failed / 8 passed:

× restores an app-shipped locale that has no built-in pack
× restores it in the BOOTSTRAP language, not as a late correction
× leaves the stored locale alone when the app answers with nothing
× is the app list ∩ what this renderer can resolve

I predicted three; the fourth is the informative one. offerableLanguages went red too because the same predicate feeds the menu — which is the lockstep proven by construction: you cannot revert the restore half without also shrinking the menu half.

One honest non-red: still drops a stale app locale when the app no longer ships it stays green under the narrow bound, because it reaches the same end state through the bootstrap purge instead of the self-heal.

Tests

New: LocaleSwitcher.appLocales.test.tsx (9), provider-app-locale-restore.test.tsx (12, incl. a StrictMode single-request pin — main.tsx mounts under React.StrictMode and an inline prop identity changes every render), loadLocales.test.ts (7).

packages/i18n/ Test Files 38 passed Tests 661 passed
packages/app-shell/ Test Files 342 passed Tests 3250 passed | 1 skipped
type-check (i18n + app-shell + console, turbo) 37 successful, 37 total
lint (same three) 3 successful, 0 errors
check:control-bytes OK (3965 tracked text files) + control-byte self-scan on every touched file: clean
check:i18n-keys OK check:i18n-drift 0 en values changed, 0 keys added
changeset:check OK

Changeset: .changeset/locale-menu-from-app-4039.md (@object-ui/i18n minor, @object-ui/app-shell + @object-ui/console patch). No skip-changeset.

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✅ Console Performance Budget

Metric	Value	Budget
Main entry (gzip)	28.5 KB	350 KB
Entry file	index-Dw6XJf9k.js	—
Status	PASS	—

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📦 Bundle Size Report

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app-shell (runtime-config.js)	7.42KB	2.32KB
app-shell (types.js)	0.01KB	0.04KB
app-shell (urlParams.js)	7.57KB	2.97KB
auth (AuthContext.js)	0.31KB	0.24KB
auth (AuthGuard.js)	1.17KB	0.53KB
auth (AuthProvider.js)	22.10KB	4.37KB
auth (AuthShell.js)	3.49KB	1.40KB
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auth (phone-identifier.js)	1.11KB	0.66KB
auth (types.js)	0.59KB	0.35KB
auth (useAuth.js)	4.91KB	0.87KB
auth (useIsWorkspaceAdmin.js)	1.61KB	0.85KB
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i18n (i18n.js)	4.32KB	1.77KB
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i18n (pickLocalized.js)	1.70KB	0.83KB
i18n (provider.js)	16.38KB	5.47KB
i18n (useObjectLabel.js)	27.59KB	6.63KB
i18n (useSafeTranslation.js)	4.52KB	1.96KB
layout (index.js)	38.98KB	10.85KB
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mobile (usePullToRefresh.js)	2.53KB	0.85KB
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plugin-grid (index.js)	187.97KB	49.90KB
plugin-kanban (index.js)	48.60KB	13.41KB
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types (http-retry.js)	4.32KB	2.02KB
types (index.js)	3.05KB	1.52KB
types (layout.js)	0.20KB	0.18KB
types (managed-by.js)	0.19KB	0.18KB
types (mobile.js)	2.59KB	1.31KB
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types (objectql.js)	0.20KB	0.18KB
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types (permissions.js)	0.20KB	0.18KB
types (plugin-scope.js)	0.20KB	0.18KB
types (record-components.js)	0.20KB	0.19KB
types (record-semantics.js)	1.28KB	0.67KB
types (registry.js)	0.20KB	0.18KB
types (reports.js)	0.20KB	0.18KB
types (spec-report.js)	5.05KB	1.93KB
types (system-fields.js)	3.33KB	1.54KB
types (theme.js)	0.20KB	0.18KB
types (ui-action.js)	3.40KB	1.71KB
types (views.js)	0.20KB	0.18KB
types (widget.js)	0.20KB	0.18KB

Size Limits

• ✅ Core packages should be < 50KB gzipped
• ✅ Component packages should be < 100KB gzipped
• ⚠️ Plugin packages should be < 150KB gzipped