feat(client): typed locale standard seat in the slot framework

Registrations declare a dictionary namespace (locale: NS) and the renderer
synthesizes a typed t prop for the entry's component from the installed
LocaleFace; the seat binding is re-derived per locale revision, so a language
switch hands out fresh t references and memoized consumers re-render through
ordinary shallow comparison. LocaleNamespaceMap is the declare-merge table
(namespace -> dictionary key union); TranslateNS<'ns'> is the
namespace-addressed translate type (namespace keys plus the shared common
vocabulary), carried by the t seat and by the locale service's typed bind.

LocaleService implements the face (lookup ns -> common -> zh -> key,
revision-carrying snapshots with subscriber isolation) and installs it
through the boot-once slots.installLocale seam, mirroring the renderer
install. The typed register(ns, {zh, en}) overload checks each dictionary
against the namespace's key union and requires every shipped locale, so a
missing or extra key and an unbalanced translation are compile errors.
Dictionary registration bumps the face revision without emitting
locale/change — the event now means exactly 'the active locale switched',
so registration-heavy boot cannot storm event listeners.

packages/client/locale/README.i18n.yaml

@@ -1,6 +1,6 @@
 # Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
-#   pnpm run verify-translation-pairing --write
-README.md: 9015af2b44a33771b06863ace139fe97695df616
-README.zh.md: 6b129bcabbef5b5a00c5073ebc9142a0e406ddba
+#   pnpm run verify-translation-pairing --write packages/client/locale/README.md
+README.md: c2adbcabc77def740094288da4643032873aa5b8
+README.zh.md: 6232a98168a0a8fef3f8209ef6af8a3ce411f2be

packages/client/locale/README.md

@@ -2,7 +2,7 @@
 
 English | [中文](README.zh.md)
 
-Locale plugin: LocaleService — the browser locale preference (`zh`/`en`, persisted under `dsh.locale`, getter/setter with `locale/change` snapshots) plus the ns×locale dictionary registry (`bind(ns)`→t with a stable function identity; lookup chain active → zh → key).
+Locale plugin: LocaleService — the browser locale preference (`zh`/`en`, persisted under `dsh.locale`; `locale/change` fires on switches only) plus the ns×locale dictionary registry (typed `register(ns, {zh, en})` checked against `LocaleNamespaceMap`, `bind(ns)`→`TranslateNS<ns>`; lookup chain ns → common → zh → key). The service implements the slot system's `LocaleFace` and installs itself through `ctx.slots.installLocale`, backing the framework-injected `t` standard seat (`Translate`/`TranslateNS` are ui-slots types; import them from there — this package only re-exports for dictionary owners' convenience).
 
 ## Model Experience
 
@@ -14,5 +14,5 @@ None; this package neither assembles nor sends a provider request.
 
 ## Known Limitations and Deferred Work
 
-- **Only the Settings surface is translated** — other pages keep inline copy; repo-wide extraction into dictionaries is deferred.
-- **Locale switching re-renders subscribed consumers only** — sections not wired to `locale/change` keep their rendered text until remount.
+- **Most surfaces keep inline copy** — the standard seat is adopted by the Settings rows, sidebar, question composer, and model select; the remaining packages migrate in follow-up PRs.
+- **Registry-held text reads its translation once** — copy captured at registration time outside the slot render path (e.g. the `/model` command description in the command registry) keeps the language it was registered under until re-registration; slot-rendered copy follows switches live.

packages/client/locale/README.zh.md

@@ -2,7 +2,7 @@
 
 [English](README.md) | 中文
 
-locale 插件：LocaleService 包含浏览器 locale 偏好（`zh`／`en`，以 `dsh.locale` 为键持久化；提供 getter／setter，并生成 `locale/change` 快照），以及 ns×locale 字典注册表（`bind(ns)`→t 的函数标识稳定；查找链为 active → zh → key）。
+locale 插件：LocaleService——浏览器 locale 偏好（`zh`／`en`，以 `dsh.locale` 持久化；`locale/change` 仅在切换语言时触发），加上 ns×locale 字典注册表（类型化 `register(ns, {zh, en})` 按 `LocaleNamespaceMap` 校验，`bind(ns)`→`TranslateNS<ns>`；查找链 ns → common → zh → key）。该服务实现 slot 系统的 `LocaleFace` 并经 `ctx.slots.installLocale` 自行安装，支撑框架注入的 `t` 标准席位（`Translate`／`TranslateNS` 是 ui-slots 的类型；请从那里导入——本包的再导出仅为字典所有者提供便利）。
 
 ## 模型体验
 
@@ -14,5 +14,5 @@ locale 插件：LocaleService 包含浏览器 locale 偏好（`zh`／`en`，以
 
 ## 已知限制与暂缓事项
 
-- **只有设置界面完成翻译**：其他页面仍保留内联文案；将全仓文案提取到字典的工作暂缓。
-- **切换 locale 只重新渲染已订阅的消费方**：未接入 `locale/change` 的分区会保留已渲染文本，直到重新挂载。
+- **多数界面仍保留内联文案**——标准席位已由设置行、侧边栏、问题作答器和模型选择接入；其余包在后续 PR 中迁移。
+- **注册表持有的文本只读取一次翻译**——在 slot 渲染路径之外于注册时捕获的文案（例如 command 注册表中的 `/model` 命令描述）在重新注册前保持注册时的语言；slot 渲染的文案随切换实时更新。

packages/client/locale/src/client/LanguageRow.tsx

@@ -5,23 +5,22 @@
  * settings surface.
  */
 import { useState } from 'react'
-import type { PropsRuntime, PropsStore } from '@deepseek-ai/dsh-client-ui-slots'
+import type { PropsLocale, PropsRuntime, PropsStore } from '@deepseek-ai/dsh-client-ui-slots'
 import { IconChevronDownOutline14, Menu } from '@deepseek-ai/dsh-client-ui-primitives'
 import type {} from './settings-contract.ts'
 import type { createLanguageRowStore } from './settings-store.ts'
 import css from './LanguageRow.module.css'
 
-/** Injected business face: namespace-bound translate + the preference write. */
+/** Injected business face: the preference write (t rides the standard locale seat). */
 export interface LanguageRowInjected {
-  /** Translate a `settings.locale` dictionary key to the active-locale text. */
-  t: (key: string) => string
   /** Switch the active locale (a registered locale id). */
   setLocale: (id: string) => void
 }
 
-/** Full component props: runtime share + store share + injected face. */
+/** Full component props: runtime share + store share + locale seat + injected face. */
 export type LanguageRowComponentProps =
-  PropsRuntime<'settings.general.item'> & PropsStore<ReturnType<typeof createLanguageRowStore>> & LanguageRowInjected
+  PropsRuntime<'settings.general.item'> & PropsStore<ReturnType<typeof createLanguageRowStore>>
+  & PropsLocale<'settings.locale'> & LanguageRowInjected
 
 /**
  * Render the Language row.

packages/client/locale/src/client/index.ts

@@ -4,11 +4,21 @@
  * preference row into the settings General section — the locale feature owns
  * its own settings surface.
  */
+/* eslint-disable @typescript-eslint/no-redundant-type-constituents --
+ * `keyof LocaleNamespaceMap & string` is the declare-merge key pattern (see
+ * ui-slots): in THIS unit the map holds only this package's own merges, but
+ * consumers merge more namespaces in and the intersection keeps them
+ * string-typed. The rule fires on the narrow-map view, not real redundancy. */
 import type { Context } from 'cordis'
-import { deferRegistration, type BoundActions } from '@deepseek-ai/dsh-client-ui-slots'
+import {
+  deferRegistration,
+  type BoundActions, type LocaleDictOf, type LocaleNamespaceMap, type Translate, type TranslateNS,
+} from '@deepseek-ai/dsh-client-ui-slots'
 import type { ClientContext } from '@deepseek-ai/dsh-client-runtime/client'
-import { en } from '../locales/en.ts'
-import { zh } from '../locales/zh.ts'
+import { en, zh, type CommonKey } from '../locales/index.ts'
+import {
+  en as settingsEn, zh as settingsZh, type SettingsLocaleKey,
+} from '../locales/settings.ts'
 import type { LanguageRowInjected } from './LanguageRow.tsx'
 import { LanguageRow } from './LanguageRow.tsx'
 import { createLanguageRowStore } from './settings-store.ts'
@@ -16,9 +26,21 @@ import { createLanguageRowStore } from './settings-store.ts'
 export type { LanguageRowComponentProps, LanguageRowInjected } from './LanguageRow.tsx'
 export type { LanguageOptionRow, LanguageRowState } from './settings-store.ts'
 export type { SettingsGeneralItemOwnerProps } from './settings-contract.ts'
+export type { CommonKey } from '../locales/index.ts'
 
-/** Translate a key with optional params. */
-export type Translate = (key: string, params?: Record<string, unknown>) => string
+// The translate currency lives in ui-slots (the render machinery synthesizes
+// the seat); re-exported here so dictionary owners import one package.
+// TranslateNS<'model'> is the namespace-addressed developer-facing form.
+export type { Translate, TranslateNS } from '@deepseek-ai/dsh-client-ui-slots'
+
+declare module '@deepseek-ai/dsh-client-ui-slots' {
+  interface LocaleNamespaceMap {
+    /** Shared cross-feature vocabulary, consulted by the lookup chain after the entry's own namespace misses. */
+    common: CommonKey
+    /** This feature's own settings-row copy (the Language row). */
+    'settings.locale': SettingsLocaleKey
+  }
+}
 
 /** Locale dictionary: flat key to template string ({name} placeholders). */
 export type LocaleDict = Record<string, string>
@@ -50,7 +72,10 @@ declare module 'cordis' {
   }
   interface Events {
     /**
-     * Locale state changed (active locale switched or registry updated).
+     * The active locale switched. Dictionary registrations do NOT emit this
+     * event (listeners may re-register slots in response, and boot registers
+     * one namespace per package); continuous render refresh rides the
+     * LocaleFace revision instead.
      * @param snapshot - Current immutable locale snapshot.
      * @mode emit
      */
@@ -77,16 +102,20 @@ const LOCALES: readonly LocaleDefinition[] = Object.freeze([
 ])
 
 /**
- * Dictionary registry plus locale preference. Lookup chain per key: active
- * locale -> zh fallback -> the key itself (missing text stays visible, fail
- * loud in the UI rather than blank). Reads go through {@link getLocale};
- * writes only through {@link setLocale}; continuous sync only through the
- * `locale/change` event.
+ * Dictionary registry plus locale preference. Lookup chain per key: the
+ * entry's namespace in the active locale -> that namespace's zh fallback ->
+ * the shared common namespace (active, then zh) -> the key itself (missing
+ * text stays visible, fail loud in the UI rather than blank). Reads go
+ * through {@link getLocale}; writes only through {@link setLocale};
+ * continuous sync through the `locale/change` event, or through the
+ * LocaleFace getSnapshot/subscribe pair the render machinery consumes
+ * (installed via `ctx.slots.installLocale`).
  */
 export class LocaleService {
   private dicts = new Map<string, Map<string, LocaleDict>>()
   private bound = new Map<string, Translate>()
   private snapshot: LocaleSnapshot
+  private listeners = new Set<() => void>()
   private readonly ctx: Context
 
   /**
@@ -105,6 +134,27 @@ export class LocaleService {
     return this.snapshot
   }
 
+  /**
+   * LocaleFace getSnapshot: the current snapshot (carries `revision`; stable
+   * reference between changes, uSES-safe).
+   * @returns the current snapshot.
+   */
+  getSnapshot(): LocaleSnapshot {
+    return this.snapshot
+  }
+
+  /**
+   * LocaleFace subscribe: notified on every snapshot change (locale switch
+   * or dictionary registration — registrations bump the revision so already
+   * rendered outlets pick up late-arriving dictionaries).
+   * @param fn - change callback.
+   * @returns unsubscribe.
+   */
+  subscribe(fn: () => void): () => void {
+    this.listeners.add(fn)
+    return () => { this.listeners.delete(fn) }
+  }
+
   /**
    * Switch the active locale — the only preference write entry. Persists the
    * id and emits `locale/change`.
@@ -114,44 +164,80 @@ export class LocaleService {
     const match = this.snapshot.locales.find(l => l.id === id)
     if (match === undefined) throw new Error(`locale "${id}" is not registered`)
     if (this.snapshot.active === match.id) return
-    this.snapshot = Object.freeze({
-      active: match.id,
-      locales: this.snapshot.locales,
-      revision: this.snapshot.revision + 1,
-    })
     persistPreference(match.id)
-    this.ctx.emit('locale/change', this.snapshot)
+    this.publish(match.id, true)
   }
 
   /**
-   * Register a dictionary for a namespace and locale. Duplicate (ns, locale)
-   * throws (single occupant; a namespace's texts have one owner).
+   * Register a declared namespace's dictionaries, all locales in one call —
+   * the typed form: each dictionary is checked against the namespace's
+   * {@link LocaleNamespaceMap} key union (a missing or extra key is a
+   * compile error), and every shipped locale is required (bilingual balance
+   * enforced at the seam). Duplicate (ns, locale) throws (single occupant; a
+   * namespace's texts have one owner). Registration bumps the revision so
+   * mounted outlets pick up late-arriving dictionaries.
+   * @param ns - a namespace merged into LocaleNamespaceMap.
+   * @param dicts - complete dictionaries keyed by locale id.
+   * @returns disposer removing every locale registered by this call (idempotent).
+   */
+  register<N extends keyof LocaleNamespaceMap & string>(ns: N, dicts: Record<LocaleId, LocaleDictOf<N>>): () => void
+  /**
+   * Single-locale untyped form for namespaces outside the merge table
+   * (dynamic composition, tests).
    * @param ns - namespace.
-   * @param locale - locale tag (zh/en to start).
+   * @param locale - locale tag.
    * @param dict - dictionary.
    * @returns disposer (idempotent).
    */
-  register(ns: string, locale: string, dict: LocaleDict): () => void {
+  register(ns: string, locale: string, dict: LocaleDict): () => void
+  register(ns: string, localeOrDicts: string | Record<string, LocaleDict>, dict?: LocaleDict): () => void {
+    const pairs: [string, LocaleDict][] = typeof localeOrDicts === 'string'
+      // Overload guarantees dict on the single-locale arm.
+      ? [[localeOrDicts, dict as LocaleDict]]
+      : Object.entries(localeOrDicts)
     let locales = this.dicts.get(ns)
     if (!locales) {
       locales = new Map()
       this.dicts.set(ns, locales)
     }
-    if (locales.has(locale)) throw new Error(`locale namespace "${ns}" already has locale "${locale}"`)
-    locales.set(locale, dict)
+    for (const [locale] of pairs) {
+      if (locales.has(locale)) throw new Error(`locale namespace "${ns}" already has locale "${locale}"`)
+    }
+    for (const [locale, entries] of pairs) locales.set(locale, entries)
+    this.publish(this.snapshot.active, false)
     return () => {
       const owner = this.dicts.get(ns)
-      if (owner?.get(locale) === dict) owner.delete(locale)
+      /* v8 ignore next -- defensive: a namespace's locales map is created on
+       * first register and never removed, so the disposer always finds it. */
+      if (!owner) return
+      let removed = false
+      for (const [locale, entries] of pairs) {
+        if (owner.get(locale) === entries) {
+          owner.delete(locale)
+          removed = true
+        }
+      }
+      if (removed) this.publish(this.snapshot.active, false)
     }
   }
 
   /**
-   * Bind a namespace to a translate function. The returned reference is
-   * stable per namespace (repeat binds return the same function), so it can
-   * ride inject surfaces without breaking memoization.
-   * @param ns - namespace.
-   * @returns the translate function (reads the active locale at call time).
+   * Bind a declared namespace to a translate function typed to its
+   * dictionary key union (plus the shared common vocabulary) — the same key
+   * domain the framework-injected `t` seat carries. The returned reference
+   * is stable per namespace (repeat binds return the same function), so it
+   * can ride inject surfaces without breaking memoization.
+   * @param ns - a namespace merged into LocaleNamespaceMap.
+   * @returns the typed translate function (reads the active locale at call time).
    */
+  bind<N extends keyof LocaleNamespaceMap & string>(ns: N): TranslateNS<N>
+  /**
+   * Untyped form for namespaces outside the merge table (dynamic
+   * composition, tests).
+   * @param ns - namespace.
+   * @returns the translate function.
+   */
+  bind(ns: string): Translate
   bind(ns: string): Translate {
     let t = this.bound.get(ns)
     if (!t) {
@@ -163,14 +249,43 @@ export class LocaleService {
   }
 
   private translate(ns: string, key: string, params?: Record<string, unknown>): string {
-    const locales = this.dicts.get(ns)
-    const template = locales?.get(this.snapshot.active)?.[key]
-      ?? locales?.get(FALLBACK_LOCALE)?.[key]
+    const template = this.lookup(ns, key)
+      ?? (ns !== COMMON_NS ? this.lookup(COMMON_NS, key) : undefined)
       ?? key
     if (!params) return template
     return template.replace(/\{(\w+)\}/g, (match, name: string) =>
       name in params ? String(params[name]) : match)
   }
+
+  private lookup(ns: string, key: string): string | undefined {
+    const locales = this.dicts.get(ns)
+    return locales?.get(this.snapshot.active)?.[key] ?? locales?.get(FALLBACK_LOCALE)?.[key]
+  }
+
+  /**
+   * Advance the snapshot revision and notify LocaleFace subscribers (render
+   * refresh). Only an active-locale switch additionally emits
+   * `locale/change` — dictionary registrations stay off the event so
+   * registration-heavy boot cannot storm event listeners (which may
+   * re-register slots in response).
+   */
+  private publish(active: LocaleId, localeChanged: boolean): void {
+    this.snapshot = Object.freeze({
+      active,
+      locales: this.snapshot.locales,
+      revision: this.snapshot.revision + 1,
+    })
+    if (localeChanged) this.ctx.emit('locale/change', this.snapshot)
+    for (const fn of [...this.listeners]) {
+      try {
+        fn()
+      } catch (error) {
+        // One throwing subscriber must not strand the rest on a stale
+        // revision (outlets would keep the previous language).
+        console.error('locale subscriber crashed:', error)
+      }
+    }
+  }
 }
 
 /** Read the persisted locale id; unknown or unreadable values fall back to zh. */
@@ -208,11 +323,12 @@ export const inject = ['slots']
  */
 export function apply(ctx: ClientContext): void {
   const locale = new LocaleService(ctx)
-  locale.register(COMMON_NS, 'zh', zh)
-  locale.register(COMMON_NS, 'en', en)
-  locale.register(SETTINGS_NS, 'zh', { 'language.title': '语言' })
-  locale.register(SETTINGS_NS, 'en', { 'language.title': 'Language' })
+  locale.register(COMMON_NS, { zh, en })
+  locale.register(SETTINGS_NS, { zh: settingsZh, en: settingsEn })
   ctx.provide('locale', locale)
+  // The service IS the LocaleFace (bind + getSnapshot/subscribe): install it
+  // so the render machinery can synthesize the `t` standard seat.
+  ctx.slots.installLocale(locale)
 
   const store = createLanguageRowStore()
   let bound: BoundActions<typeof store> | undefined
@@ -230,7 +346,6 @@ export function apply(ctx: ClientContext): void {
     // first render (the store's revision guard drops stale duplicates).
     sync(locale.getLocale())
     return {
-      t: locale.bind(SETTINGS_NS),
       setLocale: (id) => { locale.setLocale(id) },
     }
   }
@@ -241,6 +356,7 @@ export function apply(ctx: ClientContext): void {
         id: 'language',
         order: 0,
         store,
+        locale: SETTINGS_NS,
         inject: injected,
       }, LanguageRow))
     return () => { deferred.dispose() }

packages/client/locale/src/locales/en.ts

@@ -1,2 +1,29 @@
-/** en base dictionary for the common namespace (starter skeleton; texts land with their features). */
-export const en: Record<string, string> = {}
+import type { CommonKey } from './zh.ts'
+
+/** en base dictionary for the common namespace, checked complete against the zh key set. */
+export const en = {
+  'ok': 'OK',
+  'cancel': 'Cancel',
+  'close': 'Close',
+  'copy': 'Copy',
+  'copied': 'Copied',
+  'retry': 'Retry',
+  'loading': 'Loading…',
+  'load.failed': 'Failed to load',
+  'submit': 'Submit',
+  'submitting': 'Submitting…',
+  'next': 'Next',
+  'previous': 'Previous',
+  'skip': 'Skip',
+  'delete': 'Delete',
+  'edit': 'Edit',
+  'save': 'Save',
+  'search': 'Search',
+  'more': 'More',
+  'collapse': 'Collapse',
+  'expand': 'Expand',
+  'back': 'Back',
+  'unknown': 'Unknown',
+  'none': 'None',
+  'truncated': 'Truncated',
+} satisfies Record<CommonKey, string>

packages/client/locale/src/locales/index.ts

@@ -0,0 +1,8 @@
+/**
+ * The common-namespace dictionary pair. zh is the source of truth for the
+ * key set (Chinese-first repo convention); en is checked complete against it
+ * — a missing or extra en key is a compile error.
+ */
+export { zh } from './zh.ts'
+export { en } from './en.ts'
+export type { CommonKey } from './zh.ts'

packages/client/locale/src/locales/settings.ts

@@ -0,0 +1,14 @@
+/** `settings.locale` namespace dictionaries (the Language row's copy). */
+
+/** Simplified Chinese dictionary (the key-set source of truth). */
+export const zh = {
+  'language.title': '语言',
+} satisfies Record<string, string>
+
+/** The settings.locale namespace key union. */
+export type SettingsLocaleKey = keyof typeof zh
+
+/** English dictionary, checked complete against the zh key set. */
+export const en = {
+  'language.title': 'Language',
+} satisfies Record<SettingsLocaleKey, string>

packages/client/locale/src/locales/zh.ts

@@ -1,2 +1,30 @@
-/** zh base dictionary for the common namespace (starter skeleton; texts land with their features). */
-export const zh: Record<string, string> = {}
+/** zh base dictionary for the common namespace: cross-feature standard words. */
+export const zh = {
+  'ok': '确定',
+  'cancel': '取消',
+  'close': '关闭',
+  'copy': '复制',
+  'copied': '复制成功',
+  'retry': '重试',
+  'loading': '加载中…',
+  'load.failed': '加载失败',
+  'submit': '提交',
+  'submitting': '正在提交…',
+  'next': '下一步',
+  'previous': '上一步',
+  'skip': '跳过',
+  'delete': '删除',
+  'edit': '编辑',
+  'save': '保存',
+  'search': '搜索',
+  'more': '更多',
+  'collapse': '收起',
+  'expand': '展开',
+  'back': '返回',
+  'unknown': '未知',
+  'none': '无',
+  'truncated': '已截断',
+} satisfies Record<string, string>
+
+/** The common vocabulary key union (zh is the key-set source of truth). */
+export type CommonKey = keyof typeof zh

packages/client/locale/tests/apply.spec.ts

@@ -69,16 +69,18 @@ describe('locale apply', () => {
     // An event ahead of any inject hits the unbound-actions arm.
     locale.setLocale('en')
 
-    const { instance, face } = faceOf(b.slots)
+    const { entry, instance, face } = faceOf(b.slots)
     // The inject-time re-sync sealed the init window: the mirror is current.
     expect(instance.getSnapshot().active).toBe('en')
     expect(instance.getSnapshot().options.map(o => o.id)).toEqual(['zh', 'en'])
-    expect(face.t('language.title')).toBe('Language')
+    // Copy rides the standard locale seat: the entry declares the namespace.
+    expect(entry.locale).toBe(SETTINGS_NS)
+    expect(locale.bind(SETTINGS_NS)('language.title')).toBe('Language')
 
     face.setLocale('zh')
     expect(locale.getLocale().active).toBe('zh')
     expect(instance.getSnapshot().active).toBe('zh')
-    expect(face.t('language.title')).toBe('语言')
+    expect(locale.bind(SETTINGS_NS)('language.title')).toBe('语言')
   })
 
   it('recovers after an HMR collapse of the declaring entry (stale disposer must not block)', async () => {

packages/client/locale/tests/locale.spec.ts

@@ -29,6 +29,24 @@ describe('LocaleService', () => {
     expect(t('missing.key')).toBe('missing.key')
   })
 
+  it('falls through to the common vocabulary after the namespace misses (production keys)', () => {
+    const { svc } = make()
+    // The shipped common pair is registered by apply; the bench registers it
+    // directly to pin the production chain: ns -> common -> zh -> key.
+    svc.register('common', 'zh', { retry: '重试' })
+    svc.register('common', 'en', { retry: 'Retry' })
+    svc.register('ns', 'zh', { own: '自有' })
+    const t = svc.bind('ns')
+    expect(t('retry')).toBe('重试')
+    svc.setLocale('en')
+    expect(t('retry')).toBe('Retry')
+    expect(t('own')).toBe('自有')
+    // common itself must not recurse: a miss inside common echoes the key.
+    // (Wide-string ns hits the untyped bind overload — the typed one rejects
+    // unknown keys at compile time, which is the point of the seam.)
+    expect(svc.bind('common' as string)('nope')).toBe('nope')
+  })
+
   it('interpolates {name} params and leaves unknown placeholders intact', () => {
     const { svc } = make()
     svc.register('ns', 'zh', { greet: '你好，{name}！第 {n} 次', partial: '{known} 与 {unknown}' })
@@ -56,6 +74,47 @@ describe('LocaleService', () => {
     expect(t('k')).toBe('v2')
   })
 
+  it('serves the LocaleFace: snapshot revision moves on switch and registration, subscribers fire, unsubscribe stops them', () => {
+    const { svc } = make()
+    const seen: number[] = []
+    const off = svc.subscribe(() => { seen.push(svc.getSnapshot().revision) })
+    expect(svc.getSnapshot()).toBe(svc.getLocale())
+    const r0 = svc.getSnapshot().revision
+    svc.register('ns', 'zh', { k: 'v' })
+    expect(svc.getSnapshot().revision).toBe(r0 + 1)
+    svc.setLocale('en')
+    expect(seen).toEqual([r0 + 1, r0 + 2])
+    off()
+    svc.setLocale('zh')
+    expect(seen).toHaveLength(2)
+  })
+
+  it('isolates a throwing subscriber: the rest still see the new revision', () => {
+    const { svc } = make()
+    const spy = vi.spyOn(console, 'error').mockImplementation(() => {})
+    try {
+      const seen: number[] = []
+      svc.subscribe(() => { throw new Error('boom') })
+      svc.subscribe(() => { seen.push(svc.getSnapshot().revision) })
+      svc.setLocale('en')
+      expect(seen).toEqual([1])
+      expect(spy).toHaveBeenCalledOnce()
+    } finally {
+      spy.mockRestore()
+    }
+  })
+
+  it('register disposer republishes (mounted outlets drop the dead dictionary)', () => {
+    const { svc } = make()
+    const dispose = svc.register('ns', 'zh', { k: 'v' })
+    const before = svc.getSnapshot().revision
+    dispose()
+    expect(svc.getSnapshot().revision).toBe(before + 1)
+    // Second run hits the idempotent arm: nothing removed, no republish.
+    dispose()
+    expect(svc.getSnapshot().revision).toBe(before + 1)
+  })
+
   it('setLocale persists, republishes an immutable snapshot, and no-ops on same value', () => {
     const { svc, events } = make()
     svc.setLocale('en')