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/ui-sidebar/src/client/SidebarRoot.tsx

@@ -32,6 +32,7 @@ export function SidebarRoot({
   width,
   startSession,
   toggleSidebar,
+  t,
   renderSlot,
 }: SidebarRootComponentProps) {
   // Wide content stays mounted while the collapse animates (fading via
@@ -67,7 +68,7 @@ export function SidebarRoot({
           <button
             type="button"
             className={clsx(css.brand, css.wide)}
-            aria-label="New session"
+            aria-label={t('session.new.label')}
             onClick={() => { startSession() }}
           >
             <BrandWordmark />
@@ -75,11 +76,11 @@ export function SidebarRoot({
         )}
         {/* Rail resting state is the whale mark; hovering swaps in the panel
             icon (the expand affordance, figma sidebar-hover flow). */}
-        <Tooltip label="Open sidebar" disabled={wide}>
+        <Tooltip label={t('toggle.open')} disabled={wide}>
           <button
             type="button"
             className={clsx(css.iconButton, css.toggle)}
-            aria-label={collapsed ? 'Open sidebar' : 'Collapse sidebar'}
+            aria-label={collapsed ? t('toggle.open') : t('toggle.collapse')}
             onClick={() => { toggleSidebar() }}
           >
             {!wide && <FishLogo className={css.railFish} size={24} />}
@@ -89,15 +90,15 @@ export function SidebarRoot({
         </Tooltip>
       </div>
 
-      <Tooltip label="New session" disabled={wide}>
+      <Tooltip label={t('session.new.label')} disabled={wide}>
         <button
           type="button"
           className={css.newSession}
-          aria-label="New session"
+          aria-label={t('session.new.label')}
           onClick={() => { startSession() }}
         >
           <IconNewChatOutline16 size={wide ? 14 : 18} />
-          {wide && <span className={clsx(css.newSessionLabel, css.wide)}>New Session</span>}
+          {wide && <span className={clsx(css.newSessionLabel, css.wide)}>{t('session.new')}</span>}
         </button>
       </Tooltip>
 

packages/client/ui-sidebar/src/client/contract/slots.ts

@@ -6,7 +6,7 @@
  * `sidebar.workspaces` registrant's (ui-workspace), and the foot is the
  * `sidebar.settings` registrant's (ui-settings).
  */
-import type { PropsRenderSlots, PropsRuntime } from '@deepseek-ai/dsh-client-ui-slots'
+import type { PropsLocale, PropsRenderSlots, PropsRuntime } from '@deepseek-ai/dsh-client-ui-slots'
 // Type-only: pulls ui-layout's SlotMap merge (the 'sidebar' entry) into every
 // program that sees this contract, so PropsRuntime<'sidebar'> resolves.
 import type {} from '@deepseek-ai/dsh-client-ui-layout/client'
@@ -68,7 +68,9 @@ export type SidebarRootInjected = {
 
 /**
  * Full component props: layout owner state/actions plus the declared holes'
- * render shares and this package's injected callbacks. No store is registered.
+ * render shares, this package's injected callbacks, and the standard locale
+ * seat. No store is registered.
  */
 export type SidebarRootComponentProps =
-  PropsRuntime<'sidebar'> & PropsRenderSlots<'sidebar.workspaces' | 'sidebar.settings'> & SidebarRootInjected
+  PropsRuntime<'sidebar'> & PropsRenderSlots<'sidebar.workspaces' | 'sidebar.settings'>
+  & SidebarRootInjected & PropsLocale<'sidebar'>

packages/client/ui-sidebar/src/client/index.ts

@@ -1,17 +1,33 @@
 /** Registers the sidebar shell into the layout-owned slot. */
 import type { ClientContext } from '@deepseek-ai/dsh-client-runtime/client'
+// Type-only: pulls the locale plugin's Context merge (ctx.locale).
+import type {} from '@deepseek-ai/dsh-client-locale/client'
 import type { SidebarRootInjected } from './contract/slots.ts'
 import { SidebarRoot } from './SidebarRoot.tsx'
+import { en, zh, type SidebarKey } from './locales.ts'
 
 export type { SidebarRootComponentProps, SidebarRootInjected, SidebarSectionOwnerProps, SidebarSettingsOwnerProps } from './contract/slots.ts'
+export type { SidebarKey } from './locales.ts'
+
+declare module '@deepseek-ai/dsh-client-ui-slots' {
+  interface LocaleNamespaceMap {
+    /** Sidebar shell controls copy. */
+    sidebar: SidebarKey
+  }
+}
+
+/** Dictionary namespace owned by this plugin (shell controls copy). */
+const NS = 'sidebar'
 
 /** Services required by the sidebar plugin. */
-export const inject = ['slots', 'layout', 'sessions', 'workspaces']
+export const inject = ['slots', 'layout', 'sessions', 'workspaces', 'locale']
 
 /** Registers the sidebar shell and its service callbacks.
  * @param ctx - Client root context.
  */
 export function apply(ctx: ClientContext): void {
+  ctx.effect(() => ctx.locale.register(NS, { zh, en }), 'ui-sidebar: dictionaries')
+
   const injectProps = (): SidebarRootInjected => ({
     // The shell's New Session button rides the runtime's shared action
     // (recent-Workspace targeting; explicit Workspace wins for scoped actions).
@@ -21,6 +37,7 @@ export function apply(ctx: ClientContext): void {
   ctx.effect(
     () => ctx.slots.register({
       name: 'sidebar',
+      locale: NS,
       // The shell owns geometry; ui-workspace registers the whole browsing
       // region (header, search, session list, workspace dialogs), ui-settings
       // registers the foot trigger + settings panel.

packages/client/ui-sidebar/src/client/locales.ts

@@ -0,0 +1,20 @@
+/** `sidebar` namespace dictionaries: shell controls (brand row, New Session, fold toggle). */
+
+/** Simplified Chinese dictionary (the key-set source of truth). */
+export const zh = {
+  'session.new': '新会话',
+  'session.new.label': '新建会话',
+  'toggle.open': '打开侧边栏',
+  'toggle.collapse': '收起侧边栏',
+} satisfies Record<string, string>
+
+/** The sidebar namespace key union. */
+export type SidebarKey = keyof typeof zh
+
+/** English dictionary, checked complete against the zh key set. */
+export const en: Record<SidebarKey, string> = {
+  'session.new': 'New Session',
+  'session.new.label': 'New session',
+  'toggle.open': 'Open sidebar',
+  'toggle.collapse': 'Collapse sidebar',
+}