feat(apes): revive the task/message tabs in the info layer

C6 removed apes:tasks as a duplicate of the host session panel; in practice the two answer different questions (host panel = switch workspaces, plugin tab = who is running right now), so the tab is restored and the info layer goes back to five types.

tasks: live session list (current / running / subagent markers) + showInactive toggle via pluginSettings['apes:tasks']; messages: placeholder that states the host has no message feed yet; both get badge counters, and the whole layer now honours the visible gate (auto-collapse) so hidden tabs stop waking on session events.

zh/en/ja dictionaries in sync (AGENTS 5); wiki 02/03/07 reverted from three to five tabs; decision record in docs/plans/2026-10-11-apes-tab-revival.md.

src/client/apes/icons.tsx

@@ -48,3 +48,23 @@ export function IconUserOutline16({ size = 16, className }: { size?: number; cla
     </svg>
   )
 }
+
+/** Tasks glyph: a rounded card carrying a check mark. */
+export function IconTasksOutline16({ size = 16, className }: { size?: number; className?: string }): ReactNode {
+  return (
+    <svg width={size} height={size} viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg" className={className}>
+      <rect x="1.5" y="1.5" width="13" height="13" rx="3.6" stroke="currentColor" strokeWidth="1.5" />
+      <path d="M4.7 8.2l2.2 2.2 4.4-4.8" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
+    </svg>
+  )
+}
+
+/** Messages glyph: a speech bubble with a lower-left tail. */
+export function IconMessagesOutline16({ size = 16, className }: { size?: number; className?: string }): ReactNode {
+  return (
+    <svg width={size} height={size} viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg" className={className}>
+      <path d="M1.5 5.1c0-2 1.6-3.6 3.6-3.6h5.8c2 0 3.6 1.6 3.6 3.6v3.1c0 2-1.6 3.6-3.6 3.6H6.6L2.9 14.5V11.5h-.2c-.7-.6-1.2-1.6-1.2-2.6z" stroke="currentColor" strokeWidth="1.5" strokeLinejoin="round" />
+      <path d="M5.4 7.4h5.2M5.4 4.9h3.1" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" />
+    </svg>
+  )
+}

src/client/apes/index.ts

@@ -1,9 +1,14 @@
 /**
  * apes:* information-layer tabs — the fork's own contribution on top of the
- * upstream dsh-better-sidebar. Three tabs ship (agents / apps / profile);
- * `apes:tasks` was removed (C6) because it overlaps the official DSH session
- * tree in the native sidebar, and `messages` is deferred (no DSH
- * message-stream API yet — tracked separately).
+ * upstream dsh-better-sidebar. Five tabs ship (tasks / agents / messages /
+ * apps / profile).
+ *
+ * History (C7): `apes:tasks` was removed under the old C6 decision (it looked
+ * redundant next to the official DSH session tree). The `v2-revive` line
+ * restores it — the native tree is a *navigator* (one focused lineage), this
+ * panel is a *list* (every session, with an idle filter and a running badge),
+ * so the two answer different questions. `messages` is still an honest
+ * placeholder: no DSH message-stream feed exists yet.
  *
  * Isolated under `src/client/apes/` so the upstream `builtins/` tree stays
  * untouched: cherry-picking upstream releases only has to keep the single
@@ -20,7 +25,7 @@ import { apesTabs } from './tabs.tsx'
 
 // Re-exported so index.tsx can register the apes dictionaries + attach the
 // locale service in one import (keeps the apes module self-contained).
-export { APES_LOCALE_NS, apesZh, apesEn, attachApesLocale } from './locales.ts'
+export { APES_LOCALE_NS, apesZh, apesEn, apesJa, attachApesLocale } from './locales.ts'
 
 /**
  * Register the apes:* tabs with the sidebar service. Returns a disposer that

src/client/apes/locales.ts

@@ -17,9 +17,19 @@ export const APES_LOCALE_NS = 'apes'
 /** The zh dictionary (source of truth). */
 export const apesZh = {
   // View titles
+  apesTasksTitle: '任务',
+  apesMessagesTitle: '消息',
   apesAgentsTitle: '智能体',
   apesAppsTitle: '应用',
   apesProfileTitle: '画像',
+  // Tasks view
+  apesTasksShowInactive: '显示空闲会话',
+  apesTasksEmpty: '当前没有会话',
+  apesTasksCurrent: '当前',
+  apesTasksRunning: '运行中',
+  apesTasksSubagent: '子智能体',
+  // Messages view
+  apesMessagesNoFeed: '当前 DSH 版本未提供消息流数据源',
   // Agents view
   apesAgentsEmpty: '当前会话没有子智能体',
   apesAgentsRoot: '主智能体',
@@ -40,9 +50,17 @@ export const apesZh = {
 
 /** The en dictionary (checked against zh — every zh key must appear here). */
 export const apesEn: Record<keyof typeof apesZh, string> = {
+  apesTasksTitle: 'Tasks',
+  apesMessagesTitle: 'Messages',
   apesAgentsTitle: 'Agents',
   apesAppsTitle: 'Apps',
   apesProfileTitle: 'Profile',
+  apesTasksShowInactive: 'Show idle sessions',
+  apesTasksEmpty: 'No sessions right now',
+  apesTasksCurrent: 'current',
+  apesTasksRunning: 'running',
+  apesTasksSubagent: 'subagent',
+  apesMessagesNoFeed: 'This DSH version exposes no message stream feed',
   apesAgentsEmpty: 'No subagents in this session',
   apesAgentsRoot: 'Main agent',
   apesAgentRunning: 'running',
@@ -60,7 +78,39 @@ export const apesEn: Record<keyof typeof apesZh, string> = {
 
 export type ApesCopyKey = keyof typeof apesZh
 
-/** Resolve the currently active DSH locale ('zh' | 'en' today). */
+/**
+ * The ja dictionary (AGENTS §5: a new zh key must land in ja in the same
+ * change, otherwise ja readers silently get the en text). Japanese is not a
+ * separate source of truth — it mirrors the en wording, never the zh one.
+ */
+export const apesJa: Record<keyof typeof apesZh, string> = {
+  apesTasksTitle: 'タスク',
+  apesMessagesTitle: 'メッセージ',
+  apesAgentsTitle: 'エージェント',
+  apesAppsTitle: 'アプリ',
+  apesProfileTitle: 'プロフィール',
+  apesTasksShowInactive: 'アイドル状態のセッションを表示',
+  apesTasksEmpty: 'セッションがありません',
+  apesTasksCurrent: '現在',
+  apesTasksRunning: '実行中',
+  apesTasksSubagent: 'サブエージェント',
+  apesMessagesNoFeed: 'この DSH バージョンはメッセージストリームの供給元を提供していません',
+  apesAgentsEmpty: 'このセッションにサブエージェントはいません',
+  apesAgentsRoot: 'メインエージェント',
+  apesAgentRunning: '実行中',
+  apesAgentInactive: 'アイドル',
+  apesAgentOneShot: '単発',
+  apesAgentContinuable: '継続可',
+  apesProfileCurrent: '現在のセッション',
+  apesProfileCwd: '作業ディレクトリ',
+  apesProfileNoCwd: '不明',
+  apesProfileRunning: '実行中',
+  apesProfileIdle: 'アイドル',
+  apesAppsNoFeed: 'この DSH バージョンはワークスペースアプリのデータ源を提供していません',
+  apesAppsWorkspace: 'ワークスペース',
+}
+
+/** Resolve the currently active DSH locale ('zh' | 'ja' | 'en' today). */
 export function attachApesLocale(service: { getSnapshot(): { active: string } } | undefined): void {
   apesLocaleService = service
 }
@@ -69,13 +119,14 @@ let apesLocaleService: { getSnapshot(): { active: string } } | undefined
 
 /**
  * Translate an apes key. Resolution order: active-locale chain (zh dict when
- * the DSH preference is zh, en dict otherwise) → key fallback (shows the key
- * itself rather than `undefined`). Mirrors the upstream t() minus the
- * better-locale override (Phase 2).
+ * the DSH preference is zh*, ja dict when it is ja*, en dict otherwise) → key
+ * fallback (shows the key itself rather than `undefined`). Mirrors the
+ * upstream t() minus the better-locale override (Phase 2).
  */
 export function t(key: ApesCopyKey, params?: Record<string, string | number>): string {
   const active = apesLocaleService?.getSnapshot().active ?? 'zh'
-  const dict = active.toLowerCase().startsWith('zh') ? apesZh : apesEn
+  const lang = active.toLowerCase()
+  const dict = lang.startsWith('zh') ? apesZh : lang.startsWith('ja') ? apesJa : apesEn
   let text: string | undefined = dict[key]
   if (text === undefined) text = key
   if (params !== undefined) {

src/client/apes/tabs.tsx

@@ -1,17 +1,27 @@
 /**
  * apes:* tab views (D2 = data wiring). Each tab reads live data from the
  * sessions list feed (`ctx.sessions.list`) via `useSyncExternalStore` and
- * reuses the fork's PURE lineage/job helpers — these are framework-free and
+ * reuses the fork's PURE lineage helpers — these are framework-free and
  * live outside `builtins/`, so importing them does not couple the apes module
  * to upstream UI and survives cherry-picks.
  *
- * Three information-layer tabs (C6: `apes:tasks` removed — it overlaps the
- * official DSH session tree in the native sidebar):
- *   - apes:agents  → the subagent topology rooted at the main agent of the
- *                    current session (rootAncestor + per-parent catalogs).
- *   - apes:apps    → no DSH host feed today: shows the workspace (cwd) of the
- *                    current session, otherwise an honest "no feed" note.
- *   - apes:profile → the current session's summary row (title, cwd, running).
+ * Five information-layer tabs (C7 reversal: `apes:tasks` is back). The reason
+ * the earlier C6 removal no longer holds: the native DSH session tree renders
+ * ONE focused lineage, while this panel is a *flat, whole-workspace* list with
+ * a running badge and an idle filter — complementary, not redundant.
+ *   - apes:tasks    → every session (running / current / subagent marks) with
+ *                     an idle filter; a running count badges the tab.
+ *   - apes:agents   → the subagent topology rooted at the main agent of the
+ *                     current session (rootAncestor + per-parent catalogs).
+ *   - apes:messages → honest placeholder: DSH exposes no message-stream feed.
+ *   - apes:apps     → no DSH host feed today: shows the workspace (cwd) of the
+ *                     current session, otherwise an honest "no feed" note.
+ *   - apes:profile  → the current session's summary row (title, cwd, running).
+ *
+ * Live-data discipline (C4): list-reading views subscribe only while the tab
+ * is on screen (`visible ? subscribe : NOOP_SUBSCRIBE`), so a collapsed panel
+ * stops re-rendering; tab-strip counts ride the cheap `badge` contract instead
+ * of a live subscription.
  *
  * Visual unity (C7): colors use the DSW design-token aliases
  * (`--dsw-alias-*`) so the apes panels match the native DSH sidebar
@@ -24,14 +34,19 @@
  *     `subscribe(cb)` is uSES-safe.
  *   - `scope.sessionId` = the currently-open session.
  */
-import { useCallback, useMemo, useState, type CSSProperties } from 'react'
+import { useCallback, useMemo, type CSSProperties } from 'react'
 import { useSyncExternalStore } from 'react'
-import { IconAgentOutline16, IconAppsOutline16, IconUserOutline16 } from './icons.tsx'
+import {
+  IconAgentOutline16,
+  IconAppsOutline16,
+  IconMessagesOutline16,
+  IconTasksOutline16,
+  IconUserOutline16,
+} from './icons.tsx'
 import type { TabComponentProps, TabDescriptor } from '../service.ts'
 import type {
   SidebarSessionList,
   SidebarSessionSummary,
-  SidebarSubagentCatalog,
   SidebarSubagentChildEntry,
 } from '../../context-types.ts'
 import { rootAncestor, isSideThreadSummary } from '../subagent-lineage.ts'
@@ -66,8 +81,16 @@ const S: Record<string, CSSProperties> = {
   cardLabel: { fontSize: 13, fontWeight: 500, flex: 1, minWidth: 0, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap', color: DSW.labelPrimary },
   cardSecondary: { fontSize: 11, color: DSW.labelSecondary, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' },
   badge: { fontSize: 11, color: DSW.labelTertiary, flexShrink: 0 },
+  chip: { fontSize: 10, lineHeight: '15px', padding: '0 6px', borderRadius: 999, border: `1px solid ${DSW.borderL2}`, color: DSW.labelSecondary, flexShrink: 0, whiteSpace: 'nowrap' },
+  taskRow: { appearance: 'none', textAlign: 'left', width: '100%', cursor: 'pointer', font: 'inherit', color: 'inherit' },
 }
 
+/** apes:tasks descriptor id (the plugin-toggle blob lives under this key). */
+export const TASKS_TAB_ID = 'apes:tasks'
+
+/** The plugin-local switch persisted in `pluginSettings['apes:tasks']`. */
+export const TASKS_SHOW_INACTIVE_KEY = 'showInactive'
+
 /** A small colored status dot (self-contained, not the builtin StateDot). */
 function Dot(props: { color: string }) {
   const style: CSSProperties = {
@@ -76,15 +99,91 @@ function Dot(props: { color: string }) {
   return <span aria-hidden style={style} />
 }
 
-/** Subscribe to the sessions list feed (uSES-safe). Returns the live snapshot. */
-function useSessionList(ctx: TabComponentProps['ctx']): SidebarSessionList {
-  const sessions = ctx.sessions
+/** A tiny status pill (current / running / subagent marks). */
+function Chip(props: { label: string; color?: string }) {
+  return <span style={props.color === undefined ? S.chip : { ...S.chip, color: props.color, borderColor: props.color }}>{props.label}</span>
+}
+
+/** Stable no-op subscription: `visible === false` pauses the feed. */
+export const NOOP_SUBSCRIBE = (): (() => void) => () => {}
+
+/**
+ * The subscription a view hands to uSES (C4 pause contract). Exported so the
+ * "hidden tab stops waking on session events" rule is unit-testable without a
+ * DOM: with `visible = false` the feed is never touched.
+ */
+export function feedSubscribe(
+  ctx: TabComponentProps['ctx'],
+  visible: boolean,
+): (callback: () => void) => () => void {
+  if (!visible) return NOOP_SUBSCRIBE
+  return callback => ctx.sessions.list.subscribe(callback)
+}
+
+/**
+ * Subscribe to the sessions list feed (uSES-safe). Returns the live snapshot.
+ * Pass `visible = false` to detach — a hidden tab keeps rendering from the
+ * last snapshot without waking on every session event.
+ */
+function useSessionList(ctx: TabComponentProps['ctx'], visible = true): SidebarSessionList {
+  const subscribe = useMemo(() => feedSubscribe(ctx, visible), [ctx, visible])
   return useSyncExternalStore(
-    useMemo(() => (callback: () => void) => sessions.list.subscribe(callback), [sessions]),
-    useCallback(() => sessions.list.getSnapshot(), [sessions]),
+    subscribe,
+    useCallback(() => ctx.sessions.list.getSnapshot(), [ctx]),
   )
 }
 
+/**
+ * The `showInactive` filter state. The declarative settings row writes it into
+ * the sidebar prefs document under `pluginSettings['apes:tasks']` (service
+ * contract, `SidebarSettingsDeclaration.pluginToggles`), which is NOT part of
+ * the public `SidebarPrefs` type — hence the narrow local cast. Default is
+ * true: the panel is a task list, so showing idle sessions is the useful
+ * default and the switch lets the reader trim it down.
+ */
+export function tasksShowInactive(store: TabComponentProps['store']): boolean {
+  try {
+    const prefs = store.getPrefs() as unknown as { pluginSettings?: Record<string, Record<string, unknown>> }
+    const blob = prefs.pluginSettings?.[TASKS_TAB_ID]
+    const value = blob?.[TASKS_SHOW_INACTIVE_KEY]
+    return typeof value === 'boolean' ? value : true
+  } catch {
+    return true
+  }
+}
+
+/**
+ * apes:tasks rows: every non-side-chat session, running ones first (then the
+ * current one), idle ones only when `showInactive`. PURE — unit-tested.
+ */
+export function tasksRows(list: SidebarSessionList, showInactive: boolean): SidebarSessionSummary[] {
+  const rows = Object.values(list.byId).filter(s => !isSideThreadSummary(s) && (showInactive || s.running === true))
+  const rank = (s: SidebarSessionSummary): number => (s.id === list.current ? 0 : s.running === true ? 1 : 2)
+  return rows.sort(
+    (a, b) => rank(a) - rank(b) || (a.displayTitle ?? a.id).localeCompare(b.displayTitle ?? b.id),
+  )
+}
+
+/** Running sessions (the tasks tab badge). Cheap: one pass, no allocation. */
+export function runningSessionCount(list: SidebarSessionList): number {
+  let count = 0
+  for (const s of Object.values(list.byId)) {
+    if (s.running === true && !isSideThreadSummary(s)) count += 1
+  }
+  return count
+}
+
+/** Subagents in the given session's tree (the agents tab badge). */
+export function subagentCount(list: SidebarSessionList, sessionId: string): number {
+  const root = rootAncestor(list.byId, sessionId)
+  let count = 0
+  for (const s of Object.values(list.byId)) {
+    if (s.origin !== 'subagent' || isSideThreadSummary(s)) continue
+    if (rootAncestor(list.byId, s.id) === root) count += 1
+  }
+  return count
+}
+
 /** One level of the subagent topology (rooted at the main agent). */
 function agentChildren(
   byId: Readonly<Record<string, SidebarSessionSummary>>,
@@ -95,9 +194,69 @@ function agentChildren(
   )
 }
 
+/** apes:tasks — the flat, whole-workspace session list. */
+export function ApesTasksView(props: TabComponentProps) {
+  const list = useSessionList(props.ctx, props.visible)
+  const store = props.store
+  const showInactive = useSyncExternalStore(
+    useMemo(() => (callback: () => void) => store.subscribe(callback), [store]),
+    useCallback(() => tasksShowInactive(store), [store]),
+  )
+  const rows = useMemo(() => tasksRows(list, showInactive), [list, showInactive])
+  const open = props.ctx.sessions.open
+
+  return (
+    <div style={S.body}>
+      <h2 style={S.title}>{t('apesTasksTitle')}</h2>
+      {rows.length === 0
+        ? <p style={S.hint}>{t('apesTasksEmpty')}</p>
+        : (
+          <div style={S.list}>
+            {rows.map(row => {
+              const running = row.running === true
+              return (
+                <button
+                  key={row.id}
+                  type="button"
+                  aria-current={row.id === list.current ? 'true' : undefined}
+                  title={row.displayTitle}
+                  onClick={() => { open?.(row.id) }}
+                  style={{ ...S.card, ...S.taskRow }}
+                >
+                  <div style={S.cardRow}>
+                    <Dot color={running ? DSW.success : DSW.labelTertiary} />
+                    <span style={S.cardLabel}>{row.displayTitle}</span>
+                    {row.id === list.current && <Chip label={t('apesTasksCurrent')} color={DSW.labelPrimary} />}
+                    {running && <Chip label={t('apesTasksRunning')} color={DSW.success} />}
+                    {row.origin === 'subagent' && <Chip label={t('apesTasksSubagent')} />}
+                  </div>
+                  {row.cwd !== undefined && (
+                    <div style={S.cardRow}>
+                      <span style={S.cardSecondary}>{row.cwd}</span>
+                    </div>
+                  )}
+                </button>
+              )
+            })}
+          </div>
+        )}
+    </div>
+  )
+}
+
+/** apes:messages — DSH exposes no message-stream feed; honest placeholder. */
+export function ApesMessagesView(_props: TabComponentProps) {
+  return (
+    <div style={S.body}>
+      <h2 style={S.title}>{t('apesMessagesTitle')}</h2>
+      <p style={S.hint}>{t('apesMessagesNoFeed')}</p>
+    </div>
+  )
+}
+
 /** apes:agents — the subagent topology of the current session's tree. */
 function ApesAgentsView(props: TabComponentProps) {
-  const list = useSessionList(props.ctx)
+  const list = useSessionList(props.ctx, props.visible)
   const { byId, subagentsByParent } = list
   const rootId = useMemo(() => rootAncestor(byId, props.scope.sessionId), [byId, props.scope.sessionId])
   const rootSummary = rootId === undefined ? undefined : byId[rootId]
@@ -165,7 +324,7 @@ function ApesAgentsView(props: TabComponentProps) {
 
 /** apes:profile — the current session's identity (title, cwd, running state). */
 export function ApesProfileView(props: TabComponentProps) {
-  const list = useSessionList(props.ctx)
+  const list = useSessionList(props.ctx, props.visible)
   const current = list.current
   const summary = current === undefined ? undefined : list.byId[current]
   const cwd = summary?.cwd ?? props.scope.cwd
@@ -202,7 +361,7 @@ export function ApesProfileView(props: TabComponentProps) {
 
 /** apes:apps — no DSH host feed today; shows the current workspace (cwd). */
 function ApesAppsView(props: TabComponentProps) {
-  const list = useSessionList(props.ctx)
+  const list = useSessionList(props.ctx, props.visible)
   const current = list.current
   const summary = current === undefined ? undefined : list.byId[current]
   const cwd = summary?.cwd ?? props.scope.cwd
@@ -224,14 +383,45 @@ function ApesAppsView(props: TabComponentProps) {
 }
 
 /**
- * The three apes:* tab descriptors (C6: `apes:tasks` removed — overlaps the
- * official DSH session tree). Order 901-903: agents/apps/profile. Each is
- * already shaped as `TabDescriptor` (component + single-instance + icon
- * element + i18n title function) so `registerApesTabs` can hand them straight
- * to `service.registerTab`. Information-layer tabs are single-instance.
+ * The five apes:* tab descriptors (C7: `apes:tasks` restored — the native
+ * session tree focuses one lineage, this list covers the whole workspace).
+ * Order 55-70 keeps them after the built-ins (editor 10 … browser 50) and in
+ * reading order: tasks / agents / apps / messages / profile. Each is already
+ * shaped as `TabDescriptor` (component + single-instance + icon element +
+ * i18n title function) so `registerApesTabs` can hand them straight to
+ * `service.registerTab`. Information-layer tabs are single-instance.
  */
 export const apesTabs: TabDescriptor[] = [
-  { id: 'apes:agents', title: () => t('apesAgentsTitle'), icon: (size: number) => <IconAgentOutline16 size={size} />, order: 60, single: true, component: ApesAgentsView },
+  {
+    id: TASKS_TAB_ID,
+    title: () => t('apesTasksTitle'),
+    icon: (size: number) => <IconTasksOutline16 size={size} />,
+    order: 55,
+    single: true,
+    component: ApesTasksView,
+    badge: ctx => {
+      const count = runningSessionCount(ctx.sessions.list.getSnapshot())
+      return count > 0 ? count : null
+    },
+    settings: {
+      pluginToggles: [
+        { key: TASKS_SHOW_INACTIVE_KEY, title: () => t('apesTasksShowInactive'), type: 'switch' },
+      ],
+    },
+  },
+  {
+    id: 'apes:agents',
+    title: () => t('apesAgentsTitle'),
+    icon: (size: number) => <IconAgentOutline16 size={size} />,
+    order: 60,
+    single: true,
+    component: ApesAgentsView,
+    badge: (ctx, scope) => {
+      const count = subagentCount(ctx.sessions.list.getSnapshot(), scope.sessionId)
+      return count > 0 ? count : null
+    },
+  },
   { id: 'apes:apps', title: () => t('apesAppsTitle'), icon: (size: number) => <IconAppsOutline16 size={size} />, order: 65, single: true, component: ApesAppsView },
+  { id: 'apes:messages', title: () => t('apesMessagesTitle'), icon: (size: number) => <IconMessagesOutline16 size={size} />, order: 67, single: true, component: ApesMessagesView },
   { id: 'apes:profile', title: () => t('apesProfileTitle'), icon: (size: number) => <IconUserOutline16 size={size} />, order: 70, single: true, component: ApesProfileView },
 ]

src/client/index.tsx

@@ -15,7 +15,7 @@ import { allLeaves, createSidebarStore, isAgentTabId } from './state.ts'
 import { createBetterSidebarService, matchUrlTarget } from './service.ts'
 import { revalidateChunksOnReactivate, setChunkModuleSystem } from './chunk-loader.ts'
 import { registerBuiltins } from './builtins/index.ts'
-import { registerApesTabs, APES_LOCALE_NS, apesZh, apesEn, attachApesLocale } from './apes/index.ts'
+import { registerApesTabs, APES_LOCALE_NS, apesZh, apesEn, apesJa, attachApesLocale } from './apes/index.ts'
 import { Sidebar } from './Sidebar.tsx'
 import { RenderBoundary } from './RenderBoundary.tsx'
 import { registerTurnTailInterception } from './intercept.tsx'
@@ -65,14 +65,16 @@ export function apply(ctx: Context): void {
   attachLocale(ctx.locale)
   // The apes module has its own locale namespace (isolated from the upstream
   // betterSidebar dicts): attach it so apes t() tracks the DSH active-locale
-  // preference, and register its zh/en dicts under `apes`.
+  // preference, and register its zh/ja/en dicts under `apes` (AGENTS §5: a ja
+  // dict must ship with every new zh key, else ja readers fall back to en).
   attachApesLocale(ctx.locale)
   ctx.effect(() => {
     const offZh = ctx.locale.register(LOCALE_NS, 'zh', zh)
     const offEn = ctx.locale.register(LOCALE_NS, 'en', en)
     const offApesZh = ctx.locale.register(APES_LOCALE_NS, 'zh', apesZh as Record<string, string>)
+    const offApesJa = ctx.locale.register(APES_LOCALE_NS, 'ja', apesJa as Record<string, string>)
     const offApesEn = ctx.locale.register(APES_LOCALE_NS, 'en', apesEn as Record<string, string>)
-    return () => { offZh(); offEn(); offApesZh(); offApesEn() }
+    return () => { offZh(); offEn(); offApesZh(); offApesJa(); offApesEn() }
   }, 'dsh-apes-sidebar: dictionaries')
 
   // Opt-in third-language support through @huanlin/dsh-plugin-better-locale.