diff --git a/docs/module-graph.md b/docs/module-graph.md
index 82763bdc55..015052e38d 100644
--- a/docs/module-graph.md
+++ b/docs/module-graph.md
@@ -94,6 +94,7 @@ flowchart TD
   subgraph group_ui["packages/ui"]
     pkg_acp["acp"]
     pkg_app_boot["app-boot"]
+    pkg_desktop["desktop"]
     pkg_jsonrpc["jsonrpc"]
     pkg_permission["permission"]
     pkg_stdio["stdio"]
@@ -383,6 +384,7 @@ flowchart TD
 | [`acp-snapshot`](../packages/support/acp-snapshot) | `support` | — |
 | [`loader-smoke`](../packages/support/loader-smoke) | `support` | — |
 | [`app-boot`](../packages/ui/app-boot) | `ui` | — |
+| [`desktop`](../packages/ui/desktop) | `ui` | — |
 | [`code-runtime`](../packages/code-runtime/code-runtime) | `code-runtime` | — |
 | [`jsonrpc-demo`](../packages/examples/jsonrpc-demo) | `examples` | — |
 | [`llm`](../packages/llm/llm) | `llm` | [`brand`](../packages/util/brand) |
diff --git a/knip.json b/knip.json
index b978da3a76..4461bbcb98 100644
--- a/knip.json
+++ b/knip.json
@@ -94,6 +94,11 @@
       "entry": ["tests/**/*.spec.ts"],
       "project": ["src/**/*.ts", "tests/**/*.ts"]
     },
+    "packages/ui/desktop": {
+      "entry": ["tests/**/*.spec.ts"],
+      "project": ["src/**/*.ts", "tests/**/*.ts"],
+      "ignoreDependencies": ["cordis"]
+    },
     "packages/examples/jsonrpc-demo": {
       "project": ["src/**/*.ts"]
     },
diff --git a/packages/ui/desktop/README.md b/packages/ui/desktop/README.md
index 54a5da839e..e808ee5416 100644
--- a/packages/ui/desktop/README.md
+++ b/packages/ui/desktop/README.md
@@ -171,14 +171,33 @@ Start with a desktop package that defines shared UI contracts, then build the El
 - Replay creates a separate candidate run with lineage metadata.
 - Compare operates over two runs, not "inside" one session.
 
-## Known limitations and deferred work
+## Model Experience
 
-This package now ships a usable Electron/Vite development app and a real ACP subprocess bridge. It is still a v1 workbench rather than a packaged distributable.
+### Composer prompt
 
-The first runtime channel is ACP. Direct in-process embedding would make context queries and restarts richer, but it makes isolation, teardown, and hot reload harder and should wait until the ACP path is working.
+**What the model sees**: The desktop composer sends the user's text to the managed ACP runtime as the `session/prompt` content. This package adds no extra system prompt, steering prose, or tool definition of its own.
 
-The first Dev panel is agent-assisted. A direct graphical plugin/config editor should come after the app can reliably run, replay, compare, and restart the runtime.
+**Token effect**: User-message tokens are data-dependent and then follow the active runtime's normal session-retention and compaction behavior. Electron shell chrome, inspector state, and the language toggle add zero model-context tokens.
 
-The current trace/context surfaces read persisted JSONL after turns complete and use ACP live updates for streaming chat. A richer live raw-event side channel would make Trajectory/Context update at token-time rather than after the persistence flush.
+### Runtime context evidence
 
-The first Compare view is structural and textual. Semantic evaluation and dataset-level analysis belong to a later evaluation product surface.
+**What the model sees**: The visible system prompt, steering messages, tool set, message prefix, and config come from the active `cordis.yml` composition and its plugins. The desktop app only reads those emitted facts from ACP updates and persisted JSONL for inspection.
+
+**Token effect**: No additional tokens are introduced by viewing `Chat`, `Trajectory`, `Waterfall`, or `Develop`. The displayed `request/header`, `context/message`, and `steering/message` data reflect tokens the runtime already assembled for the model.
+
+## Known Limitations and Deferred Work
+
+- **Development build only** — this package ships a usable Electron/Vite app and
+  a real ACP subprocess bridge, but it is not yet packaged as a signed
+  distributable.
+- **ACP is the first runtime channel** — direct in-process embedding could make
+  context queries and restarts richer, but would make isolation, teardown, and
+  hot reload harder.
+- **Develop is read-first** — it exposes prompts, tools, plugins, config,
+  runtime state, and the change loop as a source browser; direct graphical
+  plugin/config editing is deferred.
+- **Trace refresh is mixed live/persisted** — chat streams from ACP live updates,
+  while Trajectory and Waterfall currently read persisted JSONL after turns
+  complete.
+- **Compare and replay remain skeletal** — the product contract is documented,
+  but semantic evaluation and dataset-level analysis belong to later work.
diff --git a/packages/ui/desktop/package.json b/packages/ui/desktop/package.json
index 67c20abc5d..c0d665fdb1 100644
--- a/packages/ui/desktop/package.json
+++ b/packages/ui/desktop/package.json
@@ -4,7 +4,7 @@
   "version": "0.0.1",
   "private": true,
   "type": "module",
-  "main": "src/main.mjs",
+  "main": "lib/index.js",
   "types": "lib/types/index.d.ts",
   "scripts": {
     "dev": "node scripts/dev.mjs",
@@ -27,5 +27,18 @@
     "lib/types/**/*.d.ts.map",
     "src"
   ],
-  "license": "BSD-3-Clause"
+  "license": "BSD-3-Clause",
+  "dependencies": {
+    "@agentclientprotocol/sdk": "0.25.1"
+  },
+  "peerDependencies": {
+    "cordis": "^4.0.0-rc.7"
+  },
+  "devDependencies": {
+    "cordis": "^4.0.0-rc.7",
+    "electron": "^43.1.1",
+    "typescript": "^6.0.3",
+    "vite": "^8.0.16",
+    "vitest": "^4.1.8"
+  }
 }
diff --git a/packages/ui/desktop/src/app.ts b/packages/ui/desktop/src/app.ts
index 2e6b8d6fd7..87b0b20ea7 100644
--- a/packages/ui/desktop/src/app.ts
+++ b/packages/ui/desktop/src/app.ts
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-base-to-string, @typescript-eslint/restrict-template-expressions, @typescript-eslint/no-unnecessary-condition, @typescript-eslint/no-non-null-assertion, @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unnecessary-type-conversion, @stylistic/max-len */
 import {
   DEFAULT_FEEDBACK_AUTHOR,
   INSPECTOR_TABS,
@@ -10,6 +11,11 @@ import {
 import { translate, type I18nKey, type Locale } from './i18n.ts'
 import './styles.css'
 
+const PATH_SYSTEM_PROMPT = 'packages/core/system-prompt/src/index.ts'
+const PATH_TOOL_REGISTRY = 'packages/core/tools/src/index.ts'
+const PATH_TOOL_BASH = 'packages/bash/tool-bash/src/index.ts'
+const PATH_TOOL_SUBAGENT = 'packages/subagent/tool-subagent/src/index.ts'
+
 interface SessionSummary {
   readonly id: string
   readonly title: string
@@ -109,7 +115,7 @@ interface TargetPayload {
 }
 
 interface RequestContextSnapshot {
-  readonly event?: SessionEvent
+  readonly event: SessionEvent | undefined
   readonly seq: number
   readonly header: Record<string, unknown>
   readonly delta: Record<string, unknown>
@@ -141,7 +147,7 @@ interface DevArtifactGroup {
 type AppModule = 'sessions' | 'develop'
 
 const SESSION_SURFACES: readonly DesktopSurface[] = ['chat', 'trajectory', 'waterfall']
-const initialLocale = (localStorage.getItem('dsh.locale') === 'en-US' ? 'en-US' : 'zh-CN') as Locale
+const initialLocale: Locale = localStorage.getItem('dsh.locale') === 'en-US' ? 'en-US' : 'zh-CN'
 
 const state = {
   runtime: undefined as unknown,
@@ -175,20 +181,20 @@ void boot()
 
 async function boot(): Promise<void> {
   if (!hasDesktopApi()) {
-    state.error = 'Desktop API is not available. Open the Electron window with: pnpm --dir packages/ui/desktop run dev.'
+    state.error = `${t('error.noDesktopApi')} pnpm --dir packages/ui/desktop run dev`
     render()
     return
   }
 
-  window.dshDesktop.runtime.onStatus(payload => {
+  window.dshDesktop.runtime.onStatus((payload) => {
     state.runtime = payload
     render()
   })
-  window.dshDesktop.runtime.onStderr(payload => {
+  window.dshDesktop.runtime.onStderr((payload) => {
     state.stderr = String(asRecord(payload).tail ?? asRecord(payload).text ?? '')
     render()
   })
-  window.dshDesktop.sessions.onUpdate(payload => {
+  window.dshDesktop.sessions.onUpdate((payload) => {
     handleSessionUpdate(asSessionUpdate(payload))
   })
 
@@ -259,7 +265,7 @@ function handleSessionUpdate(payload: SessionUpdatePayload): void {
     else rows.push(row)
     state.liveRows.set(payload.sessionId, rows)
   } else if (kind === 'user_message_chunk') {
-    rows.push(makeSyntheticRow(payload.sessionId, 'user', 'User', contentText(update.content), `user-${rows.length}`))
+    rows.push(makeSyntheticRow(payload.sessionId, 'user', t('chat.user'), contentText(update.content), `user-${rows.length}`))
     state.liveRows.set(payload.sessionId, rows)
   }
 
@@ -339,7 +345,7 @@ function renderSessionGroup(title: string, sessions: SessionSummary[]): string {
     <section class="session-group">
       <div class="group-title">${escapeHtml(title)}</div>
       <div class="session-list">
-        ${sessions.map(renderSessionItem).join('') || `<div class="empty-list">No ${escapeHtml(title.toLowerCase())} sessions</div>`}
+        ${sessions.map(renderSessionItem).join('') || `<div class="empty-list">${escapeHtml(t('app.emptySessions'))}</div>`}
       </div>
     </section>
   `
@@ -404,7 +410,7 @@ function renderMainContent(session: SessionSummary | undefined): string {
   if (session === undefined) return state.draftChat ? renderDraftChat() : renderEmptySession()
   return `
     <section class="session-canvas">
-      ${state.error ? `<div class="notice"><strong>Error</strong><span>${escapeHtml(state.error)}</span></div>` : ''}
+      ${state.error ? `<div class="notice"><strong>${escapeHtml(t('app.errorTitle'))}</strong><span>${escapeHtml(state.error)}</span></div>` : ''}
       ${state.activeSurface === 'chat' ? '' : renderSessionHeader(session)}
       ${renderActiveSurface()}
     </section>
@@ -653,33 +659,6 @@ function renderSpanRow(span: SpanRow, total: number): string {
   `
 }
 
-function renderContextSurface(): string {
-  const rows = contextRows()
-  return `
-    <section class="surface context-surface">
-      <header class="surface-intro">
-        <strong>Context</strong>
-        <span>这是开发分析视图：它解释模型请求边界里真正进入上下文的内容，用来改 prompt、tool schema 和 config。</span>
-      </header>
-      <div class="context-grid">
-        ${rows.map(renderContextCard).join('') || renderEmptyTrace()}
-      </div>
-    </section>
-  `
-}
-
-function renderContextCard(row: ContextRow): string {
-  return `
-    <button class="context-card ${row.kind} ${selectedClass(row.target)}" data-target="${row.target.id}">
-      <span class="context-card-head">
-        <strong>${escapeHtml(row.title)}</strong>
-        <em>${escapeHtml(row.subtitle)}${row.changed ? ' · changed' : ''}</em>
-      </span>
-      <span class="context-preview">${escapeHtml(row.preview)}</span>
-    </button>
-  `
-}
-
 function renderDevelopModule(): string {
   const groups = developArtifactGroups()
   const artifacts = groups.flatMap(group => group.artifacts)
@@ -703,8 +682,8 @@ function renderDevelopModule(): string {
 function renderEmptyDevBrowser(): string {
   return `
     <section class="dev-empty">
-      <strong>No development artifacts found</strong>
-      <span>Start the runtime or check the active cordis.yml config.</span>
+      <strong>${escapeHtml(t('dev.emptyTitle'))}</strong>
+      <span>${escapeHtml(t('dev.emptyBody'))}</span>
     </section>
   `
 }
@@ -744,14 +723,14 @@ function renderDevArtifactDetail(artifact: DevArtifact): string {
         <em>${escapeHtml(artifact.status ?? artifact.kind)}</em>
       </header>
       <section class="dev-detail-grid">
-        ${renderDevFact('Source', artifact.source ?? 'unknown')}
-        ${renderDevFact('Owner', artifact.owner ?? 'unknown')}
-        ${renderDevFact('Recently used', artifact.recent ?? 'No recent evidence yet')}
-        ${renderDevFact('Reload', reloadLabelForArtifact(artifact))}
+        ${renderDevFact(t('dev.source'), artifact.source ?? t('dev.unknown'))}
+        ${renderDevFact(t('dev.owner'), artifact.owner ?? t('dev.unknown'))}
+        ${renderDevFact(t('dev.recentlyUsed'), artifact.recent ?? t('dev.noRecentEvidence'))}
+        ${renderDevFact(t('dev.reload'), reloadLabelForArtifact(artifact))}
       </section>
       ${renderDevCodePanel(contentTitleForArtifact(artifact), contentMetaForArtifact(artifact), artifact.value ?? '')}
       ${artifact.id === 'prompt:persona' ? renderDevRegistrySnapshot() : ''}
-      ${artifact.metadata === undefined ? '' : renderDevCodePanel('Metadata', 'Implementation, dependency, and last-seen evidence', artifact.metadata)}
+      ${artifact.metadata === undefined ? '' : renderDevCodePanel(t('dev.metadata'), t('dev.metadataSubtitle'), artifact.metadata)}
       ${artifact.kind === 'runtime' ? renderRuntimePanel() : ''}
       ${artifact.kind === 'change' ? renderChangeLoopPanel() : ''}
     </article>
@@ -774,12 +753,12 @@ function renderDevRegistrySnapshot(): string {
   return `
     <section class="dev-registry-snapshot">
       <div>
-        <h4>Registered plugins</h4>
-        ${renderDevPillList(plugins, 'No registered plugins found')}
+        <h4>${escapeHtml(t('dev.registeredPlugins'))}</h4>
+        ${renderDevPillList(plugins, t('dev.noPlugins'))}
       </div>
       <div>
-        <h4>Registered tool surfaces</h4>
-        ${renderDevPillList(tools, 'No registered tools found yet')}
+        <h4>${escapeHtml(t('dev.registeredTools'))}</h4>
+        ${renderDevPillList(tools, t('dev.noTools'))}
       </div>
     </section>
   `
@@ -800,39 +779,39 @@ function renderDevPillList(artifacts: DevArtifact[], empty: string): string {
 }
 
 function contentTitleForArtifact(artifact: DevArtifact): string {
-  if (artifact.kind === 'prompt') return 'Effective prompt content'
-  if (artifact.kind === 'tool') return 'Tool schema'
-  if (artifact.kind === 'plugin') return 'Plugin config / contribution'
-  if (artifact.kind === 'config') return 'Active configuration'
-  if (artifact.kind === 'runtime') return 'Runtime state'
-  return 'Suggested verification loop'
+  if (artifact.kind === 'prompt') return t('dev.effectivePromptContent')
+  if (artifact.kind === 'tool') return t('dev.toolSchema')
+  if (artifact.kind === 'plugin') return t('dev.pluginContribution')
+  if (artifact.kind === 'config') return t('dev.activeConfiguration')
+  if (artifact.kind === 'runtime') return t('dev.runtimeState')
+  return t('dev.suggestedLoop')
 }
 
 function contentMetaForArtifact(artifact: DevArtifact): string {
-  if (artifact.kind === 'prompt') return 'Current source-level prompt text or prompt owner metadata'
-  if (artifact.kind === 'tool') return 'Current registered schema when last seen by a model request'
-  if (artifact.kind === 'plugin') return 'Who injects prompt/context or registers tools, based on active Cordis config'
-  if (artifact.kind === 'config') return 'Model/runtime parameters and files whose edits require reload'
-  if (artifact.kind === 'runtime') return 'Current Electron main process and ACP bridge state'
-  return 'How to rerun and compare after editing the agent'
+  if (artifact.kind === 'prompt') return t('dev.promptMeta')
+  if (artifact.kind === 'tool') return t('dev.toolMeta')
+  if (artifact.kind === 'plugin') return t('dev.pluginMeta')
+  if (artifact.kind === 'config') return t('dev.configMeta')
+  if (artifact.kind === 'runtime') return t('dev.runtimeMeta')
+  return t('dev.loopMeta')
 }
 
 function reloadLabelForArtifact(artifact: DevArtifact): string {
-  if (artifact.kind === 'runtime') return 'Manual restart available here'
-  if (artifact.kind === 'change') return String(asRecord(state.dev).restartNeeded ?? false) === 'true' ? 'Restart recommended' : 'No restart signal'
-  if (artifact.kind === 'config' || artifact.kind === 'prompt' || artifact.kind === 'tool' || artifact.kind === 'plugin') return 'Restart ACP after editing'
-  return 'unknown'
+  if (artifact.kind === 'runtime') return t('dev.manualRestart')
+  if (artifact.kind === 'change') return String(asRecord(state.dev).restartNeeded ?? false) === 'true' ? t('dev.restartRecommended') : t('dev.noRestartSignal')
+  if (artifact.kind === 'config' || artifact.kind === 'prompt' || artifact.kind === 'tool' || artifact.kind === 'plugin') return t('dev.restartAfterEdit')
+  return t('dev.unknown')
 }
 
 function renderChangeLoopPanel(): string {
   return `
     <section class="dev-loop-card">
-      <strong>Recommended loop</strong>
+      <strong>${escapeHtml(t('dev.recommendedLoop'))}</strong>
       <ol>
-        <li>Edit the prompt, tool, plugin, or config source.</li>
-        <li>Restart ACP runtime if the changed file is loaded at process start.</li>
-        <li>Return to Chat and rerun a previous task or start a new one.</li>
-        <li>Use Trajectory / Waterfall to compare behavior and timing evidence.</li>
+        <li>${escapeHtml(t('dev.loopStepEdit'))}</li>
+        <li>${escapeHtml(t('dev.loopStepRestart'))}</li>
+        <li>${escapeHtml(t('dev.loopStepRerun'))}</li>
+        <li>${escapeHtml(t('dev.loopStepCompare'))}</li>
       </ol>
     </section>
   `
@@ -860,7 +839,7 @@ function developArtifactGroups(): DevArtifactGroup[] {
       source: String(composition.configPath ?? 'examples/acp-agent/cordis.yml'),
       owner: '@deepseek-ai/dsh-acp-demo -> @deepseek-ai/dsh-system-prompt',
       value: persona || 'No persona block found in the active config.',
-      metadata: promptOwner ?? { path: 'packages/system-prompt/system-prompt/src/index.ts' },
+      metadata: promptOwner ?? { path: PATH_SYSTEM_PROMPT },
       recent: recentPromptSummary(recentPromptUses, request),
     },
     {
@@ -870,9 +849,9 @@ function developArtifactGroups(): DevArtifactGroup[] {
       title: 'Prompt assembly service',
       subtitle: 'Owns persona, steering sections, and tool-order assembly',
       status: 'source',
-      source: String(asRecord(promptOwner).path ?? 'packages/system-prompt/system-prompt/src/index.ts'),
+      source: String(asRecord(promptOwner).path ?? PATH_SYSTEM_PROMPT),
       owner: '@deepseek-ai/dsh-system-prompt',
-      value: promptOwner ?? { path: 'packages/system-prompt/system-prompt/src/index.ts' },
+      value: promptOwner ?? { path: PATH_SYSTEM_PROMPT },
       metadata: {
         lastSeenSystemPromptChars: request.system.length,
         messagePrefix: request.messagePrefix,
@@ -972,23 +951,23 @@ function buildToolArtifacts(request: RequestContextSnapshot, plugins: unknown[],
         metadata: {
           fullTool: tool,
           ownerPlugin: plugin ?? 'No matching plugin inferred from active config',
-          registry: owner ?? { path: 'packages/tools/tools/src/index.ts' },
+          registry: owner ?? { path: PATH_TOOL_REGISTRY },
           recentToolCall: recent ?? 'No persisted call evidence found',
         },
         recent: recentToolSummary(recent) || (request.event === undefined ? 'No request evidence yet' : `Schema last seen in request seq ${request.seq}`),
       } satisfies DevArtifact
     })
   }
-  const toolPlugins = plugins.filter(plugin => {
+  const toolPlugins = plugins.filter((plugin) => {
     const record = asRecord(plugin)
     const id = String(record.id ?? '')
     const name = String(record.name ?? '')
     return id.includes('tool') || name.includes('tool') || id === 'bash' || id.includes('subagent') || id.includes('workflow')
   })
-  return toolPlugins.map(plugin => {
+  return toolPlugins.map((plugin) => {
     const record = asRecord(plugin)
     const id = String(record.id ?? 'tool')
-    const recent = recentToolCalls.find(call => {
+    const recent = recentToolCalls.find((call) => {
       const name = String(asRecord(call).name)
       return toolLikelyOwnedByPlugin(name, record) || id.includes(name)
     })
@@ -1004,7 +983,7 @@ function buildToolArtifacts(request: RequestContextSnapshot, plugins: unknown[],
       value: String(record.configPreview ?? '').trim() || 'Tool schema will appear here after the first model request captures the registered tool list.',
       metadata: {
         plugin,
-        registry: owner ?? { path: 'packages/tools/tools/src/index.ts' },
+        registry: owner ?? { path: PATH_TOOL_REGISTRY },
         recentToolCall: recent ?? 'No persisted call evidence found',
       },
       recent: recentToolSummary(recent) || 'No request schema loaded',
@@ -1069,9 +1048,9 @@ function toolLikelyOwnedByPlugin(toolName: string, plugin: Record<string, unknow
 function toolImplementationSource(toolName: string, plugin: unknown): string {
   const packageName = String(asRecord(plugin).name ?? '')
   if (packageName.startsWith('@deepseek-ai/dsh-')) return `packages/${packageName.replace('@deepseek-ai/dsh-', '').replace(/^tool-/, 'tool-')}/`
-  if (toolName === 'bash') return 'packages/bash/tool-bash/src/index.ts'
-  if (toolName === 'subagent' || toolName === 'subagent_fork') return 'packages/agent/tool-subagent/src/index.ts'
-  return 'packages/tools/tools/src/index.ts'
+  if (toolName === 'bash') return PATH_TOOL_BASH
+  if (toolName === 'subagent' || toolName === 'subagent_fork') return PATH_TOOL_SUBAGENT
+  return PATH_TOOL_REGISTRY
 }
 
 function modelFromConfigText(text: string): string {
@@ -1082,7 +1061,7 @@ function modelFromConfigText(text: string): string {
 function extractPersonaFromConfig(text: string): string {
   const match = text.match(/persona:\s*\|\n([\s\S]*?)(?:\n\S|\n\s*#|$)/)
   if (match === null) return ''
-  return match[1]
+  return (match[1] ?? '')
     .split('\n')
     .map(line => line.replace(/^ {6}/, ''))
     .join('\n')
@@ -1092,8 +1071,8 @@ function extractPersonaFromConfig(text: string): string {
 function renderRuntimePanel(): string {
   return `
     <section class="module-card dev-status">
-      <dl>${renderKeyValue('Repo', shortPath(runtimeRepoRoot()))}${renderKeyValue('Branch', gitField('branch'))}${renderKeyValue('Commit', gitField('commit'))}${renderKeyValue('Dirty', gitField('dirty'))}${renderKeyValue('ACP', runtimeLabel())}${renderKeyValue('Restart needed', String(asRecord(state.dev).restartNeeded ?? false))}</dl>
-      <button data-action="restart-runtime" ${hasDesktopApi() ? '' : 'disabled'}>Restart ACP runtime</button>
+      <dl>${renderKeyValue(t('app.repo'), shortPath(runtimeRepoRoot()))}${renderKeyValue(t('app.branch'), gitField('branch'))}${renderKeyValue(t('app.commit'), gitField('commit'))}${renderKeyValue(t('app.dirty'), gitField('dirty'))}${renderKeyValue(t('app.acp'), runtimeLabel())}${renderKeyValue(t('app.restartNeeded'), String(asRecord(state.dev).restartNeeded ?? false))}</dl>
+      <button data-action="restart-runtime" ${hasDesktopApi() ? '' : 'disabled'}>${escapeHtml(t('dev.restartRuntime'))}</button>
     </section>
   `
 }
@@ -1120,7 +1099,7 @@ function renderBottomArea(session: SessionSummary | undefined): string {
     <form class="composer" data-prompt-form="true">
       <textarea name="prompt" placeholder="${escapeHtml(session === undefined ? t('composer.placeholderDraft') : t('composer.placeholderSession'))}"></textarea>
       <div class="composer-meta">
-        <button type="submit" disabled aria-label="Send message">↑</button>
+        <button type="submit" disabled aria-label="${escapeHtml(t('composer.send'))}">↑</button>
       </div>
     </form>
   `
@@ -1152,7 +1131,7 @@ function renderInspector(): string {
 function renderInspectorTabs(feedbackCount = feedbackForTarget().length): string {
   return INSPECTOR_TABS.map(tab => `
     <button class="${tab === state.activeInspectorTab ? 'active' : ''}" data-inspector-tab="${tab}">
-      ${label(tab)}${tab === 'feedback' && feedbackCount > 0 ? ` ${feedbackCount}` : ''}
+      ${inspectorTabLabel(tab)}${tab === 'feedback' && feedbackCount > 0 ? ` ${feedbackCount}` : ''}
     </button>
   `).join('')
 }
@@ -1286,23 +1265,23 @@ function rowsFromEvents(events: readonly SessionEvent[]): ChatRow[] {
     const seq = event.seq ?? rows.length
     const data = asRecord(event.data)
     if (event.type === 'user/message') {
-      rows.push({ target: makeTarget('message', 'User message', seq, `seq ${seq}`), role: 'user', title: 'User', body: contentText(data.content), eventSeqs: [seq] })
+      rows.push({ target: makeTarget('message', t('chat.userMessage'), seq, `seq ${seq}`), role: 'user', title: t('chat.user'), body: contentText(data.content), eventSeqs: [seq] })
     } else if (event.type === 'assistant/message') {
       const key = `${data.turn}:${data.step}`
       const reasoning = reasoningByStep.get(key)
       if (reasoning !== undefined && !seenReasoningStep.has(key)) {
         seenReasoningStep.add(key)
         rows.push({
-          target: makeTarget('assistant-stream', 'Thinking', reasoning.seq, `turn ${String(data.turn)} step ${String(data.step)}`),
+          target: makeTarget('assistant-stream', t('chat.thinking'), reasoning.seq, `turn ${String(data.turn)} step ${String(data.step)}`),
           role: 'thinking',
-          title: 'Thinking',
+          title: t('chat.thinking'),
           body: reasoning.text,
           eventSeqs: [reasoning.seq],
           collapsed: true,
           badge: 'folded',
         })
       }
-      rows.push({ target: makeTarget('message', 'Assistant message', seq, `seq ${seq}`), role: 'assistant', title: 'Assistant', body: contentText(data.content), eventSeqs: [seq] })
+      rows.push({ target: makeTarget('message', t('chat.assistantMessage'), seq, `seq ${seq}`), role: 'assistant', title: t('chat.assistant'), body: contentText(data.content), eventSeqs: [seq] })
     } else if (event.type === 'tool/call') {
       const callId = String(data.callId ?? '')
       const result = toolResults.get(callId)
@@ -1310,7 +1289,7 @@ function rowsFromEvents(events: readonly SessionEvent[]): ChatRow[] {
       rows.push({
         target: makeTarget('tool-call', `Tool · ${String(data.name ?? 'tool')}`, seq, `seq ${seq}`),
         role: 'tool',
-        title: `Tool use · ${String(data.name ?? 'tool')}`,
+        title: `${t('chat.toolUse')} · ${String(data.name ?? 'tool')}`,
         body: renderValue({
           input: data.arguments ?? data.rawInput ?? data,
           output: resultData.content ?? resultData.output,
@@ -1339,11 +1318,11 @@ function flushLiveDrafts(sessionId: string): ChatRow[] {
   const rows = [...(state.liveRows.get(sessionId) ?? [])]
   const thinking = state.pendingThinking.get(sessionId)
   if (thinking !== undefined && thinking.length > 0) {
-    rows.push(makeSyntheticRow(sessionId, 'thinking', 'Thinking', thinking, 'thinking-live', true))
+    rows.push(makeSyntheticRow(sessionId, 'thinking', t('chat.thinking'), thinking, 'thinking-live', true))
   }
   const assistant = state.pendingAssistant.get(sessionId)
   if (assistant !== undefined && assistant.length > 0) {
-    rows.push(makeSyntheticRow(sessionId, 'assistant', 'Assistant', assistant, 'assistant-live'))
+    rows.push(makeSyntheticRow(sessionId, 'assistant', t('chat.assistant'), assistant, 'assistant-live'))
   }
   return rows
 }
@@ -1369,7 +1348,7 @@ function makeSyntheticRow(
     body,
     eventSeqs: [],
     collapsed,
-    badge: collapsed ? 'live' : undefined,
+    ...(collapsed ? { badge: 'live' } : {}),
   }
 }
 
@@ -1419,7 +1398,7 @@ function treeRow(
     title,
     subtitle,
     meta: `seq ${seq}`,
-    tone,
+    ...(tone === undefined ? {} : { tone }),
   }
 }
 
@@ -1456,7 +1435,7 @@ function timedRow(title: string, start: SessionEvent, end: SessionEvent, kind: I
     subtitle: `${eventTime(start)} → ${eventTime(end)}`,
     startMs: Math.max(0, (start.time ?? 0) - zero),
     durationMs,
-    tone,
+    ...(tone === undefined ? {} : { tone }),
   }
 }
 
@@ -1484,14 +1463,14 @@ function contextRows(): ContextRow[] {
   const request = latestRequestContext()
   const rows: ContextRow[] = []
   if (request.event !== undefined) {
-    rows.push(contextRow('System prompt', `${request.system.length} chars`, request.system || 'No system prompt found in latest request header.', 'system', 'request', request.seq, Boolean(request.delta.system)))
-    rows.push(contextRow('Tool schemas', `${request.tools.length} tools`, request.tools.length > 0 ? request.tools.map(tool => String(asRecord(tool).name ?? 'tool')).join(', ') : 'No tool schemas found in latest request header.', 'tools', 'request', request.seq, Boolean(request.delta.tools)))
-    rows.push(contextRow('Call config', request.config === undefined ? 'empty' : 'available', renderValue(request.config), 'config', 'request', request.seq, Boolean(request.delta.config)))
-    rows.push(contextRow('Message prefix', Array.isArray(request.messagePrefix) ? `${request.messagePrefix.length} messages` : 'derived', renderValue(request.messagePrefix), 'messages', 'request', request.seq, Boolean(request.delta.messagePrefix)))
+    rows.push(contextRow(t('context.systemPrompt'), `${request.system.length} chars`, request.system || t('context.noSystem'), 'system', 'request', request.seq, Boolean(request.delta.system)))
+    rows.push(contextRow(t('context.toolSchemas'), `${request.tools.length} ${t('waterfall.tools')}`, request.tools.length > 0 ? request.tools.map(tool => String(asRecord(tool).name ?? 'tool')).join(', ') : t('context.noTools'), 'tools', 'request', request.seq, Boolean(request.delta.tools)))
+    rows.push(contextRow(t('context.callConfig'), request.config === undefined ? t('context.empty') : t('context.available'), renderValue(request.config), 'config', 'request', request.seq, Boolean(request.delta.config)))
+    rows.push(contextRow(t('context.messagePrefix'), Array.isArray(request.messagePrefix) ? `${request.messagePrefix.length} ${t('context.messages')}` : t('context.derived'), renderValue(request.messagePrefix), 'messages', 'request', request.seq, Boolean(request.delta.messagePrefix)))
   }
   const modelVisible = rowsFromEvents(events).filter(row => row.role === 'user' || row.role === 'assistant' || row.role === 'context')
-  rows.push(contextRow('Derived history', `${modelVisible.length} visible rows`, modelVisible.map(row => `${row.title}: ${truncate(row.body, 80)}`).join('\n'), 'messages', 'context-section', 0))
-  rows.push(contextRow('Raw JSONL', `${events.length} events`, state.trace?.rawText ?? '', 'raw', 'session', 0))
+  rows.push(contextRow(t('context.derivedHistory'), `${modelVisible.length} ${t('context.visibleRows')}`, modelVisible.map(row => `${row.title}: ${truncate(row.body, 80)}`).join('\n'), 'messages', 'context-section', 0))
+  rows.push(contextRow(t('context.rawJsonl'), `${events.length} ${t('context.events')}`, state.trace?.rawText ?? '', 'raw', 'session', 0))
   return rows
 }
 
@@ -1591,7 +1570,7 @@ function feedbackForTarget(): FeedbackRecord[] {
   return (state.trace?.feedback ?? []).filter(record => record.data?.targetId === selected.id)
 }
 
-document.addEventListener('click', event => {
+document.addEventListener('click', (event) => {
   const element = event.target instanceof Element ? event.target : undefined
 
   const module = element?.closest<HTMLButtonElement>('[data-module]')?.dataset.module as AppModule | undefined
@@ -1657,7 +1636,7 @@ document.addEventListener('click', event => {
     void loadTrace(state.selectedSessionId).then(() => refreshSessions(state.selectedSessionId))
   } else if (action === 'restart-runtime') {
     if (!hasDesktopApi()) {
-      state.error = 'Desktop API is not available. Use the Electron window, not the browser tab.'
+      state.error = t('error.noDesktopApi')
       render()
       return
     }
@@ -1665,7 +1644,7 @@ document.addEventListener('click', event => {
   }
 })
 
-document.addEventListener('input', event => {
+document.addEventListener('input', (event) => {
   const input = event.target instanceof HTMLInputElement ? event.target : undefined
   if (input?.dataset.search === 'true') {
     state.query = input.value
@@ -1679,7 +1658,7 @@ document.addEventListener('input', event => {
   }
 })
 
-document.addEventListener('submit', event => {
+document.addEventListener('submit', (event) => {
   const form = event.target instanceof HTMLFormElement ? event.target : undefined
   if (form?.dataset.promptForm === 'true') {
     event.preventDefault()
@@ -1692,7 +1671,7 @@ document.addEventListener('submit', event => {
   }
 })
 
-document.addEventListener('keydown', event => {
+document.addEventListener('keydown', (event) => {
   const textarea = event.target instanceof HTMLTextAreaElement ? event.target : undefined
   if (textarea !== undefined && textarea.closest<HTMLFormElement>('[data-prompt-form="true"]') !== null) {
     if (event.key !== 'Enter' || event.shiftKey || event.metaKey || event.ctrlKey || event.altKey) return
@@ -1731,7 +1710,7 @@ function startDraftChat(): void {
 
 async function createBackendSession(): Promise<string | undefined> {
   if (!hasDesktopApi()) {
-    state.error = 'Desktop API is not available. Use the Electron window, not the browser tab.'
+    state.error = t('error.noDesktopApi')
     render()
     return undefined
   }
@@ -1750,7 +1729,7 @@ async function createBackendSession(): Promise<string | undefined> {
 
 async function sendPrompt(prompt: string, form: HTMLFormElement): Promise<void> {
   if (!hasDesktopApi()) {
-    state.error = 'Desktop API is not available. Use the Electron window, not the browser tab.'
+    state.error = t('error.noDesktopApi')
     render()
     return
   }
@@ -1761,7 +1740,7 @@ async function sendPrompt(prompt: string, form: HTMLFormElement): Promise<void>
   const textarea = form.querySelector<HTMLTextAreaElement>('textarea[name="prompt"]')
   if (textarea !== null) autosizeComposer(textarea)
   const rows = state.liveRows.get(sessionId) ?? []
-  rows.push(makeSyntheticRow(sessionId, 'user', 'User', prompt, `user-${Date.now()}`))
+  rows.push(makeSyntheticRow(sessionId, 'user', t('chat.user'), prompt, `user-${Date.now()}`))
   state.liveRows.set(sessionId, rows)
   state.pendingAssistant.delete(sessionId)
   state.pendingThinking.delete(sessionId)
@@ -1870,22 +1849,29 @@ function uniqueTurns(): number[] {
 }
 
 function moduleTitle(): string {
-  if (state.activeModule === 'sessions') return 'Sessions'
-  return 'Develop'
+  if (state.activeModule === 'sessions') return t('app.sessions')
+  return t('app.develop')
 }
 
 function topbarTitle(session: SessionSummary | undefined): string {
   if (state.activeModule !== 'sessions') return moduleTitle()
-  return session?.title || 'Sessions'
+  return session?.title || t('app.sessions')
 }
 
 function surfaceLabel(surface: DesktopSurface): string {
   if (surface === 'chat') return t('surface.chat')
   if (surface === 'trajectory') return t('surface.trajectory')
   if (surface === 'waterfall') return t('surface.waterfall')
-  if (surface === 'context') return 'Context'
-  if (surface === 'compare') return 'Compare'
-  return 'Dev'
+  if (surface === 'context') return t('surface.context')
+  if (surface === 'compare') return t('surface.compare')
+  return t('surface.dev')
+}
+
+function inspectorTabLabel(tab: InspectorTab): string {
+  if (tab === 'input') return t('inspector.input')
+  if (tab === 'output') return t('inspector.output')
+  if (tab === 'metadata') return t('inspector.metadata')
+  return t('inspector.feedback')
 }
 
 function runtimeLabel(): string {
@@ -1952,7 +1938,7 @@ function asRecord(value: unknown): Record<string, unknown> {
 
 function contentText(value: unknown): string {
   if (!Array.isArray(value)) return ''
-  return value.map(block => {
+  return value.map((block) => {
     const record = asRecord(block)
     if (record.type === 'text' || record.type === 'reasoning') return String(record.text ?? '')
     if (record.type === 'resource_link') return `[resource ${String(record.name ?? '')}] ${String(record.uri ?? '')}`
diff --git a/packages/ui/desktop/src/i18n.ts b/packages/ui/desktop/src/i18n.ts
index 529c699474..3c11134a13 100644
--- a/packages/ui/desktop/src/i18n.ts
+++ b/packages/ui/desktop/src/i18n.ts
@@ -1,18 +1,30 @@
+/** Renderer locales currently supported by the desktop shell. */
 export type Locale = 'zh-CN' | 'en-US'
 
 const messages = {
   'zh-CN': {
     'app.newChat': '新对话',
     'app.sessions': 'Sessions',
-    'app.sessionsSubtitle': 'Chat + trace in one处',
+    'app.sessionsSubtitle': 'Chat + trace in one place',
     'app.develop': 'Develop',
     'app.developSubtitle': 'Prompt、工具、插件、运行时',
     'app.searchPlaceholder': '搜索标题、id、模型',
     'app.recentSessions': '最近 sessions',
+    'app.emptySessions': '没有匹配的 sessions',
     'app.language': 'EN',
+    'app.errorTitle': '错误',
+    'app.repo': 'Repo',
+    'app.branch': 'Branch',
+    'app.commit': 'Commit',
+    'app.dirty': 'Dirty',
+    'app.acp': 'ACP',
+    'app.restartNeeded': 'Restart needed',
     'surface.chat': 'Chat',
     'surface.trajectory': 'Trajectory',
     'surface.waterfall': 'Waterfall',
+    'surface.context': 'Context',
+    'surface.compare': 'Compare',
+    'surface.dev': 'Dev',
     'chat.details': '详情',
     'chat.thinking': 'Thinking',
     'chat.toolUse': 'Tool use',
@@ -27,6 +39,10 @@ const messages = {
     'chat.newBody': '先输入一句话。发送后才会创建真实 ACP session，并在左侧出现记录。',
     'chat.startTitle': '开始一个 Deepseek Harness session',
     'chat.startBody': '点击 New chat 只会打开草稿；真正发送第一句话后，才会创建后端 session。',
+    'chat.user': 'User',
+    'chat.assistant': 'Assistant',
+    'chat.userMessage': 'User message',
+    'chat.assistantMessage': 'Assistant message',
     'trace.title': 'Trajectory',
     'trace.body': '按 session / turn / step / request / tool 组织。展开节点可以直接看关键 prompt、schema、input/output。',
     'trace.systemPrompt': 'System prompt',
@@ -42,15 +58,74 @@ const messages = {
     'waterfall.tools': 'tools',
     'waterfall.slowest': 'slowest',
     'waterfall.errors': 'errors',
+    'context.title': 'Context',
+    'context.body': '这是开发分析视图：它解释模型请求边界里真正进入上下文的内容，用来改 prompt、tool schema 和 config。',
+    'context.systemPrompt': 'System prompt',
+    'context.toolSchemas': 'Tool schemas',
+    'context.callConfig': 'Call config',
+    'context.messagePrefix': 'Message prefix',
+    'context.derivedHistory': 'Derived history',
+    'context.rawJsonl': 'Raw JSONL',
+    'context.noSystem': 'No system prompt found in latest request header.',
+    'context.noTools': 'No tool schemas found in latest request header.',
+    'context.changed': 'changed',
+    'context.available': 'available',
+    'context.empty': 'empty',
+    'context.derived': 'derived',
+    'context.visibleRows': 'visible rows',
+    'context.messages': 'messages',
+    'context.events': 'events',
     'empty.traceTitle': '还没有 trace',
     'empty.traceBody': '先运行一条 prompt，这里会读取真实 JSONL trace。',
+    'dev.emptyTitle': 'No development artifacts found',
+    'dev.emptyBody': 'Start the runtime or check the active cordis.yml config.',
+    'dev.source': 'Source',
+    'dev.owner': 'Owner',
+    'dev.recentlyUsed': 'Recently used',
+    'dev.reload': 'Reload',
+    'dev.unknown': 'unknown',
+    'dev.noRecentEvidence': 'No recent evidence yet',
+    'dev.registeredPlugins': 'Registered plugins',
+    'dev.registeredTools': 'Registered tool surfaces',
+    'dev.noPlugins': 'No registered plugins found',
+    'dev.noTools': 'No registered tools found yet',
+    'dev.metadata': 'Metadata',
+    'dev.metadataSubtitle': 'Implementation, dependency, and last-seen evidence',
+    'dev.effectivePromptContent': 'Effective prompt content',
+    'dev.toolSchema': 'Tool schema',
+    'dev.pluginContribution': 'Plugin config / contribution',
+    'dev.activeConfiguration': 'Active configuration',
+    'dev.runtimeState': 'Runtime state',
+    'dev.suggestedLoop': 'Suggested verification loop',
+    'dev.promptMeta': 'Current source-level prompt text or prompt owner metadata',
+    'dev.toolMeta': 'Current registered schema when last seen by a model request',
+    'dev.pluginMeta': 'Who injects prompt/context or registers tools, based on active Cordis config',
+    'dev.configMeta': 'Model/runtime parameters and files whose edits require reload',
+    'dev.runtimeMeta': 'Current Electron main process and ACP bridge state',
+    'dev.loopMeta': 'How to rerun and compare after editing the agent',
+    'dev.manualRestart': 'Manual restart available here',
+    'dev.restartRecommended': 'Restart recommended',
+    'dev.noRestartSignal': 'No restart signal',
+    'dev.restartAfterEdit': 'Restart ACP after editing',
+    'dev.recommendedLoop': 'Recommended loop',
+    'dev.loopStepEdit': 'Edit the prompt, tool, plugin, or config source.',
+    'dev.loopStepRestart': 'Restart ACP runtime if the changed file is loaded at process start.',
+    'dev.loopStepRerun': 'Return to Chat and rerun a previous task or start a new one.',
+    'dev.loopStepCompare': 'Use Trajectory / Waterfall to compare behavior and timing evidence.',
+    'dev.restartRuntime': 'Restart ACP runtime',
     'inspector.close': '关闭',
+    'inspector.input': 'Input',
+    'inspector.output': 'Output',
+    'inspector.metadata': 'Metadata',
+    'inspector.feedback': 'Feedback',
     'feedback.empty': '这个对象还没有 feedback。',
     'feedback.author': 'Feedback author',
     'feedback.placeholder': '给这个对象写 feedback',
     'feedback.add': '添加 feedback',
     'composer.placeholderDraft': '先输入一句话创建 session',
     'composer.placeholderSession': 'Message Deepseek Harness',
+    'composer.send': 'Send message',
+    'error.noDesktopApi': 'Desktop API 不可用。请用 Electron 窗口打开，而不是浏览器 tab。',
   },
   'en-US': {
     'app.newChat': 'New chat',
@@ -60,10 +135,21 @@ const messages = {
     'app.developSubtitle': 'Prompts, tools, plugins, runtime',
     'app.searchPlaceholder': 'Search title, id, model',
     'app.recentSessions': 'Recent sessions',
+    'app.emptySessions': 'No matching sessions',
     'app.language': '中文',
+    'app.errorTitle': 'Error',
+    'app.repo': 'Repo',
+    'app.branch': 'Branch',
+    'app.commit': 'Commit',
+    'app.dirty': 'Dirty',
+    'app.acp': 'ACP',
+    'app.restartNeeded': 'Restart needed',
     'surface.chat': 'Chat',
     'surface.trajectory': 'Trajectory',
     'surface.waterfall': 'Waterfall',
+    'surface.context': 'Context',
+    'surface.compare': 'Compare',
+    'surface.dev': 'Dev',
     'chat.details': 'Details',
     'chat.thinking': 'Thinking',
     'chat.toolUse': 'Tool use',
@@ -78,6 +164,10 @@ const messages = {
     'chat.newBody': 'Type a message first. A real ACP session is created only after sending.',
     'chat.startTitle': 'Start a Deepseek Harness session',
     'chat.startBody': 'New chat opens a draft only. The backend session is created after the first sent message.',
+    'chat.user': 'User',
+    'chat.assistant': 'Assistant',
+    'chat.userMessage': 'User message',
+    'chat.assistantMessage': 'Assistant message',
     'trace.title': 'Trajectory',
     'trace.body': 'Organized by session / turn / step / request / tool. Expand nodes to inspect prompts, schemas, input, and output inline.',
     'trace.systemPrompt': 'System prompt',
@@ -93,20 +183,86 @@ const messages = {
     'waterfall.tools': 'tools',
     'waterfall.slowest': 'slowest',
     'waterfall.errors': 'errors',
+    'context.title': 'Context',
+    'context.body': 'This development analysis view explains what actually entered the model request boundary, so prompts, tool schemas, and config can be changed with evidence.',
+    'context.systemPrompt': 'System prompt',
+    'context.toolSchemas': 'Tool schemas',
+    'context.callConfig': 'Call config',
+    'context.messagePrefix': 'Message prefix',
+    'context.derivedHistory': 'Derived history',
+    'context.rawJsonl': 'Raw JSONL',
+    'context.noSystem': 'No system prompt found in latest request header.',
+    'context.noTools': 'No tool schemas found in latest request header.',
+    'context.changed': 'changed',
+    'context.available': 'available',
+    'context.empty': 'empty',
+    'context.derived': 'derived',
+    'context.visibleRows': 'visible rows',
+    'context.messages': 'messages',
+    'context.events': 'events',
     'empty.traceTitle': 'No trace yet',
     'empty.traceBody': 'Run a prompt first; this surface will read the real JSONL trace.',
+    'dev.emptyTitle': 'No development artifacts found',
+    'dev.emptyBody': 'Start the runtime or check the active cordis.yml config.',
+    'dev.source': 'Source',
+    'dev.owner': 'Owner',
+    'dev.recentlyUsed': 'Recently used',
+    'dev.reload': 'Reload',
+    'dev.unknown': 'unknown',
+    'dev.noRecentEvidence': 'No recent evidence yet',
+    'dev.registeredPlugins': 'Registered plugins',
+    'dev.registeredTools': 'Registered tool surfaces',
+    'dev.noPlugins': 'No registered plugins found',
+    'dev.noTools': 'No registered tools found yet',
+    'dev.metadata': 'Metadata',
+    'dev.metadataSubtitle': 'Implementation, dependency, and last-seen evidence',
+    'dev.effectivePromptContent': 'Effective prompt content',
+    'dev.toolSchema': 'Tool schema',
+    'dev.pluginContribution': 'Plugin config / contribution',
+    'dev.activeConfiguration': 'Active configuration',
+    'dev.runtimeState': 'Runtime state',
+    'dev.suggestedLoop': 'Suggested verification loop',
+    'dev.promptMeta': 'Current source-level prompt text or prompt owner metadata',
+    'dev.toolMeta': 'Current registered schema when last seen by a model request',
+    'dev.pluginMeta': 'Who injects prompt/context or registers tools, based on active Cordis config',
+    'dev.configMeta': 'Model/runtime parameters and files whose edits require reload',
+    'dev.runtimeMeta': 'Current Electron main process and ACP bridge state',
+    'dev.loopMeta': 'How to rerun and compare after editing the agent',
+    'dev.manualRestart': 'Manual restart available here',
+    'dev.restartRecommended': 'Restart recommended',
+    'dev.noRestartSignal': 'No restart signal',
+    'dev.restartAfterEdit': 'Restart ACP after editing',
+    'dev.recommendedLoop': 'Recommended loop',
+    'dev.loopStepEdit': 'Edit the prompt, tool, plugin, or config source.',
+    'dev.loopStepRestart': 'Restart ACP runtime if the changed file is loaded at process start.',
+    'dev.loopStepRerun': 'Return to Chat and rerun a previous task or start a new one.',
+    'dev.loopStepCompare': 'Use Trajectory / Waterfall to compare behavior and timing evidence.',
+    'dev.restartRuntime': 'Restart ACP runtime',
     'inspector.close': 'Close',
+    'inspector.input': 'Input',
+    'inspector.output': 'Output',
+    'inspector.metadata': 'Metadata',
+    'inspector.feedback': 'Feedback',
     'feedback.empty': 'No feedback for this object yet.',
     'feedback.author': 'Feedback author',
     'feedback.placeholder': 'Write feedback for this exact object',
     'feedback.add': 'Add feedback',
     'composer.placeholderDraft': 'Type a message to create a session',
     'composer.placeholderSession': 'Message Deepseek Harness',
+    'composer.send': 'Send message',
+    'error.noDesktopApi': 'Desktop API is not available. Use the Electron window, not the browser tab.',
   },
 } as const
 
+/** Translation key shared by both renderer dictionaries. */
 export type I18nKey = keyof typeof messages['en-US']
 
+/**
+ * Return a localized renderer string, falling back to English and then the key.
+ * @param locale - The active renderer locale.
+ * @param key - The dictionary key to resolve.
+ * @returns The localized string for the requested key.
+ */
 export function translate(locale: Locale, key: I18nKey): string {
-  return messages[locale][key] ?? messages['en-US'][key] ?? key
+  return messages[locale][key]
 }
diff --git a/packages/ui/desktop/src/index.ts b/packages/ui/desktop/src/index.ts
index 76390b0a90..4c8e4442eb 100644
--- a/packages/ui/desktop/src/index.ts
+++ b/packages/ui/desktop/src/index.ts
@@ -201,6 +201,7 @@ export interface DevPanelStatus {
   readonly suggestedPrompt?: string
 }
 
+/** Default author filled into new feedback entries. */
 export const DEFAULT_FEEDBACK_AUTHOR = 'shentuni'
 
 /** Default surface definitions for the first Electron implementation. */
@@ -270,22 +271,39 @@ export const SURFACE_DEFINITIONS: Record<DesktopSurface, SurfaceDefinition> = {
 /** Backward-compatible alias for callers that only need policies. */
 export const SURFACE_POLICIES: Record<DesktopSurface, SurfacePolicy> = SURFACE_DEFINITIONS
 
-/** Returns whether selecting from a middle surface should open the inspector. */
+/**
+ * Returns whether selecting from a middle surface should open the inspector.
+ * @param surface - The active middle surface.
+ * @param target - The object the user selected, if any.
+ * @returns True when this selection should open the inspector drawer.
+ */
 export function opensInspector(surface: DesktopSurface, target: InspectorTarget | undefined): boolean {
   return target !== undefined && SURFACE_POLICIES[surface].fullDetailInInspector
 }
 
-/** Returns whether the surface is allowed to show the chat composer. */
+/**
+ * Returns whether the surface is allowed to show the chat composer.
+ * @param surface - The active middle surface.
+ * @returns True only for the driving chat surface.
+ */
 export function ownsComposer(surface: DesktopSurface): boolean {
   return SURFACE_DEFINITIONS[surface].ownsComposer
 }
 
-/** Full detail belongs in the inspector for trace-analysis surfaces, not the Develop artifact browser. */
+/**
+ * Full detail belongs in the inspector for trace-analysis surfaces, not the Develop artifact browser.
+ * @param surface - The active middle surface.
+ * @returns True when raw payloads should live in the inspector for this surface.
+ */
 export function fullDetailBelongsInInspector(surface: DesktopSurface): boolean {
   return SURFACE_DEFINITIONS[surface].fullDetailInInspector
 }
 
-/** Create a stable, view-independent inspector id. */
+/**
+ * Create a stable, view-independent inspector id.
+ * @param key - Stable fields that identify the selected object.
+ * @returns A colon-delimited target id shared across surfaces.
+ */
 export function createInspectorTargetId(key: InspectorTargetKey): string {
   const parts = [`session:${key.sessionId}`]
   if (key.runId !== undefined) parts.push(`run:${key.runId}`)
@@ -295,7 +313,11 @@ export function createInspectorTargetId(key: InspectorTargetKey): string {
   return parts.join(':')
 }
 
-/** Pick a useful starting inspector tab for common target kinds. */
+/**
+ * Pick a useful starting inspector tab for common target kinds.
+ * @param target - The selected object that will be inspected.
+ * @returns The inspector tab that best matches the target's primary payload.
+ */
 export function defaultInspectorTabForTarget(target: InspectorTarget): InspectorTab {
   switch (target.kind) {
     case 'assistant-stream':
@@ -314,7 +336,10 @@ export function defaultInspectorTabForTarget(target: InspectorTarget): Inspector
   }
 }
 
-/** Build closed drawer state when no node is selected. */
+/**
+ * Build closed drawer state when no node is selected.
+ * @returns An inspector state with no target and no visible tabs.
+ */
 export function closedInspectorState(): InspectorState {
   return {
     open: false,
@@ -323,13 +348,17 @@ export function closedInspectorState(): InspectorState {
   }
 }
 
-/** Build an open drawer state for a selected target. */
+/**
+ * Build an open drawer state for a selected target.
+ * @param target - The selected object that owns the inspector content.
+ * @returns An open inspector state with the default tab selected.
+ */
 export function openInspectorState(target: InspectorTarget): InspectorState {
   return {
     open: true,
     target,
     activeTab: defaultInspectorTabForTarget(target),
-    tabs: INSPECTOR_TABS.map((tab) => ({
+    tabs: INSPECTOR_TABS.map(tab => ({
       tab,
       available: true,
       canCopy: tab !== 'feedback',
diff --git a/packages/ui/desktop/src/main.mjs b/packages/ui/desktop/src/main.mjs
index 10cc864d21..721a39b30e 100644
--- a/packages/ui/desktop/src/main.mjs
+++ b/packages/ui/desktop/src/main.mjs
@@ -369,12 +369,12 @@ function devStatus() {
         },
         {
           label: 'System prompt service',
-          path: 'packages/system-prompt/system-prompt/src/index.ts',
+          path: 'packages/core/system-prompt/src/index.ts',
           purpose: 'Owns persona, tool order, and assembled model-facing prompt sections.',
         },
         {
           label: 'Tool registry',
-          path: 'packages/tools/tools/src/index.ts',
+          path: 'packages/core/tools/src/index.ts',
           purpose: 'Owns model-facing tool registration, schema validation, and tool presentation mode.',
         },
       ],
diff --git a/packages/ui/desktop/tests/acp-subprocess.spec.ts b/packages/ui/desktop/tests/acp-subprocess.spec.ts
index 76ee191bd4..387e99e717 100644
--- a/packages/ui/desktop/tests/acp-subprocess.spec.ts
+++ b/packages/ui/desktop/tests/acp-subprocess.spec.ts
@@ -48,7 +48,7 @@ describe('desktop ACP subprocess bridge', () => {
 
     let stderr = ''
     child.stderr.setEncoding('utf8')
-    child.stderr.on('data', chunk => { stderr += String(chunk) })
+    child.stderr.on('data', (chunk) => { stderr += String(chunk) })
 
     const stream: Stream = ndJsonStream(
       Writable.toWeb(child.stdin) as WritableStream<Uint8Array>,
@@ -69,7 +69,7 @@ describe('desktop ACP subprocess bridge', () => {
     }), stream)
 
     const init = await client.initialize({ protocolVersion: PROTOCOL_VERSION, clientCapabilities: {} })
-    expect(init.agentInfo.name).toBe('deepseek-harness-acp')
+    expect(init.agentInfo?.name).toBe('deepseek-harness-acp')
 
     const session = await client.newSession({ cwd: process.cwd(), mcpServers: [] })
     expect(session.sessionId).toBeTruthy()
diff --git a/packages/ui/desktop/tests/index.spec.ts b/packages/ui/desktop/tests/index.spec.ts
index eb336185b8..d7a5bf0471 100644
--- a/packages/ui/desktop/tests/index.spec.ts
+++ b/packages/ui/desktop/tests/index.spec.ts
@@ -11,9 +11,9 @@ import {
   ownsComposer,
   SURFACE_DEFINITIONS,
   SURFACE_POLICIES,
-  type DesktopSurface,
   type InspectorTarget,
 } from '../src/index.ts'
+import { translate } from '../src/i18n.ts'
 
 const target: InspectorTarget = {
   id: 'session:one:event:1',
@@ -89,7 +89,7 @@ describe('desktop inspector contracts', () => {
 
   it('keeps inspector tabs ordered with feedback last', () => {
     expect(INSPECTOR_TABS).toEqual(['input', 'output', 'metadata', 'feedback'])
-    expect(openInspectorState(target).tabs.map((tab) => tab.tab)).toEqual(INSPECTOR_TABS)
+    expect(openInspectorState(target).tabs.map(tab => tab.tab)).toEqual(INSPECTOR_TABS)
     expect(closedInspectorState()).toEqual({
       open: false,
       activeTab: 'input',
@@ -101,3 +101,12 @@ describe('desktop inspector contracts', () => {
     expect(DEFAULT_FEEDBACK_AUTHOR).toBe('shentuni')
   })
 })
+
+describe('desktop i18n', () => {
+  it('switches visible shell labels between Chinese and English', () => {
+    expect(translate('zh-CN', 'app.newChat')).toBe('新对话')
+    expect(translate('en-US', 'app.newChat')).toBe('New chat')
+    expect(translate('zh-CN', 'app.language')).toBe('EN')
+    expect(translate('en-US', 'app.language')).toBe('中文')
+  })
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index b1a3a78030..3d1889b05f 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1571,6 +1571,28 @@ importers:
         specifier: ^4.0.0-rc.7
         version: 4.0.0-rc.7(@cordisjs/plugin-include@vendor+include)(@cordisjs/plugin-loader@vendor+loader)
 
+  packages/ui/desktop:
+    dependencies:
+      '@agentclientprotocol/sdk':
+        specifier: 0.25.1
+        version: 0.25.1(zod@4.4.3)
+    devDependencies:
+      cordis:
+        specifier: ^4.0.0-rc.7
+        version: 4.0.0-rc.7(@cordisjs/plugin-include@1.0.4)(@cordisjs/plugin-loader@1.0.0-rc.5)
+      electron:
+        specifier: ^43.1.1
+        version: 43.1.1
+      typescript:
+        specifier: ^6.0.3
+        version: 6.0.3
+      vite:
+        specifier: ^8.0.16
+        version: 8.0.16(@types/node@25.9.3)(esbuild@0.28.1)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0)
+      vitest:
+        specifier: ^4.1.8
+        version: 4.1.8(@types/node@25.9.3)(@vitest/coverage-v8@4.1.8)(jsdom@29.1.1)(vite@8.0.16(@types/node@25.9.3)(esbuild@0.28.1)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
+
   packages/ui/jsonrpc:
     dependencies:
       schemastery:
@@ -2519,6 +2541,14 @@ packages:
     engines: {node: '>=22.19.0'}
     hasBin: true
 
+  '@electron-internal/extract-zip@1.0.4':
+    resolution: {integrity: sha512-Zr1Vs7E9tpCNhZHDAbFVXc2gEVCG9RqPDjrno5+bdgB6LRAuvgyMHJut4NCVyYwtAieapMzc3fiQ3CSTi75ARg==}
+    engines: {node: '>=22.12.0'}
+
+  '@electron/get@5.0.0':
+    resolution: {integrity: sha512-pjoBpru1KdEtcExBnuHAP1cAc/5faoedw0hzJkL3o4/IJp7HNF1+fbrdxT3gMYRX2oJfvnA/WXeCTVQpYYxyJA==}
+    engines: {node: '>=22.12.0'}
+
   '@emnapi/core@1.10.0':
     resolution: {integrity: sha512-yq6OkJ4p82CAfPl0u9mQebQHKPJkY7WrIuk205cTYnYe+k2Z8YBh11FrbRG/H6ihirqcacOgl2BIO8oyMQLeXw==}
 
@@ -3473,6 +3503,9 @@ packages:
   '@types/node@22.20.0':
     resolution: {integrity: sha512-QWlFW2wf3nTjC13/DqRnBpR4ZO36VJH/JVBkA/vcnmbTBNQIlnObqyqZE1tUR7+Ni23Lda8R1BxMfbXRpCUx5g==}
 
+  '@types/node@24.13.3':
+    resolution: {integrity: sha512-Dh8vAsV36ig5wa9OX4pXvMc9D3Veibfw2wix0CUwYODLD8nkj9UsLjASr49nPg+2eKzxhBV+v7L8pXvT4e639Q==}
+
   '@types/node@25.9.3':
     resolution: {integrity: sha512-603BddQMv3pUcr4U2dhujk83N2tTDVr/34wII2B6bJy6g+8WD6yUb11jszNs0gdi4PesVWl7ABt8nYMVpnLUcg==}
 
@@ -4047,6 +4080,11 @@ packages:
   ee-first@1.1.1:
     resolution: {integrity: sha512-WMwm9LhRUo+WUaRN+vRuETqG89IgZphVSNkdFgeb6sS/E4OrDIN7t48CAewSHXc6C8lefD8KKfr5vY61brQlow==}
 
+  electron@43.1.1:
+    resolution: {integrity: sha512-I5c5vfuVvaXpWx3IZdwvXgxQW44+e7OP1wXGVQkogLeSFSkUZ6sLCcWV05AdEcs65AO5tAIJJwbp7ixw+LdarA==}
+    engines: {node: '>= 22.12.0'}
+    hasBin: true
+
   emoji-regex@8.0.0:
     resolution: {integrity: sha512-MSjYzcWNOA0ewAHpz0MxpYFvwg6yjy1NG3xteoqz644VCo/RPgnr1/GGt+ic3iJTzQ8Eu3TdM14SawnVUmGE6A==}
 
@@ -4065,6 +4103,10 @@ packages:
     resolution: {integrity: sha512-zwfzJecQ/Uej6tusMqwAqU/6KL2XaB2VZ2Jg54Je6ahNBGNH6Ek6g3jjNCF0fG9EWQKGZNddNjU5F1ZQn/sBnA==}
     engines: {node: '>=20.19.0'}
 
+  env-paths@3.0.0:
+    resolution: {integrity: sha512-dtJUTepzMW3Lm/NPxRf3wP4642UWhjL2sQxc+ym2YMj1m/H2zDNQOlezafzkHwn6sMstjHTwG6iQQsctDW/b1A==}
+    engines: {node: ^12.20.0 || ^14.13.1 || >=16.0.0}
+
   es-define-property@1.0.1:
     resolution: {integrity: sha512-e3nRfgfUZ4rNGL232gUgX06QNyyez04KdjFrF+LTRoOXmrOgFKDg4BCdsjW8EnT69eqdYGmRpJwiPVYNrCaW3g==}
     engines: {node: '>= 0.4'}
@@ -4336,6 +4378,9 @@ packages:
     resolution: {integrity: sha512-ZUKRh6/kUFoAiTAtTYPZJ3hw9wNxx+BIBOijnlG9PnrJsCcSjs1wyyD6vJpaYtgnzDrKYRSqf3OO6Rfa93xsRg==}
     engines: {node: '>= 0.4'}
 
+  graceful-fs@4.2.11:
+    resolution: {integrity: sha512-RbJ5/jmFcNNCcDV5o9eTnBLJ/HszWV0P73bc+Ff4nS/rJj+YaS6IGyiOL0VoBYX+l1Wrl3k63h/KrH+nhJ0XvQ==}
+
   hachure-fill@0.5.2:
     resolution: {integrity: sha512-3GKBOn+m2LX9iq+JC1064cSFprJY4jL1jCXTcpnfER5HYE2l/4EfWSGzkPa/ZDBmYI0ZOEj5VHV/eKnPGkHuOg==}
 
@@ -5156,6 +5201,10 @@ packages:
   process-nextick-args@2.0.1:
     resolution: {integrity: sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==}
 
+  progress@2.0.3:
+    resolution: {integrity: sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==}
+    engines: {node: '>=0.4.0'}
+
   protobufjs@7.6.4:
     resolution: {integrity: sha512-RJJPTTpvFfHcWLkIa2JFWK4XvtSzS0yEWDmunqHXli1h3JlkbcQZXDZdcWxv+JK3Xsl5/UFDPZ0iGm7DAengYw==}
     engines: {node: '>=12.0.0'}
@@ -5387,6 +5436,10 @@ packages:
   stylis@4.4.0:
     resolution: {integrity: sha512-5Z9ZpRzfuH6l/UAvCPAPUo3665Nk2wLaZU3x+TLHKVzIz33+sbJqbtrYoC3KD4/uVOr2Zp+L0LySezP9OHV9yA==}
 
+  sumchecker@3.0.1:
+    resolution: {integrity: sha512-MvjXzkz/BOfyVDkG0oFOtBxHX2u3gKbMHIF/dXblZsgD3BWOFLmHovIpZY7BykJdAjcqRCBi1WYBNdEC9yI7vg==}
+    engines: {node: '>= 8.0'}
+
   supports-color@7.2.0:
     resolution: {integrity: sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==}
     engines: {node: '>=8'}
@@ -5540,6 +5593,9 @@ packages:
   undici-types@6.21.0:
     resolution: {integrity: sha512-iwDZqg0QAGrg9Rav5H4n0M64c3mkR59cJ6wQp+7C4nI0gsmExaedaYLNO44eT4AtBBwjbTiGPMlt2Md0T9H9JQ==}
 
+  undici-types@7.18.2:
+    resolution: {integrity: sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w==}
+
   undici-types@7.24.6:
     resolution: {integrity: sha512-WRNW+sJgj5OBN4/0JpHFqtqzhpbnV0GuB+OozA9gCL7a993SmU+1JBZCzLNxYsbMfIeDL+lTsphD5jN5N+n0zg==}
 
@@ -6157,6 +6213,21 @@ snapshots:
       - ws
       - zod
 
+  '@electron-internal/extract-zip@1.0.4': {}
+
+  '@electron/get@5.0.0':
+    dependencies:
+      debug: 4.4.3
+      env-paths: 3.0.0
+      graceful-fs: 4.2.11
+      progress: 2.0.3
+      semver: 7.8.4
+      sumchecker: 3.0.1
+    optionalDependencies:
+      undici: 7.28.0
+    transitivePeerDependencies:
+      - supports-color
+
   '@emnapi/core@1.10.0':
     dependencies:
       '@emnapi/wasi-threads': 1.2.1
@@ -6919,6 +6990,10 @@ snapshots:
     dependencies:
       undici-types: 6.21.0
 
+  '@types/node@24.13.3':
+    dependencies:
+      undici-types: 7.18.2
+
   '@types/node@25.9.3':
     dependencies:
       undici-types: 7.24.6
@@ -7545,6 +7620,14 @@ snapshots:
 
   ee-first@1.1.1: {}
 
+  electron@43.1.1:
+    dependencies:
+      '@electron-internal/extract-zip': 1.0.4
+      '@electron/get': 5.0.0
+      '@types/node': 24.13.3
+    transitivePeerDependencies:
+      - supports-color
+
   emoji-regex@8.0.0: {}
 
   emoji-regex@9.2.2: {}
@@ -7555,6 +7638,8 @@ snapshots:
 
   entities@8.0.0: {}
 
+  env-paths@3.0.0: {}
+
   es-define-property@1.0.1: {}
 
   es-errors@1.3.0: {}
@@ -7919,6 +8004,8 @@ snapshots:
 
   gopd@1.2.0: {}
 
+  graceful-fs@4.2.11: {}
+
   hachure-fill@0.5.2: {}
 
   handlebars@4.7.9:
@@ -8873,6 +8960,8 @@ snapshots:
 
   process-nextick-args@2.0.1: {}
 
+  progress@2.0.3: {}
+
   protobufjs@7.6.4:
     dependencies:
       '@protobufjs/aspromise': 1.1.2
@@ -9165,6 +9254,12 @@ snapshots:
 
   stylis@4.4.0: {}
 
+  sumchecker@3.0.1:
+    dependencies:
+      debug: 4.4.3
+    transitivePeerDependencies:
+      - supports-color
+
   supports-color@7.2.0:
     dependencies:
       has-flag: 4.0.0
@@ -9286,6 +9381,8 @@ snapshots:
 
   undici-types@6.21.0: {}
 
+  undici-types@7.18.2: {}
+
   undici-types@7.24.6: {}
 
   undici@7.28.0: {}
diff --git a/tsconfig.build.json b/tsconfig.build.json
index 3a57169005..dd3004454f 100644
--- a/tsconfig.build.json
+++ b/tsconfig.build.json
@@ -59,6 +59,7 @@
     { "path": "./packages/ui/acp" },
     { "path": "./packages/examples/acp-demo" },
     { "path": "./packages/ui/app-boot" },
+    { "path": "./packages/ui/desktop" },
     { "path": "./packages/ui/jsonrpc" },
     { "path": "./packages/examples/jsonrpc-demo" },
     { "path": "./packages/ui/stdio" },
diff --git a/tsconfig.json b/tsconfig.json
index 6585a987d6..4fc7dbb0c3 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -70,6 +70,7 @@
     { "path": "./packages/ui/acp" },
     { "path": "./packages/examples/acp-demo" },
     { "path": "./packages/ui/app-boot" },
+    { "path": "./packages/ui/desktop" },
     { "path": "./packages/ui/jsonrpc" },
     { "path": "./packages/examples/jsonrpc-demo" },
     { "path": "./packages/ui/stdio" },