diff --git a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.i18n.yaml b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.i18n.yaml
index 6e3bbade75..34091877bf 100644
--- a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.i18n.yaml
+++ b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write
-2026-07-24-web-plan-mode.md: 42407198c09c34f2ddde559f5ddeae8d7736169e
-2026-07-24-web-plan-mode.zh.md: db865a26e91977670ed520aecf9d683a6bea5dab
+2026-07-24-web-plan-mode.md: 3b8a14a279dee478a291b19d5c0aed82f5a16c5c
+2026-07-24-web-plan-mode.zh.md: ca52918257c289fab966f1915348b08de45d86f1
diff --git a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.md b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.md
index 42407198c0..3b8a14a279 100644
--- a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.md
+++ b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.md
@@ -18,7 +18,7 @@ The policy is product-owned configuration at this composition boundary. It tells
 
 `ui-conversation` owns and renders the new additive controls slot to the left of the primary composer action. It provides no business payload; entries receive the standard session kit. Whole-composer replacements remain on the separate selector-routed `conversation.composer` chain, so a pending question replaces the InputBar and its controls without either feature importing the other.
 
-The control is absent when `planMode` is `null`. Otherwise, its selected value is `pending ?? active`, while pending presentation tests field presence rather than truthiness. It displays `计划 · 待生效` or `默认 · 待生效` until a logged commit replaces the snapshot. A selection disables only the selector while its own RPC is in flight. Generation does not disable it: selecting during a running turn neither calls cancel nor changes that turn, and cancelling generation does not clear the pending target.
+The control is absent when `planMode` is `null`. Otherwise, its selected value is `pending ?? active`, while pending presentation tests field presence rather than truthiness. It displays `计划 · 待生效` or `默认 · 待生效` until a logged commit replaces the snapshot. The transparent native select mirrors focus onto the visible chip and references a dynamic accessible description that distinguishes committed mode from the pending target. A selection disables only the selector while its own RPC is in flight. Generation does not disable it: selecting during a running turn neither calls cancel nor changes that turn, and cancelling generation does not clear the pending target.
 
 ## Interaction semantics
 
diff --git a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.zh.md b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.zh.md
index db865a26e9..ca52918257 100644
--- a/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.zh.md
+++ b/.agents/notes/implemented/feature/2026-07-24-web-plan-mode.zh.md
@@ -18,7 +18,7 @@ Web 宿主可以通过[可选会话 RPC 契约](../architecture/2026-07-24-web-p
 
 `ui-conversation` 拥有并渲染新增的可叠加控件槽，其位置在 composer 主操作左侧。该槽不提供业务载荷；各入口接收标准会话注入项。替换整个 composer 的功能仍走另一条由选择器路由的 `conversation.composer` 链，因此待处理的问题会替换 InputBar 及其控件，两个功能均无需导入对方。
 
-当 `planMode` 为 `null` 时，控件不会出现。否则，其选中值为 `pending ?? active`，而待生效状态的呈现依据是字段是否存在，而非字段真值。在日志提交替换快照前，控件会显示 `计划 · 待生效` 或 `默认 · 待生效`。选择操作只会在自身 RPC 执行期间禁用选择器。生成过程不会禁用该控件：在运行中的轮次里选择模式，既不会调用取消，也不会改变该轮次；取消生成也不会清除待生效目标。
+当 `planMode` 为 `null` 时，控件不会出现。否则，其选中值为 `pending ?? active`，而待生效状态的呈现依据是字段是否存在，而非字段真值。在日志提交替换快照前，控件会显示 `计划 · 待生效` 或 `默认 · 待生效`。透明的原生 select 会将焦点状态映射到可见的 chip，并引用一条动态无障碍描述，以区分已提交模式和待生效目标。选择操作只会在自身 RPC 执行期间禁用选择器。生成过程不会禁用该控件：在运行中的轮次里选择模式，既不会调用取消，也不会改变该轮次；取消生成也不会清除待生效目标。
 
 ## 交互语义
 
diff --git a/apps/web/tests/smoke-fixture.e2e.ts b/apps/web/tests/smoke-fixture.e2e.ts
index 2a847eea40..0c6776cf5e 100644
--- a/apps/web/tests/smoke-fixture.e2e.ts
+++ b/apps/web/tests/smoke-fixture.e2e.ts
@@ -252,9 +252,20 @@ describe('web boot chain success pass (keyless, ten real bundles, ?fixture)', ()
     const select = page.getByRole('combobox', { name: '协作模式' })
     await select.waitFor({ state: 'visible', timeout: 15_000 })
     await expect(page.getByTitle('当前为默认模式').isVisible()).resolves.toBe(true)
+    await select.focus()
+    expect(await select.evaluate((element) => {
+      const chip = element.parentElement?.firstElementChild
+      if (!(chip instanceof HTMLElement)) return null
+      const style = getComputedStyle(chip)
+      return { outlineStyle: style.outlineStyle, outlineWidth: style.outlineWidth }
+    })).toEqual({ outlineStyle: 'solid', outlineWidth: '2px' })
 
     await select.selectOption('plan')
     await page.getByTitle(/计划模式将在下一次模型请求时生效/).waitFor()
+    const descriptionId = await select.getAttribute('aria-describedby')
+    expect(descriptionId).not.toBeNull()
+    expect(await page.locator(`[id="${descriptionId}"]`).textContent())
+      .toBe('当前为默认模式；计划模式将在下一次模型请求时生效')
     const input = page.locator('textarea[placeholder]')
     await input.fill('commit plan mode')
     await page.getByRole('button', { name: '发送' }).click()
diff --git a/packages/client/ui-plan/README.md b/packages/client/ui-plan/README.md
index 17ad26ce6b..2a2a4478cd 100644
--- a/packages/client/ui-plan/README.md
+++ b/packages/client/ui-plan/README.md
@@ -2,7 +2,7 @@
 
 Web plan-mode feature with two lifecycle-coupled halves. The node entry mounts `@deepseek-ai/dsh-plan-mode` with the Web product policy; the browser entry contributes a session-scoped selector to `conversation.composer.controls`.
 
-The selector distinguishes unavailable capability (`planMode === null`), committed mode (`active`), and the target queued for the next model-request boundary (`pending`, including `pending: false`). Selecting a mode never cancels a running turn. It remains available while generation is running, disables only during its own RPC, and displays the host-confirmed pending target until a logged `plan/mode` event commits it.
+The selector distinguishes unavailable capability (`planMode === null`), committed mode (`active`), and the target queued for the next model-request boundary (`pending`, including `pending: false`). Selecting a mode never cancels a running turn. It remains available while generation is running, disables only during its own RPC, and displays the host-confirmed pending target until a logged `plan/mode` event commits it. The transparent native select mirrors keyboard focus onto the visible chip and carries a dynamic accessible description of the committed and pending modes.
 
 The model exits plan mode through the stable `exit_plan_mode` tool. Its plan review uses the composed Web question channel: approval schedules default mode for the next step, while rejection or custom feedback keeps plan mode active and returns the feedback to the model.
 
diff --git a/packages/client/ui-plan/src/client/PlanModeControl.module.css b/packages/client/ui-plan/src/client/PlanModeControl.module.css
index 8c679fe7c9..52bf367e3e 100644
--- a/packages/client/ui-plan/src/client/PlanModeControl.module.css
+++ b/packages/client/ui-plan/src/client/PlanModeControl.module.css
@@ -29,10 +29,27 @@
   background: var(--dsw-alias-interactive-bg-hover);
 }
 
+.root:focus-within .chip {
+  outline: 2px solid var(--dsw-alias-brand-primary);
+  outline-offset: 2px;
+}
+
 .chevron {
   color: var(--dsw-alias-label-caption);
 }
 
+.description {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
 .select {
   position: absolute;
   inset: 0;
diff --git a/packages/client/ui-plan/src/client/PlanModeControl.tsx b/packages/client/ui-plan/src/client/PlanModeControl.tsx
index a7f73e0590..d48b1f323e 100644
--- a/packages/client/ui-plan/src/client/PlanModeControl.tsx
+++ b/packages/client/ui-plan/src/client/PlanModeControl.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useRef, useState } from 'react'
+import { useEffect, useId, useRef, useState } from 'react'
 import type { PlanModeControlProps } from './index.ts'
 import css from './PlanModeControl.module.css'
 
@@ -13,6 +13,7 @@ export function PlanModeControl({ useSession, setPlanMode }: PlanModeControlProp
   const [switching, setSwitching] = useState(false)
   const [error, setError] = useState<string | null>(null)
   const aliveRef = useRef(true)
+  const descriptionId = useId()
 
   useEffect(() => {
     aliveRef.current = true
@@ -57,9 +58,11 @@ export function PlanModeControl({ useSession, setPlanMode }: PlanModeControlProp
             <path d="M3 4.5L6 7.5L9 4.5" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" fill="none" />
           </svg>
         </span>
+        <span id={descriptionId} className={css.description}>{title}</span>
         <select
           className={css.select}
           aria-label="协作模式"
+          aria-describedby={descriptionId}
           value={value}
           disabled={switching}
           onChange={(event) => { select(event.target.value === 'plan') }}
diff --git a/packages/client/ui-plan/tests/plan-mode-control.spec.tsx b/packages/client/ui-plan/tests/plan-mode-control.spec.tsx
index f344beeb1f..36baf559d7 100644
--- a/packages/client/ui-plan/tests/plan-mode-control.spec.tsx
+++ b/packages/client/ui-plan/tests/plan-mode-control.spec.tsx
@@ -40,17 +40,26 @@ describe('PlanModeControl', () => {
     cleanup()
     setup({ active: false })
     expect(screen.getByTitle('当前为默认模式')).toBeTruthy()
-    expect((screen.getByRole('combobox', { name: '协作模式' }) as HTMLSelectElement).value).toBe('default')
+    const select = screen.getByRole('combobox', { name: '协作模式' }) as HTMLSelectElement
+    expect(select.value).toBe('default')
+    expect(document.getElementById(select.getAttribute('aria-describedby') ?? '')?.textContent)
+      .toBe('当前为默认模式')
   })
 
   it('treats pending field presence as the target, including pending false', () => {
     setup({ active: false, pending: true })
     expect(screen.getByText('计划 · 待生效')).toBeTruthy()
     expect(screen.getByTitle(/当前为默认模式/)).toBeTruthy()
+    const planSelect = screen.getByRole('combobox')
+    expect(document.getElementById(planSelect.getAttribute('aria-describedby') ?? '')?.textContent)
+      .toBe('当前为默认模式；计划模式将在下一次模型请求时生效')
     cleanup()
     setup({ active: true, pending: false })
     expect(screen.getByText('默认 · 待生效')).toBeTruthy()
-    expect((screen.getByRole('combobox') as HTMLSelectElement).value).toBe('default')
+    const defaultSelect = screen.getByRole('combobox') as HTMLSelectElement
+    expect(defaultSelect.value).toBe('default')
+    expect(document.getElementById(defaultSelect.getAttribute('aria-describedby') ?? '')?.textContent)
+      .toBe('当前为计划模式；默认模式将在下一次模型请求时生效')
   })
 
   it('switches from the effective target and remains available while a turn runs', async () => {