fix: allow closing browser tabs during active requests

Allow users to close leased browser tabs without cancelling the AI request or revoking its other tools. Closed-page operations report a recoverable error; explicit navigation creates a dedicated replacement tab for direct-model and MCP calls.

Add regression coverage and real Electron lifecycle checks, and update browser behavior documentation.

Release note: 浏览器标签页被 AI 请求占用时也可关闭，其他任务继续运行；再次导航会打开独立新页。

src/main/browser/browser-model-tools.test.ts

@@ -245,4 +245,48 @@ describe('BrowserModelTools', () => {
       tools.callTool('browser_snapshot', {}, controller.signal)
     ).rejects.toHaveProperty('name', 'AbortError')
   })
+
+  it('validates explicit recovery navigation before creating a dedicated replacement', async () => {
+    const service = createService()
+    service.acquireTabUsage = vi.fn(() => { throw new Error('closed') })
+    service.createTab = vi.fn()
+    const tools = new BrowserModelTools({
+      service, conversationId: 'conversation', browserTabId, recoverClosedTab: true
+    })
+    for (const args of [{}, { url: 'file:///private' }, { url: 'https://example.com', extra: true }]) {
+      await expect(tools.callTool('browser_navigate', args, signal)).rejects.toThrow()
+    }
+    await expect(tools.callTool('browser_snapshot', {}, signal)).rejects.toHaveProperty('name', 'BrowserTabClosedError')
+    await expect(tools.callTool('browser_navigate', { url: 'https://example.com' }, AbortSignal.abort()))
+      .rejects.toHaveProperty('name', 'AbortError')
+    expect(service.createTab).not.toHaveBeenCalled()
+    expect(service.navigate).not.toHaveBeenCalled()
+  })
+
+  it('preserves request cancellation and releases the per-call lease', async () => {
+    const service = createService()
+    const leaseController = new AbortController()
+    const release = vi.fn()
+    service.acquireTabUsage = vi.fn(() => ({
+      conversationId: 'conversation', tabId: browserTabId, owner: 'request',
+      signal: leaseController.signal, release
+    }))
+    service.createTab = vi.fn()
+    vi.mocked(service.snapshot).mockImplementation(async (_conversationId, signal) =>
+      new Promise<never>((_resolve, reject) => {
+        signal.addEventListener('abort', () => reject(signal.reason), { once: true })
+      })
+    )
+    const tools = new BrowserModelTools({
+      service, conversationId: 'conversation', browserTabId, recoverClosedTab: true
+    })
+    const controller = new AbortController()
+    const reason = new Error('cancel request')
+    const pending = tools.callTool('browser_snapshot', {}, controller.signal)
+    const cancelled = expect(pending).rejects.toBe(reason)
+    controller.abort(reason)
+    await cancelled
+    expect(release).toHaveBeenCalledOnce()
+    expect(service.createTab).not.toHaveBeenCalled()
+  })
 })

src/main/browser/browser-model-tools.ts

@@ -7,7 +7,7 @@ import type {
 } from '../agent/model-tool-provider'
 import type { RuntimeApprovalRequest } from '../agent/runtime'
 import { canonicalizeBrowserUrl } from './browser-url-policy'
-import type { BrowserService } from './browser-service'
+import type { BrowserService, BrowserTabUsageLease } from './browser-service'
 import {
   MAX_BROWSER_INPUT_LENGTH as MAX_INPUT_LENGTH,
   MAX_BROWSER_SELECT_LENGTH as MAX_SELECT_LENGTH
@@ -191,12 +191,21 @@ export type BrowserToolService = Pick<
   | 'back'
   | 'screenshot'
   | 'releaseConversation'
->
+> & Partial<Pick<BrowserService, 'acquireTabUsage' | 'createTab'>>
 
 export type BrowserModelToolsOptions = {
   service: BrowserToolService
   conversationId: string
   browserTabId: BrowserTabId
+  // The scoped gateway manages its own binding and lease lifecycle.
+  recoverClosedTab?: boolean
+}
+
+export class BrowserTabClosedError extends Error {
+  constructor(options?: ErrorOptions) {
+    super('浏览器标签页已关闭，请调用 browser_navigate 打开新标签页。', options)
+    this.name = 'BrowserTabClosedError'
+  }
 }
 
 function createTextResult(value: unknown): ModelToolResult {
@@ -220,12 +229,15 @@ function navigationLabel(url: URL): string {
 export class BrowserModelTools {
   private readonly service: BrowserToolService
   private readonly conversationId: string
-  private readonly browserTabId: BrowserTabId
+  private browserTabId: BrowserTabId
+  private readonly recoveryOwner = randomUUID()
+  private readonly recoverClosedTab: boolean
 
   constructor(options: BrowserModelToolsOptions) {
     this.service = options.service
     this.conversationId = options.conversationId
     this.browserTabId = options.browserTabId
+    this.recoverClosedTab = options.recoverClosedTab === true
     if (!this.conversationId || this.conversationId.length > 500) {
       throw new Error('浏览器对话标识无效')
     }
@@ -321,6 +333,53 @@ export class BrowserModelTools {
     if (!this.ownsTool(name)) {
       throw new Error(`未知浏览器工具：${name}`)
     }
+    if (!this.recoverClosedTab || !this.service.acquireTabUsage || !this.service.createTab) {
+      return this.callBoundTool(name, argumentsValue, signal, this.browserTabId)
+    }
+    let lease: BrowserTabUsageLease
+    try {
+      lease = this.service.acquireTabUsage(
+        this.conversationId, this.browserTabId, this.recoveryOwner
+      )
+    } catch (error) {
+      if (name !== 'browser_navigate') {
+        throw new BrowserTabClosedError({ cause: error })
+      }
+      const input = browserNavigateInputSchema.parse(argumentsValue)
+      canonicalizeBrowserUrl(input.url)
+      const tab = await this.service.createTab(
+        this.conversationId, undefined, signal,
+        `browser-recovery:${this.recoveryOwner}:${this.browserTabId}`
+      )
+      signal.throwIfAborted()
+      lease = this.service.acquireTabUsage(
+        this.conversationId, tab.tabId, this.recoveryOwner
+      )
+      this.browserTabId = tab.tabId
+    }
+    const browserSignal = AbortSignal.any([signal, lease.signal])
+    try {
+      const result = await this.callBoundTool(name, argumentsValue, browserSignal, lease.tabId)
+      browserSignal.throwIfAborted()
+      return result
+    } catch (error) {
+      signal.throwIfAborted()
+      if (lease.signal.aborted) {
+        throw new BrowserTabClosedError({ cause: error })
+      }
+      throw error
+    } finally {
+      lease.release()
+    }
+  }
+
+  private async callBoundTool(
+    name: BrowserToolName,
+    argumentsValue: Record<string, unknown>,
+    signal: AbortSignal,
+    browserTabId: BrowserTabId
+  ): Promise<ModelToolResult> {
+    signal.throwIfAborted()
     if (name === 'browser_navigate') {
       const input = browserNavigateInputSchema.parse(argumentsValue)
       return createTextResult(
@@ -328,7 +387,7 @@ export class BrowserModelTools {
           this.conversationId,
           input.url,
           signal,
-          this.browserTabId
+          browserTabId
         )
       )
     }
@@ -338,7 +397,7 @@ export class BrowserModelTools {
         await this.service.snapshot(
           this.conversationId,
           signal,
-          this.browserTabId
+          browserTabId
         )
       )
     }
@@ -348,7 +407,7 @@ export class BrowserModelTools {
         this.conversationId,
         input.ref,
         signal,
-        this.browserTabId
+        browserTabId
       )
       return createTextResult({ clicked: input.ref })
     }
@@ -359,7 +418,7 @@ export class BrowserModelTools {
         input.ref,
         input.text,
         signal,
-        this.browserTabId
+        browserTabId
       )
       return createTextResult({
         typed: input.ref,
@@ -374,7 +433,7 @@ export class BrowserModelTools {
         input.ref,
         input.value,
         signal,
-        this.browserTabId
+        browserTabId
       )
       return createTextResult({ selected: input.ref, value: '[已隐藏]' })
     }
@@ -384,7 +443,7 @@ export class BrowserModelTools {
         await this.service.back(
           this.conversationId,
           signal,
-          this.browserTabId
+          browserTabId
         )
       )
     }
@@ -392,7 +451,7 @@ export class BrowserModelTools {
     const screenshot = await this.service.screenshot(
       this.conversationId,
       signal,
-      this.browserTabId
+      browserTabId
     )
     return {
       parts: [

src/main/browser/browser-service.test.ts

@@ -227,7 +227,8 @@ describe('BrowserService', () => {
     expect(restored.tabId).toBe(first.tabId)
     expect(harness.service.getTabCount()).toBe(1)
     first.release()
-    await expect(harness.service.closeTab('conversation', first.tabId, 21)).rejects.toThrow('正在被活动请求使用')
+    await harness.service.closeTab('conversation', first.tabId, 21)
+    expect(second.signal.aborted).toBe(true)
     second.release()
     await harness.service.closeTab('conversation', first.tabId, 21)
     await harness.service.closeTab('conversation', first.tabId, 21)
@@ -557,7 +558,7 @@ describe('BrowserService', () => {
     await harness.service.dispose()
   })
 
-  it('blocks closing a leased tab until every request releases it', async () => {
+  it('closes a leased tab and ends its leases without closing sibling tabs', async () => {
     const harness = createHarness()
     const signal = new AbortController().signal
     const primary = await harness.service.createTab('conversation', 11, signal)
@@ -577,15 +578,14 @@ describe('BrowserService', () => {
 
     await expect(
       harness.service.closeTab('conversation', primary.tabId, 11)
-    ).rejects.toThrow('浏览器标签页正在被活动请求使用，无法关闭')
-    await expect(
-      harness.service.closeTab('conversation', sibling.tabId, 11)
     ).resolves.toBeUndefined()
+    expect(first.signal.aborted).toBe(true)
+    expect(second.signal.aborted).toBe(true)
+    expect(harness.service.listTabs('conversation', 11).map((tab) => tab.tabId)).toEqual([sibling.tabId])
+    expect(harness.slots[0]?.session.dispose).toHaveBeenCalledOnce()
+    expect(harness.slots[1]?.session.dispose).not.toHaveBeenCalled()
     first.release()
     first.release()
-    await expect(
-      harness.service.closeTab('conversation', primary.tabId, 11)
-    ).rejects.toThrow('浏览器标签页正在被活动请求使用，无法关闭')
     second.release()
     await expect(
       harness.service.closeTab('conversation', primary.tabId, 11)

src/main/browser/browser-service.ts

@@ -31,9 +31,6 @@ export class BrowserNavigationStoppedError extends Error {
   }
 }
 
-export const BROWSER_TAB_IN_USE_ERROR =
-  '浏览器标签页正在被活动请求使用，无法关闭'
-
 export type BrowserTabUsageLease = {
   readonly conversationId: string
   readonly tabId: BrowserTabId
@@ -908,12 +905,14 @@ export class BrowserService {
         [...this.creations.entries()].some(([id, slot]) => slot.tabId === tabId && id !== conversationId) ||
         [...this.requestTabs.values()].some((slot) => slot.tabId === tabId && slot.conversationId !== conversationId)
       ) throw new Error('浏览器标签页不存在或不属于当前对话')
-      if (reservation?.tabId === tabId && reservation.usageLeases.size > 0) {
-        throw new Error(BROWSER_TAB_IN_USE_ERROR)
+      if (reservation?.tabId === tabId) {
+        this.releaseRequestTab(conversationId)
+      }
+      if (creation?.tabId === tabId) {
+        creation.controller.abort(new Error('浏览器会话已关闭'))
       }
       return
     }
-    if (tab.usageLeases.size > 0) throw new Error(BROWSER_TAB_IN_USE_ERROR)
     await this.releaseTab(conversation!, tab)
   }