fix: route Target.detachFromTarget on root CDP session (#40)

When Playwright sends Target.detachFromTarget via the root browser session
(no top-level sessionId), the extension couldn't find the target tab because
it only checked msg.params.sessionId for routing. This caused 'No tab found'
errors that cascaded into disconnects and instability.

- Add getTabForCommand() helper with params.sessionId fallback so any command
  referencing a session in its params can be routed when the top-level
  sessionId is absent
- No-op Target.detachFromTarget for stale/unknown sessions instead of throwing
- Always re-apply tab group color on every sync to prevent Chrome resetting
  it to white
- Replace silent .catch() with error log in aria-snapshot OOPIF detach
- Add regression test using raw WebSocket to verify routing without sessionId

Extension bumped to 0.0.74.

extension/CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.0.74
+
+### Bug Fixes
+
+- **Fix Target.detachFromTarget routing on root CDP session**: Commands sent without a top-level sessionId (e.g. from Playwright's root browser session) now resolve the target tab via `params.sessionId` fallback. Previously the extension threw "No tab found" which caused cascading disconnects and instability. (#40)
+- **No-op stale Target.detachFromTarget**: Unknown or already-cleaned-up sessions return `{}` instead of throwing, preventing error cascading during rapid connect/disconnect cycles.
+- **Always re-apply tab group color**: Tab group title and color are now re-applied on every sync to prevent Chrome from resetting them to white/unlabeled.
+
 ## 0.0.73
 
 ### Bug Fixes

extension/manifest.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "Playwriter",
-  "version": "0.0.73",
+  "version": "0.0.74",
   "description": "Automate your Browser using Cursor, Claude, VS Code. More capable and context efficient than Playwright MCP.",
   "permissions": [
     "alarms",

extension/src/background.ts

@@ -102,6 +102,9 @@ async function getExtensionIdentity(): Promise<ExtensionIdentity> {
   return identityPromise
 }
 
+const TAB_GROUP_COLOR: chrome.tabGroups.ColorEnum = 'green'
+const TAB_GROUP_TITLE = 'playwriter'
+
 let childSessions: Map<string, { tabId: number; targetId?: string }> = new Map()
 let nextSessionId = 1
 let tabGroupQueue: Promise<void> = Promise.resolve()
@@ -722,7 +725,7 @@ async function syncTabGroup(): Promise<void> {
       .map(([tabId]) => tabId)
 
     // Always query by title - no cached ID that can go stale
-    const existingGroups = await chrome.tabGroups.query({ title: 'playwriter' })
+    const existingGroups = await chrome.tabGroups.query({ title: TAB_GROUP_TITLE })
 
     // If no connected tabs, clear any existing playwriter groups
     if (connectedTabIds.length === 0) {
@@ -771,12 +774,17 @@ async function syncTabGroup(): Promise<void> {
     if (tabsToAdd.length > 0) {
       if (groupId === undefined) {
         const newGroupId = await chrome.tabs.group({ tabIds: tabsToAdd })
-        await chrome.tabGroups.update(newGroupId, { title: 'playwriter', color: 'green' })
+        await chrome.tabGroups.update(newGroupId, { title: TAB_GROUP_TITLE, color: TAB_GROUP_COLOR })
         logger.debug('Created tab group:', newGroupId, 'with tabs:', tabsToAdd)
       } else {
         await chrome.tabs.group({ tabIds: tabsToAdd, groupId })
+        await chrome.tabGroups.update(groupId, { title: TAB_GROUP_TITLE, color: TAB_GROUP_COLOR })
         logger.debug('Added tabs to existing group:', tabsToAdd)
       }
+    } else if (groupId !== undefined) {
+      // No tabs to add, but ensure the existing group keeps the right color/title.
+      // Chrome can reset these on group collapse/expand or tab moves.
+      await chrome.tabGroups.update(groupId, { title: TAB_GROUP_TITLE, color: TAB_GROUP_COLOR })
     }
   } catch (error: any) {
     logger.debug('Failed to sync tab group:', error.message)
@@ -820,37 +828,61 @@ function emitChildDetachesForTab(tabId: number): void {
   })
 }
 
+// Resolve which tab a CDP command targets by checking sessionId sources in priority order:
+// 1. Top-level sessionId (the CDP session the command was sent on)
+// 2. params.sessionId (e.g. Target.detachFromTarget on the root session, see #40)
+// 3. params.targetId (e.g. Target.closeTarget)
+function getTabForCommand(msg: ExtensionCommandMessage): { tabId: number; tab: TabInfo } | undefined {
+  const sessionId = msg.params.sessionId
+  if (sessionId) {
+    const found = getTabBySessionId(sessionId)
+    if (found) {
+      return found
+    }
+    const child = childSessions.get(sessionId)
+    if (child) {
+      const tab = store.getState().tabs.get(child.tabId)
+      if (tab) {
+        return { tabId: child.tabId, tab }
+      }
+    }
+  }
+
+  const paramsSessionId =
+    msg.params.params && 'sessionId' in msg.params.params && typeof msg.params.params.sessionId === 'string'
+      ? msg.params.params.sessionId
+      : undefined
+  if (paramsSessionId) {
+    const found = getTabBySessionId(paramsSessionId)
+    if (found) {
+      return found
+    }
+    const child = childSessions.get(paramsSessionId)
+    if (child) {
+      const tab = store.getState().tabs.get(child.tabId)
+      if (tab) {
+        return { tabId: child.tabId, tab }
+      }
+    }
+  }
+
+  const targetId =
+    msg.params.params && 'targetId' in msg.params.params && typeof msg.params.params.targetId === 'string'
+      ? msg.params.params.targetId
+      : undefined
+  if (targetId) {
+    return getTabByTargetId(targetId)
+  }
+
+  return undefined
+}
+
 async function handleCommand(msg: ExtensionCommandMessage): Promise<any> {
   if (msg.method !== 'forwardCDPCommand') return
 
-  let targetTabId: number | undefined
-  let targetTab: TabInfo | undefined
-
-  if (msg.params.sessionId) {
-    const found = getTabBySessionId(msg.params.sessionId)
-    if (found) {
-      targetTabId = found.tabId
-      targetTab = found.tab
-    }
-  }
-
-  if (!targetTab && msg.params.sessionId) {
-    const childSession = childSessions.get(msg.params.sessionId)
-    if (childSession) {
-      targetTabId = childSession.tabId
-      targetTab = store.getState().tabs.get(childSession.tabId)
-      logger.debug('Found parent tab for child session:', msg.params.sessionId, 'tabId:', childSession.tabId)
-    }
-  }
-
-  if (!targetTab && msg.params.params && 'targetId' in msg.params.params && msg.params.params.targetId) {
-    const found = getTabByTargetId(msg.params.params.targetId as string)
-    if (found) {
-      targetTabId = found.tabId
-      targetTab = found.tab
-      logger.debug('Found tab for targetId:', msg.params.params.targetId, 'tabId:', targetTabId)
-    }
-  }
+  const resolved = getTabForCommand(msg)
+  let targetTabId = resolved?.tabId
+  let targetTab = resolved?.tab
 
   const debuggee = targetTabId ? { tabId: targetTabId } : undefined
 
@@ -936,6 +968,11 @@ async function handleCommand(msg: ExtensionCommandMessage): Promise<any> {
   }
 
   if (!debuggee || !targetTab) {
+    // Target.detachFromTarget is best-effort — no-op if the session is already gone (#40).
+    if (msg.params.method === 'Target.detachFromTarget') {
+      return {}
+    }
+
     throw new Error(
       `No tab found for method ${msg.params.method} sessionId: ${msg.params.sessionId} params: ${JSON.stringify(msg.params.params || null)}`,
     )
@@ -1601,7 +1638,7 @@ chrome.tabs.onUpdated.addListener((tabId, changeInfo, tab) => {
     tabGroupQueue = tabGroupQueue
       .then(async () => {
         // Query for playwriter group by title - no stale cached ID
-        const existingGroups = await chrome.tabGroups.query({ title: 'playwriter' })
+        const existingGroups = await chrome.tabGroups.query({ title: TAB_GROUP_TITLE })
         const groupId = existingGroups[0]?.id
         if (groupId === undefined) {
           return

playwriter/src/aria-snapshot.ts

@@ -1260,7 +1260,9 @@ export async function getAriaSnapshot({
       }, scopeAttr)
     }
     if (oopifSessionId) {
-      await session.send('Target.detachFromTarget', { sessionId: oopifSessionId }).catch(() => {})
+      await session.send('Target.detachFromTarget', { sessionId: oopifSessionId }).catch((e) => {
+        console.error('[aria-snapshot] Failed to detach OOPIF session:', oopifSessionId, e)
+      })
     }
     if (!cdp) {
       await session.detach()

playwriter/src/relay-navigation.test.ts

@@ -1,5 +1,6 @@
 import { describe, it, expect, beforeAll, afterAll } from 'vitest'
 import { chromium, type Page } from '@xmorse/playwright-core'
+import WebSocket from 'ws'
 import { getCdpUrl } from './utils.js'
 import {
   setupTestContext,
@@ -625,4 +626,135 @@ describe('Relay Navigation Tests', () => {
     fs.unlinkSync(outputPath)
     fs.unlinkSync(demoPath)
   }, 60000)
+
+  // Regression test for https://github.com/remorses/playwriter/issues/40
+  // When Playwright sends Target.detachFromTarget on the root CDP session (no top-level
+  // sessionId), the extension must still route the command by looking at params.sessionId.
+  // Previously the extension threw "No tab found for method Target.detachFromTarget"
+  // because it only checked the top-level sessionId for routing, which is absent on root
+  // session commands. This caused cascading disconnects and instability.
+  it('should route Target.detachFromTarget without top-level sessionId (issue #40)', async () => {
+    const browserContext = getBrowserContext()
+    const serviceWorker = await getExtensionServiceWorker(browserContext)
+
+    const server = await createSimpleServer({
+      routes: { '/': '<!doctype html><html><body>detach test</body></html>' },
+    })
+
+    const page = await browserContext.newPage()
+    try {
+      await page.goto(server.baseUrl, { waitUntil: 'domcontentloaded' })
+      await page.bringToFront()
+
+      await withTimeout({
+        promise: serviceWorker.evaluate(async () => {
+          await globalThis.toggleExtensionForActiveTab()
+        }),
+        timeoutMs: 5000,
+        errorMessage: 'Timed out toggling extension for detach test',
+      })
+      await new Promise((r) => {
+        setTimeout(r, 400)
+      })
+
+      // Connect a raw WebSocket to the relay — this lets us send CDP messages
+      // exactly as they appear on the wire, without Playwright adding sessionId.
+      const ws = new WebSocket(`ws://localhost:${TEST_PORT}/cdp/test-detach-raw`)
+      await new Promise<void>((resolve, reject) => {
+        ws.on('open', () => {
+          resolve()
+        })
+        ws.on('error', reject)
+      })
+
+      let nextId = 1
+      const sendCdp = <T = unknown>(msg: Record<string, unknown>): Promise<T> => {
+        return new Promise((resolve, reject) => {
+          const id = nextId++
+          const timeout = setTimeout(() => {
+            ws.off('message', handler)
+            reject(new Error(`CDP response timeout for id ${id}`))
+          }, 5000)
+
+          const handler = (data: WebSocket.RawData) => {
+            const parsed = JSON.parse(data.toString())
+            if (parsed.id === id) {
+              ws.off('message', handler)
+              clearTimeout(timeout)
+              resolve(parsed as T)
+            }
+          }
+          ws.on('message', handler)
+          ws.send(JSON.stringify({ id, ...msg }))
+        })
+      }
+
+      // Collect async events from the relay
+      const events: Array<{ method: string; params: Record<string, unknown>; sessionId?: string }> = []
+      ws.on('message', (data) => {
+        const msg = JSON.parse(data.toString())
+        if (!msg.id && msg.method) {
+          events.push(msg)
+        }
+      })
+
+      // Trigger Target.setAutoAttach so the relay sends Target.attachedToTarget for
+      // all connected tabs. This gives us the page's pw-tab-* sessionId.
+      await sendCdp({
+        method: 'Target.setAutoAttach',
+        params: { autoAttach: true, waitForDebuggerOnStart: false, flatten: true },
+      })
+
+      // Wait for events to arrive
+      await new Promise((r) => {
+        setTimeout(r, 500)
+      })
+
+      // Filter for the specific page target by URL to avoid grabbing wrong sessions
+      // (welcome tab, extension pages, etc.)
+      type AttachParams = { sessionId?: string; targetInfo?: { type?: string; url?: string } }
+      const attachEvent = events.find((e) => {
+        if (e.method !== 'Target.attachedToTarget') {
+          return false
+        }
+        const p = e.params as AttachParams
+        return p.targetInfo?.type === 'page' && p.targetInfo?.url?.startsWith(server.baseUrl)
+      })
+      expect(attachEvent).toBeDefined()
+      const pageSessionId = (attachEvent!.params as AttachParams).sessionId
+      expect(pageSessionId).toBeTruthy()
+
+      // Verify the session is usable before detach — send a command that requires routing.
+      const evalBefore = await sendCdp<{ id: number; error?: { message: string }; result?: unknown }>({
+        method: 'Runtime.evaluate',
+        sessionId: pageSessionId,
+        params: { expression: '1 + 1', returnByValue: true },
+      })
+      expect(evalBefore.error).toBeUndefined()
+      expect((evalBefore.result as { result?: { value?: number } })?.result?.value).toBe(2)
+
+      // NOW: send Target.detachFromTarget WITHOUT a top-level sessionId.
+      // This is the exact wire format Playwright uses when sending on the root session
+      // (e.g. from CRSession.detach() where _parentSession is the root browser session).
+      // The extension must route this by looking at params.sessionId.
+      const detachResult = await sendCdp<{ id: number; error?: { message: string }; result?: unknown }>({
+        method: 'Target.detachFromTarget',
+        // Intentionally NO sessionId field — this is the root session
+        params: { sessionId: pageSessionId },
+      })
+
+      // Must not fail with extension routing error — the command must reach Chrome.
+      // Chrome returns "No session with given id" because pw-tab-* is a virtual session
+      // managed by the relay, not a real Chrome CDP session. This is expected — the key
+      // proof is that the extension routed the command to Chrome instead of throwing
+      // "No tab found" at the routing layer.
+      expect(detachResult.error?.message).not.toContain('No tab found')
+      expect(detachResult.error?.message).toContain('No session with given id')
+
+      ws.close()
+    } finally {
+      await page.close()
+      await server.close()
+    }
+  }, 30000)
 })