fix Runtime.enable race condition with event-based synchronization

Replace arbitrary sleep(200ms) with proper wait for Runtime.executionContextCreated
event in the relay server. This ensures pages are fully ready before Runtime.enable
returns to Playwright, fixing intermittent 'page not found' errors.

extension/src/background.ts

@@ -230,9 +230,15 @@ async function handleCommand(msg: ExtensionCommandMessage): Promise<any> {
       if (!debuggee) {
         throw new Error(`No debuggee found for Runtime.enable (sessionId: ${msg.params.sessionId})`)
       }
+      // When multiple Playwright clients connect to the same tab, each calls Runtime.enable.
+      // If Runtime is already enabled, the enable call succeeds but Chrome doesn't re-send
+      // Runtime.executionContextCreated events - those were already sent to the first client.
+      // By disabling first, we force Chrome to re-send all execution context events when we
+      // re-enable, ensuring the new client receives them. The relay server waits for the
+      // executionContextCreated events before returning. See cdp-timing.md for details.
       try {
         await chrome.debugger.sendCommand(debuggee, 'Runtime.disable')
-        await sleep(400)
+        await sleep(50)
       } catch (e) {
         logger.debug('Error disabling Runtime (ignoring):', e)
       }
@@ -360,8 +366,6 @@ async function attachTab(tabId: number): Promise<Protocol.Target.TargetInfo> {
 
   await chrome.debugger.sendCommand(debuggee, 'Page.enable')
 
-  await sleep(400)
-
   const result = (await chrome.debugger.sendCommand(
     debuggee,
     'Target.getTargetInfo',
@@ -507,15 +511,7 @@ function handleConnectionClose(reason: string, code: number): void {
     return
   }
 
-  store.setState((state) => {
-    const newTabs = new Map(state.tabs)
-    for (const [tabId, tab] of newTabs) {
-      if (tab.state === 'connected') {
-        newTabs.set(tabId, { ...tab, state: 'connecting' })
-      }
-    }
-    return { tabs: newTabs, connectionState: 'disconnected', errorText: undefined }
-  })
+  store.setState({ connectionState: 'disconnected', errorText: undefined })
 
   if (tabs.size > 0) {
     logger.debug('Tabs still connected, triggering reconnection')