Replace setTimeout with a periodic chrome alarm for more reliable WebSocket reconnection in the background service worker

Author: robertpiosik

apps/browser/src/background/keep-alive.ts

@@ -1,23 +1,30 @@
 import browser from 'webextension-polyfill'
 import { check_and_recover_connection } from './websocket'
+const ALARM_NAME = 'keep-alive'
+const ALARM_PERIOD_MINUTES = 0.5 // fires every 30 seconds
+
 
 export const setup_keep_alive = () => {
   if (!browser.browserAction) {
-    const create_keep_alive_alarm = async () => {
-      try {
-        chrome.alarms.create('keep-alive', {
-          when: Date.now() + 1000 * 30
-        })
-      } catch (error) {
-        console.error('Error creating KeepAlive alarm:', error)
-      }
+    const ensure_alarm = () => {
+      chrome.alarms.get(ALARM_NAME, (alarm) => {
+        if (!alarm) {
+          chrome.alarms.create(ALARM_NAME, {
+            delayInMinutes: ALARM_PERIOD_MINUTES,
+            periodInMinutes: ALARM_PERIOD_MINUTES
+          })
+        }
+      })
     }
+    chrome.runtime.onStartup.addListener(ensure_alarm)
+    chrome.runtime.onInstalled.addListener(ensure_alarm)
+    ensure_alarm()
+
+    chrome.alarms.onAlarm.addListener((alarm) => {
+      if (alarm.name === ALARM_NAME) {
+        check_and_recover_connection()
+      }
 
-    chrome.runtime.onStartup.addListener(create_keep_alive_alarm)
-    chrome.runtime.onInstalled.addListener(create_keep_alive_alarm)
-    chrome.alarms.onAlarm.addListener(() => {
-      create_keep_alive_alarm()
-      check_and_recover_connection()
     })
   }
 }

apps/browser/src/background/websocket.ts

@@ -1,6 +1,5 @@
 import { WebSocketMessage } from '@shared/types/websocket-message'
 import { handle_messages } from './message-handler'
-import { CONFIG } from './config'
 import { DEFAULT_PORT, SECURITY_TOKENS } from '@shared/constants/websocket'
 import browser from 'webextension-polyfill'
 let websocket: WebSocket | null = null
@@ -23,12 +22,13 @@ export const check_and_recover_connection = () => {
       console.warn(
         'WebSocket connection is stale (no recent pings). Force reconnecting...'
       )
+      is_reconnecting = false
       websocket.close()
     }
-  } else if (
-    !is_reconnecting &&
-    websocket?.readyState !== WebSocket.CONNECTING
-  ) {
+  }
+
+  if (!is_reconnecting && websocket?.readyState !== WebSocket.OPEN &&
+      websocket?.readyState !== WebSocket.CONNECTING) {
     connect_websocket()
   }
 }
@@ -49,10 +49,8 @@ export const connect_websocket = async (): Promise<void> => {
     const is_healthy = await check_server_health()
     if (!is_healthy) {
       console.debug('Server health check failed, retrying in 5 seconds...')
-      setTimeout(() => {
-        is_reconnecting = false
-        connect_websocket()
-      }, CONFIG.RECONNECT_DELAY)
+      // Let the periodic alarm drive the next retry — setTimeout is unreliable in service workers
+      is_reconnecting = false
       return
     }
 
@@ -84,7 +82,7 @@ export const connect_websocket = async (): Promise<void> => {
       console.log('Disconnected from VS Code, attempting to reconnect...')
       websocket = null
       is_reconnecting = false
-      setTimeout(connect_websocket, CONFIG.RECONNECT_DELAY)
+      // Reconnect attempt will be driven by the next alarm tick
     }
 
     websocket.onerror = () => {
@@ -93,7 +91,6 @@ export const connect_websocket = async (): Promise<void> => {
     }
   } catch {
     is_reconnecting = false
-    setTimeout(connect_websocket, CONFIG.RECONNECT_DELAY)
   }
 }
 

apps/browser/src/manifest.json

@@ -4,7 +4,7 @@
   "name": "Autofill for Code Web Chat",
   "short_name": "CWC",
   "description": "Got tired with copy and paste? Enable prompt autofill!",
-  "version": "1.114.0",
+  "version": "1.115.0",
   "homepage_url": "https://github.com/robertpiosik/CodeWebChat",
   "icons": {
     "16": "icons/icon-16.png",