diff --git a/public/sw.js b/public/sw.js
index 8b13789..62301fc 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -1 +1,19 @@
+const log = (...a) => console.log('[SW]', ...a)
 
+self.addEventListener('install', e => {
+  log('install')
+  self.skipWaiting()
+})
+
+self.addEventListener('activate', e => {
+  log('activate')
+  e.waitUntil(self.clients.claim())
+})
+
+self.addEventListener('fetch', e => {
+  if (e.request.mode === 'navigate') log('navigate', e.request.url)
+})
+
+self.addEventListener('message', e => {
+  log('message', e.data)
+})