Stop caching index.html and speed up socket reconnect

Phones offer no easy hard-refresh, so a cached index.html kept serving an old
bundle after a deploy (the live feed showed "reconnecting"). index.html and the
SPA catch-all now send Cache-Control: no-store, while hashed /assets stay
immutable. Also retry the first socket reconnect after 1s (was 2s) and surface
the close code in the header so a failure is actionable on a phone.

frontend/nginx.conf

@@ -4,7 +4,22 @@ server {
     root /usr/share/nginx/html;
     index index.html;
 
+    # Hashed Vite assets are immutable; cache them hard.
+    location /assets/ {
+        add_header Cache-Control "public, max-age=31536000, immutable";
+        try_files $uri =404;
+    }
+
+    # The HTML entry point must never be cached, or a phone (which offers no
+    # easy hard-refresh) keeps loading an old bundle after a deploy. The
+    # catch-all serves index.html for client-side routes, so it gets the same
+    # no-store header.
+    location = /index.html {
+        add_header Cache-Control "no-store";
+    }
+
     location / {
+        add_header Cache-Control "no-store";
         try_files $uri $uri/ /index.html;
     }
 

frontend/src/App.vue

@@ -36,6 +36,7 @@ const events = ref([])
 const equityPoints = ref([])
 const busy = ref(false)
 const connected = ref(false)
+const socketError = ref('')
 
 let socket
 let pollTimer
@@ -132,8 +133,15 @@ onMounted(async () => {
   ])
   socket = api.openSocket({
     onMessage: handleMessage,
-    onOpen: () => (connected.value = true),
+    onOpen: () => {
+      connected.value = true
+      socketError.value = ''
+    },
     onClose: () => (connected.value = false),
+    onError: (code) => {
+      if (code === 1008) socketError.value = 'rejected by the server (token/auth)'
+      else socketError.value = `socket closed (code ${code})`
+    },
   })
   pollTimer = setInterval(refreshAll, 5000)
 })
@@ -161,6 +169,7 @@ onUnmounted(() => {
             :class="connected ? 'bg-emerald-400' : 'bg-slate-500'"
           ></span>
           {{ connected ? 'live' : 'reconnecting' }}
+          <span v-if="!connected && socketError" class="text-amber-300">· {{ socketError }}</span>
         </span>
       </div>
       <div class="text-xs text-slate-400">

frontend/src/api.js

@@ -26,7 +26,7 @@ export const getPresets = () => http.get('/presets').then((r) => r.data)
 export const createPreset = (payload) => http.post('/presets', payload).then((r) => r.data)
 export const deletePreset = (id) => http.delete(`/presets/${id}`).then((r) => r.data)
 
-export function openSocket({ onMessage, onOpen, onClose }) {
+export function openSocket({ onMessage, onOpen, onClose, onError }) {
   const proto = window.location.protocol === 'https:' ? 'wss' : 'ws'
   const url = `${proto}://${window.location.host}/api/ws`
   let socket
@@ -36,9 +36,9 @@ export function openSocket({ onMessage, onOpen, onClose }) {
 
   const schedule = () => {
     if (closed) return
-    // Back off from 2s up to 30s so a persistently failing socket (e.g. auth)
-    // does not hammer the server, while a brief blip still reconnects fast.
-    const delay = Math.min(2000 * 2 ** attempt, 30000)
+    // Retry at 1s, then back off up to 30s so a persistently failing socket
+    // does not hammer the server while a brief blip recovers immediately.
+    const delay = Math.min(1000 * 2 ** attempt, 30000)
     attempt += 1
     retryTimer = setTimeout(connect, delay)
   }
@@ -51,8 +51,11 @@ export function openSocket({ onMessage, onOpen, onClose }) {
       onOpen?.()
     }
     socket.onmessage = (event) => onMessage?.(JSON.parse(event.data))
-    socket.onclose = () => {
+    socket.onclose = (event) => {
       onClose?.()
+      // 1008 = policy violation (token rejected); 1006 = abnormal close, which
+      // is what an auth/proxy rejection looks like to the browser.
+      onError?.(event.code, event.reason)
       schedule()
     }
     socket.onerror = () => socket.close()