diff --git a/static/app.js b/static/app.js
index 0fef892..07b72cc 100644
--- a/static/app.js
+++ b/static/app.js
@@ -1,4 +1,6 @@
 // app.js — ani-web frontend: search -> detail -> play, vanilla JS + hls.js
+const JSV = 10;  // bump with every app.js change; play-probe reports it so a
+                 // stale-cache phone is detectable server-side
 // BASE = this page's directory, so the app works at / or behind a
 // prefixing reverse proxy (e.g. https://host/ani/)
 const BASE = (() => {
@@ -73,7 +75,7 @@ function showStreamError(msg, retry) {
   // + report the client's capabilities so a failing browser is diagnosable
   // from server.log instead of by guesswork
   try {
-    postEvent({type: "client-fail", msg,
+    postEvent({type: "client-fail", jsv: JSV, msg,
       ua: navigator.userAgent,
       hls_lib: typeof window.Hls,
       mse: (window.Hls && Hls.isSupported) ? Hls.isSupported() : null,
@@ -877,7 +879,7 @@ async function play(ep_id, ep_no) {
     try {
       const nativeOK = (() => { try { return document.createElement("video").canPlayType("application/vnd.apple.mpegurl") || "none"; } catch { return "err"; } })();
       const mse = (() => { try { return (window.Hls && Hls.isSupported) ? Hls.isSupported() : null; } catch { return "err"; } })();
-      postEvent({type: "play-probe",
+      postEvent({type: "play-probe", jsv: JSV,
         branch: (!window.Hls || !Hls.isSupported()) ? (nativeOK !== "none" && nativeOK !== "" ? "native" : "none-throw") : "hlsjs",
         hls_lib: typeof window.Hls,
         mse, native_hls: nativeOK, ua: navigator.userAgent});
diff --git a/static/index.html b/static/index.html
index f4c0269..c8784a1 100644
--- a/static/index.html
+++ b/static/index.html
@@ -6,7 +6,7 @@
 <title>ani-web</title>
 <link rel="icon" href="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 64 64'%3E%3Crect width='64' height='64' rx='14' fill='%23f97316'/%3E%3Ctext x='32' y='45' font-family='sans-serif' font-size='42' font-weight='700' text-anchor='middle' fill='%230e0f13'%3Ea%3C/text%3E%3C/svg%3E">
 
-<link rel="stylesheet" href="style.css?v=9">
+<link rel="stylesheet" href="style.css?v=10">
 </head>
 <body>
 <header>
@@ -30,6 +30,6 @@
      max-age=300 in browser AND possibly in your HTTPS proxy, and a stale
      copy is exactly how users keep seeing an old UI after a deploy -->
 <script src="hls.min.js"></script>
-<script src="app.js?v=9"></script>
+<script src="app.js?v=10"></script>
 </body>
 </html>