Add low-memory client concurrency guard

CHANGELOG.md

@@ -5,6 +5,11 @@ Follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) · versioned wi
 
 ---
 
+## [1.20.39] — 2026-08-19
+
+### Changed
+- **Low-memory devices now receive conservative batch concurrency.** Shared frontend worker pools cap themselves at two concurrent tasks when the browser reports approximately 4 GB RAM or less, reducing memory spikes during bulk operations.
+
 ## [1.20.38] — 2026-08-19
 
 ### Added

TODO.md

@@ -37,7 +37,7 @@ Priority levels:
 - [ ] Update only affected table rows instead of rebuilding entire tables.
 - [ ] Add an LRU cache for audio and images and remove old entries automatically.
 - [ ] Revoke discarded object URLs with `URL.revokeObjectURL(objectUrl)`.
-- [ ] Add low-memory mode using `navigator.deviceMemory` where available.
+- [x] Add low-memory mode using `navigator.deviceMemory` where available; shared worker pools cap at two tasks on devices reporting approximately 4 GB RAM or less.
 - [ ] Disable image preloading and reduce table/cache sizes on devices with approximately 4 GB RAM.
 
 ## P1 — Backend stability and bounded concurrency

VERSION

@@ -1 +1 @@
-1.20.38
+1.20.39

static/index.html

@@ -10,7 +10,7 @@
   <meta name="format-detection" content="telephone=no">
   <meta name="color-scheme" content="light dark">
   <meta name="theme-color" content="#2563EB">
-  <meta name="app-version" content="1.20.38">
+  <meta name="app-version" content="1.20.39">
   <link rel="manifest" href="/manifest.webmanifest">
   <link rel="icon" href="/static/icon.svg" type="image/svg+xml">
   <link rel="apple-touch-icon" href="/static/icon.svg">
@@ -27,7 +27,7 @@
 
   <!-- ── Core styles (local — no CDN dependency for first paint) ────────── -->
   <link rel="stylesheet" href="/static/vendor/mdi/materialdesignicons.min.css">
-  <link rel="stylesheet" href="/static/style.css?v=1.20.38">
+  <link rel="stylesheet" href="/static/style.css?v=1.20.39">
 
 
   <!-- ── Flag icons — non-blocking (loaded async, icons appear after JS) ── -->
@@ -378,7 +378,7 @@ window.toggleNavTree = function(treeId, chevronId) {
 </script>
 
 <!-- loader.js: fetches sections → loads JS modules → removes skeleton -->
-<script src="/static/loader.js?v=1.20.36"></script>
+<script src="/static/loader.js?v=1.20.39"></script>
 
 </body>
 </html>

static/js/utils.js

@@ -336,10 +336,20 @@ function debounce(fn, ms) { let t; return (...a) => { clearTimeout(t); t = setTi
 // Log a non-fatal error instead of silently swallowing it (was `.catch(()=>{})`).
 // Use in best-effort paths so failures are visible in the console for debugging.
 function logErr(context, err) { try { console.warn(`[${context}]`, err && (err.message || err)); } catch (_) {} }
+// Keep batch work conservative on small client devices. Desktop machines
+// without the Device Memory API keep the normal pool size; browsers that do
+// expose it get a hard cap before multiple audio/image requests can build up.
+function ttvcIsLowMemoryDevice() {
+  const memory = Number(globalThis.navigator?.deviceMemory);
+  return Number.isFinite(memory) && memory > 0 && memory <= 4;
+}
+window.ttvcIsLowMemoryDevice = ttvcIsLowMemoryDevice;
 // Run an async worker over items with bounded concurrency (default 4). `onProgress(done,total)`
 // fires after each item. Replaces slow serial `for…await` loops over network calls.
 async function runPool(items, worker, concurrency = 4, onProgress) {
   const arr = [...items]; let i = 0, done = 0; const total = arr.length;
+  const requested = Math.max(1, Number(concurrency) || 1);
+  const effectiveConcurrency = ttvcIsLowMemoryDevice() ? Math.min(2, requested) : requested;
   async function run() {
     while (i < arr.length) {
       const idx = i++;
@@ -347,7 +357,7 @@ async function runPool(items, worker, concurrency = 4, onProgress) {
       done++; if (onProgress) { try { onProgress(done, total); } catch (_) {} }
     }
   }
-  await Promise.all(Array.from({ length: Math.min(concurrency, arr.length) }, run));
+  await Promise.all(Array.from({ length: Math.min(effectiveConcurrency, arr.length) }, run));
 }
 async function copyText(text) {
   try {