diff --git a/client/iconChunk.js b/client/iconChunk.js
new file mode 100644
index 000000000..61ed53cdd
--- /dev/null
+++ b/client/iconChunk.js
@@ -0,0 +1,18 @@
+// The chunk group that holds the lucide icons the app loads at startup (vite.config.js).
+//
+// Every lucide icon is a module of its own, and the plugin icon lookup
+// (src/components/shared/PluginIcon.tsx) reaches all of them by name, from the navigation
+// every page renders. Left to itself the bundler puts each icon that some other chunk
+// also uses into a chunk of its own, so that neither side holds a copy: 187 files of a few
+// hundred bytes each, every one a request of its own on a first visit and an entry of its
+// own in the service worker's precache. In one group they are one file, whose hash changes
+// only when lucide-react does.
+//
+// `tags: ['$initial']` for the reason the other groups carry it: without it the group would
+// also take icons that today sit behind a lazy route and make them part of the first load.
+export const ICON_CHUNK = {
+  name: 'vendor-icons',
+  priority: 20,
+  tags: ['$initial'],
+  test: /[\\/]node_modules[\\/]lucide-react[\\/]/,
+};
diff --git a/client/tests/unit/pwa/iconChunk.test.ts b/client/tests/unit/pwa/iconChunk.test.ts
new file mode 100644
index 000000000..0d4a4e6fb
--- /dev/null
+++ b/client/tests/unit/pwa/iconChunk.test.ts
@@ -0,0 +1,33 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { describe, expect, it } from 'vitest';
+import { ICON_CHUNK } from '../../../iconChunk.js';
+
+describe('ICON_CHUNK', () => {
+  it('FE-ICON-CHUNK-001: takes every lucide module, on either path separator', () => {
+    expect(ICON_CHUNK.test.test('/app/node_modules/lucide-react/dist/esm/icons/chevron-down.js')).toBe(true);
+    expect(ICON_CHUNK.test.test('/app/node_modules/lucide-react/dist/esm/createLucideIcon.js')).toBe(true);
+    expect(ICON_CHUNK.test.test('C:\\app\\node_modules\\lucide-react\\dist\\esm\\icons\\map.js')).toBe(true);
+  });
+
+  it('FE-ICON-CHUNK-002: takes nothing else', () => {
+    expect(ICON_CHUNK.test.test('/app/node_modules/react/index.js')).toBe(false);
+    expect(ICON_CHUNK.test.test('/app/node_modules/lucide-react-native/dist/esm/icons/map.js')).toBe(false);
+    expect(ICON_CHUNK.test.test('/app/client/src/components/shared/PluginIcon.tsx')).toBe(false);
+    expect(ICON_CHUNK.test.test('/app/client/src/lucide-react/own.ts')).toBe(false);
+  });
+
+  it('FE-ICON-CHUNK-003: holds only what the first load already needs', () => {
+    // Without the tag the group would also collect icons that sit behind a lazy route
+    // and make them part of the first load (see the note on the groups in vite.config.js).
+    expect(ICON_CHUNK.tags).toEqual(['$initial']);
+    expect(ICON_CHUNK.name).toBe('vendor-icons');
+  });
+
+  it('FE-ICON-CHUNK-004: vite.config.js lists it among the chunk groups', () => {
+    const config = readFileSync(resolve(process.cwd(), 'vite.config.js'), 'utf8');
+    const groups = config.slice(config.indexOf('groups: ['));
+    expect(config).toContain("import { ICON_CHUNK } from './iconChunk.js'");
+    expect(groups).toMatch(/groups: \[[\s\S]*?\n {12}ICON_CHUNK,\n/);
+  });
+});
diff --git a/client/vite.config.js b/client/vite.config.js
index af4661cbc..ff771d48e 100644
--- a/client/vite.config.js
+++ b/client/vite.config.js
@@ -4,6 +4,7 @@ import { VitePWA } from 'vite-plugin-pwa';
 import { visualizer } from 'rollup-plugin-visualizer';
 import { rtlTextAlias, plyrSpriteAlias } from './rtlTextAlias.js';
 import { withoutRuntimeFonts } from './bookFontPrecache.js';
+import { ICON_CHUNK } from './iconChunk.js';
 import { readFileSync } from 'node:fs';
 
 // The version this bundle is built as, baked in at build time. The Docker build
@@ -70,7 +71,8 @@ export default defineConfig(({ mode }) => ({
         // offline-first travel planner a route the user never opened before losing
         // signal still has to work. The trade is that splitting buys first paint and
         // not install size: 107 entries / 17,795 KiB before any of it, 463 /
-        // 23,292 KiB now (measured, not estimated).
+        // 23,292 KiB after it, and 460 / 59,426 KiB as of 5.1.2 with the icons in
+        // one chunk (iconChunk.js; 652 entries without it). All measured, not estimated.
         //
         // Keep this figure honest. #2228 traced PWA boot failures to the browser
         // evicting this origin's whole bucket, precached shell included, and this
@@ -350,6 +352,7 @@ export default defineConfig(({ mode }) => ({
               tags: ['$initial'],
               test: /[\\/]node_modules[\\/](zustand|dexie|axios|zod|dompurify|isomorphic-dompurify)[\\/]/,
             },
+            ICON_CHUNK,
           ],
         },
       },