Chart fonts: self-hosted roster + document.fonts.load render gate

vite.config.ts

@@ -56,13 +56,44 @@ export default defineConfig({
         ],
       },
       workbox: {
-        // Workbox's default globPatterns omit woff2; add it so the self-hosted
-        // Plex fonts are precached too (offline is a core requirement — without
-        // this the first offline load silently falls back to system fonts).
-        globPatterns: ['**/*.{js,css,html,ico,png,svg,woff2}'],
+        // Precache the app, plus the font woff2 the offline-first UI and the
+        // common chart path need:
+        //  - the bare `latin` subset of every family (`*-latin-[0-9]*` — the
+        //    weight digit excludes `latin-ext`), the common chart case;
+        //  - every subset of the UI fonts (IBM Plex Sans + Mono) — these are
+        //    capability: the chrome must render any script (incl. latin-ext,
+        //    Cyrillic, Greek) offline. The Sans brace-list names the subsets so
+        //    it matches the UI Sans but not `ibm-plex-sans-condensed-*`, a roster
+        //    chart font that stays latin-only like the rest.
+        // Every other subset (the roster's latin-ext and non-latin scripts) is
+        // decoration with per-glyph fallback: left out of the precache and
+        // runtime-cached on first use below, so the install stays small while the
+        // roster still works offline once a script has been seen. (Default
+        // globPatterns omit woff2 entirely — without this the first offline load
+        // silently falls back to system fonts.)
+        globPatterns: [
+          '**/*.{js,css,html,ico,png,svg}',
+          '**/*-latin-[0-9]*.woff2',
+          '**/ibm-plex-sans-{latin,latin-ext,cyrillic,cyrillic-ext,greek,greek-ext,vietnamese}-*.woff2',
+          '**/ibm-plex-mono-*.woff2',
+        ],
         // Monaco and Vega vendor chunks exceed Workbox's 2 MiB default; raise the
         // ceiling so the whole app (offline is a core requirement) is precached.
         maximumFileSizeToCacheInBytes: 6 * 1024 * 1024,
+        runtimeCaching: [
+          {
+            // Chart-roster non-latin font subsets: not precached, so fetch on
+            // demand and keep them offline-after-first-use. Precached woff2
+            // (latin + Plex) are served from the precache and never reach here.
+            urlPattern: /\.woff2$/,
+            handler: 'CacheFirst',
+            options: {
+              cacheName: 'chart-font-subsets',
+              expiration: { maxEntries: 120, maxAgeSeconds: 60 * 60 * 24 * 365 },
+              cacheableResponse: { statuses: [0, 200] },
+            },
+          },
+        ],
       },
     }),
   ],