build(web): split the shell dist into index and vendor chunks with langs/ and fonts/ dirs

apps/web/vite.config.ts

@@ -18,10 +18,101 @@ function rejectStandaloneServe(): Plugin {
   }
 }
 
+/**
+ * Vendor-chunk membership, by exact npm package name — the heavy render
+ * families (math, highlight, markdown) that change only on dependency bumps.
+ * Only packages workspace code imports DIRECTLY need listing: their private
+ * transitive dependencies (unified/hast/oniguruma machinery, ~50 packages)
+ * are imported solely by these and rollup's chunk coloring pulls them into
+ * vendor automatically. A dependency shared with index-side code falls back
+ * to index — a few kB of dilution, never a correctness problem. Anything not
+ * listed (react family, the vendored cordis workspace, tiny helpers like
+ * anser/clsx, all workspace code) stays in the default `index` chunk, so
+ * editing shell code re-hashes only index and returning clients keep the
+ * cached vendor chunk.
+ */
+const VENDOR_PACKAGES: ReadonlySet<string> = new Set([
+  // math
+  'katex',
+  'rehype-katex',
+  // syntax highlight (@shikijs/langs is handled separately below —
+  // lazy grammars must not land here)
+  'shiki',
+  // markdown pipeline
+  'react-markdown',
+  'remark-gfm',
+  'remark-math',
+  'mdast-util-from-markdown',
+  'mdast-util-gfm',
+  'micromark-extension-gfm',
+  'micromark-extension-math',
+  'micromark-factory-space',
+  'micromark-util-character',
+  'micromark-util-symbol',
+  'micromark-util-types',
+])
+
+/**
+ * Boot grammars statically imported by ui-primitives' highlight.ts
+ * (`@shikijs/langs/typescript` → `dist/typescript.mjs`, etc.). They live in
+ * the same package as the lazy read-card grammars, but unlike those they are
+ * part of the initial load and belong in the vendor chunk; the lazy ones must
+ * stay unassigned so each keeps its own on-demand chunk.
+ */
+const BOOT_GRAMMAR_FILES: readonly string[] = [
+  'dist/typescript.mjs',
+  'dist/shellscript.mjs',
+  'dist/json.mjs',
+]
+
+/** Font asset extensions routed to assets/fonts/ (KaTeX's woff2/woff/ttf faces today). */
+const FONT_EXTENSIONS: readonly string[] = ['.woff2', '.woff', '.ttf']
+
+/** npm package name of a resolved module id (the segment after the LAST `node_modules/` — pnpm nests the real package under an inner node_modules). */
+function npmPackageOf(id: string): string | undefined {
+  const parts = id.split('/node_modules/')
+  if (parts.length === 1) return undefined
+  const [first, second] = parts[parts.length - 1].split('/')
+  if (first.startsWith('.')) return undefined // .pnpm store segment, not a package
+  return first.startsWith('@') ? `${first}/${second}` : first
+}
+
 export default defineConfig({
   plugins: [rejectStandaloneServe(), react()],
   build: {
     sourcemap: true,
+    rollupOptions: {
+      output: {
+        // Output layout: the two main chunks stay at assets/ root; lazy
+        // @shikijs/langs grammar chunks group under assets/langs/; fonts
+        // (today all KaTeX faces referenced by vendor.css) group under
+        // assets/fonts/. Sourcemaps need no arrangement: rollup writes each
+        // .map next to its js and references it by bare relative filename.
+        chunkFileNames(chunk): string {
+          // Grammar chunks are recognized by their member modules, not the
+          // facade: shared embedded-grammar chunks (e.g. html+javascript,
+          // split out because php/ruby/mdx embed them) have no facade at all.
+          // index and vendor are excluded by name — vendor legitimately
+          // carries the three boot grammars.
+          if (chunk.name === 'index' || chunk.name === 'vendor') return 'assets/[name]-[hash].js'
+          const isLangChunk = chunk.moduleIds.some(id => id.includes('/node_modules/@shikijs/langs/'))
+          return isLangChunk ? 'assets/langs/[name]-[hash].js' : 'assets/[name]-[hash].js'
+        },
+        assetFileNames(asset): string {
+          const fileName = asset.names[0] ?? ''
+          const isFont = FONT_EXTENSIONS.some(ext => fileName.endsWith(ext))
+          return isFont ? 'assets/fonts/[name]-[hash][extname]' : 'assets/[name]-[hash][extname]'
+        },
+        manualChunks(id: string): string | undefined {
+          const pkg = npmPackageOf(id)
+          if (pkg === undefined) return undefined // workspace + vendored cordis: index
+          if (pkg === '@shikijs/langs') {
+            return BOOT_GRAMMAR_FILES.some(file => id.endsWith(`/${file}`)) ? 'vendor' : undefined
+          }
+          return VENDOR_PACKAGES.has(pkg) ? 'vendor' : undefined
+        },
+      },
+    },
   },
   resolve: {
     // Workspace packages resolve to SOURCE: package.json exports point at lib