From 3c7251bd53092d5424be78dbabf59ab26ee0d489 Mon Sep 17 00:00:00 2001
From: Peter Todd <ptr.tdd@gmail.com>
Date: Mon, 22 Jun 2026 13:00:52 +0100
Subject: [PATCH] Build codec worker as standalone artifact

---
 .changeset/solid-codec-worker.md  |  5 ++
 packages/zarrextra/README.md      |  3 +-
 packages/zarrextra/package.json   |  6 +--
 packages/zarrextra/vite.config.ts | 88 +++++++++++++++++--------------
 4 files changed, 58 insertions(+), 44 deletions(-)
 create mode 100644 .changeset/solid-codec-worker.md

diff --git a/.changeset/solid-codec-worker.md b/.changeset/solid-codec-worker.md
new file mode 100644
index 00000000..23dabbad
--- /dev/null
+++ b/.changeset/solid-codec-worker.md
@@ -0,0 +1,5 @@
+---
+"zarrextra": patch
+---
+
+Build the codec worker as a self-contained artifact for Vite consumers.
diff --git a/packages/zarrextra/README.md b/packages/zarrextra/README.md
index 7b2532cd..8317b608 100644
--- a/packages/zarrextra/README.md
+++ b/packages/zarrextra/README.md
@@ -119,4 +119,5 @@ required for that path.
 
 Optional dependencies: `@fideus-labs/fizarrita`, `@fideus-labs/worker-pool`,
 `@cornerstonejs/codec-openjpeg`, and `@cornerstonejs/codec-openjph` (bundled into
-the worker script).
+the default worker script). Future worker entries may let applications opt into
+lighter worker bundles when JP2K or HTJ2K codecs are not needed.
diff --git a/packages/zarrextra/package.json b/packages/zarrextra/package.json
index ae032b78..b3fdaa90 100644
--- a/packages/zarrextra/package.json
+++ b/packages/zarrextra/package.json
@@ -18,14 +18,12 @@
       "import": "./dist/codec-worker.js"
     }
   },
-  "files": [
-    "dist"
-  ],
+  "files": ["dist"],
   "publishConfig": {
     "access": "public"
   },
   "scripts": {
-    "build": "vite build",
+    "build": "vite build && vite build --mode codec-worker",
     "dev": "vite build --watch",
     "test": "vitest run",
     "test:watch": "vitest",
diff --git a/packages/zarrextra/vite.config.ts b/packages/zarrextra/vite.config.ts
index 3597ca50..8d533876 100644
--- a/packages/zarrextra/vite.config.ts
+++ b/packages/zarrextra/vite.config.ts
@@ -1,50 +1,60 @@
 import { resolve } from 'node:path';
-import { defineConfig } from 'vitest/config';
 import dts from 'vite-plugin-dts';
+import { defineConfig } from 'vitest/config';
 
 const pkgExternals = ['zarrita', '@fideus-labs/fizarrita', '@fideus-labs/worker-pool'];
 
-export default defineConfig({
-  plugins: [
-    dts({
-      outDir: 'dist',
-      include: ['src'],
-      exclude: ['**/*.test.ts', 'src/workers/codec-worker.ts'],
-    }),
-  ],
-  build: {
-    lib: {
-      entry: {
-        index: resolve(__dirname, 'src/index.ts'),
-        workers: resolve(__dirname, 'src/workers/index.ts'),
-        'codec-worker': resolve(__dirname, 'src/workers/codec-worker.ts'),
+export default defineConfig(({ mode }) => {
+  const isCodecWorkerBuild = mode === 'codec-worker';
+
+  return {
+    plugins: [
+      !isCodecWorkerBuild &&
+        dts({
+          outDir: 'dist',
+          include: ['src'],
+          exclude: [
+            '**/*.test.ts',
+            'src/workers/codec-worker.ts',
+            'src/workers/codec-worker-init.ts',
+          ],
+        }),
+    ],
+    build: {
+      emptyOutDir: !isCodecWorkerBuild,
+      lib: {
+        entry: isCodecWorkerBuild
+          ? resolve(__dirname, 'src/workers/codec-worker.ts')
+          : {
+              index: resolve(__dirname, 'src/index.ts'),
+              workers: resolve(__dirname, 'src/workers/index.ts'),
+            },
+        formats: ['es'],
+        fileName: isCodecWorkerBuild ? () => 'codec-worker.js' : undefined,
       },
-      formats: ['es'],
-    },
-    rollupOptions: {
-      external(id, parentId) {
-        if (parentId?.includes('codec-worker')) {
-          return false;
-        }
-        if (parentId?.includes('workers')) {
+      rollupOptions: {
+        external(id) {
+          if (isCodecWorkerBuild) {
+            return false;
+          }
           return pkgExternals.includes(id);
-        }
-        return id === 'zarrita';
-      },
-      output: {
-        entryFileNames: '[name].js',
+        },
+        output: {
+          codeSplitting: isCodecWorkerBuild ? false : undefined,
+          entryFileNames: '[name].js',
+        },
       },
+      sourcemap: true,
+      target: 'es2022',
     },
-    sourcemap: true,
-    target: 'es2022',
-  },
-  test: {
-    globals: true,
-    environment: 'node',
-    include: ['tests/**/*.spec.ts'],
-    coverage: {
-      provider: 'v8',
-      reporter: ['text', 'json', 'html'],
+    test: {
+      globals: true,
+      environment: 'node',
+      include: ['tests/**/*.spec.ts'],
+      coverage: {
+        provider: 'v8',
+        reporter: ['text', 'json', 'html'],
+      },
     },
-  },
+  };
 });