Fixes asset path. Prepares to bump version.

Author: wilkie

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@code-dot-org/ml-playground",
-  "version": "0.0.48",
+  "version": "0.0.49",
   "private": false,
   "repository": {
     "type": "git",

src/assetPath.ts

@@ -1,7 +1,22 @@
-(
-  global as unknown as Record<string, unknown>
-).__ml_playground_asset_public_path__ = './assets/';
-
+// Consumer-facing setter for the ml-playground asset base path.
+//
+// The function writes a single property on the shared page global,
+// which the main bundle reads at startup (see `setPublicPath.ts`) to
+// assign webpack's `__webpack_public_path__`. That assignment is what
+// controls image and chunk URLs at runtime.
+//
+// Ordering: call this BEFORE the ml-playground main bundle is loaded
+// (i.e. before `require('@code-dot-org/ml-playground')` or any import
+// that resolves through the main entry). Asset URLs are computed when
+// each asset module first evaluates, so a late call can't retroactively
+// rewrite them. The natural CommonJS pattern (`setAssetPath(...); const
+// ml = require('@code-dot-org/ml-playground'); ...`) is correct;
+// pure-ESM consumers should call this then `await import(...)` the
+// main entry.
+//
+// No module-init side effect on purpose — the fallback for "consumer
+// never set it" lives in `setPublicPath.ts` as `|| './'`, so there's
+// one place to look when chasing publicPath behavior.
 export const setAssetPath = (path: string): void => {
   (
     global as unknown as Record<string, unknown>

src/indexDev.tsx

@@ -1,4 +1,5 @@
 import './assetPath';
+import './setPublicPath';
 import {initAll, instructionsDismissed} from './index';
 import queryString from 'query-string';
 import {ModelDataToSave, SaveResponse} from './types';

src/indexProd.tsx

@@ -1 +1,2 @@
+import './setPublicPath';
 export {initAll, instructionsDismissed} from './index';

src/setPublicPath.ts

@@ -0,0 +1,33 @@
+// Wire the runtime asset-path global into webpack's publicPath.
+//
+// Image imports (e.g. `import bot from './ai-bot-body.png'`) and any
+// other webpack `asset` / `asset/resource` modules resolve their URLs
+// against webpack's runtime `publicPath`. The default is `'auto'`,
+// which infers the path from where the host page loaded the script —
+// not what we want when the package is embedded into a consumer like
+// apps's dashboard, which serves these images from a different base
+// path (e.g. `/blockly/media/skins/ailab/`).
+//
+// Webpack exposes `__webpack_public_path__` as a magic variable: any
+// assignment to it at runtime updates the publicPath used by
+// subsequently-evaluated asset modules. We pull the desired base from
+// the same global the dataset/manifest loader already uses
+// (`__ml_playground_asset_public_path__`), so the consumer has one
+// knob to turn.
+//
+// This module MUST be imported before any module that pulls in an
+// image — i.e. it should be the first import in the entry file.
+// ECMAScript guarantees depth-first evaluation order: when an entry
+// does `import './setPublicPath'; import './index';`, this module's
+// body runs to completion before `./index` starts evaluating, so all
+// downstream asset modules see the updated `__webpack_public_path__`.
+// `__webpack_public_path__` is a webpack magic variable: at build time
+// webpack rewrites assignments to it as updates to its runtime
+// `__webpack_require__.p`. ESLint doesn't understand this — it sees a
+// `let` with a single assignment and no read, hence the disables.
+/* eslint-disable prefer-const, @typescript-eslint/no-unused-vars */
+declare let __webpack_public_path__: string;
+__webpack_public_path__ =
+  (global as unknown as Record<string, string>)
+    .__ml_playground_asset_public_path__ || './';
+/* eslint-enable prefer-const, @typescript-eslint/no-unused-vars */

webpack.config.js

@@ -38,7 +38,14 @@ const commonConfig = {
           },
         },
         generator: {
-          filename: 'assets/images/[name][ext][query]',
+          // URLs resolve to `<__webpack_public_path__>images/<name>`
+          // at runtime. The consumer sets the public path via
+          // `__ml_playground_asset_public_path__` (see
+          // `src/setPublicPath.ts`); leaving an `assets/` prefix here
+          // would double up against consumer paths that already end
+          // in `assets/` or similar, so the prefix lives entirely on
+          // the consumer side.
+          filename: 'images/[name][ext][query]',
         },
       },
     ],