feat(import-bundle): Add typedImportBundle (instead of type on importBundle)

Author: kriskowal

packages/import-bundle/NEWS.md

@@ -6,6 +6,8 @@ User-visible changes to `@endo/import-bundle`:
   object that resembles a module exports namespace with the objects specified
   on the symbol-named property @exports, which is deliberately not JSON
   serializable or passable.
+- Exports a `typedImportBundle<ExpectedNamespaceType>` function so consumers
+  can subscribe to a narrower type.
 
 # v1.3.0 (2024-10-10)
 

packages/import-bundle/src/index.js

@@ -18,16 +18,8 @@ import { wrapInescapableCompartment } from './compartment-wrapper.js';
  * @typedef {import('@endo/bundle-source').BundleSourceResult<any> | {moduleFormat: 'test'}} ImportableBundle
  */
 
-/**
- * importBundle takes the output of `bundleSource` or `bundleTestExports`, and returns a namespace
- * object (with .default, and maybe other properties for named exports)
- *
- * @template [T=any]
- * @param {ImportableBundle} bundle
- * @param {object} [options]
- * @param {object} [powers]
- * @returns {Promise<T>}
- */
+// Adding a type signature in-place proved difficult to migrate in-place.
+// See typedImportBundle below.
 export async function importBundle(bundle, options = {}, powers = {}) {
   await null;
   const {
@@ -194,6 +186,22 @@ export async function importBundle(bundle, options = {}, powers = {}) {
   }
 }
 
+/**
+ * typedImportBundle<Expected> takes the output of `bundleSource` or
+ * `bundleTestExports`, and returns a namespace object, with .default, and
+ * maybe other properties for named exports.
+ *
+ * This is the intended signature but produces a type that is not suitable
+ * in integration with legacy code of Agoric SDK.
+ *
+ * @template [T=any]
+ * @param {ImportableBundle} bundle
+ * @param {object} [options]
+ * @param {object} [powers]
+ * @returns {Promise<T>}
+ */
+export const typedImportBundle = importBundle;
+
 /**
  * A utility function for producing test bundles, which are not serializable
  * as JSON or passable.