feat(omnium): Expose caplet manifests in background console

Add omnium.manifests.echo so users can install caplets from the console:
  await omnium.caplet.install(omnium.manifests.echo)

Changes:
- Create src/manifests.ts with echo caplet manifest using chrome.runtime.getURL
- Add echo-caplet.bundle to vite static copy targets
- Expose manifests in background.ts via omnium.manifests
- Update global.d.ts with manifests type and missing getCapletRoot

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: rekmarks

packages/omnium-gatherum/src/background.ts

@@ -20,6 +20,7 @@ import {
   makeChromeStorageAdapter,
 } from './controllers/index.ts';
 import type { CapletManifest, LaunchResult } from './controllers/index.ts';
+import { manifests } from './manifests.ts';
 
 defineGlobals();
 
@@ -154,6 +155,9 @@ async function main(): Promise<void> {
     getKernel: {
       value: getKernel,
     },
+    manifests: {
+      value: manifests,
+    },
     caplet: {
       value: harden({
         install: async (manifest: CapletManifest, bundle?: unknown) =>

packages/omnium-gatherum/src/global.d.ts

@@ -40,6 +40,18 @@ declare global {
      */
     getKernel: () => Promise<KernelFacade>;
 
+    /**
+     * Pre-defined caplet manifests for convenience.
+     *
+     * @example
+     * ```typescript
+     * await omnium.caplet.install(omnium.manifests.echo);
+     * ```
+     */
+    manifests: {
+      echo: CapletManifest;
+    };
+
     /**
      * Caplet management API.
      */
@@ -98,6 +110,19 @@ declare global {
       getByService: (
         serviceName: string,
       ) => Promise<InstalledCaplet | undefined>;
+
+      /**
+       * Get the root object presence for a caplet.
+       *
+       * @param capletId - The caplet ID.
+       * @returns A promise for the caplet's root object (as a CapTP presence).
+       * @example
+       * ```typescript
+       * const root = await omnium.caplet.getCapletRoot('com.example.echo');
+       * const result = await E(root).echo('Hello!');
+       * ```
+       */
+      getCapletRoot: (capletId: string) => Promise<unknown>;
     };
   };
 }

packages/omnium-gatherum/src/manifests.ts

@@ -0,0 +1,37 @@
+import type { CapletManifest } from './controllers/caplet/types.ts';
+
+/**
+ * Get the extension URL for a bundle file.
+ *
+ * @param bundleName - Name of the bundle file (e.g., 'echo-caplet.bundle')
+ * @returns chrome-extension:// URL string
+ */
+function getBundleUrl(bundleName: string): string {
+  return chrome.runtime.getURL(bundleName);
+}
+
+/**
+ * Manifest for the echo-caplet.
+ *
+ * This Caplet provides a simple "echo" service that returns
+ * the input message with an "Echo: " prefix.
+ *
+ * Usage:
+ * - Provides: "echo" service
+ * - Requests: No services (standalone)
+ */
+export const echoCapletManifest: CapletManifest = harden({
+  id: 'com.example.echo',
+  name: 'Echo Service',
+  version: '1.0.0',
+  bundleSpec: getBundleUrl('echo-caplet.bundle'),
+  requestedServices: [],
+  providedServices: ['echo'],
+});
+
+/**
+ * All available caplet manifests for use in the console.
+ */
+export const manifests = harden({
+  echo: echoCapletManifest,
+});

packages/omnium-gatherum/vite.config.ts

@@ -38,6 +38,8 @@ const staticCopyTargets: readonly (string | Target)[] = [
   'packages/omnium-gatherum/src/manifest.json',
   // Trusted prelude-related
   'packages/kernel-shims/dist/endoify.js',
+  // Caplet bundles
+  'packages/omnium-gatherum/src/vats/echo-caplet.bundle',
 ];
 
 const endoifyImportStatement = `import './endoify.js';`;