Run the desktop's model layer in the browser (#557)

packages/platform/src/index.ts

@@ -1,13 +1,13 @@
 import { setPlatform } from "./registry";
 import { createTauriPlatform } from "./tauri";
 
-// Desktop is the only host today, so it is installed unconditionally and
-// synchronously — several modules call commands while the module graph is still
-// evaluating, so there is no later moment to do this in.
+// The desktop entry. Installed unconditionally and synchronously — several
+// modules call commands while the module graph is still evaluating, so there is
+// no later moment to do this in.
 //
-// This line is the swap point. A browser build selects its own host here, and
-// because nothing else in the app imports a host directly, that is the whole
-// change.
+// This line is the swap point, and a browser build swaps it by resolving the
+// package to `index.web.ts` instead of this file. Because nothing else in the
+// app imports a host directly, that is the whole change.
 setPlatform(createTauriPlatform());
 
 export * from "./capabilities";