Every generated Remote method resolves to `RemoteResult<T>`, so the Gateway
client spec asserts the ok and error branches instead of the unwrapped value
and a throw, and the generator fixtures declare the wrapper in the consumer
face they typecheck. The RPC-failure test splits into the Host error carried
verbatim in the error branch plus a transport throw folded into it.
The runtime client, ui-command and ui-plan benches answer the generated
commands Remote through its result branches and provide the `remote.commands`
namespace their plugins now inject; the ui-command bench also serves the `$on`
the service subscribes on construction.
The directory-picker chooser mounts a backend and its surface as a pair, so the
real-Loader composition serves both surface packages and asserts each entry
arrives and leaves with its backend.
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