feat(client): HelloWorld, the reference application

2026-09-06T22:48:55Z

Every other test of the plugin architecture reads source for the *absence* of app names. That proves nobody wrote a special case for Videos; it cannot prove a genuinely new application works, because there was no new application. This is one. It stores directories, appears as a tab, has a settings pane and lists files, and the node has never heard its name outside a single allow-list entry. Two files and one registry line, which is the claim `docs/refactor-groups.md` §4.1 makes. It ships hidden behind `?dev=1` (`dev: true` in the registry, the same opt-in shape as transport.js's `?trace=1`). Registering it normally would put a toy app in every operator's group; not registering it would prove nothing, since registration is exactly what is claimed to be sufficient. **Adding it found two places where the claim was nearly true rather than true, and both are fixed by making the code less app-specific:** `group-settings.js` fell back to the whole registry when a group had no `enabled_apps` yet — which would have turned a hidden app on for everyone. It asks `availableApps()` now. `group-page.js` wrote out `videoDirectories` / `musicDirectories` / `photoDirectories` by hand, so a fifth app would have needed that file edited. It derives `Directories` from the registry. Neither was found by reading; both were found by adding the app, which is the whole reason it exists. Verified in a real Electron window as well as by the tests: hidden by default, present with the flag, offered its own settings section, and listing exactly the files under its configured folder and its subfolders — not the ones beside it. Co-Authored-By: Claude Opus 5 Claude-Session: https://claude.ai/code/session_011pvMdvLBG92jyhvD5pD6us

meshbay.git/packages/meshbay-hub/tests/test_helloworld_proves_the_plugin_claim.py, branch 0.14

feat(client): HelloWorld, the reference application