feat(hub): split the group UI into a pluggable "applications" architecture

GroupPage's 6620-line app.js carried Chat and Files wedged in directly, with
no way to add another group-level app without touching the shell itself. It
is now app.js (routing, non-group pages) plus nine focused files — apps.js
(the registry), chat-app.js, files-app.js, video-player.js, group-page.js
(the shell), group-settings.js, hub-client.js, icon.js and file-utils.js —
with docs/apps.md as the checklist for adding one (Videos/Music/Photos are
sketched there, not built).

Node side gained the matching enablement mechanism, mirroring
member_upload exactly: a roster setting, a signed apps_enabled op enforced
by _has_admin_authority, exposed in the handshake ack. Operators toggle
applications per group from Settings, which also gained a small reorder:
Invite, Pairing, Applications, Shared directories, Uploads, danger zone,
Your devices, Members.

Two bugs surfaced during the split, both missing an import across the new
file boundary and invisible to node --check or a module-load probe since
they only throw when the code path actually runs:

- group-page.js called onRefreshAuth on a stale-token handshake rejection,
  but app.js never imported refreshAccessToken from hub-client.js — so a
  brand new member (including a group's own creator) hit "Not a member of
  this group" and the retry silently failed, throwing before it could
  refresh the token.
- chat-app.js called getLocale() for message timestamps without importing
  it from i18n.js. Opening Chat on a group with real messages threw mid-
  render; uncaught, that appears to wedge Preact's render scheduler, so
  every button on the page stopped responding until reload.

Caught the second class of bug with a proper no-undef audit across all
split files (a temporarily installed ESLint 9, since the system one is too
old to parse this codebase's syntax) rather than trusting grep. 827 tests
pass; 6 new ones cover the apps_enabled policy.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016SF6RKNBKg9qejmoMJ9ybA

1 files changed, 27 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/transport.js b/packages/meshbay-hub/src/meshbay_hub/static/transport.js
index 2cdf15d..da98253 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/transport.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/transport.js
@@ -104,6 +104,7 @@ class MeshBayTransport {
   set onStreamError(fn) { this._onStreamError = fn; }
   set onIndexSync(fn) { this._onIndexSync = fn; }
   set onUploadPolicy(fn) { this._onUploadPolicy = fn; }
+  set onAppsEnabled(fn) { this._onAppsEnabled = fn; }
 
   get sessionKeys() { return this._sessionKeys; }
 
@@ -613,6 +614,26 @@ class MeshBayTransport {
     return msg;
   }
 
+  /**
+   * Turn a group "application" (Chat, Files, ...) on or off for everyone.
+   *
+   * Takes the whole set in one signed message rather than one op per app, so
+   * ticking several boxes in Settings costs one signature. `apps` is sorted
+   * and joined the same way on the node before it is shown for signing —
+   * `_authorizeAdminOp` below checks the two match.
+   */
+  async setAppsEnabled(apps, signFn) {
+    const msg = await this._sendAndWait({
+      type: 'apps_enabled', v: '0.1', apps,
+    });
+    if (msg.type === 'error') throw new Error(msg.detail);
+    if (msg.type === 'admin_challenge') {
+      return this._authorizeAdminOp(
+        msg, 'apps_enabled', [...apps].sort().join(','), signFn);
+    }
+    return msg;
+  }
+
   async revokeMember(userId, signFn) {
     const msg = await this._sendAndWait({
       type: 'member_revoke', v: '0.1', user_id: userId,
@@ -1224,6 +1245,12 @@ class MeshBayTransport {
       this._onUploadPolicy(Boolean(msg.allowed));
     }
 
+    // Same shape: the operator changed which apps are shown, and everyone
+    // connected hears about it without reconnecting.
+    if (msg.type === 'apps_enabled_ack' && this._onAppsEnabled) {
+      this._onAppsEnabled(msg.apps || []);
+    }
+
     if (msg.type === 'index_sync' && msg.entries) {
       if (this._onIndexSync) this._onIndexSync(msg);
       const oldest = this._pending.entries().next();