feat(mnp): sharing a folder is decided on the node's machine only (MNP 6.0)

root_add, root_update and group_attach leave MNP: adding a directory and
switching writable/removable go through the loopback API (native dialog in
the desktop app) or the CLI. The operator's Settings tab still lists the
roots from any browser, read-only. The desktop app refuses to sign those
ops; a loopback flag change now reaches open pages (publish_roots).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 26 insertions, 2 deletions

diff --git a/packages/meshbay-client/src/main.js b/packages/meshbay-client/src/main.js
index cbaabc4..0020084 100644
--- a/packages/meshbay-client/src/main.js
+++ b/packages/meshbay-client/src/main.js
@@ -2218,7 +2218,16 @@ function registerBridge() {
       await confirmFolder(body.path);
       return ['POST', target, body];
     },
-    updateRoot:       (a) => ['PATCH', root(a), anObject(a.updates)],
+    // Opening a folder to writes from every member is asked like sharing it;
+    // closing it, or the removable flag, only narrows.
+    updateRoot: async (a) => {
+      const updates = anObject(a.updates);
+      if (updates.writable === true) {
+        await confirmOrRefuse('native.root_writable_confirm',
+                              { name: aText(a.rootName, 'the folder name') });
+      }
+      return ['PATCH', root(a), updates];
+    },
     ejectRoot:        (a) => ['PUT', `${root(a)}/eject`],
     plugRoot:         (a) => ['PUT', `${root(a)}/plug`],
     removeRoot:       (a) => ['DELETE', root(a)],
diff --git a/packages/meshbay-client/src/transcripts.js b/packages/meshbay-client/src/transcripts.js
index 0b6d0c0..63f87b2 100644
--- a/packages/meshbay-client/src/transcripts.js
+++ b/packages/meshbay-client/src/transcripts.js
@@ -30,6 +30,21 @@ function lenPrefixed(prefix, parts) {
   return Buffer.concat(chunks);
 }
 
+// The signed operations this application asks a node to perform
+// (meshbay_common/adminop.py). A list, not a pattern: what widens a node's
+// sharing — `root_add`, `root_update`, `group_attach`, gone from MNP 6.0 — is
+// never signed here, so a node older than that cannot be driven into it by a
+// script in the page either.
+const ADMIN_OPS = new Set([
+  'file_delete', 'dir_delete', 'invite_create', 'invite_link_create',
+  'invite_cancel', 'member_revoke', 'member_unpin', 'gek_rotate',
+  'apps_enabled', 'set_scan_settings', 'transfer_limits', 'tmdb_config',
+  'tmdb_enabled', 'tmdb_override', 'tmdb_rematch', 'musicbrainz_enabled',
+  'root_remove', 'root_eject', 'root_plug', 'app_directories',
+  'chat_directory', 'chat_link_preview', 'search_listed', 'chat_epoch',
+  'group_detach',
+]);
+
 // ── Field checks ──────────────────────────────────────────────────────────
 //
 // Shapes, not trust: what is checked here is that a field is what its name
@@ -143,7 +158,7 @@ function transcriptFor(kind, f, ctx) {
     }
     case 'admin': {
       const op = String(fields.op ?? '');
-      if (!/^[a-z_]{1,32}$/.test(op)) refuse('not an operation');
+      if (!ADMIN_OPS.has(op)) refuse('not an operation');
       return lenPrefixed(PREFIX.admin, [
         enc(op), enc(sameNode()), enc(groupId(fields.groupId)),
         enc(text(fields.subject, 'the subject', 16384)),