fix(client): degrade against a node still speaking MNP 1.0

The SPA is served by the hub, so deploying the hub puts this client in front of
every node — including the ones not updated yet. That window is the normal
state for as long as an operator takes, and for a node someone else runs it may
be indefinite. Three controls were broken across it, and the failure mode is
quiet: an unknown message type is logged by the node and never answered, so the
click produces a thirty-second wait ending in a timeout with nothing on screen
to say the node simply cannot do this.

Files' Upload button read `root.writable`, which a 1.0 node does not send — it
says `upload`, the same answer under the older name. The button disappeared on
every un-upgraded node. It reads both now, and still respects an explicit
`writable: false` rather than falling through to the legacy flag.

The per-app folder pickers spoke `app_directories`. Videos, Music and Photos
each had their own message before that and those still work, so the page
chooses by version: an operator on an older node keeps the ability they had.
`video_root` and `audio_root` hold one folder, so several are refused with a
reason rather than stored as the first and silently truncated.

Root management — writable, removable, eject, plug — has no older equivalent to
route to, so the table goes read-only with a line saying why and pointing at
the `meshbay-node root` commands. Chat's two settings are new with nothing
before them and are hidden the same way.

None of this was inferred from a payload's shape: `_checkNodeVersion` already
parsed the node's version and threw it away, and it is kept now. Coupling a
capability to whether some field happens to be present is how a flag flips
because an unrelated payload changed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011pvMdvLBG92jyhvD5pD6us

1 files changed, 53 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 785b926..32f8539 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/transport.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/transport.js
@@ -335,6 +335,25 @@ class MeshBayTransport {
   set onIndexDelta(fn) { this._onIndexDelta = fn; }
   set onUploadPolicy(fn) { this._onUploadPolicy = fn; }
   set onRootsChanged(fn) { this._onRootsChanged = fn; }
+
+  /** The MNP version the connected node declared, or '' before a handshake. */
+  get nodeVersion() { return this._nodeVersion || ''; }
+
+  /**
+   * Whether the node speaks the per-root and per-app operations MNP 1.1 added:
+   * `root_update`/`root_eject`/`root_plug`, `app_directories`,
+   * `chat_directory`, `chat_link_preview`.
+   *
+   * An older node has no equivalent for the root ones at all, and answers the
+   * app ones through their three predecessors (`video_root`, `audio_root`,
+   * `photo_roots`). The caller chooses which; what it must not do is send a
+   * 1.1 message and wait, because an unknown type is logged and dropped.
+   */
+  get supportsAppOps() {
+    const m = /^(\d+)\.(\d+)$/.exec(this._nodeVersion || '');
+    if (!m) return false;
+    return (Number(m[1]) > 1) || (Number(m[1]) === 1 && Number(m[2]) >= 1);
+  }
   set onAppsEnabled(fn) { this._onAppsEnabled = fn; }
   set onAppDirectories(fn) { this._onAppDirectories = fn; }
   set onChatDirectory(fn) { this._onChatDirectory = fn; }
@@ -600,6 +619,12 @@ class MeshBayTransport {
       // block, because everything below — the join, the proof, the sealed ack
       // — assumes both sides mean the same thing by each message.
       _checkNodeVersion(reply);
+      // Kept, not just checked. Several controls exist only on a node new
+      // enough to have them, and the alternative to asking is offering a
+      // button whose message an older node logs as unknown and never answers
+      // — a 30-second wait ending in a timeout, with nothing on screen to say
+      // the node simply cannot do this.
+      this._nodeVersion = String(reply.v || '');
       if (!window.MeshBayCrypto) {
         throw new Error('Node requires GEK proof but no crypto available');
       }
@@ -1195,6 +1220,34 @@ class MeshBayTransport {
    * Cleaned and sorted the same way the node does, so both sides build the
    * same bytes to sign.
    */
+  /**
+   * The same instruction a node too old for `app_directories` understands.
+   *
+   * Videos, Music and Photos each had their own message before this, and they
+   * still work — so an operator on an un-upgraded node keeps the ability they
+   * had, rather than being handed a control that silently times out. Chat has
+   * no predecessor, which is why its settings are hidden rather than routed.
+   */
+  async setAppDirectoriesLegacy(appKey, directories, signFn) {
+    const clean = [...new Set(
+      (directories || []).map((d) => (d || '').replace(/^\/+|\/+$/g, '')).filter(Boolean),
+    )].sort();
+    if (appKey === 'photo') return this.setPhotoRoots(clean, signFn);
+    // One folder was all these two could carry. Sending several would store
+    // the first and silently drop the rest, so it is refused instead.
+    if (clean.length > 1) {
+      throw new Error(
+        'This node is older than this page and can hold one folder per app. '
+        + 'Update it, or choose a single folder.');
+    }
+    const one = clean[0] || '';
+    if (appKey === 'video') return this.setVideoRoot(one, signFn);
+    if (appKey === 'music') return this.setAudioRoot(one, signFn);
+    throw new Error(
+      'This node is older than this page and cannot store this app\'s '
+      + 'folders. Its operator has to update it.');
+  }
+
   async setAppDirectories(appKey, directories, signFn) {
     const clean = [...new Set(
       (directories || []).map((d) => (d || '').replace(/^\/+|\/+$/g, '')).filter(Boolean),