fix(hub): keep an unmatched admin_challenge visible, add trace logging

A real report showed audio_root timing out with *nothing* logged in
between the connection handshake and the timeout — no admin_challenge, no
error, nothing. The previous fix made an unmatched admin_challenge return
silently (correctly, to stop it stealing an unrelated pending request —
see the earlier commit), but that silence is indistinguishable from "the
request never reached the node at all", which is exactly the ambiguity
blocking this investigation. An unmatched admin_challenge is now logged
(op, op_id, and the full set of currently-pending keys) instead of
dropped quietly, and setAudioRoot/_authorizeAdminOp trace both hops of
the round trip explicitly. Node-side, _do_audio_root gets a debug log at
entry — cheap, and the only way to know from server logs alone whether
the request was ever received if the client-side trail comes up empty.

Diagnostic only: no routing behavior changed from the previous fix,
verified against the same reproduction script.

1 files changed, 2 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
index a5cccaa..6d21175 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
@@ -1862,6 +1862,8 @@ class WebRTCPeerSession:
     def _do_audio_root(self, msg: dict) -> None:
         """Same shape as _do_video_root above — the Music app's own entry point."""
         path = msg.get("path")
+        log.debug("audio_root request user=%s path=%r",
+                 (self._user_id or "?")[:8], path)
         if not isinstance(path, str):
             self._send({"type": "error", "detail": "Missing or invalid 'path'"})
             return