fix(node): the handshake ack dropped one app's directories

The ack was assembled from its own tuple of application names, a copy of the
daemon's `APP_DIR_KEYS`, and the two had drifted: the copy was missing
`helloworld`. So the reference application — the one that exists to prove a new
application needs no special-casing — was the single application whose
configured folders never reached a client, which made the plugin claim false
exactly where it is demonstrated.

Fixed by removing the copy rather than syncing it. The ack now emits whatever
`<app>_directories` the group context carries, and `_app_directories_ctx` is the
only thing that puts one there, so the two cannot disagree again. The transport
names an application in one place, `ALLOWED_APPS`, which is enforcement rather
than a directory list.

The client had the same fault one layer up: `group-page.js` read three names by
hand from the ack while the live-update path beside it was already generic. It
derives the map from the ack's own keys now, so the fix reaches the settings
pane instead of stopping at the wire.

A first attempt moved the list to `roster.py`, where directory *storage* lives,
and `test_helloworld_proves_the_plugin_claim.py` refused it: the roster, the ops,
the config and the root set must name no application at all. That test is the
architecture's own guard and it was right — the list belongs on the daemon, which
is what wires a group's context, and everything downstream is derived from it.

Two new tests, both verified to fail against the previous shape: the ack carries
an application the node names nowhere else, and the ack keeps no list of its own.
`test_the_lists_are_read_under_one_name_each` now asserts the shell names no
application rather than that it names exactly three.

Two stale comments went with it — the ack's, which described scalars removed in
07ff8b4, and the client's, which said those scalars still rode the wire for
MNP 1.0 peers that can no longer connect.

Full suite: 2258 passed, 4 skipped.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YVoHVCcfBqud6ZjG4db3y7

1 files changed, 19 insertions, 6 deletions

diff --git a/packages/meshbay-hub/tests/test_app_settings_plugin.py b/packages/meshbay-hub/tests/test_app_settings_plugin.py
index af86f12..940d975 100644
--- a/packages/meshbay-hub/tests/test_app_settings_plugin.py
+++ b/packages/meshbay-hub/tests/test_app_settings_plugin.py
@@ -256,15 +256,28 @@ def test_each_app_takes_a_list_of_directories(app, prop):
 
 def test_the_lists_are_read_under_one_name_each():
     """
-    One name per app on the ack — `<app>_directories`, always a list. A second
-    name for the same answer means a page that reads whichever it thinks of
-    first, and a node that fills only the other one empties a working tab.
+    One name per app on the ack — `<app>_directories`, always a list — and the
+    shell names none of them.
+
+    It read three by hand until 2026-09-10, and `helloworld` was not among them:
+    the app that exists to prove a new one needs no special-casing had its
+    directories dropped on arrival, which made the plugin claim false exactly
+    where it is demonstrated. An app the node knows about must be one this page
+    already handles, and the only way to guarantee that is to read the ack's own
+    keys instead of a list kept here.
+
+    A second *name* for the same answer would be the older fault: a page reading
+    whichever it thinks of first, and a node filling only the other one emptying
+    a working tab.
     """
     page = GROUP_PAGE.read_text(encoding="utf-8")
-    block = page[page.index("setAppDirectories({"):]
+    block = page[page.index("setAppDirectories("):]
     block = block[:block.index("setChatDirectory")]
-    assert "ack.video_directories" in block and "ack.music_directories" in block
-    assert "ack.photo_directories" in block
+    assert "endsWith('_directories')" in block, (
+        "the shell must derive the map from the ack's keys, not name apps")
+    for named in ("ack.video_directories", "ack.music_directories",
+                  "ack.photo_directories"):
+        assert named not in block, f"{named} is an application named by the shell"
     for gone in ("ack.video_root", "ack.audio_root", "ack.photo_roots"):
         assert gone not in block, f"{gone} is a second name for the same answer"