feat(client): the platform seam, and an Electron shell that has never been run

Stage D, and the honest half of it.

D1 — the seam (done, and verified)
----------------------------------
`static/platform.js`. `HUB` becomes `platform.hubBase()` and the transport is
built with the same base, so one address has one source. In a browser it returns
'' and every path stays relative to the origin that served the page — the
acceptance criterion for this split was "the browser SPA behaves identically",
and it does. `platform.js` joins `_ASSETS`, or a change to it would not move the
content hash and a cached browser would never ask for it.

D2 — the shell (written, never launched)
-----------------------------------------
**There is no npm on this machine. Electron was never installed and
`packages/meshbay-client/` has not been run once.** That is stated here rather
than discovered later.

What is there: a main process serving the packaged interface over a privileged
`app://` scheme (`secure` and `standard` are not cosmetic — without them the
service worker refuses to register and streamed downloads break silently), a
preload exposing an enumerated bridge that never passes a filesystem path, a
window with `sandbox`, `contextIsolation` and no node integration, navigation
away from the package refused, and a CSP where the hub is reachable over
connect-src and is not a script source. The hub address arrives as a process
argument because `platform.hubBase()` runs before anything can await.

`test_desktop_shell.py` pins each of those by reading the source — the treatment
`test_downloads.py` already gives the three browser save paths. It catches a
property being removed and proves nothing about the application running. Two
were checked by breaking them.

The interface is *copied* into the package by `build/sync-ui.js` from the hub's
static directory, and `ui/` is gitignored: a silent fork is the only real way to
end up maintaining the interface twice.

D3 — partial
------------
The bridge, and the part worth having now: safeStorage's backend is reported
rather than assumed. On Linux it falls back to a fixed key when no keyring is
running, silently — someone who believes the OS is holding their keys is told
when it is not. The native key lifecycle belongs with D4 and needs a running
application to mean anything.

D8 — partial, and a real defect found
--------------------------------------
`meshbay-node.spec` installed the SYSTEM template — the one carrying `User=%i` —
into `%{_userunitdir}`. A user unit already runs as its owner and cannot carry
`User=`; systemd refuses the file, so the packaged unit could never have
started. Nothing noticed because nobody had built and installed the RPM.

Two units now: the template to `%{_unitdir}`, and a new `meshbay-node-user.service`
that a person enables themselves without a password — which is what lets the
desktop client install a node without asking for one. It carries ExecReload, so
`meshbay-node reload` does not have to stop a service somebody is streaming from,
and documents the drop-in for a drive outside the home, RequiresMountsFor
included.

798 tests pass; e2e.py still passes end to end. Nothing here was built or
launched: no npm, no rpmbuild.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/packages/meshbay-hub/tests/test_session_renewal.py b/packages/meshbay-hub/tests/test_session_renewal.py
index 38db67f..6c47f7a 100644
--- a/packages/meshbay-hub/tests/test_session_renewal.py
+++ b/packages/meshbay-hub/tests/test_session_renewal.py
@@ -28,6 +28,7 @@ broken client.
 import json
 import shutil
 import subprocess
+import re
 from pathlib import Path
 
 import pytest
@@ -223,5 +224,12 @@ def test_the_connection_signs_its_offer_with_a_live_token():
     assert "await ensureFreshToken()" in connect, (
         "the offer is signed with whatever token the effect captured, which is "
         "no longer refreshed by a re-run")
-    assert "new window.MeshBayTransport('', live)" in connect, (
-        "the transport is built with the captured token rather than the live one")
+    # Asserted on the argument, not on the whole call: the first argument is
+    # the hub's base URL and became configurable when the interface started
+    # shipping in a package. Pinning the literal made this fail for a change
+    # that had nothing to do with tokens.
+    built = re.search(r"new window\.MeshBayTransport\(([^)]*)\)", connect)
+    assert built, "the transport is not built in connect()"
+    args = [a.strip() for a in built.group(1).split(",")]
+    assert args[-1] == "live", (
+        f"the transport is built with {args[-1]!r} rather than the live token")