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, 18 insertions, 0 deletions

diff --git a/CLAUDE.md b/CLAUDE.md
index 7a944af..c117c5e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -338,6 +338,24 @@ anything that assumes one key per person.
   key from the per-node identities. What it does cost is metadata: the hub now
   knows how many devices an account has and when each last signed in
 
+- **The desktop client exists as source and has never been run.** There is no
+  npm on the development machine, so Electron was never installed and
+  `packages/meshbay-client/` has not been launched once. `test_desktop_shell.py`
+  pins its security contract by reading the source — sandbox, contextIsolation,
+  the privileged `app://` scheme, the CSP keeping `wasm-unsafe-eval`, the
+  traversal check, the bridge exposing no path. That is the same weak evidence
+  `test_downloads.py` gives the browser save paths, and for the same reason: it
+  catches a property being *removed*, and proves nothing about the thing running
+
+- **A user unit cannot carry `User=`.** `meshbay-node.spec` installed the system
+  template into `%{_userunitdir}`, where systemd refuses the file outright — the
+  packaged unit could never have started, and nothing noticed because nobody had
+  built and installed the RPM. Two units now, `test_packaging_units.py` holds
+  each in its own directory. Note the test's own first version searched the
+  whole file and matched the *comment* explaining why `User=` is absent; parse
+  directives, not text — the same mistake as reading a CSP out of the comment
+  above the meta tag
+
 ## Two lessons that cost four rounds of live testing
 
 - **`QE/deploy/e2e.py` cannot test `app.js`.** It is a second implementation of the