Commit Graph
2 Commits
Author SHA1 Message Date
jaap-jan 0500e43e02 Stop the terminal's WebView painting over the setup screens
The shell layered its setup and unlock screens over the terminal, which does
not work: NativeWebView attaches a real Win32 child HWND through
NativeControlHost, and a child window composites above everything its parent
paints regardless of visual-tree z-order. The cards rendered sliced at the
terminal column's left edge; at the window's default width every one of their
buttons fell inside the WebView's rectangle, so the flow could only be
completed by keyboard, and a click in that region handed Win32 focus to
WebView2 so the text boxes silently stopped accepting keystrokes.

The WebView is now collapsed while the vault is not unlocked. The comment
that previously forbade this — hiding it means never realising it — was
wrong: NativeControlHost creates the native attachment on attach to the
visual tree, never consulting layout or visibility, and NativeWebView replays
a Source assigned before its adapter exists. A collapsed WebView still starts
WebView2, loads the page and lets the renderer attach. Confirmed: 35
msedgewebview2 processes with the control collapsed. What the first
connection after unlocking actually depends on is the existing await on
WaitForRendererAsync, since the data plane drops frames when no renderer is
attached.

Also fixes the second visible defect: the default server URL was
https://localhost:7217, the API's *second* launch profile, while the README,
its appsettings and a plain `dotnet run` all use http://localhost:5233 — so
nothing was listening, and an HTTPS client against a plaintext port reports
"The SSL connection could not be established", which reads as a certificate
problem. The default now matches, a missing scheme is rejected by name
instead of parsing as scheme "localhost", and that specific TLS failure now
suggests http://. Both new tests fail when the fixes are reverted.

Corrections to claims I made earlier and should not have:

- docs/platform-flags.md asserted the opposite of the mechanism above and
  cited an established msedgewebview2 connection as verification. That
  observation was taken while the overlay was showing but, because of this
  very bug, the WebView was uncovered and in plain view — so it confirmed
  only that a visible WebView is realised. A process-level check cannot
  verify a rendering claim. The entry was also filed under "Local cache".
- ITerminalHost was documented as the live seam the app plugs into, with a
  stub standing in for headless tests. It has no implementation anywhere and
  no test uses it; the view navigates the control directly. It also counted
  Avalonia.Controls.WebView and NativeWebView as two interchangeable
  backends when they are one component, with the Linux backend backwards.
- The README claimed the shell's whole path was covered by tests. Its state
  machine is; its layout is covered by nothing, and a headless test could
  not have caught this — headless has no native window, so it would have
  rendered correctly and confirmed the wrong belief.

Verified by screenshotting the running app: the card renders complete and
centred at the default size, with the button clickable.
2026-07-29 13:26:30 +02:00
jaap-jan eb354bcdd9 Add the SSH session layer and the terminal data plane
The throughput harness the plan requires before any UI, plus the SSH
plumbing under it. 94 new tests, no WebView involved.

Credit-based flow control is what makes `yes` survivable. A terminal renders
at 60 Hz at best while a remote produces output as fast as the network
allows, and the difference has to accumulate somewhere or be refused.
Credit is reserved *before* reading, never after: because the pump cannot
read more than the renderer has room for, the coalescing buffer is bounded
by the window rather than by how fast the remote can talk. When credit runs
out the pump stops reading, SSH's own receive window closes, and the remote
sshd blocks -- backpressure to the source with no custom protocol.

Verified by falsification, not just by passing: with the credit gate removed
three tests fail, including the throughput harness's bounded-memory
assertion. Acknowledgements are clamped because they cross into JavaScript,
where a buggy or hostile page could otherwise claim to have rendered a
gigabyte and talk the host into an unbounded read.

Host key trust is enforced by *failing* the connection rather than
prompting inside the handshake. SSH.NET raises verification synchronously,
so consulting the user there would block the handshake on a UI round trip
and deadlock the first time the prompt needed the UI thread. Unknown host
and changed key become distinct exceptions the caller resolves
asynchronously. A mismatch has no retry path at all: a dialog offering to
continue is how users are trained to click through the one warning that
actually indicates interception. A legitimately rebuilt server is handled by
removing the pin in settings, away from the moment of connecting.

The data plane serves the renderer page from the same loopback listener as
the socket, which makes Origin predictable -- always http://127.0.0.1:{port}
-- where a WebView virtual-host mapping would give a different origin per
backend and nothing to validate. The token is substituted at serve time, so
it never touches disk and never appears in a URL. Being clear about what
that buys: not protection from a process running as this user, which can
read our memory anyway, but from a page in the user's browser attempting
WebSocket connections to loopback ports, which is a real and routine thing.

Two bugs the tests caught. The accept loop handled connections serially, so
an upgraded WebSocket parked it inside the receive loop and every later
request went unanswered -- the page's own script among them. The suite hung
rather than failed, which is how I found it. And SHA-1 is unavoidable here:
RFC 6455 mandates it for Sec-WebSocket-Accept, where it authenticates
nothing. Suppressed narrowly with that reasoning; the alternative,
HttpListener.AcceptWebSocketAsync, throws PlatformNotSupportedException off
Windows.
2026-07-28 21:58:55 +02:00