Commit Graph
3 Commits
Author SHA1 Message Date
jaap-jan 095774c498 Take a returning renderer's socket over instead of refusing it
One attach per process was WebView2's truth, not Android's: the phone
kills the WebView's renderer independently of the app process, the page
reloads, and its fresh socket was answered 409 by a guard that never
reset — with no way back short of restarting the app. Only our own page
knows the token, so a second valid upgrade is that page returning; it
now displaces the old socket, which may never notice it is dead on its
own, since a killed renderer sends no FIN.

A send into the dead socket also no longer escapes as a fault. It used
to unwind the pump's flush loop, after which nothing drained the credit
window and the still-live shell froze behind it for good — including
the BCL quirk where such a send surfaces as an OperationCanceledException
nobody's token asked for.
2026-08-09 10:54:20 +02:00
jaap-janandClaude Opus 5 c00e5dbc5c Let the terminal's text be made bigger, and remember how big
ci / build and test (push) Successful in 1m12s
ci / android head (push) Failing after 4s
ci / api image (push) Successful in 24s
Taking pinch-zoom off the phone left nothing in its place, and there was nothing on the desktop
either. This is the replacement, and it is deliberately not the thing that was removed: zoom scales
what has already been drawn, so the remote goes on wrapping to a width that is no longer on screen.
Changing the font size refits the grid and reports the new column count, so the far end is told it
has fewer columns. That round trip is the feature.

The size is one number, owned by the shell. It has to be, for two reasons that pull the same way: it
must survive a relaunch, and it must be reachable from a phone that has no Ctrl key to press. So the
page asks and the host decides — a signed step over a new client opcode, answered with a size over a
new server opcode. The phone's buttons and the desktop's chords arrive at the same place, and a size
set by either is the size both remember.

Stored in settings.json beside the cache rather than in it, and that is not laziness about a
migration. The cache is encrypted and unreadable until a vault is unlocked, and the first terminal of
a locked launch needs the size already. Nothing secret may go in that file; ClientSettings says so
out loud, because the next person to add a preference is the one who needs to read it.

Where it is reachable from differs per head, and only here. The phone gets A− and A+ on the
connection line — not in the accessory row, which scrolls, and a control that fixes unreadable text
must never be the thing that is off-screen. The desktop gets the three chords every terminal
emulator has, answered by the page while a terminal has focus and by the window when it does not,
plus a row in preferences that shows the current value and names the chords rather than replacing
them. Someone whose terminal is too small to read is not in a position to go looking.

Clamped 8 to 32. Below eight a monospace grid stops being legible and becomes a texture, and every
column of it is still a column the remote is being told exists; above thirty-two a phone in portrait
has too few columns to hold a prompt. The buttons disable at the ends rather than accepting presses
that do nothing, which on a terminal reads as the application having stopped responding.

The preferences screen's header comment claimed none of the design's terminal settings could be
saved, and listed the three things that were missing to make one work. All three now exist, so it
says which one is real and why the other five still are not.

Verified with the protocol suite — including that the step byte round-trips signed, since read
unsigned a step down arrives as 255 and clamps to the largest font, making "smaller" do the most
dramatic available version of "larger" — a data-plane test that the chord is heard with no session
registered, and five shell tests: the default matches the renderer's, both clamps hold, reset works,
and a size chosen in one shell is there in a second one over the same profile directory. Layout
suite and both heads build.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-02 13:15:11 +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