wijjit_ssh.backend

A TerminalBackend bridged to an SSH channel.

This is the whole reason the backend seam exists: RemoteTerminalBackend runs an ordinary Wijjit app against an asyncssh session instead of the local console. It:

  • writes rendered frames and screen-control sequences to the SSH channel,

  • decodes inbound channel bytes into Wijjit key/mouse events on the event loop (see wijjit_ssh.input), so every element behaves exactly as it does locally, and

  • reports the client’s negotiated PTY size (refreshed on SIGWINCH-style resize events) as a task-local override, so many differently-sized sessions coexist in one server process.

It sets owns_terminal = False so the event loop installs none of the process-global terminal machinery (SIGTERM/SIGHUP/atexit restore, SIGTSTP suspend) - there is no local tty to restore, and those handlers are process-global and would collide across concurrent sessions.

The channel is opened in binary mode (encoding=None on the server), so inbound data arrives as raw bytes for the decoder and outbound frames are encoded here, at the one boundary where text becomes wire bytes.

class wijjit_ssh.backend.RemoteTerminalBackend(chan, columns, lines)[source]

Bases: TerminalBackend

Terminal backend that drives a Wijjit app over an SSH channel.

Parameters:

  • chan (asyncssh.SSHServerChannel) – The client’s session channel; frames are written here.

  • columns (int) – Initial terminal width negotiated by the PTY request.

  • lines (int) – Initial terminal height negotiated by the PTY request.

property screen_output: TextIO | None

Stream the ScreenManager writes to.

Returns:

The output stream for screen-control sequences (alternate buffer, cursor visibility, title). None means “use sys.stdout”, matching ScreenManager’s default.

Return type:

TextIO or None

write_frame(data)[source]

Write a fully rendered frame to the terminal.

Parameters:

data (str) – The frame’s ANSI byte string (already diffed by the renderer).

Return type:

None

get_size()[source]

Return the current terminal size.

Returns:

(columns, lines).

Return type:

tuple of int

create_input_handler(*, enable_mouse, mouse_tracking_mode)[source]

Build this session’s input source.

Called once by Wijjit during construction. The instance is retained so feed() can route inbound channel bytes to it.

Parameters:

  • enable_mouse (bool) – Whether the app wants mouse tracking.

  • mouse_tracking_mode (MouseTrackingMode or None) – Requested tracking granularity.

Returns:

An input source fed by this channel’s byte stream.

Return type:

ChannelInputSource

feed(data)[source]

Push inbound channel bytes into the input decoder.

Parameters:

data (bytes) – Raw bytes received on the channel.

Return type:

None

Notes

A no-op until the app has been constructed (which is what creates the input source), so data racing session startup is dropped rather than crashing the session.

resize(columns, lines)[source]

Record a new client terminal size.

The running event loop reads this via get_size() on its next frame and republishes it to the task-local size override, so overlays, notifications, and layout reflow to the new dimensions.

Parameters:

  • columns (int) – New terminal width.

  • lines (int) – New terminal height.

Return type:

None