Architecture

etrans is two crates in one workspace.

etrans-core

Everything that is not drawing, and has no UI dependency:

Module
`ssh`	Connecting: TCP or a tunnel through a jump host, the host key check, and the login (agent, keys, password, keyboard-interactive). Anything that needs a person is put to an `Asker`, and the connection waits for the answer.
`known_hosts`	`~/.ssh/known_hosts` read as OpenSSH reads it: patterns, negation, hashed names, `@revoked` and `@cert-authority`, and host certificates checked against it.
`ssh_config`	The parts of `~/.ssh/config` etrans uses.
`sftp`	The remote filesystem over an SFTP channel.
`local`	The local filesystem, listed the same way, plus keys in `~/.ssh` and user and group names.
`transfer`	The transfer queue: planning, copying with partial files and resume, retries, conflicts.
`forward`	Local, remote and SOCKS5 forwarding.
`shell`	An interactive shell in a pseudo-terminal.
`site`, `settings`, `secrets`, `import`, `accounts`	Saved servers, settings, Keychain, importing, owners by name.
`runtime`	The tokio runtime the SSH work runs on.

SSH and SFTP are russh and russh-sftp. russh needs tokio, and gpui has its own executor, so the two meet in runtime: work is spawned onto a runtime that lives for the whole process, and the caller gets back a plain future any executor can wait on. Dropping that future stops the work, which is how cancelling a connection really cancels it.

etrans

The app, on GPUI:

Module
`browser`	The main window: connecting and reconnecting, the server list, dialogs, the right-click menu, the transfer drawer, port forwarding, Get Info, About and the update strip.
`pane`	One file pane: listing, selection, navigation, drag and drop.
`terminal`	A shell window: alacritty's emulator fed from the SSH channel, drawn cell by cell.
`preferences`	Settings as the app holds them, and the Settings window.
`update`	The updater: the feed, the download, the signature check and the swap.
`text_input`, `ui`, `theme`, `actions`, `keys`	Text fields, shared controls, colours, actions and their keys, and keystrokes to terminal bytes.

Two things worth knowing

Questions from the background. A connection that meets an unknown host key, or needs a password, does not know about windows. It calls an Asker — a function from a Question to a future answer — and waits. The window turns the question into a sheet and sends the answer back over a oneshot channel. A reconnect wraps the asker in one that answers passwords typed earlier from memory.

Partial files are named for their source. A transfer writes .<name>.<size>-<mtime>.etrans-part beside the destination and renames it into place when it is whole. Resuming is looking for that exact name: if the source changed, the name changed, and the copy starts over instead of continuing a different file.