`greetd`

A login screen for greetd: when Strand runs as greetd's greeter, its socket ($GREETD_SOCK) logs a user in and starts their session. greetd's PAM conversation shows as it goes (prompt, message), and each answer is wiped once sent. Once a session starts, Strand exits so greetd can run it.

Field	Type
`available`	`bool`	greetd answers: Strand runs as its greeter. False otherwise, when every action fails with `error`.
`user`	`text`	The user being logged in (`greetd.login(user)`), or "".
`prompt`	`text`	What greetd asks ("Password: "), as PAM says it; "" while it asks nothing.
`echo`	`bool`	The answer to `prompt` may be shown as it is typed (a visible question, such as a name), not a secret one.
`message`	`text`	What PAM last told the user ("Place your finger on the fingerprint reader", "You are required to change your password"), or "".
`busy`	`bool`	greetd is busy with a request: checking an answer, starting the session.
`failed`	`bool`	The last answer was refused (greetd then asks the same user again), or a login or session could not start; `error` says why. It stays until the next answer or login.
`error`	`text`	Why the last request failed, as greetd says it, or "".

Method
`action login(user: text)`	Starts logging `user` in (a login already under way is dropped): greetd then asks its questions through `prompt`.
`action submit(answer: text)`	Answers `prompt` with `answer`: `input { type: password; text: <-> pw; on activate { greetd.submit(pw); pw = "" } }`. One typed after `login(user)` before greetd asks answers its first question when that one is secret (not `echo`), and is dropped when it is visible; one typed while an answer is checked, or after a text PAM showed, is dropped. Pass a password to nothing else: the config is trusted code, and a declared action's arguments can be read by every user in the process list. Only a greetd that root (or Strand's own user) serves is answered.
`action start(command: [text])`	Starts `command` as the user's session (`["sway"]`) once the login succeeds: called with the last answer, it waits for greetd to accept it; a login that fails drops it. Strand then exits. Each word is one word, as given (`["sh", "-c", "sway > log"]` for a shell line); greetd runs it after the user's `~/.profile`.
`action cancel()`	Drops the login under way.