Messaging

Messaging — SMS, MMS and Signal for e-ink screens, with a web page for texting from your own computer.

An SMS and MMS app for the Mudita Kompakt, restyled for the phone's e-ink screen, with two things bolted on that the phone cannot otherwise have: Desktop Sync, reading and replying from a browser on a computer, and Signal, in the same inbox as your texts.

Kotozute is 言伝 — word left with someone to carry the rest of the way. The 伝 is the one in 人づて (hitozute, by way of a person) and 伝える (to convey). It names what is handed over rather than the machinery that carries it, which is the point: the phone, the cell tower and the browser are all just the someone in the middle.

It continues QKSMS by way of QUIK, and branched off InkMessage, which is where the e-ink work started.

What it needs Nothing but the phone. Signal runs in the app: it holds a Signal identity of its own and talks to Signal's servers directly, with nothing in between.

There are two ways in, both under Settings → Signal.

Link this phone, which is the ordinary one. On a phone that already has your Signal, open Settings → Linked devices → Link new device, and scan the code this one shows — the same exchange that links Signal Desktop.

Register this number, for a phone that is the only Signal you have. This makes it become the account for that number: if that number is on Signal anywhere else, that stops working and its linked devices are dropped, and the messages already on the other phone stay there. It needs a number that can receive a text from a short code — Google Voice and most other internet numbers cannot, and neither can they take the call — and there is a "call me with the code instead" option for when the text does not come.

There is no push, so the app collects its own messages. Signal does not send notifications to anything but its own clients, so how quickly a message arrives is decided by Keep Signal connected. On, a foreground service holds the connection open and messages arrive as they are sent, at the cost of a permanent notification. Off, which is the default, Signal catches up every so often and when you open the app. Measured on the phone in forced deep idle, with the app backgrounded: with the switch on the message arrives, with it off nothing arrives until the next catch-up.

Threads start empty. Signal's servers do not hold history and a newly linked device is not sent any, so conversations fill from the day you pair. Importing a Signal Desktop export is how you get the rest.

What is not possible Worth saying plainly, so nobody goes looking:

No Signal calls. The app registers itself as carrying neither voice nor video, and there is no audio path in it. No PIN, registration lock, number change or account transfer. Linked to a phone that already has Signal, those all belong to that phone. Registered here, they are simply not implemented — registration is done without a registration lock, and setting one afterwards needs a client that supports it. A linked device dies with its primary. If the phone holding the Signal account is ever unregistered, this one stops with it. That does not apply if this phone registered the number itself, because then it is the primary. History does not arrive by itself. Signal's servers do not hold it and a newly linked device is not sent any, so threads start empty and fill from the day you pair. Importing an export is how you get the rest.