What do you think of the “bridge” idea to only implicitly visualize the resulting subject in the text editor (for sending, similar as in received messages) with a hyphen - like in below examples?
Do you still see any intricates?
The subject may look (be marked) the same way as in received messages, i.e. ending with a - but additionally with a grey background.
For regular chat messages, the written text in the editor could be prepended with a lock that indicates that the message is going to get encrypted.
-
🔒-Written text…
(Here the background and - hints to the canonical subject being used in the resulting autocrypted email.)
But in cases that an unencrypted email is going to be sent, the entered text would first be part of the subject and thus written with the grey background.
-
🔓 Written text... up to max subject length -further written text.
Entering a new line within in the “subject length” could manually end the subject, at any time, allowing to thoughtfully choose and write a subject (if desired).
The marking in the editor might even be with only the - at the end (without a gray background), to be less noticeable, but still visible. However, I think writting the text starting with a grey background would also provide more attention to when the message is going to be sent as plain-text, which is a nice effect.