sway-fader fades in containers on workspace focus and window new events.
Installation from release or from source:
go install github.com/mgnsk/sway-fader@latest
exec sway-fader
By default a rule of --class=".*:0.7:1.0" is applied which can be overridden by user specified flags.
Example config in ~/.config/sway/config to keep foot terminal transparent and other windows opaque:
exec sway-fader --app_id="foot:0.7:0.97"