WIP cosmic-session-lock-layer-v1 protocol

[ids1024]

A very rough draft of an implementation of a protocol to allow cosmic-bg to be shown on the lock-screen.

This could also be used by the panel, but we'll also need another protocol to notify the panel that the session is locked so it can hide applets that shouldn't be shown on the lock screen, and propagate that information to applets. That is more subtle to get right.

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[hojjatabdollahi]

I tried this with glowberry. But it doesn't redraw. Looks like it's short circuiting:

cosmic-comp/src/shell/mod.rs

Lines 2049 to 2055 in bb5f8b7

	if let Some(session_lock) = &self.session_lock {
	return session_lock
	.surfaces
	.iter()
	.find(|(_, v)| v.wl_surface() == surface)
	.map(|(k, _)| k);
	}

It needs to handle show-on-lock layer:

        if let Some(session_lock) = &self.session_lock {
            if let Some(output) = session_lock
                .surfaces
                .iter()
                .find(|(_, v)| v.wl_surface() == surface)
                .map(|(k, _)| k)
            {
                return Some(output);
            }
            // schedule redraw for commits by show-on-lock layers
            return self.outputs().find(|o| {
                layer_map_for_output(o)
                    .layer_for_surface(surface, WindowSurfaceType::ALL)
                    .is_some_and(|l| layer_show_on_lock(l.wl_surface()))
            });
        }

recording-2026-09-08_17-36-53-trimmed.mp4

[ids1024]

Yeah, there are a couple places that iterate over surfaces that still need to be updated.