Horizon · Palette

Anatomy

After actions that can be undone for a while: sent emails, payment runs, notices, access grants.
Wherever agents act for people. People need to know what they can still take back.
Not for actions that are always cheap to reverse, like editing a draft. A plain undo is enough there.

Window	Shows	Marked by
Until a time	The time it closes, and how long is left	A bar; ochre in the last 10 minutes
Until an event	What closes it: “until it is opened”	Words only
Always open	Reversible at any time	Viridian words
Closed	The time it became permanent	A lock, on surface 2

Undo is the person’s action. An undone action stays in the list, struck through, so nothing disappears without a trace.

Give each deadline as a time and as time left: “until 17:00 · 2 h 40 min left”.
Order by how soon each window closes, not by when the action happened.
Name what closes an event window: “until it is opened”.
Keep permanent actions in the list, so people see what is settled as well as what isn’t.

DoSay when the window closes, and put the undo beside it.

Don’tDon’t report an action as final while it can still be undone. People don’t know they still have a choice.

The horizon axis is decorative; every deadline is also in the action’s text.
Each undo is a button named for what it does: Unsend, Cancel run, Withdraw, Revoke.
Undoing announces the result, and the action stays in the list.
Urgency shows in words and with a lock, not only in ochre.