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PTN·03·002

Undo vs Confirm

The mercy pattern traditional

Two ways to protect a person from their own click. Confirm interrupts before the act: are you sure? — asked so often that the honest answer becomes a reflex, and the reflex defeats the protection. Undo permits the act and holds the door open after it: done — undo? One pattern taxes every action to protect the rare mistake; the other taxes nothing and rescues the mistake itself.

The judgment of this floor: undo beats confirm wherever undo is possible. Gmail's send-undo did more for email regret than twenty years of confirmation dialogs. Confirm survives for the genuinely irreversible — deletion that truly deletes, payments that truly move — and for nothing else. A confirm guarding a reversible action is an interruption cosplaying as safety.

CONFIRM — pays before stop & ask the act UNDO — pays never, rescues after the act undo · 5s window
FIG 03·002 — where each pattern spends the user's attention.

Undo — use when

  • The action can be held, delayed, or reversed cheaply (send, archive, move, apply)
  • The action is frequent — frequency is exactly where confirm fatigue breeds
  • The cost of a five-second hold is invisible to the user

Confirm — reserve for when

  • Reversal is genuinely impossible (permanent deletion, sent money, published-to-world)
  • The consequence lands on someone else, who can't be un-notified
  • Law or safety demands an explicit second assent
HistoryUndo enters computing with Xerox PARC's editors (1970s); its modern rehabilitation as a *shipping* mercy is the Gmail send-undo era.
SpecimensGmail undo-send · toast-with-undo after archive · the delete-confirm that guards a trash folder (the anti-specimen: double protection of a reversible act).
Principle at stakeError tolerance & feedback — Stairwell. Confirm fatigue is a mode of basement failure.
SourcesNorman on error design; platform toast/snackbar primary docs; Nielsen on confirmation fatigue.

Why traditional: “Undo beats confirm wherever undo is possible” is this floor’s judgement and long practice, not a measured result.