Locking should be free. Unlocking should cost you.

Open any focus app and you will find a switch. Flip it on, the apps go away. Flip it off, they come back. The two directions cost exactly the same: one tap each. That symmetry feels fair, and it is the reason almost none of them work.

You are not the same person all day

The person who sets up a blocker is rested, motivated, and thinking about next week. The person who disables it is tired, bored, and thinking about the next ninety seconds. They share a phone and a name, and almost nothing else. A symmetric switch hands the second person the exact same power as the first, at the precise moment they are least equipped to use it well.

Any lock you can undo from the couch, you will undo from the couch.

Make the two directions different

Spark deliberately breaks the symmetry. Locking is instant and completely free: one tap, no key, no Bluetooth, no network, no waiting. We never want friction between you and the decision to focus. If locking were annoying you would simply stop doing it.

Unlocking is the only gated direction. Your phone has to prove the physical key is nearby before it will give the apps back. Leave the key in a drawer in another room and the cost of caving is no longer a tap — it is standing up. That is the whole trick: a willpower problem becomes a walking problem, and walking problems are far easier to lose interest in halfway through.

• Lock: instant, keyless, works with Bluetooth off and no signal.
• Unlock: requires the key physically present, verified cryptographically.
• Both directions are honest about what they can and cannot enforce.

Why not just a timer?

Timers fail in the other direction: they are impossible to undo even when you genuinely need to. A parent needs their phone in an emergency. A timer that cannot be broken is a liability, and one that can be broken with a tap is decoration. A physical key sits in between — a real cost, always payable, never free.

That is the entire product thesis. Everything else is implementation.