For people who ship things with a model in the loop
Getting a thing working is the part AI made easy. The part it did not make easy is the second tap that charges twice, the fallback that reports green, the state with two owners, the bug you cannot reproduce. Nobody wrote you a tutorial for those because they are not features. They are the calls.
No account, no card, and nothing to install. The activity runs in the tab you already have open.
Tuesday. The idempotency key on the payment write is built from user plus cart contents and lasts 15 minutes. Mr. Okafor ordered the same kettle twice in one minute, one for each daughter, and the second order was silently dropped. Support asks you to shorten the window to 30 seconds. What do you do?
Nothing is sent and nothing is stored. Pick one.
The builder card deck works four skills, and the difficulty steps up on a skill you have already answered cleanly rather than on a clock. The public activity draws from the same direction.
A repo shows what you built. It does not show that you knew the second tap was going to charge twice. A finished card holds the situation, the call you made, what changed after feedback, and an honest note on where AI helped, which is the part most portfolios quietly leave out.
Seal one thing you shippedNot for these cards. The builder pack asks you to read a situation and make a call, in plain words. Datum also has runnable coding exercises inside a workspace, but nothing here requires you to open an editor.
An assistant answers. These cards make you answer first, then show you the consequence of the branch you chose. The skill being built is the judgment before the prompt, not the prompt.
The daily activity, one question to Datumly and the proof flow need no account. On an account, Practice, Datumly and voice are free. The paid tier is a larger monthly allowance of AI runs, nothing else.
Yes. Cards carry a difficulty, and the deck reaches for a higher step on a skill you have answered cleanly. Resting never sends you backwards.
Your draft stays in the tab. If you ask for AI help, the activity and a short copy of your draft are sent once, and Datum does not save that request. Vault files are encrypted on your device before they leave it.
Yes, and only you can see it. Missing a day costs nothing you made. A private streak only you can see, with freezes, and nothing sent about it. No public leaderboard of people.
One situation, three answers, and what happened next. Ten minutes, no account.