Your streak goes up by one on each day you meet the daily goal, and only once per day however much you study. If you miss days, freezes cover them at a rate of one freeze per missed day — but you need enough to cover every missed day at once. Two days missed with one freeze in hand does not buy you a partial reprieve; the streak resets to 1 and the freeze stays unspent.
What counts as a day
Meeting the daily goal. Opening the app does not do it, and neither does a session you abandon before the goal is reached. Once the goal is met the streak advances, and further sessions that day change nothing about it — the same day cannot be counted twice.
This is worth knowing if you like to bank effort. Doing five sessions on Sunday does not carry you through Monday. Streaks measure consecutive days, not total work, which is the only thing that makes them a useful signal about a habit.
How freezes are spent
Suppose your last active day was Monday and you come back on Thursday. That is two missed days, Tuesday and Wednesday. If you hold two or more freezes, two are deducted and the streak continues upward as though you had not missed anything. If you hold one, or none, the streak resets to 1.
The all-or-nothing part surprises people. A single freeze does not shorten a two-day gap into a one-day gap. It either covers the whole absence or it is not spent at all, and when it is not spent you keep it for next time.
Reset means 1, not 0
When a streak breaks, it resets to 1 rather than to zero, because the day you came back is itself a day you met the goal. You are not starting from nothing; you are starting from today, which you have already done.
Your longest streak is kept separately and is never reduced. Breaking a run of forty days does not erase the forty.
What a streak is actually for
It is a consistency signal, not a knowledge one. It says nothing about whether the words stuck — mastery does that. A hundred-day streak of the lightest possible sessions is a hundred days of showing up, which is genuinely worth something, and is not the same as a hundred days of learning.
The review schedule assumes roughly daily contact, so keeping a streak and keeping the schedule fed happen to be the same action. That is the useful part of the mechanic, rather than the number itself.