What is Mastery?

In Kumi, mastery is how well you know a single concept, scored from 0 to 100. It is not one flat number pulled from thin air. It is built from every way you can actually know that concept, and it moves only as you show you know them.

Mastery is measured per concept. Each word, kanji, radical, and grammar point has its own mastery score, and those scores are what your KMT in each domain is built from.

You might recognize a word on sight but blank when you try to say it yourself. That's why Kumi tracks reading, producing, listening, and writing separately, then combines them into the concept's overall mastery.

This is why Kumi can tell the difference between a word you vaguely recognize and one you can actually use. A plain flashcard app collapses all of that into one pass-or-fail. Kumi keeps them distinct, so your score reflects how you know something, not just whether you have seen it.

Every review feeds mastery with more than whether you got it right. Kumi also weighs how quickly you answered and whether the review was on schedule. A fast, genuine recall on a review that was actually due counts fully. Answering slowly, or cramming the same card over and over off schedule, barely moves the needle.

It also builds confidence over time. One right answer doesn't prove much. A track record of well-timed reviews does. So your mastery reflects not just that you were right once, but that you can be right reliably.

Under the hood, the number you see is two dials multiplied: strength and freshness. Strength is your proven ability: it grows when you answer a due review correctly, and a wrong answer never raises it. Freshness is how recently you proved it: it drains as time passes and refills the moment you review.

This explains something that surprises people: miss a card you have not seen in months and its displayed mastery can still go up. Your strength took the hit it deserved, but the review refreshed a very stale memory, and the freshness recovery outweighed the strength drop. The number is not being generous. It is being precise about two different things at once.

Because each way of knowing a concept is measured separately, you cannot reach full mastery by drilling one easy angle. To max out a concept, you have to show you know it several ways. Marking something known or importing it from Anki gives you a head start, but it is a starting guess with no track record behind it, and your real reviews quickly confirm or correct it.

As a concept's score climbs, it passes through five stages:

• Novice. Just introduced. Expect misses.
• Developing. Starting to stick, with real gaps.
• Proficient. Most reviews land, but it isn't solid yet.
• Expert. Strong and reliable across most ways of knowing it.
• Master. Deep, well-rounded command of the concept.

The top of the mountain has a name. A concept earns MASTERED only when all of the following are true, and every one of them comes from real answers, never from imports or self-reports:

• Proven both ways. You have answered it correctly in recognition (you saw it and knew it) and in production (you supplied it yourself).
• It survived time. Both sides held through a gap of at least three months. Not three months of drilling: three months of the memory lasting.
• The whole concept is strong. Its overall score sits at 88 or above, with every module you practice holding firm, not one strong angle carrying weak ones.
• Both sides are enabled. If you trimmed your lattice down to recognition only, that concept cannot be mastered at all. Kumi never hands out the badge for half the skill.

Your first crossing gets a full-screen moment, and mastered concepts feed a dedicated leaderboard: a full-lattice concept is worth a whole point, a trimmed lattice is worth the fraction you kept. Expect the climb to take months, not weeks. Our simulations predict roughly six to eight months for knowledge you seeded and four and a half to seven and a half for concepts learned from scratch. That is the point: this badge is scarce because the thing it certifies is rare.

Mastery reflects what you know now, so it fades if you stop reviewing, the way real memory does. The longer a concept goes untouched, the more its score drifts down, and a well-timed review brings it back up. The more history a concept has, the more slowly it fades, because Kumi trusts a long track record more than a single lucky answer. This is the whole point of reviews: they keep your mastery honest.

Your KMT in a domain is built from the concepts you have mastered in it. Each tier holds a set of concepts; as you learn and hold on to them, you clear the tier and unlock the next. Mastery is the close-up, per-concept view, and KMT is the per-domain view of the same progress.