The stage is read straight from the scheduler's memory strength, so it moves when you learn. Colour ripens from sun to lime to leaf to ink, and the four pips say the same thing for anyone who can't tell the colours apart. On Read, the support a word gets recedes as it ripens.
Saved today. Not reviewed yet.
On ReadRecognize: the word in a sentence, recall the meaning.
PillNewIn review, holding for under a week. Comes back often.
On ReadRecognize early, then Cloze: a gap, the meaning as a hint.
PillLearningHolding for one week to two months. Comes back now and then and asks more.
On ReadListen, or Produce: see the meaning, say the word.
PillStrongHolding for two months or more. Leaves daily review. A spot check comes when it starts to fade.
On ReadA spot check, any format, months apart.
PillKnownYou said I know this. Out of review, not counted as Known. One tap in Words brings it back.
On ReadNone.
PillSkippedThresholds live in one constants object (7 and 60 days of stability). Tapping can't make a word Known; only reviews over time can. A missed spot check sends a Known word back to Learning with no message, and the Known count shows today's truth.
Milestones count Learned, so they are never taken back.