Learning a spell by tracing a glyph

Find a fragment: in a ruin, on a shard, as a gift or a quest reward.
Trace it with both thumbs, slowly if needed; no breath limit. A trace counts when it is recognised and clears the learning bar. When enough traces count, the spell is learned. (This is what the learning code already does.)
Glyphs come in several kinds:
- Whole: one fragment holds the whole spell, since the other hand's stroke follows from it. Most mirrored and parallel spells.
- Split: each half of an asymmetric glyph sits on a different fragment, often far apart, and you need both. Facet Seal works this way: the circle is given in Lanternfall, the square is found in the Shardfield.
- Taught: no fragment exists; a teacher traces it with you, hand over hand, so the teacher decides who learns. Faction secrets and Facet gifts.
- Reflected: visible only in one reflection, such as a pool at dawn or a shard during a glass storm. You trace it while it shows.
- Warp-born: surfaces at a fresh warp and fades within days. The in-world form of time-limited content drops.
(Idea) The first fragment is Coil, at the Drowned Steps at the end of the Prologue, with Aske teaching the method.