Text measurement and fitting

text.ts replaced ceil(len / 18) * size, which overflowed the artboard on long hooks. Canvas measureText was rejected deliberately: "a layout that differs between test and production is worse than one that is slightly conservative in both."

Advance table (em)

FAMILY_SCALE = { sans: 1, display: 1, serif: 0.97, mono: 1.15 }, MONO_ADVANCE = 0.6, SAFETY = 1.02 — a deliberate 2% over-estimate, because predicting one line too many costs a slightly smaller font and predicting one too few puts text off the slide.

Wrapping

Greedy, with pre-wrap semantics. Split on \n (hard breaks), then on /(\s+)/ keeping whitespace runs as tokens. If a word does not fit, flush the line; if the token was whitespace, drop it (browsers drop leading whitespace on a wrapped line); an over-wide single word is broken mid-word by scanning for the longest prefix that fits.

lineCount is Math.max(1, lines) — never zero.

Fitting

fitToBox sorts the ladder descending regardless of input order and returns the first size where lines × fontSize × lineHeight <= maxHeight. If none fit it returns the smallest with overflows: true and its real height. It never clamps; callers must.

ladder(max, min, steps = 12) produces evenly spaced integers, deduped. ladder(104, 40) → 104, 98, 92, 87, 81, 75, 69, 63, 57, 52, 46, 40.

clampY pins an oversized block to the top of its region rather than centring it, so the start stays readable.