The reflow caret layout hardcoded x0 = columnLeft. That matched only left-aligned
lines; for the new center/right headings the line renders at a shifted x (e.g. a
centered title starts ~215pt while columnLeft is the page margin ~54pt), so the
frontend mapped clicks and drew the caret ~160pt off the actual glyphs.
Record the line's true starting x (after lineX/center/right) as x0 instead. x0 is
caret-only metadata read by the live editor — it does not affect glyph emission or
the rendered page, so output is unchanged (overlay-diff gate identical: 1.70%/1.69%,
STRESS PASS). Rebuilt .pyd + WASM; cache version bumped.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
