User report: extending a highlight doubled letters into the recomputed
selection text ("aauuthenticcity off ... ruunss iinnto"). The exact-
position dedupe key (toFixed(3)) only collapsed duplicate glyphs whose
re-render copies landed inside the same rounding bucket — pdf.js
re-render copies can sit SUB-PIXEL SHIFTED, so per character the jitter
sometimes straddled a boundary and both copies survived, partially.
Dedupe by overlap instead: a glyph is a duplicate when a kept glyph on
the same line (y0 within half a glyph height) overlaps more than half
the narrower glyph's width. Distinct glyphs — including tight pairs —
never reach that; shifted duplicate copies always do. The snap tables
share the source, so their boundary lists are clean too.
The root cause remains the fork's pdf.js render() appending a fresh
span set without clearing .textLayer (open bug, fork-cycle fix); this
is the defensive layer that makes the adjust feature correct regardless.
Repaired the affected highlight's stored text with the fixed recompute
(verified: the same live duplicated DOM now yields the exact line text
with zero doubling).
John O'Keefe
dbeefb395c