Alignment stopped depending on the width tables being right about a glyph.
After anything whose drawn width is not certain, a row now carries an
absolute column address naming the column the app measured that glyph
into, so a mismeasured emoji costs one cell inside its own lane instead
of every lane after it and the frame's right border.
The curated narrow/wide sets keep their job — they are what makes the
reservation right, so a listed glyph gets neither a gap nor an overwrite
— but they are no longer what holds a row together. A name off the air,
which nobody can put on a list in advance, now frames flush too.
Pinning only where it is needed: the ranges the app draws in bulk and both
authorities agree are one cell (box drawing, braille, blocks, the node
marks, the chevrons) are listed, and a row holding nothing else is handed
back untouched — one scan, no walk. That list is a performance claim, not
what correctness rests on; getting an entry wrong costs what today costs.
Proved against a terminal that disagrees on purpose rather than against a
measurement, since the disagreement is the thing that cannot be probed.
Still limited to the rows the fast renderer writes itself: a frame
prompt_toolkit lays out — a dialog, and the backdrop it repaints — tracks
the cursor in its own arithmetic and is uncorrected. MESHTERM_COLUMN_SNAP=0
turns it off.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Jean-Pierre MartineauandClaude Opus 5
03befa76ac