Replace the physical ekp-region renderer with ekp-buffer text-property projection backed by shared semantic layout plans and stable live-edit transactions.
Optimize the C-backed resize hot path, and add deterministic performance, ERT, GUI, fuzz, release, and documentation coverage for task017 through task032.
BREAKING CHANGE: require ekp-buffer instead of ekp-region and rename module-owned ekp-region-* settings to ekp-buffer-*.
Complete task002 through task016 across cache correctness, editor lifecycle, C boundaries, build and release governance, dictionary provenance, performance, interactive workflows, tests, documentation, and final cleanup.
Two root causes made justified text overrun the window's right edge
in real user sessions (every line ending in the "$" truncation
marker), while emacs -Q looked fine:
1. Windows WITHOUT fringes draw the truncation/continuation
indicator in the text area's LAST COLUMN, so the usable width is
one character less than window-body-width. ekp reserved only a
2px margin: with fringes disabled (a common minimal setup, and
all ttys) every line that hit the target width exactly had its
final glyph displaced by the "$". ekp-region--window-pixel now
reserves one frame-char-width when the window has no right
fringe. (The same lesson ebox-playground encodes in its
viewport-width reserve.)
2. Measurement was blind to the buffer's display context:
string-pixel-width works in a bare hidden buffer, ignoring
face-remapping-alist — which is where text-scale-mode, themes
and per-buffer font tweaks live. Under a remap, the DP laid
lines out with one font's metrics and the display rendered them
with another's: scale +3 made 5 of 7 sample lines overflow a
1330px window by up to 900px (GUI-measured). Measurement now
runs with the destination buffer's face-remapping-alist (the
29/30-compatible equivalent of Emacs 31's string-pixel-width
BUFFER argument), and the width/paragraph caches key on that
context so buffers at different scales never alias. text-scale
changes also trigger a re-flow in ekp-auto-justify-mode.
Ground truth, measured with window-text-pixel-size in GUI Emacs
across 7 display contexts (plain / text-scale ±| face remap /
no-fringes / no-fringes+scale / narrow+scale): the widest justified
line equals the target width exactly in every case, zero lines
overflow. Verbatim code blocks are exempt by design (they never
reflow, like any code line in a narrow window).
New tooling so this never regresses invisibly:
- M-x ekp-diagnose: renders a probe line in YOUR buffer and reports
target vs rendered width — run it in any session where justified
text looks wrong.
- tests/ekp-gui-verify.el: M-x ekp-gui-verify (single check in a
customized session) and ekp-gui-verify-matrix (the 7-case table,
for emacs -Q).
- 2 new batch ERT tests pin the context-keyed caches (94 total).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
