Mirror the TUI line-number gutter in the pmacs-gpu frontend — the GPU half
of sub-arc 1. Frontend-local, no protocol change (Q#UX1); off by default,
enabled with `--line-numbers`.
The gutter is a reserved left strip mirroring the minimap's reserved right
column. All horizontal text geometry hangs off `TEXT_LEFT`; the gutter adds
`gutter_width_px()` to it via `text_left()`, applied at every byte→pixel x
site (main TextArea, caret, washes/squiggles) and subtracted at the one
pixel→byte site (mouse hit-test). The main text clip-left moves off 0.
- gutter_width_px = digits(line_count) * mono_advance + gap (px), advance
read from the shaped code buffer.
- A dedicated gutter_text_renderer + gutter_buffer draw right-aligned dim
numbers, reshaped per scroll (refresh_gutter_buffer), same font size +
line height as the code so rows align one-for-one.
- --line-numbers flag filtered out before the mode parser (position-
independent), threaded App → State.
Headless render test asserts enabling the gutter changes the frame (ink +
shift). fmt + clippy clean; 53 pmacs-gpu tests pass (render tests on the
local adapter). Needs a human eyeball before the PR.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014TXbAwk27agwhrNNrhLi2U
Levi Neuwirth
f7583e7994