Carry the line-number mode to the GPU so it renders relative/hybrid, not
just on/off. The v13 wire carried `LineNumbers { enabled: bool }`
(off/absolute only); v14 carries the full mode.
- Protocol: `LineNumberMode {Off, Absolute, Relative, Hybrid}` moves into
pmacs-protocol (with `number_for`/`is_on`) so the wire, daemon, and both
frontends share ONE enum and ONE number rule (Q#UX7); `pmacs` re-exports
it as `crate:🪟:LineNumberMode`. `LineNumbers.enabled: bool` →
`mode: LineNumberMode`. PROTOCOL_VERSION 13 → 14, SUPPORTED → [6..14],
daemon-gated `< 14` (a v13 peer gets no LineNumbers, like the v10
SearchPrompt bump).
- Producer (`line_numbers_msg`): ships the window's mode (cached-suppress
on the mode now, seeded to Off).
- GPU: `line_numbers` field becomes the mode; `refresh_gutter_buffer`
computes each number via `mode.number_for(line, cursor_line)` against the
GPU's own cursor line (`cursor_line()` off `current_line_starts`). The
buffer rebuilds every render, so relative numbers track the cursor for
free. Gutter width unchanged (sized by line count → stable).
Tests: GPU headless render proves relative ≠ absolute with the cursor on
line 2; producer test asserts the mode ships; protocol version pins → 14.
fmt + clippy --all-targets clean both flavors + gpu; 1446 lib + 12 protocol
+ 55 pmacs-gpu tests pass. Needs a GPU eyeball.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014TXbAwk27agwhrNNrhLi2U
Levi Neuwirth
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