line_hl_group bg occupies a separate rendering channel from hl_group in
Neovim's extmark system, causing character-level bg-only highlights to be
invisible regardless of priority. Switching to hl_group + hl_eol ensures
all backgrounds compete in the same channel.
Also reorders priorities (Normal 198 < line bg 199 < syntax 200 < char
bg 201), bumps char-level blend alpha from 0.4 to 0.7 for visibility,
and adds debug logging throughout the intra pipeline.
Line-level backgrounds (DiffsAdd/DiffsDelete) now get a second tier:
changed characters within modified lines receive an intense background
overlay (DiffsAddText/DiffsDeleteText at 70% alpha vs 40% for lines).
Treesitter foreground colors show through since the extmarks only set bg.
diff.lua extracts contiguous -/+ change groups from hunk lines and diffs
each group byte-by-byte using vim.diff(). An optional libvscodediff FFI
backend (lib.lua) auto-downloads the .so from codediff.nvim releases and
falls back to native if unavailable.
New config: highlights.intra.{enabled, algorithm, max_lines}. Gated by
max_lines (default 200) to avoid stalling on huge hunks. Priority 201
sits above treesitter (200) so the character bg always wins.
Closes#60
Compares current buffer against any git revision (default HEAD), opens result
with full diffs.nvim syntax highlighting. Follows fugitive convention:
:Gdiff/:Gvdiff open vertical split, :Ghdiff opens horizontal split.
Apply treesitter highlighting to diff metadata lines (diff --git, index,
---, +++) using the diff language parser. Header info is attached only
to the first hunk of each file to avoid duplicate highlighting.
Based on PR #52 by @phanen with fixes:
- header_lines now only contains diff metadata, not hunk content
- header info attached only to first hunk per file
- removed arbitrary hunk count restriction
