Problem: treesitter parses each diff hunk in isolation, so incomplete
syntax constructs at hunk boundaries (e.g., a function definition with
no body) produce ERROR nodes and drop captures.
Solution: read N lines from the on-disk file before/after each hunk and
prepend/append them as unmapped padding lines. The line_map guard in
highlight_treesitter skips extmarks for unmapped lines, so padding
provides syntax context without visual output. Controlled by
highlights.context (default 25, 0 to disable). Also applies to the vim
syntax fallback path via a leading_offset filter.
Problem: highlight_treesitter concatenated all hunk lines (context, -,
+) into a single string. Mixed old/new code produced invalid syntax
(e.g. two return statements), causing treesitter error recovery to drop
captures on lines after the syntax error.
Solution: split hunk lines into two versions — new (context + added)
and old (context + deleted) — each parsed independently. Use a line_map
to resolve treesitter row indices to buffer lines, with the old version
only mapping deleted lines to avoid duplicate extmarks on context.
Also fixes three related issues exposed by the improved TS coverage:
- Replace Normal extmark with DiffsClear (explicit fg from Normal.fg).
Normal in extmarks doesn't reliably override vim :syntax foreground.
- Reorder priority stack to DiffsClear(198) < syntax(199) < line
bg(200) < char bg(201). TS capture groups can carry colorscheme
backgrounds that would override diff line backgrounds at higher
priority.
- Gate DiffsClear on per-line coverage tracking. Only clear fugitive
syntax fg on lines where TS/vim actually produced captures, preventing
force-clearing on lines where error recovery drops captures.
'default' inherits algorithm and linematch from diffopt, 'vscode' uses
the FFI library. Removes the need for diffs.nvim to duplicate settings
that users already control globally.
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.
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
