feat: fix highlighting

doc/fugitive-ts.nvim.txt

@@ -66,9 +66,11 @@ CONFIGURATION                                               *fugitive-ts-config*
                              this many lines. Prevents lag on massive diffs.
 
         {conceal_prefixes}   (boolean, default: true)
-                             Hide diff prefixes (`+`/`-`/` `) using extmark
-                             conceal. Makes code appear without the leading
-                             diff character.
+                             Hide diff prefixes (`+`/`-`/` `) using virtual
+                             text overlay. Makes code appear without the
+                             leading diff character. When `highlights.background`
+                             is also enabled, the overlay inherits the line's
+                             background color.
 
         {highlights}         (table, default: see below)
                              Controls which highlight features are enabled.
@@ -79,23 +81,22 @@ CONFIGURATION                                               *fugitive-ts-config*
         {treesitter}         (boolean, default: true)
                              Apply treesitter syntax highlighting to code.
 
-        {headers}            (boolean, default: true)
-                             Highlight function context in hunk headers.
-                             The context portion of `@@ -10,3 +10,4 @@ func()`
-                             will receive treesitter highlighting.
-
         {background}         (boolean, default: true)
-                             Apply `DiffAdd` background to `+` lines and
-                             `DiffDelete` background to `-` lines.
+                             Apply background highlighting to `+`/`-` lines
+                             using `FugitiveTsAdd`/`FugitiveTsDelete` groups
+                             (derived from `DiffAdd`/`DiffDelete` backgrounds).
 
         {linenr}             (boolean, default: true)
-                             Highlight line numbers with `DiffAdd`/`DiffDelete`
-                             colors matching the line background.
+                             Highlight line numbers with matching colors.
+                             Only visible if line numbers are enabled.
 
         {vim}                (boolean, default: false)
                              Experimental: Use vim syntax highlighting as
                              fallback when no treesitter parser is available.
 
+    Note: Header context (e.g., `@@ -10,3 +10,4 @@ func()`) is always
+    highlighted with treesitter when a parser is available.
+
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 API                                                            *fugitive-ts-api*
 
@@ -129,10 +130,10 @@ IMPLEMENTATION                                    *fugitive-ts-implementation*
    - Language is detected from the filename using |vim.filetype.match()|
    - Diff prefixes (`+`/`-`/` `) are stripped from code lines
    - Code is parsed with |vim.treesitter.get_string_parser()|
-   - Background extmarks (`DiffAdd`/`DiffDelete`) applied at priority 198
+   - Background extmarks (`FugitiveTsAdd`/`FugitiveTsDelete`) at priority 198
    - `Normal` extmarks at priority 199 clear underlying diff foreground
    - Treesitter highlights are applied as extmarks at priority 200
-   - Conceal extmarks hide diff prefixes when `conceal_prefixes` is enabled
+   - Virtual text overlays hide diff prefixes when `conceal_prefixes` is enabled
 4. Re-highlighting occurs on `TextChanged` (debounced) and `Syntax` events
 
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