Merge pull request #21 from barrettruth/feat/highlighting

highlighting

doc/fugitive-ts.nvim.txt

@@ -56,11 +56,6 @@ CONFIGURATION                                               *fugitive-ts-config*
                              Example: >lua
                                  disabled_languages = { 'markdown', 'text' }
 <
-        {highlight_headers}  (boolean, default: true)
-                             Highlight function context in hunk headers.
-                             The context portion of `@@ -10,3 +10,4 @@ func()`
-                             will receive treesitter highlighting.
-
         {debounce_ms}        (integer, default: 50)
                              Debounce delay in milliseconds for re-highlighting
                              after buffer changes. Lower values feel snappier
@@ -70,6 +65,38 @@ CONFIGURATION                                               *fugitive-ts-config*
                              Skip treesitter highlighting for hunks larger than
                              this many lines. Prevents lag on massive diffs.
 
+        {conceal_prefixes}   (boolean, default: true)
+                             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.
+                             See |fugitive-ts.Highlights| for fields.
+
+                                                       *fugitive-ts.Highlights*
+    Highlights table fields: ~
+        {treesitter}         (boolean, default: true)
+                             Apply treesitter syntax highlighting to code.
+
+        {background}         (boolean, default: true)
+                             Apply background highlighting to `+`/`-` lines
+                             using `FugitiveTsAdd`/`FugitiveTsDelete` groups
+                             (derived from `DiffAdd`/`DiffDelete` backgrounds).
+
+        {linenr}             (boolean, default: true)
+                             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.
+
 ==============================================================================
 API                                                            *fugitive-ts-api*
 
@@ -103,8 +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 (`FugitiveTsAdd`/`FugitiveTsDelete`) at priority 198
+   - `Normal` extmarks at priority 199 clear underlying diff foreground
    - Treesitter highlights are applied as extmarks at priority 200
-   - A `Normal` extmark at priority 199 clears underlying diff colors
+   - Virtual text overlays hide diff prefixes when `conceal_prefixes` is enabled
 4. Re-highlighting occurs on `TextChanged` (debounced) and `Syntax` events
 
 ==============================================================================

lua/fugitive-ts/highlight.lua

@@ -1,8 +1,18 @@
 local M = {}
 
+local debug_enabled = false
+
+---@param enabled boolean
+function M.set_debug(enabled)
+  debug_enabled = enabled
+end
+
 ---@param msg string
 ---@param ... any
 local function dbg(msg, ...)
+  if not debug_enabled then
+    return
+  end
   local formatted = string.format(msg, ...)
   vim.notify('[fugitive-ts] ' .. formatted, vim.log.levels.DEBUG)
 end
@@ -13,9 +23,8 @@ end
 ---@param col_offset integer
 ---@param text string
 ---@param lang string
----@param debug? boolean
 ---@return integer
-local function highlight_text(bufnr, ns, hunk, col_offset, text, lang, debug)
+local function highlight_text(bufnr, ns, hunk, col_offset, text, lang)
   local ok, parser_obj = pcall(vim.treesitter.get_string_parser, text, lang)
   if not ok or not parser_obj then
     return 0
@@ -55,28 +64,29 @@ local function highlight_text(bufnr, ns, hunk, col_offset, text, lang, debug)
   return extmark_count
 end
 
+---@class fugitive-ts.HunkOpts
+---@field max_lines integer
+---@field conceal_prefixes boolean
+---@field highlights fugitive-ts.Highlights
+
 ---@param bufnr integer
 ---@param ns integer
 ---@param hunk fugitive-ts.Hunk
----@param max_lines integer
+---@param opts fugitive-ts.HunkOpts
----@param highlight_headers boolean
+function M.highlight_hunk(bufnr, ns, hunk, opts)
----@param debug? boolean
-function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
   local lang = hunk.lang
   if not lang then
     return
   end
 
-  if #hunk.lines > max_lines then
+  if #hunk.lines > opts.max_lines then
-    if debug then
+    dbg(
-      dbg(
+      'skipping hunk %s:%d (%d lines > %d max)',
-        'skipping hunk %s:%d (%d lines > %d max)',
+      hunk.filename,
-        hunk.filename,
+      hunk.start_line,
-        hunk.start_line,
+      #hunk.lines,
-        #hunk.lines,
+      opts.max_lines
-        max_lines
+    )
-      )
-    end
     return
   end
 
@@ -93,29 +103,23 @@ function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
 
   local ok, parser_obj = pcall(vim.treesitter.get_string_parser, code, lang)
   if not ok or not parser_obj then
-    if debug then
+    dbg('failed to create parser for lang: %s', lang)
-      dbg('failed to create parser for lang: %s', lang)
-    end
     return
   end
 
   local trees = parser_obj:parse()
   if not trees or #trees == 0 then
-    if debug then
+    dbg('parse returned no trees for lang: %s', lang)
-      dbg('parse returned no trees for lang: %s', lang)
-    end
     return
   end
 
   local query = vim.treesitter.query.get(lang, 'highlights')
   if not query then
-    if debug then
+    dbg('no highlights query for lang: %s', lang)
-      dbg('no highlights query for lang: %s', lang)
-    end
     return
   end
 
-  if highlight_headers and hunk.header_context and hunk.header_context_col then
+  if hunk.header_context and hunk.header_context_col then
     local header_line = hunk.start_line - 1
     pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, header_line, hunk.header_context_col, {
       end_col = hunk.header_context_col + #hunk.header_context,
@@ -123,8 +127,8 @@ function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
       priority = 199,
     })
     local header_extmarks =
-      highlight_text(bufnr, ns, hunk, hunk.header_context_col, hunk.header_context, lang, debug)
+      highlight_text(bufnr, ns, hunk, hunk.header_context_col, hunk.header_context, lang)
-    if debug and header_extmarks > 0 then
+    if header_extmarks > 0 then
       dbg('header %s:%d applied %d extmarks', hunk.filename, hunk.start_line, header_extmarks)
     end
   end
@@ -132,7 +136,32 @@ function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
   for i, line in ipairs(hunk.lines) do
     local buf_line = hunk.start_line + i - 1
     local line_len = #line
-    if line_len > 1 then
+    local prefix = line:sub(1, 1)
+
+    local is_diff_line = prefix == '+' or prefix == '-'
+    local line_hl = is_diff_line and (prefix == '+' and 'FugitiveTsAdd' or 'FugitiveTsDelete')
+      or nil
+
+    if opts.conceal_prefixes then
+      local virt_hl = (opts.highlights.background and line_hl) or nil
+      pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, {
+        virt_text = { { ' ', virt_hl } },
+        virt_text_pos = 'overlay',
+      })
+    end
+
+    if opts.highlights.background and is_diff_line then
+      local extmark_opts = {
+        line_hl_group = line_hl,
+        priority = 198,
+      }
+      if opts.highlights.linenr then
+        extmark_opts.number_hl_group = line_hl
+      end
+      pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, extmark_opts)
+    end
+
+    if line_len > 1 and opts.highlights.treesitter then
       pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 1, {
         end_col = line_len,
         hl_group = 'Normal',
@@ -141,6 +170,10 @@ function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
     end
   end
 
+  if not opts.highlights.treesitter then
+    return
+  end
+
   local extmark_count = 0
   for id, node, _ in query:iter_captures(trees[1]:root(), code) do
     local capture_name = '@' .. query.captures[id]
@@ -160,9 +193,7 @@ function M.highlight_hunk(bufnr, ns, hunk, max_lines, highlight_headers, debug)
     extmark_count = extmark_count + 1
   end
 
-  if debug then
+  dbg('hunk %s:%d applied %d extmarks', hunk.filename, hunk.start_line, extmark_count)
-    dbg('hunk %s:%d applied %d extmarks', hunk.filename, hunk.start_line, extmark_count)
-  end
 end
 
 return M

lua/fugitive-ts/init.lua

@@ -1,11 +1,18 @@
+---@class fugitive-ts.Highlights
+---@field treesitter boolean
+---@field background boolean
+---@field linenr boolean
+---@field vim boolean
+
 ---@class fugitive-ts.Config
 ---@field enabled boolean
 ---@field debug boolean
 ---@field languages table<string, string>
 ---@field disabled_languages string[]
----@field highlight_headers boolean
 ---@field debounce_ms integer
 ---@field max_lines_per_hunk integer
+---@field conceal_prefixes boolean
+---@field highlights fugitive-ts.Highlights
 
 ---@class fugitive-ts
 ---@field attach fun(bufnr?: integer)
@@ -24,9 +31,15 @@ local default_config = {
   debug = false,
   languages = {},
   disabled_languages = {},
-  highlight_headers = true,
   debounce_ms = 50,
   max_lines_per_hunk = 500,
+  conceal_prefixes = true,
+  highlights = {
+    treesitter = true,
+    background = true,
+    linenr = true,
+    vim = false,
+  },
 }
 
 ---@type fugitive-ts.Config
@@ -57,18 +70,14 @@ local function highlight_buffer(bufnr)
 
   vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
 
-  local hunks =
+  local hunks = parser.parse_buffer(bufnr, config.languages, config.disabled_languages)
-    parser.parse_buffer(bufnr, config.languages, config.disabled_languages, config.debug)
   dbg('found %d hunks in buffer %d', #hunks, bufnr)
   for _, hunk in ipairs(hunks) do
-    highlight.highlight_hunk(
+    highlight.highlight_hunk(bufnr, ns, hunk, {
-      bufnr,
+      max_lines = config.max_lines_per_hunk,
-      ns,
+      conceal_prefixes = config.conceal_prefixes,
-      hunk,
+      highlights = config.highlights,
-      config.max_lines_per_hunk,
+    })
-      config.highlight_headers,
-      config.debug
-    )
   end
 end
 
@@ -92,9 +101,9 @@ local function create_debounced_highlight(bufnr)
       config.debounce_ms,
       0,
       vim.schedule_wrap(function()
-        t:close()
         if timer == t then
           timer = nil
+          t:close()
         end
         highlight_buffer(bufnr)
       end)
@@ -147,7 +156,35 @@ end
 ---@param opts? fugitive-ts.Config
 function M.setup(opts)
   opts = opts or {}
+
+  vim.validate({
+    enabled = { opts.enabled, 'boolean', true },
+    debug = { opts.debug, 'boolean', true },
+    languages = { opts.languages, 'table', true },
+    disabled_languages = { opts.disabled_languages, 'table', true },
+    debounce_ms = { opts.debounce_ms, 'number', true },
+    max_lines_per_hunk = { opts.max_lines_per_hunk, 'number', true },
+    conceal_prefixes = { opts.conceal_prefixes, 'boolean', true },
+    highlights = { opts.highlights, 'table', true },
+  })
+
+  if opts.highlights then
+    vim.validate({
+      ['highlights.treesitter'] = { opts.highlights.treesitter, 'boolean', true },
+      ['highlights.background'] = { opts.highlights.background, 'boolean', true },
+      ['highlights.linenr'] = { opts.highlights.linenr, 'boolean', true },
+      ['highlights.vim'] = { opts.highlights.vim, 'boolean', true },
+    })
+  end
+
   config = vim.tbl_deep_extend('force', default_config, opts)
+  parser.set_debug(config.debug)
+  highlight.set_debug(config.debug)
+
+  local diff_add = vim.api.nvim_get_hl(0, { name = 'DiffAdd' })
+  local diff_delete = vim.api.nvim_get_hl(0, { name = 'DiffDelete' })
+  vim.api.nvim_set_hl(0, 'FugitiveTsAdd', { bg = diff_add.bg })
+  vim.api.nvim_set_hl(0, 'FugitiveTsDelete', { bg = diff_delete.bg })
 end
 
 return M

lua/fugitive-ts/parser.lua

@@ -8,9 +8,19 @@
 
 local M = {}
 
+local debug_enabled = false
+
+---@param enabled boolean
+function M.set_debug(enabled)
+  debug_enabled = enabled
+end
+
 ---@param msg string
 ---@param ... any
 local function dbg(msg, ...)
+  if not debug_enabled then
+    return
+  end
   local formatted = string.format(msg, ...)
   vim.notify('[fugitive-ts] ' .. formatted, vim.log.levels.DEBUG)
 end
@@ -18,15 +28,12 @@ end
 ---@param filename string
 ---@param custom_langs? table<string, string>
 ---@param disabled_langs? string[]
----@param debug? boolean
 ---@return string?
-local function get_lang_from_filename(filename, custom_langs, disabled_langs, debug)
+local function get_lang_from_filename(filename, custom_langs, disabled_langs)
   if custom_langs and custom_langs[filename] then
     local lang = custom_langs[filename]
     if disabled_langs and vim.tbl_contains(disabled_langs, lang) then
-      if debug then
+      dbg('lang disabled: %s', lang)
-        dbg('lang disabled: %s', lang)
-      end
       return nil
     end
     return lang
@@ -34,28 +41,22 @@ local function get_lang_from_filename(filename, custom_langs, disabled_langs, de
 
   local ft = vim.filetype.match({ filename = filename })
   if not ft then
-    if debug then
+    dbg('no filetype for: %s', filename)
-      dbg('no filetype for: %s', filename)
-    end
     return nil
   end
 
   local lang = vim.treesitter.language.get_lang(ft)
   if lang then
     if disabled_langs and vim.tbl_contains(disabled_langs, lang) then
-      if debug then
+      dbg('lang disabled: %s', lang)
-        dbg('lang disabled: %s', lang)
-      end
       return nil
     end
     local ok = pcall(vim.treesitter.language.inspect, lang)
     if ok then
       return lang
     end
-    if debug then
+    dbg('no parser for lang: %s (ft: %s)', lang, ft)
-      dbg('no parser for lang: %s (ft: %s)', lang, ft)
+  else
-    end
-  elseif debug then
     dbg('no ts lang for filetype: %s', ft)
   end
 
@@ -65,9 +66,8 @@ end
 ---@param bufnr integer
 ---@param custom_langs? table<string, string>
 ---@param disabled_langs? string[]
----@param debug? boolean
 ---@return fugitive-ts.Hunk[]
-function M.parse_buffer(bufnr, custom_langs, disabled_langs, debug)
+function M.parse_buffer(bufnr, custom_langs, disabled_langs)
   local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
   ---@type fugitive-ts.Hunk[]
   local hunks = {}
@@ -107,8 +107,8 @@ function M.parse_buffer(bufnr, custom_langs, disabled_langs, debug)
     if filename then
       flush_hunk()
       current_filename = filename
-      current_lang = get_lang_from_filename(filename, custom_langs, disabled_langs, debug)
+      current_lang = get_lang_from_filename(filename, custom_langs, disabled_langs)
-      if debug and current_lang then
+      if current_lang then
         dbg('file: %s -> lang: %s', filename, current_lang)
       end
     elseif line:match('^@@.-@@') then

spec/highlight_spec.lua

@@ -7,6 +7,10 @@ describe('highlight', function()
 
     before_each(function()
       ns = vim.api.nvim_create_namespace('fugitive_ts_test')
+      local diff_add = vim.api.nvim_get_hl(0, { name = 'DiffAdd' })
+      local diff_delete = vim.api.nvim_get_hl(0, { name = 'DiffDelete' })
+      vim.api.nvim_set_hl(0, 'FugitiveTsAdd', { bg = diff_add.bg })
+      vim.api.nvim_set_hl(0, 'FugitiveTsDelete', { bg = diff_delete.bg })
     end)
 
     local function create_buffer(lines)
@@ -25,6 +29,31 @@ describe('highlight', function()
       return vim.api.nvim_buf_get_extmarks(bufnr, ns, 0, -1, { details = true })
     end
 
+    local function default_opts(overrides)
+      local opts = {
+        max_lines = 500,
+        conceal_prefixes = false,
+        highlights = {
+          treesitter = true,
+          background = false,
+          linenr = false,
+          vim = false,
+        },
+      }
+      if overrides then
+        for k, v in pairs(overrides) do
+          if k == 'highlights' then
+            for hk, hv in pairs(v) do
+              opts.highlights[hk] = hv
+            end
+          else
+            opts[k] = v
+          end
+        end
+      end
+      return opts
+    end
+
     it('applies extmarks for lua code', function()
       local bufnr = create_buffer({
         '@@ -1,1 +1,2 @@',
@@ -39,7 +68,7 @@ describe('highlight', function()
         lines = { ' local x = 1', '+local y = 2' },
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       assert.is_true(#extmarks > 0)
@@ -60,7 +89,7 @@ describe('highlight', function()
         lines = { ' local x = 1', '+local y = 2' },
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       local has_normal = false
@@ -90,7 +119,7 @@ describe('highlight', function()
         lines = hunk_lines,
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       assert.are.equal(0, #extmarks)
@@ -111,7 +140,7 @@ describe('highlight', function()
         lines = { ' some content', '+more content' },
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       assert.are.equal(0, #extmarks)
@@ -134,7 +163,7 @@ describe('highlight', function()
         lines = { ' local x = 1', '+local y = 2' },
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, true, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       local has_header_extmark = false
@@ -148,9 +177,9 @@ describe('highlight', function()
       delete_buffer(bufnr)
     end)
 
-    it('does not highlight header when disabled', function()
+    it('does not highlight header when no header_context', function()
       local bufnr = create_buffer({
-        '@@ -10,3 +10,4 @@ function hello()',
+        '@@ -10,3 +10,4 @@',
         ' local x = 1',
       })
 
@@ -158,12 +187,10 @@ describe('highlight', function()
         filename = 'test.lua',
         lang = 'lua',
         start_line = 1,
-        header_context = 'function hello()',
-        header_context_col = 18,
         lines = { ' local x = 1' },
       }
 
-      highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
 
       local extmarks = get_extmarks(bufnr)
       local header_extmarks = 0
@@ -189,7 +216,7 @@ describe('highlight', function()
       }
 
       assert.has_no.errors(function()
-        highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+        highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
       end)
       delete_buffer(bufnr)
     end)
@@ -209,9 +236,294 @@ describe('highlight', function()
       }
 
       assert.has_no.errors(function()
-        highlight.highlight_hunk(bufnr, ns, hunk, 500, false, false)
+        highlight.highlight_hunk(bufnr, ns, hunk, default_opts())
       end)
       delete_buffer(bufnr)
     end)
+
+    it('applies overlay extmarks when conceal_prefixes enabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts({ conceal_prefixes = true }))
+
+      local extmarks = get_extmarks(bufnr)
+      local overlay_count = 0
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text_pos == 'overlay' then
+          overlay_count = overlay_count + 1
+        end
+      end
+      assert.are.equal(2, overlay_count)
+      delete_buffer(bufnr)
+    end)
+
+    it('does not apply overlay extmarks when conceal_prefixes disabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(bufnr, ns, hunk, default_opts({ conceal_prefixes = false }))
+
+      local extmarks = get_extmarks(bufnr)
+      local overlay_count = 0
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text_pos == 'overlay' then
+          overlay_count = overlay_count + 1
+        end
+      end
+      assert.are.equal(0, overlay_count)
+      delete_buffer(bufnr)
+    end)
+
+    it('applies DiffAdd background to + lines when background enabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { background = true } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_diff_add = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].line_hl_group == 'FugitiveTsAdd' then
+          has_diff_add = true
+          break
+        end
+      end
+      assert.is_true(has_diff_add)
+      delete_buffer(bufnr)
+    end)
+
+    it('applies DiffDelete background to - lines when background enabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,2 +1,1 @@',
+        ' local x = 1',
+        '-local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '-local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { background = true } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_diff_delete = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].line_hl_group == 'FugitiveTsDelete' then
+          has_diff_delete = true
+          break
+        end
+      end
+      assert.is_true(has_diff_delete)
+      delete_buffer(bufnr)
+    end)
+
+    it('does not apply background when background disabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { background = false } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_line_hl = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].line_hl_group then
+          has_line_hl = true
+          break
+        end
+      end
+      assert.is_false(has_line_hl)
+      delete_buffer(bufnr)
+    end)
+
+    it('applies number_hl_group when linenr enabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { background = true, linenr = true } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_number_hl = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].number_hl_group then
+          has_number_hl = true
+          break
+        end
+      end
+      assert.is_true(has_number_hl)
+      delete_buffer(bufnr)
+    end)
+
+    it('does not apply number_hl_group when linenr disabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { background = true, linenr = false } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_number_hl = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].number_hl_group then
+          has_number_hl = true
+          break
+        end
+      end
+      assert.is_false(has_number_hl)
+      delete_buffer(bufnr)
+    end)
+
+    it('skips treesitter highlights when treesitter disabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { treesitter = false, background = true } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_ts_highlight = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].hl_group and mark[4].hl_group:match('^@') then
+          has_ts_highlight = true
+          break
+        end
+      end
+      assert.is_false(has_ts_highlight)
+      delete_buffer(bufnr)
+    end)
+
+    it('still applies background when treesitter disabled', function()
+      local bufnr = create_buffer({
+        '@@ -1,1 +1,2 @@',
+        ' local x = 1',
+        '+local y = 2',
+      })
+
+      local hunk = {
+        filename = 'test.lua',
+        lang = 'lua',
+        start_line = 1,
+        lines = { ' local x = 1', '+local y = 2' },
+      }
+
+      highlight.highlight_hunk(
+        bufnr,
+        ns,
+        hunk,
+        default_opts({ highlights = { treesitter = false, background = true } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local has_diff_add = false
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].line_hl_group == 'FugitiveTsAdd' then
+          has_diff_add = true
+          break
+        end
+      end
+      assert.is_true(has_diff_add)
+      delete_buffer(bufnr)
+    end)
   end)
 end)

spec/init_spec.lua

@@ -22,9 +22,15 @@ describe('fugitive-ts', function()
           debug = true,
           languages = { ['.envrc'] = 'bash' },
           disabled_languages = { 'markdown' },
-          highlight_headers = false,
           debounce_ms = 100,
           max_lines_per_hunk = 1000,
+          conceal_prefixes = false,
+          highlights = {
+            treesitter = true,
+            background = true,
+            linenr = true,
+            vim = false,
+          },
         })
       end)
     end)