From 21b8cfb470df79eac831c6e80f8b633c64ff788f Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sun, 1 Feb 2026 17:38:32 -0500
Subject: [PATCH 1/5] feat: add the entire plugin

---
 README.md                     |  16 +++--
 doc/fugitive-ts.nvim.txt      |  69 +++++++++++++++++++++
 lua/fugitive-ts/health.lua    |  41 +++++++++++++
 lua/fugitive-ts/highlight.lua |  52 ++++++++++++++++
 lua/fugitive-ts/init.lua      | 109 ++++++++++++++++++++++++++++++++++
 lua/fugitive-ts/parser.lua    |  89 +++++++++++++++++++++++++++
 plugin/fugitive-ts.lua        |  11 ++++
 7 files changed, 382 insertions(+), 5 deletions(-)
 create mode 100644 doc/fugitive-ts.nvim.txt
 create mode 100644 lua/fugitive-ts/health.lua
 create mode 100644 lua/fugitive-ts/highlight.lua
 create mode 100644 lua/fugitive-ts/init.lua
 create mode 100644 lua/fugitive-ts/parser.lua
 create mode 100644 plugin/fugitive-ts.lua

diff --git a/README.md b/README.md
index 871ab74..adad924 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,9 @@ Treesitter syntax highlighting for vim-fugitive diff views.
 
 ## Problem
 
-vim-fugitive uses regex-based `syntax/diff.vim` for highlighting expanded diffs in the status buffer. This means code inside diffs has no language-aware highlighting:
+vim-fugitive uses regex-based `syntax/diff.vim` for highlighting expanded diffs
+in the status buffer. This means code inside diffs has no language-aware
+highlighting:
 
 ```
 Unstaged (1)
@@ -17,7 +19,9 @@ M lua/mymodule.lua
 
 ## Solution
 
-Hook into fugitive's buffer, detect diff hunks, extract the language from filenames, and apply treesitter highlights as extmarks on top of fugitive's existing highlighting.
+Hook into fugitive's buffer, detect diff hunks, extract the language from
+filenames, and apply treesitter highlights as extmarks on top of fugitive's
+existing highlighting.
 
 ```
 Unstaged (1)
@@ -66,6 +70,7 @@ Staged (N)
 ```
 
 Pattern to detect:
+
 - Filename: `^[MADRC?] .+%.(%w+)$` → captures extension
 - Hunk header: `^@@ .+ @@`
 - Code lines: after hunk header, lines starting with ` `, `+`, or `-`
@@ -154,7 +159,8 @@ end
 
 ### 6. Re-highlight on Buffer Change
 
-Fugitive modifies the buffer when user expands/collapses diffs. Need to re-parse:
+Fugitive modifies the buffer when user expands/collapses diffs. Need to
+re-parse:
 
 ```lua
 vim.api.nvim_create_autocmd({"TextChanged", "TextChangedI"}, {
@@ -226,5 +232,5 @@ require("fugitive-ts").setup({
 
 - [Neovim Treesitter API](https://neovim.io/doc/user/treesitter.html)
 - [vim-fugitive User events](https://github.com/tpope/vim-fugitive/blob/master/doc/fugitive.txt)
-- [nvim_buf_set_extmark](https://neovim.io/doc/user/api.html#nvim_buf_set_extmark())
-- [vim.treesitter.get_string_parser](https://neovim.io/doc/user/treesitter.html#vim.treesitter.get_string_parser())
+- [nvim_buf_set_extmark](<https://neovim.io/doc/user/api.html#nvim_buf_set_extmark()>)
+- [vim.treesitter.get_string_parser](<https://neovim.io/doc/user/treesitter.html#vim.treesitter.get_string_parser()>)
diff --git a/doc/fugitive-ts.nvim.txt b/doc/fugitive-ts.nvim.txt
new file mode 100644
index 0000000..8fb052d
--- /dev/null
+++ b/doc/fugitive-ts.nvim.txt
@@ -0,0 +1,69 @@
+*fugitive-ts.nvim.txt*        Treesitter highlighting for vim-fugitive diffs
+
+Author:  Barrett Ruth <br.barrettruth@gmail.com>
+License: MIT
+
+==============================================================================
+INTRODUCTION                                                   *fugitive-ts.nvim*
+
+fugitive-ts.nvim adds treesitter-based syntax highlighting to vim-fugitive
+diff views. It overlays language-aware highlights on top of fugitive's
+default regex-based diff highlighting.
+
+==============================================================================
+REQUIREMENTS                                          *fugitive-ts-requirements*
+
+- Neovim 0.9.0+
+- vim-fugitive
+- Treesitter parsers for languages you want highlighted
+
+==============================================================================
+SETUP                                                        *fugitive-ts-setup*
+
+>lua
+    require('fugitive-ts').setup({
+      -- Enable/disable highlighting (default: true)
+      enabled = true,
+
+      -- Custom filename -> language mappings (optional)
+      languages = {},
+
+      -- Debounce delay in ms (default: 50)
+      debounce_ms = 50,
+    })
+<
+
+==============================================================================
+COMMANDS                                                  *fugitive-ts-commands*
+
+This plugin works automatically when you open a fugitive buffer. No commands
+are required.
+
+==============================================================================
+API                                                            *fugitive-ts-api*
+
+                                                    *fugitive-ts.setup()*
+setup({opts})
+    Configure the plugin. See |fugitive-ts-setup| for options.
+
+                                                   *fugitive-ts.attach()*
+attach({bufnr})
+    Manually attach highlighting to a buffer. Called automatically for
+    fugitive buffers.
+
+                                                  *fugitive-ts.refresh()*
+refresh({bufnr})
+    Manually refresh highlighting for a buffer.
+
+==============================================================================
+ROADMAP                                                    *fugitive-ts-roadmap*
+
+Planned features and improvements:
+
+- Vim syntax fallback: For languages without treesitter parsers, fall back
+  to vim's built-in syntax highlighting via scratch buffers. This would
+  provide highlighting coverage for more languages at the cost of
+  implementation complexity.
+
+==============================================================================
+ vim:tw=78:ts=8:ft=help:norl:
diff --git a/lua/fugitive-ts/health.lua b/lua/fugitive-ts/health.lua
new file mode 100644
index 0000000..bdeebdd
--- /dev/null
+++ b/lua/fugitive-ts/health.lua
@@ -0,0 +1,41 @@
+local M = {}
+
+function M.check()
+  vim.health.start('fugitive-ts.nvim')
+
+  if vim.fn.has('nvim-0.9.0') == 1 then
+    vim.health.ok('Neovim 0.9.0+ detected')
+  else
+    vim.health.error('fugitive-ts.nvim requires Neovim 0.9.0+')
+  end
+
+  local fugitive_loaded = vim.fn.exists(':Git') == 2
+  if fugitive_loaded then
+    vim.health.ok('vim-fugitive detected')
+  else
+    vim.health.warn('vim-fugitive not detected (required for this plugin to be useful)')
+  end
+
+  local common_langs = { 'lua', 'python', 'javascript', 'typescript', 'rust', 'go', 'c', 'cpp' }
+  local available = {}
+  local missing = {}
+
+  for _, lang in ipairs(common_langs) do
+    local ok = pcall(vim.treesitter.language.inspect, lang)
+    if ok then
+      table.insert(available, lang)
+    else
+      table.insert(missing, lang)
+    end
+  end
+
+  if #available > 0 then
+    vim.health.ok('Treesitter parsers available: ' .. table.concat(available, ', '))
+  end
+
+  if #missing > 0 then
+    vim.health.info('Treesitter parsers not installed: ' .. table.concat(missing, ', '))
+  end
+end
+
+return M
diff --git a/lua/fugitive-ts/highlight.lua b/lua/fugitive-ts/highlight.lua
new file mode 100644
index 0000000..650436d
--- /dev/null
+++ b/lua/fugitive-ts/highlight.lua
@@ -0,0 +1,52 @@
+local M = {}
+
+function M.highlight_hunk(bufnr, ns, hunk)
+  local lang = hunk.lang
+  if not lang then
+    return
+  end
+
+  local code_lines = {}
+  for _, line in ipairs(hunk.lines) do
+    table.insert(code_lines, line:sub(2))
+  end
+
+  local code = table.concat(code_lines, '\n')
+  if code == '' then
+    return
+  end
+
+  local ok, parser_obj = pcall(vim.treesitter.get_string_parser, code, lang)
+  if not ok or not parser_obj then
+    return
+  end
+
+  local trees = parser_obj:parse()
+  if not trees or #trees == 0 then
+    return
+  end
+
+  local query = vim.treesitter.query.get(lang, 'highlights')
+  if not query then
+    return
+  end
+
+  for id, node, _ in query:iter_captures(trees[1]:root(), code) do
+    local capture_name = '@' .. query.captures[id]
+    local sr, sc, er, ec = node:range()
+
+    local buf_sr = hunk.start_line + sr
+    local buf_er = hunk.start_line + er
+    local buf_sc = sc + 1
+    local buf_ec = ec + 1
+
+    pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_sr, buf_sc, {
+      end_row = buf_er,
+      end_col = buf_ec,
+      hl_group = capture_name,
+      priority = 200,
+    })
+  end
+end
+
+return M
diff --git a/lua/fugitive-ts/init.lua b/lua/fugitive-ts/init.lua
new file mode 100644
index 0000000..9bc5d7a
--- /dev/null
+++ b/lua/fugitive-ts/init.lua
@@ -0,0 +1,109 @@
+---@class fugitive-ts.Config
+---@field enabled boolean
+---@field languages table<string, string>
+---@field debounce_ms integer
+
+---@class fugitive-ts
+---@field attach fun(bufnr?: integer)
+---@field refresh fun(bufnr?: integer)
+---@field setup fun(opts?: fugitive-ts.Config)
+local M = {}
+
+local highlight = require('fugitive-ts.highlight')
+local parser = require('fugitive-ts.parser')
+
+local ns = vim.api.nvim_create_namespace('fugitive_ts')
+
+---@type fugitive-ts.Config
+local default_config = {
+  enabled = true,
+  languages = {},
+  debounce_ms = 50,
+}
+
+---@type fugitive-ts.Config
+local config = vim.deepcopy(default_config)
+
+---@type table<integer, boolean>
+local attached_buffers = {}
+
+---@param bufnr integer
+local function highlight_buffer(bufnr)
+  if not config.enabled then
+    return
+  end
+
+  if not vim.api.nvim_buf_is_valid(bufnr) then
+    return
+  end
+
+  vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
+
+  local hunks = parser.parse_buffer(bufnr, config.languages)
+  for _, hunk in ipairs(hunks) do
+    highlight.highlight_hunk(bufnr, ns, hunk)
+  end
+end
+
+---@param bufnr integer
+---@return fun()
+local function create_debounced_highlight(bufnr)
+  ---@type uv_timer_t?
+  local timer = nil
+  return function()
+    if timer then
+      timer:stop()
+      timer:close()
+    end
+    timer = vim.uv.new_timer()
+    timer:start(
+      config.debounce_ms,
+      0,
+      vim.schedule_wrap(function()
+        timer:close()
+        timer = nil
+        highlight_buffer(bufnr)
+      end)
+    )
+  end
+end
+
+---@param bufnr? integer
+function M.attach(bufnr)
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+
+  if attached_buffers[bufnr] then
+    return
+  end
+  attached_buffers[bufnr] = true
+
+  local debounced = create_debounced_highlight(bufnr)
+
+  highlight_buffer(bufnr)
+
+  vim.api.nvim_create_autocmd({ 'TextChanged', 'TextChangedI' }, {
+    buffer = bufnr,
+    callback = debounced,
+  })
+
+  vim.api.nvim_create_autocmd('BufWipeout', {
+    buffer = bufnr,
+    callback = function()
+      attached_buffers[bufnr] = nil
+    end,
+  })
+end
+
+---@param bufnr? integer
+function M.refresh(bufnr)
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+  highlight_buffer(bufnr)
+end
+
+---@param opts? fugitive-ts.Config
+function M.setup(opts)
+  opts = opts or {}
+  config = vim.tbl_deep_extend('force', default_config, opts)
+end
+
+return M
diff --git a/lua/fugitive-ts/parser.lua b/lua/fugitive-ts/parser.lua
new file mode 100644
index 0000000..7ca5cb5
--- /dev/null
+++ b/lua/fugitive-ts/parser.lua
@@ -0,0 +1,89 @@
+---@class fugitive-ts.Hunk
+---@field filename string
+---@field lang string
+---@field start_line integer
+---@field lines string[]
+
+local M = {}
+
+---@param filename string
+---@param custom_langs? table<string, string>
+---@return string?
+local function get_lang_from_filename(filename, custom_langs)
+  if custom_langs and custom_langs[filename] then
+    return custom_langs[filename]
+  end
+
+  local ft = vim.filetype.match({ filename = filename })
+  if not ft then
+    return nil
+  end
+
+  local lang = vim.treesitter.language.get_lang(ft)
+  if lang then
+    local ok = pcall(vim.treesitter.language.inspect, lang)
+    if ok then
+      return lang
+    end
+  end
+
+  return nil
+end
+
+---@param bufnr integer
+---@param custom_langs? table<string, string>
+---@return fugitive-ts.Hunk[]
+function M.parse_buffer(bufnr, custom_langs)
+  local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
+  ---@type fugitive-ts.Hunk[]
+  local hunks = {}
+
+  ---@type string?
+  local current_filename = nil
+  ---@type string?
+  local current_lang = nil
+  ---@type integer?
+  local hunk_start = nil
+  ---@type string[]
+  local hunk_lines = {}
+
+  local function flush_hunk()
+    if hunk_start and #hunk_lines > 0 and current_lang then
+      table.insert(hunks, {
+        filename = current_filename,
+        lang = current_lang,
+        start_line = hunk_start,
+        lines = hunk_lines,
+      })
+    end
+    hunk_start = nil
+    hunk_lines = {}
+  end
+
+  for i, line in ipairs(lines) do
+    local filename = line:match('^[MADRC%?!]%s+(.+)$')
+    if filename then
+      flush_hunk()
+      current_filename = filename
+      current_lang = get_lang_from_filename(filename, custom_langs)
+    elseif line:match('^@@.-@@') then
+      flush_hunk()
+      hunk_start = i
+    elseif hunk_start then
+      local prefix = line:sub(1, 1)
+      if prefix == ' ' or prefix == '+' or prefix == '-' then
+        table.insert(hunk_lines, line)
+      elseif line == '' or line:match('^[MADRC%?!]%s+') or line:match('^%a') then
+        flush_hunk()
+        current_filename = nil
+        current_lang = nil
+      end
+    end
+  end
+
+  flush_hunk()
+
+  return hunks
+end
+
+return M
diff --git a/plugin/fugitive-ts.lua b/plugin/fugitive-ts.lua
new file mode 100644
index 0000000..cfe7a03
--- /dev/null
+++ b/plugin/fugitive-ts.lua
@@ -0,0 +1,11 @@
+if vim.g.loaded_fugitive_ts then
+  return
+end
+vim.g.loaded_fugitive_ts = 1
+
+vim.api.nvim_create_autocmd('FileType', {
+  pattern = 'fugitive',
+  callback = function(args)
+    require('fugitive-ts').attach(args.buf)
+  end,
+})

From 29f9a5f7e4bfc6fd1b9b3ba475c042400c82ec85 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sun, 1 Feb 2026 17:38:58 -0500
Subject: [PATCH 2/5] feat: luacats annotations

---
 lua/fugitive-ts/health.lua    | 3 +++
 lua/fugitive-ts/highlight.lua | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/lua/fugitive-ts/health.lua b/lua/fugitive-ts/health.lua
index bdeebdd..48f946b 100644
--- a/lua/fugitive-ts/health.lua
+++ b/lua/fugitive-ts/health.lua
@@ -16,8 +16,11 @@ function M.check()
     vim.health.warn('vim-fugitive not detected (required for this plugin to be useful)')
   end
 
+  ---@type string[]
   local common_langs = { 'lua', 'python', 'javascript', 'typescript', 'rust', 'go', 'c', 'cpp' }
+  ---@type string[]
   local available = {}
+  ---@type string[]
   local missing = {}
 
   for _, lang in ipairs(common_langs) do
diff --git a/lua/fugitive-ts/highlight.lua b/lua/fugitive-ts/highlight.lua
index 650436d..3c29658 100644
--- a/lua/fugitive-ts/highlight.lua
+++ b/lua/fugitive-ts/highlight.lua
@@ -1,11 +1,15 @@
 local M = {}
 
+---@param bufnr integer
+---@param ns integer
+---@param hunk fugitive-ts.Hunk
 function M.highlight_hunk(bufnr, ns, hunk)
   local lang = hunk.lang
   if not lang then
     return
   end
 
+  ---@type string[]
   local code_lines = {}
   for _, line in ipairs(hunk.lines) do
     table.insert(code_lines, line:sub(2))

From ae727159b9104557af72c79a7cf78e215cef154a Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sun, 1 Feb 2026 17:44:28 -0500
Subject: [PATCH 3/5] feat: debug option

---
 doc/fugitive-ts.nvim.txt      |  4 ++++
 lua/fugitive-ts/highlight.lua | 25 ++++++++++++++++++++++++-
 lua/fugitive-ts/init.lua      | 19 +++++++++++++++++--
 lua/fugitive-ts/parser.lua    | 26 +++++++++++++++++++++++---
 4 files changed, 68 insertions(+), 6 deletions(-)

diff --git a/doc/fugitive-ts.nvim.txt b/doc/fugitive-ts.nvim.txt
index 8fb052d..a825909 100644
--- a/doc/fugitive-ts.nvim.txt
+++ b/doc/fugitive-ts.nvim.txt
@@ -25,6 +25,10 @@ SETUP                                                        *fugitive-ts-setup*
       -- Enable/disable highlighting (default: true)
       enabled = true,
 
+      -- Enable debug logging (default: false)
+      -- Outputs to :messages with [fugitive-ts] prefix
+      debug = false,
+
       -- Custom filename -> language mappings (optional)
       languages = {},
 
diff --git a/lua/fugitive-ts/highlight.lua b/lua/fugitive-ts/highlight.lua
index 3c29658..c77a3fa 100644
--- a/lua/fugitive-ts/highlight.lua
+++ b/lua/fugitive-ts/highlight.lua
@@ -1,9 +1,17 @@
 local M = {}
 
+---@param msg string
+---@param ... any
+local function dbg(msg, ...)
+  local formatted = string.format(msg, ...)
+  vim.notify('[fugitive-ts] ' .. formatted, vim.log.levels.DEBUG)
+end
+
 ---@param bufnr integer
 ---@param ns integer
 ---@param hunk fugitive-ts.Hunk
-function M.highlight_hunk(bufnr, ns, hunk)
+---@param debug? boolean
+function M.highlight_hunk(bufnr, ns, hunk, debug)
   local lang = hunk.lang
   if not lang then
     return
@@ -22,19 +30,29 @@ function M.highlight_hunk(bufnr, ns, hunk)
 
   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)
+    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)
+    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)
+    end
     return
   end
 
+  local extmark_count = 0
   for id, node, _ in query:iter_captures(trees[1]:root(), code) do
     local capture_name = '@' .. query.captures[id]
     local sr, sc, er, ec = node:range()
@@ -50,6 +68,11 @@ function M.highlight_hunk(bufnr, ns, hunk)
       hl_group = capture_name,
       priority = 200,
     })
+    extmark_count = extmark_count + 1
+  end
+
+  if debug then
+    dbg('hunk %s:%d applied %d extmarks', hunk.filename, hunk.start_line, extmark_count)
   end
 end
 
diff --git a/lua/fugitive-ts/init.lua b/lua/fugitive-ts/init.lua
index 9bc5d7a..8bd4977 100644
--- a/lua/fugitive-ts/init.lua
+++ b/lua/fugitive-ts/init.lua
@@ -1,5 +1,6 @@
 ---@class fugitive-ts.Config
 ---@field enabled boolean
+---@field debug boolean
 ---@field languages table<string, string>
 ---@field debounce_ms integer
 
@@ -17,6 +18,7 @@ local ns = vim.api.nvim_create_namespace('fugitive_ts')
 ---@type fugitive-ts.Config
 local default_config = {
   enabled = true,
+  debug = false,
   languages = {},
   debounce_ms = 50,
 }
@@ -27,6 +29,16 @@ local config = vim.deepcopy(default_config)
 ---@type table<integer, boolean>
 local attached_buffers = {}
 
+---@param msg string
+---@param ... any
+local function dbg(msg, ...)
+  if not config.debug then
+    return
+  end
+  local formatted = string.format(msg, ...)
+  vim.notify('[fugitive-ts] ' .. formatted, vim.log.levels.DEBUG)
+end
+
 ---@param bufnr integer
 local function highlight_buffer(bufnr)
   if not config.enabled then
@@ -39,9 +51,10 @@ local function highlight_buffer(bufnr)
 
   vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
 
-  local hunks = parser.parse_buffer(bufnr, config.languages)
+  local hunks = parser.parse_buffer(bufnr, config.languages, config.debug)
+  dbg('found %d hunks in buffer %d', #hunks, bufnr)
   for _, hunk in ipairs(hunks) do
-    highlight.highlight_hunk(bufnr, ns, hunk)
+    highlight.highlight_hunk(bufnr, ns, hunk, config.debug)
   end
 end
 
@@ -77,6 +90,8 @@ function M.attach(bufnr)
   end
   attached_buffers[bufnr] = true
 
+  dbg('attaching to buffer %d', bufnr)
+
   local debounced = create_debounced_highlight(bufnr)
 
   highlight_buffer(bufnr)
diff --git a/lua/fugitive-ts/parser.lua b/lua/fugitive-ts/parser.lua
index 7ca5cb5..fec0dda 100644
--- a/lua/fugitive-ts/parser.lua
+++ b/lua/fugitive-ts/parser.lua
@@ -6,16 +6,27 @@
 
 local M = {}
 
+---@param msg string
+---@param ... any
+local function dbg(msg, ...)
+  local formatted = string.format(msg, ...)
+  vim.notify('[fugitive-ts] ' .. formatted, vim.log.levels.DEBUG)
+end
+
 ---@param filename string
 ---@param custom_langs? table<string, string>
+---@param debug? boolean
 ---@return string?
-local function get_lang_from_filename(filename, custom_langs)
+local function get_lang_from_filename(filename, custom_langs, debug)
   if custom_langs and custom_langs[filename] then
     return custom_langs[filename]
   end
 
   local ft = vim.filetype.match({ filename = filename })
   if not ft then
+    if debug then
+      dbg('no filetype for: %s', filename)
+    end
     return nil
   end
 
@@ -25,6 +36,11 @@ local function get_lang_from_filename(filename, custom_langs)
     if ok then
       return lang
     end
+    if debug then
+      dbg('no parser for lang: %s (ft: %s)', lang, ft)
+    end
+  elseif debug then
+    dbg('no ts lang for filetype: %s', ft)
   end
 
   return nil
@@ -32,8 +48,9 @@ end
 
 ---@param bufnr integer
 ---@param custom_langs? table<string, string>
+---@param debug? boolean
 ---@return fugitive-ts.Hunk[]
-function M.parse_buffer(bufnr, custom_langs)
+function M.parse_buffer(bufnr, custom_langs, debug)
   local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
   ---@type fugitive-ts.Hunk[]
   local hunks = {}
@@ -65,7 +82,10 @@ function M.parse_buffer(bufnr, custom_langs)
     if filename then
       flush_hunk()
       current_filename = filename
-      current_lang = get_lang_from_filename(filename, custom_langs)
+      current_lang = get_lang_from_filename(filename, custom_langs, debug)
+      if debug and current_lang then
+        dbg('file: %s -> lang: %s', filename, current_lang)
+      end
     elseif line:match('^@@.-@@') then
       flush_hunk()
       hunk_start = i

From 0e86f45c39e88bbabdc9da80cd9ee50a1e2c63ec Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sun, 1 Feb 2026 18:52:00 -0500
Subject: [PATCH 4/5] feat: add some config options

---
 doc/fugitive-ts.nvim.txt      |  4 ++++
 lua/fugitive-ts/highlight.lua | 28 +++++++++++++++++++++++++++-
 lua/fugitive-ts/init.lua      | 12 +++++++++++-
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/doc/fugitive-ts.nvim.txt b/doc/fugitive-ts.nvim.txt
index a825909..f91fb09 100644
--- a/doc/fugitive-ts.nvim.txt
+++ b/doc/fugitive-ts.nvim.txt
@@ -34,6 +34,10 @@ SETUP                                                        *fugitive-ts-setup*
 
       -- Debounce delay in ms (default: 50)
       debounce_ms = 50,
+
+      -- Max lines per hunk before skipping treesitter (default: 500)
+      -- Prevents lag on large diffs
+      max_lines_per_hunk = 500,
     })
 <
 
diff --git a/lua/fugitive-ts/highlight.lua b/lua/fugitive-ts/highlight.lua
index c77a3fa..ea292d0 100644
--- a/lua/fugitive-ts/highlight.lua
+++ b/lua/fugitive-ts/highlight.lua
@@ -10,13 +10,27 @@ end
 ---@param bufnr integer
 ---@param ns integer
 ---@param hunk fugitive-ts.Hunk
+---@param max_lines integer
 ---@param debug? boolean
-function M.highlight_hunk(bufnr, ns, hunk, debug)
+function M.highlight_hunk(bufnr, ns, hunk, max_lines, debug)
   local lang = hunk.lang
   if not lang then
     return
   end
 
+  if #hunk.lines > max_lines then
+    if debug then
+      dbg(
+        'skipping hunk %s:%d (%d lines > %d max)',
+        hunk.filename,
+        hunk.start_line,
+        #hunk.lines,
+        max_lines
+      )
+    end
+    return
+  end
+
   ---@type string[]
   local code_lines = {}
   for _, line in ipairs(hunk.lines) do
@@ -52,6 +66,18 @@ function M.highlight_hunk(bufnr, ns, hunk, debug)
     return
   end
 
+  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
+      pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 1, {
+        end_col = line_len,
+        hl_group = 'Normal',
+        priority = 199,
+      })
+    end
+  end
+
   local extmark_count = 0
   for id, node, _ in query:iter_captures(trees[1]:root(), code) do
     local capture_name = '@' .. query.captures[id]
diff --git a/lua/fugitive-ts/init.lua b/lua/fugitive-ts/init.lua
index 8bd4977..e6de719 100644
--- a/lua/fugitive-ts/init.lua
+++ b/lua/fugitive-ts/init.lua
@@ -3,6 +3,7 @@
 ---@field debug boolean
 ---@field languages table<string, string>
 ---@field debounce_ms integer
+---@field max_lines_per_hunk integer
 
 ---@class fugitive-ts
 ---@field attach fun(bufnr?: integer)
@@ -21,6 +22,7 @@ local default_config = {
   debug = false,
   languages = {},
   debounce_ms = 50,
+  max_lines_per_hunk = 500,
 }
 
 ---@type fugitive-ts.Config
@@ -54,7 +56,7 @@ local function highlight_buffer(bufnr)
   local hunks = parser.parse_buffer(bufnr, config.languages, config.debug)
   dbg('found %d hunks in buffer %d', #hunks, bufnr)
   for _, hunk in ipairs(hunks) do
-    highlight.highlight_hunk(bufnr, ns, hunk, config.debug)
+    highlight.highlight_hunk(bufnr, ns, hunk, config.max_lines_per_hunk, config.debug)
   end
 end
 
@@ -101,6 +103,14 @@ function M.attach(bufnr)
     callback = debounced,
   })
 
+  vim.api.nvim_create_autocmd('Syntax', {
+    buffer = bufnr,
+    callback = function()
+      dbg('syntax event, re-highlighting buffer %d', bufnr)
+      highlight_buffer(bufnr)
+    end,
+  })
+
   vim.api.nvim_create_autocmd('BufWipeout', {
     buffer = bufnr,
     callback = function()

From 8d8a09635c25ac84bc5696cc74e832d15b77d630 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sun, 1 Feb 2026 19:03:52 -0500
Subject: [PATCH 5/5] fix: correct ci

---
 .github/workflows/luarocks.yaml | 2 +-
 .pre-commit-config.yaml         | 2 +-
 lua/fugitive-ts/init.lua        | 5 ++---
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/luarocks.yaml b/.github/workflows/luarocks.yaml
index 9f934a5..9b6664e 100644
--- a/.github/workflows/luarocks.yaml
+++ b/.github/workflows/luarocks.yaml
@@ -3,7 +3,7 @@ name: luarocks
 on:
   push:
     tags:
-      - "v*"
+      - 'v*'
 
 jobs:
   quality:
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index b9f6659..2edf043 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -14,4 +14,4 @@ repos:
     hooks:
       - id: prettier
         name: prettier
-        files: \.(md|,toml,yaml,sh)$
+        files: \.(md|toml|yaml|sh)$
diff --git a/lua/fugitive-ts/init.lua b/lua/fugitive-ts/init.lua
index e6de719..4247062 100644
--- a/lua/fugitive-ts/init.lua
+++ b/lua/fugitive-ts/init.lua
@@ -63,12 +63,11 @@ end
 ---@param bufnr integer
 ---@return fun()
 local function create_debounced_highlight(bufnr)
-  ---@type uv_timer_t?
   local timer = nil
   return function()
     if timer then
-      timer:stop()
-      timer:close()
+      timer:stop() ---@diagnostic disable-line: undefined-field
+      timer:close() ---@diagnostic disable-line: undefined-field
     end
     timer = vim.uv.new_timer()
     timer:start(