From 79f5059a2dd3fbe8e1496711c7a9da29bab4c776 Mon Sep 17 00:00:00 2001
From: Lewis Russell <lewis6991@gmail.com>
Date: Thu, 23 Feb 2023 11:16:10 +0000
Subject: [PATCH] perf: reduce startup time

---
 .github/workflows/ci.yml     |  25 +-
 Makefile                     |  15 +-
 gen_help.lua                 |   1 +
 lua/gitsigns.lua             | 513 ++++++++--------------------------
 lua/gitsigns/attach.lua      | 411 +++++++++++++++++++++++++++
 lua/gitsigns/cli.lua         |  43 +--
 lua/gitsigns/config.lua      |   6 +
 lua/gitsigns/debug.lua       | 141 ++--------
 lua/gitsigns/debug/log.lua   | 109 ++++++++
 lua/gitsigns/git.lua         |  73 ++---
 lua/gitsigns/highlight.lua   |   6 +-
 lua/gitsigns/manager.lua     |  71 +----
 lua/gitsigns/signs.lua       |   2 +-
 lua/gitsigns/status.lua      |   7 +-
 lua/gitsigns/subprocess.lua  |  10 +-
 teal/gitsigns.tl             | 521 ++++++++---------------------------
 teal/gitsigns/attach.tl      | 411 +++++++++++++++++++++++++++
 teal/gitsigns/cli.tl         |  49 ++--
 teal/gitsigns/config.tl      |   6 +
 teal/gitsigns/debug.tl       | 141 ++--------
 teal/gitsigns/debug/log.tl   | 109 ++++++++
 teal/gitsigns/git.tl         |  73 ++---
 teal/gitsigns/highlight.tl   |   6 +-
 teal/gitsigns/manager.tl     |  71 +----
 teal/gitsigns/signs.tl       |   2 +-
 teal/gitsigns/status.tl      |   7 +-
 teal/gitsigns/subprocess.tl  |  10 +-
 test/gitdir_watcher_spec.lua |  17 +-
 test/gitsigns_spec.lua       |  18 +-
 test/gs_helpers.lua          |  34 +--
 test/highlights_spec.lua     |   1 +
 types/vim.d.tl               |   4 +
 types/vim/api.d.tl           |  11 +-
 33 files changed, 1539 insertions(+), 1385 deletions(-)
 create mode 100644 lua/gitsigns/attach.lua
 create mode 100644 lua/gitsigns/debug/log.lua
 create mode 100644 teal/gitsigns/attach.tl
 create mode 100644 teal/gitsigns/debug/log.tl

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 85276448..b77808ca 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,9 +7,6 @@ on:
     branches: [ main ]
   workflow_dispatch:
 
-env:
-  CC: clang
-
 jobs:
   commit_lint:
     runs-on: ubuntu-latest
@@ -21,7 +18,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        neovim_branch: ['v0.7.2', 'v0.8.3', 'nightly']
+        neovim_branch: ['v0.8.3', 'nightly']
     runs-on: ubuntu-latest
     env:
       NEOVIM_BRANCH: ${{ matrix.neovim_branch }}
@@ -30,14 +27,6 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v3
 
-      - name: Install LuaJIT
-        uses: leafo/gh-actions-lua@v9
-        with:
-          luaVersion: "luajit-2.1.0-beta3"
-
-      - name: Install Luarocks
-        uses: leafo/gh-actions-luarocks@v4
-
       - name: Get Neovim SHA
         id: get-nvim-sha
         run: |
@@ -50,12 +39,6 @@ jobs:
           path: deps
           key: ${{ steps.get-nvim-sha.outputs.sha }}-${{ hashFiles('.github/workflows/ci.yml, Makefile') }}
 
-      - name: Install Lua Deps
-        run: make lua_deps
-
-      - name: Check lua files are built from latest teal
-        run: make tl-ensure
-
       - name: Install Neovim build dependencies
         if: steps.cache-deps.outputs.cache-hit != 'true'
         run: |
@@ -78,5 +61,11 @@ jobs:
         if: steps.cache-deps.outputs.cache-hit != 'true'
         run: make test_deps
 
+      - name: Install Lua Deps
+        run: make lua_deps
+
+      - name: Check lua files are built from latest teal
+        run: make tl-ensure
+
       - name: Run Test
         run: make test
diff --git a/Makefile b/Makefile
index 3cb7eb6e..26108416 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,6 @@
 
 export PJ_ROOT=$(PWD)
 
-# Suppress built in rules. This reduces clutter when running with -d
-MAKEFLAGS += --no-builtin-rules
-
 FILTER ?= .*
 
 LUA_VERSION   := 5.1
@@ -13,7 +10,7 @@ NEOVIM_BRANCH ?= master
 DEPS_DIR := $(PWD)/deps/nvim-$(NEOVIM_BRANCH)
 NVIM_DIR := $(DEPS_DIR)/neovim
 
-LUAROCKS       := luarocks --lua-version=$(LUA_VERSION)
+LUAROCKS       := $(DEPS_DIR)/luarocks/usr/bin/luarocks
 LUAROCKS_TREE  := $(DEPS_DIR)/luarocks/usr
 LUAROCKS_LPATH := $(LUAROCKS_TREE)/share/lua/$(LUA_VERSION)
 LUAROCKS_INIT  := eval $$($(LUAROCKS) --tree $(LUAROCKS_TREE) path) &&
@@ -23,25 +20,27 @@ LUAROCKS_INIT  := eval $$($(LUAROCKS) --tree $(LUAROCKS_TREE) path) &&
 $(NVIM_DIR):
 	@mkdir -p $(DEPS_DIR)
 	git clone --depth 1 https://github.com/neovim/neovim --branch $(NEOVIM_BRANCH) $@
+	@# disable LTO to reduce compile time
 	make -C $@ \
 		DEPS_BUILD_DIR=$(dir $(LUAROCKS_TREE)) \
-		CMAKE_BUILD_TYPE=RelWithDebInfo
+		CMAKE_BUILD_TYPE=RelWithDebInfo \
+		CMAKE_EXTRA_FLAGS='-DCI_BUILD=OFF -DENABLE_LTO=OFF'
 
 TL := $(LUAROCKS_TREE)/bin/tl
 
-$(TL):
+$(TL): $(NVIM_DIR)
 	@mkdir -p $$(dirname $@)
 	$(LUAROCKS) --tree $(LUAROCKS_TREE) install tl $(TL_VERSION)
 
 INSPECT := $(LUAROCKS_LPATH)/inspect.lua
 
-$(INSPECT):
+$(INSPECT): $(NVIM_DIR)
 	@mkdir -p $$(dirname $@)
 	$(LUAROCKS) --tree $(LUAROCKS_TREE) install inspect
 
 LUV := $(LUAROCKS_TREE)/lib/lua/$(LUA_VERSION)/luv.so
 
-$(LUV):
+$(LUV): $(NVIM_DIR)
 	@mkdir -p $$(dirname $@)
 	$(LUAROCKS) --tree $(LUAROCKS_TREE) install luv
 
diff --git a/gen_help.lua b/gen_help.lua
index b8e87b98..8a509f89 100755
--- a/gen_help.lua
+++ b/gen_help.lua
@@ -335,6 +335,7 @@ local function get_marker_text(marker)
     CONFIG    = gen_config_doc,
     FUNCTIONS = gen_functions_doc{
       'teal/gitsigns.tl',
+      'teal/gitsigns/attach.tl',
       'teal/gitsigns/actions.tl',
     },
     HIGHLIGHTS = gen_highlights_doc,
diff --git a/lua/gitsigns.lua b/lua/gitsigns.lua
index 7da40acb..02b31f2a 100644
--- a/lua/gitsigns.lua
+++ b/lua/gitsigns.lua
@@ -1,405 +1,159 @@
-local async = require('gitsigns.async')
 local void = require('gitsigns.async').void
 local scheduler = require('gitsigns.async').scheduler
 
-local Status = require("gitsigns.status")
-local git = require('gitsigns.git')
-local manager = require('gitsigns.manager')
-local util = require('gitsigns.util')
-local hl = require('gitsigns.highlight')
-
-local gs_cache = require('gitsigns.cache')
-local cache = gs_cache.cache
-local CacheEntry = gs_cache.CacheEntry
-
 local gs_config = require('gitsigns.config')
 local Config = gs_config.Config
 local config = gs_config.config
 
-local gs_debug = require("gitsigns.debug")
-local dprintf = gs_debug.dprintf
-local dprint = gs_debug.dprint
-
-local Debounce = require("gitsigns.debounce")
-local debounce_trailing = Debounce.debounce_trailing
-local throttle_by_id = Debounce.throttle_by_id
+local log = require('gitsigns.debug.log')
+local dprintf = log.dprintf
+local dprint = log.dprint
 
 local api = vim.api
-local uv = vim.loop
-local current_buf = api.nvim_get_current_buf
-
-local M = {GitContext = {}, }
-
-
-
-
-
-
-
+local uv = require('gitsigns.uv')
 
+local M = {}
 
 
+   -- from attach.tl
 
 
 
 
-local GitContext = M.GitContext
 
---- Detach Gitsigns from all buffers it is attached to.
-function M.detach_all()
-   for k, _ in pairs(cache) do
-      M.detach(k)
-   end
-end
+local cwd_watcher
 
---- Detach Gitsigns from the buffer {bufnr}. If {bufnr} is not
---- provided then the current buffer is used.
----
---- Parameters: ~
----       {bufnr}   (number): Buffer number
-function M.detach(bufnr, _keep_signs)
-   -- When this is called interactively (with no arguments) we want to remove all
-   -- the signs, however if called via a detach event (due to nvim_buf_attach)
-   -- then we don't want to clear the signs in case the buffer is just being
-   -- updated due to the file externally changing. When this happens a detach and
-   -- attach event happen in sequence and so we keep the old signs to stop the
-   -- sign column width moving about between updates.
-   bufnr = bufnr or current_buf()
-   dprint('Detached')
-   local bcache = cache[bufnr]
-   if not bcache then
-      dprint('Cache was nil')
-      return
-   end
-
-   manager.detach(bufnr, _keep_signs)
-
-   -- Clear status variables
-   Status:clear(bufnr)
-
-   cache:destroy(bufnr)
-end
+local update_cwd_head = void(function()
+   local paths = vim.fs.find('.git', {
+      limit = 1,
+      upward = true,
+      type = 'directory',
+   })
 
--- @return (string, string) Tuple of buffer name and commit
-local function parse_fugitive_uri(name)
-   if vim.fn.exists('*FugitiveReal') == 0 then
-      dprint("Fugitive not installed")
+   if #paths == 0 then
       return
    end
 
-   local path = vim.fn.FugitiveReal(name)
-   local commit = vim.fn.FugitiveParse(name)[1]:match('([^:]+):.*')
-   if commit == '0' then
-      -- '0' means the index so clear commit so we attach normally
-      commit = nil
+   if cwd_watcher then
+      cwd_watcher:stop()
+   else
+      cwd_watcher = uv.new_fs_poll(true)
    end
-   return path, commit
-end
 
-local function parse_gitsigns_uri(name)
-   -- TODO(lewis6991): Support submodules
-   local _, _, root_path, commit, rel_path = 
-   name:find([[^gitsigns://(.*)/%.git/(.*):(.*)]])
-   if commit == ':0' then
-      -- ':0' means the index so clear commit so we attach normally
-      commit = nil
-   end
-   if root_path then
-      name = root_path .. '/' .. rel_path
-   end
-   return name, commit
-end
+   local cwd = vim.loop.cwd()
+   local gitdir, head
 
-local function get_buf_path(bufnr)
-   local file = 
-   uv.fs_realpath(api.nvim_buf_get_name(bufnr)) or
-
-   api.nvim_buf_call(bufnr, function()
-      return vim.fn.expand('%:p')
-   end)
-
-   if not vim.wo.diff then
-      if vim.startswith(file, 'fugitive://') then
-         local path, commit = parse_fugitive_uri(file)
-         dprintf("Fugitive buffer for file '%s' from path '%s'", path, file)
-         path = uv.fs_realpath(path)
-         if path then
-            return path, commit
-         end
-      end
+   local gs_cache = require('gitsigns.cache')
 
-      if vim.startswith(file, 'gitsigns://') then
-         local path, commit = parse_gitsigns_uri(file)
-         dprintf("Gitsigns buffer for file '%s' from path '%s'", path, file)
-         path = uv.fs_realpath(path)
-         if path then
-            return path, commit
-         end
+   -- Look in the cache first
+   for _, bcache in pairs(gs_cache.cache) do
+      local repo = bcache.git_obj.repo
+      if repo.toplevel == cwd then
+         head = repo.abbrev_head
+         gitdir = repo.gitdir
+         break
       end
    end
 
-   return file
-end
+   local git = require('gitsigns.git')
 
-local vimgrep_running = false
-
-local function on_lines(_, bufnr, _, first, last_orig, last_new, byte_count)
-   if first == last_orig and last_orig == last_new and byte_count == 0 then
-      -- on_lines can be called twice for undo events; ignore the second
-      -- call which indicates no changes.
-      return
+   if not head or not gitdir then
+      local info = git.get_repo_info(cwd)
+      gitdir = info.gitdir
+      head = info.abbrev_head
    end
-   return manager.on_lines(bufnr, first, last_orig, last_new)
-end
-
-local function on_reload(_, bufnr)
-   local __FUNC__ = 'on_reload'
-   dprint('Reload')
-   manager.update_debounced(bufnr)
-end
-
-local function on_detach(_, bufnr)
-   M.detach(bufnr, true)
-end
 
-local function on_attach_pre(bufnr)
-   local gitdir, toplevel
-   if config._on_attach_pre then
-      local res = async.wrap(config._on_attach_pre, 2)(bufnr)
-      dprintf('ran on_attach_pre with result %s', vim.inspect(res))
-      if type(res) == "table" then
-         if type(res.gitdir) == 'string' then
-            gitdir = res.gitdir
-         end
-         if type(res.toplevel) == 'string' then
-            toplevel = res.toplevel
-         end
-      end
-   end
-   return gitdir, toplevel
-end
+   scheduler()
+   vim.g.gitsigns_head = head
 
-local function try_worktrees(_bufnr, file, encoding)
-   if not config.worktrees then
+   if not gitdir then
       return
    end
 
-   for _, wt in ipairs(config.worktrees) do
-      local git_obj = git.Obj.new(file, encoding, wt.gitdir, wt.toplevel)
-      if git_obj and git_obj.object_name then
-         dprintf('Using worktree %s', vim.inspect(wt))
-         return git_obj
-      end
-   end
-end
+   local towatch = gitdir .. '/HEAD'
 
--- Ensure attaches cannot be interleaved.
--- Since attaches are asynchronous we need to make sure an attach isn't
--- performed whilst another one is in progress.
-local attach_throttled = throttle_by_id(function(cbuf, ctx, aucmd)
-   local __FUNC__ = 'attach'
-   if vimgrep_running then
-      dprint('attaching is disabled')
+   if cwd_watcher:getpath() == towatch then
+      -- Already watching
       return
    end
 
-   if cache[cbuf] then
-      dprint('Already attached')
-      return
-   end
-
-   if aucmd then
-      dprintf('Attaching (trigger=%s)', aucmd)
-   else
-      dprint('Attaching')
-   end
-
-   if not api.nvim_buf_is_loaded(cbuf) then
-      dprint('Non-loaded buffer')
-      return
-   end
-
-   local encoding = vim.bo[cbuf].fileencoding
-   if encoding == '' then
-      encoding = 'utf-8'
-   end
-   local file
-   local commit
-   local gitdir_oap
-   local toplevel_oap
-
-   if ctx then
-      gitdir_oap = ctx.gitdir
-      toplevel_oap = ctx.toplevel
-      file = ctx.toplevel .. util.path_sep .. ctx.file
-      commit = ctx.commit
-   else
-      if api.nvim_buf_line_count(cbuf) > config.max_file_length then
-         dprint('Exceeds max_file_length')
-         return
-      end
-
-      if vim.bo[cbuf].buftype ~= '' then
-         dprint('Non-normal buffer')
-         return
-      end
-
-      file, commit = get_buf_path(cbuf)
-      local file_dir = util.dirname(file)
-
-      if not file_dir or not util.path_exists(file_dir) then
-         dprint('Not a path')
+   -- Watch .git/HEAD to detect branch changes
+   cwd_watcher:start(
+   towatch,
+   config.watch_gitdir.interval,
+   void(function(err)
+      local __FUNC__ = 'cwd_watcher_cb'
+      if err then
+         dprintf('Git dir update error: %s', err)
          return
       end
+      dprint('Git cwd dir update')
 
-      gitdir_oap, toplevel_oap = on_attach_pre(cbuf)
-   end
-
-   local git_obj = git.Obj.new(file, encoding, gitdir_oap, toplevel_oap)
-
-   if not git_obj and not ctx then
-      git_obj = try_worktrees(cbuf, file, encoding)
+      local new_head = git.get_repo_info(cwd).abbrev_head
       scheduler()
-   end
-
-   if not git_obj then
-      dprint('Empty git obj')
-      return
-   end
-   local repo = git_obj.repo
-
-   scheduler()
-   Status:update(cbuf, {
-      head = repo.abbrev_head,
-      root = repo.toplevel,
-      gitdir = repo.gitdir,
-   })
-
-   if vim.startswith(file, repo.gitdir .. util.path_sep) then
-      dprint('In non-standard git dir')
-      return
-   end
-
-   if not ctx and (not util.path_exists(file) or uv.fs_stat(file).type == 'directory') then
-      dprint('Not a file')
-      return
-   end
-
-   if not git_obj.relpath then
-      dprint('Cannot resolve file in repo')
-      return
-   end
-
-   if not config.attach_to_untracked and git_obj.object_name == nil then
-      dprint('File is untracked')
-      return
-   end
-
-   -- On windows os.tmpname() crashes in callback threads so initialise this
-   -- variable on the main thread.
-   scheduler()
-
-   if config.on_attach and config.on_attach(cbuf) == false then
-      dprint('User on_attach() returned false')
-      return
-   end
-
-   cache[cbuf] = CacheEntry.new({
-      base = ctx and ctx.base or config.base,
-      file = file,
-      commit = commit,
-      gitdir_watcher = manager.watch_gitdir(cbuf, repo.gitdir),
-      git_obj = git_obj,
-   })
-
-   if not api.nvim_buf_is_loaded(cbuf) then
-      dprint('Un-loaded buffer')
-      return
-   end
-
-   -- Make sure to attach before the first update (which is async) so we pick up
-   -- changes from BufReadCmd.
-   api.nvim_buf_attach(cbuf, false, {
-      on_lines = on_lines,
-      on_reload = on_reload,
-      on_detach = on_detach,
-   })
+      vim.g.gitsigns_head = new_head
+   end))
 
-   -- Initial update
-   manager.update(cbuf, cache[cbuf])
-
-   if config.keymaps and not vim.tbl_isempty(config.keymaps) then
-      require('gitsigns.mappings')(config.keymaps, cbuf)
-   end
-end)
-
---- Attach Gitsigns to the buffer.
----
---- Attributes: ~
----       {async}
----
---- Parameters: ~
----       {bufnr}   (number): Buffer number
----       {ctx}      (table|nil):
----                     Git context data that may optionally be used to attach to any
----                     buffer that represents a real git object.
----                     • {file}: (string)
----                        Path to the file represented by the buffer, relative to the
----                        top-level.
----                     • {toplevel}: (string)
----                        Path to the top-level of the parent git repository.
----                     • {gitdir}: (string)
----                        Path to the git directory of the parent git repository
----                        (typically the ".git/" directory).
----                     • {commit}: (string)
----                        The git revision that the file belongs to.
----                     • {base}: (string|nil)
----                        The git revision that the file should be compared to.
-M.attach = void(function(bufnr, ctx, _trigger)
-   attach_throttled(bufnr or current_buf(), ctx, _trigger)
 end)
 
 local function setup_cli()
-   local funcs = M
    api.nvim_create_user_command('Gitsigns', function(params)
-      require('gitsigns.cli').run(funcs, params)
+      require('gitsigns.cli').run(params)
    end, {
       force = true,
       nargs = '*',
       range = true,
       complete = function(arglead, line)
-         return require('gitsigns.cli').complete(funcs, arglead, line)
+         return require('gitsigns.cli').complete(arglead, line)
       end, })
 end
 
-local function wrap_func(fn, ...)
-   local args = { ... }
-   local nargs = select('#', ...)
-   return function()
-      fn(unpack(args, 1, nargs))
+local exported = {
+   'attach',
+   'actions',
+}
+
+local function setup_debug()
+   log.debug_mode = config.debug_mode
+   log.verbose = config._verbose
+
+   if config.debug_mode then
+      exported[#exported + 1] = 'debug'
    end
 end
 
-local function autocmd(event, opts)
-   local opts0 = {}
-   if type(opts) == "function" then
-      opts0.callback = wrap_func(opts)
-   else
-      opts0 = opts
+local function setup_attach()
+   scheduler()
+
+   -- Attach to all open buffers
+   for _, buf in ipairs(api.nvim_list_bufs()) do
+      if api.nvim_buf_is_loaded(buf) and
+         api.nvim_buf_get_name(buf) ~= '' then
+         M.attach(buf, nil, 'setup')
+         scheduler()
+      end
    end
-   opts0.group = 'gitsigns'
-   api.nvim_create_autocmd(event, opts0)
+
+   api.nvim_create_autocmd({ 'BufRead', 'BufNewFile', 'BufWritePost' }, {
+      group = 'gitsigns',
+      callback = function(data)
+         M.attach(nil, nil, data.event)
+      end,
+   })
 end
 
-local function on_or_after_vimenter(fn)
-   if vim.v.vim_did_enter == 1 then
-      fn()
-   else
-      api.nvim_create_autocmd('VimEnter', {
-         callback = wrap_func(fn),
-         once = true,
-      })
-   end
+local function setup_cwd_head()
+   scheduler()
+   update_cwd_head()
+   -- Need to debounce in case some plugin changes the cwd too often
+   -- (like vim-grepper)
+   api.nvim_create_autocmd('DirChanged', {
+      group = 'gitsigns',
+      callback = function()
+         local debounce = require("gitsigns.debounce").debounce_trailing
+         debounce(100, update_cwd_head)
+      end,
+   })
 end
 
 --- Setup and start Gitsigns.
@@ -417,87 +171,36 @@ M.setup = void(function(cfg)
       print('gitsigns: git not in path. Aborting setup')
       return
    end
+
    if config.yadm.enable and vim.fn.executable('yadm') == 0 then
       print("gitsigns: yadm not in path. Ignoring 'yadm.enable' in config")
       config.yadm.enable = false
       return
    end
 
-   gs_debug.debug_mode = config.debug_mode
-   gs_debug.verbose = config._verbose
-
-   if config.debug_mode then
-      for nm, f in pairs(gs_debug.add_debug_functions(cache)) do
-         (M)[nm] = f
-      end
-   end
-
-   manager.setup()
-
-   Status.formatter = config.status_formatter
-
-   -- Make sure highlights are setup on or after VimEnter so the colorscheme is
-   -- loaded. Do not set them up with vim.schedule as this removes the intro
-   -- message.
-   on_or_after_vimenter(hl.setup_highlights)
-
+   setup_debug()
    setup_cli()
 
-   git.enable_yadm = config.yadm.enable
-   git.set_version(config._git_version)
-   scheduler()
-
-   -- Attach to all open buffers
-   for _, buf in ipairs(api.nvim_list_bufs()) do
-      if api.nvim_buf_is_loaded(buf) and
-         api.nvim_buf_get_name(buf) ~= '' then
-         M.attach(buf, nil, 'setup')
-         scheduler()
-      end
-   end
-
    api.nvim_create_augroup('gitsigns', {})
 
-   autocmd('VimLeavePre', M.detach_all)
-   autocmd('ColorScheme', hl.setup_highlights)
-   autocmd('BufRead', wrap_func(M.attach, nil, nil, 'BufRead'))
-   autocmd('BufNewFile', wrap_func(M.attach, nil, nil, 'BufNewFile'))
-   autocmd('BufWritePost', wrap_func(M.attach, nil, nil, 'BufWritePost'))
-
-   autocmd('OptionSet', {
-      pattern = 'fileformat',
-      callback = function()
-         require('gitsigns.actions').refresh()
-      end, })
-
-
-   -- vimpgrep creates and deletes lots of buffers so attaching to each one will
-   -- waste lots of resource and even slow down vimgrep.
-   autocmd('QuickFixCmdPre', {
-      pattern = '*vimgrep*',
-      callback = function()
-         vimgrep_running = true
-      end,
-   })
-
-   autocmd('QuickFixCmdPost', {
-      pattern = '*vimgrep*',
-      callback = function()
-         vimgrep_running = false
-      end,
-   })
+   if config._test_mode then
+      require('gitsigns.attach')._setup()
+      require('gitsigns.git')._set_version(config._git_version)
+   end
 
-   require('gitsigns.current_line_blame').setup()
+   setup_attach()
+   setup_cwd_head()
 
-   scheduler()
-   manager.update_cwd_head()
-   -- Need to debounce in case some plugin changes the cwd too often
-   -- (like vim-grepper)
-   autocmd('DirChanged', debounce_trailing(100, manager.update_cwd_head))
+   M._setup_done = true
 end)
 
 return setmetatable(M, {
    __index = function(_, f)
-      return (require('gitsigns.actions'))[f]
+      for _, mod in ipairs(exported) do
+         local m = (require)('gitsigns.' .. mod)
+         if m[f] then
+            return m[f]
+         end
+      end
    end,
 })
diff --git a/lua/gitsigns/attach.lua b/lua/gitsigns/attach.lua
new file mode 100644
index 00000000..daa72d91
--- /dev/null
+++ b/lua/gitsigns/attach.lua
@@ -0,0 +1,411 @@
+local async = require('gitsigns.async')
+local git = require('gitsigns.git')
+
+local log = require("gitsigns.debug.log")
+local dprintf = log.dprintf
+local dprint = log.dprint
+
+local manager = require('gitsigns.manager')
+local hl = require('gitsigns.highlight')
+
+local gs_cache = require('gitsigns.cache')
+local cache = gs_cache.cache
+local CacheEntry = gs_cache.CacheEntry
+local Status = require("gitsigns.status")
+
+local gs_config = require('gitsigns.config')
+local config = gs_config.config
+
+local void = require('gitsigns.async').void
+local util = require('gitsigns.util')
+
+local throttle_by_id = require("gitsigns.debounce").throttle_by_id
+
+local api = vim.api
+local uv = vim.loop
+
+
+
+
+
+
+
+
+
+local M = {}
+
+
+
+
+
+local vimgrep_running = false
+
+-- @return (string, string) Tuple of buffer name and commit
+local function parse_fugitive_uri(name)
+   if vim.fn.exists('*FugitiveReal') == 0 then
+      dprint("Fugitive not installed")
+      return
+   end
+
+   local path = vim.fn.FugitiveReal(name)
+   local commit = vim.fn.FugitiveParse(name)[1]:match('([^:]+):.*')
+   if commit == '0' then
+      -- '0' means the index so clear commit so we attach normally
+      commit = nil
+   end
+   return path, commit
+end
+
+local function parse_gitsigns_uri(name)
+   -- TODO(lewis6991): Support submodules
+   local _, _, root_path, commit, rel_path = 
+   name:find([[^gitsigns://(.*)/%.git/(.*):(.*)]])
+   if commit == ':0' then
+      -- ':0' means the index so clear commit so we attach normally
+      commit = nil
+   end
+   if root_path then
+      name = root_path .. '/' .. rel_path
+   end
+   return name, commit
+end
+
+local function get_buf_path(bufnr)
+   local file = 
+   uv.fs_realpath(api.nvim_buf_get_name(bufnr)) or
+
+   api.nvim_buf_call(bufnr, function()
+      return vim.fn.expand('%:p')
+   end)
+
+   if not vim.wo.diff then
+      if vim.startswith(file, 'fugitive://') then
+         local path, commit = parse_fugitive_uri(file)
+         dprintf("Fugitive buffer for file '%s' from path '%s'", path, file)
+         path = uv.fs_realpath(path)
+         if path then
+            return path, commit
+         end
+      end
+
+      if vim.startswith(file, 'gitsigns://') then
+         local path, commit = parse_gitsigns_uri(file)
+         dprintf("Gitsigns buffer for file '%s' from path '%s'", path, file)
+         path = uv.fs_realpath(path)
+         if path then
+            return path, commit
+         end
+      end
+   end
+
+   return file
+end
+
+local function on_lines(_, bufnr, _, first, last_orig, last_new, byte_count)
+   if first == last_orig and last_orig == last_new and byte_count == 0 then
+      -- on_lines can be called twice for undo events; ignore the second
+      -- call which indicates no changes.
+      return
+   end
+   return manager.on_lines(bufnr, first, last_orig, last_new)
+end
+
+local function on_reload(_, bufnr)
+   local __FUNC__ = 'on_reload'
+   dprint('Reload')
+   manager.update_debounced(bufnr)
+end
+
+local function on_detach(_, bufnr)
+   M.detach(bufnr, true)
+end
+
+local function on_attach_pre(bufnr)
+   local gitdir, toplevel
+   if config._on_attach_pre then
+      local res = async.wrap(config._on_attach_pre, 2)(bufnr)
+      dprintf('ran on_attach_pre with result %s', vim.inspect(res))
+      if type(res) == "table" then
+         if type(res.gitdir) == 'string' then
+            gitdir = res.gitdir
+         end
+         if type(res.toplevel) == 'string' then
+            toplevel = res.toplevel
+         end
+      end
+   end
+   return gitdir, toplevel
+end
+
+local function try_worktrees(_bufnr, file, encoding)
+   if not config.worktrees then
+      return
+   end
+
+   for _, wt in ipairs(config.worktrees) do
+      local git_obj = git.Obj.new(file, encoding, wt.gitdir, wt.toplevel)
+      if git_obj and git_obj.object_name then
+         dprintf('Using worktree %s', vim.inspect(wt))
+         return git_obj
+      end
+   end
+end
+
+local done_setup = false
+
+function M._setup()
+   if done_setup then
+      return
+   end
+
+   done_setup = true
+
+   manager.setup()
+
+   hl.setup_highlights()
+   api.nvim_create_autocmd('ColorScheme', {
+      group = 'gitsigns',
+      callback = hl.setup_highlights,
+   })
+
+   api.nvim_create_autocmd('OptionSet', {
+      group = 'gitsigns',
+      pattern = 'fileformat',
+      callback = function()
+         require('gitsigns.actions').refresh()
+      end, })
+
+
+   -- vimpgrep creates and deletes lots of buffers so attaching to each one will
+   -- waste lots of resource and even slow down vimgrep.
+   api.nvim_create_autocmd('QuickFixCmdPre', {
+      group = 'gitsigns',
+      pattern = '*vimgrep*',
+      callback = function()
+         vimgrep_running = true
+      end,
+   })
+
+   api.nvim_create_autocmd('QuickFixCmdPost', {
+      group = 'gitsigns',
+      pattern = '*vimgrep*',
+      callback = function()
+         vimgrep_running = false
+      end,
+   })
+
+   require('gitsigns.current_line_blame').setup()
+
+   api.nvim_create_autocmd('VimLeavePre', {
+      group = 'gitsigns',
+      callback = M.detach_all,
+   })
+
+end
+
+-- Ensure attaches cannot be interleaved.
+-- Since attaches are asynchronous we need to make sure an attach isn't
+-- performed whilst another one is in progress.
+local attach_throttled = throttle_by_id(function(cbuf, ctx, aucmd)
+   local __FUNC__ = 'attach'
+
+   M._setup()
+
+   if vimgrep_running then
+      dprint('attaching is disabled')
+      return
+   end
+
+   if cache[cbuf] then
+      dprint('Already attached')
+      return
+   end
+
+   if aucmd then
+      dprintf('Attaching (trigger=%s)', aucmd)
+   else
+      dprint('Attaching')
+   end
+
+   if not api.nvim_buf_is_loaded(cbuf) then
+      dprint('Non-loaded buffer')
+      return
+   end
+
+   local encoding = vim.bo[cbuf].fileencoding
+   if encoding == '' then
+      encoding = 'utf-8'
+   end
+   local file
+   local commit
+   local gitdir_oap
+   local toplevel_oap
+
+   if ctx then
+      gitdir_oap = ctx.gitdir
+      toplevel_oap = ctx.toplevel
+      file = ctx.toplevel .. util.path_sep .. ctx.file
+      commit = ctx.commit
+   else
+      if api.nvim_buf_line_count(cbuf) > config.max_file_length then
+         dprint('Exceeds max_file_length')
+         return
+      end
+
+      if vim.bo[cbuf].buftype ~= '' then
+         dprint('Non-normal buffer')
+         return
+      end
+
+      file, commit = get_buf_path(cbuf)
+      local file_dir = util.dirname(file)
+
+      if not file_dir or not util.path_exists(file_dir) then
+         dprint('Not a path')
+         return
+      end
+
+      gitdir_oap, toplevel_oap = on_attach_pre(cbuf)
+   end
+
+   local git_obj = git.Obj.new(file, encoding, gitdir_oap, toplevel_oap)
+
+   if not git_obj and not ctx then
+      git_obj = try_worktrees(cbuf, file, encoding)
+      async.scheduler()
+   end
+
+   if not git_obj then
+      dprint('Empty git obj')
+      return
+   end
+   local repo = git_obj.repo
+
+   async.scheduler()
+   Status:update(cbuf, {
+      head = repo.abbrev_head,
+      root = repo.toplevel,
+      gitdir = repo.gitdir,
+   })
+
+   if vim.startswith(file, repo.gitdir .. util.path_sep) then
+      dprint('In non-standard git dir')
+      return
+   end
+
+   if not ctx and (not util.path_exists(file) or uv.fs_stat(file).type == 'directory') then
+      dprint('Not a file')
+      return
+   end
+
+   if not git_obj.relpath then
+      dprint('Cannot resolve file in repo')
+      return
+   end
+
+   if not config.attach_to_untracked and git_obj.object_name == nil then
+      dprint('File is untracked')
+      return
+   end
+
+   -- On windows os.tmpname() crashes in callback threads so initialise this
+   -- variable on the main thread.
+   async.scheduler()
+
+   if config.on_attach and config.on_attach(cbuf) == false then
+      dprint('User on_attach() returned false')
+      return
+   end
+
+   cache[cbuf] = CacheEntry.new({
+      base = ctx and ctx.base or config.base,
+      file = file,
+      commit = commit,
+      gitdir_watcher = manager.watch_gitdir(cbuf, repo.gitdir),
+      git_obj = git_obj,
+   })
+
+   if not api.nvim_buf_is_loaded(cbuf) then
+      dprint('Un-loaded buffer')
+      return
+   end
+
+   -- Make sure to attach before the first update (which is async) so we pick up
+   -- changes from BufReadCmd.
+   api.nvim_buf_attach(cbuf, false, {
+      on_lines = on_lines,
+      on_reload = on_reload,
+      on_detach = on_detach,
+   })
+
+   -- Initial update
+   manager.update(cbuf, cache[cbuf])
+
+   if config.keymaps and not vim.tbl_isempty(config.keymaps) then
+      require('gitsigns.mappings')(config.keymaps, cbuf)
+   end
+end)
+
+--- Detach Gitsigns from all buffers it is attached to.
+function M.detach_all()
+   for k, _ in pairs(cache) do
+      M.detach(k)
+   end
+end
+
+--- Detach Gitsigns from the buffer {bufnr}. If {bufnr} is not
+--- provided then the current buffer is used.
+---
+--- Parameters: ~
+---       {bufnr}   (number): Buffer number
+function M.detach(bufnr, _keep_signs)
+   -- When this is called interactively (with no arguments) we want to remove all
+   -- the signs, however if called via a detach event (due to nvim_buf_attach)
+   -- then we don't want to clear the signs in case the buffer is just being
+   -- updated due to the file externally changing. When this happens a detach and
+   -- attach event happen in sequence and so we keep the old signs to stop the
+   -- sign column width moving about between updates.
+   bufnr = bufnr or api.nvim_get_current_buf()
+   dprint('Detached')
+   local bcache = cache[bufnr]
+   if not bcache then
+      dprint('Cache was nil')
+      return
+   end
+
+   manager.detach(bufnr, _keep_signs)
+
+   -- Clear status variables
+   Status:clear(bufnr)
+
+   cache:destroy(bufnr)
+end
+
+
+--- Attach Gitsigns to the buffer.
+---
+--- Attributes: ~
+---       {async}
+---
+--- Parameters: ~
+---       {bufnr}   (number): Buffer number
+---       {ctx}      (table|nil):
+---                     Git context data that may optionally be used to attach to any
+---                     buffer that represents a real git object.
+---                     • {file}: (string)
+---                        Path to the file represented by the buffer, relative to the
+---                        top-level.
+---                     • {toplevel}: (string)
+---                        Path to the top-level of the parent git repository.
+---                     • {gitdir}: (string)
+---                        Path to the git directory of the parent git repository
+---                        (typically the ".git/" directory).
+---                     • {commit}: (string)
+---                        The git revision that the file belongs to.
+---                     • {base}: (string|nil)
+---                        The git revision that the file should be compared to.
+M.attach = void(function(bufnr, ctx, _trigger)
+   attach_throttled(bufnr or api.nvim_get_current_buf(), ctx, _trigger)
+end)
+
+return M
diff --git a/lua/gitsigns/cli.lua b/lua/gitsigns/cli.lua
index 6e1f1158..c3675932 100644
--- a/lua/gitsigns/cli.lua
+++ b/lua/gitsigns/cli.lua
@@ -1,12 +1,22 @@
 local async = require('gitsigns.async')
 local void = require('gitsigns.async').void
 
-local gs_debug = require("gitsigns.debug")
-local dprintf = gs_debug.dprintf
+local log = require('gitsigns.debug.log')
+local dprintf = log.dprintf
 local message = require('gitsigns.message')
 
 local parse_args = require('gitsigns.cli.argparse').parse_args
 
+local actions = require('gitsigns.actions')
+local attach = require('gitsigns.attach')
+local gs_debug = require('gitsigns.debug')
+
+local sources = {
+   [actions] = true,
+   [attach] = false,
+   [gs_debug] = false,
+}
+
 -- try to parse each argument as a lua boolean, nil or number, if fails then
 -- keep argument as a string:
 --
@@ -29,14 +39,13 @@ local M = {}
 
 
 
-function M.complete(funcs, arglead, line)
+function M.complete(arglead, line)
    local words = vim.split(line, '%s+')
    local n = #words
 
-   local actions = require('gitsigns.actions')
    local matches = {}
    if n == 2 then
-      for _, m in ipairs({ actions, funcs }) do
+      for m, _ in pairs(sources) do
          for func, _ in pairs(m) do
             if not func:match('^[a-z]') then
                -- exclude
@@ -55,22 +64,20 @@ function M.complete(funcs, arglead, line)
    return matches
 end
 
-M.run = void(function(funcs, params)
+M.run = void(function(params)
+   local __FUNC__ = 'cli.run'
    local pos_args_raw, named_args_raw = parse_args(params.args)
 
    local func = pos_args_raw[1]
 
    if not func then
-      func = async.wrap(vim.ui.select, 3)(M.complete(funcs, '', 'Gitsigns '), {})
+      func = async.wrap(vim.ui.select, 3)(M.complete('', 'Gitsigns '), {})
    end
 
    local pos_args = vim.tbl_map(parse_to_lua, vim.list_slice(pos_args_raw, 2))
    local named_args = vim.tbl_map(parse_to_lua, named_args_raw)
    local args = vim.tbl_extend('error', pos_args, named_args)
 
-   local actions = require('gitsigns.actions')
-   local actions0 = actions
-
    dprintf("Running action '%s' with arguments %s", func, vim.inspect(args, { newline = ' ', indent = '' }))
 
    local cmd_func = actions._get_cmd_func(func)
@@ -81,15 +88,13 @@ M.run = void(function(funcs, params)
       return
    end
 
-   if type(actions0[func]) == 'function' then
-      actions0[func](unpack(pos_args), named_args)
-      return
-   end
-
-   if type(funcs[func]) == 'function' then
-      -- Note functions here do not have named arguments
-      funcs[func](unpack(pos_args))
-      return
+   for m, has_named in pairs(sources) do
+      local f = (m)[func]
+      if type(f) == "function" then
+         -- Note functions here do not have named arguments
+         f(unpack(pos_args), has_named and named_args or nil)
+         return
+      end
    end
 
    message.error('%s is not a valid function or action', func)
diff --git a/lua/gitsigns/config.lua b/lua/gitsigns/config.lua
index 30de8ba9..c35c32cf 100644
--- a/lua/gitsigns/config.lua
+++ b/lua/gitsigns/config.lua
@@ -135,6 +135,7 @@ local M = {Config = {DiffOpts = {}, SignConfig = {}, watch_gitdir = {}, current_
 
 
 
+
 M.config = {}
 
 M.schema = {
@@ -712,6 +713,11 @@ M.schema = {
     ]],
    },
 
+   _test_mode = {
+      type = 'boolean',
+      default = false,
+   },
+
    word_diff = {
       type = 'boolean',
       default = false,
diff --git a/lua/gitsigns/debug.lua b/lua/gitsigns/debug.lua
index 6696b98a..fb8b497d 100644
--- a/lua/gitsigns/debug.lua
+++ b/lua/gitsigns/debug.lua
@@ -1,110 +1,6 @@
-local M = {
-   debug_mode = false,
-   verbose = false,
-   messages = {},
-}
+local log = require('gitsigns.debug.log')
 
-local function getvarvalue(name, lvl)
-   lvl = lvl + 1
-   local value
-   local found
-
-   -- try local variables
-   local i = 1
-   while true do
-      local n, v = debug.getlocal(lvl, i)
-      if not n then break end
-      if n == name then
-         value = v
-         found = true
-      end
-      i = i + 1
-   end
-   if found then return value end
-
-   -- try upvalues
-   local func = debug.getinfo(lvl).func
-   i = 1
-   while true do
-      local n, v = debug.getupvalue(func, i)
-      if not n then break end
-      if n == name then return v end
-      i = i + 1
-   end
-
-   -- not found; get global
-   return getfenv(func)[name]
-end
-
-local function get_context(lvl)
-   lvl = lvl + 1
-   local ret = {}
-   ret.name = getvarvalue('__FUNC__', lvl)
-   if not ret.name then
-      local name0 = debug.getinfo(lvl, 'n').name or ''
-      ret.name = name0:gsub('(.*)%d+$', '%1')
-   end
-   ret.bufnr = getvarvalue('bufnr', lvl) or
-   getvarvalue('_bufnr', lvl) or
-   getvarvalue('cbuf', lvl) or
-   getvarvalue('buf', lvl)
-
-   return ret
-end
-
--- If called in a callback then make sure the callback defines a __FUNC__
--- variable which can be used to identify the name of the function.
-local function cprint(obj, lvl)
-   lvl = lvl + 1
-   local msg = type(obj) == "string" and obj or vim.inspect(obj)
-   local ctx = get_context(lvl)
-   local msg2
-   if ctx.bufnr then
-      msg2 = string.format('%s(%s): %s', ctx.name, ctx.bufnr, msg)
-   else
-      msg2 = string.format('%s: %s', ctx.name, msg)
-   end
-   table.insert(M.messages, msg2)
-end
-
-function M.dprint(obj)
-   if not M.debug_mode then return end
-   cprint(obj, 2)
-end
-
-function M.dprintf(obj, ...)
-   if not M.debug_mode then return end
-   cprint(obj:format(...), 2)
-end
-
-function M.vprint(obj)
-   if not (M.debug_mode and M.verbose) then return end
-   cprint(obj, 2)
-end
-
-function M.vprintf(obj, ...)
-   if not (M.debug_mode and M.verbose) then return end
-   cprint(obj:format(...), 2)
-end
-
-local function eprint(msg, level)
-   local info = debug.getinfo(level + 2, 'Sl')
-   if info then
-      msg = string.format('(ERROR) %s(%d): %s', info.short_src, info.currentline, msg)
-   end
-   M.messages[#M.messages + 1] = msg
-   if M.debug_mode then
-      error(msg)
-   end
-end
-
-function M.eprint(msg)
-   eprint(msg, 1)
-end
-
-function M.eprintf(fmt, ...)
-   eprint(fmt:format(...), 1)
-end
+local M = {}
 
 local function process(raw_item, path)
    if path[#path] == vim.inspect.METATABLE then
@@ -123,28 +19,25 @@ local function process(raw_item, path)
    return raw_item
 end
 
-function M.add_debug_functions(cache)
-   local R = {}
-   R.dump_cache = function()
-      local text = vim.inspect(cache, { process = process })
-      vim.api.nvim_echo({ { text } }, false, {})
-      return cache
-   end
+function M.dump_cache()
+   -- TODO(lewis6991): hack: use package.loaded to avoid circular deps
+   local cache = (package.loaded['gitsigns.cache']).cache
+   local text = vim.inspect(cache, { process = process })
+   vim.api.nvim_echo({ { text } }, false, {})
+   return cache
+end
 
-   R.debug_messages = function(noecho)
-      if not noecho then
-         for _, m in ipairs(M.messages) do
-            vim.api.nvim_echo({ { m } }, false, {})
-         end
+function M.debug_messages(noecho)
+   if not noecho then
+      for _, m in ipairs(log.messages) do
+         vim.api.nvim_echo({ { m } }, false, {})
       end
-      return M.messages
-   end
-
-   R.clear_debug = function()
-      M.messages = {}
    end
+   return log.messages
+end
 
-   return R
+function M.clear_debug()
+   log.messages = {}
 end
 
 return M
diff --git a/lua/gitsigns/debug/log.lua b/lua/gitsigns/debug/log.lua
new file mode 100644
index 00000000..3ca2246b
--- /dev/null
+++ b/lua/gitsigns/debug/log.lua
@@ -0,0 +1,109 @@
+local M = {
+   debug_mode = false,
+   verbose = false,
+   messages = {},
+}
+
+local function getvarvalue(name, lvl)
+   lvl = lvl + 1
+   local value
+   local found
+
+   -- try local variables
+   local i = 1
+   while true do
+      local n, v = debug.getlocal(lvl, i)
+      if not n then break end
+      if n == name then
+         value = v
+         found = true
+      end
+      i = i + 1
+   end
+   if found then return value end
+
+   -- try upvalues
+   local func = debug.getinfo(lvl).func
+   i = 1
+   while true do
+      local n, v = debug.getupvalue(func, i)
+      if not n then break end
+      if n == name then return v end
+      i = i + 1
+   end
+
+   -- not found; get global
+   return getfenv(func)[name]
+end
+
+local function get_context(lvl)
+   lvl = lvl + 1
+   local ret = {}
+   ret.name = getvarvalue('__FUNC__', lvl)
+   if not ret.name then
+      local name0 = debug.getinfo(lvl, 'n').name or ''
+      ret.name = name0:gsub('(.*)%d+$', '%1')
+   end
+   ret.bufnr = getvarvalue('bufnr', lvl) or
+   getvarvalue('_bufnr', lvl) or
+   getvarvalue('cbuf', lvl) or
+   getvarvalue('buf', lvl)
+
+   return ret
+end
+
+-- If called in a callback then make sure the callback defines a __FUNC__
+-- variable which can be used to identify the name of the function.
+local function cprint(obj, lvl)
+   lvl = lvl + 1
+   local msg = type(obj) == "string" and obj or vim.inspect(obj)
+   local ctx = get_context(lvl)
+   local msg2
+   if ctx.bufnr then
+      msg2 = string.format('%s(%s): %s', ctx.name, ctx.bufnr, msg)
+   else
+      msg2 = string.format('%s: %s', ctx.name, msg)
+   end
+   table.insert(M.messages, msg2)
+end
+
+function M.dprint(obj)
+   if not M.debug_mode then return end
+   cprint(obj, 2)
+end
+
+function M.dprintf(obj, ...)
+   if not M.debug_mode then return end
+   cprint(obj:format(...), 2)
+end
+
+function M.vprint(obj)
+   if not (M.debug_mode and M.verbose) then return end
+   cprint(obj, 2)
+end
+
+function M.vprintf(obj, ...)
+   if not (M.debug_mode and M.verbose) then return end
+   cprint(obj:format(...), 2)
+end
+
+local function eprint(msg, level)
+   local info = debug.getinfo(level + 2, 'Sl')
+   if info then
+      msg = string.format('(ERROR) %s(%d): %s', info.short_src, info.currentline, msg)
+   end
+   M.messages[#M.messages + 1] = msg
+   if M.debug_mode then
+      error(msg)
+   end
+end
+
+function M.eprint(msg)
+   eprint(msg, 1)
+end
+
+function M.eprintf(fmt, ...)
+   eprint(fmt:format(...), 1)
+end
+
+return M
diff --git a/lua/gitsigns/git.lua b/lua/gitsigns/git.lua
index 422939e7..3cfb8d3d 100644
--- a/lua/gitsigns/git.lua
+++ b/lua/gitsigns/git.lua
@@ -1,18 +1,21 @@
 local async = require('gitsigns.async')
 local scheduler = require('gitsigns.async').scheduler
 
-local gsd = require("gitsigns.debug")
+local log = require("gitsigns.debug.log")
 local util = require('gitsigns.util')
 local subprocess = require('gitsigns.subprocess')
 
+local gs_config = require('gitsigns.config')
+local config = gs_config.config
+
 local gs_hunks = require("gitsigns.hunks")
 local Hunk = gs_hunks.Hunk
 
 local uv = vim.loop
 local startswith = vim.startswith
 
-local dprint = require("gitsigns.debug").dprint
-local eprint = require("gitsigns.debug").eprint
+local dprint = require('gitsigns.debug.log').dprint
+local eprint = require('gitsigns.debug.log').eprint
 local err = require('gitsigns.message').error
 
 
@@ -78,10 +81,6 @@ local M = {BlameInfo = {}, Version = {}, RepoInfo = {}, Repo = {}, FileProps = {
 
 
 
-
-
-
-
 
 
 
@@ -167,8 +166,35 @@ local function check_version(version)
    return true
 end
 
+--- @async
+function M._set_version(version)
+   if version ~= 'auto' then
+      M.version = parse_version(version)
+      return
+   end
+
+   local _, _, stdout, stderr = async.wait(2, subprocess.run_job, {
+      command = 'git', args = { '--version' },
+   })
+
+   local line = vim.split(stdout or '', '\n', true)[1]
+   if not line then
+      err("Unable to detect git version as 'git --version' failed to return anything")
+      eprint(stderr)
+      return
+   end
+   assert(type(line) == 'string', 'Unexpected output: ' .. line)
+   assert(startswith(line, 'git version'), 'Unexpected output: ' .. line)
+   local parts = vim.split(line, '%s+')
+   M.version = parse_version(parts[3])
+end
+
+
 --- @async
 local git_command = async.create(function(args, spec)
+   if not M.version then
+      M._set_version(config._git_version)
+   end
    spec = spec or {}
    spec.command = spec.command or 'git'
    spec.args = spec.command == 'git' and {
@@ -187,7 +213,7 @@ local git_command = async.create(function(args, spec)
    if not spec.suppress_stderr then
       if stderr then
          local cmd_str = table.concat({ spec.command, unpack(args) }, ' ')
-         gsd.eprintf("Recieved stderr when running command\n'%s':\n%s", cmd_str, stderr)
+         log.eprintf("Recieved stderr when running command\n'%s':\n%s", cmd_str, stderr)
       end
    end
 
@@ -199,10 +225,10 @@ local git_command = async.create(function(args, spec)
       stdout_lines[#stdout_lines] = nil
    end
 
-   if gsd.verbose then
-      gsd.vprintf('%d lines:', #stdout_lines)
+   if log.verbose then
+      log.vprintf('%d lines:', #stdout_lines)
       for i = 1, math.min(10, #stdout_lines) do
-         gsd.vprintf('\t%s', stdout_lines[i])
+         log.vprintf('\t%s', stdout_lines[i])
       end
    end
 
@@ -235,7 +261,7 @@ local function process_abbrev_head(gitdir, head_str, path, cmd)
          suppress_stderr = true,
          cwd = path,
       })[1] or ''
-      if gsd.debug_mode and short_sha ~= '' then
+      if log.debug_mode and short_sha ~= '' then
          short_sha = 'HEAD'
       end
       if util.path_exists(gitdir .. '/rebase-merge') or
@@ -310,25 +336,6 @@ function M.get_repo_info(path, cmd, gitdir, toplevel)
    return ret
 end
 
---- @async
-function M.set_version(version)
-   if version ~= 'auto' then
-      M.version = parse_version(version)
-      return
-   end
-   local results, stderr = git_command({ '--version' })
-   local line = results[1]
-   if not line then
-      err("Unable to detect git version as 'git --version' failed to return anything")
-      eprint(stderr)
-      return
-   end
-   assert(type(line) == 'string', 'Unexpected output: ' .. line)
-   assert(startswith(line, 'git version'), 'Unexpected output: ' .. line)
-   local parts = vim.split(line, '%s+')
-   M.version = parse_version(parts[3])
-end
-
 --------------------------------------------------------------------------------
 -- Git repo object methods
 --------------------------------------------------------------------------------
@@ -444,7 +451,7 @@ function Repo.new(dir, gitdir, toplevel)
    end
 
    -- Try yadm
-   if M.enable_yadm and not self.gitdir then
+   if config.yadm.enable and not self.gitdir then
       if vim.startswith(dir, os.getenv('HOME')) and
          #git_command({ 'ls-files', dir }, { command = 'yadm' }) ~= 0 then
          M.get_repo_info(dir, 'yadm', gitdir, toplevel)
@@ -501,7 +508,7 @@ function Obj:file_info(file, silent)
       -- Suppress_stderr for the cases when we run:
       --    git ls-files --others exists/nonexist
       if not stderr:match('^warning: could not open directory .*: No such file or directory') then
-         gsd.eprint(stderr)
+         log.eprint(stderr)
       end
    end
 
diff --git a/lua/gitsigns/highlight.lua b/lua/gitsigns/highlight.lua
index 4fc134ba..e4193224 100644
--- a/lua/gitsigns/highlight.lua
+++ b/lua/gitsigns/highlight.lua
@@ -168,8 +168,11 @@ local function cmul(x, factor)
    return math.floor(math.floor(r * factor) * 2 ^ 16 + math.floor(g * factor) * 2 ^ 8 + math.floor(b * factor))
 end
 
+local function dprintf(fmt, ...)
+   require('gitsigns.debug.log').dprintf(fmt, ...)
+end
+
 local function derive(hl, hldef)
-   local dprintf = require("gitsigns.debug").dprintf
    for _, d in ipairs(hldef) do
       if is_hl_set(d) then
          dprintf('Deriving %s from %s', hl, d)
@@ -201,7 +204,6 @@ end
 -- Setup a GitSign* highlight by deriving it from other potentially present
 -- highlights.
 M.setup_highlights = function()
-   local dprintf = require("gitsigns.debug").dprintf
    for _, hlg in ipairs(M.hls) do
       for hl, hldef in pairs(hlg) do
          if is_hl_set(hl) then
diff --git a/lua/gitsigns/manager.lua b/lua/gitsigns/manager.lua
index 891e4a78..6d7df375 100644
--- a/lua/gitsigns/manager.lua
+++ b/lua/gitsigns/manager.lua
@@ -12,15 +12,14 @@ local Status = require("gitsigns.status")
 local debounce_trailing = require('gitsigns.debounce').debounce_trailing
 local throttle_by_id = require('gitsigns.debounce').throttle_by_id
 
-local gs_debug = require("gitsigns.debug")
-local dprint = gs_debug.dprint
-local dprintf = gs_debug.dprintf
-local eprint = gs_debug.eprint
+local log = require('gitsigns.debug.log')
+local dprint = log.dprint
+local dprintf = log.dprintf
+local eprint = log.eprint
 
 local subprocess = require('gitsigns.subprocess')
 local util = require('gitsigns.util')
 local run_diff = require('gitsigns.diff')
-local git = require('gitsigns.git')
 local uv = require('gitsigns.uv')
 
 local gs_hunks = require("gitsigns.hunks")
@@ -43,7 +42,6 @@ local M = {}
 
 
 
-
 local scheduler_if_buf_valid = awrap(function(buf, cb)
    vim.schedule(function()
       if vim.api.nvim_buf_is_valid(buf) then
@@ -444,67 +442,6 @@ function M.watch_gitdir(bufnr, gitdir)
    return w
 end
 
-local cwd_watcher
-
-M.update_cwd_head = void(function()
-   if cwd_watcher then
-      cwd_watcher:stop()
-   else
-      cwd_watcher = uv.new_fs_poll(true)
-   end
-
-   local cwd = vim.loop.cwd()
-   local gitdir, head
-
-   -- Look in the cache first
-   for _, bcache in pairs(cache) do
-      local repo = bcache.git_obj.repo
-      if repo.toplevel == cwd then
-         head = repo.abbrev_head
-         gitdir = repo.gitdir
-         break
-      end
-   end
-
-   if not head or not gitdir then
-      local info = git.get_repo_info(cwd)
-      gitdir = info.gitdir
-      head = info.abbrev_head
-   end
-
-   scheduler()
-   vim.g.gitsigns_head = head
-
-   if not gitdir then
-      return
-   end
-
-   local towatch = gitdir .. '/HEAD'
-
-   if cwd_watcher:getpath() == towatch then
-      -- Already watching
-      return
-   end
-
-   -- Watch .git/HEAD to detect branch changes
-   cwd_watcher:start(
-   towatch,
-   config.watch_gitdir.interval,
-   void(function(err)
-      local __FUNC__ = 'cwd_watcher_cb'
-      if err then
-         dprintf('Git dir update error: %s', err)
-         return
-      end
-      dprint('Git cwd dir update')
-
-      local new_head = git.get_repo_info(cwd).abbrev_head
-      scheduler()
-      vim.g.gitsigns_head = new_head
-   end))
-
-end)
-
 function M.reset_signs()
    -- Remove all signs
    signs_normal:reset()
diff --git a/lua/gitsigns/signs.lua b/lua/gitsigns/signs.lua
index 922bfc15..92ae0dfc 100644
--- a/lua/gitsigns/signs.lua
+++ b/lua/gitsigns/signs.lua
@@ -1,7 +1,7 @@
 local config = require('gitsigns.config').config
 local SignsConfig = require('gitsigns.config').Config.SignsConfig
 
-local dprint = require('gitsigns.debug').dprint
+local dprint = require('gitsigns.debug.log').dprint
 
 local B = require('gitsigns.signs.base')
 
diff --git a/lua/gitsigns/status.lua b/lua/gitsigns/status.lua
index f4f43de9..d4e92fb8 100644
--- a/lua/gitsigns/status.lua
+++ b/lua/gitsigns/status.lua
@@ -1,5 +1,6 @@
 local api = vim.api
 
+
 local StatusObj = {}
 
 
@@ -11,7 +12,6 @@ local StatusObj = {}
 
 local Status = {
    StatusObj = StatusObj,
-   formatter = nil,
 }
 
 function Status:update(bufnr, status)
@@ -24,7 +24,10 @@ function Status:update(bufnr, status)
    end
    vim.b[bufnr].gitsigns_head = status.head or ''
    vim.b[bufnr].gitsigns_status_dict = status
-   vim.b[bufnr].gitsigns_status = self.formatter(status)
+
+   local config = require('gitsigns.config').config
+
+   vim.b[bufnr].gitsigns_status = config.status_formatter(status)
 end
 
 function Status:clear(bufnr)
diff --git a/lua/gitsigns/subprocess.lua b/lua/gitsigns/subprocess.lua
index 6b3b94b8..26594e5d 100644
--- a/lua/gitsigns/subprocess.lua
+++ b/lua/gitsigns/subprocess.lua
@@ -1,4 +1,4 @@
-local gsd = require("gitsigns.debug")
+local log = require("gitsigns.debug.log")
 local guv = require("gitsigns.uv")
 local uv = vim.loop
 
@@ -47,7 +47,7 @@ end
 local function handle_reader(pipe, output)
    pipe:read_start(function(err, data)
       if err then
-         gsd.eprint(err)
+         log.eprint(err)
       end
       if data then
          output[#output + 1] = data
@@ -59,9 +59,9 @@ end
 
 function M.run_job(obj, callback)
    local __FUNC__ = 'run_job'
-   if gsd.debug_mode then
+   if log.debug_mode then
       local cmd = obj.command .. ' ' .. table.concat(obj.args, ' ')
-      gsd.dprint(cmd)
+      log.dprint(cmd)
    end
 
    local stdout_data = {}
@@ -75,7 +75,7 @@ function M.run_job(obj, callback)
    end
 
    local handle, pid
-   handle, pid = guv.spawn(obj.command, {
+   handle, pid = vim.loop.spawn(obj.command, {
       args = obj.args,
       stdio = { stdin, stdout, stderr },
       cwd = obj.cwd,
diff --git a/teal/gitsigns.tl b/teal/gitsigns.tl
index 34dc067e..29fabebf 100644
--- a/teal/gitsigns.tl
+++ b/teal/gitsigns.tl
@@ -1,405 +1,159 @@
-local async = require('gitsigns.async')
 local void = require('gitsigns.async').void
 local scheduler = require('gitsigns.async').scheduler
 
-local Status     = require("gitsigns.status")
-local git        = require('gitsigns.git')
-local manager    = require('gitsigns.manager')
-local util       = require('gitsigns.util')
-local hl         = require('gitsigns.highlight')
-
-local gs_cache   = require('gitsigns.cache')
-local cache      = gs_cache.cache
-local CacheEntry = gs_cache.CacheEntry
-
 local gs_config  = require('gitsigns.config')
 local Config     = gs_config.Config
 local config     = gs_config.config
 
-local gs_debug   = require("gitsigns.debug")
-local dprintf    = gs_debug.dprintf
-local dprint     = gs_debug.dprint
-
-local Debounce          = require("gitsigns.debounce")
-local debounce_trailing = Debounce.debounce_trailing
-local throttle_by_id    = Debounce.throttle_by_id
+local log      = require('gitsigns.debug.log')
+local dprintf  = log.dprintf
+local dprint   = log.dprint
 
 local api = vim.api
-local uv = vim.loop
-local current_buf = api.nvim_get_current_buf
+local uv  = require('gitsigns.uv')
 
 local record M
-  setup      : function(cfg: Config)
-  detach     : function(bufnr: integer, _keep_signs: boolean)
-  detach_all : function()
-  attach     : function(cbuf: integer, ctx: GitContext, trigger: string)
-
-  record GitContext
-    toplevel: string
-    gitdir: string
-    file: string
-    commit: string
-    base: string
-  end
-end
+  setup: function(cfg: Config)
 
-local GitContext = M.GitContext
+  -- from attach.tl
+  attach: function(cbuf: integer, ctx: table, trigger: string)
 
---- Detach Gitsigns from all buffers it is attached to.
-function M.detach_all()
-  for k, _ in pairs(cache as {integer:CacheEntry}) do
-    M.detach(k)
-  end
+  _setup_done: boolean
 end
 
---- Detach Gitsigns from the buffer {bufnr}. If {bufnr} is not
---- provided then the current buffer is used.
----
---- Parameters: ~
----     {bufnr}  (number): Buffer number
-function M.detach(bufnr: integer, _keep_signs: boolean)
-  -- When this is called interactively (with no arguments) we want to remove all
-  -- the signs, however if called via a detach event (due to nvim_buf_attach)
-  -- then we don't want to clear the signs in case the buffer is just being
-  -- updated due to the file externally changing. When this happens a detach and
-  -- attach event happen in sequence and so we keep the old signs to stop the
-  -- sign column width moving about between updates.
-  bufnr = bufnr or current_buf()
-  dprint('Detached')
-  local bcache = cache[bufnr]
-  if not bcache then
-    dprint('Cache was nil')
-    return
-  end
-
-  manager.detach(bufnr, _keep_signs)
+local cwd_watcher: vim.loop.FSPollObj
 
-  -- Clear status variables
-  Status:clear(bufnr)
-
-  cache:destroy(bufnr)
-end
-
--- @return (string, string) Tuple of buffer name and commit
-local function parse_fugitive_uri(name: string): string, string
-  if vim.fn.exists('*FugitiveReal') == 0 then
-    dprint("Fugitive not installed")
-    return
-  end
-
-  local path = vim.fn.FugitiveReal(name)
-  local commit = vim.fn.FugitiveParse(name)[1]:match('([^:]+):.*')
-  if commit == '0' then
-    -- '0' means the index so clear commit so we attach normally
-    commit = nil
-  end
-  return path, commit
-end
-
-local function parse_gitsigns_uri(name: string): string, string
-  -- TODO(lewis6991): Support submodules
-  local _, _, root_path, commit, rel_path =
-    name:find([[^gitsigns://(.*)/%.git/(.*):(.*)]])
-  if commit == ':0' then
-    -- ':0' means the index so clear commit so we attach normally
-    commit = nil
-  end
-  if root_path then
-    name = root_path .. '/' .. rel_path
-  end
-  return name, commit
-end
-
-local function get_buf_path(bufnr: integer): string, string
-  local file =
-    uv.fs_realpath(api.nvim_buf_get_name(bufnr))
-      or
-    api.nvim_buf_call(bufnr, function(): string
-      return vim.fn.expand('%:p')
-    end)
-
-  if not vim.wo.diff then
-    if vim.startswith(file, 'fugitive://') then
-      local path, commit = parse_fugitive_uri(file)
-      dprintf("Fugitive buffer for file '%s' from path '%s'", path, file)
-      path = uv.fs_realpath(path)
-      if path then
-        return path, commit
-      end
-    end
-
-    if vim.startswith(file, 'gitsigns://') then
-      local path, commit = parse_gitsigns_uri(file)
-      dprintf("Gitsigns buffer for file '%s' from path '%s'", path, file)
-      path = uv.fs_realpath(path)
-      if path then
-        return path, commit
-      end
-    end
-  end
-
-  return file
-end
-
-local vimgrep_running = false
-
-local function on_lines(_, bufnr: integer, _, first: integer, last_orig: integer, last_new: integer, byte_count: integer): boolean
-  if first == last_orig and last_orig == last_new and byte_count == 0 then
-    -- on_lines can be called twice for undo events; ignore the second
-    -- call which indicates no changes.
-    return
-  end
-  return manager.on_lines(bufnr, first, last_orig, last_new)
-end
-
-local function on_reload(_, bufnr: integer)
-  local __FUNC__ = 'on_reload'
-  dprint('Reload')
-  manager.update_debounced(bufnr)
-end
-
-local function on_detach(_, bufnr: integer)
-  M.detach(bufnr, true)
-end
-
-local function on_attach_pre(bufnr: integer): string, string
-  local gitdir, toplevel: string, string
-  if config._on_attach_pre then
-    local res: any = async.wrap(config._on_attach_pre, 2)(bufnr)
-    dprintf('ran on_attach_pre with result %s', vim.inspect(res))
-    if res is table then
-      if type(res.gitdir) == 'string' then
-        gitdir = res.gitdir as string
-      end
-      if type(res.toplevel) == 'string' then
-        toplevel = res.toplevel as string
-      end
-    end
-  end
-  return gitdir, toplevel
-end
-
-local function try_worktrees(_bufnr: integer, file: string, encoding: string): git.Obj
-  if not config.worktrees then
-    return
-  end
-
-  for _, wt in ipairs(config.worktrees) do
-    local git_obj = git.Obj.new(file, encoding, wt.gitdir, wt.toplevel)
-    if git_obj and git_obj.object_name then
-      dprintf('Using worktree %s', vim.inspect(wt))
-      return git_obj
-    end
-  end
-end
-
--- Ensure attaches cannot be interleaved.
--- Since attaches are asynchronous we need to make sure an attach isn't
--- performed whilst another one is in progress.
-local attach_throttled = throttle_by_id(function(cbuf: integer, ctx: GitContext, aucmd: string)
-  local __FUNC__ = 'attach'
-  if vimgrep_running then
-    dprint('attaching is disabled')
-    return
-  end
+local update_cwd_head = void(function()
+  local paths = vim.fs.find('.git', {
+    limit = 1,
+    upward = true,
+    type = 'directory'
+  })
 
-  if cache[cbuf] then
-    dprint('Already attached')
+  if #paths == 0 then
     return
   end
 
-  if aucmd then
-    dprintf('Attaching (trigger=%s)', aucmd)
+  if cwd_watcher then
+    cwd_watcher:stop()
   else
-    dprint('Attaching')
-  end
-
-  if not api.nvim_buf_is_loaded(cbuf) then
-    dprint('Non-loaded buffer')
-    return
+    cwd_watcher = uv.new_fs_poll(true)
   end
 
-  local encoding = vim.bo[cbuf].fileencoding
-  if encoding == '' then
-    encoding = 'utf-8'
-  end
-  local file: string
-  local commit: string
-  local gitdir_oap: string
-  local toplevel_oap: string
-
-  if ctx then
-    gitdir_oap = ctx.gitdir
-    toplevel_oap = ctx.toplevel
-    file = ctx.toplevel .. util.path_sep .. ctx.file
-    commit = ctx.commit
-  else
-    if api.nvim_buf_line_count(cbuf) > config.max_file_length then
-      dprint('Exceeds max_file_length')
-      return
-    end
-
-    if vim.bo[cbuf].buftype ~= '' then
-      dprint('Non-normal buffer')
-      return
-    end
+  local cwd = vim.loop.cwd()
+  local gitdir, head: string, string
 
-    file, commit = get_buf_path(cbuf)
-    local file_dir = util.dirname(file)
+  local gs_cache = require('gitsigns.cache')
 
-    if not file_dir or not util.path_exists(file_dir) then
-      dprint('Not a path')
-      return
+  -- Look in the cache first
+  for _, bcache in pairs(gs_cache.cache as {number:gs_cache.CacheEntry}) do
+    local repo = bcache.git_obj.repo
+    if repo.toplevel == cwd then
+      head = repo.abbrev_head
+      gitdir = repo.gitdir
+      break
     end
-
-    gitdir_oap, toplevel_oap = on_attach_pre(cbuf)
-  end
-
-  local git_obj = git.Obj.new(file, encoding, gitdir_oap, toplevel_oap)
-
-  if not git_obj and not ctx then
-    git_obj = try_worktrees(cbuf, file, encoding)
-    scheduler()
-  end
-
-  if not git_obj then
-    dprint('Empty git obj')
-    return
-  end
-  local repo = git_obj.repo
-
-  scheduler()
-  Status:update(cbuf, {
-    head   = repo.abbrev_head,
-    root   = repo.toplevel,
-    gitdir = repo.gitdir,
-  })
-
-  if vim.startswith(file, repo.gitdir..util.path_sep) then
-    dprint('In non-standard git dir')
-    return
   end
 
-  if not ctx and (not util.path_exists(file) or uv.fs_stat(file).type == 'directory') then
-    dprint('Not a file')
-    return
-  end
-
-  if not git_obj.relpath then
-    dprint('Cannot resolve file in repo')
-    return
-  end
+  local git = require('gitsigns.git')
 
-  if not config.attach_to_untracked and git_obj.object_name == nil then
-    dprint('File is untracked')
-    return
+  if not head or not gitdir then
+    local info = git.get_repo_info(cwd)
+    gitdir = info.gitdir
+    head = info.abbrev_head
   end
 
-  -- On windows os.tmpname() crashes in callback threads so initialise this
-  -- variable on the main thread.
   scheduler()
+  vim.g.gitsigns_head = head
 
-  if config.on_attach and config.on_attach(cbuf) == false then
-    dprint('User on_attach() returned false')
+  if not gitdir then
     return
   end
 
-  cache[cbuf] = CacheEntry.new {
-    base           = ctx and ctx.base or config.base,
-    file           = file,
-    commit         = commit,
-    gitdir_watcher = manager.watch_gitdir(cbuf, repo.gitdir),
-    git_obj        = git_obj
-  }
+  local towatch = gitdir..'/HEAD'
 
-  if not api.nvim_buf_is_loaded(cbuf) then
-    dprint('Un-loaded buffer')
+  if cwd_watcher:getpath() == towatch then
+    -- Already watching
     return
   end
 
-  -- Make sure to attach before the first update (which is async) so we pick up
-  -- changes from BufReadCmd.
-  api.nvim_buf_attach(cbuf, false, {
-    on_lines  = on_lines,
-    on_reload = on_reload,
-    on_detach = on_detach
-  })
-
-  -- Initial update
-  manager.update(cbuf, cache[cbuf])
-
-  if config.keymaps and not vim.tbl_isempty(config.keymaps) then
-    require('gitsigns.mappings')(config.keymaps as {string:any}, cbuf)
-  end
-end)
+  -- Watch .git/HEAD to detect branch changes
+  cwd_watcher:start(
+    towatch,
+    config.watch_gitdir.interval,
+    void(function(err: string)
+      local __FUNC__ = 'cwd_watcher_cb'
+      if err then
+        dprintf('Git dir update error: %s', err)
+        return
+      end
+      dprint('Git cwd dir update')
 
---- Attach Gitsigns to the buffer.
----
---- Attributes: ~
----     {async}
----
---- Parameters: ~
----     {bufnr}  (number): Buffer number
----     {ctx}    (table|nil):
----              Git context data that may optionally be used to attach to any
----              buffer that represents a real git object.
----              • {file}: (string)
----                Path to the file represented by the buffer, relative to the
----                top-level.
----              • {toplevel}: (string)
----                Path to the top-level of the parent git repository.
----              • {gitdir}: (string)
----                Path to the git directory of the parent git repository
----                (typically the ".git/" directory).
----              • {commit}: (string)
----                The git revision that the file belongs to.
----              • {base}: (string|nil)
----                The git revision that the file should be compared to.
-M.attach = void(function(bufnr: integer, ctx: GitContext, _trigger: string)
-  attach_throttled(bufnr or current_buf(), ctx, _trigger)
+      local new_head = git.get_repo_info(cwd).abbrev_head
+      scheduler()
+      vim.g.gitsigns_head = new_head
+    end)
+  )
 end)
 
 local function setup_cli()
-  local funcs = M as {string:function}
   api.nvim_create_user_command('Gitsigns', function(params: api.UserCmdParams)
-    require'gitsigns.cli'.run(funcs, params)
+    require'gitsigns.cli'.run(params)
   end, {
     force = true,
     nargs = '*',
     range = true,
     complete = function(arglead: string, line: string): {string}
-      return require'gitsigns.cli'.complete(funcs, arglead, line)
+      return require'gitsigns.cli'.complete(arglead, line)
     end})
 end
 
-local function wrap_func(fn: function, ...: any): function()
-  local args = {...}
-  local nargs = select('#', ...)
-  return function()
-    fn(unpack(args, 1, nargs))
+local exported = {
+  'attach',
+  'actions'
+}
+
+local function setup_debug()
+  log.debug_mode = config.debug_mode
+  log.verbose = config._verbose
+
+  if config.debug_mode then
+    exported[#exported+1] = 'debug'
   end
 end
 
-local function autocmd(event: string, opts: function|vim.api.AutoCmdOpts)
-  local opts0: vim.api.AutoCmdOpts = {}
-  if opts is function then
-    opts0.callback = wrap_func(opts)
-  else
-    opts0 = opts
+local function setup_attach()
+  scheduler()
+
+  -- Attach to all open buffers
+  for _, buf in ipairs(api.nvim_list_bufs()) do
+    if    api.nvim_buf_is_loaded(buf)
+      and api.nvim_buf_get_name(buf) ~= '' then
+      M.attach(buf, nil, 'setup')
+      scheduler()
+    end
   end
-  opts0.group = 'gitsigns'
-  api.nvim_create_autocmd(event, opts0)
+
+  api.nvim_create_autocmd({'BufRead', 'BufNewFile', 'BufWritePost'}, {
+    group = 'gitsigns',
+    callback = function(data: vim.api.AutoCmdOpts.CallbackData)
+      M.attach(nil, nil, data.event)
+    end
+  })
 end
 
-local function on_or_after_vimenter(fn: function)
-  if vim.v.vim_did_enter == 1 then
-    fn()
-  else
-    api.nvim_create_autocmd('VimEnter', {
-      callback = wrap_func(fn),
-      once = true
-    })
-  end
+local function setup_cwd_head()
+  scheduler()
+  update_cwd_head()
+  -- Need to debounce in case some plugin changes the cwd too often
+  -- (like vim-grepper)
+  api.nvim_create_autocmd('DirChanged', {
+    group = 'gitsigns',
+    callback = function()
+      local debounce = require("gitsigns.debounce").debounce_trailing
+      debounce(100, update_cwd_head)
+    end
+  })
 end
 
 --- Setup and start Gitsigns.
@@ -417,87 +171,36 @@ M.setup = void(function(cfg: Config)
     print('gitsigns: git not in path. Aborting setup')
     return
   end
+
   if config.yadm.enable and vim.fn.executable('yadm') == 0 then
     print("gitsigns: yadm not in path. Ignoring 'yadm.enable' in config")
     config.yadm.enable = false
     return
   end
 
-  gs_debug.debug_mode = config.debug_mode
-  gs_debug.verbose = config._verbose
-
-  if config.debug_mode then
-    for nm, f in pairs(gs_debug.add_debug_functions(cache)) do
-      (M as {string:function})[nm] = f
-    end
-  end
-
-  manager.setup()
-
-  Status.formatter = config.status_formatter as function(Status.StatusObj): string
-
-  -- Make sure highlights are setup on or after VimEnter so the colorscheme is
-  -- loaded. Do not set them up with vim.schedule as this removes the intro
-  -- message.
-  on_or_after_vimenter(hl.setup_highlights)
-
+  setup_debug()
   setup_cli()
 
-  git.enable_yadm = config.yadm.enable
-  git.set_version(config._git_version)
-  scheduler()
-
-  -- Attach to all open buffers
-  for _, buf in ipairs(api.nvim_list_bufs()) do
-    if    api.nvim_buf_is_loaded(buf)
-      and api.nvim_buf_get_name(buf) ~= '' then
-      M.attach(buf, nil, 'setup')
-      scheduler()
-    end
-  end
-
   api.nvim_create_augroup('gitsigns', {})
 
-  autocmd('VimLeavePre' , M.detach_all)
-  autocmd('ColorScheme' , hl.setup_highlights)
-  autocmd('BufRead'     , wrap_func(M.attach, nil, nil, 'BufRead'))
-  autocmd('BufNewFile'  , wrap_func(M.attach, nil, nil, 'BufNewFile'))
-  autocmd('BufWritePost', wrap_func(M.attach, nil, nil, 'BufWritePost'))
-
-  autocmd('OptionSet', {
-    pattern = 'fileformat',
-    callback = function()
-      require('gitsigns.actions').refresh()
-    end}
-  )
-
-  -- vimpgrep creates and deletes lots of buffers so attaching to each one will
-  -- waste lots of resource and even slow down vimgrep.
-  autocmd('QuickFixCmdPre', {
-    pattern ='*vimgrep*',
-    callback = function()
-      vimgrep_running = true
-    end
-  })
-
-  autocmd('QuickFixCmdPost', {
-    pattern ='*vimgrep*',
-    callback = function()
-      vimgrep_running = false
-    end
-  })
+  if config._test_mode then
+    require'gitsigns.attach'._setup()
+    require'gitsigns.git'._set_version(config._git_version)
+  end
 
-  require('gitsigns.current_line_blame').setup()
+  setup_attach()
+  setup_cwd_head()
 
-  scheduler()
-  manager.update_cwd_head()
-  -- Need to debounce in case some plugin changes the cwd too often
-  -- (like vim-grepper)
-  autocmd('DirChanged', debounce_trailing(100, manager.update_cwd_head))
+  M._setup_done = true
 end)
 
 return setmetatable(M, {
   __index = function(_, f: string): any
-    return (require('gitsigns.actions') as {string:function})[f]
+    for _, mod in ipairs(exported) do
+      local m = (require as function)('gitsigns.'..mod) as table
+      if m[f] then
+        return m[f]
+      end
+    end
   end
 })
diff --git a/teal/gitsigns/attach.tl b/teal/gitsigns/attach.tl
new file mode 100644
index 00000000..86eb5eb3
--- /dev/null
+++ b/teal/gitsigns/attach.tl
@@ -0,0 +1,411 @@
+local async = require('gitsigns.async')
+local git   = require('gitsigns.git')
+
+local log        = require("gitsigns.debug.log")
+local dprintf    = log.dprintf
+local dprint     = log.dprint
+
+local manager    = require('gitsigns.manager')
+local hl         = require('gitsigns.highlight')
+
+local gs_cache   = require('gitsigns.cache')
+local cache      = gs_cache.cache
+local CacheEntry = gs_cache.CacheEntry
+local Status     = require("gitsigns.status")
+
+local gs_config  = require('gitsigns.config')
+local config     = gs_config.config
+
+local void = require('gitsigns.async').void
+local util = require('gitsigns.util')
+
+local throttle_by_id = require("gitsigns.debounce").throttle_by_id
+
+local api = vim.api
+local uv = vim.loop
+
+local record GitContext
+  toplevel: string
+  gitdir: string
+  file: string
+  commit: string
+  base: string
+end
+
+local record M
+  attach: function(cbuf: integer, ctx: GitContext, trigger: string)
+  detach: function(bufnr: integer, _keep_signs: boolean)
+  detach_all: function()
+end
+
+local vimgrep_running = false
+
+-- @return (string, string) Tuple of buffer name and commit
+local function parse_fugitive_uri(name: string): string, string
+  if vim.fn.exists('*FugitiveReal') == 0 then
+    dprint("Fugitive not installed")
+    return
+  end
+
+  local path = vim.fn.FugitiveReal(name)
+  local commit = vim.fn.FugitiveParse(name)[1]:match('([^:]+):.*')
+  if commit == '0' then
+    -- '0' means the index so clear commit so we attach normally
+    commit = nil
+  end
+  return path, commit
+end
+
+local function parse_gitsigns_uri(name: string): string, string
+  -- TODO(lewis6991): Support submodules
+  local _, _, root_path, commit, rel_path =
+    name:find([[^gitsigns://(.*)/%.git/(.*):(.*)]])
+  if commit == ':0' then
+    -- ':0' means the index so clear commit so we attach normally
+    commit = nil
+  end
+  if root_path then
+    name = root_path .. '/' .. rel_path
+  end
+  return name, commit
+end
+
+local function get_buf_path(bufnr: integer): string, string
+  local file =
+    uv.fs_realpath(api.nvim_buf_get_name(bufnr))
+      or
+    api.nvim_buf_call(bufnr, function(): string
+      return vim.fn.expand('%:p')
+    end)
+
+  if not vim.wo.diff then
+    if vim.startswith(file, 'fugitive://') then
+      local path, commit = parse_fugitive_uri(file)
+      dprintf("Fugitive buffer for file '%s' from path '%s'", path, file)
+      path = uv.fs_realpath(path)
+      if path then
+        return path, commit
+      end
+    end
+
+    if vim.startswith(file, 'gitsigns://') then
+      local path, commit = parse_gitsigns_uri(file)
+      dprintf("Gitsigns buffer for file '%s' from path '%s'", path, file)
+      path = uv.fs_realpath(path)
+      if path then
+        return path, commit
+      end
+    end
+  end
+
+  return file
+end
+
+local function on_lines(_, bufnr: integer, _, first: integer, last_orig: integer, last_new: integer, byte_count: integer): boolean
+  if first == last_orig and last_orig == last_new and byte_count == 0 then
+    -- on_lines can be called twice for undo events; ignore the second
+    -- call which indicates no changes.
+    return
+  end
+  return manager.on_lines(bufnr, first, last_orig, last_new)
+end
+
+local function on_reload(_, bufnr: integer)
+  local __FUNC__ = 'on_reload'
+  dprint('Reload')
+  manager.update_debounced(bufnr)
+end
+
+local function on_detach(_, bufnr: integer)
+  M.detach(bufnr, true)
+end
+
+local function on_attach_pre(bufnr: integer): string, string
+  local gitdir, toplevel: string, string
+  if config._on_attach_pre then
+    local res: any = async.wrap(config._on_attach_pre, 2)(bufnr)
+    dprintf('ran on_attach_pre with result %s', vim.inspect(res))
+    if res is table then
+      if type(res.gitdir) == 'string' then
+        gitdir = res.gitdir as string
+      end
+      if type(res.toplevel) == 'string' then
+        toplevel = res.toplevel as string
+      end
+    end
+  end
+  return gitdir, toplevel
+end
+
+local function try_worktrees(_bufnr: integer, file: string, encoding: string): git.Obj
+  if not config.worktrees then
+    return
+  end
+
+  for _, wt in ipairs(config.worktrees) do
+    local git_obj = git.Obj.new(file, encoding, wt.gitdir, wt.toplevel)
+    if git_obj and git_obj.object_name then
+      dprintf('Using worktree %s', vim.inspect(wt))
+      return git_obj
+    end
+  end
+end
+
+local done_setup = false
+
+function M._setup()
+  if done_setup then
+    return
+  end
+
+  done_setup = true
+
+  manager.setup()
+
+  hl.setup_highlights()
+  api.nvim_create_autocmd('ColorScheme', {
+    group = 'gitsigns',
+    callback = hl.setup_highlights
+  })
+
+  api.nvim_create_autocmd('OptionSet', {
+    group = 'gitsigns',
+    pattern = 'fileformat',
+    callback = function()
+      require('gitsigns.actions').refresh()
+    end}
+  )
+
+  -- vimpgrep creates and deletes lots of buffers so attaching to each one will
+  -- waste lots of resource and even slow down vimgrep.
+  api.nvim_create_autocmd('QuickFixCmdPre', {
+    group = 'gitsigns',
+    pattern ='*vimgrep*',
+    callback = function()
+      vimgrep_running = true
+    end
+  })
+
+  api.nvim_create_autocmd('QuickFixCmdPost', {
+    group = 'gitsigns',
+    pattern ='*vimgrep*',
+    callback = function()
+      vimgrep_running = false
+    end
+  })
+
+  require('gitsigns.current_line_blame').setup()
+
+  api.nvim_create_autocmd('VimLeavePre' , {
+    group = 'gitsigns',
+    callback = M.detach_all
+  })
+
+end
+
+-- Ensure attaches cannot be interleaved.
+-- Since attaches are asynchronous we need to make sure an attach isn't
+-- performed whilst another one is in progress.
+local attach_throttled = throttle_by_id(function(cbuf: integer, ctx: GitContext, aucmd: string)
+  local __FUNC__ = 'attach'
+
+  M._setup()
+
+  if vimgrep_running then
+    dprint('attaching is disabled')
+    return
+  end
+
+  if cache[cbuf] then
+    dprint('Already attached')
+    return
+  end
+
+  if aucmd then
+    dprintf('Attaching (trigger=%s)', aucmd)
+  else
+    dprint('Attaching')
+  end
+
+  if not api.nvim_buf_is_loaded(cbuf) then
+    dprint('Non-loaded buffer')
+    return
+  end
+
+  local encoding = vim.bo[cbuf].fileencoding
+  if encoding == '' then
+    encoding = 'utf-8'
+  end
+  local file: string
+  local commit: string
+  local gitdir_oap: string
+  local toplevel_oap: string
+
+  if ctx then
+    gitdir_oap = ctx.gitdir
+    toplevel_oap = ctx.toplevel
+    file = ctx.toplevel .. util.path_sep .. ctx.file
+    commit = ctx.commit
+  else
+    if api.nvim_buf_line_count(cbuf) > config.max_file_length then
+      dprint('Exceeds max_file_length')
+      return
+    end
+
+    if vim.bo[cbuf].buftype ~= '' then
+      dprint('Non-normal buffer')
+      return
+    end
+
+    file, commit = get_buf_path(cbuf)
+    local file_dir = util.dirname(file)
+
+    if not file_dir or not util.path_exists(file_dir) then
+      dprint('Not a path')
+      return
+    end
+
+    gitdir_oap, toplevel_oap = on_attach_pre(cbuf)
+  end
+
+  local git_obj = git.Obj.new(file, encoding, gitdir_oap, toplevel_oap)
+
+  if not git_obj and not ctx then
+    git_obj = try_worktrees(cbuf, file, encoding)
+    async.scheduler()
+  end
+
+  if not git_obj then
+    dprint('Empty git obj')
+    return
+  end
+  local repo = git_obj.repo
+
+  async.scheduler()
+  Status:update(cbuf, {
+    head   = repo.abbrev_head,
+    root   = repo.toplevel,
+    gitdir = repo.gitdir,
+  })
+
+  if vim.startswith(file, repo.gitdir..util.path_sep) then
+    dprint('In non-standard git dir')
+    return
+  end
+
+  if not ctx and (not util.path_exists(file) or uv.fs_stat(file).type == 'directory') then
+    dprint('Not a file')
+    return
+  end
+
+  if not git_obj.relpath then
+    dprint('Cannot resolve file in repo')
+    return
+  end
+
+  if not config.attach_to_untracked and git_obj.object_name == nil then
+    dprint('File is untracked')
+    return
+  end
+
+  -- On windows os.tmpname() crashes in callback threads so initialise this
+  -- variable on the main thread.
+  async.scheduler()
+
+  if config.on_attach and config.on_attach(cbuf) == false then
+    dprint('User on_attach() returned false')
+    return
+  end
+
+  cache[cbuf] = CacheEntry.new {
+    base           = ctx and ctx.base or config.base,
+    file           = file,
+    commit         = commit,
+    gitdir_watcher = manager.watch_gitdir(cbuf, repo.gitdir),
+    git_obj        = git_obj
+  }
+
+  if not api.nvim_buf_is_loaded(cbuf) then
+    dprint('Un-loaded buffer')
+    return
+  end
+
+  -- Make sure to attach before the first update (which is async) so we pick up
+  -- changes from BufReadCmd.
+  api.nvim_buf_attach(cbuf, false, {
+    on_lines  = on_lines,
+    on_reload = on_reload,
+    on_detach = on_detach
+  })
+
+  -- Initial update
+  manager.update(cbuf, cache[cbuf])
+
+  if config.keymaps and not vim.tbl_isempty(config.keymaps) then
+    require('gitsigns.mappings')(config.keymaps as {string:any}, cbuf)
+  end
+end)
+
+--- Detach Gitsigns from all buffers it is attached to.
+function M.detach_all()
+  for k, _ in pairs(cache as {integer:CacheEntry}) do
+    M.detach(k)
+  end
+end
+
+--- Detach Gitsigns from the buffer {bufnr}. If {bufnr} is not
+--- provided then the current buffer is used.
+---
+--- Parameters: ~
+---     {bufnr}  (number): Buffer number
+function M.detach(bufnr: integer, _keep_signs: boolean)
+  -- When this is called interactively (with no arguments) we want to remove all
+  -- the signs, however if called via a detach event (due to nvim_buf_attach)
+  -- then we don't want to clear the signs in case the buffer is just being
+  -- updated due to the file externally changing. When this happens a detach and
+  -- attach event happen in sequence and so we keep the old signs to stop the
+  -- sign column width moving about between updates.
+  bufnr = bufnr or api.nvim_get_current_buf()
+  dprint('Detached')
+  local bcache = cache[bufnr]
+  if not bcache then
+    dprint('Cache was nil')
+    return
+  end
+
+  manager.detach(bufnr, _keep_signs)
+
+  -- Clear status variables
+  Status:clear(bufnr)
+
+  cache:destroy(bufnr)
+end
+
+
+--- Attach Gitsigns to the buffer.
+---
+--- Attributes: ~
+---     {async}
+---
+--- Parameters: ~
+---     {bufnr}  (number): Buffer number
+---     {ctx}    (table|nil):
+---              Git context data that may optionally be used to attach to any
+---              buffer that represents a real git object.
+---              • {file}: (string)
+---                Path to the file represented by the buffer, relative to the
+---                top-level.
+---              • {toplevel}: (string)
+---                Path to the top-level of the parent git repository.
+---              • {gitdir}: (string)
+---                Path to the git directory of the parent git repository
+---                (typically the ".git/" directory).
+---              • {commit}: (string)
+---                The git revision that the file belongs to.
+---              • {base}: (string|nil)
+---                The git revision that the file should be compared to.
+M.attach = void(function(bufnr: integer, ctx: GitContext, _trigger: string)
+  attach_throttled(bufnr or api.nvim_get_current_buf(), ctx, _trigger)
+end)
+
+return M
diff --git a/teal/gitsigns/cli.tl b/teal/gitsigns/cli.tl
index 1c890b94..95cf23d9 100644
--- a/teal/gitsigns/cli.tl
+++ b/teal/gitsigns/cli.tl
@@ -1,12 +1,22 @@
 local async = require('gitsigns.async')
 local void = require('gitsigns.async').void
 
-local gs_debug   = require("gitsigns.debug")
-local dprintf    = gs_debug.dprintf
-local message    = require'gitsigns.message'
+local log     = require('gitsigns.debug.log')
+local dprintf = log.dprintf
+local message = require'gitsigns.message'
 
 local parse_args = require('gitsigns.cli.argparse').parse_args
 
+local actions = require('gitsigns.actions')
+local attach = require('gitsigns.attach')
+local gs_debug = require('gitsigns.debug')
+
+local sources = {
+  [actions] = true,
+  [attach] = false,
+  [gs_debug] = false
+} as {{string:function}:boolean}
+
 -- try to parse each argument as a lua boolean, nil or number, if fails then
 -- keep argument as a string:
 --
@@ -26,18 +36,17 @@ local function parse_to_lua(a: string): any
 end
 
 local record M
-  run : function(funcs: {string:function}, params: vim.api.UserCmdParams)
+  run: function(params: vim.api.UserCmdParams)
 end
 
-function M.complete(funcs: {string:function}, arglead: string, line: string): {string}
+function M.complete(arglead: string, line: string): {string}
   local words = vim.split(line, '%s+')
   local n: integer = #words
 
-  local actions = require('gitsigns.actions')
   local matches: {string} = {}
   if n == 2 then
-    for _, m in ipairs{actions as {string:function}, funcs} do
-      for func, _ in pairs(m) do
+    for m, _ in pairs(sources) do
+      for func, _ in pairs(m as {string:function}) do
         if not func:match('^[a-z]') then
           -- exclude
         elseif vim.startswith(func, arglead) then
@@ -55,22 +64,20 @@ function M.complete(funcs: {string:function}, arglead: string, line: string): {s
   return matches
 end
 
-M.run = void(function(funcs: {string:function}, params: vim.api.UserCmdParams)
+M.run = void(function(params: vim.api.UserCmdParams)
+  local __FUNC__ = 'cli.run'
   local pos_args_raw, named_args_raw = parse_args(params.args)
 
   local func = pos_args_raw[1]
 
   if not func then
-    func = async.wrap(vim.ui.select, 3)(M.complete(funcs, '', 'Gitsigns '), {})
+    func = async.wrap(vim.ui.select, 3)(M.complete('', 'Gitsigns '), {})
   end
 
   local pos_args = vim.tbl_map(parse_to_lua, vim.list_slice(pos_args_raw, 2)) as {any}
   local named_args = vim.tbl_map(parse_to_lua, named_args_raw) as {string:any}
   local args = vim.tbl_extend('error', pos_args, named_args)
 
-  local actions = require('gitsigns.actions')
-  local actions0 = actions as {string:function}
-
   dprintf("Running action '%s' with arguments %s", func, vim.inspect(args, {newline=' ', indent=''}))
 
   local cmd_func = actions._get_cmd_func(func)
@@ -81,15 +88,13 @@ M.run = void(function(funcs: {string:function}, params: vim.api.UserCmdParams)
     return
   end
 
-  if type(actions0[func]) == 'function' then
-    actions0[func](unpack(pos_args), named_args)
-    return
-  end
-
-  if type(funcs[func]) == 'function' then
-    -- Note functions here do not have named arguments
-    funcs[func](unpack(pos_args))
-    return
+  for m, has_named in pairs(sources) do
+    local f = (m as {string:any})[func]
+    if f is function then
+      -- Note functions here do not have named arguments
+      f(unpack(pos_args), has_named and named_args or nil)
+      return
+    end
   end
 
   message.error('%s is not a valid function or action', func)
diff --git a/teal/gitsigns/config.tl b/teal/gitsigns/config.tl
index 29b61549..94db3bb7 100644
--- a/teal/gitsigns/config.tl
+++ b/teal/gitsigns/config.tl
@@ -129,6 +129,7 @@ local record M
 
     _git_version: string
     _verbose: boolean
+    _test_mode: boolean
   end
 
   schema: {string:SchemaElem}
@@ -712,6 +713,11 @@ M.schema = {
     ]]
   },
 
+  _test_mode = {
+    type = 'boolean',
+    default = false,
+  },
+
   word_diff = {
     type = 'boolean',
     default = false,
diff --git a/teal/gitsigns/debug.tl b/teal/gitsigns/debug.tl
index a50597ef..edaa4f8a 100644
--- a/teal/gitsigns/debug.tl
+++ b/teal/gitsigns/debug.tl
@@ -1,110 +1,6 @@
-local M = {
-  debug_mode = false,
-  verbose = false,
-  messages: {string} = {}
-}
+local log = require'gitsigns.debug.log'
 
-local function getvarvalue(name: string, lvl: integer): any
-  lvl = lvl + 1
-  local value: any
-  local found: boolean
-
-  -- try local variables
-  local i = 1
-  while true do
-    local n, v = debug.getlocal(lvl as function, i) as (string, any)
-    if not n then break end
-    if n == name then
-      value = v
-      found = true
-    end
-    i = i + 1
-  end
-  if found then return value end
-
-  -- try upvalues
-  local func = debug.getinfo(lvl).func as function
-  i = 1
-  while true do
-    local n, v = debug.getupvalue(func, i) as (string, any)
-    if not n then break end
-    if n == name then return v end
-    i = i + 1
-  end
-
-  -- not found; get global
-  return getfenv(func)[name]
-end
-
-local function get_context(lvl: integer): table
-  lvl = lvl + 1
-  local ret: table = {}
-  ret.name = getvarvalue('__FUNC__', lvl) as string
-  if not ret.name then
-    local name0 = debug.getinfo(lvl, 'n').name or ''
-    ret.name = name0:gsub('(.*)%d+$', '%1')
-  end
-  ret.bufnr = getvarvalue('bufnr', lvl)
-    or getvarvalue('_bufnr', lvl)
-    or getvarvalue('cbuf', lvl)
-    or getvarvalue('buf', lvl)
-
-  return ret
-end
-
--- If called in a callback then make sure the callback defines a __FUNC__
--- variable which can be used to identify the name of the function.
-local function cprint(obj: any, lvl: integer)
-  lvl = lvl + 1
-  local msg = obj is string and obj or vim.inspect(obj)
-  local ctx = get_context(lvl)
-  local msg2: string
-  if ctx.bufnr then
-    msg2 = string.format('%s(%s): %s', ctx.name, ctx.bufnr, msg)
-  else
-    msg2 = string.format('%s: %s', ctx.name, msg)
-  end
-  table.insert(M.messages, msg2)
-end
-
-function M.dprint(obj: any)
-  if not M.debug_mode then return end
-  cprint(obj, 2)
-end
-
-function M.dprintf(obj: string, ...:any)
-  if not M.debug_mode then return end
-  cprint(obj:format(...), 2)
-end
-
-function M.vprint(obj: any)
-  if not (M.debug_mode and M.verbose) then return end
-  cprint(obj, 2)
-end
-
-function M.vprintf(obj: string, ...:any)
-  if not (M.debug_mode and M.verbose) then return end
-  cprint(obj:format(...), 2)
-end
-
-local function eprint(msg: string, level: integer)
-  local info = debug.getinfo(level+2, 'Sl')
-  if info then
-    msg = string.format('(ERROR) %s(%d): %s', info.short_src, info.currentline, msg)
-  end
-  M.messages[#M.messages+1] = msg
-  if M.debug_mode then
-    error(msg)
-  end
-end
-
-function M.eprint(msg: string)
-  eprint(msg, 1)
-end
-
-function M.eprintf(fmt: string, ...:any)
-  eprint(fmt:format(...), 1)
-end
+local M = {}
 
 local function process(raw_item: any, path: {string}): any
   if path[#path] == vim.inspect.METATABLE then
@@ -123,28 +19,25 @@ local function process(raw_item: any, path: {string}): any
   return raw_item
 end
 
-function M.add_debug_functions(cache: any): {string:function}
-  local R: {string:function} = {}
-  R.dump_cache = function(): any
-    local text = vim.inspect(cache, { process = process })
-    vim.api.nvim_echo({{text}}, false, {})
-    return cache
-  end
+function M.dump_cache(): any
+  -- TODO(lewis6991): hack: use package.loaded to avoid circular deps
+  local cache = (package.loaded['gitsigns.cache'] as table).cache
+  local text = vim.inspect(cache, { process = process })
+  vim.api.nvim_echo({{text}}, false, {})
+  return cache
+end
 
-  R.debug_messages = function(noecho: boolean): {string}
-    if not noecho then
-      for _, m in ipairs(M.messages) do
-        vim.api.nvim_echo({{m}}, false, {})
-      end
+function M.debug_messages(noecho: boolean): {string}
+  if not noecho then
+    for _, m in ipairs(log.messages) do
+      vim.api.nvim_echo({{m}}, false, {})
     end
-    return M.messages
-  end
-
-  R.clear_debug = function()
-    M.messages = {}
   end
+  return log.messages
+end
 
-  return R
+function M.clear_debug()
+  log.messages = {}
 end
 
 return M
diff --git a/teal/gitsigns/debug/log.tl b/teal/gitsigns/debug/log.tl
new file mode 100644
index 00000000..3557f22b
--- /dev/null
+++ b/teal/gitsigns/debug/log.tl
@@ -0,0 +1,109 @@
+local M = {
+  debug_mode = false,
+  verbose = false,
+  messages: {string} = {},
+}
+
+local function getvarvalue(name: string, lvl: integer): any
+  lvl = lvl + 1
+  local value: any
+  local found: boolean
+
+  -- try local variables
+  local i = 1
+  while true do
+    local n, v = debug.getlocal(lvl as function, i) as (string, any)
+    if not n then break end
+    if n == name then
+      value = v
+      found = true
+    end
+    i = i + 1
+  end
+  if found then return value end
+
+  -- try upvalues
+  local func = debug.getinfo(lvl).func as function
+  i = 1
+  while true do
+    local n, v = debug.getupvalue(func, i) as (string, any)
+    if not n then break end
+    if n == name then return v end
+    i = i + 1
+  end
+
+  -- not found; get global
+  return getfenv(func)[name]
+end
+
+local function get_context(lvl: integer): table
+  lvl = lvl + 1
+  local ret: table = {}
+  ret.name = getvarvalue('__FUNC__', lvl) as string
+  if not ret.name then
+    local name0 = debug.getinfo(lvl, 'n').name or ''
+    ret.name = name0:gsub('(.*)%d+$', '%1')
+  end
+  ret.bufnr = getvarvalue('bufnr', lvl)
+    or getvarvalue('_bufnr', lvl)
+    or getvarvalue('cbuf', lvl)
+    or getvarvalue('buf', lvl)
+
+  return ret
+end
+
+-- If called in a callback then make sure the callback defines a __FUNC__
+-- variable which can be used to identify the name of the function.
+local function cprint(obj: any, lvl: integer)
+  lvl = lvl + 1
+  local msg = obj is string and obj or vim.inspect(obj)
+  local ctx = get_context(lvl)
+  local msg2: string
+  if ctx.bufnr then
+    msg2 = string.format('%s(%s): %s', ctx.name, ctx.bufnr, msg)
+  else
+    msg2 = string.format('%s: %s', ctx.name, msg)
+  end
+  table.insert(M.messages, msg2)
+end
+
+function M.dprint(obj: any)
+  if not M.debug_mode then return end
+  cprint(obj, 2)
+end
+
+function M.dprintf(obj: string, ...:any)
+  if not M.debug_mode then return end
+  cprint(obj:format(...), 2)
+end
+
+function M.vprint(obj: any)
+  if not (M.debug_mode and M.verbose) then return end
+  cprint(obj, 2)
+end
+
+function M.vprintf(obj: string, ...:any)
+  if not (M.debug_mode and M.verbose) then return end
+  cprint(obj:format(...), 2)
+end
+
+local function eprint(msg: string, level: integer)
+  local info = debug.getinfo(level+2, 'Sl')
+  if info then
+    msg = string.format('(ERROR) %s(%d): %s', info.short_src, info.currentline, msg)
+  end
+  M.messages[#M.messages+1] = msg
+  if M.debug_mode then
+    error(msg)
+  end
+end
+
+function M.eprint(msg: string)
+  eprint(msg, 1)
+end
+
+function M.eprintf(fmt: string, ...:any)
+  eprint(fmt:format(...), 1)
+end
+
+return M
diff --git a/teal/gitsigns/git.tl b/teal/gitsigns/git.tl
index 59c7b1d3..9f34d6e5 100644
--- a/teal/gitsigns/git.tl
+++ b/teal/gitsigns/git.tl
@@ -1,18 +1,21 @@
 local async = require('gitsigns.async')
 local scheduler = require('gitsigns.async').scheduler
 
-local gsd = require("gitsigns.debug")
+local log = require("gitsigns.debug.log")
 local util = require('gitsigns.util')
 local subprocess = require('gitsigns.subprocess')
 
+local gs_config  = require('gitsigns.config')
+local config     = gs_config.config
+
 local gs_hunks = require("gitsigns.hunks")
 local Hunk = gs_hunks.Hunk
 
 local uv = vim.loop
 local startswith = vim.startswith
 
-local dprint = require("gitsigns.debug").dprint
-local eprint = require("gitsigns.debug").eprint
+local dprint = require('gitsigns.debug.log').dprint
+local eprint = require('gitsigns.debug.log').eprint
 local err = require('gitsigns.message').error
 
 local record GJobSpec
@@ -56,10 +59,6 @@ local record M
   end
   version: Version
 
-  enable_yadm: boolean
-
-  set_version: function(string)
-
   record RepoInfo
     gitdir: string
     toplevel: string
@@ -167,8 +166,35 @@ local function check_version(version: {number,number,number}): boolean
   return true
 end
 
+--- @async
+function M._set_version(version: string)
+  if version ~= 'auto' then
+    M.version = parse_version(version)
+    return
+  end
+
+  local _, _, stdout, stderr = async.wait(2, subprocess.run_job, {
+    command = 'git', args = { '--version' }
+  })
+
+  local line = vim.split(stdout or '', '\n', true)[1]
+  if not line then
+    err("Unable to detect git version as 'git --version' failed to return anything")
+    eprint(stderr)
+    return
+  end
+  assert(type(line) == 'string', 'Unexpected output: '..line)
+  assert(startswith(line, 'git version'), 'Unexpected output: '..line)
+  local parts = vim.split(line, '%s+')
+  M.version = parse_version(parts[3])
+end
+
+
 --- @async
 local git_command = async.create(function(args: {string}, spec: GJobSpec): {string}, string
+  if not M.version then
+    M._set_version(config._git_version)
+  end
   spec = spec or {}
   spec.command = spec.command or 'git'
   spec.args = spec.command == 'git' and {
@@ -187,7 +213,7 @@ local git_command = async.create(function(args: {string}, spec: GJobSpec): {stri
   if not spec.suppress_stderr then
     if stderr then
       local cmd_str = table.concat({spec.command, unpack(args)}, ' ')
-      gsd.eprintf("Recieved stderr when running command\n'%s':\n%s", cmd_str, stderr)
+      log.eprintf("Recieved stderr when running command\n'%s':\n%s", cmd_str, stderr)
     end
   end
 
@@ -199,10 +225,10 @@ local git_command = async.create(function(args: {string}, spec: GJobSpec): {stri
     stdout_lines[#stdout_lines] = nil
   end
 
-  if gsd.verbose then
-    gsd.vprintf('%d lines:', #stdout_lines)
+  if log.verbose then
+    log.vprintf('%d lines:', #stdout_lines)
     for i = 1, math.min(10, #stdout_lines) do
-      gsd.vprintf('\t%s', stdout_lines[i])
+      log.vprintf('\t%s', stdout_lines[i])
     end
   end
 
@@ -235,7 +261,7 @@ local function process_abbrev_head(gitdir: string, head_str: string, path: strin
         suppress_stderr = true,
         cwd = path,
       })[1] or ''
-    if gsd.debug_mode and short_sha ~= '' then
+    if log.debug_mode and short_sha ~= '' then
       short_sha = 'HEAD'
     end
     if util.path_exists(gitdir..'/rebase-merge')
@@ -310,25 +336,6 @@ function M.get_repo_info(path: string, cmd: string, gitdir: string, toplevel: st
   return ret
 end
 
---- @async
-function M.set_version(version: string)
-  if version ~= 'auto' then
-    M.version = parse_version(version)
-    return
-  end
-  local results, stderr = git_command{'--version'}
-  local line = results[1]
-  if not line then
-    err("Unable to detect git version as 'git --version' failed to return anything")
-    eprint(stderr)
-    return
-  end
-  assert(type(line) == 'string', 'Unexpected output: '..line)
-  assert(startswith(line, 'git version'), 'Unexpected output: '..line)
-  local parts = vim.split(line, '%s+')
-  M.version = parse_version(parts[3])
-end
-
 --------------------------------------------------------------------------------
 -- Git repo object methods
 --------------------------------------------------------------------------------
@@ -444,7 +451,7 @@ function Repo.new(dir: string, gitdir: string, toplevel: string): Repo
   end
 
   -- Try yadm
-  if M.enable_yadm and not self.gitdir then
+  if config.yadm.enable and not self.gitdir then
     if vim.startswith(dir, os.getenv('HOME'))
       and #git_command({'ls-files', dir}, {command = 'yadm'}) ~= 0 then
       M.get_repo_info(dir, 'yadm', gitdir, toplevel)
@@ -501,7 +508,7 @@ function Obj:file_info(file: string, silent: boolean): M.FileProps
     -- Suppress_stderr for the cases when we run:
     --   git ls-files --others exists/nonexist
     if not stderr:match('^warning: could not open directory .*: No such file or directory') then
-      gsd.eprint(stderr)
+      log.eprint(stderr)
     end
   end
 
diff --git a/teal/gitsigns/highlight.tl b/teal/gitsigns/highlight.tl
index 6d25a7eb..9d68b96f 100644
--- a/teal/gitsigns/highlight.tl
+++ b/teal/gitsigns/highlight.tl
@@ -168,8 +168,11 @@ local function cmul(x: integer, factor: number): integer
   return math.floor(math.floor(r*factor) * 2^16 + math.floor(g*factor) * 2^8 + math.floor(b*factor))
 end
 
+local function dprintf(fmt: string, ...:any)
+  require('gitsigns.debug.log').dprintf(fmt, ...)
+end
+
 local function derive(hl: string, hldef: Hldef)
-  local dprintf = require("gitsigns.debug").dprintf
   for _, d in ipairs(hldef) do
     if is_hl_set(d) then
       dprintf('Deriving %s from %s', hl, d)
@@ -201,7 +204,6 @@ end
 -- Setup a GitSign* highlight by deriving it from other potentially present
 -- highlights.
 M.setup_highlights = function()
-  local dprintf = require("gitsigns.debug").dprintf
   for _, hlg in ipairs(M.hls) do
     for hl, hldef in pairs(hlg) do
       if is_hl_set(hl) then
diff --git a/teal/gitsigns/manager.tl b/teal/gitsigns/manager.tl
index 52051e08..bba5363a 100644
--- a/teal/gitsigns/manager.tl
+++ b/teal/gitsigns/manager.tl
@@ -12,15 +12,14 @@ local Status            = require("gitsigns.status")
 local debounce_trailing = require('gitsigns.debounce').debounce_trailing
 local throttle_by_id    = require('gitsigns.debounce').throttle_by_id
 
-local gs_debug          = require("gitsigns.debug")
-local dprint            = gs_debug.dprint
-local dprintf           = gs_debug.dprintf
-local eprint            = gs_debug.eprint
+local log               = require('gitsigns.debug.log')
+local dprint            = log.dprint
+local dprintf           = log.dprintf
+local eprint            = log.eprint
 
 local subprocess        = require('gitsigns.subprocess')
 local util              = require('gitsigns.util')
 local run_diff          = require('gitsigns.diff')
-local git               = require('gitsigns.git')
 local uv                = require('gitsigns.uv')
 
 local gs_hunks          = require("gitsigns.hunks")
@@ -38,7 +37,6 @@ local record M
   update_debounced : function(bufnr: integer, CacheEntry)
   on_lines         : function(buf: integer, first: integer, last_orig: integer, last_new: integer): boolean
   watch_gitdir     : function(bufnr: integer, gitdir: string): vim.loop.FSPollObj
-  update_cwd_head  : function()
   detach           : function(bufnr: integer, keep_signs: boolean)
   reset_signs      : function()
   setup            : function()
@@ -444,67 +442,6 @@ function M.watch_gitdir(bufnr: integer, gitdir: string): vim.loop.FSPollObj
   return w
 end
 
-local cwd_watcher: vim.loop.FSPollObj
-
-M.update_cwd_head = void(function()
-  if cwd_watcher then
-    cwd_watcher:stop()
-  else
-    cwd_watcher = uv.new_fs_poll(true)
-  end
-
-  local cwd = vim.loop.cwd()
-  local gitdir, head: string, string
-
-  -- Look in the cache first
-  for _, bcache in pairs(cache as {number:CacheEntry}) do
-    local repo = bcache.git_obj.repo
-    if repo.toplevel == cwd then
-      head = repo.abbrev_head
-      gitdir = repo.gitdir
-      break
-    end
-  end
-
-  if not head or not gitdir then
-    local info = git.get_repo_info(cwd)
-    gitdir = info.gitdir
-    head = info.abbrev_head
-  end
-
-  scheduler()
-  vim.g.gitsigns_head = head
-
-  if not gitdir then
-    return
-  end
-
-  local towatch = gitdir..'/HEAD'
-
-  if cwd_watcher:getpath() == towatch then
-    -- Already watching
-    return
-  end
-
-  -- Watch .git/HEAD to detect branch changes
-  cwd_watcher:start(
-    towatch,
-    config.watch_gitdir.interval,
-    void(function(err: string)
-      local __FUNC__ = 'cwd_watcher_cb'
-      if err then
-        dprintf('Git dir update error: %s', err)
-        return
-      end
-      dprint('Git cwd dir update')
-
-      local new_head = git.get_repo_info(cwd).abbrev_head
-      scheduler()
-      vim.g.gitsigns_head = new_head
-    end)
-  )
-end)
-
 function M.reset_signs()
   -- Remove all signs
   signs_normal:reset()
diff --git a/teal/gitsigns/signs.tl b/teal/gitsigns/signs.tl
index 0eed091f..953b164f 100644
--- a/teal/gitsigns/signs.tl
+++ b/teal/gitsigns/signs.tl
@@ -1,7 +1,7 @@
 local config = require('gitsigns.config').config
 local SignsConfig = require('gitsigns.config').Config.SignsConfig
 
-local dprint = require('gitsigns.debug').dprint
+local dprint = require('gitsigns.debug.log').dprint
 
 local B = require('gitsigns.signs.base')
 
diff --git a/teal/gitsigns/status.tl b/teal/gitsigns/status.tl
index d9ba9f06..b6992d97 100644
--- a/teal/gitsigns/status.tl
+++ b/teal/gitsigns/status.tl
@@ -1,5 +1,6 @@
 local api = vim.api
 
+
 local record StatusObj
   added   : integer
   removed : integer
@@ -11,7 +12,6 @@ end
 
 local Status = {
   StatusObj = StatusObj,
-  formatter: function(StatusObj): string = nil
 }
 
 function Status:update(bufnr: integer, status: StatusObj)
@@ -24,7 +24,10 @@ function Status:update(bufnr: integer, status: StatusObj)
   end
   vim.b[bufnr].gitsigns_head = status.head or ''
   vim.b[bufnr].gitsigns_status_dict = status
-  vim.b[bufnr].gitsigns_status = self.formatter(status)
+
+  local config = require('gitsigns.config').config
+
+  vim.b[bufnr].gitsigns_status = config.status_formatter(status)
 end
 
 function Status:clear(bufnr: integer)
diff --git a/teal/gitsigns/subprocess.tl b/teal/gitsigns/subprocess.tl
index a6da1cab..3250ecf7 100644
--- a/teal/gitsigns/subprocess.tl
+++ b/teal/gitsigns/subprocess.tl
@@ -1,4 +1,4 @@
-local gsd = require("gitsigns.debug")
+local log = require("gitsigns.debug.log")
 local guv = require("gitsigns.uv")
 local uv = vim.loop
 
@@ -47,7 +47,7 @@ end
 local function handle_reader(pipe: uv.Pipe, output: {string})
   pipe:read_start(function(err: string, data: string)
     if err then
-      gsd.eprint(err)
+      log.eprint(err)
     end
     if data then
       output[#output+1] = data
@@ -59,9 +59,9 @@ end
 
 function M.run_job(obj: M.JobSpec, callback: function(integer, integer, string, string))
   local __FUNC__ = 'run_job'
-  if gsd.debug_mode then
+  if log.debug_mode then
     local cmd: string = obj.command..' '..table.concat(obj.args, ' ')
-    gsd.dprint(cmd)
+    log.dprint(cmd)
   end
 
   local stdout_data: {string} = {}
@@ -75,7 +75,7 @@ function M.run_job(obj: M.JobSpec, callback: function(integer, integer, string,
   end
 
   local handle, pid: uv.Process, integer
-  handle, pid = guv.spawn(obj.command, {
+  handle, pid = vim.loop.spawn(obj.command, {
     args  = obj.args,
     stdio = { stdin, stdout, stderr },
     cwd   = obj.cwd
diff --git a/test/gitdir_watcher_spec.lua b/test/gitdir_watcher_spec.lua
index 7bf9ffb5..845e3345 100644
--- a/test/gitdir_watcher_spec.lua
+++ b/test/gitdir_watcher_spec.lua
@@ -41,30 +41,26 @@ describe('gitdir_watcher', function()
   end)
 
   it('can follow moved files', function()
-    local screen = Screen.new(20, 17)
-    screen:attach({ext_messages=false})
     setup_test_repo()
     setup_gitsigns(test_config)
     command('Gitsigns clear_debug')
     edit(test_file)
 
-    local test_file2 = test_file..'2'
-    local test_file3 = test_file..'3'
-
     match_debug_messages {
-      'attach(1): Attaching (trigger=BufRead)',
+      'attach(1): Attaching (trigger=BufReadPost)',
       p"run_job: git .* config user.name",
       p"run_job: git .* rev%-parse %-%-show%-toplevel %-%-absolute%-git%-dir %-%-abbrev%-ref HEAD",
       p('run_job: git .* ls%-files .* '..helpers.pesc(test_file)),
       'watch_gitdir(1): Watching git dir',
       p'run_job: git .* show :0:dummy.txt',
-      'update(1): updates: 1, jobs: 6',
+      'update(1): updates: 1, jobs: 5',
     }
 
     eq({[1] = test_file}, get_bufs())
 
     command('Gitsigns clear_debug')
 
+    local test_file2 = test_file..'2'
     git{'mv', test_file, test_file2}
 
     match_debug_messages {
@@ -76,13 +72,14 @@ describe('gitdir_watcher', function()
       p('run_job: git .* ls%-files .* '..helpers.pesc(test_file2)),
       p'handle_moved%(1%): Renamed buffer 1 from .*/dummy.txt to .*/dummy.txt2',
       p'run_job: git .* show :0:dummy.txt2',
-      'update(1): updates: 2, jobs: 11'
+      'update(1): updates: 2, jobs: 10'
     }
 
     eq({[1] = test_file2}, get_bufs())
 
     command('Gitsigns clear_debug')
 
+    local test_file3 = test_file..'3'
     git{'mv', test_file2, test_file3}
 
     match_debug_messages {
@@ -94,7 +91,7 @@ describe('gitdir_watcher', function()
       p('run_job: git .* ls%-files .* '..helpers.pesc(test_file3)),
       p'handle_moved%(1%): Renamed buffer 1 from .*/dummy.txt2 to .*/dummy.txt3',
       p'run_job: git .* show :0:dummy.txt3',
-      'update(1): updates: 3, jobs: 16'
+      'update(1): updates: 3, jobs: 15'
     }
 
     eq({[1] = test_file3}, get_bufs())
@@ -113,7 +110,7 @@ describe('gitdir_watcher', function()
       p('run_job: git .* ls%-files .* '..helpers.pesc(test_file)),
       p'handle_moved%(1%): Renamed buffer 1 from .*/dummy.txt3 to .*/dummy.txt',
       p'run_job: git .* show :0:dummy.txt',
-      'update(1): updates: 4, jobs: 22'
+      'update(1): updates: 4, jobs: 21'
     }
 
     eq({[1] = test_file}, get_bufs())
diff --git a/test/gitsigns_spec.lua b/test/gitsigns_spec.lua
index 20f78ca8..d44772ec 100644
--- a/test/gitsigns_spec.lua
+++ b/test/gitsigns_spec.lua
@@ -83,18 +83,18 @@ describe('gitsigns', function()
     -- Don't set this too low, or else the test will lock up
     config.watch_gitdir = {interval = 100}
     setup_gitsigns(config)
+    command('Gitsigns clear_debug')
     edit(test_file)
 
     expectf(function()
       match_dag(debug_messages(), {
-        p'run_job: git .* %-%-version',
-        'attach(1): Attaching (trigger=BufRead)',
+        'attach(1): Attaching (trigger=BufReadPost)',
         p'run_job: git .* config user.name',
         p'run_job: git .* rev%-parse %-%-show%-toplevel %-%-absolute%-git%-dir %-%-abbrev%-ref HEAD',
         p('run_job: git .* ls%-files %-%-stage %-%-others %-%-exclude%-standard %-%-eol '..helpers.pesc(test_file)),
         'watch_gitdir(1): Watching git dir',
         p'run_job: git .* show :0:dummy.txt',
-        'update(1): updates: 1, jobs: 7'
+        'update(1): updates: 1, jobs: 6'
       })
     end)
 
@@ -118,7 +118,7 @@ describe('gitsigns', function()
     edit(tmpfile)
 
     match_debug_messages {
-      'attach(1): Attaching (trigger=BufRead)',
+      'attach(1): Attaching (trigger=BufReadPost)',
       p'run_job: git .* config user.name',
       p'run_job: git .* rev%-parse %-%-show%-toplevel %-%-absolute%-git%-dir %-%-abbrev%-ref HEAD',
       'new: Not in git repo',
@@ -167,7 +167,7 @@ describe('gitsigns', function()
       edit(scratch..'/.git/index')
 
       match_debug_messages {
-        'attach(1): Attaching (trigger=BufRead)',
+        'attach(1): Attaching (trigger=BufReadPost)',
         'new: In git dir',
         'attach(1): Empty git obj'
       }
@@ -183,7 +183,7 @@ describe('gitsigns', function()
       edit(ignored_file)
 
       match_debug_messages {
-        'attach(1): Attaching (trigger=BufRead)',
+        'attach(1): Attaching (trigger=BufReadPost)',
         p'run_job: git .* config user.name',
         p'run_job: git .* rev%-parse %-%-show%-toplevel %-%-absolute%-git%-dir %-%-abbrev%-ref HEAD',
         p'run_job: git .* ls%-files .*/dummy_ignored.txt',
@@ -225,7 +225,7 @@ describe('gitsigns', function()
       command("Gitsigns clear_debug")
       command("copen")
       match_debug_messages {
-        'attach(2): Attaching (trigger=BufRead)',
+        'attach(2): Attaching (trigger=BufReadPost)',
         'attach(2): Non-normal buffer',
       }
     end)
@@ -349,7 +349,7 @@ describe('gitsigns', function()
 
       edit(test_file)
       match_debug_messages {
-        'attach(1): Attaching (trigger=BufRead)',
+        'attach(1): Attaching (trigger=BufReadPost)',
         p'run_job: git .* config user.name',
         p'run_job: git .* rev%-parse %-%-show%-toplevel %-%-absolute%-git%-dir %-%-abbrev%-ref HEAD',
         p'run_job: git .* rev%-parse %-%-short HEAD',
@@ -484,7 +484,7 @@ describe('gitsigns', function()
           table.insert(messages, p'run_job: git .* diff .* /tmp/lua_.* /tmp/lua_.*')
         end
 
-        local jobs = internal_diff and 9 or 10
+        local jobs = internal_diff and 8 or 9
         table.insert(messages, "update(1): updates: 1, jobs: "..jobs)
 
         match_debug_messages(messages)
diff --git a/test/gs_helpers.lua b/test/gs_helpers.lua
index 42ad4d65..95ee0428 100644
--- a/test/gs_helpers.lua
+++ b/test/gs_helpers.lua
@@ -21,6 +21,7 @@ M.newfile   = M.scratch.."/newfile.txt"
 
 M.test_config = {
   debug_mode = true,
+  _test_mode = true,
   signs = {
     add          = {hl = 'DiffAdd'   , text = '+'},
     delete       = {hl = 'DiffDelete', text = '_'},
@@ -47,15 +48,6 @@ local test_file_text = {
   'content', 'doesn\'t', 'matter,', 'it', 'just', 'needs', 'to', 'be', 'static.'
 }
 
---- Escapes magic chars in |lua-patterns|.
----
----@see https://github.com/rxi/lume
----@param s string String to escape
----@return string %-escaped pattern string
-function M.pesc(s)
-  return (s:gsub('[%(%)%.%%%+%-%*%?%[%]%^%$]', '%%%1'))
-end
-
 function M.git(args)
   system{"git", "-C", M.scratch, unpack(args)}
 end
@@ -64,7 +56,6 @@ function M.cleanup()
   system{"rm", "-rf", M.scratch}
 end
 
-
 function M.setup_git()
   M.git{"init", '-b', 'master'}
 
@@ -105,7 +96,8 @@ function M.expectf(cond, interval)
   local duration = 0
   interval = interval or 1
   while duration < timeout do
-    if pcall(cond) then
+    local ok, ret = pcall(cond)
+    if ok and (ret == nil or ret == true) then
       return
     end
     duration = duration + interval
@@ -124,7 +116,7 @@ function M.edit(path)
 end
 
 function M.write_to_file(path, text)
-  local f = io.open(path, 'wb')
+  local f = assert(io.open(path, 'wb'))
   for _, l in ipairs(text) do
     f:write(l)
     f:write('\n')
@@ -132,6 +124,13 @@ function M.write_to_file(path, text)
   f:close()
 end
 
+local function spec_text(s)
+  if type(s) == 'table' then
+    return s.text
+  end
+  return s
+end
+
 function M.match_lines(lines, spec)
   local i = 1
   for lid, line in ipairs(lines) do
@@ -153,12 +152,13 @@ function M.match_lines(lines, spec)
       i = i + 1
     end
   end
+
   if i < #spec + 1 then
     local msg = {'lines:'}
     for _, l in ipairs(lines) do
-      msg[#msg+1] = string.format(   '"%s"', l)
+      msg[#msg+1] = string.format('    - "%s"', l)
     end
-    error(('Did not match pattern \'%s\' with %s'):format(spec[i], table.concat(msg, '\n')))
+    error(('Did not match pattern \'%s\' with %s'):format(spec_text(spec[i]), table.concat(msg, '\n')))
   end
 end
 
@@ -209,7 +209,7 @@ function M.n(str)
 end
 
 function M.debug_messages()
-  return exec_lua("return require'gitsigns'.debug_messages(true)")
+  return exec_lua("return require'gitsigns.debug.log'.messages")
 end
 
 function M.match_dag(lines, spec)
@@ -224,6 +224,8 @@ function M.match_debug_messages(spec)
   end)
 end
 
+local git_version
+
 function M.setup_gitsigns(config, extra)
   extra = extra or ''
   exec_lua([[
@@ -232,7 +234,7 @@ function M.setup_gitsigns(config, extra)
       require('gitsigns').setup(...)
     ]], config)
   M.expectf(function()
-    exec_capture('au gitsigns')
+    return exec_lua[[return require'gitsigns'._setup_done == true]]
   end)
 end
 
diff --git a/test/highlights_spec.lua b/test/highlights_spec.lua
index 63f0c160..7cb73762 100644
--- a/test/highlights_spec.lua
+++ b/test/highlights_spec.lua
@@ -58,6 +58,7 @@ describe('highlights', function()
     config.signs.topdelete.hl = nil
     config.numhl = true
     config.linehl = true
+    config._test_mode = true
 
     exec_lua('gs.setup(...)', config)
 
diff --git a/types/vim.d.tl b/types/vim.d.tl
index 964f94a2..ed65aa45 100644
--- a/types/vim.d.tl
+++ b/types/vim.d.tl
@@ -226,6 +226,10 @@ local record M
   end
 
   is_thread: function(): boolean
+
+  record fs
+    find: function(string|{string}, table): {string}
+  end
 end
 
 return M
diff --git a/types/vim/api.d.tl b/types/vim/api.d.tl
index e100f012..2cbf6d42 100644
--- a/types/vim/api.d.tl
+++ b/types/vim/api.d.tl
@@ -92,7 +92,16 @@ local record M
   nvim_create_augroup: function(string, AugroupOpts): integer
 
   record AutoCmdOpts
-    callback: function()
+    record CallbackData
+      id: integer
+      group: integer
+      event: string
+      match: string
+      buf: integer
+      file: string
+      data: any
+    end
+    callback: function(CallbackData)
     command: string
     group: integer|string
     pattern: string|{string}