diff --git a/.emmyrc.json b/.emmyrc.json
new file mode 100644
index 0000000..36adf7e
--- /dev/null
+++ b/.emmyrc.json
@@ -0,0 +1,17 @@
+{
+  "$schema": "https://raw.githubusercontent.com/EmmyLuaLs/emmylua-analyzer-rust/refs/heads/main/crates/emmylua_code_analysis/resources/schema.json",
+  "diagnostics": {
+    "enable": true,
+    "globals": ["vim", "it", "describe", "before_each", "after_each"]
+  },
+  "runtime": {
+    "version": "LuaJIT"
+  },
+  "workspace": {
+    "library": [
+      "$VIMRUNTIME",
+      "library/busted",
+      "library/luassert"
+    ]
+  }
+}
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..435ce42
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,20 @@
+; [submodule "library/busted"]
+; 	path = library/busted
+; 	url = https://github.com/LuaCATS/busted
+; 	branch = main
+; [submodule "library/luassert"]
+; 	path = library/luassert
+; 	url = https://github.com/LuaCATS/luassert
+; 	branch = main
+; [submodule "library/luv"]
+; 	path = library/luv
+; 	url = https://github.com/LuaCATS/luv
+; 	branch = main
+[submodule "library/busted"]
+	path = library/busted
+	url = https://github.com/LuaCATS/busted
+	branch = main
+[submodule "library/luassert"]
+	path = library/luassert
+	url = https://github.com/LuaCATS/luassert
+	branch = main
diff --git a/.luacheckrc b/.luacheckrc
deleted file mode 100644
index 8317fde..0000000
--- a/.luacheckrc
+++ /dev/null
@@ -1,2 +0,0 @@
--- :vim set ft=lua
-globals = { "vim" }
diff --git a/Makefile b/Makefile
index 4e5b84f..2779587 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,10 @@
+export VIMRUNTIME := $(shell nvim -u NORC --headless +'echo $$VIMRUNTIME' +'quitall' 2>&1)
+
 all: lint fmt-check test
 
 lint:
 	@echo "## Typechecking"
-	@lua-language-server --check=lua/u/ --checklevel=Error
+	@emmylua_check .
 
 fmt-check:
 	@echo "## Checking code format"
diff --git a/examples/filetree.lua b/examples/filetree.lua
index ed175b0..7c49165 100644
--- a/examples/filetree.lua
+++ b/examples/filetree.lua
@@ -10,8 +10,8 @@
 --   change on the underlying filesystem.
 --------------------------------------------------------------------------------
 
---- @alias u.examples.FsDir { kind: 'dir'; path: string; expanded: boolean; children: u.examples.FsNode[] }
---- @alias u.examples.FsFile { kind: 'file'; path: string }
+--- @alias u.examples.FsDir { kind: 'dir', path: string, expanded: boolean, children: u.examples.FsNode[] }
+--- @alias u.examples.FsFile { kind: 'file', path: string }
 --- @alias u.examples.FsNode u.examples.FsDir | u.examples.FsFile
 --- @alias u.examples.ShowOpts { root_path?: string, width?: number, focus_path?: string }
 
@@ -58,7 +58,7 @@ function H.relative(path, base)
 end
 
 --- @param root_path string
---- @return { tree: u.examples.FsDir; path_to_node: table<string, u.examples.FsNode> }
+--- @return { tree: u.examples.FsDir, path_to_node: table<string, u.examples.FsNode> }
 function H.get_tree_inf(root_path)
   logger:info { 'get_tree_inf', root_path }
   --- @type table<string, u.examples.FsNode>
@@ -113,10 +113,10 @@ function H.populate_dir_children(tree, path_to_node)
 end
 
 --- @param opts {
----   bufnr: number;
----   prev_winnr: number;
----   root_path: string;
----   focus_path?: string;
+---   bufnr: number,
+---   prev_winnr: number,
+---   root_path: string,
+---   focus_path?: string
 --- }
 ---
 --- @return { expand: fun(path: string), collapse: fun(path: string) }
@@ -310,7 +310,7 @@ local function _render_in_buffer(opts)
   --
   local renderer = Renderer.new(opts.bufnr)
   tracker.create_effect(function()
-    --- @type { tree: u.examples.FsDir; path_to_node: table<string, u.examples.FsNode> }
+    --- @type { tree: u.examples.FsDir, path_to_node: table<string, u.examples.FsNode> }
     local tree_inf = s_tree_inf:get()
     local tree = tree_inf.tree
 
@@ -407,9 +407,9 @@ end
 --------------------------------------------------------------------------------
 
 --- @type {
----   bufnr: number;
----   winnr: number;
----   controller: { expand: fun(path: string), collapse: fun(path: string) };
+---   bufnr: number,
+---   winnr: number,
+---   controller: { expand: fun(path: string), collapse: fun(path: string) }
 --- } | nil
 local current_inf = nil
 
diff --git a/examples/notify.lua b/examples/notify.lua
index bce6db3..3ec68c7 100644
--- a/examples/notify.lua
+++ b/examples/notify.lua
@@ -23,10 +23,10 @@ vim.api.nvim_create_autocmd('VimResized', {
 })
 
 --- @alias u.examples.Notification {
----   kind: number;
----   id: number;
----   text: string;
----   timer: uv.uv_timer_t;
+---   kind: number,
+---   id: number,
+---   text: string,
+---   timer: uv.uv_timer_t
 --- }
 
 local M = {}
diff --git a/examples/picker.lua b/examples/picker.lua
index 1075f46..6f72eba 100644
--- a/examples/picker.lua
+++ b/examples/picker.lua
@@ -44,22 +44,22 @@ local function shallow_copy_arr(arr) return vim.iter(arr):totable() end
 --    shortest portion of this function.
 --------------------------------------------------------------------------------
 
---- @alias u.examples.SelectController {
----   get_items: fun(): T[];
----   set_items: fun(items: T[]);
----   set_filter_text: fun(filter_text: string);
----   get_selected_indices: fun(): number[];
----   get_selected_items: fun(): T[];
----   set_selected_indices: fun(indicies: number[], ephemeral?: boolean);
----   close: fun();
+--- @alias u.examples.SelectController<T> {
+---   get_items: fun(): T[],
+---   set_items: fun(items: T[]),
+---   set_filter_text: fun(filter_text: string),
+---   get_selected_indices: fun(): number[],
+---   get_selected_items: fun(): T[],
+---   set_selected_indices: fun(indicies: number[], ephemeral?: boolean),
+---   close: fun()
 --- }
 --- @alias u.examples.SelectOpts<T> {
----   items: `T`[];
----   multi?: boolean;
----   format_item?: fun(item: T): u.renderer.Tree;
----   on_finish?: fun(items: T[], indicies: number[]);
----   on_selection_changed?: fun(items: T[], indicies: number[]);
----   mappings?: table<string, fun(select: u.examples.SelectController)>;
+---   items: `T`[],
+---   multi?: boolean,
+---   format_item?: (fun(item: T): u.renderer.Tree),
+---   on_finish?: (fun(items: T[], indicies: number[])),
+---   on_selection_changed?: fun(items: T[], indicies: number[]),
+---   mappings?: table<string, fun(select: u.examples.SelectController)>
 --- }
 
 --- @generic T
@@ -326,7 +326,7 @@ function M.create_picker(opts) -- {{{
     safe_wrap(function()
       local items = s_items:get()
       local selected_indices = s_selected_indices:get()
-      --- @type { orig_idx: number; item: T }[]
+      --- @type { orig_idx: number, item: T }[]
       local filtered_items = s_filtered_items:get()
       local cursor_index = s_cursor_index:get()
       local indices = shallow_copy_arr(selected_indices)
@@ -477,7 +477,7 @@ function M.create_picker(opts) -- {{{
       local selected_indices = s_selected_indices:get()
       local top_offset = s_top_offset:get()
       local cursor_index = s_cursor_index:get()
-      --- @type { filtered_idx: number; orig_idx: number; item: T; formatted: string }[]
+      --- @type { filtered_idx: number, orig_idx: number, item: T, formatted: string }[]
       local visible_items = s_visible_items:get()
 
       -- The above has to run in the execution context for the signaling to work, but
@@ -791,14 +791,14 @@ function M.buffers() -- {{{
   -- ensure that `cwd` ends with a trailing slash:
   if cwd[#cwd] ~= '/' then cwd = cwd .. '/' end
 
-  --- @type { name: string; changed: number; bufnr: number }[]
+  --- @type { name: string, changed: number, bufnr: number }[]
   local bufs = vim.fn.getbufinfo { buflisted = 1 }
 
   M.create_picker {
     multi = true,
     items = bufs,
 
-    --- @param item { name: string; changed: number; bufnr: number }
+    --- @param item { name: string, changed: number, bufnr: number }
     format_item = function(item)
       local item_name = item.name
       if item_name == '' then item_name = '[No Name]' end
diff --git a/examples/surround.lua b/examples/surround.lua
index 1b1c1fc..db4aa31 100644
--- a/examples/surround.lua
+++ b/examples/surround.lua
@@ -21,10 +21,10 @@ local surrounds = {
   ['`'] = { left = '`', right = '`' },
 }
 
---- @type { left: string; right: string } | nil
+--- @type { left: string, right: string } | nil
 local CACHED_BOUNDS = nil
 
---- @return { left: string; right: string }|nil
+--- @return { left: string, right: string }|nil
 local function prompt_for_bounds()
   if vim_repeat.is_repeating() then
     -- If we are repeating, we don't want to prompt for bounds, because
@@ -55,7 +55,7 @@ local function prompt_for_bounds()
 end
 
 --- @param range u.Range
---- @param bounds { left: string; right: string }
+--- @param bounds { left: string, right: string }
 local function do_surround(range, bounds)
   local left = bounds.left
   local right = bounds.right
diff --git a/library/busted b/library/busted
new file mode 160000
index 0000000..5ed85d0
--- /dev/null
+++ b/library/busted
@@ -0,0 +1 @@
+Subproject commit 5ed85d0e016a5eb5eca097aa52905eedf1b180f1
diff --git a/library/luassert b/library/luassert
new file mode 160000
index 0000000..d3528bb
--- /dev/null
+++ b/library/luassert
@@ -0,0 +1 @@
+Subproject commit d3528bb679302cbfdedefabb37064515ab95f7b9
diff --git a/lua/u/buffer.lua b/lua/u/buffer.lua
index b380a61..f27f5c0 100644
--- a/lua/u/buffer.lua
+++ b/lua/u/buffer.lua
@@ -62,7 +62,7 @@ end
 function Buffer:lines(start, stop) return Range.from_lines(self.bufnr, start, stop) end
 
 --- @param motion string
---- @param opts? { contains_cursor?: boolean; pos?: u.Pos }
+--- @param opts? { contains_cursor?: boolean, pos?: u.Pos }
 function Buffer:motion(motion, opts)
   opts = vim.tbl_extend('force', opts or {}, { bufnr = self.bufnr })
   return Range.from_motion(motion, opts)
diff --git a/lua/u/opkeymap.lua b/lua/u/opkeymap.lua
index 0942495..282727e 100644
--- a/lua/u/opkeymap.lua
+++ b/lua/u/opkeymap.lua
@@ -5,7 +5,6 @@ local __U__OpKeymapOpFunc_rhs = nil
 
 --- This is the global utility function used for operatorfunc
 --- in opkeymap
---- @type nil|fun(range: u.Range): fun():any|nil
 --- @param ty 'line'|'char'|'block'
 -- selene: allow(unused_variable)
 function _G.__U__OpKeymapOpFunc(ty)
diff --git a/lua/u/range.lua b/lua/u/range.lua
index 6baed0d..1625925 100644
--- a/lua/u/range.lua
+++ b/lua/u/range.lua
@@ -112,7 +112,7 @@ function Range.from_lines(bufnr, start_line, stop_line)
 end
 
 --- @param motion string
---- @param opts? { bufnr?: number; contains_cursor?: boolean; pos?: u.Pos, user_defined?: boolean }
+--- @param opts? { bufnr?: number, contains_cursor?: boolean, pos?: u.Pos, user_defined?: boolean }
 --- @return u.Range|nil
 function Range.from_motion(motion, opts)
   -- Options handling:
@@ -513,7 +513,7 @@ function Range:text() return vim.fn.join(self:lines(), '\n') end
 
 --- @param l number
 -- luacheck: ignore
---- @return { line: string; idx0: { start: number; stop: number; }; lnum: number; range: fun():u.Range; text: fun():string }|nil
+--- @return { line: string, idx0: { start: number, stop: number }, lnum: number, range: (fun():u.Range), text: fun():string }|nil
 function Range:line(l)
   if l < 0 then l = self:line_count() + l + 1 end
   if l > self:line_count() then return end
diff --git a/shell.nix b/shell.nix
index bb24309..fcebe49 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,10 +1,10 @@
 {
   pkgs ?
     import
-      # nixos-25.05 (neovim@0.11.2):
+      # nixos-unstable (neovim@0.11.4):
       (fetchTarball {
-        url = "https://github.com/nixos/nixpkgs/archive/1c1c9b3f5ec0421eaa0f22746295466ee6a8d48f.tar.gz";
-        sha256 = "0szvq1swpzyjmyyw929ngxy1khdnd9ba96qds2bm6l6kg4iq3cq0";
+        url = "https://github.com/nixos/nixpkgs/archive/0b4defa2584313f3b781240b29d61f6f9f7e0df3.tar.gz";
+        sha256 = "0p3rrd8wwlk0iwgzm7frkw1k98ywrh0avi7fqjjk87i68n3inxrs";
       })
       { },
 }:
@@ -12,7 +12,7 @@ pkgs.mkShell {
   packages = [
     pkgs.git
     pkgs.gnumake
-    pkgs.lua-language-server
+    pkgs.emmylua-ls
     pkgs.lua51Packages.busted
     pkgs.lua51Packages.luacov
     pkgs.lua51Packages.luarocks