diff --git a/.luarc.json b/.luarc.json
index 23646d3..3f6276a 100644
--- a/.luarc.json
+++ b/.luarc.json
@@ -2,7 +2,13 @@
   "runtime.version": "LuaJIT",
   "runtime.path": ["lua/?.lua", "lua/?/init.lua"],
   "diagnostics.globals": ["vim", "jit"],
-  "workspace.library": ["$VIMRUNTIME/lua", "${3rd}/luv/library"],
+  "workspace.library": [
+    "$VIMRUNTIME/lua",
+    "${3rd}/luv/library",
+    "${3rd}/busted/library",
+    "${3rd}/luassert/library"
+  ],
   "workspace.checkThirdParty": false,
+  "workspace.ignoreDir": [".direnv"],
   "completion.callSnippet": "Replace"
 }
diff --git a/.styluaignore b/.styluaignore
new file mode 100644
index 0000000..9b42106
--- /dev/null
+++ b/.styluaignore
@@ -0,0 +1 @@
+.direnv/
diff --git a/flake.nix b/flake.nix
index 7413113..0243f3e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -16,6 +16,8 @@
       forEachSystem = f: nixpkgs.lib.genAttrs (import systems) (system: f nixpkgs.legacyPackages.${system});
     in
     {
+      formatter = forEachSystem (pkgs: pkgs.nixfmt-tree);
+
       devShells = forEachSystem (pkgs: {
         default = pkgs.mkShell {
           packages = [
diff --git a/scripts/ci.sh b/scripts/ci.sh
new file mode 100755
index 0000000..e06bf09
--- /dev/null
+++ b/scripts/ci.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+set -eu
+
+nix develop --command stylua --check .
+git ls-files '*.lua' | xargs nix develop --command selene --display-style quiet
+nix develop --command prettier --check .
+nix fmt
+git diff --exit-code -- '*.nix'
+nix develop --command lua-language-server --check . --checklevel=Warning
+nix develop --command busted