diff --git a/flake.lock b/flake.lock
index b64bb8a..b3a50e3 100644
--- a/flake.lock
+++ b/flake.lock
@@ -42,15 +42,16 @@
         ]
       },
       "locked": {
-        "lastModified": 1784665499,
-        "narHash": "sha256-9BMxlTxCCDAeoNLtb1a/st7udtTIJep+wpUzquA29VU=",
-        "owner": "nix-community",
+        "lastModified": 1788011267,
+        "narHash": "sha256-mEq2kU+ljompTToZ44Afvm7d/rHJ5iMBl0tjZuyShJs=",
+        "owner": "Mic92",
         "repo": "bun2nix",
-        "rev": "0f2a1f0b6f42cebe3b149bf62d38754c5e0e9729",
+        "rev": "5765b0614591f75ee8ba5596e81ae85c167d1071",
         "type": "github"
       },
       "original": {
-        "owner": "nix-community",
+        "owner": "Mic92",
+        "ref": "fix-structured-attrs-hook",
         "repo": "bun2nix",
         "type": "github"
       }
@@ -106,11 +107,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1787559586,
-        "narHash": "sha256-onL0VLf9vPllmT0H/OlURIU5r5t5WIEl7t4tVNKT0Nw=",
+        "lastModified": 1788450739,
+        "narHash": "sha256-glZLQlzIn1fXH6PazR2iUmTo7kzzyYSshrWhLS9TqCU=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "9d0d87172c374f89da73c1cfe6d81ae62feac1f1",
+        "rev": "31729ca8cbdb4fa927b34e5f4353e6a83f39e993",
         "type": "github"
       },
       "original": {
@@ -223,11 +224,11 @@
         "treefmt-nix": "treefmt-nix"
       },
       "locked": {
-        "lastModified": 1788063845,
-        "narHash": "sha256-SdJE2vyoZJr+8iOoau7UDZAKD2hRhi51LYSBCDthiHM=",
+        "lastModified": 1788684345,
+        "narHash": "sha256-+3tYyzbgr5LdaqPDQ9tHM1JuXx7DVQqZH8MeQ7ooStI=",
         "owner": "numtide",
         "repo": "llm-agents.nix",
-        "rev": "b7e6d6d4cb01ee1bc704db8e11629adec7e2509c",
+        "rev": "76e610601903fd31e82b996b28a49c6d1adb559c",
         "type": "github"
       },
       "original": {
@@ -329,11 +330,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1787424095,
-        "narHash": "sha256-dWLO5AHhKaw6rdWCtTes8hnntT1r0/J5yhQGm0f0ZgU=",
+        "lastModified": 1788549839,
+        "narHash": "sha256-kOrCcSIA6w9J1hX5DqHy2k9pDTJymExTsbV74U9UtCA=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "174eb786fb68e3a13e4e535a3deea479a0c07a6a",
+        "rev": "17de0b976395537756f30a3e78f2f06e5cec89ed",
         "type": "github"
       },
       "original": {
diff --git a/modules/darwin/system.nix b/modules/darwin/system.nix
index 5e0f474..8d9b7ad 100644
--- a/modules/darwin/system.nix
+++ b/modules/darwin/system.nix
@@ -52,16 +52,27 @@
     XDG_CACHE_HOME = "$HOME/.cache";
   };
 
-  users.users.${user} = {
-    home = lib.mkDefault "/Users/${user}";
-    # Use the macOS system Zsh as the login shell. Nushell remains available as `nu`.
-    shell = "/bin/zsh";
-  };
+  users.users.${user}.home = lib.mkDefault "/Users/${user}";
 
   system = {
     primaryUser = user;
     stateVersion = 6;
 
+    # nix-darwin does not manage an existing primary user unless the user is in
+    # users.knownUsers. Manage only the login shell to avoid owning the account.
+    activationScripts.postActivation.text = lib.mkAfter ''
+      current_shell=$(
+        /usr/bin/dscl . -read ${lib.escapeShellArg "/Users/${user}"} UserShell 2>/dev/null \
+          | /usr/bin/awk '{ print $2 }' \
+          || true
+      )
+
+      if [ "$current_shell" != "/bin/zsh" ]; then
+        echo "setting ${user}'s login shell to /bin/zsh..." >&2
+        /usr/bin/dscl . -create ${lib.escapeShellArg "/Users/${user}"} UserShell /bin/zsh
+      fi
+    '';
+
     defaults = {
       NSGlobalDomain = {
         ApplePressAndHoldEnabled = false;
diff --git a/modules/home/programs/neovim.nix b/modules/home/programs/neovim.nix
index 1d7d1a3..62cec91 100644
--- a/modules/home/programs/neovim.nix
+++ b/modules/home/programs/neovim.nix
@@ -22,6 +22,7 @@
       pyright
       nodePackages.typescript-language-server
       mdx-language-server
+      harper # Grammar checking for Markdown and text
       rust-analyzer
       gopls
       clang-tools # provides clangd
diff --git a/modules/home/programs/nvim/lua/config/notes.lua b/modules/home/programs/nvim/lua/config/notes.lua
index faa4ab5..d2cf4e5 100644
--- a/modules/home/programs/nvim/lua/config/notes.lua
+++ b/modules/home/programs/nvim/lua/config/notes.lua
@@ -13,6 +13,31 @@ local function last_line(value)
 	return output:match("([^\r\n]+)$")
 end
 
+local function first_matching_line(value, pattern)
+	for line in (value or ""):gmatch("[^\r\n]+") do
+		local candidate = vim.trim(line)
+		if candidate:match(pattern) then
+			return candidate
+		end
+	end
+end
+
+local function first_actionable_line(value)
+	for line in (value or ""):gmatch("[^\r\n]+") do
+		local candidate = vim.trim(line)
+		if candidate ~= "" and not candidate:match("^%$ ") and not candidate:match('^error: script ".-" exited') then
+			return candidate
+		end
+	end
+end
+
+local function command_error(result)
+	return first_matching_line(result.stdout, "^ERROR%s")
+		or first_actionable_line(result.stderr)
+		or first_actionable_line(result.stdout)
+		or "Notes command failed."
+end
+
 local function run(arguments, options)
 	options = options or {}
 
@@ -39,8 +64,7 @@ local function run(arguments, options)
 		},
 		vim.schedule_wrap(function(result)
 			if result.code ~= 0 then
-				local message = last_line(result.stderr) or last_line(result.stdout) or "Notes command failed."
-				notify(message, vim.log.levels.ERROR)
+				notify(command_error(result), vim.log.levels.ERROR)
 				return
 			end
 
diff --git a/modules/home/programs/nvim/lua/plugins/lsp.lua b/modules/home/programs/nvim/lua/plugins/lsp.lua
index 7b8df34..18a7a62 100644
--- a/modules/home/programs/nvim/lua/plugins/lsp.lua
+++ b/modules/home/programs/nvim/lua/plugins/lsp.lua
@@ -106,6 +106,31 @@ return {
       lspconfig.mdx_analyzer.setup({
         capabilities = capabilities,
       })
+
+      -- Harper grammar checking for prose. Keep the profile quiet so it does
+      -- not enforce capitalization, spelling, sentence length, or house style.
+      lspconfig.harper_ls.setup({
+        capabilities = capabilities,
+        filetypes = { "markdown", "text" },
+        settings = {
+          ["harper-ls"] = {
+            diagnosticSeverity = "hint",
+            linters = {
+              AvoidContractions = false,
+              AvoidCurses = false,
+              Cant = false,
+              CapitalizePersonalPronouns = false,
+              GoogleNames = false,
+              LongSentences = false,
+              OrthographicConsistency = false,
+              OxfordComma = false,
+              SentenceCapitalization = false,
+              SpellCheck = false,
+              UseTitleCase = false,
+            },
+          },
+        },
+      })
     end,
   },
 }