improve notes workflow and macOS shell setup

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;

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

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
 

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,
   },
 }