diff --git a/init.lua b/init.lua
index 07896a8..ecff2c3 100644
--- a/init.lua
+++ b/init.lua
@@ -38,6 +38,7 @@ vim.loader.enable()
 -- load configuration
 require("config.ui")
 require("config.options")
+require("config.diagnostic")
 require("config.treesitter")
 require("config.autocommands")
 require("config.keymaps")
diff --git a/lua/config/diagnostic.lua b/lua/config/diagnostic.lua
new file mode 100644
index 0000000..ca881e3
--- /dev/null
+++ b/lua/config/diagnostic.lua
@@ -0,0 +1,88 @@
+
+--[[
+
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⣴⣾⣷⣦⣄⡀
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⣴⣾⣿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣄⡀
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⣴⣾⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣄⡀
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡀⠚⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⠗⢀
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣤⣄⡉⠓⠦⣌⡙⠻⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⠟⢋⣡⠴⠚⢉⣠⣤⣀
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣤⣶⣿⣿⣿⣿⣿⣷⣦⣄⡉⠓⠦⣌⡙⠻⢿⣿⣿⣿⣿⣿⣿⡿⠟⢋⣡⠴⠚⢉⣠⣴⣾⣿⣿⣿⣿⣿⣶⣤
+⠀⠀⠀⠀⠀⠀⠀⠀⠐⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠓⠦⣌⡙⠻⠟⢋⣡⠴⠚⢉⣠⣴⣾⣿⣿⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⠂
+⠀⠀⠀⠀⢀⣠⣴⣆⡈⠻⢿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠃⠘⢉⣠⣴⣾⣿⣿⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⡿⠟⢁⣰⣦⣄⡀
+⠀⠀⠐⠾⣿⣿⣿⣿⣿⣷⣦⣌⡙⠻⢿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣿⣿⣷⣾⣿⣿⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⡿⠟⢋⣡⣴⣾⣿⣿⣿⣿⣿⠷⠂
+⠀⢸⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣌⡙⠻⢿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⡿⠟⢋⣡⣴⣾⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⡇
+⠀⢸⣿⣿⣿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣌⡙⠻⢿⣿⣷⣦⣄⡉⠛⠿⠿⠛⢉⣠⣴⣾⣿⡿⠟⢋⣡⣴⣾⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⣿⣿⣿⡇
+⠀⠀⠉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣌⡙⠻⢿⣿⣷⡆⢰⣾⣿⡿⠟⢋⣡⣴⣾⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣌⡙⠃⠘⢋⣡⣴⣾⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⣿⣷⣾⣿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣄⡉⠛⠿⣿⣿⣿⣿⠿⠛⢉⣠⣴⣾⣿⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣿⣿⣿⣿⣷⣦⣄⡉⢉⣠⣴⣾⣿⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣿⣿⣿⡇⢸⣿⣿⣿⣿⠿⠛⠉
+⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⡇⢸⠿⠛⠉
+
+              __             _             _
+             / _|___     ___| |_ __ _  ___| | __
+            | ||_  /____/ __| __/ _` |/ __| |/ /
+            |  _/ /_____\__ \ || (_| | (__|   <
+            |_|/___|    |___/\__\__,_|\___|_|\_\
+
+                Neovim 0.12 configuration
+                  (c) Frank Zechert 2026
+]]
+
+vim.diagnostic.config({
+	update_in_insert = false,
+	severity_sort = true,
+	float = {
+		border = vim.g.ui.border,
+		source = true,
+	},
+	underline = true,
+	-- underline = { severity = { min = vim.diagnostic.severity.WARN } },
+	virtual_text = {
+		prefix = vim.g.ui.symbols.diagnostic.virtual_text_prefix,
+		severity = nil, -- show all severity
+		spacing = 2, -- extra spacing between text and code
+		virt_text_pos = "eol",
+		source = "if_many",
+		format = function(diagnostic) -- Customize the text shown in virtual text
+			local severity = vim.diagnostic.severity[diagnostic.severity]
+			local symbols = {
+				ERROR = vim.g.ui.symbols.diagnostic.sign_error,
+				WARN = vim.g.ui.symbols.diagnostic.sign_warn,
+				INFO = vim.g.ui.symbols.diagnostic.sign_info,
+				HINT = vim.g.ui.symbols.diagnostic.sign_hint,
+			}
+			return string.format("%s", diagnostic.message)
+		end,
+
+	},
+	virtual_lines = false,
+	jump = {
+		on_jump = function(_, bufnr)
+			vim.diagnostic.open_float({
+				bufnr = bufnr,
+				scope = 'cursor',
+				focus = false
+			})
+		end,
+	},
+	signs = {
+		-- icons in sign column
+		text = {
+			[vim.diagnostic.severity.ERROR] = vim.g.ui.symbols.diagnostic.sign_error,
+			[vim.diagnostic.severity.WARN] = vim.g.ui.symbols.diagnostic.sign_warn,
+			[vim.diagnostic.severity.INFO] = vim.g.ui.symbols.diagnostic.sign_info,
+			[vim.diagnostic.severity.HINT] = vim.g.ui.symbols.diagnostic.sign_hint,
+		},
+		-- highlight line
+		linehl = {
+			-- [vim.diagnostic.severity.ERROR] = "ErrorMsg",
+		},
+		-- diagnostic sign priority
+		priority = 20,
+	}
+
+})
+
+vim.keymap.set("n", "<leader>q", vim.diagnostic.setloclist, { desc = "Open Diagnostic Quickfix List" })
diff --git a/lua/config/ui.lua b/lua/config/ui.lua
index 7c532f5..0165f84 100644
--- a/lua/config/ui.lua
+++ b/lua/config/ui.lua
@@ -64,6 +64,13 @@ vim.g.ui = {
 		component_separators = { left = "│", right = "│" },
 		section_separators = { left = "▒", right = "▒" },
 		window = "",
+		diagnostic = {
+			prefix = "■",
+			sign_error = "E",
+			sign_warn = "W",
+			sign_info = "I",
+			sign_hint = "H",
+		},
 		git = {
 			signs = {
 				add = { text = "┃" },