wezterm.lua

local function getLastDirectory(fullPath)
	-- Replace "file:////" with an empty string to remove it from the path
	local cleanPath = string.gsub(fullPath, "file:////", "")

	-- Separate the path using the directory separator "/"
	local directories = {}
	for directory in string.gmatch(cleanPath, "[^/]+") do
		table.insert(directories, directory)
	end

	-- Return the last directory
	if #directories > 0 then
		return directories[#directories]
	else
		return nil
	end
end

wezterm.on("format-tab-title", function(tab)
	local pane = tab.active_pane
	local cwd = pane.current_working_dir
	local title = string.format("%s:%s", tab.tab_index + 1, getLastDirectory(cwd))

	return {
		{ Text = " " .. title .. " " },
	}
end)