[idea] Auto-create parent directories on BufWritePre

[stanfish06]

What

Add a BufWritePre autocmd that creates any missing parent directories before saving, so :e some/new/path/file.lua followed by :w succeeds instead of erroring with E212: Can't open file for writing.

Where

lua/config/options.lua — near the other BufWritePre logic, or as a new autocmd group.

Why it matters

The current config already edits files via :e **/* wildcards (<leader>e) and opens new buffers with <leader>bn. It's a common workflow to open a new file inside a directory that doesn't exist yet, especially when sketching out new module structures. Without this autocmd, every such save requires a manual !mkdir -p %:h first.

Recommended implementation

vim.api.nvim_create_autocmd("BufWritePre", {
    group = vim.api.nvim_create_augroup("AutoMkdir", { clear = true }),
    callback = function(ev)
        if ev.match:match("^%a+://") then return end  -- skip remote/oil buffers
        local dir = vim.fn.fnamemodify(ev.match, ":p:h")
        if vim.fn.isdirectory(dir) == 0 then
            vim.fn.mkdir(dir, "p")
        end
    end,
})

The %a+:// guard prevents it from running on oil://, fugitive://, or other virtual buffers whose names look like paths but aren't.

This pairs naturally with the existing BufWritePre formatting autocmd in plugin_config.lua (lines 190–196).