[idea] Per-project session persistence via :mksession / SessionLoadPost #171

What

Automatically save and restore the window layout, open buffers, and LCD working directory per git root using Neovim's built-in :mksession. Session file is keyed to the git root path so each project gets its own saved state.

Where

New autocmd block in lua/config/options.lua (near the existing vim.g.netrw_keepdir line), or a new lua/config/session.lua module loaded from init.lua.

Why it matters

server.lua handles connecting to live Neovim instances, but nothing survives a full restart (:ZR, crash, system reboot). After a restart, all window splits, open files, and lcd state are gone. Given that the config:

• relies on lcd-based project roots ([idea] Auto-lcd to git root on file open #165)
• spins up multiple LSP clients per buffer (which take a moment to attach)
• uses custom folds (treesitter foldexpr)

…restoring a prior session eliminates the friction of re-opening files and waiting for LSPs to attach.

Suggested implementation

local function session_file()
    local git_root = vim.fn.finddir(".git", ".;")
    if git_root == "" then return nil end
    local dir = vim.fn.fnamemodify(git_root, ":p:h")
    local encoded = dir:gsub("[/\\]", "%%")
    vim.fn.mkdir(vim.fn.stdpath("data") .. "/sessions", "p")
    return vim.fn.stdpath("data") .. "/sessions/" .. encoded .. ".vim"
end

-- Save on exit
vim.api.nvim_create_autocmd("VimLeavePre", {
    callback = function()
        local f = session_file()
        if f then vim.cmd("mksession! " .. vim.fn.fnameescape(f)) end
    end,
})

-- Restore on startup (only if no files were given on the CLI)
if vim.fn.argc() == 0 then
    vim.api.nvim_create_autocmd("VimEnter", {
        once = true,
        callback = function()
            local f = session_file()
            if f and vim.fn.filereadable(f) == 1 then
                vim.cmd("source " .. vim.fn.fnameescape(f))
            end
        end,
    })
end

Pairs with #165 (auto-lcd): if cwd is always the git root on BufEnter, the session file lookup is stable across working-directory changes.