feat(nvim): add copy_ref plugin for AI chat references

Adds a scratch buffer-based utility to copy file paths and line
ranges for pasting into AI chat conversations. Supports normal mode
(copy path), visual mode (copy path:start:end), and a scratch buffer
for collecting multiple references.

config/mini.nvim/plugin/copy_ref.lua

@@ -0,0 +1,131 @@
+-- from smnatale's github.com/smnatale/nvim-config
+--
+-- Copy file path / selection reference for pasting into AI chats
+
+local scratch_buf = nil
+local scratch_buf_name = "copy-refs"
+
+local function get_or_create_scratch()
+	-- if we already created a buffer and it's still valid, reuse it
+	if scratch_buf and vim.api.nvim_buf_is_valid(scratch_buf) then
+		return scratch_buf
+	end
+
+    -- look for an existing buffer by name
+    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
+        if vim.api.nvim_buf_is_valid(buf) then
+            local name = vim.api.nvim_buf_get_name(buf)
+            if name:match("/" .. scratch_buf_name .. "$") or name == scratch_buf_name then
+                scratch_buf = buf
+                return scratch_buf
+            end
+        end
+    end
+
+    -- create a new unlisted scratch buffer
+    scratch_buf = vim.api.nvim_create_buf(false, true)
+    vim.api.nvim_buf_set_name(scratch_buf, scratch_buf_name)
+    vim.bo[scratch_buf].buftype = "nofile"
+    vim.bo[scratch_buf].bufhidden = "hide"
+    vim.bo[scratch_buf].swapfile = false
+
+	return scratch_buf
+end
+
+local function open_scratch()
+		local buf = get_or_create_scratch()
+		local width = math.floor(vim.o.columns * 0.8)
+		local height = math.floor(vim.o.lines * 0.8)
+		local row = math.floor((vim.o.lines - height) / 2)
+		local col = math.floor((vim.o.columns - width) / 2)
+		local _ = vim.api.nvim_open_win(buf, true, {
+			relative = "editor",
+			width = width,
+			height = height,
+			row = row,
+			col = col,
+			style = "minimal",
+			border = "rounded",
+		})
+		vim.api.nvim_buf_set_keymap(buf, "n", "q", ":close<CR>", { noremap = true, silent = true })
+end
+
+local function copy_ref(opts)
+	-- "%" is the current buffer's file name; ":." makes it relative to the cwd
+	local path = vim.fn.expand("%:.")
+	-- ref is what ends up in the clipboard; start with just the path
+	local ref = path
+
+	if opts.visual then
+		-- '< and '> are only set after leaving visual mode, so read the live selection:
+		-- "v" is the line where visual mode was started (the anchor)
+		local start_line = vim.fn.line("v")
+		-- "." is the line the cursor is on now (the moving end of the selection)
+		local end_line = vim.fn.line(".")
+		-- if the selection was made upward, swap so start is always the smaller line
+		if start_line > end_line then
+			start_line, end_line = end_line, start_line
+		end
+		-- append the range, e.g. "lua/config/keymaps.lua:1:23"
+		ref = path .. ":" .. start_line .. ":" .. end_line
+	end
+
+	-- ask for an optional free-text note on the command line (Enter to skip)
+	local note = vim.fn.input("Prompt (optional): ")
+	if note ~= "" then
+		-- append the note after the ref, separated by a space
+		ref = ref .. " " .. note
+	end
+
+	-- write ref into the "+" register, which is the system clipboard
+	vim.fn.setreg("+", ref)
+
+	-- append to scratch buffer
+	local buf = get_or_create_scratch()
+	local lines = vim.api.nvim_buf_get_lines(buf, 0, -1, false)
+	local insert_pos = #lines
+	if insert_pos > 0 and lines[insert_pos] ~= "" then
+		vim.api.nvim_buf_set_lines(buf, insert_pos, insert_pos, false, { "", ref })
+	else
+		vim.api.nvim_buf_set_lines(buf, insert_pos, insert_pos, false, { ref })
+	end
+
+	-- clear visual selection if we were in visual mode
+	if opts.visual then
+		vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes("<Esc>", true, false, true), "n", false)
+	end
+
+	-- show a confirmation message with what was copied
+	vim.notify("Copied: " .. ref)
+end
+
+-- normal mode: copy just the file path
+vim.keymap.set("n", "<leader>bc", function()
+	copy_ref({})
+end, { desc = "Copy file path" })
+
+-- visual mode: copy the file path plus the selected line range
+vim.keymap.set("v", "<leader>bc", function()
+	copy_ref({ visual = true })
+end, { desc = "Copy file path with line range" })
+
+-- open the copy-ref scratch buffer 
+vim.keymap.set("n", "<leader>b.", function()
+	open_scratch()
+end, { desc = "Open copy-ref scratch buffer" })
+
+-- clear the copy-ref scratch buffer
+vim.keymap.set("n", "<leader>bx", function()
+	local buf = get_or_create_scratch()
+	vim.api.nvim_buf_set_lines(buf, 0, -1, false, {})
+	vim.notify("Cleared copy-refs buffer")
+end, { desc = "Clear copy-ref scratch buffer" })
+
+-- yank the entire copy-ref scratch buffer into the + register
+vim.keymap.set("n", "<leader>by", function()
+	local buf = get_or_create_scratch()
+	local lines = vim.api.nvim_buf_get_lines(buf, 0, -1, false)
+	local content = table.concat(lines, "\n")
+	vim.fn.setreg("+", content)
+	vim.notify("Yanked copy-refs buffer (" .. #lines .. " lines)")
+end, { desc = "Yank copy-ref scratch buffer" })