1function M.append_output_cell(lines)
2    if not M.output_buf_valid() then return end
3
4    local buf = M.repl.output_buf
5    local prompt_content = M.get_last_line() or ""
6    -- Filter out echoed input (lines that match what we just sent)
7    local filtered = {}
8    for i, line in ipairs(lines) do
9        -- Skip lines that look like raw echoed input
10        if i == 1 and prompt_content:match("^i%d+ :") then
11            table.insert(filtered, prompt_content .. line)
12        else
13            table.insert(filtered, line)
14        end
15    end
16
17    if #filtered > 0 then
18        -- table.insert(filtered, "")