python_indent_lines.vim

function! SetupIndentConceal()
    " Only for Python files
    if &ft != 'python' | return | endif

    " Clear previous syntax without erroring in case the group doesn't exist
    silent! syntax clear LeadingSpaceConceal

    " Required conceal settings
    set conceallevel=2
    set concealcursor=nvic

    " Match 4 leading spaces, replace last 2 with '| '
    syntax match LeadingSpaceConceal /\(^\s\{2}\)\@<=  / conceal cchar=｜
    " Match 8 spaces
    syntax match LeadingSpaceConceal /\(^\s\{6}\)\@<=  / conceal cchar=｜
    " Match 12 spaces
    syntax match LeadingSpaceConceal /\(^\s\{10}\)\@<=  / conceal cchar=｜
    " Match 16 spaces
    syntax match LeadingSpaceConceal /\(^\s\{14}\)\@<=  / conceal cchar=｜
    " Match 20 spaces (add more rules if needed)
    syntax match LeadingSpaceConceal /\(^\s\{18}\)\@<=  / conceal cchar=｜

    redraw!
endfunction

" Auto-trigger when opening a file or entering a buffer
" autocmd BufEnter,FileType python call SetupIndentConceal()
augroup PythonIndentConceal
    autocmd!
    autocmd FileType python call SetupIndentConceal()
    autocmd BufWinEnter *.py call SetupIndentConceal()
augroup END