Problem: the deferred filetype retry in ensure_cache created an infinite
invalidation loop. did_filetype() stays 1 for the lifetime of a buffer
opened via FileType autocmd — it never resets in vim.schedule callbacks.
Each retry reparsed, found has_nil_ft=true again, and scheduled another
retry. Each iteration cleared all extmarks via pending_clear, causing the
deferred syntax pass to bail on its tick check. Result: language syntax
highlighting never settled on buffers containing files with
function-handled extensions (.sh, .bash, .conf, etc).
Solution: add ft_retry_pending guard table. Set before scheduling the
retry, check before scheduling again. The flag is set while the callback
is pending and during the synchronous redraw inside it, preventing the
reparse from scheduling another iteration. Cleared after the callback
completes. Cleaned up on BufWipeout.
Barrett Ruth
0a10f3882d
