To enable it add this to your vimrc:
let g:tmuxcomplete#asyncomplete_source_options = {}

Use own params instead, including ctx

And other options by preferring the injected opts over default values.

Check exit code of command, reset copletion on error
Split async callback functions
Show incomplete candidates as they come in
Add commented out debug logs
Cache mapped candidates
Show incomplete results sligthly different than complete ones

Returns lines with leading non word characters removed. Possible to
complete both lines and words in one run.

Add undocumented -n flag to disable result sorting to be better
streamable.

'splitmode', 'filter_prefix', 'show_incomplete', 'sort_candidates'

See code comment below for details.

with default options