/usr/include/ags/audio/task/ is in libags-audio-dev 1.4.24-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ags/audio/task/ags_add_audio.h
/usr/include/ags/audio/task/ags_add_audio_signal.h
/usr/include/ags/audio/task/ags_add_effect.h
/usr/include/ags/audio/task/ags_add_note.h
/usr/include/ags/audio/task/ags_add_point_to_selection.h
/usr/include/ags/audio/task/ags_add_recall.h
/usr/include/ags/audio/task/ags_add_recall_container.h
/usr/include/ags/audio/task/ags_add_region_to_selection.h
/usr/include/ags/audio/task/ags_add_soundcard.h
/usr/include/ags/audio/task/ags_append_audio.h
/usr/include/ags/audio/task/ags_append_audio_threaded.h
/usr/include/ags/audio/task/ags_append_channel.h
/usr/include/ags/audio/task/ags_append_recall.h
/usr/include/ags/audio/task/ags_apply_presets.h
/usr/include/ags/audio/task/ags_apply_synth.h
/usr/include/ags/audio/task/ags_cancel_audio.h
/usr/include/ags/audio/task/ags_cancel_channel.h
/usr/include/ags/audio/task/ags_cancel_recall.h
/usr/include/ags/audio/task/ags_change_soundcard.h
/usr/include/ags/audio/task/ags_clear_audio_signal.h
/usr/include/ags/audio/task/ags_clear_buffer.h
/usr/include/ags/audio/task/ags_crop_note.h
/usr/include/ags/audio/task/ags_export_output.h
/usr/include/ags/audio/task/ags_free_selection.h
/usr/include/ags/audio/task/ags_init_audio.h
/usr/include/ags/audio/task/ags_init_channel.h
/usr/include/ags/audio/task/ags_link_channel.h
/usr/include/ags/audio/task/ags_move_note.h
/usr/include/ags/audio/task/ags_notify_soundcard.h
/usr/include/ags/audio/task/ags_open_file.h
/usr/include/ags/audio/task/ags_open_sf2_sample.h
/usr/include/ags/audio/task/ags_open_single_file.h
/usr/include/ags/audio/task/ags_remove_audio.h
/usr/include/ags/audio/task/ags_remove_audio_signal.h
/usr/include/ags/audio/task/ags_remove_note.h
/usr/include/ags/audio/task/ags_remove_point_from_selection.h
/usr/include/ags/audio/task/ags_remove_recall.h
/usr/include/ags/audio/task/ags_remove_recall_container.h
/usr/include/ags/audio/task/ags_remove_region_from_selection.h
/usr/include/ags/audio/task/ags_remove_soundcard.h
/usr/include/ags/audio/task/ags_reset_audio_connection.h
/usr/include/ags/audio/task/ags_resize_audio.h
/usr/include/ags/audio/task/ags_save_file.h
/usr/include/ags/audio/task/ags_seek_soundcard.h
/usr/include/ags/audio/task/ags_set_audio_channels.h
/usr/include/ags/audio/task/ags_set_buffer_size.h
/usr/include/ags/audio/task/ags_set_format.h
/usr/include/ags/audio/task/ags_set_input_device.h
/usr/include/ags/audio/task/ags_set_output_device.h
/usr/include/ags/audio/task/ags_set_samplerate.h
/usr/include/ags/audio/task/ags_start_sequencer.h
/usr/include/ags/audio/task/ags_start_soundcard.h
/usr/include/ags/audio/task/ags_switch_buffer_flag.h
/usr/include/ags/audio/task/ags_tic_device.h
/usr/include/ags/audio/task/ags_toggle_pattern_bit.h
/usr/include/ags/audio/task/ags_unref_audio_signal.h
/usr/include/ags/audio/task/recall/
/usr/include/ags/audio/task/recall/ags_apply_bpm.h
/usr/include/ags/audio/task/recall/ags_apply_sequencer_length.h
/usr/include/ags/audio/task/recall/ags_apply_tact.h
/usr/include/ags/audio/task/recall/ags_reset_peak.h
/usr/include/ags/audio/task/recall/ags_set_muted.h