A foreign output (no positive PromptManager node) is decided by the shared
ladder with the MONITOR policy. Certain files are stored at settle with
RUN_MARKS through survive_switch; files only recorded history can decide
wait in their own bounded set and are re-checked once after the run's
outputs are sealed, with the sealed reference. The setting
GalleryConfig.SAVE_FOREIGN_RUNS is read for every file.