UE5 writes Saved/running.dat as a "session in progress" marker. If
the previous session exited uncleanly (SIGKILL, crash), it lingers,
and SN2 pops up an invisible 0×0 Error dialog at next launch that
the GameThread blocks on forever — visible only as a black screen
with a spinning loader. Wrap the Steam command to clear the marker
files before each launch.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
