The guard's merge of the first prepass_images frames read nothing the post-refinement
writes and the post-refinement reads nothing the guard writes, but the two ran one after
the other at the start of the tail. The guard now merges the first frames of the outcomes
in place (RotationScaleMerge::SetFrameLimit) with the per-frame scale not written back,
instead of moving the reflections into a copy whose write-back was thrown away, and it
runs on its own thread from just before the post-refinement; its log lines are held and
replayed where the guard's result is read.
Same observations in the same order, same settings: p.mtz is byte-identical (myob, thau,
cytc, kdp, cytc -N 4 / -N 8, --prepass-fraction 1 on four sets, 8a1a). On 8a1a the 3.7 s
guard is now inside the post-refinement, which itself goes from 4.5 to 6.0 s under the
shared load: about 2 s off the tail.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SVmAWnzCmRKAXVUCdc4iNi
leonarski_fandClaude Opus 5.5
de9b2a7cd6