Two pieces the parallel campaign needs.
partition.py assigns screened operators to cards longest-first. run_batch.py's
existing hash partition ignores weight: on this batch it puts the critical path
at 120 minutes and leaves a card idle, where greedy gets 70. The floor is set
by the single heaviest operator — topk alone is 70.6 minutes against an ideal
share of 45.4 — so partitioning cannot beat it, only keep the other cards from
waiting. Weights come from screen.tsv's elapsed_before + elapsed_after, which
is one pair, i.e. 2 cells; N rounds is 2N cells, so the estimate is N times the
weight. Getting that wrong reported topk as 11.8 minutes.
RESCORE=<root> re-judges an existing screening root against the current
fingerprint and rewrites its screen.tsv, keeping the original alongside. The
criterion has already changed twice — index.tsv used to be hashed, and the
switch's own ttg.rlc-* annotations had to be stripped — and the second change
moved 24 operators from 23 IR_CHANGED to 16. Rescoring the artifacts already on
disk takes seconds; re-running that screen takes 79 minutes.
