tl-mosaic found #1041 on mosaicstack/stack where poster == branch author == coder-mos2 and the squash
took NEITHER — it took the merger. Mos re-tested its own 22 and found 0 of 24 rows had poster !=
merged_by, so none could distinguish the hypotheses. Its own framing is the sharpest statement of the
class: a sample can be decisive for one question and empty for the next one asked of it.
I made the mirror error. I excluded #1033 and #1032 as non-discriminating and said so explicitly,
believing it made my evidence more careful. That exclusion was correct for "is the branch author
discarded?" — poster equalled branch author, so no loss was visible — and wrong for "poster or merger?",
where they discriminate cleanly because merged_by differs from the poster in both. I threw away my own
discriminating rows by carrying a classification forward across questions. Mos reused a control across
questions; I reused an exclusion.
Re-measured, and this is the first data separating poster from merger: #1027 poster mos-dt-0 / merger
Mos / author mos-dt-0 supports POSTER; #1033 and #1032 poster coder-mos1 / merger mos-dt-0 / author
coder-mos1 both support POSTER; #1041 poster coder-mos2 / merger mos-dt-0 / author mos-dt-0 supports
MERGER. Three to one, genuinely contradictory, one instance and one repo. Reported as contradictory data
rather than a majority verdict — 3-to-1 is a hypothesis to test, not a conclusion to adopt, and a third
factor such as merge path or a settings change is not excluded.
What survives is the half that matters and it is untouched: the branch commit author is discarded, at 29
discriminating rows across three repos and two estates. Every mitigation rests on that half.
Which is why Co-authored-by trailers are the only sound mitigation rather than belt-and-braces: they are
robust to all three hypotheses, and the withdrawn poster-equals-author rule would have failed #1041
outright, where the poster WAS the author and attribution was lost anyway.
Co-authored-by: tl-mosaic <[email protected]>
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
