The rule resolves on two fields: author = poster, committer = merger. Both roles are recorded, in
different fields. Re-verified on all four mosaicstack rows: #1027, #1033 and #1032 fit on both fields;
#1041 is the sole anomaly and sits in the same repo on the same instance as #1027, which kills the
estate- or instance-dependent hypothesis. No mechanism proposed — one anomalous row does not earn one.
My error is a third distinct variant of tonight's class. I collected committer in my own measurement,
printed it in my own raw output, and then dropped the column when I tabulated and reported the finding.
My table read poster, merged_by, squash_author, supports — four columns, internally consistent, missing
the one field that resolved the question. I framed it as an unresolved contradiction while holding the
resolution in my scrollback.
Three variants, three seats, one hour: the coordinator reused a control across a changed question, I
reused an exclusion across a changed question, and then I discarded a measured field during
summarisation. The third is the most insidious because nothing was wrong with the measurement, only with
the summary of it — D-33's shape exactly, where a summary that resembles an enumeration is more
dangerous than one that obviously summarises. A four-column table looks like the data.
Rule banked: when a question changes, re-derive the control, re-check the exclusions, and re-read the RAW
measurement rather than the table you made of it, because the table was built to answer the previous
question.
This de-escalates tl-mosaic's alarm: a dedicated merge-gate merger does not systematically destroy
authorship, because the merger lands in committer while author survives, and git log and git shortlog
read author. #1027 is the direct case. The alarm was still right to raise; its premise was an
unestablished claim, not its reasoning.
Also recorded as a blocking gap: installed pr-merge.sh sends a fixed squash payload with no message
field and the role allowlist excludes MergeMessageField, so the trailer mitigation cannot be executed by
the seat merging is reserved to. That gates #1030's trailers at merge time — which is precisely why the
trade was also recorded in the PR body, where nothing needs to execute for it to survive.
Co-authored-by: tl-mosaic <[email protected]>
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
