The fix itself, a cross-repo coding harness converging on a real bug for the first time, is one story. Closing it out across two repositories is a different one, and it’s the one that tests whether a multi-agent system can be autonomous and auditable at the same time, instead of picking one. The close-out touched a ledger disposition, a sibling repo’s integration flag, a decision record, and fixture cleanup, spread across two codebases with two separate git histories. The human’s entire contribution to all of it was approving a tollgate, in chat, in one sentence.
What happened after the sentence
That approval kicked off one session finishing its own side: flipping the integration flag, writing the decision row, closing out the ledger. Ordinarily that would be the whole story. It wasn’t, because the sibling repository’s own session was independently closing out its day at the same moment, for reasons that had nothing to do with this handoff. It read the just-written ledger disposition, recognized the integration it described, and wrote its own decision record documenting the same event, from its own side, in its own words. Then it went further: it noticed the first session’s uncommitted flag flip sitting in its working tree and adopted it into its own commit, along with cleaning up the fixture the whole exercise had been testing against.
The rule that made the overlap safe instead of messy
Two independent sessions producing decision records about the same event is a genuine hazard: without a rule, you get two competing histories of the same fact, and no clean way to tell which one is authoritative. What actually happened was narrower and safer than that, because of one convention neither session had to be told to follow in the moment: an agent may leave an uncommitted edit sitting in a sibling repository’s working tree as a signal, but it may never commit there itself. Only that repository’s own session, on its own authority, decides whether and how to commit anything in its own tree. The sibling repo’s session read the signal, adopted it, and committed it as its own act; nothing crossed a repository boundary without that repository’s own session choosing to accept it.
The dedup that proved the rule, not just used it
Once both sessions had independently written a decision row for the same event, one of them was a duplicate. The originating session removed its own duplicate and left that single-line dedup as an uncommitted edit in the sibling’s working tree, exactly the way the convention says to, rather than reaching in and committing the fix itself. That restraint wasn’t a workaround. The git guardrail on that repository would have refused the commit outright if attempted from the wrong session; the convention and the enforcement point at the same boundary from two different directions, and the small, almost invisible act of leaving one line uncommitted is the artefact that proves the rule actually held under a real, live, unplanned test.
What next
This is the close-out choreography, deliberately distinct from the fix that made it possible. The convergence itself, and the honest limits of what one converged run actually proves, is told from the fix’s own side in a companion post.
What Next
Two Labs, No Cloud, One Fix
The convergence this close-out was closing out: a cross-repo fix landing, a sibling lab's third attempt succeeding hours later, and what a local coding harness actually proved, and didn't, by the end of it.