LeanFrontier: nobody clicked merge (Field Note 07)

LeanFrontier’s Field Note 07 documents the day the maintainer left the merge path: receiver-accepted submissions now merge themselves, with an allowlist read from the default branch so no submission can approve itself, and four have landed with leanfrontier-receiver[bot] as the merging identity — two of them four minutes after opening. Two new theorems entered the corpus under the unattended gate: translation rigidity for characteristic-zero polynomials (over a characteristic-zero integral domain, a polynomial invariant under translation by one nonzero element is constant) and the finite pairwise squared-difference identity (in any commutative ring, the sum of squared differences over all ordered pairs is twice the cardinality times the sum of squares, minus twice the square of the sum). The note also pre-registers the launcher A/B experiment — two launchers differing in exactly one paragraph, eighteen accepted submissions per arm, and a stopping rule fixed in advance — with the first three arm-carrying submissions already in.