Defect-adaptive surface-code methods construct valid logical patches on imperfect hardware, but fault-tolerant computation also requires certifying that requested logical operations remain executable on the resulting irregular geometries. We address this problem for lattice-surgery merges whose interfaces intersect deformed boundaries, unavailable checks, or gauge-inferred operators. Our compiler constructs an admissible seam-measurement set whose elements associate effective seam supports with raw-outcome selectors and schedule metadata. A GF(2) row-space test then determines whether the requested joint parity is realizable modulo pre-merge stabilizer constraints, returning either an explicit parity-extraction rule or a dual witness of non-realizability within the evaluated set. Paired ablations isolate the contribution of the proposed measurement-set construction rules. We further apply the test to configurations generated by Snakes and Ladders (SnL) on 15,000 clustered boundary-defect maps. Adding the proposed boundary-reconstruction rows increases the certification rate from 61.88% to 62.79%, with the gain concentrated in strongly clustered regimes. The framework therefore provides a compiler step that separates defect-adaptive patch construction from the certification and extraction of lattice-surgery parity measurements.