Parallel short trajectories in regular polygons: a type convention and signed angle law

This credited research note verifies the signed type law associated with Fuchs Conjecture 2.6 using an explicit segment-parity convention. It proves first-vertex existence and the rule for every n >= 3 and every actually admissible transformed angle, with the required even shift for even n. The unrestricted imported statement combining the rule with a bare type-zero endpoint-angle criterion is false on direct diagonals for every n >= 5; this is distinguished from the source's preceding generic open sectors. The convention is a supported completion, not an authenticated author erratum or uniquely compelled raw-disjunction reading. Alper Ferudun's version 1.0 preprint of 9 October 2026, DOI 10.5281/zenodo.23267641, Definition 1.1, Remark 1.2 and Theorem B, already contains the same nontrivial theorem, parity/diagonal qualification and first-vertex existence. His uniform angular and endpoint-reflection argument, explicit double-surface shears and finite descent substantially overlap the mechanisms here. Veech's exact double-polygon surfaces and shears, Boissy-Lanneau's affine centrality, and earlier pentagon finite-length descent are credited. Neither the theorem, type correction, trivial triangle case, full-affine formulation nor descent is advertised as new. The fixed original PR191 candidate already contains the common-germ route. GitHub reports PR creation on 1 October 2026, and the current related Zenodo record reports creation on 9 October 2026. These dates and presently retrievable fixed bytes do not establish historical public exact-byte visibility, relative discovery, firstness, awareness or independence. These are contemporaneous overlapping treatments, with no certification of simultaneous independent discovery, current openness or historical priority. Selective primary reading and incomplete publisher/version-history comparisons are documented. The deposit includes the concise research note, standalone LaTeX source and a portable standard-library verification package: original protected snapshots, independent source-first mathematical and priority audits, exact first-hit tracers, machine-readable source pins, ordinary/optimized checks and deliberately false guard controls. Finite computations corroborate the analytic proof and do not establish universality or priority. AI tools were used extensively for reconstruction, derivation, search, drafting, computation and adversarial verification. This preprint is unrefereed and has not undergone conventional human peer review.