\begin{thebibliography}{99} \bibitem{HistoricalClaude} E. F. W. Heffern, \emph{Geometric Descent on the Markov Surface}, working draft v32, archived October 2026, pp.~38--40, historical computational reports. The earlier search was assisted by Claude. \bibitem{HistoricalAnnouncement} E. F. W. Heffern, public LinkedIn announcement of a 24-minute Markov-number search, 23 October 2026, 14:54:57.771 UTC, activity 7519411048115003392. Platform metadata and the source URL are retained in the verification supplement's evidence packet; see \href{https://www.linkedin.com/posts/elleard-felix-webster-heffern-joseph-by-confirmation-2953a3104_markovnumbers-activity-7519411048115003392-4NaJ}{the public announcement}. \bibitem{Verification} E. F. W. Heffern, \emph{Markov 50 Billion Verification Package}, version 1, completed and sealed 28 October 2026; public derivative version 1.1 in \emph{Computational supplements for Meridians on the Markov Surface}, Zenodo, 2 November 2026. \href{https://doi.org/10.5281/zenodo.23874075}{doi:10.5281/zenodo.23874075}. \bibitem{TrillionVerification} E. F. W. Heffern, \emph{Certified magnitude-band verification of the first one trillion Markov values}, completed 9 November 2026 (CST). Final independent and portable replay reports, retained receipt chains, resource records and \texttt{v16\_Trillion\_Verifier\_Recovery.zip}, included with this release. \href{https://doi.org/10.5281/zenodo.24096109}{doi:10.5281/zenodo.24096109}. \bibitem{SelectedValues} E. F. W. Heffern, \emph{Six selected Markov values: full decimal expansions and certified numerical ranks}. Digits first posted 9 November 2026, \href{https://doi.org/10.5281/zenodo.24093257}{doi:10.5281/zenodo.24093257}; rank certification and unchanged digit files accompany the present release. \bibitem{BandVerification} E. F. W. Heffern, \emph{Certified magnitude-band, residue-first verification of the first 500 billion Markov maxima}, completed 9 November 2026. Final evidence: \texttt{v1\_Band\_500\_Billion\_Final\_Evidence.json}; frozen recovery archive: \texttt{v20\_Band\_500\_Billion\_Recovery.zip}. The comparison includes 550,693,634,649 configurations. The final evidence and reconciliation accompany this manuscript's source; the recovery archive is identified by SHA-256 in Section~\ref{sec:verification-evidence}. \bibitem{FiftySupplement} E. F. W. Heffern, \emph{Computational chronology and proofs for the fifty-billion verification}, supplement to the present manuscript, version 4, 7 November 2026. \bibitem{Baragar1996} A.~Baragar, \emph{On the unicity conjecture for Markoff numbers}, Canadian Mathematical Bulletin \textbf{39} (1996), no.~1, 3--9. \href{https://doi.org/10.4153/CMB-1996-001-x}{doi:10.4153/CMB-1996-001-x}. The computational benchmark $M<10^{140}$ is reported in Section~4, p.~9. \bibitem{Aigner} M. Aigner, \emph{Markov's Theorem and 100 Years of the Uniqueness Conjecture: A Mathematical Journey from Irrational Numbers to Perfect Matchings}, Springer, Cham, 2013. \href{https://doi.org/10.1007/978-3-319-00888-2}{doi:10.1007/978-3-319-00888-2}. \bibitem{CS} \.{I}. \c{C}anak\c{c}{\i} and R. Schiffler, \emph{Snake graphs and continued fractions}, European J. Combin. \textbf{86} (2020), 103081. \href{https://doi.org/10.1016/j.ejc.2020.103081}{doi:10.1016/j.ejc.2020.103081}. \bibitem{DegreeVerification} E. F. W. Heffern, \emph{Meridian Degree 10,000 Reproducibility Package}, computational supplement, 31 October 2026; address-convention revision, 7 November 2026. Original computational release in \emph{Computational supplements for Meridians on the Markov Surface}, version 1.0, Zenodo, 2 November 2026. \href{https://doi.org/10.5281/zenodo.23874075}{doi:10.5281/zenodo.23874075}. \bibitem{CorridorRecord} E. F. W. Heffern, \emph{Markov Meridian Residue Supplement}, version 1.18, and \emph{Corridor-to-Corridor Induction}, version 1.3, unpublished supplementary research records, 7 November 2026. The corridor results used here are proved in Section~\ref{sec:corridors}. \bibitem{LPTV} C. Lagisquet, E. Pelantov\'a, S. Tavenas and L. Vuillon, \emph{On the Markov numbers: fixed numerator, denominator, and sum conjectures}, Adv. Appl. Math. \textbf{130} (2021), 102227. \href{https://doi.org/10.1016/j.aam.2021.102227}{doi:10.1016/j.aam.2021.102227}. Preprint: \href{https://arxiv.org/abs/2010.10335}{arXiv:2010.10335}. \bibitem{LLRS} K. Lee, L. Li, M. Rabideau and R. Schiffler, \emph{On the ordering of the Markov numbers}, Adv. Appl. Math. \textbf{143} (2023), 102453. \href{https://doi.org/10.1016/j.aam.2022.102453}{doi:10.1016/j.aam.2022.102453}. \bibitem{McShane} G. McShane, \emph{Convexity and Aigner's conjectures}, preprint (2021), \href{https://arxiv.org/abs/2101.03316}{arXiv:2101.03316}. \bibitem{RS} M. Rabideau and R. Schiffler, \emph{Continued fractions and orderings on the Markov numbers}, Adv. Math. \textbf{370} (2020), 107231. \href{https://doi.org/10.1016/j.aim.2020.107231}{doi:10.1016/j.aim.2020.107231}. \bibitem{Musiker2002} G.~Musiker, \emph{A conjectured combinatorial interpretation for Markov numbers}, REACH memorandum, 27 June 2002. \href{https://faculty.uml.edu/jpropp/reach/musiker/NewResults.ps}{Original memorandum}; \href{https://faculty.uml.edu/jpropp/reach/index.html}{REACH archive}. \bibitem{IMPV2003} A.~Itsara, G.~Musiker, J.~Propp, and R.~Viana, \emph{Combinatorial interpretations for the Markov numbers}, REACH manuscript, 10 January 2003, Theorem~3.1. \href{https://faculty.uml.edu/jpropp/reach/Itsara/markovversion1.pdf}{Original manuscript}. \bibitem{Propp} J.~Propp, \emph{The combinatorics of frieze patterns and Markoff numbers}, \href{https://arxiv.org/abs/math/0511633}{arXiv:math/0511633}, first posted 25 November 2005; published in \emph{Integers} \textbf{20} (2020), A12. \bibitem{TanZhang2026} H.~Tan and Y.~Zhang, \emph{A computational verification of the Markov uniqueness conjecture for $z\le10^{500000}$}, \href{https://arxiv.org/abs/2611.01007v1}{arXiv:2611.01007v1} (31 October 2026), Sections~2.3--2.4 and~3.2. Computational evidence archived 26 October 2026: \href{https://doi.org/10.5281/zenodo.23670834}{doi:10.5281/zenodo.23670834}. \end{thebibliography}