Sanctum SecOps LLC This document defines a non-critical X.509 certificate extension, the Post-Quantum Hybrid Commitment (PQCHC), that allows a certificate issued with a classical or hybrid key to carry a verifiable, cryptographically bound commitment to a specific future post-quantum algorithm and a Commitment Validity Time. The PQCHC commitment binds to a hash of the committed future public key and algorithm identifier, enabling a relying party to verify that a subsequently issued post-quantum certificate honors the earlier commitment. This mechanism provides a crypto-agility signal for certificate-lifecycle automation, including ACME Renewal Information (ARI), to plan and verify PQC migration.