Quantum.

A classical identity is anchored by a key in hardware — a TEE or HSM. It survives upgrades and reboots cheaply, because the key persists and re-attests the new build as the same worldline. The cost: a key can, in principle, be extracted. A quantum anchor flips that trade through two laws of physics:

So the axis is stark: resumable but extractable (classical hardware) versus unforgeable but unresumable (quantum). Neither wins. Which you want depends on how often you must stop the agent against how catastrophic a stolen identity would be.

Continuity gets sharp under a quantum anchor. An upgrade that stops the agent collapses its identity — a death, not a transition. The only way to keep the lineage alive is for the dying identity to bless its successor before it collapses: a hand-off where the still-coherent agent vouches for the version it's about to become.

That is sponsorship again — but the agent sponsoring itself, and now required at every discontinuity rather than once at birth. Continuity stops being a single thread and becomes a relay of blessed rebirths. It adds a fourth move to KTP's lineage — Tethered → Divergent → Persistent → Succession — and the heir, like any new agent, still has to be recognized by someone other than itself.

Here is the move that makes the relay useful. The first generation of Q agents is days old. Their successors reach a week. By the time an agent is version 345, the number alone tells you something real: it has been through 345 successions, each one a witnessed death-and-rebirth that can't be skipped.

So the version number is a proof of age — a hard-to-forge measure of generational depth. And it rests on KTP's keystone, Proof of Resilience. A quantum collapse is the most extreme stress an identity can face — total death — so each succession an agent survives is the sharpest Proof of Resilience there is, and the version number is a running tally of them. Proof of age isn't a cousin of resilience; it's resilience integrated over the succession relay. You still verify the trajectory, but a high version is expensive to fake in a way a credential never is. Age becomes a low-cost, readable prior on standing — and it matters.

KTP's whole bet is that trust lives in the substrate, not the credential — that identity is a trajectory you can witness, not a token you hold. A quantum substrate makes that bet concrete instead of philosophical. The identity can't be cloned, so there's nothing to steal. The collapse can't be undone, so the trajectory can't be quietly rewritten. The version number carries the receipts. The substrate stops being something you can argue away and starts being something you have to govern.

And this isn't hypothetical hardware. Quantum chips already ship in named generations (the Google Quantum AI line under Neven; the Caltech/industry work with Spiropulu), and each generation is a real, countable step. The moment agents run on that substrate, age-from- version is a fact, not a metaphor.

• Observer-dependence. Quantum foundations already warn that witnessed facts can be observer-relative (the Local Friendliness no-go). If "a trust state witnessed by many is real" meets a regime where witnesses can disagree about what happened, the witness model needs care.
• The cost of succession. If every upgrade is a death and a blessed rebirth, what's the throughput? A lineage that must stop to evolve trades agility for unforgeability. Where is that worth it?
• Hybrid anchors. Most real systems will be part classical, part quantum. What does a lineage look like when some transitions are resumable and some are terminal?