This playbook assumes two fundamental premises: that Cryptographically Relevant Quantum Computers (CRQCs) are technically feasible and will be built, and that the activation signal has been triggered through public demonstration of a quantum computer. The activation trigger - indisputable demonstration of a ~100 logical qubit quantum computer - provides sufficient warning while maintaining urgency, with about an order-of-magnitude more logical qubits needed to reach the ~1000 logical qubits required for Bitcoin's ECC cryptographic foundation to be within CRQC striking distance.

Disclaimer: the premises outlined here are hypothetical. Neither the authors nor their employer(s) make any assertion that CRQCs will actually be realized, nor that the thresholds described will necessarily be achieved. This playbook is a contingency framework, intended for consideration in the event that such assumptions become reality.

Given this threat landscape, our fundamental goal is to ensure Bitcoin can continue to function as a secure peer-to-peer electronic cash system after CRQCs capable of breaking ECDLP exist. This requires:

• Forward protection through quantum-resistant cryptography for all new addresses,
• Migration capability for users to securely move funds from hash-protected (non-reused) addresses,
• Management for the ~1.7 million BTC in P2PK (and potential other exposed public key script types), and
• Network continuity throughout the transition period.

The following playbook, developed through discussions with Core developers and informed by Bitcoin's history of successful protocol upgrades, provides a roadmap for achieving these objectives while respecting Bitcoin's open, rough consensus process.