PQ-MedTrust: Coupling Continuous Trust to Post-Quantum Credential Revocation for Autonomous Clinical Agents

Autonomous clinical agents increasingly act on Internet-of-Medical-Things (IoMT) endpoints, yet existing access-management mechanisms are human-centric, quantum-vulnerable, and poorly suited to continuous action-level enforcement. We present PQ-MedTrust, which couples an identity–behavior–context trust score with risk-dependent decay to post-quantum revocation of agent credentials based on Decentralized Identifiers and Verifiable Credentials, and we characterize where behavioral trust succeeds, becomes detection-latency limited, or fails. In a liboqs testbed on a general-purpose CPU, classical, hybrid, and PQC-only handshakes stay below 1.5 ms, but a hybrid authorized action (handshake, credential, delegation token, and request) occupies 21.1 KB against 1.8 KB classically. The trust-to-revocation path, which signs and pushes a revocation record, takes 0.07 ms with classical and 11.1 ms with SLH-DSA signatures. Over 1000 simulated runs per scenario, policy enforcement revokes every out-of-scope and one-shot mimicry attack (scope is a generator label, not a dose-range check), whereas adaptive stealth is detected in 20.2% of runs at 24 h and 75.3% at 120 h; without the generator’s risk labels, 24 h detection falls to 5.6%. The pooled benign false-positive rate is 1.8% under a reliable context but rises sharply when context degrades or benign agents emit the event class that marks adaptive stealth. A graduated response revokes none of 500 unannounced-emergency runs, although 92.4% reach clinician confirmation, and still revokes every policy violation.