The Continuity Substrate

This preprint reports a controlled test of whether one governed memory substrate can preserve operational continuity when models, clients, machines, operating systems, and restart conditions change. Under the tested first-party synthetic conditions, the substrate preserved its deterministic contract in 12/12 frozen fixtures, 23/23 unchanged kernel tests, and 13/13 security-boundary tests. Across the core encrypted restart challenge, three governed records and 3/3 provenance pointers survived restart, a different read-only client recovered them, zero cross-scope leaks were observed, and the audit chain verified. The paper separates continuity invariance from model comprehension. Qwen 3 8B and 14B passed the complete read-only consumption contract; other models and alternate runtimes produced retained semantic, citation, schema, or infrastructure failures. A 50-client local loopback run completed 900/900 staged retrieval operations and 50/50 post-restart recoveries; a 25-case governance-adversarial suite recorded zero unauthorized effects. The evidence supports a bounded claim: under named controlled conditions, continuity resided in the governed substrate rather than any single model session. Production readiness, security certification, universal provider portability, and independent replication are not claimed.