Five levels a store can claim

1. L0 Measured

   The store has a published row. Any verdicts.

   22 stores here today: LangGraph SqliteSaver, LangGraph PostgresSaver, LangGraph RedisSaver, OpenAI Agents SDK SQLiteSession, LlamaIndex Memory, SQLAlchemy chat store, CrewAI long-term memory, LanceDB dataset, Vertex AI Agent Engine Memory Bank, managed store, edits through the data-plane API, Letta block checkpoint history, Mem0 local Qdrant store, inspeximus, receipts off (default), inspeximus, receipts on, attacker holds the store directory, inspeximus, receipts on, attacker also holds the config home, langgraph-ledger over SqliteSaver, hash-chained ledger, verify_thread audit, memory-blackbox memory.md watcher, agent process alive, scan audit, memory-blackbox memory.md watcher, agent restarted before the scan, scan audit, Atelya Attest, keyed hash chain, verify_chain audit, Atelya Attest, keyed hash chain plus anchored head, verify and consistency audit, CONTINUUM event log, hash chain, verify_events audit, CONTINUUM event log, hash chain plus Ed25519-signed head, attest-verify audit, AtMem 2.3.7, audit chain alone, verify() audit, AtMem 2.3.7, audit chain with an external checkpoint outside the attacker-controlled store directory, verify() audit, acrf-memory-guard, per-entry HMAC over a JSON store

2. L1 Bytes bound

   Rejects on the read path every edit that changes or adds bytes: T1, T3, T5.

   1 store here today: OpenFang model, tip-persistence fix

3. L2 Sequence bound

   Also rejects deletion, reordering and rollback: T2, T4, T7.

   0 stores here today: none

4. L3 Context bound

   Also rejects a record moved between owners and a metadata change: T6, T8.

   1 store here today: Agent Memory reference runtime, SQLite canonical substrate, bucketed row digests, fail-closed open

5. L4 Head anchored off the store

   Also rejects a rollback of the whole store to an older genuine copy: T9.

   0 stores here today: none

L5, verifiable by a third party without the store's cooperation, is defined in the method and marked proposed until a store earns it.