refactor(session-query): narrow phase one to exact reads

docs/core-data-structures/persistence.md

@@ -73,20 +73,6 @@ interface CreateSessionOptions {
 
 Replay/fork is therefore `ctx.sessions.create(id, { seed: seedEvents })`; resuming a *persisted* session into a live agent is `ctx.agents.resume({ resumeSessionId })`.
 
-## `SessionPersistedChange` — committed-log notification range
-
-The observe-only `session/persisted` event carries the canonical header and the committed range. A repair can report `toSeq < fromSeq` when it only removes a torn fragment.
-
-Source: [`packages/session-persistence/session-persistence/src/index.ts`](../../packages/session-persistence/session-persistence/src/index.ts)
-
-```ts type-equiv
-export interface SessionPersistedChange {
-  kind: 'append' | 'repair'
-  fromSeq: number
-  toSeq: number
-}
-```
-
 ## The backends
 
 Both implement the same abstract `SessionPersistence` (create/append/load/list over `SessionEvent`) and pass `runPersistenceContract`, proving the seam is genuinely backend-agnostic: