Why: U7 account audit and identity gates advanced on main while U3 account initialization and recovery were in progress.
Evidence: SELF merge-tree checks passed with go test ./... and isolated PostgreSQL store/server tests; exact-head replay follows.
Impact: Preserve pending-account grants, proof-linked recovery, protected CLI delivery, account serialization, and atomic audit.
Refs: IAM U3 r1; U7 PR #185
Why: Concurrent password changes, recovery key reissue, and session admission could accept retired credentials or omit rejected audits.
Evidence: Local Go vet and full tests passed; real PostgreSQL store suite, deterministic interleavings, and two-process contention passed with SELF receipts.
Impact: Account writes and session admission serialize per owner; stale sessions fail closed; checked rejections carry an audit row.
Refs: Agent-System-Dev #486; Agent-System-Backend #185; merge queue Issue #518
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