Session history and recovery

Long sessions cannot depend on an in-memory message array. Compatible runtimes SHOULD maintain event logs, rollout/history records, snapshots, and read models.

Layers

event_log, rollout_log, session_snapshot, thread_read_model, context_boundary, and evidence_export may share storage, but their semantics must stay distinct.

Compaction

Compaction SHOULD record trigger, affected turns, summary ref, replacement history or continuation ref, token usage before/after, preserved pending actions, incidents, artifact refs, evidence refs, and errors or retries.

Compaction must not silently drop unresolved actions or active incidents.

Rollback and reconstruction

Rollback SHOULD record target, removed turns, surviving context baseline, affected tools/artifacts/subagents/jobs, and read-model repair.

Recovery SHOULD load session shell, thread summaries, recent window, active thread read model, pending actions, queued turns, subagents, and jobs. Partial recovery must be marked degraded.