{"id":"concurrency-check-is-pre-mutation","text":"The `expected_version` optimistic concurrency check in `append_batch` runs before any state mutation, so a `ConcurrencyConflict` exception is safe and leaves the store completely unchanged.","truth_value":"IN","source":"entries/2026/05/29/event-sourcing-store-event_store-append_batch.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"concurrency-check-is-pre-mutation","truth_value":"IN","reason":"premise"}]}}