{"id":"wal-has-no-before-images","text":"WALRecord stores only `key` and `value` (the new value) with no `old_value` field, making undo structurally impossible from the log alone","truth_value":"IN","source":"entries/2026/05/29/topic-undo-logging-and-steal-policy.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"wal-has-no-before-images","truth_value":"IN","reason":"premise"}]}}