{"id":"rotation-preserves-fd-invariant","text":"After `_maybe_rotate` returns, `self._fd` is guaranteed non-None and open for writing (assuming it was non-None on entry), because `_rotate()` always opens a new file.","truth_value":"IN","source":"entries/2026/05/29/write-ahead-log-wal-_maybe_rotate.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"rotation-preserves-fd-invariant","truth_value":"IN","reason":"premise"}]}}