Module reader 

WAL reader for crash recovery and replay.

Reads records sequentially from a WAL file, validating checksums and magic numbers. Stops at the first corruption point — everything before that point is the committed prefix.

Replay invariants

• Replay is deterministic: the same WAL file always produces the same sequence of records.
• Replay is idempotent: replaying the same record twice has the same effect as replaying it once.
• Unknown optional record types (bit 15 clear) are skipped.
• Unknown required record types (bit 15 set) cause a replay failure.

Structs

WalReader

Sequential WAL reader.

WalRecordIter

Iterator over WAL records.