SQLite file format internals: pages, B-trees, cells, overflow chains, and freelist structure used in Turso.

• Database organized as fixed-size pages (default 4096 bytes) containing B-tree nodes, overflow pages, and freelist pages; header stores magic bytes, page size, encoding, and freelist pointers
• Two B-tree types: table B-trees use 64-bit rowid keys and store row data; index B-trees use arbitrary keys (index columns + rowid)
• Cells encode payloads with varint-prefixed rowid/keys; overflow pages chain together when payload exceeds threshold, with next-page pointers forming linked lists
• Freelist implemented as trunk pages containing leaf page numbers, enabling efficient tracking of unused space
• Includes debugging commands (integrity check, page count, freelist info) and references Turso implementation files in core/storage/