A hosted SQLite that caps value size (a Durable Object's 2 MB) cannot hold a large file's stored blob in one blob.content value. With the new db.DriverConfig.MaxValueBytes set, a stored value over the limit is written in 1,000,000-byte parts to blobpart(rid, seq, content), created on first use, leaving blob.content NULL and blob.size the expanded length, so phantoms (size < 0) stay unambiguous. Chunking sits below compression: hashes, deltas and the wire format are unchanged.

internal/blob owns the seam (ReadStored, WriteStored, InsertStored, StoredHead, DropStored, SweepParts and two scan expressions), and every direct reader or writer of blob.content now goes through it: delta rewrite and undelta, receive, clone send and walk, compaction, sparse demotion, seed drop, shun purge, horizon cost and cone preparation.

Zero, the default, keeps every value inline and creates no table, so local stores stay byte-identical. A store with blobpart rows is not readable by stock fossil; enable it only for hosted backends.

Closes #459 check-in: 1fd12b3ed3 user: [email protected] tags: feat/chunked-blobs, main, trunk