Function encode 

pub fn encode<T: Document>(doc: &T, collection_id: u32) -> Result<Vec<u8>>

Encode doc into the on-disk record format.

Layout: DocumentHeader (16 bytes) followed by postcard::to_allocvec(doc). Returns the assembled bytes in a fresh Vec<u8>; allocation is unavoidable here because the payload length is not known until postcard runs.

Errors

• Error::Codec if postcard encoding fails.
• Error::DocumentTooLarge if the resulting record exceeds MAX_INLINE_DOC — overflow chains for oversize records are deferred to a later format-minor (see docs/format.md § Document records).