FTN Packet Format

OxideBBS implements byte-preserving FTN Type-2 packet primitives in the oxidebbs-ftn crate.

Current packet support:

• PacketHeader models the Type-2/Type-2+ header fields used by OxideBBS.
• PacketReader reads packet bytes from impl Read.
• PacketWriter writes packet bytes to impl Write.
• PacketMessage preserves raw message body bytes, including non-UTF-8 legacy text.
• MessageAttribute exposes common packed-message attribute bits.

The reader rejects unsupported packet and packed-message types. Message body bytes remain authoritative for duplicate hashing and re-export; display text is decoded only at higher layers.

Tosser, scanner, bundle, and nodelist workflows build on these primitives and are tracked separately from this packet-format reference.