How the chain touches Divi

Link	Direction	Trust
MCHK checkpoint	Divi → side-chain (read)	none; it is a public block hash
DGCH anchor	side-chain → Divi (write)	evidence only
tDIVI bridge	funds both ways	custodial: you trust the operator
HTLC swap	funds both ways	trustless

This course is about the last two. Both work with Divi testnet funds only.

The bridge and htlc modules are specified in ARCHITECTURE.md (sections 4.3 and 6.2) and implemented in crates/dg-system/src/bridge.rs and crates/dg-market/src/htlc.rs.