Why bridges are used instead of native paymail inside BRC10…

Why bridges are used instead of native paymail inside BRC100
- Keying model mismatch: Paymail lives in the legacy/xpub/BIP270 world, while BRC100 stacks often use context-derived keys (e.g., BRC-42/43 “BKDS”). Mapping is possible, but one-to-one address/watch patterns don’t carry over natively.
- Metadata and flow expectations: BRC100 flows expect context-rich requests, signatures, and sometimes P2P/0-conf overlays. Plain paymail payments don’t embed those semantics, so the wallet needs translation logic (the sweeper/bridge) to maintain consistency.