ADR-0017: Mesh bridging & retro-hardware

Status

Accepted (Phase 10)

Context

Some peers cannot speak QUIC (MCUs, serial links, legacy LANs).

Decision

• Introduce a BridgeFrame length-prefixed envelope compatible with the CNK framing story.
• Working adapter: plain TCP (TcpBridgeEndpoint) with in-process exchange tests.
• Stubs: --features bridge-serial and bridge-bluetooth expose adapters that return explicit roadmap errors (no hardware in CI).

Honesty

Bluetooth/serial are not implemented. Planet-scale bridging is not claimed. Microcontroller peers can reuse CNK no_std frames once a serial adapter is filled in.

Consequences

Document TCP as the supported legacy path; keep stubs feature-gated.