# MAVLink and telemetry

Kaptan emits telemetry using MAVLink 2 framing. The production receiver does
not promote inbound MAVLink frames to authority records:

- MAVLink 1 is discarded.
- CRC-invalid MAVLink 2 frames are discarded.
- Signed frames are discarded because no signature verifier or persistent
  replay state exists.
- Unsigned MAVLink 2 frames are also discarded; a V2 CRC detects corruption,
  not authentication.

`TODO(signing)`: any future inbound authority requires verified MAVLink 2
signing, configured source/target binding, persistent anti-replay state, and a
provisioning/key-rotation policy as one reviewed feature.

Telemetry transmission uses bounded frame classes. A critical frame may
replace pending best-effort traffic, but never the DMA-owned active buffer.
Completion retries preserve ordering and retain a transiently busy frame for a
later service turn.