## Why

Phase 3A defines gateway-only manifests and control datagrams but has no versioned
contracts for the separately deployed gateway's registration, admission authority,
capability intersection, lifecycle, or encoded relay framing. Phase 3C-G needs those
contracts frozen before Data Plane or Connection Server consumers change.

## What Changes

- Add bounded JSON bindings for gateway registration, heartbeat/drain, tunnel admission,
  session-scoped authority, capability selection, channel framing, provider state, and
  stable errors.
- Extend the tunnel protobuf descriptor with the same versioned control messages.
- Register only gateway-owned media/input flow identifiers; keep provider endpoints and
  credentials out of client-facing manifests.

## Ownership and provenance

Protocol owns the wire contract. The contract is original VerseVDI work derived from the
Phase 3A schemas and public Apollo/Moonlight behavior recorded in the Planning Hub. No
GPL source is copied into this repository.

## Non-goals

- Provider implementation, database policy, QUIC implementation, media decoding, or client
  rendering.
- Direct client-to-Apollo routing, provider endpoint exposure, or a speculative plugin ABI.

## Stop conditions

Unknown versions, malformed bounds, no capability overlap, downgrade without explicit
acknowledgement, forbidden provider fields, and oversized frames fail closed.