Transport Architecture

MLForm transport has four layers:

1. Core contract:
   • submit(request)
   • stream(request)?
   • openSession(request)?
2. Capability model:
   • modes
   • safety
   • limits
   • auth
   • delivery
3. Middleware:
   • auth
   • retry
   • timeout
   • circuit breaker
   • rate limit
   • dedup
   • cache
   • tracing
   • metrics
4. Orchestration:
   • routing
   • weighted routing
   • fanout
   • quorum fanout
   • fallback
   • pipeline
   • racing
   • hedged
   • load balancing

The engine is protocol-agnostic. HTTP, GraphQL, SSE, WebSocket, gRPC, local inference, workers, or custom RPC all fit as long as the transport implements the contract.

Policy logic is scoped through TransportPolicyContext. Shared cache, rate limit, breaker, and health backends should key decisions by scope, not by ad hoc local strings.