Provider SDK and external protocol

Provider SDK and external protocol

In-process Rust adapters implement inferqos_provider_sdk::ProviderAdapter and run validate_estimate plus the repository conformance suite. Adapters estimate, stream dispatch, report health, map throttles/retry-after, and reconcile actual work without exposing vendor types to the scheduler.

External adapters implement protocol/provider/v1/provider.proto over a local Unix socket by default. Localhost TCP is acceptable; remote use requires mutually authenticated TLS. Version 1 is experimental during InferQoS 0.x. Minor additive fields remain wire-compatible; breaking RPC or semantic changes require a new protobuf package. Plugins are privileged code: pin artifacts, restrict filesystem/network access, and treat compromise as equivalent to provider credential loss.

The runnable reference service is cargo run -p inferqos-provider-protocol --bin example-adapter. See the external protocol reference for transport controls and an end-to-end configuration.