Layer 2 describes facts about the local device and current links. It is intentionally not a recommendation or authority system.
The Rust diagnostics model exposes DeviceProfile, DeviceCapabilities, and LinkBenchmarkResult (presented as link benchmarks). These cover device profile information, discovered runtime/capability facts, GPU acceleration facts, local and peer benchmark observations, and timestamps/measurement mode. Capability probes support quick and full modes; full probing does not reuse an insufficient quick capability result.
Current diagnostics also carry current-session liveness and endpoint availability through the Bridge peer model, and Settings can report provider availability through a safe natural-v1 provider health check. Developer Tools presents these diagnostics and can request refreshes or benchmark work. The source-of-truth types and probes are in src-tauri/src/diagnostics.rs, device_profile.rs, capability_probe.rs, commands.rs, and src/lib/types.ts.
Observations are local or current-session scoped unless a different feature explicitly defines persistence. A reported endpoint is not a durable route; a reported provider configuration is not execution approval; and a benchmark is not a transfer guarantee.
Layer 2 describes facts. It does not produce planner commands, peer rankings, recommended devices, trust, consent, or authority. In particular, device facts do not command Layer 3 scheduler policy and paired-device display metadata does not establish Layer 4 routeability.
See Layer 3 for the scheduler that makes policy decisions and Layer 4 for current-session liveness and routeability semantics.