chore: establish hwlab l0 contract skeleton

protocol/README.md

@@ -0,0 +1,42 @@
+# HWLAB Protocol Contract
+
+The L0 protocol contract defines the common language between cloud services,
+gateway services, simulated boxes, agent workers, CLI tooling, and future
+hardware integrations.
+
+All MVP implementations must preserve these invariants:
+
+- Use JSON-RPC 2.0 envelopes for command-style API calls unless a later
+  service contract explicitly narrows the transport.
+- Emit auditable records for user, system, gateway, worker, and hardware
+  actions that mutate state or produce evidence.
+- Describe box hardware through capabilities, resource state, and wiring
+  constraints instead of service-specific ad hoc fields.
+- Treat DEV as the only MVP acceptance environment.
+- Keep service identities within the frozen service ID list in the root
+  README.
+
+## Frozen Tables
+
+The database contract is intentionally named here before migrations exist so
+parallel MVP work shares stable terminology:
+
+- `projects`
+- `gateway_sessions`
+- `box_resources`
+- `box_capabilities`
+- `wiring_configs`
+- `patch_panel_status`
+- `hardware_operations`
+- `audit_events`
+- `agent_sessions`
+- `worker_sessions`
+- `agent_trace_events`
+- `evidence_records`
+
+## Schema Status
+
+Schemas in `protocol/schemas` are draft-2020-12 JSON Schemas. They define L0
+field names, identities, relationships, timestamps, and state enums. Later
+service work may tighten validation, but must not silently rename these L0
+contract fields.