ADR-017 locks the client/adapter architecture:
- CallClient opens QUIC connections, shares dispatch loop with CallAdapter
- Connection direction independent of call direction (both sides can call)
- from_call adapter: discovers remote ops via services/list + services/schema,
registers with forwarding handlers (same pattern as from_openapi/from_mcp)
- to_openapi/to_mcp: project local ops to external protocols
- OperationAdapter trait: produces (OperationSpec, Handler) pairs
- Cross-node call tree: abort cascade propagates through from_call handlers
- Credentials from capabilities (ADR-014), adapter ops Internal by default (ADR-015)
The dispatch POC at /workspace/@alkdev/dispatch demonstrated head/worker over
SSH+axum; under the call protocol it's cross-node composition via from_call.
Connection topology (who advertises, who opens) is independent of call
direction — runner pattern, dispatch pattern, and P2P all work.