RFC: External runtime scope and correlation contract for Bobravoz-style ingress runtimes

[lanycrost]

Summary

The current BubuStack roadmap already points toward Agentic Ingress, CloudEvents, and external runtimes, but the Bobravoz-side runtime contract is still implicit. We need a cross-repo decision on whether Bobravoz-style runtimes are just sample apps or first-class ingress surfaces, and on what correlation/event metadata they must share with the rest of the platform.

Why this needs a discussion

This cuts across bobrapet, bobravoz-grpc, bubu-sdk-go, core, and tractatus. It is bigger than a repo-local issue because the answer changes how external runtimes emit events, attach session metadata, and participate in transport/trace correlation.

Current evidence

• The existing external integration RFC is #49, but it stays fairly high-level around ingress architecture.
• The local Bobravoz runtime currently looks like a hard-coded LiveKit starter pipeline rather than a defined BubuStack ingress/runtime contract.
• bobravoz-grpc already documents transport-side trace propagation and hub/runtime coordination, but there is no clear app-side metadata contract for external runtimes to attach to that surface.
• bobrapet#43 is pushing event semantics toward CloudEvents, which is the obvious candidate boundary for external runtimes too.

Questions to settle

1. Is Bobravoz a sample app, a reference implementation, or a supported ingress runtime surface?
2. What identifiers must an external runtime emit for correlation: session ID, Story/Step references, trigger identity, transport binding name, trace context, something else?
3. Should external runtimes speak CloudEvents directly, or do we want a BubuStack-specific envelope above/beside CloudEvents?
4. Which parts of the contract belong in tractatus, which in core, and which stay runtime-specific?
5. How do we keep this compatible with the broader Agentic Ingress work in #49 without overfitting to a single runtime?

Desired outcome

A scoped contract and ownership map for Bobravoz-style external runtimes so follow-up issues in the SDK, transport, and operator repos can be opened against a shared target instead of inferred behavior.