Use Tailcat through the Node SDK on the actual Cloud host #878

Parent

#868

What to build

A native Node SDK caller opens the same ordered connections as the CLI and executes Machine RPC on the actual Cloud runtime, including cancellation and streaming. This proves the chosen native architecture before Cloud enrollment depends on it.

Acceptance criteria

• Accept shared ordered connection descriptors and use the existing Connector; put Machine RPC Register on the connected session. Keep authorization and capability handling in the backend, never in browser payloads.
• Exercise read-only RPC and a streamed RPC against a real daemon through the SDK; cancellation and deadlines reap helper processes and isolate independent requests. No helper manager interface, pool or second transport implementation.
• Package a verified executable beside the existing native SDK with no runtime build. Record actual Cloud host/runtime, cold/warm invocation, child execution, deadlines and cleanup; local Node alone is insufficient.
• Select a confirmed connection before dispatching a mutation. A lost mutation response must not trigger a new attempt on another entry.
• Rung 1/2 — shared SDK connection/session behavior including cancellation and no mutation replay. Deployment/runtime evidence records the exact artifact and environment. If the real host rejects child execution, record the concrete blocker; do not silently substitute WASM or FFI.

Blocked by

• Manage a Machine from the CLI over Tailcat #876