Control plane (L3)

Draft — expand from the L2/L3 boundary map and the orchestration-substrate canon.

The control plane is the run · observe · intervene · learn layer. Its intelligence lives in control nodes on the seams between producer nodes:

• the debug → Hermes ladder — escalating diagnosis of a failing node
• the stuck-node governor — detects and unblocks a node that never wrote
• the background supervisor — watches the run as a whole

A control node always sits on a seam, and can wire itself in three ways: a deterministic hook, a callable tool, or a full producer node.