We introduced GAINs and HCINs as the architecture of multi-agent AI. The obvious question now is: how do you actually build one? The striking answer is that the agent tools developers already use — Claude Code, OpenAI Codex, OpenClaw, and Hermes — have each, independently, implemented the GAIN/HCIN primitives. Their defaults even encode the same lessons the architecture points to. GAINs and HCIN are the map; these tools are the implementation surface.
The mapping
Stripped to primitives, the correspondence is close to one-to-one:
- Coordinator (CCA / PAC) → Claude Code's team lead; Codex's orchestrator (or an Agents-SDK