ECP vs LangChain

LangChain is a framework for building LLM applications (chains, agents, RAG). ECP (Execution Control Protocol) is a protocol and CLI an orchestrating agent operates.

Positioning

	LangChain	ECP
Primary user	App developer	Orchestrating agent (and the human who ships plugins)
Unit of work	Chain / graph in application code	Portable `*.ecp.ts` workflow + requirements
Governance	Callbacks, tracing products	Policies, `ECP_*` errors, journals
Extensibility	Integrations in the framework	npm plugins that generate CLI commands

Use LangChain when you are writing the application. Use ECP when another agent should delegate a governed graph, validate it, and rerun from a named step. They can coexist: a LangChain app can shell out to ecp run, and an ECP plugin can wrap a model provider.

Next steps