cordis.yml-wired demo proving the full stack end to end: mock-echo
LlmAdapter (streams text; calls the echo tool on "echo <text>"),
echo tool, stdio chat UI plugin (consumes only the agent/* taxonomy),
and a JSONL persistence plugin demonstrating the write-behind +
session/flush checkpoint pattern. Runs unbuilt via tsx with loader,
include, and HMR live-reload all active (yarn demo).
