Seven-chapter tutorial under docs/cordis-tutorial/ for agent developers
new to Cordis: first plugin, lifecycle/effects, services, events,
config, composition/HMR, and a final chapter registering a tool against
real harness services. Every transcript was produced by running the
chapter files in a gitignored tmp/ scratch directory.
Published to both website locales as mirrored English pages under a new
'Cordis tutorial' develop-sidebar section; a Chinese pair can be added
later without route changes.