DSH Preset Authoring

1. A preset is one directory: agent.cordis.yml (required composition) plus optional preset.yml (display metadata: name, description, numeric order; order sorts the roster).
2. Name the directory (the preset id) [a-z0-9][a-z0-9-]* kebab-case — discovery skips any other id outright, and authoring APIs reject it.
3. agent.cordis.yml is a top-level YAML list of rows {id, name, config?}; every name is an @deepseek-ai/* package (with optional config) or cordis:group whose config is a recursive row list.
4. Take each row and its config fields verbatim from an official shipped preset or an install you validated — never invent field names; unverified rows fail the package-existence gate or break the boot.
5. Install under the harness-home user root ~/.dsh/.agent-presets/<id>/ (files are the only composition editor; copy() is the API alternative and never overwrites).
6. Validate against a real install: node tools/validate-presets.mjs --harness <dsh node_modules root> from awesome-dsh-presets — YAML (incl. !!js dialect) parses, rows carry id+name, cordis:group recurses, every referenced @deepseek-ai/* package exists.
7. Expect live discovery: list()/resolve() re-read roots per call, and each session tracks its composition file's mtime/size stamp — a new session picks up your edit, an already-joined session keeps the generation it started on.
8. A directory that is broken (missing/unreadable agent.cordis.yml) is listed with its reason, occupying the id: fix the file or delete the directory; do not shadow it with a duplicate.
9. Switching presets applies only to a blank session (nothing produced yet); a produced session answers agent-preset-locked — do not claim a switch happened.
10. Deliver the preset directory, the validation output against the harness version you used, and one blank-session verification that it boots with the intended tools.