Before acting, read `llmanspec/config.yaml` and follow its `context` and `rules` if present.

Common commands:
- `llman sdd context --task "<description>" --paths "<files>"` (find relevant specs). Uses the pageindex agentic tree backend (needs `LLMAN_SDD_INDEX_CHAT_MODEL`). Preset via `LLMAN_SDD_INDEX_BACKEND`.
- `llman sdd list` (list changes)
- `llman sdd list --specs` (list specs with purpose/scope metadata)
- `llman sdd show <id>` (show change/spec)
- `llman sdd validate <id>` (validate a change or spec)
- `llman sdd validate --all` (bulk validate)
- `llman sdd index rebuild` (rebuild the pageindex tree index — no model needed)
- `llman sdd index check` (check index freshness)
- `llman sdd archive run <id>` (archive a change)
- `llman sdd archive freeze [--before YYYY-MM-DD] [--keep-recent N] [--dry-run]` (freeze archived dirs)
- `llman sdd archive thaw [--change <id> ...] [--dest <path>]` (restore from cold-backup)
- `llman sdd graph [CHANGE] [--format mermaid] [--scope active|archived|all] [--depth N]` (generate change dependency graph)
