Create and manage repo-local work artifacts for a user “task request” by generating `.artifacts/artifacts/{request_id}/` with `plan.md`, `todo.md`, and `walkthrough.md`, then indexing completed work into ChromaDB stored at `.artifacts/chroma_db/` for 7-day recall. Use when the user wants (1) a tracked/confirm-before-execute workflow, (2) a minimal final answer that links to a walkthrough, or (3) to ask “what did we do before with the artifacts skill?” and you should answer by querying the ChromaDB artifacts index.