Decompose a specification file into shells with YAML frontmatter. Each shell captures the wiring invariants (Produces, Consumes, Covers) and high-level Implementation Steps without committing to file paths. Use when the user asks to \"draft shells\", \"create shells\", \"break spec into shells\", \"
Decompose a specification file into shells with YAML frontmatter. Each shell captures the wiring invariants (Produces, Consumes, Covers) and high-level Implementation Steps without committing to file paths. Use when the user asks to \"draft shells\", \"create shells\", \"break spec into shells\", \"decompose spec into sessions\", \"draft shells from spec\", \"generate shells from spec\", or \"make