deck-skills

Use when editing existing slides in deck.md — rewriting body text, swapping layout, toggling freeze/skip/ignore, fixing citations, reordering. The slide's `key` is preserved through every edit. Anything that creates new content (a new deck from a template, or a new slide that needs a fresh key) goes through `deck-new`.

Use when creating anything new for deck.md — either a brand-new deck from a Google Slides template (0→1) or a new slide added to an existing deck (n→n+1, with a freshly minted 4-hex `key`). Trigger when the user provides a Google Slides URL and asks to make a deck, or says "add a slide after X", "insert a quote slide here", "new section header before Appendix". Edits to existing slides (body rewrite, layout swap, freeze/skip toggle) go through `deck-edit`.