design-system

When this skill is invoked: ## 1. Parse Arguments & Validate Resolve the review mode (once, store for all gate spawns this run): 1. If `--review [full|lean|solo]` was passed → use that 2. Else read `production/review-mode.txt` → use that value 3. Else → default to `lean` See `docs/framework/director-gates.md` for the full check pattern. A system name or retrofit path is **required**. If missing: 1. Check if `design/gdd/systems-index.md` exists. 2. If it exists: read it, find the highest-priority system with status "Not Started" or equivalent, and use `question`: - Prompt: "The next system in your design order is **[system-name]** ([priority] | [layer]). Start designing it?" - Options: `[A] Yes — design [system-name]` / `[B] Pick a different system` / `[C] Stop here` - If [A]: proceed with that system name. If [B]: ask which system to design (plain text). If [C]: exit. 3. If no systems index exists, fail with: > "Usage: `/design-system <system-name>` — e.g., `/design-system movement` > Or to fill gaps in an existing GDD: `/design-system retrofit design/gdd/[system-name].md` > No systems index found. Run `/map-systems` first to map your systems and get the design order." **Detect retrofit mode:** If the argument starts with `retrofit` or the argument is a file path to an existing `.md` file in `design/gdd/`, enter **retrofit mode**: 1. Read the existing GDD file. 2. Identify which of the 8 required sections are present (scan for section headings). Re...