feat(composer): discovery-phase plugin from "I want an app that..." to tracker-loaded stories

Plugin pairs with Symphony — Composer's output (issues in the project's
tracker) is Symphony's input. State-aware /composer command walks the
user through 11 phases: concept, users (with workflow probing for hidden
actors), requirements/NFR/IA, design system, interaction design, flows,
mocks, architecture, stories, roadmap, load. Each phase produces a
reviewable artifact in docs/planning/ (or, for design and interaction,
a project-local skill — see below).

Architecture is intentionally LAST, after the spec is complete. Mocks
are JSX/TSX regardless of final stack and pass a "text feasibility"
audit — every visible string is categorized (static/computed/authored),
computed strings are traced to source data, and any string implying an
unspecified feature halts the commit.

Design system and interaction design are produced as PROJECT-LOCAL
SKILLS in .claude/skills/<slug>-design-system/ and
.claude/skills/<slug>-interaction-design/, not as docs in
docs/planning/. Skills auto-load via description matching whenever UI
work happens; a reference doc gets read once and drifts out of context.
The mocks skill imports tokens directly from the design-system skill
for a single source of truth across mocks and (eventually) real code.

ui-system is currently a PLACEHOLDER — captures the minimum needed for
mocks to proceed with <TBD: ...> markers as a return-pass worklist.
Full interview specification is the next pass.

Council touchpoints baked in: PM/skeptic/end-user after requirements,
end-user/a11y after mocks, full architecture council after architecture,
plus auto-additions (legal-triage on regulated data, privacy-advocate
on PII, finance-controller on money flows).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

composer/skills/ui-system/SKILL.md

@@ -0,0 +1,137 @@
+---
+name: ui-system
+description: Interview the user and produce two project-local skills — a design-system skill and an interaction-design skill — that auto-load whenever UI work is in progress. Output goes to .claude/skills/<slug>-design-system/ and .claude/skills/<slug>-interaction-design/, NOT docs/planning/. The skills load themselves into context when anyone codes UI (mock or real); a plain reference doc would not. Currently a placeholder skill that captures the minimum needed for downstream phases to proceed; planned for a fuller specification pass. Use when the composer skill reaches phase 4 or 5, or when the user asks to "set up the design system" or "specify interaction patterns."
+---
+
+# UI system (placeholder)
+
+> **Status: PLACEHOLDER.** This skill currently captures the minimum
+> design-system and interaction-design content needed for the mocks
+> phase to proceed. A fuller specification pass is planned. When the
+> user returns to flesh this out, expand the interview sections below
+> and the SKILL.md / sidecar templates.
+
+## Why this is a skill, not a doc
+
+A reference document at `docs/planning/design-system.md` gets read once
+and then drifts out of context as the conversation grows. UI work that
+happens later — generating a mock, writing a component, picking a color —
+won't have it loaded.
+
+A **skill** with a description that triggers on UI work is loaded
+automatically every time the trigger matches. That's the whole point of
+the skill mechanism. The design system and interaction design must be
+skills.
+
+## What this skill produces
+
+Two project-local skills, plus their sidecar data files:
+
+```
+.claude/skills/<slug>-design-system/
+├── SKILL.md        ← the skill itself; auto-loads on UI work
+├── tokens.ts       ← machine-readable color / type / spacing / motion tokens
+└── components.md   ← component vocabulary with anatomy
+
+.claude/skills/<slug>-interaction-design/
+└── SKILL.md        ← interaction patterns, state surfaces, input modes, i18n
+```
+
+And two stub pointer files in `docs/planning/` so the planning index
+finds them:
+
+```
+docs/planning/design-system.md         ← pointer; tells humans where the skill lives
+docs/planning/interaction-design.md    ← pointer
+```
+
+## Slug
+
+The skills need a project slug for their `name:` frontmatter, so they
+don't collide with skills from other projects on the same machine.
+
+Resolution order:
+1. If `package.json` has a `name`, slugify it.
+2. Else if a git remote exists, slugify the repo name.
+3. Else ask the user. Default to the directory name.
+
+Slug rule: lowercase, hyphenated, kebab-case, ASCII only. Example:
+`SourdoughTracker` → `sourdough-tracker` → skill `sourdough-tracker-design-system`.
+
+## design-system interview (placeholder pass)
+
+Ask the user, in order, with sensible defaults:
+
+1. **Existing material?** Brand assets, mood boards, screenshots,
+   "make it look like Linear/Notion/Stripe", or nothing. If material
+   exists, ingest it before asking the rest.
+2. **Color**: brand color(s), neutral scale (warm/cool/true), dark mode
+   (yes/no/system). Offer to generate accessible contrast pairs.
+3. **Typography**: one family or two (display + body), size scale base
+   and ratio, line-height policy.
+4. **Spacing**: scale base (4px / 8px), key spacing tokens.
+5. **Radii**: tight / medium / pillowy.
+6. **Shadows**: flat / subtle / generous.
+7. **Visual motion**: default duration, default easing.
+8. **Components**: confirm vocabulary against `ia.md`.
+
+Mark unanswered with `<TBD: ...>` so the return pass has a worklist.
+
+### Write phase — design-system
+
+1. Write `.claude/skills/<slug>-design-system/SKILL.md` from
+   `templates/design-system/SKILL.md`. Substitute the slug into the
+   `name:` field and the project name into the `description:`.
+2. Write `.claude/skills/<slug>-design-system/tokens.ts` from
+   `templates/design-system/tokens.ts`. Fill in the values gathered in
+   the interview; `<TBD>` for unanswered.
+3. Write `.claude/skills/<slug>-design-system/components.md` from
+   `templates/design-system/components.md`.
+4. Write `docs/planning/design-system.md` from the pointer template —
+   one paragraph saying where the skill lives.
+
+## interaction-design interview (placeholder pass)
+
+Ask, in order:
+
+1. **Primary input**: touch / mouse / keyboard / mixed. Primary, supported, not supported.
+2. **State surfaces**: pick one pattern per action class.
+3. **Motion**: minimal / restrained / expressive. `prefers-reduced-motion` always honored.
+4. **Breakpoints**: count, primary design target.
+5. **i18n**: locales planned, RTL, string-length budget.
+6. **Empty/loading/error/offline**: one declared posture each.
+7. **Time formatting**: relative threshold, absolute format.
+8. **Keyboard**: global shortcuts, escape behavior.
+
+### Write phase — interaction-design
+
+1. Write `.claude/skills/<slug>-interaction-design/SKILL.md` from
+   `templates/interaction-design/SKILL.md`.
+2. Write `docs/planning/interaction-design.md` pointer.
+
+## Re-entry
+
+When the user returns to flesh this out fully:
+- Expand the interviews above.
+- Expand the SKILL.md and sidecar templates.
+- Both skills are version-controlled in `.claude/skills/` — re-running
+  this phase shows the user a diff before overwriting.
+
+The downstream contract is: `composer-mocks` reads the **skills**, not
+the planning pointer files. That contract does not change as the
+templates grow.
+
+## Hard rules even in placeholder mode
+
+- **Always produce both skills with sidecars.** Mocks can't proceed without them.
+- **Always slug-namespace** so projects on the same machine don't collide.
+- **Mark unknowns with `<TBD: ...>`** rather than inventing — TBDs are the return-pass worklist.
+- **Don't pretend.** If the user has nothing and no opinions, say so in the SKILL.md: "No design direction set; defaults applied. Revisit before mocks are committed."
+- **Tell the user what just happened.** After write, print:
+  ```
+  Wrote two project skills:
+    .claude/skills/<slug>-design-system/SKILL.md
+    .claude/skills/<slug>-interaction-design/SKILL.md
+  These auto-load whenever UI work is happening. Verify after restart
+  with /agents (they should appear as project-local skills).
+  ```