Add design council skill and interaction-and-feedback contract

.claude/skills/council/SKILL.md

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+---
+name: council
+description: Consult the design council — the external interaction, content, and accessibility canon (IBM Carbon, GOV.UK Design System, WAI-ARIA APG, Nielsen Norman) — before committing a user-facing design decision. Auto-invoke when writing user-facing error / empty-state / notification copy, or when designing the keyboard / focus / ARIA behavior of an interactive widget (modal, menu, listbox, toast, splitter, disclosure). Also invokable on demand for any interaction, content, accessibility, or usability decision.
+disable-model-invocation: false
+---
+
+# Design Council
+
+A standing panel of external design authorities, consulted the way we already consult
+Carbon: **local corpora, grepped — not WebFetched.** The council **advises**; Astrolabe's
+own contract **decides**. When a source conflicts with `SOUL.md`,
+`docs/architecture/09-visual-design.md` (visual contract), or
+`docs/architecture/10-interaction-and-feedback.md` (interaction contract), **our contract
+wins** — note the divergence and move on.
+
+## Two modes
+
+- **Pointwise (now).** Consult on a single decision in front of you, via the routing table
+  below. Cheap, precise, fits the editing flow — this is the default, and what the
+  auto-triggers fire.
+- **Audit (future).** Periodically sweep the **whole codebase** against the roster — every
+  interactive widget vs. APG, every user-facing string vs. GOV.UK/Carbon content rules,
+  every data surface vs. the loading/empty/error triad, every latency path vs. NN/g budgets
+  — and emit a prioritized gap list into `docs/architecture/10` + `// TODO`s. This is a
+  fan-out review (closer in shape to `/alignment`, but graded against external canon), best
+  run at **milestone boundaries**, not per change — and much of it is milestone-gated anyway
+  (you can't audit modals or datasets that don't exist yet).
+
+## How to convene (the routing rule)
+
+Pull the **minimal** relevant member(s) for the decision at hand — do **not** sweep all
+four; that wastes tokens and dilutes the answer. Map the decision to its seat(s):
+
+| Decision in front of you                                   | Primary seat → then                                    |
+| ---------------------------------------------------------- | ------------------------------------------------------ |
+| Error / failure / empty-state / notification **copy**      | **GOV.UK** → Carbon notifications → NN/g heuristic #9  |
+| Keyboard / focus / ARIA roles of an **interactive widget** | **WAI-ARIA APG** → Carbon component                    |
+| **Latency / feedback / loading / progress** budgets        | **NN/g** response-time limits → Carbon loading pattern |
+| **Forms / validation / destructive-action** flow           | **GOV.UK** → Carbon                                    |
+| General **usability** gut-check on a flow                  | **NN/g** 10 heuristics                                 |
+| **Visual** styling (type, spacing, colour, component look) | **Carbon** + our `docs/architecture/09`                |
+
+Then: read the cited file(s), extract the **specific** principle, and report it back with
+a **citation (member + file path)** and a one-line "how it lands in Astrolabe." Don't
+paraphrase the whole source — quote the rule that decides the question.
+
+## The roster
+
+All paths are under `/Users/oleh/code/reference/`. Treat clones as **inspiration, not
+law** — they drift; the published guidance is the truth, the clone is the fast index.
+
+| Member                         | Path                               | Authoritative for                                                                            | How to query                                                                                                                                                                           |
+| ------------------------------ | ---------------------------------- | -------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| **IBM Carbon**                 | `carbon-website/src/pages/`        | Notification taxonomy, status levels, empty/loading states, content basics, data-viz styling | grep `.mdx` under `components/notification`, `patterns/{empty-states,loading,status-indicator}-pattern`, `guidelines/content`                                                          |
+| **GOV.UK Design System**       | `govuk-design-system/src/`         | Error & validation messages, failure pages, forms, plain-language content, accessibility     | `index.md` under `components/{error-message,error-summary,notification-banner}`, `patterns/{problem-with-the-service-pages,service-unavailable-pages,check-answers}`, `accessibility/` |
+| **WAI-ARIA APG**               | `aria-practices/content/patterns/` | Keyboard interaction, focus management, ARIA roles/states for widgets                        | `<pattern>/<pattern>-pattern.html` — e.g. `dialog-modal`, `alertdialog`, `alert`, `listbox`, `menu-button`, `disclosure`, `switch`, `tabs`, `tooltip`, `windowsplitter`                |
+| **Nielsen Norman (distilled)** | `principles/nielsen-norman.md`     | 10 usability heuristics; response-time / feedback budgets (0.1s / 1s / 10s)                  | read directly — it is short and curated                                                                                                                                                |
+
+## Close the loop
+
+The council exists so we **don't re-derive the same decision twice**. When a consultation
+settles a _recurring_ question (not a one-off), capture the resolution into our own
+contract — `docs/architecture/10-interaction-and-feedback.md` for interaction/feedback,
+`09-visual-design.md` for visual — via the `/doc-update` skill. Upstream canon informs;
+the downstream contract records. A code site that embeds such a rule should cite our
+contract, not the external source.
+
+## Adding a seat
+
+1. If it's an open-source repo, shallow-clone it into `/Users/oleh/code/reference/`
+   (`git clone --depth 1 …`). If it's articles/blogs (not cloneable), **distill** the
+   stable parts into `reference/principles/<source>.md` with attribution + links, like
+   the NN/g note.
+2. Add one row to **the roster** and one routing entry above.
+3. Keep it lean — a seat earns its place only if it's authoritative for a decision the
+   others don't cover well.
+
+Candidate future seats (not yet seated): **FT Visual Vocabulary / Datawrapper** (chart
+choice — our domain), **Shopify Polaris** (UX-writing depth), **web.dev** (perceived
+performance / PWA / offline UX).