feat(insights): wire Coach drawer into /insights via hero strip

Closes the loop between the hero strip's "Ask the coach" /
suggested-prompt chips and the Coach drawer:

- `<HeroStrip>` gains an `onAskCoach` prop. When supplied, the
  "Ask the coach" button drops its disabled state + Coming-soon
  tooltip and clicking calls the handler. Older parents that
  haven't adopted the drawer still get the disabled affordance —
  no breaking change.
- `<SuggestedPrompts>`'s `onPick` already routed up via
  `onPickPrompt`; the page wires it to a setter that pre-fills the
  drawer's input AND opens it in the same tick.
- `/insights` owns `coachOpen` + `coachPrefill` state. The drawer
  mounts with `key={prefill ?? "blank"}` so the lazy `useState`
  initialiser fires fresh on every chip transition, sidestepping
  the `react-hooks/set-state-in-effect` rule.

Tests:
- Updates the hero-strip ratchet to allow either disabled (no
  handler) or enabled (handler supplied) states.
- Adds three guards under `insights-polish.test.ts` that pin the
  page-side wiring (CoachDrawer import, hero handler hook-up,
  state ownership).

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

src/app/__tests__/insights-polish.test.ts

@@ -64,6 +64,30 @@ describe("v1.4.19 A3 — dashboard polish", () => {
   });
 });
 
+describe("v1.4.20 B2b — /insights wires the Coach drawer", () => {
+  it("imports <CoachDrawer> and mounts it at the bottom of the page", () => {
+    const src = load(INSIGHTS_PATH);
+    expect(src).toContain(
+      'from "@/components/insights/coach-panel/coach-drawer"',
+    );
+    expect(src).toMatch(/<CoachDrawer\b[\s\S]*?\/>/);
+  });
+
+  it("hero strip's onAskCoach handler opens the drawer with no prefill", () => {
+    const src = load(INSIGHTS_PATH);
+    // The hero supplies onAskCoach which sets coachPrefill to null and
+    // flips coachOpen.
+    expect(src).toMatch(/<HeroStrip[\s\S]*?onAskCoach=\{/);
+    expect(src).toMatch(/<HeroStrip[\s\S]*?onPickPrompt=\{/);
+  });
+
+  it("page owns coachOpen + coachPrefill state", () => {
+    const src = load(INSIGHTS_PATH);
+    expect(src).toContain("setCoachOpen");
+    expect(src).toContain("setCoachPrefill");
+  });
+});
+
 describe("v1.4.19 A3 — /insights polish", () => {
   it("does NOT mount the legacy advisor-card regenerate handler", () => {
     const src = load(INSIGHTS_PATH);

src/app/insights/page.tsx

@@ -43,6 +43,7 @@ import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { InsightAdvisorCard } from "@/components/insights/insight-advisor-card";
 import { HeroStrip } from "@/components/insights/hero-strip";
 import { DailyBriefing } from "@/components/insights/daily-briefing";
+import { CoachDrawer } from "@/components/insights/coach-panel/coach-drawer";
 import { useInsightsAdvisorQuery } from "@/components/insights/use-insights-advisor";
 import { CompareToggle } from "@/components/comparison/compare-toggle";
 // Recharts is ~108 KiB Brotli — defer-load it via a self-contained scatter
@@ -489,6 +490,13 @@ export default function InsightsPage() {
   const { isAuthenticated, user } = useAuth();
   const { t, locale } = useTranslations();
 
+  // v1.4.20 phase B2b — Coach drawer state. The hero strip's
+  // "Ask the coach" button + suggested-prompt chips toggle the drawer
+  // here; the drawer ingests `coachPrefill` once on open and resets on
+  // close so the next open starts blank.
+  const [coachOpen, setCoachOpen] = useState<boolean>(false);
+  const [coachPrefill, setCoachPrefill] = useState<string | null>(null);
+
   const STRENGTH_LABELS: Record<string, string> = {
     stark: t("insights.strengthStrong"),
     moderat: t("insights.strengthModerate"),
@@ -861,6 +869,14 @@ export default function InsightsPage() {
         userName={heroGreetingName}
         onRegenerate={advisor.regenerate}
         regenerating={advisor.isRegenerating}
+        onAskCoach={() => {
+          setCoachPrefill(null);
+          setCoachOpen(true);
+        }}
+        onPickPrompt={(prompt) => {
+          setCoachPrefill(prompt);
+          setCoachOpen(true);
+        }}
       />
 
       <DailyBriefing
@@ -1490,6 +1506,17 @@ export default function InsightsPage() {
           loading={isBmiStatusLoading}
         />
       </section>
+
+      {/* v1.4.20 phase B2b — AI Coach drawer. The drawer reads its
+          initial input value from `prefill`; we change the React `key`
+          on every prefill transition so the lazy `useState` initialiser
+          fires fresh and the composer surfaces the latest chip. */}
+      <CoachDrawer
+        key={coachPrefill ?? "blank"}
+        open={coachOpen}
+        onOpenChange={setCoachOpen}
+        prefill={coachPrefill}
+      />
     </div>
   );
 }