feat(insights): surface the diversity hint as a heading lightbulb

The measurement-diversity nudge used to render as an inline note block on
each category page; read in context it looked like a data finding rather
than a tip and confused. Move it onto the heading as a small Lightbulb
glyph that only mounts when the spread is genuinely lopsided; the hint
text it used to show inline now lives in a hover / focus Tooltip with an
accessible name. The sub-page shell carries the glyph in the heading row,
drops the removed explainer trigger, and normalises the foot-of-page
"show all readings" control to the standard secondary-button height.

messages/de.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — alle Werte",
       "valuesPageDescription": "Jeder einzelne Wert hinter dieser Kennzahl. Einträge lassen sich direkt bearbeiten oder entfernen.",
       "diversity": {
+        "trigger": "Messhinweis",
         "weekday": "Die meisten deiner {metric}-Werte fallen auf einen Wochentag. Messungen an anderen Tagen ergeben ein vollständigeres Bild.",
         "timeOfDay": "Die meisten deiner {metric}-Werte fallen auf eine ähnliche Tageszeit. Unterschiedliche Zeiten ergeben ein vollständigeres Bild."
       },

messages/en.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — all readings",
       "valuesPageDescription": "Every reading behind this metric. Edit or remove an entry directly.",
       "diversity": {
+        "trigger": "Measurement tip",
         "weekday": "Most of your {metric} readings land on one weekday. Logging on other days gives a fuller picture.",
         "timeOfDay": "Most of your {metric} readings land at a similar time of day. Varying the time gives a fuller picture."
       },

messages/es.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — todas las mediciones",
       "valuesPageDescription": "Cada medición detrás de esta métrica. Edita o elimina una entrada directamente.",
       "diversity": {
+        "trigger": "Consejo de medición",
         "weekday": "La mayoría de tus mediciones de {metric} caen en un mismo día de la semana. Registrar en otros días ofrece una imagen más completa.",
         "timeOfDay": "La mayoría de tus mediciones de {metric} caen a una hora similar del día. Variar la hora ofrece una imagen más completa."
       },

messages/fr.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — toutes les mesures",
       "valuesPageDescription": "Chaque mesure derrière cette métrique. Modifiez ou supprimez une entrée directement.",
       "diversity": {
+        "trigger": "Conseil de mesure",
         "weekday": "La plupart de vos mesures de {metric} tombent le même jour de la semaine. Enregistrer d'autres jours donne une image plus complète.",
         "timeOfDay": "La plupart de vos mesures de {metric} tombent à une heure similaire de la journée. Varier l'heure donne une image plus complète."
       },

messages/it.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — tutte le misurazioni",
       "valuesPageDescription": "Ogni misurazione dietro questa metrica. Modifica o rimuovi una voce direttamente.",
       "diversity": {
+        "trigger": "Suggerimento di misurazione",
         "weekday": "La maggior parte delle tue misurazioni di {metric} cade in un solo giorno della settimana. Registrare in altri giorni offre un quadro più completo.",
         "timeOfDay": "La maggior parte delle tue misurazioni di {metric} cade in un orario simile della giornata. Variare l'orario offre un quadro più completo."
       },

messages/pl.json

@@ -1969,6 +1969,7 @@
       "valuesPageTitle": "{metric} — wszystkie pomiary",
       "valuesPageDescription": "Każdy pomiar stojący za tą metryką. Edytuj lub usuń wpis bezpośrednio.",
       "diversity": {
+        "trigger": "Wskazówka pomiarowa",
         "weekday": "Większość Twoich pomiarów {metric} przypada na jeden dzień tygodnia. Pomiary w inne dni dają pełniejszy obraz.",
         "timeOfDay": "Większość Twoich pomiarów {metric} przypada o podobnej porze dnia. Różne pory dają pełniejszy obraz."
       },

src/components/insights/__tests__/sub-page-shell.test.tsx

@@ -64,13 +64,42 @@ describe("<SubPageShell>", () => {
     );
   });
 
-  it("keeps the explainer trigger glyph when explainerMetric is set", () => {
+  it("no longer paints the round `?` explainer trigger next to the heading", () => {
     const html = render(
       <SubPageShell title="Blood pressure" explainerMetric="bloodPressure">
         <span />
       </SubPageShell>,
     );
-    // The `?` glyph stays available alongside the inline caption.
-    expect(html).toMatch(/data-slot="metric-explainer-trigger"/);
+    // v1.8.6 — the `?` popover affordance was dropped; only the inline
+    // definition caption remains.
+    expect(html).not.toMatch(/data-slot="metric-explainer-trigger"/);
+  });
+
+  it("renders the diversity nudge node inside the heading row", () => {
+    const html = render(
+      <SubPageShell
+        title="Weight"
+        diversityNudge={<span data-slot="diversity-probe" />}
+      >
+        <span />
+      </SubPageShell>,
+    );
+    // v1.8.6 — the nudge moved up to the heading row (a `Lightbulb`
+    // glyph), no longer an inline block beneath the stat strip.
+    const headerEnd = html.indexOf("</header>");
+    const probeIdx = html.indexOf('data-slot="diversity-probe"');
+    expect(probeIdx).toBeGreaterThan(-1);
+    expect(probeIdx).toBeLessThan(headerEnd);
+  });
+
+  it("mounts no coach launch surface when coachLaunch is omitted", () => {
+    const html = render(
+      <SubPageShell title="Pulse">
+        <span />
+      </SubPageShell>,
+    );
+    // The coach icon only renders under the launch provider + flags; the
+    // shell renders nothing for it on the default path.
+    expect(html).not.toContain('data-slot="coach-launch-icon"');
   });
 });

src/components/insights/measurement-diversity-nudge.tsx

@@ -3,6 +3,12 @@
 import { useQuery } from "@tanstack/react-query";
 import { Lightbulb } from "lucide-react";
 
+import {
+  Tooltip,
+  TooltipContent,
+  TooltipProvider,
+  TooltipTrigger,
+} from "@/components/ui/tooltip";
 import { useAuth } from "@/hooks/use-auth";
 import { useTranslations } from "@/lib/i18n/context";
 import { queryKeys } from "@/lib/query-keys";
@@ -18,6 +24,14 @@ import { detectMeasurementDiversity } from "@/lib/insights/measurement-diversity
  * when the spread is genuinely lopsided — surfaces a gentle hint to
  * measure on other days / times.
  *
+ * v1.8.6 — the hint moved off the page body and onto the heading. The
+ * inline `role="note"` block confused on the category pages (it read
+ * like a data finding rather than a tip), so the nudge now renders as a
+ * small `Lightbulb` glyph beside the page title. The hint text the block
+ * used to show inline lives in a hover / focus Tooltip; the glyph mounts
+ * only when the spread is actually lopsided, so a healthy metric shows
+ * no extra affordance at all.
+ *
  * v1.8.3 anti-freeze posture: the read is a bounded `limit`-capped query
  * with a 5-minute `staleTime`, fires only after the page has mounted
  * (no SSR blocking), and renders nothing while in flight or when the
@@ -75,18 +89,29 @@ export function MeasurementDiversityNudge({
   const message = t(`insights.subPage.diversity.${signal.kind}`, {
     metric: metricLabel,
   });
+  const triggerLabel = t("insights.subPage.diversity.trigger");
 
   return (
-    <div
-      data-slot="measurement-diversity-nudge"
-      role="note"
-      className="bg-muted/40 text-muted-foreground flex items-start gap-2.5 rounded-lg px-3 py-2.5 text-sm"
-    >
-      <Lightbulb
-        className="text-dracula-yellow mt-0.5 size-4 shrink-0"
-        aria-hidden="true"
-      />
-      <p className="leading-relaxed">{message}</p>
-    </div>
+    <TooltipProvider delayDuration={150}>
+      <Tooltip>
+        <TooltipTrigger asChild>
+          <button
+            type="button"
+            data-slot="measurement-diversity-nudge"
+            aria-label={triggerLabel}
+            className="text-dracula-yellow hover:text-dracula-yellow/80 focus-visible:ring-ring/50 -my-3 -mx-2 inline-flex min-h-11 min-w-11 shrink-0 items-center justify-center rounded-full transition-colors focus-visible:ring-2 focus-visible:outline-none"
+          >
+            <Lightbulb className="size-4" aria-hidden="true" />
+          </button>
+        </TooltipTrigger>
+        <TooltipContent
+          data-slot="measurement-diversity-nudge-body"
+          align="start"
+          className="max-w-xs leading-relaxed"
+        >
+          {message}
+        </TooltipContent>
+      </Tooltip>
+    </TooltipProvider>
   );
 }

src/components/insights/sub-page-shell.tsx

@@ -6,7 +6,7 @@ import { ListOrdered } from "lucide-react";
 
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
-import { MetricExplainer } from "@/components/insights/metric-explainer";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { useScrollResetOnRoute } from "@/hooks/use-scroll-reset-on-route";
 import { useTranslations } from "@/lib/i18n/context";
 import { cn } from "@/lib/utils";
@@ -40,18 +40,16 @@ export interface SubPageShellProps {
    */
   description?: string;
   /**
-   * v1.8.0 — when set, a `?` glyph next to the heading opens a static
-   * "What is X?" explainer (popover on desktop, bottom-sheet on phones).
-   * The value is the metric key feeding
-   * `insights.subPage.explainer.<metric>{Title,Body}`. Omitted on the
-   * mother page; every routed metric sub-page passes its key.
+   * v1.8.0 — when set, the metric's static "What is X?" definition
+   * renders as a muted caption directly beneath the heading. The value
+   * is the metric key feeding `insights.subPage.explainer.<metric>Body`.
+   * Omitted on the mother page; every routed metric sub-page passes its
+   * key.
    *
-   * v1.8.4 — the same explainer body also renders inline as a muted
-   * caption directly beneath the heading, so the one- to two-sentence
-   * definition is visible without opening the popover. The `?` glyph
-   * stays as the always-available pointer for the same copy. Both the
-   * inline caption and the popover read the identical
-   * `insights.subPage.explainer.<metric>Body` string — no duplicated copy.
+   * v1.8.6 — the round `?` popover affordance next to the heading is
+   * gone (it read as restless next to the title). The inline definition
+   * caption stays — it is the single always-visible source of the
+   * one- to two-sentence definition, no tap required.
    */
   explainerMetric?: string;
   /**
@@ -77,11 +75,27 @@ export interface SubPageShellProps {
    */
   statStrip?: ReactNode;
   /**
-   * v1.8.5 W4b — measurement-diversity nudge mounted just under the stat
-   * strip. A gentle hint when readings cluster on one weekday / time.
-   * Self-gating: renders nothing when the spread is healthy.
+   * v1.8.5 W4b — measurement-diversity nudge.
+   *
+   * v1.8.6 — relocated from an inline block under the stat strip to a
+   * `Lightbulb` glyph beside the heading (a hover / focus Tooltip carries
+   * the hint copy). The node is `<MeasurementDiversityNudge>`, which is
+   * self-gating: it renders the glyph only when readings cluster on one
+   * weekday / time, and nothing when the spread is healthy.
    */
   diversityNudge?: ReactNode;
+  /**
+   * v1.8.6 — opt-in Coach launch in the page header.
+   *
+   * When true, the shell mounts an icon-only `<CoachLaunchButton>` at
+   * the top-right of the header, vertically aligned with the heading, so
+   * "Coach fragen" reads as a header action rather than a foot-of-page
+   * button. Every routed category page passes it; the mother page and
+   * empty-state branches omit it. The button self-gates on the Coach
+   * feature flag + per-user opt-out, so a disabled-Coach tenant shows
+   * nothing.
+   */
+  coachLaunch?: boolean;
   /**
    * v1.8.5 W4b — a "show all readings" entry rendered at the foot of the
    * page, after the chart + cards. Sub-pages pass the metric's
@@ -100,6 +114,7 @@ export function SubPageShell({
   focusOnMount = false,
   statStrip,
   diversityNudge,
+  coachLaunch = false,
   showAllValuesType,
   children,
 }: SubPageShellProps) {
@@ -144,18 +159,26 @@ export function SubPageShell({
           >
             {title}
           </h1>
-          {explainerMetric ? (
-            <MetricExplainer metric={explainerMetric} />
-          ) : null}
+          {/* v1.8.6 — the diversity nudge now rides the heading as a
+              `Lightbulb` glyph (the node self-gates to nothing when the
+              spread is healthy), replacing the old inline block. */}
+          {diversityNudge}
           {badge ? (
             <Badge variant="outline" className="border text-xs">
               {badge}
             </Badge>
           ) : null}
+          {/* v1.8.6 — Coach launch sits top-right at heading height as an
+              icon. `ml-auto` pushes it to the row's trailing edge so it
+              aligns with the title regardless of badge / glyph presence.
+              The button self-gates on the Coach flag + per-user opt-out. */}
+          {coachLaunch ? (
+            <CoachLaunchButton variant="icon" className="ml-auto" />
+          ) : null}
         </div>
         {explainerMetric ? (
-          // v1.8.4 — surface the explainer definition inline, reusing the
-          // exact body string the `?` popover reads.
+          // v1.8.4 — surface the metric's static definition inline,
+          // directly beneath the heading.
           //
           // v1.8.5 W4a — render the explainer body as the *single* caption
           // under the heading. Pre-v1.8.5 both this paragraph and the
@@ -165,6 +188,10 @@ export function SubPageShell({
           // explainer body is the definition, so it wins; the description
           // only renders when no explainer is set (the mother page and any
           // future explainer-less sub-page).
+          //
+          // v1.8.6 — this caption is now the only surface for the
+          // definition; the round `?` popover that used to read the same
+          // string was removed.
           <p
             data-slot="metric-explainer-inline"
             className="text-muted-foreground text-sm leading-relaxed"
@@ -176,23 +203,26 @@ export function SubPageShell({
           <p className="text-muted-foreground text-sm">{description}</p>
         ) : null}
       </header>
-      {/* v1.8.5 W4b — numbers-first stat strip + diversity nudge sit
-          between the header and the chart so the page leads with data,
-          mirroring the Apple Health / Withings detail layout. Both are
-          self-gating (render nothing without data), so the spacing
-          rhythm holds on the empty-state and brand-new-metric paths. */}
+      {/* v1.8.5 W4b — numbers-first stat strip sits between the header
+          and the chart so the page leads with data, mirroring the Apple
+          Health / Withings detail layout. Self-gating (renders nothing
+          without data), so the spacing rhythm holds on the empty-state
+          and brand-new-metric paths.
+          v1.8.6 — the diversity nudge moved up to the heading row. */}
       {statStrip}
-      {diversityNudge}
       {children}
       {/* v1.8.5 W4b — "show all readings" entry at the foot, linking to
-          the dedicated per-metric values subpage. */}
+          the dedicated per-metric values subpage.
+          v1.8.6 — normalised to the `h-10` secondary-button height so it
+          reads as a consistent control now that the foot-of-page Coach
+          button (which set the old visual baseline) has moved to the
+          header. */}
       {showAllValuesType ? (
         <Button
           asChild
           variant="outline"
-          size="sm"
           data-slot="metric-show-all-values"
-          className="w-full sm:w-auto"
+          className="h-10 w-full sm:w-auto"
         >
           <Link href={`/insights/values/${showAllValuesType}`}>
             <ListOrdered className="mr-1.5 size-4" aria-hidden="true" />