fix(glucose): state band edges in the reader's glucose unit

The time-in-range labels in the doctor report, the target caption on
the glucose panel, the glucose page description and the fasting
explainer printed fixed mg/dL figures, so a reader on mmol/L saw
"Low (< 70 mg/dL)" beside values in mmol/L.

The cut-points now live in one place (`GLUCOSE_TIR_CUT_POINTS`,
`GLUCOSE_FASTING_CUT_POINTS`) with the SI figure each guideline prints,
the analytics engine counts its bands from the same constants, and
every sentence takes the band edges and unit as parameters through
`glucoseBandParams`, formatted with the reader's number format.

The unit-preference guard now also reads the locale bundles: a string
that names mg/dL or mmol/L fails unless it is allowlisted with a
reason.

Refs #1067

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

@@ -2,6 +2,8 @@ import { describe, it, expect, vi } from "vitest";
 import { renderToStaticMarkup } from "react-dom/server";
 
 import { I18nProvider } from "@/lib/i18n/context";
+import { glucoseBandParams } from "@/lib/glucose";
+import { makeFormatters } from "@/lib/format-locale";
 import { SubPageShell } from "../sub-page-shell";
 
 vi.mock("next/navigation", () => ({
@@ -68,6 +70,27 @@ describe("<SubPageShell>", () => {
     );
   });
 
+  it("fills the explainer's figures from the explainer parameters", () => {
+    // The glucose definition names the fasting cut-points; a reader on
+    // mmol/L reads them in mmol/L, never a fixed "100 mg/dL".
+    const html = render(
+      <SubPageShell
+        title="Blood glucose"
+        explainerMetric="bloodGlucose"
+        explainerParams={glucoseBandParams(
+          "mmol/L",
+          makeFormatters("en", "UTC", "AUTO", "AUTO").number,
+        )}
+      >
+        <span />
+      </SubPageShell>,
+    );
+    expect(html).toContain(
+      "a fasting reading under 5.6 mmol/L is normal, 5.6–6.9 is prediabetes, and 7.0 or above",
+    );
+    expect(html).not.toContain("{");
+  });
+
   it("no longer paints the round `?` explainer trigger next to the heading", () => {
     const html = render(
       <SubPageShell title="Blood pressure" explainerMetric="bloodPressure">

src/components/insights/glucose/__tests__/glucose-clinical-panel.test.tsx

@@ -148,6 +148,30 @@ describe("<GlucoseClinicalPanel> asserted state", () => {
     expect(html).toContain("J-index");
   });
 
+  it("states the target band in the reader's unit and number format", () => {
+    // The caption used to print "70–180 mg/dL" to every reader, beside
+    // values the panel had already converted to mmol/L.
+    authMock.mockReturnValue({
+      user: { glucoseUnit: "mmol/L" },
+      isAuthenticated: true,
+    });
+    analyticsMock.mockReturnValue({
+      isLoading: false,
+      data: { glucoseClinical: assertedClinical(), glucoseByContext: {} },
+    });
+    const de = render(<GlucoseClinicalPanel />, "de");
+    expect(de).toContain("(3,9–10,0 mmol/L ist das Ziel)");
+    expect(de).not.toMatch(/mg\/dl/i);
+
+    authMock.mockReturnValue({
+      user: { glucoseUnit: "mg/dL" },
+      isAuthenticated: true,
+    });
+    expect(render(<GlucoseClinicalPanel />)).toContain(
+      "(70–180 mg/dL is the target)",
+    );
+  });
+
   it("flags the CV badge unstable at CV% >= 36", () => {
     // wide spread → CV well above 36
     const values = Array.from({ length: 20 }, (_, i) =>

src/components/insights/glucose/glucose-clinical-panel.tsx

@@ -12,8 +12,12 @@ import { LearnMoreLink } from "@/components/ui/learn-more-link";
 import { Skeleton } from "@/components/ui/skeleton";
 import { useAuth } from "@/hooks/use-auth";
 import { useAnalyticsQuery } from "@/lib/queries/use-analytics-query";
-import { useTranslations } from "@/lib/i18n/context";
-import { convertGlucose, resolveGlucoseUnit } from "@/lib/glucose";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
+import {
+  convertGlucose,
+  glucoseBandParams,
+  resolveGlucoseUnit,
+} from "@/lib/glucose";
 import type { DataSummary } from "@/lib/analytics/trends";
 import { GlucoseTirBar } from "./glucose-tir-bar";
 import { GlucoseAdvancedDisclosure } from "./glucose-advanced-disclosure";
@@ -41,6 +45,7 @@ import { GlucoseAdvancedDisclosure } from "./glucose-advanced-disclosure";
 export function GlucoseClinicalPanel() {
   const { user, isAuthenticated } = useAuth();
   const { t } = useTranslations();
+  const fmt = useFormatters();
   const query = useAnalyticsQuery({});
 
   const glucoseUnit = resolveGlucoseUnit(user?.glucoseUnit ?? null);
@@ -158,7 +163,10 @@ export function GlucoseClinicalPanel() {
             </div>
             <GlucoseTirBar distribution={dist} />
             <p className="text-muted-foreground text-xs">
-              {t("insights.bloodGlucose.clinical.tir.caption")}
+              {t(
+                "insights.bloodGlucose.clinical.tir.caption",
+                glucoseBandParams(glucoseUnit, fmt.number),
+              )}
             </p>
           </section>
         ) : null}

src/components/insights/healthkit-metric-page.tsx

@@ -153,6 +153,8 @@ export interface HealthKitMetricPageProps {
    * Resolves `insights.subPage.explainer.<explainerMetric>{Title,Body}`.
    */
   explainerMetric?: string;
+  /** Interpolation values for the explainer sentence (`SubPageShell`). */
+  explainerParams?: Record<string, string>;
   /**
    * v1.8.5 W5 — when set, renders `<MetricTargetSummary slug=…>` beneath
    * the chart. Used by blood glucose, whose per-context ADA / DDG bands
@@ -227,6 +229,7 @@ export function HealthKitMetricPage({
   coachPrefill,
   valueScale,
   explainerMetric,
+  explainerParams,
   targetSummarySlug,
   statusMetric,
   statIcon,
@@ -334,7 +337,10 @@ export function HealthKitMetricPage({
       : rawSummary;
 
   const title = t(`${i18nPrefix}.title`);
-  const description = t(`${i18nPrefix}.description`);
+  // A description that names its unit ("in mg/dL") reads the resolved one.
+  const description = t(`${i18nPrefix}.description`, {
+    unit: resolvedUnit ?? "",
+  });
 
   // v1.12.7 — in-flight skeleton. The page consumed only `{data, isEmpty}`
   // before, so the ~30 HealthKit sub-pages painted nothing until the
@@ -347,6 +353,7 @@ export function HealthKitMetricPage({
         title={title}
         description={description}
         explainerMetric={explainerMetric}
+        explainerParams={explainerParams}
         statStrip={<StatStripSkeleton />}
       >
         <ChartSkeleton />
@@ -364,6 +371,7 @@ export function HealthKitMetricPage({
         title={title}
         description={description}
         explainerMetric={explainerMetric}
+        explainerParams={explainerParams}
       >
         <QueryErrorRow
           slot="healthkit-metric-error"
@@ -389,6 +397,7 @@ export function HealthKitMetricPage({
         title={title}
         description={description}
         explainerMetric={explainerMetric}
+        explainerParams={explainerParams}
       >
         <MetricEmptyState
           icon={emptyStateIcon}
@@ -406,6 +415,7 @@ export function HealthKitMetricPage({
       title={title}
       description={description}
       explainerMetric={explainerMetric}
+      explainerParams={explainerParams}
       statStrip={
         <MetricStatStrip
           summary={summary}

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

@@ -70,6 +70,11 @@ export interface SubPageShellProps {
    * one- to two-sentence definition, no tap required.
    */
   explainerMetric?: string;
+  /**
+   * Interpolation values for the explainer sentence, for a definition that
+   * names figures in the reader's own unit (the glucose cut-points).
+   */
+  explainerParams?: Record<string, string>;
   /**
    * v1.4.27 MB7 / CF-35 — opt-in programmatic focus on mount.
    *
@@ -155,6 +160,7 @@ export function SubPageShell({
   badge,
   description,
   explainerMetric,
+  explainerParams,
   focusOnMount = false,
   statStrip,
   coachReadStrip,
@@ -385,7 +391,10 @@ export function SubPageShell({
               data-slot="metric-explainer-inline"
               className="text-foreground text-sm leading-relaxed"
             >
-              {t(`insights.subPage.explainer.${explainerMetric}Body`)}
+              {t(
+                `insights.subPage.explainer.${explainerMetric}Body`,
+                explainerParams,
+              )}
             </p>
           ) : null}
           {description && !explainerMetric ? (