fix(insights): say a steady usual value as one figure, not a range of equal ends

src/components/insights/derived/__tests__/coach-read-strip-steady-band.test.tsx

@@ -0,0 +1,72 @@
+import { describe, it, expect, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+
+import { I18nProvider } from "@/lib/i18n/context";
+import { queryKeys } from "@/lib/query-keys";
+import type { CoachReadStripData } from "@/lib/insights/derived/coach-read-shape";
+
+/**
+ * A band whose two ends format to the same figure is a steady value.
+ *
+ * With many identical daily readings the robust band collapses, and the strip
+ * read "Your usual range is 61–61 bpm". It now names the one value instead,
+ * and keeps the placement of today's reading.
+ */
+
+vi.mock("@/hooks/use-auth", () => ({
+  useAuth: () => ({
+    user: { timezone: "UTC", dateOfBirth: null, gender: null },
+    isAuthenticated: true,
+  }),
+}));
+
+vi.mock("@/hooks/use-mounted", () => ({ useMounted: () => true }));
+
+import { CoachReadStrip } from "../coach-read-strip";
+
+const METRIC = "RESTING_HEART_RATE";
+
+function render(data: CoachReadStripData): string {
+  const client = new QueryClient({
+    defaultOptions: { queries: { retry: false, staleTime: Infinity } },
+  });
+  client.setQueryData(queryKeys.insightsCoachRead(METRIC, "en"), data);
+  return renderToStaticMarkup(
+    <QueryClientProvider client={client}>
+      <I18nProvider initialLocale="en">
+        <CoachReadStrip metricType={METRIC} unit="bpm" />
+      </I18nProvider>
+    </QueryClientProvider>,
+  );
+}
+
+function band(
+  low: number,
+  high: number,
+  latest: number,
+  placement: "within" | "above" | "below",
+): CoachReadStripData {
+  return {
+    baseline: { low, high, latest, placement, sampleDays: 30 },
+    learning: false,
+    driver: null,
+  };
+}
+
+describe("CoachReadStrip — steady band", () => {
+  it("names one value when both ends format alike", () => {
+    const markup = render(band(61, 61.04, 61, "within"));
+    expect(markup).not.toContain("61–61");
+    expect(markup).toContain("usually sit at 61");
+  });
+
+  it("keeps the placement for a steady value", () => {
+    expect(render(band(61, 61, 66, "above"))).toContain("is above that");
+    expect(render(band(61, 61, 57, "below"))).toContain("is below that");
+  });
+
+  it("still shows a real range as a range", () => {
+    expect(render(band(58, 64, 61, "within"))).toContain("58–64");
+  });
+});

src/components/insights/derived/coach-read-strip.tsx

@@ -106,8 +106,16 @@ export function CoachReadStrip({
       return t("insights.coach.readStrip.insufficient");
     }
     const { low, high, latest, placement } = data.baseline;
-    const key =
-      placement === "above"
+    // A band whose ends format to the same figure ("61–61 bpm") is a steady
+    // value, not a range; say it as one.
+    const steady = fmt(low) === fmt(high);
+    const key = steady
+      ? placement === "above"
+        ? "insights.coach.readStrip.steadyAbove"
+        : placement === "below"
+          ? "insights.coach.readStrip.steadyBelow"
+          : "insights.coach.readStrip.steadyWithin"
+      : placement === "above"
         ? "insights.coach.readStrip.baselineAbove"
         : placement === "below"
           ? "insights.coach.readStrip.baselineBelow"