fix(targets): no adult weight and BMI bands on a child's record

Now that the BMI chart draws inside a managed record, a child's normal
BMI sat in the red under-17 band, and the weight page painted the adult
WHO band (about 26 to 35 kg for 118 cm), so a healthy 21 kg read as
underweight. The release's own weight-band test pinned that band.

No band here knows a child's age yet. For a record under 18, or a
managed record with no date of birth, the targets read names no WHO
weight range, no BMI range and no category; the record's own weight
target still shows, and the values and the chart stay. The BMI chart
and the weight band draw only what the server names. The weight-band
test now uses an adult height and gains the child case.

The targets builder and the vitals builder grow by two lines each for
the flag; their size baselines are raised to match.

src/app/insights/bmi/__tests__/page.test.tsx

@@ -23,6 +23,7 @@ const state = {
   viewerHeight: null as number | null,
   inSharedRecord: true,
   recordHeight: 118 as number | null,
+  bmiRange: { min: 18.5, max: 24.9 } as { min: number; max: number } | null,
 };
 vi.mock("@/hooks/use-auth", () => ({
   useAuth: () => ({
@@ -41,7 +42,10 @@ vi.mock("@tanstack/react-query", () => ({
     data:
       enabled === false
         ? undefined
-        : { profile: { heightCm: state.recordHeight } },
+        : {
+            targets: [{ type: "BMI", range: state.bmiRange }],
+            profile: { heightCm: state.recordHeight },
+          },
   }),
 }));
 
@@ -61,6 +65,7 @@ describe("/insights/bmi height gate", () => {
     state.viewerHeight = null;
     state.inSharedRecord = true;
     state.recordHeight = 118;
+    state.bmiRange = { min: 18.5, max: 24.9 };
   });
 
   it("reads the record's height inside somebody else's record", () => {
@@ -77,4 +82,20 @@ describe("/insights/bmi height gate", () => {
     state.viewerHeight = null;
     expect(asksForHeight()).toBe(true);
   });
+
+  it("draws the adult bands only where the record's BMI range is named", () => {
+    const chartBands = () => {
+      renderToStaticMarkup(<InsightsBmiPage />);
+      const { children } = shellProps.mock.calls.at(-1)![0] as {
+        children: Array<{ props?: { valueBands?: unknown } }>;
+      };
+      return children.find(
+        (child) => child?.props && "valueBands" in child.props,
+      )?.props?.valueBands;
+    };
+    expect(chartBands()).toBeDefined();
+    // A child's record: the server names no BMI range.
+    state.bmiRange = null;
+    expect(chartBands()).toBeUndefined();
+  });
 });

src/app/insights/bmi/page.tsx

@@ -56,15 +56,21 @@ export default function InsightsBmiPage() {
   const { data: targets } = useQuery({
     queryKey: queryKeys.insightsTargets(),
     queryFn: () =>
-      apiGet<{ profile?: { heightCm: number | null } }>(
-        "/api/insights/targets",
-      ),
-    enabled: isAuthenticated && inSharedRecord,
+      apiGet<{
+        targets: ReadonlyArray<{ type: string; range: unknown }>;
+        profile?: { heightCm: number | null };
+      }>("/api/insights/targets"),
+    enabled: isAuthenticated,
   });
   const heightCm = inSharedRecord
     ? (targets?.profile?.heightCm ?? null)
     : (user?.heightCm ?? null);
   const heightKnown = !inSharedRecord || targets !== undefined;
+  // The adult bands only where the server names the BMI range: it names none
+  // for a child's record, which they do not describe.
+  const bmiBands = targets?.targets.find((entry) => entry.type === "BMI")?.range
+    ? BMI_BANDS
+    : undefined;
 
   // v1.4.27 — BMI is derived from WEIGHT. When no weight readings
   // exist yet, the existing "set your height" branch can never compute
@@ -140,7 +146,7 @@ export default function InsightsBmiPage() {
         colors={["var(--chart-5)"]}
         unit="kg/m²"
         valueMode="bmi"
-        valueBands={BMI_BANDS}
+        valueBands={bmiBands}
         compareBaseline={compareBaseline}
         userTimezone={user?.timezone}
         showDataTable

src/app/insights/weight/__tests__/weight-band.test.ts

@@ -12,11 +12,22 @@ describe("selectWeightBandRange", () => {
   it("builds the WHO band from the record's height", () => {
     const range = selectWeightBandRange({
       targets: [
-        { type: "WEIGHT", range: { min: 25.8, max: 34.7 }, source: "WHO BMI" },
+        { type: "WEIGHT", range: { min: 59.9, max: 81 }, source: "WHO BMI" },
       ],
-      profile: { heightCm: 118 },
+      profile: { heightCm: 180 },
     });
-    expect(range).toEqual(buildWeightRangeFromHeight(118));
+    expect(range).toEqual(buildWeightRangeFromHeight(180));
+  });
+
+  it("paints no adult band behind a child's weights", () => {
+    // A 118 cm child: the server names no WHO range for a record under 18,
+    // where the adult band read a normal 21 kg as underweight.
+    expect(
+      selectWeightBandRange({
+        targets: [{ type: "WEIGHT", range: null, source: "WHO BMI" }],
+        profile: { heightCm: 118 },
+      }),
+    ).toBeNull();
   });
 
   it("paints the record's own target with the override wings", () => {

src/app/insights/weight/weight-band.ts

@@ -24,14 +24,16 @@ export interface WeightTargetsSlice {
  * record's own target and height, and the reference panel under the chart
  * reads the same payload. The record's own target (`source: "Custom"`) gets
  * the wings `getEffectiveRange` gives every override; otherwise the band is
- * the height-derived WHO one, and with neither there is none.
+ * the height-derived WHO one. Where the server names no range there is none:
+ * no target and no height, or a child's record, which the adult WHO band does
+ * not describe.
  */
 export function selectWeightBandRange(
   data: WeightTargetsSlice | null,
 ): TrafficRange | null {
-  if (!data) return null;
-  const weight = data.targets.find((entry) => entry.type === "WEIGHT");
-  if (weight?.source === "Custom" && weight.range) {
+  const weight = data?.targets.find((entry) => entry.type === "WEIGHT");
+  if (!data || !weight?.range) return null;
+  if (weight.source === "Custom") {
     return getEffectiveRange(
       "WEIGHT",
       { heightCm: null, dateOfBirth: null, gender: null },