fix(targets): hold below a default band for load measures and above the band for one-sided measures

src/lib/openapi/routes/trend-verdict.ts

@@ -13,7 +13,7 @@ export const trendVerdict = z
     direction: z
       .enum(["up-good", "up-bad", "neutral", "hold"])
       .describe(
-        "How a change counts: `up-good` a rise is progress, `up-bad` a fall is progress, `hold` the value is inside its band so staying is progress, `neutral` no judgement.",
+        "How a change counts: `up-good` a rise is progress, `up-bad` a fall is progress, `hold` staying is progress and a move either way is no setback, `neutral` no judgement. `hold` covers a value inside its band, a blood pressure, resting pulse or body fat below a profile-default band (a default's lower edge is no goal; below the person's own target a rise stays `up-good`), and steps or oxygen saturation above their band (more is never worse).",
       ),
     targetPosition: z
       .enum(["below", "inside", "above"])

src/lib/targets/__tests__/trend-verdict.test.ts

@@ -36,6 +36,9 @@ describe("resolveTrendVerdict against the person's own target", () => {
     expect(trendSentimentOf(4, v)).toBe("negative");
   });
 
+  // A target the person set themselves is a goal in both directions: below
+  // it, climbing back up is what they asked for. This stays `up-good` even
+  // for the load measures, unlike the profile-default case further down.
   it("calls the same rise below the target progress", () => {
     const v = verdict("BLOOD_PRESSURE_SYS", 108, OWN_BP);
     expect(v).toEqual({
@@ -112,6 +115,28 @@ describe("resolveTrendVerdict against a profile default", () => {
     expect(verdict("BODY_FAT", 30).basis).toBe("metric_default");
   });
 
+  // A default band's lower edge is a population convention, not a goal. A
+  // low blood pressure, resting pulse or body fat against a band nobody chose
+  // holds: its fall is never painted as a setback.
+  it("holds below a default band for the load measures", () => {
+    expect(verdict("BLOOD_PRESSURE_SYS", 108, null, MAN_41)).toEqual({
+      direction: "hold",
+      targetPosition: "below",
+      basis: "profile_default",
+    });
+    expect(verdict("BLOOD_PRESSURE_DIA", 62, null, MAN_41).direction).toBe(
+      "hold",
+    );
+    for (const key of ["PULSE", "RESTING_HEART_RATE"]) {
+      const v = verdict(key, 45, null, MAN_41);
+      expect(v).toMatchObject({ direction: "hold", targetPosition: "below" });
+      expect(trendSentimentOf(-3, v)).toBe("neutral");
+    }
+    expect(
+      verdict("BODY_FAT", 5, null, { ...MAN_41, gender: "MALE" }),
+    ).toMatchObject({ direction: "hold", targetPosition: "below" });
+  });
+
   it("prefers the person's own target over the profile default", () => {
     expect(verdict("BLOOD_PRESSURE_SYS", 125, OWN_BP, MAN_41).basis).toBe(
       "personal_target",
@@ -119,6 +144,29 @@ describe("resolveTrendVerdict against a profile default", () => {
   });
 });
 
+describe("one-sided measures", () => {
+  it("never calls steps above the own target a setback", () => {
+    const own = { ACTIVITY_STEPS: { min: 8000, max: 12_000 } };
+    const v = verdict("ACTIVITY_STEPS", 15_000, own);
+    expect(v).toEqual({
+      direction: "hold",
+      targetPosition: "above",
+      basis: "personal_target",
+    });
+    expect(trendSentimentOf(2000, v)).not.toBe("negative");
+    expect(trendSentimentOf(-2000, v)).not.toBe("negative");
+    expect(verdict("ACTIVITY_STEPS", 5000, own).direction).toBe("up-good");
+  });
+
+  it("never calls oxygen saturation above the own target a setback", () => {
+    const own = { OXYGEN_SATURATION: { min: 92, max: 96 } };
+    expect(verdict("OXYGEN_SATURATION", 98, own)).toMatchObject({
+      direction: "hold",
+      targetPosition: "above",
+    });
+  });
+});
+
 describe("resolveTrendVerdict metric defaults", () => {
   it.each([
     ["ACTIVITY_STEPS", "up-good"],

src/lib/targets/trend-verdict.ts

@@ -17,6 +17,17 @@
  *       below the band  → a rise is progress   (`up-good`)
  *       above the band  → a fall is progress   (`up-bad`)
  *       inside the band → holding is progress  (`hold`)
+ *   - two exceptions to "below / above":
+ *       a low reading of a load measure (blood pressure, resting pulse, body
+ *       fat) against a band nobody chose is `hold`, not `up-good`. A
+ *       default band's lower edge is a population convention, not a goal:
+ *       a well-trained resting pulse of 48 or a systolic of 108 is not
+ *       something to climb out of, and painting its fall orange would tell
+ *       the person to raise it. Only a target the person set themselves
+ *       turns "below" into "a rise is progress".
+ *       a one-sided measure (steps, oxygen saturation) above its band is
+ *       `hold`, never `up-bad`: more steps than the target, or a saturation
+ *       above it, is never a setback.
  *   - no band, or no value to place: the metric's own default direction.
  *
  * Weight keeps its own rule (`weight-trend.ts`): only a target the person set
@@ -200,6 +211,39 @@ export function placeAgainstBand(
   return "inside";
 }
 
+/**
+ * Load measures whose default band's lower edge is no goal (see the module
+ * comment): below a profile-default band they hold rather than climb.
+ */
+const LOW_IS_NOT_A_SETBACK: ReadonlySet<ThresholdMetric> = new Set([
+  "BLOOD_PRESSURE_SYS",
+  "BLOOD_PRESSURE_DIA",
+  "PULSE",
+  "BODY_FAT",
+]);
+
+/** Measures where more is never worse: above the band they hold. */
+const ONE_SIDED_UPWARD: ReadonlySet<ThresholdMetric> = new Set([
+  "ACTIVITY_STEPS",
+  "OXYGEN_SATURATION",
+]);
+
+function directionFor(
+  metric: ThresholdMetric,
+  position: TrendTargetPosition,
+  basis: Exclude<TrendVerdictBasis, "metric_default">,
+): TrendDirectionSentiment {
+  if (
+    position === "below" &&
+    basis === "profile_default" &&
+    LOW_IS_NOT_A_SETBACK.has(metric)
+  ) {
+    return "hold";
+  }
+  if (position === "above" && ONE_SIDED_UPWARD.has(metric)) return "hold";
+  return DIRECTION_BY_POSITION[position];
+}
+
 const DIRECTION_BY_POSITION: Record<
   TrendTargetPosition,
   TrendDirectionSentiment
@@ -246,7 +290,7 @@ export function resolveTrendVerdict(
     toUnit ? toUnit(reference) : reference,
   );
   return {
-    direction: DIRECTION_BY_POSITION[position],
+    direction: directionFor(metric, position, personal.basis),
     targetPosition: position,
     basis: personal.basis,
   };