fix(insights): plot the trends row and log fevers in the reader's units

Two more surfaces carried a fixed unit. The insights trends row labelled
weight in kg and body temperature in °C for every reader, and plotted
walking distance as raw metres under a km label; its trend caption
said the same. A single transformed series there now takes unit, scale
and offset from the preference, and the caption describes the converted
series against a converted noise floor.

The illness day sheet and timeline showed and took a fever in °C. The
fever is now seeded, typed and shown in the reader's temperature unit
and stored in °C as before.

Refs #1067

src/lib/insights/__tests__/trend-descriptor.test.ts

@@ -106,13 +106,31 @@ describe("computeTrendDescriptor", () => {
 });
 
 describe("numericDescriptorCopy", () => {
+  it("states a preference-bound slot in the unit the caller resolves", () => {
+    const d = computeTrendDescriptor(series([181.6, 178.5]), {
+      absoluteFloor: 0.66,
+      relativeFloor: 0.01,
+      decimals: 1,
+    })!;
+    const copy = numericDescriptorCopy("weight", d, (type) =>
+      type === "WEIGHT" ? "lb" : "?",
+    );
+    expect(copy?.params.unit).toBe(" lb");
+    expect(TREND_SLOT_DESCRIPTOR_META.distance.unitType).toBe(
+      "WALKING_RUNNING_DISTANCE",
+    );
+    expect(TREND_SLOT_DESCRIPTOR_META.body_temp.unitType).toBe(
+      "BODY_TEMPERATURE",
+    );
+  });
+
   it("resolves the rising template with a signed delta and spaced unit", () => {
     const d = computeTrendDescriptor(series([120, 128]), {
       absoluteFloor: 2,
       relativeFloor: 0.02,
       decimals: 0,
     })!;
-    const copy = numericDescriptorCopy("bp", d);
+    const copy = numericDescriptorCopy("bp", d, () => "unused");
     expect(copy?.key).toBe("insights.trendDescriptor.rising");
     expect(copy?.params.delta).toBe("+8");
     expect(copy?.params.unit).toBe(" mmHg");
@@ -124,7 +142,7 @@ describe("numericDescriptorCopy", () => {
       relativeFloor: 0.05,
       decimals: 0,
     })!;
-    const copy = numericDescriptorCopy("steps", d);
+    const copy = numericDescriptorCopy("steps", d, () => "unused");
     expect(copy?.key).toBe("insights.trendDescriptor.rising");
     expect(copy?.params.unit).toBe("");
   });
@@ -135,14 +153,14 @@ describe("numericDescriptorCopy", () => {
       relativeFloor: 0.01,
       decimals: 1,
     })!;
-    const copy = numericDescriptorCopy("weight", d);
+    const copy = numericDescriptorCopy("weight", d, () => "kg");
     expect(copy?.key).toBe("insights.trendDescriptor.falling");
     expect(copy?.params.delta).toBe("−1.4");
   });
 
   it("returns null for a slot with no numeric meta (mood)", () => {
     const d = computeTrendDescriptor(series([3, 4]), MOOD_DESCRIPTOR_CONFIG)!;
-    expect(numericDescriptorCopy("mood", d)).toBeNull();
+    expect(numericDescriptorCopy("mood", d, () => "")).toBeNull();
   });
 
   it("covers every numeric slot in the descriptor meta", () => {
@@ -154,7 +172,7 @@ describe("numericDescriptorCopy", () => {
         relativeFloor: 0,
         decimals: 1,
       })!;
-      expect(numericDescriptorCopy(metric, d)).not.toBeNull();
+      expect(numericDescriptorCopy(metric, d, () => "u")).not.toBeNull();
     }
   });
 });

src/lib/insights/trend-chart-select.ts

@@ -51,7 +51,12 @@ export interface TrendChartConfig {
   types: string[];
   /** Recharts stroke colours, positionally matched to `types`. */
   colors: string[];
-  /** Display unit (chart legend / tooltip). */
+  /**
+   * Display unit (chart legend / tooltip) for a metric no preference
+   * changes. A single-series slot whose type has a display transform
+   * (weight, distance, body temperature) carries none: the renderer takes
+   * the unit, scale and offset from the reader's preference instead.
+   */
   unit?: string;
   /** Y-axis unit label when it differs from the value unit. */
   yAxisUnit?: string;
@@ -114,7 +119,6 @@ export const TREND_CHART_CONFIG: Record<
     kind: "health-chart",
     types: ["WEIGHT"],
     colors: ["var(--chart-1)"],
-    unit: "kg",
     titleKey: "charts.weight",
     captionKey: "insights.trendsRow.caption.weight",
     annotationKey: "weight",
@@ -212,8 +216,6 @@ export const TREND_CHART_CONFIG: Record<
     kind: "health-chart",
     types: ["WALKING_RUNNING_DISTANCE"],
     colors: ["var(--chart-4)"],
-    unit: "km",
-    yAxisUnit: "km",
     titleKey: "charts.distance",
     captionKey: "insights.trendsRow.caption.distance",
     detailHref: "/insights/walking-distance",
@@ -234,8 +236,6 @@ export const TREND_CHART_CONFIG: Record<
     kind: "health-chart",
     types: ["BODY_TEMPERATURE"],
     colors: ["var(--destructive)"],
-    unit: "°C",
-    yAxisUnit: "°C",
     titleKey: "charts.bodyTemperature",
     captionKey: "insights.trendsRow.caption.body_temp",
     detailHref: "/insights/body-temperature",

src/lib/insights/trend-descriptor.ts

@@ -140,8 +140,17 @@ export function computeTrendDescriptor(
  * dedicated copy rather than the numeric `{delta} {unit}` template.
  */
 export interface TrendSlotDescriptorMeta {
-  /** Display unit interpolated into the numeric descriptor template. */
-  unit: string;
+  /**
+   * Display unit interpolated into the numeric descriptor template, for a
+   * metric no preference changes.
+   */
+  unit?: string;
+  /**
+   * For a metric whose unit follows the reader's preference: the
+   * measurement type the caller resolves the unit of (and converts the
+   * series and the noise floor through) before describing it.
+   */
+  unitType?: string;
   config: TrendDescriptorConfig;
 }
 
@@ -154,7 +163,7 @@ export const TREND_SLOT_DESCRIPTOR_META: Record<
     config: { absoluteFloor: 2, relativeFloor: 0.02, decimals: 0 },
   },
   weight: {
-    unit: "kg",
+    unitType: "WEIGHT",
     config: { absoluteFloor: 0.3, relativeFloor: 0.01, decimals: 1 },
   },
   pulse: {
@@ -186,7 +195,7 @@ export const TREND_SLOT_DESCRIPTOR_META: Record<
     config: { absoluteFloor: 1, relativeFloor: 0.1, decimals: 0 },
   },
   distance: {
-    unit: "km",
+    unitType: "WALKING_RUNNING_DISTANCE",
     config: { absoluteFloor: 0.3, relativeFloor: 0.05, decimals: 1 },
   },
   vo2_max: {
@@ -194,7 +203,7 @@ export const TREND_SLOT_DESCRIPTOR_META: Record<
     config: { absoluteFloor: 0.5, relativeFloor: 0.02, decimals: 1 },
   },
   body_temp: {
-    unit: "°C",
+    unitType: "BODY_TEMPERATURE",
     config: { absoluteFloor: 0.2, relativeFloor: 0.005, decimals: 1 },
   },
 };
@@ -231,9 +240,12 @@ export interface TrendDescriptorCopy {
 export function numericDescriptorCopy(
   metric: string,
   descriptor: TrendDescriptor,
+  /** Resolves a `unitType` slot's unit under the reader's preference. */
+  unitFor: (type: string) => string,
 ): TrendDescriptorCopy | null {
   const meta = TREND_SLOT_DESCRIPTOR_META[metric];
   if (!meta) return null;
+  const unit = meta.unitType ? unitFor(meta.unitType) : (meta.unit ?? "");
 
   // Signed, formatted magnitude (e.g. "+8", "-1.4"). `stable` still
   // carries its small delta so the caption can read "stable (±0 …)" if a
@@ -255,7 +267,7 @@ export function numericDescriptorCopy(
       // reads "({delta}{unit})" → "(+8 mmHg)" with a unit, "(+1200)"
       // without one — no dangling space inside the parens for unit-less
       // metrics (steps, flights).
-      unit: meta.unit ? ` ${meta.unit}` : "",
+      unit: unit ? ` ${unit}` : "",
     },
   };
 }