feat(coach): carry glucose in the user's display unit

src/lib/ai/coach/__tests__/snapshot-new-metrics.test.ts

@@ -236,6 +236,51 @@ describe("buildCoachSnapshot — Apple Health additive metrics (v1.4.23)", () =>
     expect(out.provenance.metrics).toContain("glucose");
   });
 
+  it("carries glucose in the user's display unit (mmol/L) — v1.16.16", async () => {
+    // A mmol/L-preference user's Coach must read 5.5, not the stored 100.
+    prismaMock.user.findUnique.mockResolvedValue({
+      coachPrefsJson: null,
+      glucoseUnit: "mmol/L",
+    });
+    prismaMock.measurement.findMany.mockResolvedValue([
+      { ...daysAgo(1, 100, "BLOOD_GLUCOSE"), glucoseContext: "FASTING" },
+    ]);
+    const out = await buildCoachSnapshot("user-1", {
+      sources: ["glucose"],
+      window: "last30days",
+    });
+    const snapshot = JSON.parse(out.snapshotJson) as {
+      glucose?: {
+        unit?: string;
+        byContext?: Record<string, { recent?: Array<{ value: number }> }>;
+      };
+    };
+    expect(snapshot.glucose?.unit).toBe("mmol/L");
+    expect(snapshot.glucose?.byContext?.fasting?.recent?.[0]?.value).toBe(5.5);
+  });
+
+  it("keeps mg/dL glucose values byte-identical with a unit token — v1.16.16", async () => {
+    prismaMock.user.findUnique.mockResolvedValue({
+      coachPrefsJson: null,
+      glucoseUnit: "mg/dL",
+    });
+    prismaMock.measurement.findMany.mockResolvedValue([
+      { ...daysAgo(1, 100, "BLOOD_GLUCOSE"), glucoseContext: "FASTING" },
+    ]);
+    const out = await buildCoachSnapshot("user-1", {
+      sources: ["glucose"],
+      window: "last30days",
+    });
+    const snapshot = JSON.parse(out.snapshotJson) as {
+      glucose?: {
+        unit?: string;
+        byContext?: Record<string, { recent?: Array<{ value: number }> }>;
+      };
+    };
+    expect(snapshot.glucose?.unit).toBe("mg/dL");
+    expect(snapshot.glucose?.byContext?.fasting?.recent?.[0]?.value).toBe(100);
+  });
+
   it("caps the workouts block and rolls up per sport", async () => {
     const workouts = Array.from({ length: 25 }, (_, i) => ({
       sportType: i % 2 === 0 ? "RUNNING" : "CYCLING",

src/lib/ai/coach/snapshot.ts

@@ -23,6 +23,7 @@ import {
   type CoachDataCluster,
 } from "@/lib/validations/coach-prefs";
 import { DEFAULT_TIMEZONE } from "@/lib/tz/resolver";
+import { convertGlucose, resolveGlucoseUnit } from "@/lib/glucose";
 import {
   reconstructSleepNights,
   type SleepStageRow,
@@ -481,6 +482,10 @@ async function buildCoachSnapshotImpl(
       // both columns here so a non-cycle account pays no extra round-trip.
       gender: true,
       cycleProfile: { select: { cycleTrackingEnabled: true } },
+      // v1.16.16 — the glucose block converts canonical mg/dL to the user's
+      // display unit so the Coach reads the same number every other surface
+      // shows. Read it on this existing prefs hop (no extra round-trip).
+      glucoseUnit: true,
     },
   });
   const prefs = parseCoachPrefs(prefsRow?.coachPrefsJson);
@@ -494,6 +499,7 @@ async function buildCoachSnapshotImpl(
     clusterDefault,
   );
   const userTz = prefsRow?.timezone ?? DEFAULT_TIMEZONE;
+  const glucoseUnit = resolveGlucoseUnit(prefsRow?.glucoseUnit ?? null);
   const excluded = new Set<CoachExcludeMetric>(prefs.excludeMetrics);
   // v1.4.36 W3 T2 — `medications` and `anthropometrics` are
   // exclude-only toggles (not in `CoachScopeSource`); they gate the
@@ -1317,15 +1323,30 @@ async function buildCoachSnapshotImpl(
       }
       const contexts: Record<string, unknown> = {};
       for (const [ctx, rows] of byContext) {
-        contexts[ctx] = {
-          recent: buildDailyValueRows(rows, recentCutoff, userTz),
-          weekly: bucketWeekly(
-            rows.filter((r) => r.measuredAt < recentCutoff),
-            userTz,
-          ),
-        };
+        // v1.16.16 — glucose is stored canonical mg/dL. A mmol/L-preference
+        // user's Coach must read the same number every other surface shows
+        // (5.5, not 100). Aggregate the per-day / weekly means in raw mg/dL,
+        // then convert each resulting figure ONCE (parity with the series
+        // DTO + detail page + FHIR). mg/dL users stay byte-identical because
+        // the conversion is skipped entirely.
+        const recent = buildDailyValueRows(rows, recentCutoff, userTz).map((d) =>
+          glucoseUnit === "mmol/L"
+            ? { ...d, value: convertGlucose(d.value, glucoseUnit) }
+            : d,
+        );
+        const weekly = bucketWeekly(
+          rows.filter((r) => r.measuredAt < recentCutoff),
+          userTz,
+        ).map((w) =>
+          glucoseUnit === "mmol/L"
+            ? { ...w, mean: convertGlucose(w.mean, glucoseUnit) }
+            : w,
+        );
+        contexts[ctx] = { recent, weekly };
       }
-      snapshot.glucose = { byContext: contexts };
+      // The display unit travels with the block so the prompt renders
+      // "<value> <unit>" and the EVIDENCE BLOCK tags glucose lines correctly.
+      snapshot.glucose = { unit: glucoseUnit, byContext: contexts };
       metrics.add("glucose");
       counts.glucose = glucoseRows.length;
       registerBlock("glucose", "glucose");

src/lib/ai/coach/system-prompt.ts

@@ -213,7 +213,8 @@ ISO-week means.
 - The SNAPSHOT is ADDITIVE. Beyond blood pressure, weight, pulse,
   mood, and medication, it MAY carry body-composition, activity,
   workouts, sleep (with per-stage minutes), glucose (split by
-  context: fasting / postprandial / random / bedtime), mobility &
+  context: fasting / postprandial / random / bedtime, carrying its
+  own display "unit" of mg/dL or mmol/L), mobility &
   gait, and environmental-exposure blocks — but only when the user
   enabled the cluster AND has data. A block that is absent means the
   user has no such data or did not share it; never invent or assume a
@@ -257,7 +258,7 @@ Rules:
   or a day-pin ("Tue 6 May").
 - "value" is a pre-formatted display string ("138/85", "84.2",
   "4.1"). Format mood as N/5 when numeric.
-- "unit" is one of mmHg, kg, bpm, /5, %.
+- "unit" is one of mmHg, kg, bpm, /5, %, mg/dL, mmol/L.
 - "window" is one of last7days, last30days, last90days, allTime;
   omit it for day-level pins.
 - Omit the entire block (no ---KEYVALUES--- line, no ---END--- line)