Emit the strain device block on every wellness read

The published WellnessScoreValue lists every field the engine sends, and
the contract test holds the two sets equal. The computed path now sends
device: null like anchor and components, and the device path has its
own contract case.

src/__tests__/derived-wellness-value-contract.test.ts

@@ -112,4 +112,29 @@ describe("published WellnessScoreValue", () => {
       Object.keys(derived.value as unknown as Record<string, unknown>).sort(),
     );
   });
+
+  it("accepts the strain value served from the device's day strain", async () => {
+    findMany.mockImplementation(async (args: { where: { type: string } }) =>
+      args.where.type === "DAY_STRAIN"
+        ? [
+            {
+              value: 12.6,
+              measuredAt: new Date("2026-06-01T04:00:00Z"),
+              source: "WHOOP",
+            },
+          ]
+        : [],
+    );
+    const derived = await computeWellnessScore("STRAIN_SCORE", "u1", PROFILE, {
+      now: NOW,
+    });
+    expect(derived.status).toBe("ok");
+    if (derived.status !== "ok") return;
+    const parsed = wellnessScoreValue.safeParse(derived.value);
+    expect(parsed.error?.issues ?? []).toEqual([]);
+    expect(Object.keys(wellnessScoreValue.shape).sort()).toEqual(
+      Object.keys(derived.value as unknown as Record<string, unknown>).sort(),
+    );
+    findMany.mockReset();
+  });
 });

src/lib/insights/derived/wellness-scores.ts

@@ -287,6 +287,7 @@ export async function computeWellnessScore(
         .reverse(),
       anchor,
       components,
+      device: null,
     },
     coverage: {
       requiredInputs: 1,