test(medications): drift-guard between category enum and label-key map

The medication category enum lives in three places (Prisma schema,
MEDICATION_CATEGORY_VALUES, MEDICATION_CATEGORY_KEYS). A new bucket
added to the enum without a matching label key would silently fall
back to categoryOther in <MedicationCard>. Pin the invariant with a
vitest assertion that every non-OTHER value resolves to a distinct
label key, plus a positive check that the fallback still fires for
unknown categories.

src/lib/medications/__tests__/category-label.test.ts

@@ -0,0 +1,52 @@
+/**
+ * v1.4.38 — drift-guard between the validation enum and the label-key
+ * map. The category enum lives in three places (Prisma schema,
+ * `MEDICATION_CATEGORY_VALUES` in the validation module, and the
+ * `MEDICATION_CATEGORY_KEYS` lookup inside `category-label.ts`). If a
+ * new category lands in the enum without a matching label key, the
+ * generic `<MedicationCard>` quietly falls back to `categoryOther`
+ * for the new bucket — a silent UX regression. Pin the invariant
+ * here so the test suite trips before the regression ships.
+ *
+ * Symmetric drift (label key present without an enum entry) is also
+ * undesirable — it's dead code, but more importantly it suggests the
+ * enum dropped a value without removing the lookup, which leaves the
+ * label map advertising a category the rest of the app no longer
+ * understands.
+ */
+import { describe, expect, it } from "vitest";
+
+import { MEDICATION_CATEGORY_VALUES } from "@/lib/validations/medication";
+import { getMedicationCategoryLabel } from "../category-label";
+
+describe("medication category-label drift-guard", () => {
+  it("every MEDICATION_CATEGORY_VALUES entry resolves to a distinct label key", () => {
+    // Use a no-op translator that echoes the key back so we can
+    // distinguish "real key" from the OTHER fallback.
+    const echo = (key: string) => key;
+    const fallback = "medications.categoryOther";
+
+    for (const value of MEDICATION_CATEGORY_VALUES) {
+      const resolved = getMedicationCategoryLabel(value, echo);
+      if (value === "OTHER") {
+        expect(resolved).toBe(fallback);
+        continue;
+      }
+      // Any non-OTHER enum value that resolves to the OTHER key is a
+      // drift bug — the value made it into the enum without a
+      // matching label entry, so the card silently labels the
+      // category as "Sonstige".
+      expect(
+        resolved,
+        `enum value "${value}" falls back to categoryOther — add a key in MEDICATION_CATEGORY_KEYS to cover it`,
+      ).not.toBe(fallback);
+    }
+  });
+
+  it("the fallback path still fires for an unknown category value", () => {
+    const echo = (key: string) => key;
+    expect(getMedicationCategoryLabel("NOT_A_REAL_CATEGORY", echo)).toBe(
+      "medications.categoryOther",
+    );
+  });
+});