diff --git a/messages/de.json b/messages/de.json
index ed7059ac9..e9e579531 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} hat einen eigenen Impfstoff entfernt",
       "lifeEventCreate": "{name} hat ein Lebensereignis hinzugefügt",
       "lifeEventUpdate": "{name} hat ein Lebensereignis geändert",
-      "lifeEventDelete": "{name} hat ein Lebensereignis entfernt"
+      "lifeEventDelete": "{name} hat ein Lebensereignis entfernt",
+      "biomarkerMerge": "{name} hat Biomarker zusammengeführt"
     },
     "section": {
       "measurements": {
diff --git a/messages/en.json b/messages/en.json
index 317fe14df..712ef3e10 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} removed an own vaccine",
       "lifeEventCreate": "{name} added a life event",
       "lifeEventUpdate": "{name} changed a life event",
-      "lifeEventDelete": "{name} removed a life event"
+      "lifeEventDelete": "{name} removed a life event",
+      "biomarkerMerge": "{name} merged biomarkers"
     },
     "section": {
       "measurements": {
diff --git a/messages/es.json b/messages/es.json
index c14403377..244eeff75 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} quitó una vacuna propia",
       "lifeEventCreate": "{name} añadió un acontecimiento vital",
       "lifeEventUpdate": "{name} cambió un acontecimiento vital",
-      "lifeEventDelete": "{name} eliminó un acontecimiento vital"
+      "lifeEventDelete": "{name} eliminó un acontecimiento vital",
+      "biomarkerMerge": "{name} combinó biomarcadores"
     },
     "section": {
       "measurements": {
diff --git a/messages/fr.json b/messages/fr.json
index 172d45319..c99baa24b 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} a retiré un vaccin personnel",
       "lifeEventCreate": "{name} a ajouté un événement de vie",
       "lifeEventUpdate": "{name} a modifié un événement de vie",
-      "lifeEventDelete": "{name} a supprimé un événement de vie"
+      "lifeEventDelete": "{name} a supprimé un événement de vie",
+      "biomarkerMerge": "{name} a fusionné des biomarqueurs"
     },
     "section": {
       "measurements": {
diff --git a/messages/it.json b/messages/it.json
index 725cabf55..e1f8f751d 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} ha rimosso un vaccino personale",
       "lifeEventCreate": "{name} ha aggiunto un evento della vita",
       "lifeEventUpdate": "{name} ha modificato un evento della vita",
-      "lifeEventDelete": "{name} ha rimosso un evento della vita"
+      "lifeEventDelete": "{name} ha rimosso un evento della vita",
+      "biomarkerMerge": "{name} ha unito dei biomarcatori"
     },
     "section": {
       "measurements": {
diff --git a/messages/ko.json b/messages/ko.json
index 93077aa28..806768ceb 100644
--- a/messages/ko.json
+++ b/messages/ko.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} 님이 직접 추가한 백신을 삭제했어요",
       "lifeEventCreate": "{name} 님이 삶의 사건을 추가했어요",
       "lifeEventUpdate": "{name} 님이 삶의 사건을 수정했어요",
-      "lifeEventDelete": "{name} 님이 삶의 사건을 삭제했어요"
+      "lifeEventDelete": "{name} 님이 삶의 사건을 삭제했어요",
+      "biomarkerMerge": "{name} 님이 바이오마커를 합쳤어요"
     },
     "section": {
       "measurements": {
diff --git a/messages/pl.json b/messages/pl.json
index 3b7ea5962..f5fab9232 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -12061,7 +12061,8 @@
       "customVaccineDelete": "{name} usunął własną szczepionkę",
       "lifeEventCreate": "{name} dodał wydarzenie życiowe",
       "lifeEventUpdate": "{name} zmienił wydarzenie życiowe",
-      "lifeEventDelete": "{name} usunął wydarzenie życiowe"
+      "lifeEventDelete": "{name} usunął wydarzenie życiowe",
+      "biomarkerMerge": "{name} scalił biomarkery"
     },
     "section": {
       "measurements": {
diff --git a/src/app/api/export/__tests__/per-type-routes.test.ts b/src/app/api/export/__tests__/per-type-routes.test.ts
index bd0a478da..115bf4bc6 100644
--- a/src/app/api/export/__tests__/per-type-routes.test.ts
+++ b/src/app/api/export/__tests__/per-type-routes.test.ts
@@ -86,6 +86,8 @@ vi.mock("@/lib/db", () => ({
     // helper now also reads (`buildRecordsBackupSection`).
     labResult: { findMany: vi.fn() },
     biomarker: { findMany: vi.fn() },
+    biomarkerAlias: { findMany: vi.fn() },
+    biomarkerMerge: { findMany: vi.fn() },
     illnessEpisode: { findMany: vi.fn() },
     allergy: { findMany: vi.fn() },
     familyHistoryEntry: { findMany: vi.fn() },
@@ -135,6 +137,8 @@ beforeEach(() => {
   // `resetAllMocks` clears the inline defaults, and the full-backup payload
   // builder reads these unconditionally.
   vi.mocked(prisma.nutrientIntakeDay.findMany).mockResolvedValue([] as never);
+  vi.mocked(prisma.biomarkerAlias.findMany).mockResolvedValue([] as never);
+  vi.mocked(prisma.biomarkerMerge.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.medicationCategoryLabel.findMany).mockResolvedValue(
     [] as never,
   );
diff --git a/src/app/api/export/__tests__/soft-delete-filter.test.ts b/src/app/api/export/__tests__/soft-delete-filter.test.ts
index 288b99d8e..edbfc9d0b 100644
--- a/src/app/api/export/__tests__/soft-delete-filter.test.ts
+++ b/src/app/api/export/__tests__/soft-delete-filter.test.ts
@@ -67,6 +67,8 @@ vi.mock("@/lib/db", () => ({
     cycleDayLog: { findMany: vi.fn() },
     labResult: { findMany: vi.fn() },
     biomarker: { findMany: vi.fn() },
+    biomarkerAlias: { findMany: vi.fn() },
+    biomarkerMerge: { findMany: vi.fn() },
     allergy: { findMany: vi.fn() },
     familyHistoryEntry: { findMany: vi.fn() },
     workout: { findMany: vi.fn() },
@@ -205,6 +207,8 @@ beforeEach(() => {
   vi.mocked(prisma.cycleDayLog.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.labResult.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.biomarker.findMany).mockResolvedValue([] as never);
+  vi.mocked(prisma.biomarkerAlias.findMany).mockResolvedValue([] as never);
+  vi.mocked(prisma.biomarkerMerge.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.allergy.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.familyHistoryEntry.findMany).mockResolvedValue([] as never);
   vi.mocked(prisma.workout.findMany).mockResolvedValue([] as never);
diff --git a/src/app/api/export/encrypted/__tests__/route.test.ts b/src/app/api/export/encrypted/__tests__/route.test.ts
index a96e6ac92..7ea794bdd 100644
--- a/src/app/api/export/encrypted/__tests__/route.test.ts
+++ b/src/app/api/export/encrypted/__tests__/route.test.ts
@@ -77,6 +77,8 @@ vi.mock("@/lib/db", () => ({
     // builder now also reads (`buildRecordsBackupSection`).
     labResult: { findMany: vi.fn().mockResolvedValue([]) },
     biomarker: { findMany: vi.fn().mockResolvedValue([]) },
+    biomarkerAlias: { findMany: vi.fn().mockResolvedValue([]) },
+    biomarkerMerge: { findMany: vi.fn().mockResolvedValue([]) },
     illnessEpisode: { findMany: vi.fn().mockResolvedValue([]) },
     allergy: { findMany: vi.fn().mockResolvedValue([]) },
     familyHistoryEntry: { findMany: vi.fn().mockResolvedValue([]) },
diff --git a/src/components/labs/biomarker-merge-sheet.tsx b/src/components/labs/biomarker-merge-sheet.tsx
index 2a86ad0d3..8fd26f9f7 100644
--- a/src/components/labs/biomarker-merge-sheet.tsx
+++ b/src/components/labs/biomarker-merge-sheet.tsx
@@ -16,6 +16,7 @@ import { useMutation, useQueryClient } from "@tanstack/react-query";
 import { toast } from "sonner";
 import { Loader2 } from "lucide-react";
 
+import { toastWrittenOutcome } from "@/components/outcome/outcome-toast";
 import { Button } from "@/components/ui/button";
 import { Checkbox } from "@/components/ui/checkbox";
 import { Label } from "@/components/ui/label";
@@ -71,7 +72,8 @@ export function BiomarkerMergeSheet({
         setPreview(result);
         return;
       }
-      toast.success(
+      toastWrittenOutcome(
+        "success",
         tCount("labs.merge.doneToast", result.movedReadings, {
           name: result.target.name,
         }),
diff --git a/src/lib/record-activity/activity-verb.ts b/src/lib/record-activity/activity-verb.ts
index f370de57e..648b6bcee 100644
--- a/src/lib/record-activity/activity-verb.ts
+++ b/src/lib/record-activity/activity-verb.ts
@@ -179,6 +179,8 @@ export function recordActivityVerbLine(
       return t("recordSharing.activityVerb.biomarkerUpdate", { name });
     case "biomarker.delete":
       return t("recordSharing.activityVerb.biomarkerDelete", { name });
+    case "labs.biomarker.merge":
+      return t("recordSharing.activityVerb.biomarkerMerge", { name });
 
     case "allergy.update":
       return t("recordSharing.activityVerb.allergyUpdate", { name });
diff --git a/tests/integration/biomarker-merge.test.ts b/tests/integration/biomarker-merge.test.ts
index f434aab7f..87ac6b667 100644
--- a/tests/integration/biomarker-merge.test.ts
+++ b/tests/integration/biomarker-merge.test.ts
@@ -97,10 +97,9 @@ async function merge(
   body: { sourceIds: string[]; dryRun?: boolean },
 ) {
   const { POST } = await import("@/app/api/biomarkers/[id]/merge/route");
-  return POST(
-    json(body, `http://localhost/api/biomarkers/${targetId}/merge`),
-    { params: Promise.resolve({ id: targetId }) },
-  );
+  return POST(json(body, `http://localhost/api/biomarkers/${targetId}/merge`), {
+    params: Promise.resolve({ id: targetId }),
+  });
 }
 
 async function tableCounts() {
@@ -172,9 +171,8 @@ describe("POST /api/biomarkers/{id}/merge", () => {
     expect(detail.data.meta.total).toBe(42);
 
     // The doctor report: one line, counted 42, under the marker's name.
-    const { loadLabResults } = await import(
-      "@/lib/doctor-report/clinical-records"
-    );
+    const { loadLabResults } =
+      await import("@/lib/doctor-report/clinical-records");
     const report = await loadLabResults(USER_ID, daysAgo(1000), new Date());
     expect(report).toHaveLength(1);
     expect(report![0]).toMatchObject({
@@ -206,14 +204,18 @@ describe("POST /api/biomarkers/{id}/merge", () => {
         if (!page.nextCursor) break;
         offset += page.readings!.length;
       }
-      expect(total.reduce((a, b) => a + b, 0), analyte).toBe(42);
+      expect(
+        total.reduce((a, b) => a + b, 0),
+        analyte,
+      ).toBe(42);
     }
 
     // The source is gone, its old id leads to the target, and the reading's
     // printed name survived.
     const prisma = getPrismaClient();
-    expect(await prisma.biomarker.findUnique({ where: { id: source.id } }))
-      .toBeNull();
+    expect(
+      await prisma.biomarker.findUnique({ where: { id: source.id } }),
+    ).toBeNull();
     const { GET: getMarker } = await import("@/app/api/biomarkers/[id]/route");
     const stale = await getMarker(
       new NextRequest(`http://localhost/api/biomarkers/${source.id}`),
@@ -442,9 +444,11 @@ describe("POST /api/biomarkers/{id}/merge", () => {
       "Ferr",
       "Ferritin (Serum)",
     ]);
-    expect(await getPrismaClient().labResult.count({
-      where: { biomarkerId: c.id },
-    })).toBe(3);
+    expect(
+      await getPrismaClient().labResult.count({
+        where: { biomarkerId: c.id },
+      }),
+    ).toBe(3);
   });
 });
 
@@ -469,7 +473,9 @@ describe("aliases on the marker", () => {
       },
     });
 
-    const res = await put(alp.id, { aliases: ["Alk.P", "AP", "alkaline phosphatase"] });
+    const res = await put(alp.id, {
+      aliases: ["Alk.P", "AP", "alkaline phosphatase"],
+    });
     expect(res.status).toBe(200);
     expect((await res.json()).data.aliases).toEqual(["Alk.P", "AP"]);
     const rows = await prisma.biomarkerAlias.findMany({
@@ -712,9 +718,9 @@ describe("a spelling resolves on its own once chosen", () => {
       where: { id: ref.recordId },
     });
     expect(reading.biomarkerId).toBe(alp.id);
-    expect(
-      (await prisma.biomarkerAlias.findFirstOrThrow({})).name,
-    ).toBe("Alk. Phosph.");
+    expect((await prisma.biomarkerAlias.findFirstOrThrow({})).name).toBe(
+      "Alk. Phosph.",
+    );
 
     const again = serialiseFact(fact, await loadMarkerIndex(prisma, USER_ID));
     expect(again).toMatchObject({ biomarkerId: alp.id, matchKind: "alias" });