diff --git a/src/app/api/labs/ocr/commit/__tests__/route.test.ts b/src/app/api/labs/ocr/commit/__tests__/route.test.ts
index e77e0b794..3ab2468ad 100644
--- a/src/app/api/labs/ocr/commit/__tests__/route.test.ts
+++ b/src/app/api/labs/ocr/commit/__tests__/route.test.ts
@@ -21,6 +21,15 @@ vi.mock("@/lib/db", () => ({
 }));
 
 vi.mock("@/lib/auth/session", () => ({ getSession: vi.fn() }));
+const rateLimitMock = vi.hoisted(() => ({ allowed: true }));
+vi.mock("@/lib/rate-limit", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@/lib/rate-limit")>()),
+  checkRecordWriteRateLimit: vi.fn(async () => ({
+    allowed: rateLimitMock.allowed,
+    remaining: rateLimitMock.allowed ? 299 : 0,
+    resetAt: new Date(Date.now() + 60_000),
+  })),
+}));
 const tzMock = vi.hoisted(() => ({ zone: "UTC" }));
 vi.mock("@/lib/tz/resolver", async (importOriginal) => ({
   ...(await importOriginal<typeof import("@/lib/tz/resolver")>()),
@@ -62,6 +71,7 @@ import { prisma } from "@/lib/db";
 import { getSession } from "@/lib/auth/session";
 import { resolveOrMintBiomarker } from "@/lib/labs/biomarker-store";
 import { enqueueReminderSatisfy } from "@/lib/jobs/reminder-satisfy";
+import { checkRecordWriteRateLimit } from "@/lib/rate-limit";
 
 const SESSION_OK = {
   session: { id: "sess-1", expiresAt: new Date(Date.now() + 3_600_000) },
@@ -90,6 +100,7 @@ function postReq(body: unknown): NextRequest {
 beforeEach(() => {
   vi.resetAllMocks();
   tzMock.zone = "UTC";
+  rateLimitMock.allowed = true;
   vi.mocked(getSession).mockResolvedValue(SESSION_OK as never);
   vi.mocked(enqueueReminderSatisfy).mockResolvedValue(undefined as never);
   vi.mocked(prisma.auditLog.create).mockResolvedValue({} as never);
@@ -198,3 +209,24 @@ describe("POST /api/labs/ocr/commit dedup across the user's day", () => {
     expect(prisma.labResult.create).toHaveBeenCalledTimes(1);
   });
 });
+
+describe("POST /api/labs/ocr/commit write ceiling", () => {
+  it("charges the shared per-account record-write bucket", async () => {
+    const res = await POST(postReq({ rows: [numericRow(95)] }));
+    expect(res.status).toBe(200);
+    expect(checkRecordWriteRateLimit).toHaveBeenCalledWith("user-1");
+  });
+
+  it("answers 429 record_write.rate_limited and writes nothing once exhausted", async () => {
+    rateLimitMock.allowed = false;
+    const res = await POST(postReq({ rows: [numericRow(95)] }));
+    expect(res.status).toBe(429);
+    const body = (await res.json()) as {
+      error: string;
+      meta?: { errorCode?: string };
+    };
+    expect(body.meta?.errorCode).toBe("record_write.rate_limited");
+    expect(prisma.labResult.create).not.toHaveBeenCalled();
+    expect(resolveOrMintBiomarker).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/app/api/labs/ocr/commit/route.ts b/src/app/api/labs/ocr/commit/route.ts
index 1066edb69..7e0a00d17 100644
--- a/src/app/api/labs/ocr/commit/route.ts
+++ b/src/app/api/labs/ocr/commit/route.ts
@@ -20,6 +20,7 @@ import { fireAndForget } from "@/lib/logging/fire-and-forget";
 
 import { apiHandler, requireAuth } from "@/lib/api-handler";
 import {
+  apiError,
   apiSuccess,
   getClientIp,
   returnAllZodIssues,
@@ -30,6 +31,7 @@ import { auditLog } from "@/lib/auth/audit";
 import { prisma } from "@/lib/db";
 import { invalidateUserHealthScore } from "@/lib/cache/invalidate";
 import { withIdempotency } from "@/lib/idempotency";
+import { checkRecordWriteRateLimit } from "@/lib/rate-limit";
 import { enqueueReminderSatisfy } from "@/lib/jobs/reminder-satisfy";
 import { emitDataArrival } from "@/lib/arrivals/emit-shared";
 import { resolveOrMintBiomarker } from "@/lib/labs/biomarker-store";
@@ -136,6 +138,17 @@ function inBatchKey(row: OcrCommitRow, tz: string): string {
 async function commitOcrRows(request: NextRequest) {
   const { user } = await requireAuth();
 
+  // Shared per-account write ceiling, the same bucket every other lab write
+  // charges (`POST /api/labs`, `POST /api/biomarkers`). A commit can write a
+  // whole report's rows and mint markers on the way, so it was the one lab
+  // write a looping client could repeat without any ceiling.
+  const writeRl = await checkRecordWriteRateLimit(user.id);
+  if (!writeRl.allowed) {
+    return apiError("Too many writes, try again later", 429, {
+      errorCode: "record_write.rate_limited",
+    });
+  }
+
   const { data: body, error: jsonError } = await safeJson(request, {
     maxBytes: 256 * 1024,
   });