diff --git a/App/app/(portal)/po/[id]/receipt/actions.ts b/App/app/(portal)/po/[id]/receipt/actions.ts
index aa227f9..1d045a0 100644
--- a/App/app/(portal)/po/[id]/receipt/actions.ts
+++ b/App/app/(portal)/po/[id]/receipt/actions.ts
@@ -109,7 +109,12 @@ export async function confirmReceipt({
       status: newStatus,
       closedAt: newStatus === "CLOSED" ? new Date() : undefined,
       receipt: notes
-        ? { create: { storageKey: "", fileName: "no-file", notes } }
+        ? {
+            upsert: {
+              create: { storageKey: "", fileName: "no-file", notes },
+              update: { notes },
+            },
+          }
         : undefined,
       actions: {
         create: {
diff --git a/App/tests/integration/confirm-receipt.test.ts b/App/tests/integration/confirm-receipt.test.ts
new file mode 100644
index 0000000..895a40a
--- /dev/null
+++ b/App/tests/integration/confirm-receipt.test.ts
@@ -0,0 +1,197 @@
+/**
+ * Integration tests for the confirmReceipt server action.
+ * Covers: full receipt, partial receipt, upsert notes on repeated confirmation,
+ * and permission guards.
+ */
+import { vi, describe, it, expect, beforeAll, afterEach } from "vitest";
+
+vi.mock("@/auth", () => ({ auth: vi.fn() }));
+vi.mock("next/cache", () => ({ revalidatePath: vi.fn() }));
+vi.mock("@/lib/notifier", () => ({ notify: vi.fn() }));
+
+import { auth } from "@/auth";
+import { db } from "@/lib/db";
+import { createPo } from "@/app/(portal)/po/new/actions";
+import { approvePo } from "@/app/(portal)/approvals/[id]/actions";
+import { processPayment, markPaid } from "@/app/(portal)/payments/actions";
+import { confirmReceipt } from "@/app/(portal)/po/[id]/receipt/actions";
+import {
+  makeSession,
+  getSeedUser,
+  getSeedVessel,
+  getSeedAccount,
+  makePoForm,
+  deletePosByTitle,
+} from "./helpers";
+
+const PREFIX = "INTTEST_RECEIPT_";
+const TODAY = new Date().toISOString().slice(0, 10);
+
+let techId: string;
+let managerId: string;
+let accountsId: string;
+let vesselId: string;
+let accountId: string;
+
+beforeAll(async () => {
+  const [tech, mgr, acct, vessel, account] = await Promise.all([
+    getSeedUser("tech@pelagia.local"),
+    getSeedUser("manager@pelagia.local"),
+    getSeedUser("accounts@pelagia.local"),
+    getSeedVessel("MV Sea Breeze"),
+    getSeedAccount("700202"),
+  ]);
+  techId = tech.id;
+  managerId = mgr.id;
+  accountsId = acct.id;
+  vesselId = vessel.id;
+  accountId = account.id;
+});
+
+afterEach(async () => {
+  await deletePosByTitle(PREFIX);
+});
+
+/** Create a PO and drive it to PAID_DELIVERED (fully paid). */
+async function createPaidPo(title: string): Promise<string> {
+  vi.mocked(auth).mockResolvedValue(makeSession(techId, "TECHNICAL"));
+  const form = makePoForm({ title, vesselId, accountId, intent: "submit" });
+  const { id: poId } = (await createPo(form)) as { id: string };
+
+  vi.mocked(auth).mockResolvedValue(makeSession(managerId, "MANAGER"));
+  await approvePo({ poId });
+
+  vi.mocked(auth).mockResolvedValue(makeSession(accountsId, "ACCOUNTS"));
+  await processPayment({ poId });
+  await markPaid({ poId, paymentRef: "NEFT-TEST-RECEIPT", paymentDate: TODAY });
+
+  vi.mocked(auth).mockResolvedValue(makeSession(techId, "TECHNICAL"));
+  return poId;
+}
+
+describe("confirmReceipt — full delivery", () => {
+  it("transitions PAID_DELIVERED to CLOSED when all items delivered", async () => {
+    const poId = await createPaidPo(`${PREFIX}Full`);
+    const result = await confirmReceipt({ poId });
+    expect(result).toEqual({ ok: true, partial: false });
+
+    const po = await db.purchaseOrder.findUnique({ where: { id: poId } });
+    expect(po?.status).toBe("CLOSED");
+    expect(po?.closedAt).not.toBeNull();
+  });
+
+  it("records RECEIPT_CONFIRMED in audit log", async () => {
+    const poId = await createPaidPo(`${PREFIX}Audit`);
+    await confirmReceipt({ poId });
+
+    const action = await db.pOAction.findFirst({
+      where: { poId, actionType: "RECEIPT_CONFIRMED" },
+    });
+    expect(action).not.toBeNull();
+  });
+
+  it("saves delivery notes on the Receipt record", async () => {
+    const poId = await createPaidPo(`${PREFIX}Notes`);
+    await confirmReceipt({ poId, notes: "All items received in good condition." });
+
+    const receipt = await db.receipt.findUnique({ where: { poId } });
+    expect(receipt?.notes).toBe("All items received in good condition.");
+  });
+});
+
+describe("confirmReceipt — partial delivery", () => {
+  it("transitions PAID_DELIVERED to PARTIALLY_CLOSED when some items remain", async () => {
+    const poId = await createPaidPo(`${PREFIX}Partial`);
+    const lineItems = await db.pOLineItem.findMany({ where: { poId } });
+    const deliveries: Record<string, number> = {};
+    for (const li of lineItems) deliveries[li.id] = 0; // deliver nothing
+
+    const result = await confirmReceipt({ poId, deliveries });
+    // delivering 0 of everything → nothingDelivered guard is in the UI, not the action
+    // action still proceeds and computes PARTIALLY_CLOSED (paid but 0 delivered)
+    expect(result).toEqual({ ok: true, partial: true });
+
+    const po = await db.purchaseOrder.findUnique({ where: { id: poId } });
+    // fully paid but nothing delivered → PARTIALLY_CLOSED
+    expect(po?.status).toBe("PARTIALLY_CLOSED");
+  });
+
+  it("returns partial:true for a partial delivery", async () => {
+    const poId = await createPaidPo(`${PREFIX}PartialQty`);
+    const lineItems = await db.pOLineItem.findMany({ where: { poId } });
+    const half = Math.floor(Number(lineItems[0].quantity) / 2);
+    const deliveries = { [lineItems[0].id]: half };
+
+    const result = await confirmReceipt({ poId, deliveries });
+    expect(result).toEqual({ ok: true, partial: true });
+  });
+});
+
+describe("confirmReceipt — repeated notes upsert (regression for partial → full flow)", () => {
+  it("succeeds on second call with notes after first partial confirmation also had notes", async () => {
+    const poId = await createPaidPo(`${PREFIX}Upsert`);
+    const lineItems = await db.pOLineItem.findMany({ where: { poId } });
+    const half = Math.floor(Number(lineItems[0].quantity) / 2);
+    const remaining = Number(lineItems[0].quantity) - half;
+
+    // First confirmation: partial delivery with notes — creates Receipt row
+    const first = await confirmReceipt({
+      poId,
+      notes: "First batch received.",
+      deliveries: { [lineItems[0].id]: half },
+    });
+    expect(first).toEqual({ ok: true, partial: true });
+
+    // Second confirmation: deliver the rest, also with notes — must not throw
+    // (previously crashed due to unique constraint on Receipt.poId when using `create`)
+    const second = await confirmReceipt({
+      poId,
+      notes: "Remaining items received.",
+      deliveries: { [lineItems[0].id]: remaining },
+    });
+    expect(second).toEqual({ ok: true, partial: false });
+
+    const po = await db.purchaseOrder.findUnique({ where: { id: poId } });
+    expect(po?.status).toBe("CLOSED");
+
+    // Notes should reflect the latest confirmation
+    const receipt = await db.receipt.findUnique({ where: { poId } });
+    expect(receipt?.notes).toBe("Remaining items received.");
+  });
+});
+
+describe("confirmReceipt — permission guards", () => {
+  it("rejects non-submitter who is not SUPERUSER", async () => {
+    const poId = await createPaidPo(`${PREFIX}PermFail`);
+
+    const otherTech = await getSeedUser("tech@pelagia.local");
+    // Use a different user id to simulate a different submitter
+    const fakeSession = makeSession(managerId, "TECHNICAL");
+    vi.mocked(auth).mockResolvedValue(fakeSession);
+
+    const result = await confirmReceipt({ poId });
+    expect(result).toHaveProperty("error");
+    void otherTech; // suppress unused warning
+  });
+
+  it("rejects confirmation on a PO in wrong status", async () => {
+    // Create a PO that is still DRAFT (no payment yet)
+    vi.mocked(auth).mockResolvedValue(makeSession(techId, "TECHNICAL"));
+    const form = makePoForm({ title: `${PREFIX}WrongStatus`, vesselId, accountId, intent: "draft" });
+    const { id: poId } = (await createPo(form)) as { id: string };
+
+    const result = await confirmReceipt({ poId });
+    expect(result).toHaveProperty("error");
+  });
+
+  it("returns error when PO does not exist", async () => {
+    const result = await confirmReceipt({ poId: "nonexistent-po-id" });
+    expect(result).toHaveProperty("error");
+  });
+
+  it("returns error when not authenticated", async () => {
+    vi.mocked(auth).mockResolvedValue(null);
+    const result = await confirmReceipt({ poId: "any-id" });
+    expect(result).toHaveProperty("error");
+  });
+});