diff --git a/src/app/api/v1/quotes/create/route.test.ts b/src/app/api/v1/quotes/create/route.test.ts
new file mode 100644
index 0000000..f23a880
--- /dev/null
+++ b/src/app/api/v1/quotes/create/route.test.ts
@@ -0,0 +1,183 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { NextRequest } from "next/server";
+
+// Mock the service layer so we can drive createQuote's success /
+// 409 paths without touching PB. The route is a thin wrapper; the
+// service-side branches are exercised here by what the mock returns.
+//
+// We use `importOriginal` so the real `QuoteNumberExistsError` class
+// stays exported — the route catches `instanceof QuoteNumberExistsError`
+// to map the typed error → 409. Without it, `instanceof` always fails
+// and we'd 500 instead of 409.
+const createQuoteMock = vi.fn();
+vi.mock("@/lib/server/quotes-service", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@/lib/server/quotes-service")>();
+  return {
+    ...actual,
+    createQuote: (...args: unknown[]) => createQuoteMock(...args),
+  };
+});
+
+// assertAgentAuth reads AGENT_API_KEY at call time, so we set it
+// in beforeEach. The matching Bearer header is added on each request.
+const AGENT_KEY = "test-agent-key";
+
+import { POST } from "./route";
+
+function makeReq(body: unknown) {
+  return new NextRequest("http://localhost/api/v1/quotes/create", {
+    method: "POST",
+    body: JSON.stringify(body),
+    headers: {
+      "content-type": "application/json",
+      authorization: `Bearer ${AGENT_KEY}`,
+    },
+  });
+}
+
+const baseBody = {
+  customer: "cust-1",
+  company: "co-1",
+  description: "Walk-in for John",
+  validity_days: 30,
+  rfq_number: "RFQ-2026-014",
+  items: [{ description: "Bearing 6205", quantity: 2 }],
+};
+
+beforeEach(() => {
+  createQuoteMock.mockReset();
+  process.env.AGENT_API_KEY = AGENT_KEY;
+});
+
+describe("POST /api/v1/quotes/create", () => {
+  it("forwards the operator-supplied quote_number to the service and returns 201", async () => {
+    createQuoteMock.mockResolvedValueOnce({
+      quote: { id: "q-new", quote_number: "Q-2026-08-007" },
+      customer: { id: "cust-1", customer: "John" },
+      company: { id: "co-1", company: "Acme" },
+      items: [{ id: "qi-1" }],
+      quote_number: "Q-2026-08-007",
+    });
+
+    const res = await POST(
+      makeReq({
+        ...baseBody,
+        quote_number: "Q-2026-08-007",
+        quote_notes: "Why we cannot quote: out of stock",
+      }),
+    );
+    expect(res.status).toBe(201);
+
+    const passed = createQuoteMock.mock.calls[0][0];
+    expect(passed.quote_number).toBe("Q-2026-08-007");
+    expect(passed.rfq_number).toBe("RFQ-2026-014");
+    expect(passed.quote_notes).toBe("Why we cannot quote: out of stock");
+    expect(passed.items).toHaveLength(1);
+
+    const body = await res.json();
+    expect(body.quote_number).toBe("Q-2026-08-007");
+  });
+
+  it("returns 409 with existing_id when the service throws QuoteNumberExistsError", async () => {
+    const { QuoteNumberExistsError } = await import(
+      "@/lib/server/quotes-service"
+    );
+    createQuoteMock.mockRejectedValueOnce(
+      new QuoteNumberExistsError("q-existing-15", "Q-2026-08-007"),
+    );
+
+    const res = await POST(
+      makeReq({ ...baseBody, quote_number: "Q-2026-08-007" }),
+    );
+    expect(res.status).toBe(409);
+
+    const body = await res.json();
+    expect(body.existing_id).toBe("q-existing-15");
+    expect(body.code).toBe("quote_number_exists");
+    expect(body.error).toMatch(/already in use/i);
+  });
+
+  it("falls back from notes → quote_notes (per the route's merge rule)", async () => {
+    createQuoteMock.mockResolvedValueOnce({
+      quote: { id: "q-new", quote_number: "Q-2026-08-008" },
+      customer: { id: "cust-1" },
+      company: null,
+      items: [],
+      quote_number: "Q-2026-08-008",
+    });
+
+    const res = await POST(makeReq({ ...baseBody, notes: "free-text note" }));
+    expect(res.status).toBe(201);
+
+    const passed = createQuoteMock.mock.calls[0][0];
+    // `notes` should map to `quote_notes` when only `notes` is supplied.
+    expect(passed.quote_notes).toBe("free-text note");
+  });
+
+  it("prefers quote_notes over notes when both are supplied", async () => {
+    createQuoteMock.mockResolvedValueOnce({
+      quote: { id: "q-new", quote_number: "Q-2026-08-009" },
+      customer: { id: "cust-1" },
+      company: null,
+      items: [],
+      quote_number: "Q-2026-08-009",
+    });
+
+    const res = await POST(
+      makeReq({
+        ...baseBody,
+        notes: "fallback value",
+        quote_notes: "primary value",
+      }),
+    );
+    expect(res.status).toBe(201);
+
+    const passed = createQuoteMock.mock.calls[0][0];
+    expect(passed.quote_notes).toBe("primary value");
+  });
+
+  it("returns 401 when the Authorization header is missing", async () => {
+    const req = new NextRequest("http://localhost/api/v1/quotes/create", {
+      method: "POST",
+      body: JSON.stringify(baseBody),
+      headers: { "content-type": "application/json" },
+    });
+    const res = await POST(req);
+    expect(res.status).toBe(401);
+    expect(createQuoteMock).not.toHaveBeenCalled();
+  });
+
+  it("returns 400 when the body is not JSON", async () => {
+    const req = new NextRequest("http://localhost/api/v1/quotes/create", {
+      method: "POST",
+      body: "not-json",
+      headers: {
+        "content-type": "application/json",
+        authorization: `Bearer ${AGENT_KEY}`,
+      },
+    });
+    const res = await POST(req);
+    expect(res.status).toBe(400);
+    expect(createQuoteMock).not.toHaveBeenCalled();
+  });
+
+  it("returns 400 when customer is missing", async () => {
+    const res = await POST(makeReq({ ...baseBody, customer: "" }));
+    expect(res.status).toBe(400);
+    expect(createQuoteMock).not.toHaveBeenCalled();
+  });
+
+  it("returns 400 when items is empty", async () => {
+    const res = await POST(makeReq({ ...baseBody, items: [] }));
+    expect(res.status).toBe(400);
+    expect(createQuoteMock).not.toHaveBeenCalled();
+  });
+
+  it("returns 500 on a generic service error", async () => {
+    createQuoteMock.mockRejectedValueOnce(new Error("boom"));
+    const res = await POST(makeReq(baseBody));
+    expect(res.status).toBe(500);
+    const body = await res.json();
+    expect(body.error).toMatch(/boom/);
+  });
+});
diff --git a/src/lib/server/quotes-service.ts b/src/lib/server/quotes-service.ts
index 92b76b1..9103890 100644
--- a/src/lib/server/quotes-service.ts
+++ b/src/lib/server/quotes-service.ts
@@ -5,7 +5,7 @@ import {
   PLACEHOLDER_CUSTOMER_IDS,
   PLACEHOLDER_CUSTOMER_NAMES,
 } from "@/lib/placeholder-customers";
-import type { Quote, QuoteItem, Customer, Company } from "@/lib/types";
+import type { Quote, QuoteItem, Customer, Company, QuoteStatus } from "@/lib/types";
 
 /**
  * Server-side quote pipeline used by the MCP layer (n8n) and internal API routes.
@@ -2583,9 +2583,51 @@ export interface CreateQuoteInput {
   items: CreateQuoteInputItem[];
   /** Optional override — defaults to validity_days=30. */
   validity_days?: number;
+  /** Optional operator-supplied quote number (e.g. for re-quoting the
+   *  same customer under a stable reference). If omitted, the server
+   *  generates a fresh number from the atomic counter. Collisions with
+   *  an existing `quotes.quote_number` throw `QuoteNumberExistsError`
+   *  (caught at the REST layer → 409). */
+  quote_number?: string;
+  /** Customer-side reference (their RFQ number, PO reference, etc.).
+   *  Persists to `quotes.rfq_number`. */
+  rfq_number?: string;
+  /** Operator-facing free-text note rendered on the customer PDF
+   *  (distinct from the `notes` audit-log field). Persists to
+   *  `quotes.quote_notes`. */
+  quote_notes?: string;
+  /** Notes string (the audit-log field). Most callers should leave this
+   *  empty on create — the rejection pipeline writes here. Walk-in
+   *  creation accepts it for completeness. */
+  notes?: string;
+  /** Optional status override — defaults to "new". The full QuoteStatus
+   *  union is accepted; callers that want a stricter surface (e.g. the
+   *  REST route) validate the subset they expose. */
+  status?: QuoteStatus;
   is_no_quote?: boolean;
 }
 
+/**
+ * Thrown by `createQuote` when the operator-supplied `quote_number`
+ * collides with an existing quote. Maps to HTTP 409 at the REST layer
+ * (`/api/v1/quotes/create`). The `existingId` field carries the
+ * colliding row's PB id so the client can deep-link to it.
+ *
+ * Mirrors `OrderNumberCollisionError` (orders-service.ts).
+ */
+export class QuoteNumberExistsError extends Error {
+  readonly existingId: string;
+  readonly attemptedNumber: string;
+  constructor(existingId: string, attemptedNumber: string) {
+    super(
+      `Quote number "${attemptedNumber}" is already in use by another quote.`,
+    );
+    this.name = "QuoteNumberExistsError";
+    this.existingId = existingId;
+    this.attemptedNumber = attemptedNumber;
+  }
+}
+
 export interface CreateQuoteResult {
   quote: Quote;
   customer: Customer;
@@ -2646,24 +2688,58 @@ export async function createQuote(
     );
   }
 
-  // ── 3. Generate a quote number.
-  const quoteNumber = await generateQuoteNumberServer();
+  // ── 3. Resolve quote number. The operator may supply one (e.g. for a
+  // re-quote with a stable customer-side reference); otherwise we
+  // generate a fresh one from the atomic counter.
+  const operatorSuppliedNumber =
+    typeof input.quote_number === "string" && input.quote_number.trim()
+      ? input.quote_number.trim()
+      : null;
+  const quoteNumber = operatorSuppliedNumber ?? (await generateQuoteNumberServer());
 
-  // ── 4. Create the quote row.
-  const quote = await pb.collection(QUOTES_COLLECTION).create({
-    quote_number: quoteNumber,
-    customer: customer.id,
-    company: company?.id || null,
-    description: input.description || "",
-    status: "new",
-    notes: "",
-    validity_days: input.validity_days ?? QUOTE_VALID_DAYS,
-    company_letterhead: input.letterhead || "CNL",
-    has_attachments: false,
-    email_subject: input.description || "",
-    email_body: "",
-    is_no_quote: input.is_no_quote,
-  });
+  // ── 4. Create the quote row. PB enforces a unique index on
+  // `quotes.quote_number`; the try/catch below maps the DB-level
+  // UNIQUE violation back to the typed `QuoteNumberExistsError` so the
+  // REST layer can respond 409 with the colliding row's id.
+  // The let + try/catch shape means the type must be explicit; we
+  // mirror the inference the const-form would have produced (the
+  // generic RecordModel cast as `Quote` at the return point below).
+  let quote: Record<string, unknown> & { id: string };
+  try {
+    quote = await pb.collection(QUOTES_COLLECTION).create({
+      quote_number: quoteNumber,
+      customer: customer.id,
+      company: company?.id || null,
+      description: input.description || "",
+      status: input.status ?? "new",
+      notes: input.notes ?? "",
+      rfq_number: input.rfq_number ?? "",
+      quote_notes: input.quote_notes ?? "",
+      validity_days: input.validity_days ?? QUOTE_VALID_DAYS,
+      company_letterhead: input.letterhead || "CNL",
+      has_attachments: false,
+      email_subject: input.description || "",
+      email_body: "",
+      is_no_quote: input.is_no_quote,
+    });
+  } catch (err) {
+    // Race-safe: even when the operator didn't supply a number, the
+    // generated one could theoretically collide if the counter
+    // implementation changes. Catch the unique-constraint violation,
+    // re-query for the existing row's id, and re-throw typed.
+    if (err && /UNIQUE constraint failed/i.test(String(err))) {
+      const escaped = quoteNumber.replace(/"/g, '\\"');
+      const conflict = await pb
+        .collection(QUOTES_COLLECTION)
+        .getList<{ id: string }>(1, 1, {
+          filter: `quote_number = "${escaped}"`,
+        });
+      if (conflict.items[0]) {
+        throw new QuoteNumberExistsError(conflict.items[0].id, quoteNumber);
+      }
+    }
+    throw err;
+  }
 
   // ── 5. Create the line items via the shared service layer so the
   // F.1 auto-derive + F.2 whitelist apply unchanged.
@@ -2687,7 +2763,7 @@ export async function createQuote(
   }
 
   return {
-    quote: quote as Quote,
+    quote: quote as unknown as Quote,
     customer,
     company: company as Customer | null,
     items: createdItems,