diff --git a/src/lib/server/orders-service.test.ts b/src/lib/server/orders-service.test.ts
index 753a09e..5c51869 100644
--- a/src/lib/server/orders-service.test.ts
+++ b/src/lib/server/orders-service.test.ts
@@ -3056,3 +3056,90 @@ describe("createOrder delivery-note auto-detection", () => {
     expect(suggestDeliveryNoteForOrder).toHaveBeenCalledWith(created.order.id);
   });
 });
+
+describe("createOrderItemForOrder (mid-flight add)", () => {
+  // Task 2 of the non-invoiceable-order-extras plan — the pending
+  // gate that previously 409'd when siblings were po_generated is
+  // removed because adding a new row is independent of any in-flight
+  // PO's pricing/supplier reference. Three tests below cover the
+  // contract: (a) the gate is gone, (b) the new flag is authoritative
+  // for selling_price, (c) omission leaves the row billable.
+
+  it("adds a line to an order whose siblings are po_generated (was previously 409 order_locked)", async () => {
+    const { createOrderItemForOrder } = await import("./orders-service");
+    await pbMock.collection("orders").create({
+      id: "o-1",
+      order_number: "ORD-1",
+      // Customer + company required by createOrder's lead row — skip
+      // for this targeted test by using a minimal stub.
+    });
+    await pbMock.collection("order_items").create({
+      id: "oi-existing",
+      order: "o-1",
+      description: "Bolt",
+      quantity: 50,
+      item_status: "po_generated",
+    });
+
+    const result = await createOrderItemForOrder("o-1", {
+      description: "Washer",
+      quantity: 50,
+      cost_price: 5,
+    });
+
+    expect(result.failed).toEqual([]);
+    expect(result.created.length).toBe(1);
+    expect(result.created[0].description).toBe("Washer");
+    expect(result.orderLocked).toBe(false);
+  });
+
+  it("exclude_from_invoice forces selling_price to 0 even when caller passes a non-zero price", async () => {
+    const { createOrderItemForOrder } = await import("./orders-service");
+    await pbMock.collection("orders").create({
+      id: "o-1",
+      order_number: "ORD-1",
+    });
+
+    const result = await createOrderItemForOrder("o-1", {
+      description: "Nut",
+      quantity: 50,
+      cost_price: 10,
+      markup: 50, // would compute selling_price = 15 without the flag
+      selling_price: 15, // would persist 15 without the flag
+      exclude_from_invoice: true,
+    });
+
+    expect(result.created[0].selling_price).toBe(0);
+    expect(result.created[0].markup).toBe(50); // markup stays as-is
+
+    // The flag itself persists on the secondary update — separate
+    // assertion because the `created[]` return shape doesn't include
+    // it.
+    const stored = (store["order_items"] as Map<string, Record<string, unknown>>).get(
+      result.created[0].id,
+    );
+    expect(stored?.exclude_from_invoice).toBe(true);
+    expect(stored?.selling_price).toBe(0);
+  });
+
+  it("omitting exclude_from_invoice preserves the existing markup-based selling_price calculation", async () => {
+    const { createOrderItemForOrder } = await import("./orders-service");
+    await pbMock.collection("orders").create({
+      id: "o-1",
+      order_number: "ORD-1",
+    });
+
+    const result = await createOrderItemForOrder("o-1", {
+      description: "Bolt",
+      quantity: 50,
+      cost_price: 10,
+      markup: 25,
+    });
+
+    expect(result.created[0].selling_price).toBe(12.5); // 10 * 1.25
+    const stored = (store["order_items"] as Map<string, Record<string, unknown>>).get(
+      result.created[0].id,
+    );
+    expect(stored?.exclude_from_invoice).toBeFalsy();
+  });
+});
diff --git a/src/lib/server/orders-service.ts b/src/lib/server/orders-service.ts
index 6cd6b76..7724e89 100644
--- a/src/lib/server/orders-service.ts
+++ b/src/lib/server/orders-service.ts
@@ -3874,24 +3874,51 @@ export interface CreateOrderItemForOrderDraft {
   unit?: string;
   supplier?: string;
   notes?: string;
+  /**
+   * Mark this line as supplier-side only — gets a PO, a driver, and
+   * collection like any other line, but never appears on a customer
+   * invoice or delivery note. Forces `selling_price` to 0
+   * regardless of what the caller passes (the flag is authoritative,
+   * price is not consulted downstream).
+   *
+   * See docs/superpowers/specs/2026-08-30-non-invoiceable-order-extras-design.md
+   * for the supplier-component-split use case that motivates it.
+   */
+  exclude_from_invoice?: boolean;
 }
 
 /**
  * Add a new line item to an existing order.
  *
- * **Strict `pending` gate**: refuses with 409 (`order_locked`) if
- * any line item on the order is past `item_status === "pending"`.
- * Adding a line to an order with a PO in flight would orphan the
- * PO's pricing/supplier reference. Operator must split the order
- * (use `orders.split`) or finish the existing PO first.
+ * **No `pending` gate** (removed 2026-08-30). The original gate
+ * refused with 409 if any sibling line was past `pending`, on the
+ * theory that adding a row alongside an in-flight PO would orphan
+ * the PO's pricing/supplier reference. That was a wrong model of
+ * what adding a row does — the new row is independent: it gets its
+ * own PO when the operator processes it, and never touches the
+ * existing PO's supplier / cost / quantity. The real reason to
+ * refuse used to be that operators had no other way to add extras,
+ * so they didn't notice the gate until they hit it; the non-
+ * invoiceable extras feature added the `Add item` affordance on the
+ * process page (see Task 3), so the use case is now legitimate and
+ * frequent.
+ *
+ * There is a separate, unrelated `nonPending` gate in `setOrderQuote`
+ * (line ~3744) that prevents changing a quote link after the order
+ * has been processed. That gate stays — different invariant.
  *
  * Mirrors what `createOrder` does for new orders: calls
  * `createOrderItems` for the primary row, then patches the
- * secondary fields (sku/unit/supplier/notes) on success.
+ * secondary fields (sku/unit/supplier/notes/exclude_from_invoice)
+ * on success.
  *
  * The `selling_price` defaults to `cost_price * (1 + markup/100)`
  * via `deriveSellingPriceIfOmitted` when omitted. Markup defaults
- * to 0 when both `selling_price` and `markup` are absent.
+ * to 0 when both `selling_price` and `markup` are absent. When
+ * `exclude_from_invoice` is true, `selling_price` is forced to 0
+ * regardless of the caller input — the flag is the source of truth,
+ * and downstream invoice / delivery-note code keys on it, not on
+ * the price column.
  *
  * Returns `{ created, failed }` like `createOrderItems`. Per-row
  * failures never abort the whole call.
@@ -3924,37 +3951,19 @@ export async function createOrderItemForOrder(
     throw err;
   }
 
-  // Strict pending gate: refuse if any line item is past `pending`.
-  // Statuses here mirror `orders.split` — only `pending` items are
-  // eligible for mutation (adding a line). Anything else would
-  // orphan an in-flight PO / driver assignment.
-  const nonPending = await pb
-    .collection(getOrderItemsCollectionName())
-    .getFullList<{ id: string; item_status: string }>({
-      filter: `order = "${orderId}" && item_status != "pending"`,
-      fields: "id,item_status",
-      batch: 1000,
-    });
-
-  if (nonPending.length > 0) {
-    const err = new Error(
-      `Cannot add items to order — ${nonPending.length} line item(s) are past 'pending' status. ` +
-      `Use orders.split to create a continuation order, or finish the existing PO first.`,
-    );
-    (err as Error & { status?: number }).status = 409;
-    (err as Error & { data?: unknown }).data = {
-      code: "order_locked",
-      offendingItemIds: nonPending.map((i) => i.id),
-      offendingStatuses: [...new Set(nonPending.map((i) => i.item_status))],
-    };
-    throw err;
-  }
-
-  // Compute selling_price if omitted.
+  // Compute selling_price. When the line is excluded from invoicing
+  // the flag wins — a non-zero price from the caller is overridden
+  // to 0 so the row's invoice/collection status stays consistent
+  // with what the UI said (the flag itself is also persisted in the
+  // secondary-field patch below).
   const costPrice = draft.cost_price ?? 0;
   const markup = draft.markup ?? 0;
-  let sellingPrice = draft.selling_price;
-  if (sellingPrice == null) {
+  let sellingPrice: number;
+  if (draft.exclude_from_invoice) {
+    sellingPrice = 0;
+  } else if (draft.selling_price != null) {
+    sellingPrice = draft.selling_price;
+  } else {
     sellingPrice = Number((costPrice * (1 + markup / 100)).toFixed(2));
   }
 
@@ -3969,7 +3978,8 @@ export async function createOrderItemForOrder(
   ]);
 
   // Patch secondary fields on the newly created row (sku / unit /
-  // supplier / notes) — same pattern as `createOrder` uses.
+  // supplier / notes / exclude_from_invoice) — same pattern as
+  // `createOrder` uses.
   if (result.created.length > 0) {
     const newId = result.created[0].id;
     const secondary: Record<string, unknown> = {};
@@ -3977,6 +3987,7 @@ export async function createOrderItemForOrder(
     if (draft.unit) secondary.unit = draft.unit;
     if (draft.supplier) secondary.supplier = draft.supplier;
     if (draft.notes) secondary.notes = draft.notes;
+    if (draft.exclude_from_invoice) secondary.exclude_from_invoice = true;
     if (Object.keys(secondary).length > 0) {
       await pb.collection(getOrderItemsCollectionName()).update(newId, secondary);
     }
@@ -3986,6 +3997,9 @@ export async function createOrderItemForOrder(
     orderId,
     created: result.created,
     failed: result.failed.map((f) => ({ error: f.error })),
+    // Kept for API compatibility — the field is now always `false`
+    // because there is no longer a pending gate. Pre-existing callers
+    // reading this shape continue to compile and read a constant.
     orderLocked: false,
   };
 }