frontend/src/pages/LocationMapManager.jsx

@@ -178,21 +178,23 @@ export default function LocationMapManager() {
 
       await markBought(activeHousehold.id, locationId, item.item_name, quantity, true);
 
+      let nextBuyModalItems = buyModalItems;
       if (quantity >= item.quantity) {
+        nextBuyModalItems = buyModalItems.filter((candidate) => candidate.id !== item.id);
         updateMapItems((currentItems) => currentItems.filter((candidate) => candidate.id !== item.id));
-        setBuyModalItem(getNextMapBuyItem(buyModalItems, resolvedIndex, item.id));
       } else {
         const response = await getItemByName(activeHousehold.id, locationId, item.item_name);
         const updatedItem = response.data || {
           ...item,
           quantity: Math.max(1, Number(item.quantity || 1) - Number(quantity || 1)),
         };
+        nextBuyModalItems = buyModalItems.map((candidate) => (candidate.id === item.id ? updatedItem : candidate));
 
         updateMapItems((currentItems) =>
           currentItems.map((candidate) => (candidate.id === item.id ? updatedItem : candidate))
         );
-        setBuyModalItem(updatedItem);
       }
+      setBuyModalItem(getNextMapBuyItem(nextBuyModalItems, resolvedIndex, item.id));
 
       toast.success("Marked item bought", `Marked item ${item.item_name} as bought`);
     } catch (error) {

frontend/tests/location-map-manager.spec.ts

@@ -2352,6 +2352,99 @@ test("viewer can buy selected zone items from the map", async ({ page }) => {
   await expect(page.getByText("No items assigned to this zone yet.")).toBeVisible();
 });
 
+test("viewer advances map buy modal after partial quantity buys", async ({ page }) => {
+  await mockMapShell(page);
+
+  const partialItems = [
+    {
+      id: 4301,
+      item_name: "flour",
+      quantity: 3,
+      bought: false,
+      zone_id: 501,
+      zone: "Bakery",
+      added_by_users: ["map-user"],
+    },
+    {
+      id: 4302,
+      item_name: "yeast",
+      quantity: 1,
+      bought: false,
+      zone_id: 501,
+      zone: "Bakery",
+      added_by_users: ["map-user"],
+    },
+  ];
+  const updatedFlour = { ...partialItems[0], quantity: 2 };
+  const mapState = {
+    ...publishedMapState([
+      {
+        id: 1534,
+        location_map_id: 901,
+        zone_id: 501,
+        zone_name: "Bakery",
+        type: "zone",
+        label: "Bakery",
+        x: 40,
+        y: 40,
+        width: 260,
+        height: 160,
+        rotation: 0,
+        locked: false,
+        visible: true,
+        sort_order: 1,
+      },
+    ], true),
+    items: partialItems,
+  };
+  const boughtPayloads: Array<Record<string, unknown>> = [];
+
+  await page.route("**/households/1/locations/10/map", async (route) => {
+    await route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify(mapState),
+    });
+  });
+
+  await page.route("**/households/1/locations/10/list/item**", async (route) => {
+    if (route.request().method() === "GET") {
+      await route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify(updatedFlour),
+      });
+      return;
+    }
+
+    boughtPayloads.push(await route.request().postDataJSON());
+    await route.fulfill({
+      status: 200,
+      contentType: "application/json",
+      body: JSON.stringify({ success: true }),
+    });
+  });
+
+  await page.goto("/stores/100/locations/10/map");
+  await page.locator('[data-object-key="1534"]').locator("rect").first().click();
+  await page.getByRole("button", { name: "Mark flour bought" }).click();
+  await expect(page.locator(".confirm-buy-item-name")).toHaveText("flour");
+
+  await page.locator(".confirm-buy-counter-btn").first().click();
+  await page.locator(".confirm-buy-counter-btn").first().click();
+  await expect(page.locator(".confirm-buy-counter-display")).toHaveValue("1");
+  await page.getByRole("button", { name: "Mark as Bought" }).click();
+
+  await expect.poll(() => boughtPayloads.length).toBe(1);
+  expect(boughtPayloads[0]).toMatchObject({
+    item_name: "flour",
+    bought: true,
+    quantity_bought: 1,
+  });
+  await expect(page.locator(".confirm-buy-item-name")).toHaveText("yeast");
+  await expect(page.getByRole("button", { name: "Mark flour bought" }).locator("small")).toHaveText("x2");
+});
+
 test("viewer shows completed zone items without rebuy actions", async ({ page }) => {
   await mockMapShell(page);