feat(collection-pool): sequential bulk-assign PATCH

src/app/(app)/collection-pool/page.tsx

@@ -355,10 +355,57 @@ export default function CollectionPoolPage() {
   const [bulkBusy, setBulkBusy] = useState(false);
 
   const handleBulkAssignSubmit = useCallback(
-    async (_payload: AssignDriverSubmitPayload) => {
-      // Full implementation in Task 9.
+    async (payload: AssignDriverSubmitPayload) => {
+      if (!bulkAssignDialog) return;
+      const { driverId, date } = payload;
+      const { rowIds, supplierName } = bulkAssignDialog;
+
+      setBulkBusy(true);
+      try {
+        const pb = getPocketBase();
+        let successCount = 0;
+        let firstError: string | null = null;
+
+        // Sequential, not parallel: any failure leaves earlier
+        // successes committed (matches the single-row PATCH semantics).
+        for (const id of rowIds) {
+          try {
+            await pb.collection("order_items").update(id, {
+              item_status: "assigned",
+              drv_id: driverId,
+              drv_status: "assigned",
+              assigned_at: `${date}T00:00:00.000Z`,
+            } as Partial<OrderItem>);
+            successCount++;
+          } catch (err) {
+            if (!firstError) {
+              firstError = err instanceof Error ? err.message : String(err);
+            }
+          }
+        }
+
+        // Clear selections for this supplier on success (partial or full).
+        setSelectedIds((prev) => {
+          const next = new Set(prev);
+          for (const id of rowIds) next.delete(id);
+          return next;
+        });
+        closeBulkAssign();
+
+        if (firstError) {
+          toast.error(
+            `Assigned ${successCount} of ${rowIds.length} stops at ${supplierName || "supplier"}. First error: ${firstError}`,
+          );
+        } else {
+          toast.success(`Assigned ${successCount} stops at ${supplierName || "supplier"}.`);
+        }
+
+        await load();
+      } finally {
+        setBulkBusy(false);
+      }
     },
-    [],
+    [bulkAssignDialog, closeBulkAssign, load],
   );
 
   const handleToggleReady = useCallback(