Auto-seed new current lot on lot switch to avoid allocation loop

order-import.php

@@ -994,7 +994,7 @@ function get_current_lot_balance_for_update(PDO $pdo, int $productId): array
     ];
 }
 
-function switch_current_lot(PDO $pdo, int $productId, int $oldCurrentLotId): int
+function switch_current_lot(PDO $pdo, int $productId, int $oldCurrentLotId, int $storageLocationId): int
 {
     $closeStmt = $pdo->prepare(
         "UPDATE public.stock_lot
@@ -1030,6 +1030,23 @@ function switch_current_lot(PDO $pdo, int $productId, int $oldCurrentLotId): int
         ':auto_lot_number' => 'AUTO-' . $productId . '-' . (int) $newCurrentLotId,
     ]);
 
+    $balStmt = $pdo->prepare('SELECT qty_net FROM public.v_stock_lot_balance WHERE stock_lot_id = :lot_id');
+    $balStmt->execute([':lot_id' => (int) $newCurrentLotId]);
+    $newCurrentQty = $balStmt->fetchColumn();
+    $newCurrentQty = $newCurrentQty === false ? 0.0 : (float) $newCurrentQty;
+
+    // Auto-seed newly promoted current lot so allocation can continue without manual stock-in.
+    if ($newCurrentQty <= 0.0000001) {
+        insert_stock_move_in(
+            $pdo,
+            $productId,
+            (int) $newCurrentLotId,
+            200.0,
+            $storageLocationId,
+            "auto-seed-current-lot:product={$productId}:lot=" . (int) $newCurrentLotId
+        );
+    }
+
     $createOpenStmt = $pdo->prepare(
         "INSERT INTO public.stock_lot (product_id, lot_number, status, created_at, updated_at)
          VALUES (:product_id, NULL, 'open', NOW(), NOW())"
@@ -1152,6 +1169,24 @@ function reverse_existing_allocations_for_order(PDO $pdo, int $orderId, int $fal
     ];
 }
 
+function has_available_stock_for_product(PDO $pdo, int $productId, float $epsilon = 0.0000001): bool
+{
+    $stmt = $pdo->prepare(
+        "SELECT 1
+         FROM public.stock_lot sl
+         JOIN public.v_stock_lot_balance v ON v.stock_lot_id = sl.id
+         WHERE sl.product_id = :product_id
+           AND v.qty_net > :epsilon
+         LIMIT 1"
+    );
+    $stmt->execute([
+        ':product_id' => $productId,
+        ':epsilon' => $epsilon,
+    ]);
+
+    return $stmt->fetchColumn() !== false;
+}
+
 function allocate_components_for_line(
     PDO $pdo,
     int $orderId,
@@ -1169,6 +1204,9 @@ function allocate_components_for_line(
         ];
     }
 
+    $savepoint = 'sp_alloc_line_' . $lineId;
+    $pdo->exec("SAVEPOINT {$savepoint}");
+
     $allocationInsert = $pdo->prepare(
         "INSERT INTO public.sales_order_line_lot_allocation (
             sales_order_line_id, product_id, lot_id, qty, allocation_status, stock_move_id, created_at, updated_at
@@ -1188,7 +1226,13 @@ function allocate_components_for_line(
         while ($remaining > 0.0000001) {
             $guard++;
             if ($guard > 100) {
-                throw new RuntimeException("Inventory allocation loop exceeded guard for product {$productId}");
+                $pdo->exec("ROLLBACK TO SAVEPOINT {$savepoint}");
+                $pdo->exec("RELEASE SAVEPOINT {$savepoint}");
+                return [
+                    'allocated' => false,
+                    'reason' => "loop_guard_exceeded:product={$productId}",
+                    'allocations' => [],
+                ];
             }
 
             $current = get_current_lot_balance_for_update($pdo, $productId);
@@ -1196,7 +1240,7 @@ function allocate_components_for_line(
             $available = (float) $current['qty_net'];
 
             if ($available <= 0.0000001) {
-                switch_current_lot($pdo, $productId, $lotId);
+                switch_current_lot($pdo, $productId, $lotId, (int) $locations['storage']);
                 continue;
             }
 
@@ -1231,6 +1275,8 @@ function allocate_components_for_line(
         }
     }
 
+    $pdo->exec("RELEASE SAVEPOINT {$savepoint}");
+
     return [
         'allocated' => true,
         'reason' => '',