diff --git a/app/assets/js/custom.js b/app/assets/js/custom.js
index 3d7aea4..a86a945 100644
--- a/app/assets/js/custom.js
+++ b/app/assets/js/custom.js
@@ -581,9 +581,19 @@ function load_formula_options(select_id, document_type, selected_id, onLoaded) {
   });
 }
 
+// Line tax rate; derived from tax_amount / total_price when only the amount was stored
+function line_tax_rate(item) {
+  var rate   = parseFloat(item.tax_rate)    || 0;
+  var amount = parseFloat(item.tax_amount)  || 0;
+  var total  = parseFloat(item.total_price) || 0;
+  if (rate === 0 && amount > 0 && total > 0) rate = round_dp(amount / total * 100, 2);
+  return rate;
+}
+
+// Returns the request promise so callers can await the options before selecting a value
 function load_departments(select_id, selected_id) {
   var ctx = document.getElementById('session-context');
-  ajax_request({
+  return ajax_request({
     url:       server_url + 'accounting/api/engine/department.php',
     action:    'get',
     queueLock: false,
diff --git a/app/assets/utils/classes/OrderManager.php b/app/assets/utils/classes/OrderManager.php
index 37df2ec..2fdfeb5 100644
--- a/app/assets/utils/classes/OrderManager.php
+++ b/app/assets/utils/classes/OrderManager.php
@@ -260,7 +260,10 @@ class OrderManager {
     {
         $sth = $this->pdo->prepare(
             "SELECT o.*,
-                    COALESCE(c.contact_name, '') AS contact_name
+                    COALESCE(c.contact_name, '') AS contact_name,
+                    (SELECT COUNT(*) FROM td_order_item i
+                     WHERE i.company_id = o.company_id
+                       AND i.order_id   = o.id) AS item_count
              FROM td_order o
              LEFT JOIN md_contact c
                  ON  c.company_id = o.company_id
@@ -493,7 +496,7 @@ class OrderManager {
 
             // Fetch existing row to check status and load log
             $sth = $this->pdo->prepare(
-                "SELECT status, `log` FROM td_order
+                "SELECT status, department_id, `log` FROM td_order
                  WHERE company_id = :company_id AND id = :id"
             );
             $sth->execute([':company_id' => $this->company_id, ':id' => $id]);
@@ -502,6 +505,11 @@ class OrderManager {
             if (!$row) {
                 throw new Exception("Order not found.");
             }
+
+            // Pages without a department field (Revenue SO) must not wipe the stored one
+            $department_id = array_key_exists('department_id', $data)
+                ? (int)$data['department_id']
+                : (int)$row['department_id'];
             $cur_status = (int)$row['status'];
             if ($cur_status !== 0 && $cur_status !== -2) {
                 throw new Exception("Only draft or pending orders can be edited.");
@@ -541,7 +549,7 @@ class OrderManager {
                  WHERE id = :id AND company_id = :company_id"
             )->execute([
                 ':contact_id'    => (int)($data['contact_id']    ?? 0),
-                ':department_id' => (int)($data['department_id'] ?? 0),
+                ':department_id' => $department_id,
                 ':order_date'    => $data['order_date'] ?? date('Y-m-d'),
                 ':subtotal'        => $subtotal,
                 ':discount'        => $discount,
diff --git a/app/assets/utils/classes/PurchaseOrderManager.php b/app/assets/utils/classes/PurchaseOrderManager.php
index f4d4918..43da110 100644
--- a/app/assets/utils/classes/PurchaseOrderManager.php
+++ b/app/assets/utils/classes/PurchaseOrderManager.php
@@ -194,7 +194,10 @@ class PurchaseOrderManager {
     {
         $sth = $this->pdo->prepare(
             "SELECT p.*,
-                    COALESCE(c.contact_name, '') AS contact_name
+                    COALESCE(c.contact_name, '') AS contact_name,
+                    (SELECT COUNT(*) FROM td_purchase_order_item i
+                     WHERE i.company_id = p.company_id
+                       AND i.order_id   = p.id) AS item_count
              FROM td_purchase_order p
              LEFT JOIN md_contact c
                  ON  c.company_id = p.company_id
diff --git a/app/assets/utils/classes/PurchaseRequestManager.php b/app/assets/utils/classes/PurchaseRequestManager.php
index 597d407..13a0a30 100644
--- a/app/assets/utils/classes/PurchaseRequestManager.php
+++ b/app/assets/utils/classes/PurchaseRequestManager.php
@@ -94,7 +94,10 @@ class PurchaseRequestManager
                      WHERE p.company_id = r.company_id
                        AND p.source     = 'purchase_request'
                        AND p.source_id  = r.id
-                       AND p.status    != -1) AS linked_po_count
+                       AND p.status    != -1) AS linked_po_count,
+                    (SELECT COUNT(*) FROM td_purchase_request_item i
+                     WHERE i.company_id = r.company_id
+                       AND i.request_id = r.id) AS item_count
              FROM td_purchase_request r
              LEFT JOIN md_contact c
                ON c.company_id = r.company_id AND c.id = r.contact_id
@@ -166,6 +169,12 @@ class PurchaseRequestManager
 
         if (empty($items)) throw new Exception('At least one item is required.');
 
+        $request_date  = (string)($data['request_date']  ?? '');
+        $required_date = (string)($data['required_date'] ?? '');
+        if ($request_date !== '' && $required_date !== '' && $required_date < $request_date) {
+            throw new Exception('Required date cannot be earlier than the request date.');
+        }
+
         [$subtotal, $tax, $grand] = $this->computeTotals($items, $discount, $shipping_fee);
 
         if ($id === 0) {
diff --git a/app/assets/utils/classes/QuotationManager.php b/app/assets/utils/classes/QuotationManager.php
index 7dd4690..58e7dd6 100644
--- a/app/assets/utils/classes/QuotationManager.php
+++ b/app/assets/utils/classes/QuotationManager.php
@@ -89,7 +89,10 @@ class QuotationManager
     public function getList(): array
     {
         $sth = $this->pdo->prepare(
-            "SELECT q.*, COALESCE(c.contact_name, '') AS contact_name
+            "SELECT q.*, COALESCE(c.contact_name, '') AS contact_name,
+                    (SELECT COUNT(*) FROM td_quotation_item i
+                     WHERE i.company_id   = q.company_id
+                       AND i.quotation_id = q.id) AS item_count
              FROM td_quotation q
              LEFT JOIN md_contact c
                ON c.id = q.contact_id AND c.company_id = q.company_id
@@ -173,6 +176,24 @@ class QuotationManager
         $items    = $data['items'] ?? [];
         $discount = (float)($data['discount'] ?? 0);
 
+        $quotation_date = (string)($data['quotation_date'] ?? '');
+        $valid_until    = (string)($data['valid_until']    ?? '');
+        if ((int)($data['contact_id'] ?? 0) <= 0) {
+            throw new Exception('Contact is required.');
+        }
+        if ($quotation_date === '') {
+            throw new Exception('Quotation date is required.');
+        }
+        if ($valid_until !== '' && $valid_until < $quotation_date) {
+            throw new Exception('Valid until cannot be earlier than the quotation date.');
+        }
+        if ((int)($data['department_id'] ?? 0) <= 0) {
+            throw new Exception('Department is required.');
+        }
+        if (empty($items)) {
+            throw new Exception('At least one line item is required.');
+        }
+
         [$subtotal, $tax, $grand] = $this->computeTotals($items, $discount);
 
         if ($id === 0) {
diff --git a/app/assets/utils/classes/ReturnManager.php b/app/assets/utils/classes/ReturnManager.php
index e68b98a..7d5029f 100644
--- a/app/assets/utils/classes/ReturnManager.php
+++ b/app/assets/utils/classes/ReturnManager.php
@@ -169,7 +169,10 @@ class ReturnManager {
         $sth = $this->pdo->prepare(
             "SELECT r.*,
                     COALESCE(c.contact_name, '') AS contact_name,
-                    o.order_number
+                    o.order_number,
+                    (SELECT COUNT(*) FROM td_return_item i
+                     WHERE i.company_id = r.company_id
+                       AND i.return_id  = r.id) AS item_count
              FROM td_return r
              LEFT JOIN md_contact c
                  ON  c.company_id = r.company_id
diff --git a/app/assets/utils/classes/SupplierReturnManager.php b/app/assets/utils/classes/SupplierReturnManager.php
index 5538fcc..0b809d8 100644
--- a/app/assets/utils/classes/SupplierReturnManager.php
+++ b/app/assets/utils/classes/SupplierReturnManager.php
@@ -154,7 +154,10 @@ class SupplierReturnManager {
         $sth = $this->pdo->prepare(
             "SELECT r.*,
                     COALESCE(c.contact_name, '') AS contact_name,
-                    p.po_number
+                    p.po_number,
+                    (SELECT COUNT(*) FROM td_supplier_return_item i
+                     WHERE i.company_id = r.company_id
+                       AND i.return_id  = r.id) AS item_count
              FROM td_supplier_return r
              LEFT JOIN md_contact c
                  ON  c.company_id = r.company_id
diff --git a/app/expense/api/engine/convert_purchase_request.php b/app/expense/api/engine/convert_purchase_request.php
index 8ba4d99..b225d69 100644
--- a/app/expense/api/engine/convert_purchase_request.php
+++ b/app/expense/api/engine/convert_purchase_request.php
@@ -15,10 +15,6 @@ if (!$request_id) {
     $answer['message'] = 'Purchase request ID is required.';
     exit(json_encode($answer));
 }
-if (!$contact_id) {
-    $answer['message'] = 'Supplier (contact_id) is required for the PO.';
-    exit(json_encode($answer));
-}
 
 $prm = new PurchaseRequestManager($pdo2, $company_id);
 
@@ -29,6 +25,15 @@ if (!$pr || (int)$pr['status'] !== 2) {
     exit(json_encode($answer));
 }
 
+// Default to the PR's preferred supplier
+if (!$contact_id) {
+    $contact_id = (int)($pr['contact_id'] ?? 0);
+}
+if (!$contact_id) {
+    $answer['message'] = 'Set a Preferred Supplier on this purchase request before converting it to a PO.';
+    exit(json_encode($answer));
+}
+
 $pr_items = $pr['items'];
 if (empty($pr_items)) {
     $answer['message'] = 'Purchase request has no items.';
@@ -92,6 +97,7 @@ foreach ($convert_items as $ci) {
         'unit_price'   => $unit_price,
         'total_price'  => $total_price,
         'tax_amount'   => $tax_amount,
+        'tax_rate'     => (float)($pi['tax_rate'] ?? 0),
         'received_qty' => 0,
         'stock_in_id'  => 0,
     ];
diff --git a/app/expense/manage_purchase_order.php b/app/expense/manage_purchase_order.php
index 86986ca..1e6d522 100644
--- a/app/expense/manage_purchase_order.php
+++ b/app/expense/manage_purchase_order.php
@@ -194,7 +194,7 @@
       <td><input type="number" class="form-control form-control-sm item_qty" value="${item.quantity || 1}" min="0.0001" step="any" oninput="recalc_totals()"></td>
       <td><input type="number" class="form-control form-control-sm item_price" value="${item.unit_price || item.price || 0}" min="0" step="any" oninput="recalc_totals()"></td>
       <td>
-        <input type="number" class="form-control form-control-sm item_tax_rate" value="${parseFloat(item.tax_rate || 0).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
+        <input type="number" class="form-control form-control-sm item_tax_rate" value="${line_tax_rate(item).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
         <input type="hidden" class="item_tax_amount" value="${item.tax_amount || 0}">
       </td>
       <td class="item_total text-end">${format_number((item.quantity || 1) * (item.unit_price || item.price || 0), 2)}</td>
@@ -371,8 +371,8 @@
     recalc_totals();
   });
 
-  $(function() {
-    load_departments('department_id');
+  $(async function() {
+    await Promise.resolve(load_departments('department_id')).catch(function() {});
     flatpickr('#po_date', { dateFormat: 'd/m/Y', allowInput: true });
     flatpickr('#expected_date', { dateFormat: 'd/m/Y', allowInput: true });
     if (po_id) {
diff --git a/app/expense/manage_purchase_request.php b/app/expense/manage_purchase_request.php
index 08f4db4..4d9a607 100644
--- a/app/expense/manage_purchase_request.php
+++ b/app/expense/manage_purchase_request.php
@@ -370,8 +370,9 @@
     recalc_totals();
   });
 
-  $(function() {
-    load_departments('department_id');
+  $(async function() {
+    // Options must exist before retrieve_request() selects the saved department
+    await Promise.resolve(load_departments('department_id')).catch(function() {});
     flatpickr('#request_date', { dateFormat: 'd/m/Y', allowInput: true });
     flatpickr('#required_date', { dateFormat: 'd/m/Y', allowInput: true });
     if (request_id) {
diff --git a/app/expense/purchase_request.php b/app/expense/purchase_request.php
index 2b18169..f5a3c39 100644
--- a/app/expense/purchase_request.php
+++ b/app/expense/purchase_request.php
@@ -180,7 +180,7 @@
       return;
     }
     $.each(rows, function(i, r) {
-      var items = typeof r.items === 'string' ? JSON.parse(r.items || '[]') : (r.items || []);
+      var item_count = parseInt(r.item_count) || 0;
       var po_link = r.po_id > 0
         ? `<a href="<?php echo $server_url?>expense/manage_purchase_order.php?id=${r.po_id}">${escape_html(r.po_number || ('PO #' + r.po_id))}</a>`
         : '<span class="text-muted">—</span>';
@@ -190,7 +190,7 @@
         <td class="py-3">${r.required_date ? format_date(r.required_date) : '<span class="text-muted">—</span>'}</td>
         <td class="py-3">${escape_html(r.contact_name || '—')}</td>
         <td class="py-3">${get_dept_label(r.department_id)}</td>
-        <td class="py-3">${items.length} item${items.length !== 1 ? 's' : ''}</td>
+        <td class="py-3">${item_count} item${item_count !== 1 ? 's' : ''}</td>
         <td class="py-3 fw-semibold">${format_number(r.grand_total, 2)}</td>
         <td class="py-3">${status_badge[String(r.status)] || r.status}</td>
         <td class="py-3">${po_link}</td>
diff --git a/app/include_header.php b/app/include_header.php
index 46ca22e..65ed825 100644
--- a/app/include_header.php
+++ b/app/include_header.php
@@ -85,7 +85,7 @@ header('Referrer-Policy: strict-origin-when-cross-origin');
   <link rel="stylesheet" href="<?php echo $server_url?>assets/css/main.css">
   <script type="module" src="<?php echo $server_url?>assets/js/main.js"></script>
   <link rel="stylesheet" href="<?php echo $server_url?>assets/css/custom.css">
-  <script src="<?php echo $server_url?>assets/js/custom.js"></script>
+  <script src="<?php echo $server_url?>assets/js/custom.js?v=<?php echo @filemtime(__DIR__ . '/assets/js/custom.js'); ?>"></script>
   <script src="<?php echo $server_url?>assets/js/batch_overlay.js"></script>
 
   <script src="https://cdnjs.cloudflare.com/ajax/libs/html5-qrcode/2.3.8/html5-qrcode.min.js"
diff --git a/app/order/manage_order.php b/app/order/manage_order.php
index f2121e3..a780942 100644
--- a/app/order/manage_order.php
+++ b/app/order/manage_order.php
@@ -341,7 +341,7 @@
       </td>
       <td>
         <input type="number" class="form-control form-control-sm item_tax_rate"
-          value="${parseFloat(item.tax_rate || 0).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
+          value="${line_tax_rate(item).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
         <input type="hidden" class="item_tax_amount" value="${item.tax_amount || 0}">
       </td>
       <td class="item_total text-end">${format_number((item.quantity || 1) * (item.unit_price || item.price || 0), 2)}</td>
@@ -712,7 +712,7 @@
   // ── Boot ─────────────────────────────────────────────────────────────────
   $(async function() {
     try {
-      load_departments('department_id');
+      await Promise.resolve(load_departments('department_id')).catch(function() {});
       await retrieve_warehouses();
 
       if (order_id) {
diff --git a/app/order/order.php b/app/order/order.php
index a230d40..58f0b81 100644
--- a/app/order/order.php
+++ b/app/order/order.php
@@ -241,8 +241,7 @@
     var body      = '';
 
     $.each(page_data, function(i, o) {
-      var items      = JSON.parse(o.items || '[]');
-      var item_count = items.length;
+      var item_count = parseInt(o.item_count) || 0;
       var can_edit   = parseInt(o.status) === 0;
       var can_cancel = parseInt(o.status) >= 0 && parseInt(o.status) <= 1;
 
diff --git a/app/order/return.php b/app/order/return.php
index ff4ab5a..29ab4ba 100644
--- a/app/order/return.php
+++ b/app/order/return.php
@@ -158,7 +158,7 @@
     var body      = '';
 
     $.each(page_data, function(i, r) {
-      var items      = JSON.parse(r.items || '[]');
+      var item_count = parseInt(r.item_count) || 0;
       var can_cancel = parseInt(r.status) >= 0 && parseInt(r.status) <= 1;
 
       body += `<tr>
@@ -167,7 +167,7 @@
         <td class="py-3">${r.contact_name || '<span class="text-muted">—</span>'}</td>
         <td class="py-3">${get_dept_label(r.department_id)}</td>
         <td class="py-3">${format_date(r.return_date)}</td>
-        <td class="py-3">${items.length} item${items.length !== 1 ? 's' : ''}</td>
+        <td class="py-3">${item_count} item${item_count !== 1 ? 's' : ''}</td>
         <td class="py-3 fw-semibold">${format_number(r.refund_amount, 2)}</td>
         <td class="py-3">${return_status_badge(r.status)}</td>
         <td class="py-3">${receipt_status_badge(r.receipt_status)}</td>
diff --git a/app/po/manage_po.php b/app/po/manage_po.php
index a04c39f..f241786 100644
--- a/app/po/manage_po.php
+++ b/app/po/manage_po.php
@@ -326,7 +326,7 @@
       </td>
       <td>
         <input type="number" class="form-control form-control-sm item_tax_rate"
-          value="${parseFloat(item.tax_rate || 0).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
+          value="${line_tax_rate(item).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
         <input type="hidden" class="item_tax_amount" value="${item.tax_amount || 0}">
       </td>
       <td class="item_total text-end">${format_number((item.quantity || 1) * (item.unit_price || 0), 2)}</td>
@@ -974,7 +974,7 @@
   // ── Boot ─────────────────────────────────────────────────────────────────
   $(async function() {
     try {
-      load_departments('department_id');
+      await Promise.resolve(load_departments('department_id')).catch(function() {});
       await load_location_config();
       await retrieve_warehouses();
 
diff --git a/app/po/po.php b/app/po/po.php
index e86d46c..9a5c3d9 100644
--- a/app/po/po.php
+++ b/app/po/po.php
@@ -226,8 +226,7 @@
     var body      = '';
 
     $.each(page_data, function(i, o) {
-      var items      = JSON.parse(o.items || '[]');
-      var item_count = items.length;
+      var item_count = parseInt(o.item_count) || 0;
       var can_cancel = parseInt(o.status) >= -2 && parseInt(o.status) <= 1;
 
       body += `<tr>
diff --git a/app/po/supplier_returns.php b/app/po/supplier_returns.php
index a376d95..911a6f5 100644
--- a/app/po/supplier_returns.php
+++ b/app/po/supplier_returns.php
@@ -218,9 +218,7 @@
     }
 
     $.each(rows, function(i, r) {
-      var items = [];
-      try { items = JSON.parse(r.items || '[]'); } catch(e) {}
-      var item_count = items.length;
+      var item_count = parseInt(r.item_count) || 0;
       body += `<tr>
         <td class="py-3 fw-semibold">${escape_html(r.return_number || '')}</td>
         <td class="py-3">
diff --git a/app/revenue/api/engine/convert_quotation.php b/app/revenue/api/engine/convert_quotation.php
index e7ff6e8..5ad14ad 100644
--- a/app/revenue/api/engine/convert_quotation.php
+++ b/app/revenue/api/engine/convert_quotation.php
@@ -88,6 +88,7 @@ foreach ($convert_items as $ci) {
         'unit_price'   => $unit_price,
         'total_price'  => $total_price,
         'tax_amount'   => $tax_amount,
+        'tax_rate'     => (float)($qi['tax_rate'] ?? 0),
         'stock_out_id' => 0,
     ];
     $validated[] = ['item_id' => $item_id, 'quantity' => $qty];
diff --git a/app/revenue/manage_order.php b/app/revenue/manage_order.php
index 8d3f93a..e022dd0 100644
--- a/app/revenue/manage_order.php
+++ b/app/revenue/manage_order.php
@@ -235,7 +235,7 @@
       </td>
       <td>
         <input type="number" class="form-control form-control-sm item_tax_rate"
-          value="${parseFloat(item.tax_rate || 0).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
+          value="${line_tax_rate(item).toFixed(2)}" min="0" max="100" step="0.01" oninput="recalc_totals()">
         <input type="hidden" class="item_tax_amount" value="${item.tax_amount || 0}">
       </td>
       <td class="item_total text-end align-middle">
diff --git a/app/revenue/manage_quotation.php b/app/revenue/manage_quotation.php
index dffbc13..abc4aa8 100644
--- a/app/revenue/manage_quotation.php
+++ b/app/revenue/manage_quotation.php
@@ -515,7 +515,7 @@
   // ── Boot ──────────────────────────────────────────────────────────────────
   $(async function() {
     try {
-      load_departments('department_id');
+      await Promise.resolve(load_departments('department_id')).catch(function() {});
       if (quotation_id) {
         await retrieve_quotation();
       } else {
diff --git a/app/revenue/order.php b/app/revenue/order.php
index 050d521..6e55b9f 100644
--- a/app/revenue/order.php
+++ b/app/revenue/order.php
@@ -165,12 +165,6 @@
     return map[String(status)] || '<span class="badge bg-light text-dark">—</span>';
   }
 
-  function order_items_count(items) {
-    if (Array.isArray(items)) return items.length;
-    try { return JSON.parse(items || '[]').length; }
-    catch(e) { return 0; }
-  }
-
   function retrieve_orders() {
     return ajax_request({
       url: '<?php echo $server_url?>order/api/engine/retrieve_order.php',
@@ -226,7 +220,7 @@
     }
 
     $.each(rows, function(i, o) {
-      var item_count = order_items_count(o.items);
+      var item_count = parseInt(o.item_count) || 0;
       var source = String(o.source || '');
       var source_display = source === 'quotation' && parseInt(o.source_id) > 0
         ? `<a href="<?php echo $server_url?>revenue/manage_quotation.php?id=${o.source_id}">Quotation #${o.source_id}</a>`
diff --git a/app/revenue/quotation.php b/app/revenue/quotation.php
index 2784337..27b1fcf 100644
--- a/app/revenue/quotation.php
+++ b/app/revenue/quotation.php
@@ -212,14 +212,14 @@
     var body      = '';
 
     $.each(page_data, function(i, q) {
-      var items = typeof q.items === 'string' ? JSON.parse(q.items || '[]') : (q.items || []);
+      var item_count = parseInt(q.item_count) || 0;
       body += `<tr>
         <td class="py-3 fw-semibold">${escape_html(q.quotation_number)}</td>
         <td class="py-3">${format_date(q.quotation_date)}</td>
         <td class="py-3">${q.valid_until ? format_date(q.valid_until) : '<span class="text-muted">—</span>'}</td>
         <td class="py-3">${escape_html(q.contact_name || '—')}</td>
         <td class="py-3">${get_dept_label(q.department_id)}</td>
-        <td class="py-3">${items.length} item${items.length !== 1 ? 's' : ''}</td>
+        <td class="py-3">${item_count} item${item_count !== 1 ? 's' : ''}</td>
         <td class="py-3 fw-semibold">${format_number(q.grand_total, 2)}</td>
         <td class="py-3">${status_badge[String(q.status)] || q.status}</td>
         <td class="py-3">