Guard bulk-action buttons against double-submit (#36)

The 4 bulk-action confirm buttons (close/assign/priority/status) called
their performBulk*() handler directly on click with no in-flight guard.
Double-clicking a confirm button fired two concurrent POST /api/
bulk_operation.php requests for the same ticket IDs, duplicating the
close-reason comment, audit-log entry, and Matrix notification on every
affected ticket.

Each performBulk*() function now takes the clicked button, no-ops if
it's already disabled, disables it before firing the request, and
re-enables it in .finally() regardless of outcome.

Verified by extracting performBulkAssign() from the real source and
driving it with a mock lt.api.post() that never resolves until told to:
a simulated rapid double-click fired exactly one request (the second
call was a no-op while the button was disabled), and a subsequent click
after the request resolved correctly fired a new request.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0117oBw2jN4kALYeS8HPq4zV

assets/js/dashboard.js

@@ -140,25 +140,25 @@ document.addEventListener('DOMContentLoaded', function() {
                 break;
             // Bulk operation perform actions
             case 'perform-bulk-assign':
-                performBulkAssign();
+                performBulkAssign(target);
                 break;
             case 'close-bulk-assign-modal':
                 closeBulkAssignModal();
                 break;
             case 'perform-bulk-priority':
-                performBulkPriority();
+                performBulkPriority(target);
                 break;
             case 'close-bulk-priority-modal':
                 closeBulkPriorityModal();
                 break;
             case 'perform-bulk-status':
-                performBulkStatusChange();
+                performBulkStatusChange(target);
                 break;
             case 'close-bulk-status-modal':
                 closeBulkStatusModal();
                 break;
             case 'perform-bulk-close':
-                performBulkCloseAction();
+                performBulkCloseAction(undefined, target);
                 break;
             case 'close-bulk-close-modal':
                 closeBulkCloseModal();
@@ -491,7 +491,10 @@ function closeBulkCloseModal() {
     if (modal) setTimeout(() => modal.remove(), 300);
 }
 
-function performBulkCloseAction(ticketIds) {
+function performBulkCloseAction(ticketIds, btn) {
+    if (btn && btn.disabled) return; // already in flight — guards against a double-click firing two requests
+    if (btn) btn.disabled = true;
+
     ticketIds = ticketIds || getSelectedTicketIds();
     const commentEl = document.getElementById('bulkCloseComment');
     const comment = commentEl ? commentEl.value.trim() : '';
@@ -524,7 +527,8 @@ function performBulkCloseAction(ticketIds) {
         }
         closeBulkCloseModal();
         lt.toast.error('Bulk close failed: ' + error.message, 5000);
-    });
+    })
+    .finally(() => { if (btn) btn.disabled = false; });
 }
 
 var _bulkAssignUserId = null;
@@ -596,7 +600,8 @@ function closeBulkAssignModal() {
     if (modal) setTimeout(() => modal.remove(), 300);
 }
 
-function performBulkAssign() {
+function performBulkAssign(btn) {
+    if (btn && btn.disabled) return; // already in flight — guards against a double-click firing two requests
     const userId = _bulkAssignUserId;
     const ticketIds = getSelectedTicketIds();
 
@@ -605,6 +610,8 @@ function performBulkAssign() {
         return;
     }
 
+    if (btn) btn.disabled = true;
+
     lt.api.post('/api/bulk_operation.php', {
         operation_type: 'bulk_assign',
         ticket_ids: ticketIds,
@@ -625,7 +632,8 @@ function performBulkAssign() {
     })
     .catch(error => {
         lt.toast.error('Bulk assign failed: ' + error.message, 5000);
-    });
+    })
+    .finally(() => { if (btn) btn.disabled = false; });
 }
 
 function showBulkPriorityModal() {
@@ -672,7 +680,8 @@ function closeBulkPriorityModal() {
     if (modal) setTimeout(() => modal.remove(), 300);
 }
 
-function performBulkPriority() {
+function performBulkPriority(btn) {
+    if (btn && btn.disabled) return; // already in flight — guards against a double-click firing two requests
     const priorityEl = document.getElementById('bulkPriority');
     if (!priorityEl) return;
     const priority = priorityEl.value;
@@ -683,6 +692,8 @@ function performBulkPriority() {
         return;
     }
 
+    if (btn) btn.disabled = true;
+
     lt.api.post('/api/bulk_operation.php', {
         operation_type: 'bulk_priority',
         ticket_ids: ticketIds,
@@ -703,7 +714,8 @@ function performBulkPriority() {
     })
     .catch(error => {
         lt.toast.error('Bulk priority update failed: ' + error.message, 5000);
-    });
+    })
+    .finally(() => { if (btn) btn.disabled = false; });
 }
 
 // Make table rows clickable
@@ -786,7 +798,8 @@ function closeBulkStatusModal() {
     if (modal) setTimeout(() => modal.remove(), 300);
 }
 
-function performBulkStatusChange() {
+function performBulkStatusChange(btn) {
+    if (btn && btn.disabled) return; // already in flight — guards against a double-click firing two requests
     const bulkStatusEl = document.getElementById('bulkStatus');
     if (!bulkStatusEl) return;
     const status = bulkStatusEl.value;
@@ -800,6 +813,8 @@ function performBulkStatusChange() {
     const commentEl = document.getElementById('bulkStatusComment');
     const comment = commentEl ? commentEl.value.trim() : '';
 
+    if (btn) btn.disabled = true;
+
     lt.api.post('/api/bulk_operation.php', {
         operation_type: 'bulk_status',
         ticket_ids: ticketIds,
@@ -829,7 +844,8 @@ function performBulkStatusChange() {
         }
         closeBulkStatusModal();
         lt.toast.error('Bulk status change failed: ' + error.message, 5000);
-    });
+    })
+    .finally(() => { if (btn) btn.disabled = false; });
 }
 
 /**