Add BatchId to GiftCertificate for persistent bulk batch tracking

BatchId (Guid?) is stamped on every certificate in a bulk run so the batch
is permanently addressable. BulkResult is now a bookmarkable GET by batchId
rather than TempData, so users can return to re-download at any time.
BatchDownloadPdf is a GET link (no form POST needed). Index shows a Batch
badge on bulk certs that links directly back to the batch result page.

Migration: AddGiftCertificateBatchId

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Web/Controllers/GiftCertificatesController.cs

@@ -107,7 +107,8 @@ public class GiftCertificatesController : Controller
                 IssuedReason = gc.IssuedReason,
                 Status = gc.Status,
                 IssueDate = gc.IssueDate,
-                ExpiryDate = gc.ExpiryDate
+                ExpiryDate = gc.ExpiryDate,
+                BatchId = gc.BatchId
             })
             .ToList();
 
@@ -487,7 +488,7 @@ public class GiftCertificatesController : Controller
                 discountAcctId = acct?.Id;
             }
 
-            var createdIds = new List<int>();
+            var batchId = Guid.NewGuid();
             var now = DateTime.UtcNow;
 
             for (int i = 0; i < dto.Quantity; i++)
@@ -507,12 +508,12 @@ public class GiftCertificatesController : Controller
                     IssuedById = currentUser?.Id,
                     CompanyId = companyId,
                     CreatedAt = now,
-                    CreatedBy = currentUser?.Email
+                    CreatedBy = currentUser?.Email,
+                    BatchId = batchId
                 };
 
                 await _unitOfWork.GiftCertificates.AddAsync(cert);
                 await _unitOfWork.CompleteAsync();
-                createdIds.Add(cert.Id);
 
                 await _accountBalanceService.CreditAsync(gcLiabilityAcctId, cert.OriginalAmount);
                 if (dto.IssuedReason == GiftCertificateIssuedReason.Sold)
@@ -521,10 +522,7 @@ public class GiftCertificatesController : Controller
                     await _accountBalanceService.DebitAsync(discountAcctId, cert.OriginalAmount);
             }
 
-            TempData["BulkCertIds"] = System.Text.Json.JsonSerializer.Serialize(createdIds);
-            TempData["BulkCertCount"] = dto.Quantity;
-            TempData["BulkCertAmount"] = dto.Amount.ToString("F2");
-            return RedirectToAction(nameof(BulkResult));
+            return RedirectToAction(nameof(BulkResult), new { batchId });
         }
         catch (Exception ex)
         {
@@ -535,31 +533,30 @@ public class GiftCertificatesController : Controller
     }
 
     /// <summary>
-    /// Displays the bulk creation confirmation page with the list of generated certificate codes
-    /// and a button to download all as a single print-ready PDF.
+    /// Displays the batch confirmation page. Driven by BatchId so it is bookmarkable and survives
+    /// browser back/refresh — the user can return here any time to re-download the batch PDF.
     /// </summary>
-    public async Task<IActionResult> BulkResult()
+    public async Task<IActionResult> BulkResult(Guid batchId)
     {
-        if (TempData["BulkCertIds"] is not string json)
+        if (batchId == Guid.Empty)
             return RedirectToAction(nameof(Index));
 
-        var ids = System.Text.Json.JsonSerializer.Deserialize<List<int>>(json) ?? new();
-        var certs = await _unitOfWork.GiftCertificates.FindAsync(gc => ids.Contains(gc.Id), false);
+        var certs = await _unitOfWork.GiftCertificates.FindAsync(
+            gc => gc.BatchId == batchId, false);
+
+        if (!certs.Any())
+            return RedirectToAction(nameof(Index));
 
-        ViewBag.CertCount = TempData["BulkCertCount"];
-        ViewBag.CertAmount = TempData["BulkCertAmount"];
-        ViewBag.CertIds = ids;
         return View(certs.OrderBy(c => c.CertificateCode).ToList());
     }
 
     /// <summary>
-    /// Generates and streams a single PDF containing one page per certificate in the batch.
-    /// The certificate IDs are posted as a form array so there is no URL-length limit on batch size.
+    /// Streams a multi-page PDF for an entire batch identified by BatchId. GET endpoint so the
+    /// user can bookmark or re-open it at any time after the batch was originally created.
     /// </summary>
-    [HttpPost, ValidateAntiForgeryToken]
-    public async Task<IActionResult> BulkDownloadPdf(int[] certIds)
+    public async Task<IActionResult> BatchDownloadPdf(Guid batchId)
     {
-        if (certIds == null || certIds.Length == 0)
+        if (batchId == Guid.Empty)
             return BadRequest();
 
         var currentUser = await _userManager.GetUserAsync(User);
@@ -578,9 +575,12 @@ public class GiftCertificatesController : Controller
         };
 
         var certs = await _unitOfWork.GiftCertificates.FindAsync(
-            gc => certIds.Contains(gc.Id), false,
+            gc => gc.BatchId == batchId, false,
             gc => gc.RecipientCustomer);
 
+        if (!certs.Any())
+            return NotFound();
+
         var dtos = certs.OrderBy(c => c.CertificateCode).Select(cert => new GiftCertificateDto
         {
             Id = cert.Id,
@@ -603,18 +603,18 @@ public class GiftCertificatesController : Controller
         {
             var (logoData, logoContentType) = await LoadCompanyLogoAsync(company);
             var pdfBytes = await _pdfService.GenerateBulkGiftCertificatePdfAsync(dtos, logoData, logoContentType, companyInfo);
-            var firstName = dtos.FirstOrDefault()?.CertificateCode ?? "batch";
-            var lastName = dtos.LastOrDefault()?.CertificateCode ?? string.Empty;
+            var first = dtos.First().CertificateCode;
+            var last = dtos.Last().CertificateCode;
             var fileName = dtos.Count == 1
-                ? $"GiftCertificate-{firstName}.pdf"
-                : $"GiftCertificates-{firstName}-to-{lastName}.pdf";
+                ? $"GiftCertificate-{first}.pdf"
+                : $"GiftCertificates-{first}-to-{last}.pdf";
             return File(pdfBytes, "application/pdf", fileName);
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Error generating bulk gift certificate PDF");
+            _logger.LogError(ex, "Error generating batch gift certificate PDF for batch {BatchId}", batchId);
             TempData["Error"] = "Could not generate PDF.";
-            return RedirectToAction(nameof(Index));
+            return RedirectToAction(nameof(BulkResult), new { batchId });
         }
     }
 

src/PowderCoating.Web/Views/GiftCertificates/BulkResult.cshtml

@@ -2,41 +2,35 @@
 @using PowderCoating.Core.Enums
 
 @{
-    ViewData["Title"] = "Batch Created";
+    ViewData["Title"] = "Batch Gift Certificates";
     ViewData["PageIcon"] = "bi-gift";
-    var count = ViewBag.CertCount as int? ?? Model.Count;
-    var amount = ViewBag.CertAmount as string ?? "0.00";
-    var ids = ViewBag.CertIds as List<int> ?? Model.Select(c => c.Id).ToList();
+    var batchId = Model.FirstOrDefault()?.BatchId ?? Guid.Empty;
+    var count = Model.Count;
+    var amount = Model.FirstOrDefault()?.OriginalAmount ?? 0m;
 }
 
 <div class="alert alert-success alert-permanent mb-4">
     <i class="bi bi-check-circle-fill me-2"></i>
-    <strong>@count gift certificates created</strong> &mdash; each worth $@amount.
-    Download the PDF below to print the full batch.
+    <strong>@count gift certificates created</strong> &mdash; each worth @amount.ToString("C").
+    Download the PDF below to print the full batch. This page is bookmarkable &mdash; you can return here any time to re-download.
 </div>
 
 <div class="card border-0 shadow-sm mb-4">
     <div class="card-header bg-white border-bottom d-flex justify-content-between align-items-center py-3">
         <h5 class="mb-0">
             <i class="bi bi-collection me-2 text-primary"></i>Batch Certificates (@count)
+            <span class="text-muted small fw-normal ms-2 font-monospace">@batchId.ToString("N")[..8]&hellip;</span>
         </h5>
-        <form asp-action="BulkDownloadPdf" method="post">
-            @Html.AntiForgeryToken()
-            @foreach (var id in ids)
-            {
-                <input type="hidden" name="certIds" value="@id" />
-            }
-            <button type="submit" class="btn btn-primary">
-                <i class="bi bi-file-pdf me-2"></i>Download All as PDF
-            </button>
-        </form>
+        <a asp-action="BatchDownloadPdf" asp-route-batchId="@batchId" class="btn btn-primary">
+            <i class="bi bi-file-pdf me-2"></i>Download All as PDF
+        </a>
     </div>
     <div class="card-body p-0">
         <div class="table-responsive">
             <table class="table table-hover mb-0">
                 <thead class="table-light">
                     <tr>
-                        <th>Certificate Code</th>
+                        <th class="ps-3">Certificate Code</th>
                         <th>Face Value</th>
                         <th>Issued</th>
                         <th>Expiry</th>
@@ -48,7 +42,7 @@
                     @foreach (var cert in Model)
                     {
                         <tr>
-                            <td class="fw-mono fw-semibold">@cert.CertificateCode</td>
+                            <td class="ps-3 fw-semibold font-monospace">@cert.CertificateCode</td>
                             <td>@cert.OriginalAmount.ToString("C")</td>
                             <td>@cert.IssueDate.ToLocalTime().ToString("MMM d, yyyy")</td>
                             <td>
@@ -58,7 +52,7 @@
                             </td>
                             <td><span class="badge bg-success">Active</span></td>
                             <td class="text-end">
-                                <a asp-action="Details" asp-route-id="@cert.Id" class="btn btn-sm btn-outline-secondary">
+                                <a asp-action="Details" asp-route-id="@cert.Id" class="btn btn-sm btn-outline-secondary" title="View details">
                                     <i class="bi bi-eye"></i>
                                 </a>
                                 <a asp-action="DownloadPdf" asp-route-id="@cert.Id" class="btn btn-sm btn-outline-secondary" title="Download single PDF">
@@ -75,15 +69,8 @@
         <a asp-action="Index" class="btn btn-outline-secondary">
             <i class="bi bi-arrow-left me-1"></i>Back to Gift Certificates
         </a>
-        <form asp-action="BulkDownloadPdf" method="post">
-            @Html.AntiForgeryToken()
-            @foreach (var id in ids)
-            {
-                <input type="hidden" name="certIds" value="@id" />
-            }
-            <button type="submit" class="btn btn-primary">
-                <i class="bi bi-printer me-2"></i>Print Batch PDF (@count pages)
-            </button>
-        </form>
+        <a asp-action="BatchDownloadPdf" asp-route-batchId="@batchId" class="btn btn-primary">
+            <i class="bi bi-printer me-2"></i>Print Batch PDF (@count pages)
+        </a>
     </div>
 </div>

src/PowderCoating.Web/Views/GiftCertificates/Index.cshtml

@@ -80,6 +80,14 @@ else
                                     <a asp-action="Details" asp-route-id="@cert.Id" class="fw-semibold text-decoration-none font-monospace">
                                         @cert.CertificateCode
                                     </a>
+                                    @if (cert.BatchId.HasValue)
+                                    {
+                                        <a asp-action="BulkResult" asp-route-batchId="@cert.BatchId"
+                                           class="badge bg-primary-subtle text-primary text-decoration-none ms-1"
+                                           title="View &amp; download batch">
+                                            <i class="bi bi-collection me-1"></i>Batch
+                                        </a>
+                                    }
                                 </td>
                                 <td>
                                     @if (!string.IsNullOrEmpty(cert.RecipientName))
@@ -88,7 +96,7 @@ else
                                     }
                                     else
                                     {
-                                        <span class="text-muted">—</span>
+                                        <span class="text-muted">&mdash;</span>
                                     }
                                     @if (!string.IsNullOrEmpty(cert.RecipientEmail))
                                     {