diff --git a/MoneyMap/Pages/Receipts.cshtml b/MoneyMap/Pages/Receipts.cshtml
index 0581eec..41e9e6a 100644
--- a/MoneyMap/Pages/Receipts.cshtml
+++ b/MoneyMap/Pages/Receipts.cshtml
@@ -212,6 +212,7 @@
                                             <div class="text-muted">
                                                 @r.TransactionDate?.ToString("yyyy-MM-dd") - @r.TransactionAmount?.ToString("C")
                                             </div>
+                                            <div class="text-muted"><a asp-page="/EditTransaction" asp-route-id="@r.TransactionId" target="_blank">ID #@r.TransactionId</a></div>
                                         </div>
                                     }
                                     else
@@ -266,8 +267,9 @@
                     <h5 class="modal-title" id="mapModalLabel@(r.Id)">Map Receipt to Transaction</h5>
                     <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
                 </div>
-                <form method="post" asp-page-handler="MapToTransaction" asp-route-receiptId="@r.Id">
+                <form method="post" asp-page-handler="MapToTransaction" asp-route-receiptId="@r.Id" data-mapform="1">
                     <div class="modal-body">
+                        <input type="hidden" id="transactionId@(r.Id)" name="transactionId" />
                         <div class="mb-3">
                             <label class="form-label fw-bold">Receipt: @r.FileName</label>
                             @if (!string.IsNullOrWhiteSpace(r.Merchant) || r.ReceiptDate.HasValue || r.DueDate.HasValue || r.Total.HasValue)
@@ -316,7 +318,7 @@
                                     }
                                     Rows highlighted in <span class="badge bg-success">green</span> have matching amounts (within ±2%). Only showing transactions within ±10% of receipt total.
                                 </div>
-                                <input type="hidden" id="transactionId@(r.Id)" name="transactionId" required />
+                                
                                 <div id="transactionListContainer@(r.Id)" style="max-height: 400px; overflow-y: auto; border: 1px solid #dee2e6; border-radius: 0.25rem;">
                                     <table class="table table-sm table-hover mb-0" style="font-size: 0.85rem;">
                                         <thead style="position: sticky; top: 0; background-color: white; z-index: 1;">
@@ -327,6 +329,7 @@
                                                 <th>Name</th>
                                                 <th style="width: 150px;">Merchant</th>
                                                 <th style="width: 100px;">Payment</th>
+                                                <th style="width: 70px;">Edit</th>
                                             </tr>
                                         </thead>
                                         <tbody>
@@ -353,6 +356,7 @@
                                                     <td>@txn.Name</td>
                                                     <td>@(txn.MerchantName ?? "-")</td>
                                                     <td class="small">@txn.PaymentMethod</td>
+                                                    <td><a asp-page="/EditTransaction" asp-route-id="@txn.Id" target="_blank" class="btn btn-sm btn-outline-secondary">Open</a></td>
                                                 </tr>
                                             }
                                         </tbody>
@@ -398,7 +402,7 @@
                         </div>
                         <div class="mb-3">
                             <label for="manualTransactionId@(r.Id)" class="form-label">Or Enter Transaction ID Manually</label>
-                            <input type="number" class="form-control" id="manualTransactionId@(r.Id)" placeholder="Enter transaction ID..."
+                            <input type="number" class="form-control" id="manualTransactionId@(r.Id)" oninput="document.getElementById('transactionId@(r.Id)').value = this.value" placeholder="Enter transaction ID..."
                                    onchange="document.getElementById('transactionId@(r.Id)').value = this.value" />
                         </div>
                     </div>
@@ -411,3 +415,22 @@
         </div>
     </div>
 }
+
+<script>
+  document.addEventListener('DOMContentLoaded', function() {
+    document.querySelectorAll('form[data-mapform="1"]').forEach(function(form){
+      form.addEventListener('submit', function(e){
+        var hidden = form.querySelector('input[type="hidden"][name="transactionId"]');
+        var manual = form.querySelector('input[id^="manualTransactionId"]');
+        if (manual && manual.value) { hidden.value = manual.value; }
+        if (!hidden || !hidden.value) {
+          e.preventDefault();
+          alert('Please select a transaction or enter an ID.');
+        }
+      });
+    });
+  });
+</script>
+
+
+
diff --git a/MoneyMap/Pages/Receipts.cshtml.cs b/MoneyMap/Pages/Receipts.cshtml.cs
index d0f377f..548bf5d 100644
--- a/MoneyMap/Pages/Receipts.cshtml.cs
+++ b/MoneyMap/Pages/Receipts.cshtml.cs
@@ -140,6 +140,41 @@ namespace MoneyMap.Pages
 
         public async Task<IActionResult> OnPostMapToTransactionAsync(long receiptId, long transactionId)
         {
+            if (transactionId <= 0)
+            {
+                Message = "Please select a transaction or enter a valid ID.";
+                IsSuccess = false;
+                return RedirectToPage();
+            }
+
+            var receipt = await _db.Receipts.FirstOrDefaultAsync(r => r.Id == receiptId);
+            if (receipt == null)
+            {
+                Message = $"Receipt not found (ID {receiptId}).";
+                IsSuccess = false;
+                return RedirectToPage();
+            }
+
+            var transactionExists = await _db.Transactions.AnyAsync(t => t.Id == transactionId);
+            if (!transactionExists)
+            {
+                Message = $"Transaction not found (ID {transactionId}).";
+                IsSuccess = false;
+                return RedirectToPage();
+            }
+
+            // Friendly duplicate check: same file already mapped to this transaction
+            if (!string.IsNullOrWhiteSpace(receipt.FileHashSha256))
+            {
+                var duplicateExists = await _db.Receipts.AnyAsync(r => r.Id != receiptId && r.TransactionId == transactionId && r.FileHashSha256 == receipt.FileHashSha256);
+                if (duplicateExists)
+                {
+                    Message = "This transaction already has a receipt with the same file (duplicate prevented).";
+                    IsSuccess = false;
+                    return RedirectToPage();
+                }
+            }
+
             var success = await _receiptManager.MapReceiptToTransactionAsync(receiptId, transactionId);
 
             if (success)
@@ -393,3 +428,4 @@ namespace MoneyMap.Pages
         }
     }
 }
+
diff --git a/MoneyMap/Services/ReceiptManager.cs b/MoneyMap/Services/ReceiptManager.cs
index a6d9c3e..129071a 100644
--- a/MoneyMap/Services/ReceiptManager.cs
+++ b/MoneyMap/Services/ReceiptManager.cs
@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.EntityFrameworkCore;
 using MoneyMap.Data;
@@ -206,12 +206,9 @@ namespace MoneyMap.Services
             if (transaction == null)
                 return false;
 
-            // Check if this receipt is already mapped to another transaction
-            if (receipt.TransactionId.HasValue && receipt.TransactionId.Value != transactionId)
-            {
-                // Could return a more specific error, but for now just return false
-                return false;
-            }
+            // Allow remapping: simply update the TransactionId
+            if (receipt.TransactionId == transactionId)
+                return true;
 
             receipt.TransactionId = transactionId;
             await _db.SaveChangesAsync();
@@ -228,7 +225,7 @@ namespace MoneyMap.Services
             var sanitized = new StringBuilder();
             foreach (var c in fileName)
             {
-                if (c == '®' || c == '™' || c == '©')
+                if (c == '®' || c == '™' || c == '©')
                 {
                     // Skip trademark/copyright symbols
                     continue;
@@ -313,4 +310,4 @@ namespace MoneyMap.Services
         public string? TransactionName { get; set; }
         public string Reason { get; set; } = "";
     }
-}
\ No newline at end of file
+}