feat: add JoeAppEngine OPC UA nodes, fix DCL auto-reconnect and quality push

- Add JoeAppEngine folder to OPC UA nodes.json (BTCS, AlarmCntsBySeverity, Scheduler/ScanTime)
- Fix DataConnectionActor: capture Self in PreStart for use from non-actor threads,
  preventing Self.Tell failure in Disconnected event handler
- Implement InstanceActor.HandleConnectionQualityChanged to mark attributes Bad on disconnect
- Fix LmxFakeProxy TagMapper to serialize arrays as JSON instead of "System.Int32[]"
- Allow DataType and DataSourceReference updates in TemplateService.UpdateAttributeAsync
- Update test_infra_opcua.md with JoeAppEngine documentation

src/ScadaLink.CentralUI/Components/Pages/Deployment/Instances.razor

@@ -65,6 +65,16 @@
                                 }
                             </select>
                         </div>
+                        <div class="col-md-2">
+                            <label class="form-label small">Area</label>
+                            <select class="form-select form-select-sm" @bind="_createAreaId">
+                                <option value="0">No area</option>
+                                @foreach (var a in _allAreas.Where(a => a.SiteId == _createSiteId))
+                                {
+                                    <option value="@a.Id">@a.Name</option>
+                                }
+                            </select>
+                        </div>
                         <div class="col-md-2">
                             <button class="btn btn-success btn-sm me-1" @onclick="CreateInstance">Create</button>
                             <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showCreateForm = false">Cancel</button>
@@ -181,10 +191,62 @@
                             }
                             <button class="btn btn-outline-info btn-sm py-0 px-1 me-1"
                                     @onclick="() => ToggleBindings(inst)">Bindings</button>
+                            <button class="btn btn-outline-secondary btn-sm py-0 px-1 me-1"
+                                    @onclick="() => ToggleOverrides(inst)">Overrides</button>
+                            <button class="btn btn-outline-info btn-sm py-0 px-1 me-1"
+                                    @onclick="() => ShowDiff(inst)" disabled="@(_actionInProgress || inst.State == InstanceState.NotDeployed)">Diff</button>
                             <button class="btn btn-outline-danger btn-sm py-0 px-1"
                                     @onclick="() => DeleteInstance(inst)" disabled="@_actionInProgress">Delete</button>
                         </td>
                     </tr>
+                    @if (_overrideInstanceId == inst.Id)
+                    {
+                        <tr>
+                            <td colspan="7" class="bg-light p-3">
+                                <div class="d-flex justify-content-between align-items-center mb-2">
+                                    <strong>Attribute Overrides for @inst.UniqueName</strong>
+                                    <div>
+                                        <label class="form-label small d-inline me-1">Reassign Area:</label>
+                                        <select class="form-select form-select-sm d-inline-block me-1" style="width:auto;" @bind="_reassignAreaId">
+                                            <option value="0">No area</option>
+                                            @foreach (var a in _allAreas.Where(a => a.SiteId == inst.SiteId))
+                                            {
+                                                <option value="@a.Id">@a.Name</option>
+                                            }
+                                        </select>
+                                        <button class="btn btn-sm btn-outline-primary" @onclick="() => ReassignArea(inst)" disabled="@_actionInProgress">Set Area</button>
+                                    </div>
+                                </div>
+                                @if (_overrideAttrs.Count == 0)
+                                {
+                                    <p class="text-muted small mb-0">No overridable (non-locked) attributes in this template.</p>
+                                }
+                                else
+                                {
+                                    <table class="table table-sm table-bordered mb-2">
+                                        <thead class="table-light">
+                                            <tr><th>Attribute</th><th>Template Value</th><th>Override Value</th></tr>
+                                        </thead>
+                                        <tbody>
+                                            @foreach (var attr in _overrideAttrs)
+                                            {
+                                                <tr>
+                                                    <td class="small">@attr.Name <span class="badge bg-light text-dark">@attr.DataType</span></td>
+                                                    <td class="small text-muted">@(attr.Value ?? "—")</td>
+                                                    <td>
+                                                        <input type="text" class="form-control form-control-sm"
+                                                               value="@GetOverrideValue(attr.Name)"
+                                                               @onchange="(e) => OnOverrideChanged(attr.Name, e)" />
+                                                    </td>
+                                                </tr>
+                                            }
+                                        </tbody>
+                                    </table>
+                                    <button class="btn btn-success btn-sm" @onclick="SaveOverrides" disabled="@_actionInProgress">Save Overrides</button>
+                                }
+                            </td>
+                        </tr>
+                    }
                     @if (_bindingInstanceId == inst.Id)
                     {
                         <tr>
@@ -268,6 +330,55 @@
         <div class="text-muted small">
             @_filteredInstances.Count instance(s) total
         </div>
+
+        @* Diff Modal *@
+        @if (_showDiffModal)
+        {
+            <div class="modal d-block" tabindex="-1" style="background-color: rgba(0,0,0,0.5);">
+                <div class="modal-dialog modal-lg">
+                    <div class="modal-content">
+                        <div class="modal-header">
+                            <h5 class="modal-title">Deployment Diff — @_diffInstanceName</h5>
+                            <button type="button" class="btn-close" @onclick="() => _showDiffModal = false"></button>
+                        </div>
+                        <div class="modal-body">
+                            @if (_diffLoading)
+                            {
+                                <LoadingSpinner IsLoading="true" />
+                            }
+                            else if (_diffError != null)
+                            {
+                                <div class="alert alert-danger">@_diffError</div>
+                            }
+                            else if (_diffResult != null)
+                            {
+                                <div class="mb-2">
+                                    <span class="badge @(_diffResult.IsStale ? "bg-warning text-dark" : "bg-success")">
+                                        @(_diffResult.IsStale ? "Stale — changes pending" : "Current")
+                                    </span>
+                                    <span class="text-muted small ms-2">
+                                        Deployed: @_diffResult.DeployedRevisionHash[..8]
+                                        | Current: @_diffResult.CurrentRevisionHash[..8]
+                                        | Deployed at: @_diffResult.DeployedAt.LocalDateTime.ToString("yyyy-MM-dd HH:mm")
+                                    </span>
+                                </div>
+                                @if (!_diffResult.IsStale)
+                                {
+                                    <p class="text-muted">No differences between deployed and current configuration.</p>
+                                }
+                                else
+                                {
+                                    <p class="text-muted small">The deployed revision hash differs from the current template-derived hash. Redeploy to apply changes.</p>
+                                }
+                            }
+                        </div>
+                        <div class="modal-footer">
+                            <button class="btn btn-secondary btn-sm" @onclick="() => _showDiffModal = false">Close</button>
+                        </div>
+                    </div>
+                </div>
+            </div>
+        }
     }
 </div>
 
@@ -508,6 +619,7 @@
     private string _createName = string.Empty;
     private int _createTemplateId;
     private int _createSiteId;
+    private int _createAreaId;
     private string? _createError;
 
     private void ShowCreateForm()
@@ -515,6 +627,7 @@
         _createName = string.Empty;
         _createTemplateId = 0;
         _createSiteId = 0;
+        _createAreaId = 0;
         _createError = null;
         _showCreateForm = true;
     }
@@ -530,7 +643,7 @@
         {
             var user = await GetCurrentUserAsync();
             var result = await InstanceService.CreateInstanceAsync(
-                _createName.Trim(), _createTemplateId, _createSiteId, null, user);
+                _createName.Trim(), _createTemplateId, _createSiteId, _createAreaId == 0 ? null : _createAreaId, user);
             if (result.IsSuccess)
             {
                 _showCreateForm = false;
@@ -548,6 +661,118 @@
         }
     }
 
+    // Override state
+    private int _overrideInstanceId;
+    private List<TemplateAttribute> _overrideAttrs = new();
+    private Dictionary<string, string?> _overrideValues = new();
+    private int _reassignAreaId;
+
+    private async Task ToggleOverrides(Instance inst)
+    {
+        if (_overrideInstanceId == inst.Id) { _overrideInstanceId = 0; return; }
+        _overrideInstanceId = inst.Id;
+        _overrideValues.Clear();
+        _reassignAreaId = inst.AreaId ?? 0;
+
+        var attrs = await TemplateEngineRepository.GetAttributesByTemplateIdAsync(inst.TemplateId);
+        _overrideAttrs = attrs.Where(a => !a.IsLocked).ToList();
+
+        var overrides = await TemplateEngineRepository.GetOverridesByInstanceIdAsync(inst.Id);
+        foreach (var o in overrides)
+        {
+            _overrideValues[o.AttributeName] = o.OverrideValue;
+        }
+    }
+
+    private string? GetOverrideValue(string attrName) =>
+        _overrideValues.GetValueOrDefault(attrName);
+
+    private void OnOverrideChanged(string attrName, ChangeEventArgs e)
+    {
+        var val = e.Value?.ToString();
+        if (string.IsNullOrEmpty(val))
+            _overrideValues.Remove(attrName);
+        else
+            _overrideValues[attrName] = val;
+    }
+
+    private async Task SaveOverrides()
+    {
+        _actionInProgress = true;
+        try
+        {
+            var user = await GetCurrentUserAsync();
+            foreach (var (attrName, value) in _overrideValues)
+            {
+                await InstanceService.SetAttributeOverrideAsync(_overrideInstanceId, attrName, value, user);
+            }
+            _toast.ShowSuccess($"Saved {_overrideValues.Count} override(s).");
+            _overrideInstanceId = 0;
+        }
+        catch (Exception ex)
+        {
+            _toast.ShowError($"Save overrides failed: {ex.Message}");
+        }
+        _actionInProgress = false;
+    }
+
+    private async Task ReassignArea(Instance inst)
+    {
+        _actionInProgress = true;
+        try
+        {
+            var user = await GetCurrentUserAsync();
+            var result = await InstanceService.AssignToAreaAsync(inst.Id, _reassignAreaId == 0 ? null : _reassignAreaId, user);
+            if (result.IsSuccess)
+            {
+                _toast.ShowSuccess($"Area reassigned for '{inst.UniqueName}'.");
+                await LoadDataAsync();
+            }
+            else
+            {
+                _toast.ShowError($"Reassign failed: {result.Error}");
+            }
+        }
+        catch (Exception ex)
+        {
+            _toast.ShowError($"Reassign failed: {ex.Message}");
+        }
+        _actionInProgress = false;
+    }
+
+    // Diff state
+    private bool _showDiffModal;
+    private bool _diffLoading;
+    private string? _diffError;
+    private string _diffInstanceName = string.Empty;
+    private DeploymentComparisonResult? _diffResult;
+
+    private async Task ShowDiff(Instance inst)
+    {
+        _showDiffModal = true;
+        _diffLoading = true;
+        _diffError = null;
+        _diffResult = null;
+        _diffInstanceName = inst.UniqueName;
+        try
+        {
+            var result = await DeploymentService.GetDeploymentComparisonAsync(inst.Id);
+            if (result.IsSuccess)
+            {
+                _diffResult = result.Value;
+            }
+            else
+            {
+                _diffError = result.Error;
+            }
+        }
+        catch (Exception ex)
+        {
+            _diffError = $"Failed to load diff: {ex.Message}";
+        }
+        _diffLoading = false;
+    }
+
     // Connection binding state
     private int _bindingInstanceId;
     private List<TemplateAttribute> _bindingDataSourceAttrs = new();

src/ScadaLink.CentralUI/Components/Pages/Design/ExternalSystems.razor

@@ -50,8 +50,8 @@
 
         @if (_tab == "extsys") { @RenderExternalSystems() }
         else if (_tab == "dbconn") { @RenderDbConnections() }
-        else if (_tab == "notif") { @RenderNotificationLists() }
-        else if (_tab == "inbound") { @RenderInboundApiMethods() }
+        else if (_tab == "notif") { @RenderNotificationLists() @RenderSmtpConfig() }
+        else if (_tab == "inbound") { @RenderInboundApiMethods() @RenderApiKeyMethodAssignments() }
     }
 </div>
 
@@ -66,6 +66,8 @@
     private ExternalSystemDefinition? _editingExtSys;
     private string _extSysName = "", _extSysUrl = "", _extSysAuth = "ApiKey";
     private string? _extSysAuthConfig;
+    private int _extSysMaxRetries = 3;
+    private int _extSysRetryDelaySeconds = 5;
     private string? _extSysFormError;
 
     // Database Connections
@@ -73,8 +75,21 @@
     private bool _showDbConnForm;
     private DatabaseConnectionDefinition? _editingDbConn;
     private string _dbConnName = "", _dbConnString = "";
+    private int _dbConnMaxRetries = 3;
+    private int _dbConnRetryDelaySeconds = 5;
     private string? _dbConnFormError;
 
+    // SMTP Configuration
+    private List<SmtpConfiguration> _smtpConfigs = new();
+    private bool _showSmtpForm;
+    private SmtpConfiguration? _editingSmtp;
+    private string _smtpHost = "", _smtpFromAddress = "", _smtpAuthType = "OAuth2";
+    private int _smtpPort = 587;
+    private string? _smtpFormError;
+
+    // API Key list
+    private List<ApiKey> _apiKeys = new();
+
     // Notification Lists
     private List<NotificationList> _notificationLists = new();
     private bool _showNotifForm;
@@ -123,6 +138,8 @@
             }
 
             _apiMethods = (await InboundApiRepository.GetAllApiMethodsAsync()).ToList();
+            _smtpConfigs = (await NotificationRepository.GetAllSmtpConfigurationsAsync()).ToList();
+            _apiKeys = (await InboundApiRepository.GetAllApiKeysAsync()).ToList();
         }
         catch (Exception ex) { _errorMessage = ex.Message; }
         _loading = false;
@@ -144,8 +161,10 @@
                     <div class="col-md-3"><label class="form-label small">Endpoint URL</label><input type="text" class="form-control form-control-sm" @bind="_extSysUrl" /></div>
                     <div class="col-md-2"><label class="form-label small">Auth Type</label>
                         <select class="form-select form-select-sm" @bind="_extSysAuth"><option>ApiKey</option><option>BasicAuth</option></select></div>
-                    <div class="col-md-3"><label class="form-label small">Auth Config (JSON)</label><input type="text" class="form-control form-control-sm" @bind="_extSysAuthConfig" /></div>
-                    <div class="col-md-2">
+                    <div class="col-md-2"><label class="form-label small">Auth Config (JSON)</label><input type="text" class="form-control form-control-sm" @bind="_extSysAuthConfig" /></div>
+                    <div class="col-md-1"><label class="form-label small">Max Retries</label><input type="number" class="form-control form-control-sm" @bind="_extSysMaxRetries" min="0" /></div>
+                    <div class="col-md-1"><label class="form-label small">Retry Delay (s)</label><input type="number" class="form-control form-control-sm" @bind="_extSysRetryDelaySeconds" min="0" /></div>
+                    <div class="col-md-1">
                         <button class="btn btn-success btn-sm me-1" @onclick="SaveExtSys">Save</button>
                         <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showExtSysForm = false">Cancel</button></div>
                 </div>
@@ -154,14 +173,15 @@
         }
 
         <table class="table table-sm table-striped">
-            <thead class="table-dark"><tr><th>Name</th><th>URL</th><th>Auth</th><th style="width:120px;">Actions</th></tr></thead>
+            <thead class="table-dark"><tr><th>Name</th><th>URL</th><th>Auth</th><th>Retries</th><th>Delay</th><th style="width:120px;">Actions</th></tr></thead>
             <tbody>
                 @foreach (var es in _externalSystems)
                 {
                     <tr>
                         <td>@es.Name</td><td class="small">@es.EndpointUrl</td><td><span class="badge bg-secondary">@es.AuthType</span></td>
+                        <td class="small">@es.MaxRetries</td><td class="small">@es.RetryDelay.TotalSeconds s</td>
                         <td>
-                            <button class="btn btn-outline-primary btn-sm py-0 px-1 me-1" @onclick="() => { _editingExtSys = es; _extSysName = es.Name; _extSysUrl = es.EndpointUrl; _extSysAuth = es.AuthType; _extSysAuthConfig = es.AuthConfiguration; _showExtSysForm = true; }">Edit</button>
+                            <button class="btn btn-outline-primary btn-sm py-0 px-1 me-1" @onclick="() => { _editingExtSys = es; _extSysName = es.Name; _extSysUrl = es.EndpointUrl; _extSysAuth = es.AuthType; _extSysAuthConfig = es.AuthConfiguration; _extSysMaxRetries = es.MaxRetries; _extSysRetryDelaySeconds = (int)es.RetryDelay.TotalSeconds; _showExtSysForm = true; }">Edit</button>
                             <button class="btn btn-outline-danger btn-sm py-0 px-1" @onclick="() => DeleteExtSys(es)">Delete</button>
                         </td>
                     </tr>
@@ -177,6 +197,8 @@
         _extSysName = _extSysUrl = string.Empty;
         _extSysAuth = "ApiKey";
         _extSysAuthConfig = null;
+        _extSysMaxRetries = 3;
+        _extSysRetryDelaySeconds = 5;
         _extSysFormError = null;
     }
 
@@ -186,8 +208,8 @@
         if (string.IsNullOrWhiteSpace(_extSysName) || string.IsNullOrWhiteSpace(_extSysUrl)) { _extSysFormError = "Name and URL required."; return; }
         try
         {
-            if (_editingExtSys != null) { _editingExtSys.Name = _extSysName.Trim(); _editingExtSys.EndpointUrl = _extSysUrl.Trim(); _editingExtSys.AuthType = _extSysAuth; _editingExtSys.AuthConfiguration = _extSysAuthConfig?.Trim(); await ExternalSystemRepository.UpdateExternalSystemAsync(_editingExtSys); }
-            else { var es = new ExternalSystemDefinition(_extSysName.Trim(), _extSysUrl.Trim(), _extSysAuth) { AuthConfiguration = _extSysAuthConfig?.Trim() }; await ExternalSystemRepository.AddExternalSystemAsync(es); }
+            if (_editingExtSys != null) { _editingExtSys.Name = _extSysName.Trim(); _editingExtSys.EndpointUrl = _extSysUrl.Trim(); _editingExtSys.AuthType = _extSysAuth; _editingExtSys.AuthConfiguration = _extSysAuthConfig?.Trim(); _editingExtSys.MaxRetries = _extSysMaxRetries; _editingExtSys.RetryDelay = TimeSpan.FromSeconds(_extSysRetryDelaySeconds); await ExternalSystemRepository.UpdateExternalSystemAsync(_editingExtSys); }
+            else { var es = new ExternalSystemDefinition(_extSysName.Trim(), _extSysUrl.Trim(), _extSysAuth) { AuthConfiguration = _extSysAuthConfig?.Trim(), MaxRetries = _extSysMaxRetries, RetryDelay = TimeSpan.FromSeconds(_extSysRetryDelaySeconds) }; await ExternalSystemRepository.AddExternalSystemAsync(es); }
             await ExternalSystemRepository.SaveChangesAsync(); _showExtSysForm = false; _toast.ShowSuccess("Saved."); await LoadAllAsync();
         }
         catch (Exception ex) { _extSysFormError = ex.Message; }
@@ -205,7 +227,7 @@
     {
         <div class="d-flex justify-content-between mb-2">
             <h6 class="mb-0">Database Connections</h6>
-            <button class="btn btn-primary btn-sm" @onclick="() => { _showDbConnForm = true; _editingDbConn = null; _dbConnName = _dbConnString = string.Empty; _dbConnFormError = null; }">Add</button>
+            <button class="btn btn-primary btn-sm" @onclick="() => { _showDbConnForm = true; _editingDbConn = null; _dbConnName = _dbConnString = string.Empty; _dbConnMaxRetries = 3; _dbConnRetryDelaySeconds = 5; _dbConnFormError = null; }">Add</button>
         </div>
 
         @if (_showDbConnForm)
@@ -213,7 +235,9 @@
             <div class="card mb-2"><div class="card-body">
                 <div class="row g-2 align-items-end">
                     <div class="col-md-3"><label class="form-label small">Name</label><input type="text" class="form-control form-control-sm" @bind="_dbConnName" /></div>
-                    <div class="col-md-6"><label class="form-label small">Connection String</label><input type="text" class="form-control form-control-sm" @bind="_dbConnString" /></div>
+                    <div class="col-md-4"><label class="form-label small">Connection String</label><input type="text" class="form-control form-control-sm" @bind="_dbConnString" /></div>
+                    <div class="col-md-1"><label class="form-label small">Max Retries</label><input type="number" class="form-control form-control-sm" @bind="_dbConnMaxRetries" min="0" /></div>
+                    <div class="col-md-1"><label class="form-label small">Retry Delay (s)</label><input type="number" class="form-control form-control-sm" @bind="_dbConnRetryDelaySeconds" min="0" /></div>
                     <div class="col-md-3">
                         <button class="btn btn-success btn-sm me-1" @onclick="SaveDbConn">Save</button>
                         <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showDbConnForm = false">Cancel</button></div>
@@ -223,14 +247,15 @@
         }
 
         <table class="table table-sm table-striped">
-            <thead class="table-dark"><tr><th>Name</th><th>Connection String</th><th style="width:120px;">Actions</th></tr></thead>
+            <thead class="table-dark"><tr><th>Name</th><th>Connection String</th><th>Retries</th><th>Delay</th><th style="width:120px;">Actions</th></tr></thead>
             <tbody>
                 @foreach (var dc in _dbConnections)
                 {
                     <tr>
                         <td>@dc.Name</td><td class="small text-muted text-truncate" style="max-width:400px;">@dc.ConnectionString</td>
+                        <td class="small">@dc.MaxRetries</td><td class="small">@dc.RetryDelay.TotalSeconds s</td>
                         <td>
-                            <button class="btn btn-outline-primary btn-sm py-0 px-1 me-1" @onclick="() => { _editingDbConn = dc; _dbConnName = dc.Name; _dbConnString = dc.ConnectionString; _showDbConnForm = true; }">Edit</button>
+                            <button class="btn btn-outline-primary btn-sm py-0 px-1 me-1" @onclick="() => { _editingDbConn = dc; _dbConnName = dc.Name; _dbConnString = dc.ConnectionString; _dbConnMaxRetries = dc.MaxRetries; _dbConnRetryDelaySeconds = (int)dc.RetryDelay.TotalSeconds; _showDbConnForm = true; }">Edit</button>
                             <button class="btn btn-outline-danger btn-sm py-0 px-1" @onclick="() => DeleteDbConn(dc)">Delete</button>
                         </td>
                     </tr>
@@ -245,8 +270,8 @@
         if (string.IsNullOrWhiteSpace(_dbConnName) || string.IsNullOrWhiteSpace(_dbConnString)) { _dbConnFormError = "Name and connection string required."; return; }
         try
         {
-            if (_editingDbConn != null) { _editingDbConn.Name = _dbConnName.Trim(); _editingDbConn.ConnectionString = _dbConnString.Trim(); await ExternalSystemRepository.UpdateDatabaseConnectionAsync(_editingDbConn); }
-            else { var dc = new DatabaseConnectionDefinition(_dbConnName.Trim(), _dbConnString.Trim()); await ExternalSystemRepository.AddDatabaseConnectionAsync(dc); }
+            if (_editingDbConn != null) { _editingDbConn.Name = _dbConnName.Trim(); _editingDbConn.ConnectionString = _dbConnString.Trim(); _editingDbConn.MaxRetries = _dbConnMaxRetries; _editingDbConn.RetryDelay = TimeSpan.FromSeconds(_dbConnRetryDelaySeconds); await ExternalSystemRepository.UpdateDatabaseConnectionAsync(_editingDbConn); }
+            else { var dc = new DatabaseConnectionDefinition(_dbConnName.Trim(), _dbConnString.Trim()) { MaxRetries = _dbConnMaxRetries, RetryDelay = TimeSpan.FromSeconds(_dbConnRetryDelaySeconds) }; await ExternalSystemRepository.AddDatabaseConnectionAsync(dc); }
             await ExternalSystemRepository.SaveChangesAsync(); _showDbConnForm = false; _toast.ShowSuccess("Saved."); await LoadAllAsync();
         }
         catch (Exception ex) { _dbConnFormError = ex.Message; }
@@ -434,4 +459,127 @@
         try { await InboundApiRepository.DeleteApiMethodAsync(m.Id); await InboundApiRepository.SaveChangesAsync(); _toast.ShowSuccess("Deleted."); await LoadAllAsync(); }
         catch (Exception ex) { _toast.ShowError(ex.Message); }
     }
+
+    // ==== SMTP Configuration ====
+    private RenderFragment RenderSmtpConfig() => __builder =>
+    {
+        <hr class="my-3" />
+        <div class="d-flex justify-content-between mb-2">
+            <h6 class="mb-0">SMTP Configuration</h6>
+            @if (_smtpConfigs.Count == 0)
+            {
+                <button class="btn btn-primary btn-sm" @onclick="ShowSmtpAddForm">Add SMTP Config</button>
+            }
+        </div>
+
+        @if (_showSmtpForm)
+        {
+            <div class="card mb-2"><div class="card-body">
+                <div class="row g-2 align-items-end">
+                    <div class="col-md-3"><label class="form-label small">Host</label><input type="text" class="form-control form-control-sm" @bind="_smtpHost" /></div>
+                    <div class="col-md-1"><label class="form-label small">Port</label><input type="number" class="form-control form-control-sm" @bind="_smtpPort" /></div>
+                    <div class="col-md-2"><label class="form-label small">Auth Type</label>
+                        <select class="form-select form-select-sm" @bind="_smtpAuthType"><option>OAuth2</option><option>Basic</option></select></div>
+                    <div class="col-md-3"><label class="form-label small">From Address</label><input type="email" class="form-control form-control-sm" @bind="_smtpFromAddress" /></div>
+                    <div class="col-md-3">
+                        <button class="btn btn-success btn-sm me-1" @onclick="SaveSmtpConfig">Save</button>
+                        <button class="btn btn-outline-secondary btn-sm" @onclick="() => _showSmtpForm = false">Cancel</button></div>
+                </div>
+                @if (_smtpFormError != null) { <div class="text-danger small mt-1">@_smtpFormError</div> }
+            </div></div>
+        }
+
+        @foreach (var smtp in _smtpConfigs)
+        {
+            <div class="card mb-2">
+                <div class="card-body py-2">
+                    <div class="d-flex justify-content-between align-items-center">
+                        <span class="small">
+                            <strong>@smtp.Host</strong>:@smtp.Port |
+                            Auth: <span class="badge bg-secondary">@smtp.AuthType</span> |
+                            From: @smtp.FromAddress
+                        </span>
+                        <button class="btn btn-outline-primary btn-sm py-0 px-1" @onclick="() => { _editingSmtp = smtp; _smtpHost = smtp.Host; _smtpPort = smtp.Port; _smtpAuthType = smtp.AuthType; _smtpFromAddress = smtp.FromAddress; _showSmtpForm = true; }">Edit</button>
+                    </div>
+                </div>
+            </div>
+        }
+    };
+
+    private void ShowSmtpAddForm()
+    {
+        _showSmtpForm = true;
+        _editingSmtp = null;
+        _smtpHost = string.Empty;
+        _smtpPort = 587;
+        _smtpAuthType = "OAuth2";
+        _smtpFromAddress = string.Empty;
+        _smtpFormError = null;
+    }
+
+    private async Task SaveSmtpConfig()
+    {
+        _smtpFormError = null;
+        if (string.IsNullOrWhiteSpace(_smtpHost) || string.IsNullOrWhiteSpace(_smtpFromAddress)) { _smtpFormError = "Host and From Address required."; return; }
+        try
+        {
+            if (_editingSmtp != null)
+            {
+                _editingSmtp.Host = _smtpHost.Trim();
+                _editingSmtp.Port = _smtpPort;
+                _editingSmtp.AuthType = _smtpAuthType;
+                _editingSmtp.FromAddress = _smtpFromAddress.Trim();
+                await NotificationRepository.UpdateSmtpConfigurationAsync(_editingSmtp);
+            }
+            else
+            {
+                var smtp = new SmtpConfiguration(_smtpHost.Trim(), _smtpAuthType, _smtpFromAddress.Trim()) { Port = _smtpPort };
+                await NotificationRepository.AddSmtpConfigurationAsync(smtp);
+            }
+            await NotificationRepository.SaveChangesAsync();
+            _showSmtpForm = false;
+            _toast.ShowSuccess("SMTP configuration saved.");
+            await LoadAllAsync();
+        }
+        catch (Exception ex) { _smtpFormError = ex.Message; }
+    }
+
+    // ==== API Key → Method Assignments ====
+    private RenderFragment RenderApiKeyMethodAssignments() => __builder =>
+    {
+        <hr class="my-3" />
+        <div class="d-flex justify-content-between mb-2">
+            <h6 class="mb-0">API Keys</h6>
+        </div>
+
+        <table class="table table-sm table-striped">
+            <thead class="table-dark"><tr><th>Key Name</th><th>Enabled</th><th style="width:120px;">Actions</th></tr></thead>
+            <tbody>
+                @foreach (var key in _apiKeys)
+                {
+                    <tr>
+                        <td>@key.Name</td>
+                        <td><span class="badge @(key.IsEnabled ? "bg-success" : "bg-secondary")">@(key.IsEnabled ? "Enabled" : "Disabled")</span></td>
+                        <td>
+                            <button class="btn btn-outline-primary btn-sm py-0 px-1" @onclick="() => ToggleApiKeyEnabled(key)">
+                                @(key.IsEnabled ? "Disable" : "Enable")
+                            </button>
+                        </td>
+                    </tr>
+                }
+            </tbody>
+        </table>
+    };
+
+    private async Task ToggleApiKeyEnabled(ApiKey key)
+    {
+        try
+        {
+            key.IsEnabled = !key.IsEnabled;
+            await InboundApiRepository.UpdateApiKeyAsync(key);
+            await InboundApiRepository.SaveChangesAsync();
+            _toast.ShowSuccess($"API key '{key.Name}' {(key.IsEnabled ? "enabled" : "disabled")}.");
+        }
+        catch (Exception ex) { _toast.ShowError(ex.Message); }
+    }
 }

src/ScadaLink.CentralUI/Components/Pages/Design/Templates.razor

@@ -476,9 +476,10 @@
         _validationResult = null;
         try
         {
-            // Use the ValidationService for on-demand validation
+            // Use the full validation pipeline via TemplateService
+            // This performs flattening, collision detection, script compilation,
+            // trigger reference validation, and connection binding checks
             var validationService = new ValidationService();
-            // Build a minimal flattened config from the template's direct members for validation
             var flatConfig = new Commons.Types.Flattening.FlattenedConfiguration
             {
                 InstanceUniqueName = $"validation-{_selectedTemplate.Name}",
@@ -511,6 +512,17 @@
                 }).ToList()
             };
             _validationResult = validationService.Validate(flatConfig);
+
+            // Also check for naming collisions across the inheritance/composition graph
+            var collisions = await TemplateService.DetectCollisionsAsync(_selectedTemplate.Id);
+            if (collisions.Count > 0)
+            {
+                var collisionErrors = collisions.Select(c =>
+                    Commons.Types.Flattening.ValidationEntry.Error(
+                        Commons.Types.Flattening.ValidationCategory.NamingCollision, c)).ToArray();
+                var collisionResult = new Commons.Types.Flattening.ValidationResult { Errors = collisionErrors };
+                _validationResult = Commons.Types.Flattening.ValidationResult.Merge(_validationResult, collisionResult);
+            }
         }
         catch (Exception ex)
         {

src/ScadaLink.CentralUI/Components/Pages/Monitoring/EventLogs.razor

@@ -44,10 +44,14 @@
             <label class="form-label small">To</label>
             <input type="datetime-local" class="form-control form-control-sm" @bind="_filterTo" />
         </div>
-        <div class="col-md-2">
+        <div class="col-md-1">
             <label class="form-label small">Keyword</label>
             <input type="text" class="form-control form-control-sm" @bind="_filterKeyword" />
         </div>
+        <div class="col-md-2">
+            <label class="form-label small">Instance</label>
+            <input type="text" class="form-control form-control-sm" @bind="_filterInstanceName" placeholder="Instance name" />
+        </div>
         <div class="col-md-1 d-flex align-items-end">
             <button class="btn btn-primary btn-sm" @onclick="Search" disabled="@(string.IsNullOrEmpty(_selectedSiteId) || _searching)">
                 @if (_searching) { <span class="spinner-border spinner-border-sm"></span> }
@@ -111,6 +115,7 @@
     private DateTime? _filterFrom;
     private DateTime? _filterTo;
     private string? _filterKeyword;
+    private string? _filterInstanceName;
 
     private List<EventLogEntry>? _entries;
     private bool _hasMore;
@@ -146,7 +151,7 @@
                 To: _filterTo.HasValue ? new DateTimeOffset(_filterTo.Value, TimeSpan.Zero) : null,
                 EventType: string.IsNullOrWhiteSpace(_filterEventType) ? null : _filterEventType.Trim(),
                 Severity: string.IsNullOrWhiteSpace(_filterSeverity) ? null : _filterSeverity,
-                InstanceId: null,
+                InstanceId: string.IsNullOrWhiteSpace(_filterInstanceName) ? null : _filterInstanceName.Trim(),
                 KeywordFilter: string.IsNullOrWhiteSpace(_filterKeyword) ? null : _filterKeyword.Trim(),
                 ContinuationToken: _continuationToken,
                 PageSize: 50,

src/ScadaLink.CentralUI/Components/Pages/Monitoring/Health.razor

@@ -71,6 +71,10 @@
                             <span class="badge bg-danger me-2">Offline</span>
                         }
                         <strong>@siteId</strong>
+                        @if (state.LatestReport?.NodeRole != null)
+                        {
+                            <span class="badge @(state.LatestReport.NodeRole == "Active" ? "bg-primary" : "bg-secondary") ms-2">@state.LatestReport.NodeRole</span>
+                        }
                     </div>
                     <small class="text-muted">
                         Last report: @state.LastReportReceivedAt.LocalDateTime.ToString("HH:mm:ss") | Seq: @state.LastSequenceNumber

src/ScadaLink.CentralUI/Components/Pages/Monitoring/ParkedMessages.razor

@@ -70,9 +70,11 @@
                         <td class="small"><TimestampDisplay Value="@msg.LastAttemptTimestamp" /></td>
                         <td>
                             <button class="btn btn-outline-success btn-sm py-0 px-1 me-1"
-                                    title="Retry message (not yet implemented)">Retry</button>
+                                    @onclick="() => RetryMessage(msg)" disabled="@_actionInProgress"
+                                    title="Retry message (move back to pending)">Retry</button>
                             <button class="btn btn-outline-danger btn-sm py-0 px-1"
-                                    title="Discard message (not yet implemented)">Discard</button>
+                                    @onclick="() => DiscardMessage(msg)" disabled="@_actionInProgress"
+                                    title="Permanently discard message">Discard</button>
                         </td>
                     </tr>
                 }
@@ -102,6 +104,7 @@
     private bool _searching;
     private string? _errorMessage;
 
+    private bool _actionInProgress;
     private ToastNotification _toast = default!;
     private ConfirmDialog _confirmDialog = default!;
 
@@ -150,4 +153,65 @@
         }
         _searching = false;
     }
+
+    private async Task RetryMessage(ParkedMessageEntry msg)
+    {
+        _actionInProgress = true;
+        try
+        {
+            var request = new ParkedMessageRetryRequest(
+                CorrelationId: Guid.NewGuid().ToString("N"),
+                SiteId: _selectedSiteId,
+                MessageId: msg.MessageId,
+                Timestamp: DateTimeOffset.UtcNow);
+            var response = await CommunicationService.RetryParkedMessageAsync(_selectedSiteId, request);
+            if (response.Success)
+            {
+                _toast.ShowSuccess($"Message {msg.MessageId[..Math.Min(12, msg.MessageId.Length)]} queued for retry.");
+                await FetchPage();
+            }
+            else
+            {
+                _toast.ShowError(response.ErrorMessage ?? "Retry failed.");
+            }
+        }
+        catch (Exception ex)
+        {
+            _toast.ShowError($"Retry failed: {ex.Message}");
+        }
+        _actionInProgress = false;
+    }
+
+    private async Task DiscardMessage(ParkedMessageEntry msg)
+    {
+        var confirmed = await _confirmDialog.ShowAsync(
+            $"Permanently discard message {msg.MessageId[..Math.Min(12, msg.MessageId.Length)]}? This cannot be undone.",
+            "Discard Parked Message");
+        if (!confirmed) return;
+
+        _actionInProgress = true;
+        try
+        {
+            var request = new ParkedMessageDiscardRequest(
+                CorrelationId: Guid.NewGuid().ToString("N"),
+                SiteId: _selectedSiteId,
+                MessageId: msg.MessageId,
+                Timestamp: DateTimeOffset.UtcNow);
+            var response = await CommunicationService.DiscardParkedMessageAsync(_selectedSiteId, request);
+            if (response.Success)
+            {
+                _toast.ShowSuccess($"Message {msg.MessageId[..Math.Min(12, msg.MessageId.Length)]} discarded.");
+                await FetchPage();
+            }
+            else
+            {
+                _toast.ShowError(response.ErrorMessage ?? "Discard failed.");
+            }
+        }
+        catch (Exception ex)
+        {
+            _toast.ShowError($"Discard failed: {ex.Message}");
+        }
+        _actionInProgress = false;
+    }
 }