diff --git a/static/admin/js/background-tasks.js b/static/admin/js/background-tasks.js
index bc7fd04a..4834b449 100644
--- a/static/admin/js/background-tasks.js
+++ b/static/admin/js/background-tasks.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 /**
  * Background Tasks Monitoring Component
  * Manages the background tasks monitoring page
@@ -37,18 +38,26 @@ function backgroundTasks() {
         runningTasks: [],
 
         async init() {
-            backgroundTasksLog.info('Initializing background tasks monitor');
-            await this.loadStats();
-            await this.loadTasks();
-            await this.loadRunningTasks();
+            // Guard against multiple initialization
+            if (window._adminBackgroundTasksInitialized) return;
+            window._adminBackgroundTasksInitialized = true;
 
-            // Poll for updates every 5 seconds
-            this.pollInterval = setInterval(() => {
-                this.loadRunningTasks();
-                if (this.runningTasks.length > 0) {
-                    this.loadStats();
-                }
-            }, 5000);
+            try {
+                backgroundTasksLog.info('Initializing background tasks monitor');
+                await this.loadStats();
+                await this.loadTasks();
+                await this.loadRunningTasks();
+
+                // Poll for updates every 5 seconds
+                this.pollInterval = setInterval(() => {
+                    this.loadRunningTasks();
+                    if (this.runningTasks.length > 0) {
+                        this.loadStats();
+                    }
+                }, 5000);
+            } catch (error) {
+                backgroundTasksLog.error('Failed to initialize background tasks:', error);
+            }
         },
 
         destroy() {
diff --git a/static/admin/js/billing-history.js b/static/admin/js/billing-history.js
index 2a46ed60..2043703a 100644
--- a/static/admin/js/billing-history.js
+++ b/static/admin/js/billing-history.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/billing-history.js
 // noqa: JS-003 - Uses ...baseData which is data() with safety check
 
diff --git a/static/admin/js/code-quality-dashboard.js b/static/admin/js/code-quality-dashboard.js
index bfe384bb..04f0cd1a 100644
--- a/static/admin/js/code-quality-dashboard.js
+++ b/static/admin/js/code-quality-dashboard.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 /**
  * Code Quality Dashboard Component
  * Manages the unified code quality dashboard page
@@ -49,20 +50,28 @@ function codeQualityDashboard() {
         },
 
         async init() {
-            // Check URL for validator_type parameter
-            const urlParams = new URLSearchParams(window.location.search);
-            const urlValidator = urlParams.get('validator_type');
-            if (urlValidator && this.validatorTypes.includes(urlValidator)) {
-                this.selectedValidator = urlValidator;
-            } else {
-                // Ensure 'all' is explicitly set as default
-                this.selectedValidator = 'all';
+            // Guard against multiple initialization
+            if (window._adminCodeQualityDashboardInitialized) return;
+            window._adminCodeQualityDashboardInitialized = true;
+
+            try {
+                // Check URL for validator_type parameter
+                const urlParams = new URLSearchParams(window.location.search);
+                const urlValidator = urlParams.get('validator_type');
+                if (urlValidator && this.validatorTypes.includes(urlValidator)) {
+                    this.selectedValidator = urlValidator;
+                } else {
+                    // Ensure 'all' is explicitly set as default
+                    this.selectedValidator = 'all';
+                }
+
+                await this.loadStats();
+
+                // Check for any running scans on page load
+                await this.checkRunningScans();
+            } catch (error) {
+                codeQualityLog.error('Failed to initialize code quality dashboard:', error);
             }
-
-            await this.loadStats();
-
-            // Check for any running scans on page load
-            await this.checkRunningScans();
         },
 
         async checkRunningScans() {
diff --git a/static/admin/js/code-quality-violations.js b/static/admin/js/code-quality-violations.js
index 5c0da608..5a7f1884 100644
--- a/static/admin/js/code-quality-violations.js
+++ b/static/admin/js/code-quality-violations.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 /**
  * Code Quality Violations List Component
  * Manages the violations list page with filtering and pagination
diff --git a/static/admin/js/companies.js b/static/admin/js/companies.js
index d252c8bd..8f200d10 100644
--- a/static/admin/js/companies.js
+++ b/static/admin/js/companies.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/companies.js
 
 // ✅ Use centralized logger
diff --git a/static/admin/js/company-detail.js b/static/admin/js/company-detail.js
index a894255d..dd1b1428 100644
--- a/static/admin/js/company-detail.js
+++ b/static/admin/js/company-detail.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/company-detail.js
 
 // Create custom logger for company detail
diff --git a/static/admin/js/company-edit.js b/static/admin/js/company-edit.js
index 424af655..5fa03614 100644
--- a/static/admin/js/company-edit.js
+++ b/static/admin/js/company-edit.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/company-edit.js
 
 // Create custom logger for company edit
diff --git a/static/admin/js/content-page-edit.js b/static/admin/js/content-page-edit.js
index d12d6ce6..34ae3898 100644
--- a/static/admin/js/content-page-edit.js
+++ b/static/admin/js/content-page-edit.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/content-page-edit.js
 
 // Use centralized logger
diff --git a/static/admin/js/content-pages.js b/static/admin/js/content-pages.js
index c4d9a132..f2669d08 100644
--- a/static/admin/js/content-pages.js
+++ b/static/admin/js/content-pages.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/content-pages.js
 
 // Use centralized logger
diff --git a/static/admin/js/customers.js b/static/admin/js/customers.js
index 6da443e0..15a56429 100644
--- a/static/admin/js/customers.js
+++ b/static/admin/js/customers.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/customers.js
 /**
  * Admin customer management page logic
@@ -368,7 +369,7 @@ function adminCustomers() {
                 customersLog.info(response.message);
             } catch (error) {
                 customersLog.error('Failed to toggle status:', error);
-                alert(error.message || 'Failed to toggle customer status');
+                Utils.showToast(error.message || 'Failed to toggle customer status', 'error');
             }
         },
 
diff --git a/static/admin/js/dashboard.js b/static/admin/js/dashboard.js
index 3658a6cf..e0c5a79e 100644
--- a/static/admin/js/dashboard.js
+++ b/static/admin/js/dashboard.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/dashboard.js
 
 // ✅ Use centralized logger - ONE LINE!
@@ -24,6 +25,13 @@ function adminDashboard() {
          * Initialize dashboard
          */
         async init() {
+            // Guard against multiple initialization
+            if (window._dashboardInitialized) {
+                dashLog.warn('Dashboard already initialized, skipping...');
+                return;
+            }
+            window._dashboardInitialized = true;
+
             dashLog.info('=== DASHBOARD INITIALIZING ===');
             dashLog.debug('Current URL:', window.location.href);
             dashLog.debug('Current pathname:', window.location.pathname);
@@ -33,13 +41,6 @@ function adminDashboard() {
             if (token) {
                 dashLog.debug('Token preview:', token.substring(0, 20) + '...');
             }
-
-            // Prevent multiple initializations
-            if (window._dashboardInitialized) {
-                dashLog.warn('Dashboard already initialized, skipping...');
-                return;
-            }
-            window._dashboardInitialized = true;
             dashLog.debug('Dashboard initialization flag set');
 
             const startTime = performance.now();
diff --git a/static/admin/js/imports.js b/static/admin/js/imports.js
index 6f4a0ab0..67a56d8a 100644
--- a/static/admin/js/imports.js
+++ b/static/admin/js/imports.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/imports.js
 /**
  * Admin platform monitoring - all import jobs
diff --git a/static/admin/js/inventory.js b/static/admin/js/inventory.js
index b1d8a767..42d940db 100644
--- a/static/admin/js/inventory.js
+++ b/static/admin/js/inventory.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/inventory.js
 /**
  * Admin inventory management page logic
@@ -553,20 +554,7 @@ function adminInventory() {
                 formData.append('warehouse', this.importForm.warehouse || 'strassen');
                 formData.append('clear_existing', this.importForm.clear_existing);
 
-                const response = await fetch('/api/v1/admin/inventory/import', {
-                    method: 'POST',
-                    body: formData,
-                    headers: {
-                        'Authorization': `Bearer ${localStorage.getItem('access_token') || ''}`
-                    }
-                });
-
-                if (!response.ok) {
-                    const errorData = await response.json();
-                    throw new Error(errorData.detail || 'Import failed');
-                }
-
-                this.importResult = await response.json();
+                this.importResult = await apiClient.postFormData('/admin/inventory/import', formData);
 
                 if (this.importResult.success) {
                     adminInventoryLog.info('Import successful:', this.importResult);
diff --git a/static/admin/js/login.js b/static/admin/js/login.js
index bfb842e5..fd32247f 100644
--- a/static/admin/js/login.js
+++ b/static/admin/js/login.js
@@ -19,6 +19,10 @@ function adminLogin() {
         errors: {},
 
         init() {
+            // Guard against multiple initialization
+            if (window._adminLoginInitialized) return;
+            window._adminLoginInitialized = true;
+
             loginLog.info('=== LOGIN PAGE INITIALIZING ===');
             loginLog.debug('Current pathname:', window.location.pathname);
             loginLog.debug('Current URL:', window.location.href);
diff --git a/static/admin/js/logs.js b/static/admin/js/logs.js
index 08d50a61..ddeb5631 100644
--- a/static/admin/js/logs.js
+++ b/static/admin/js/logs.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/logs.js
 // noqa: JS-003 - Uses ...baseData which is data() with safety check
 
diff --git a/static/admin/js/marketplace-letzshop.js b/static/admin/js/marketplace-letzshop.js
index 1e9a86a0..97f70dc9 100644
--- a/static/admin/js/marketplace-letzshop.js
+++ b/static/admin/js/marketplace-letzshop.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/marketplace-letzshop.js
 /**
  * Admin marketplace Letzshop management page logic
diff --git a/static/admin/js/marketplace-product-detail.js b/static/admin/js/marketplace-product-detail.js
index 858db912..7c8f86d6 100644
--- a/static/admin/js/marketplace-product-detail.js
+++ b/static/admin/js/marketplace-product-detail.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/marketplace-product-detail.js
 /**
  * Admin marketplace product detail page logic
diff --git a/static/admin/js/marketplace-products.js b/static/admin/js/marketplace-products.js
index 3ca1f71e..2c6a91e0 100644
--- a/static/admin/js/marketplace-products.js
+++ b/static/admin/js/marketplace-products.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/marketplace-products.js
 /**
  * Admin marketplace products page logic
diff --git a/static/admin/js/marketplace.js b/static/admin/js/marketplace.js
index bb6995f9..7934de98 100644
--- a/static/admin/js/marketplace.js
+++ b/static/admin/js/marketplace.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/marketplace.js
 /**
  * Admin marketplace import page logic
diff --git a/static/admin/js/messages.js b/static/admin/js/messages.js
index 4591649e..539fead4 100644
--- a/static/admin/js/messages.js
+++ b/static/admin/js/messages.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 /**
  * Admin Messages Page
  *
@@ -66,17 +67,25 @@ function adminMessages(initialConversationId = null) {
          * Initialize component
          */
         async init() {
-            messagesLog.debug('Initializing messages page');
-            await this.loadConversations();
+            // Guard against multiple initialization
+            if (window._adminMessagesInitialized) return;
+            window._adminMessagesInitialized = true;
 
-            if (this.selectedConversationId) {
-                await this.loadConversation(this.selectedConversationId);
+            try {
+                messagesLog.debug('Initializing messages page');
+                await this.loadConversations();
+
+                if (this.selectedConversationId) {
+                    await this.loadConversation(this.selectedConversationId);
+                }
+
+                // Start polling for new messages
+                this.startPolling();
+            } catch (error) {
+                messagesLog.error('Failed to initialize messages page:', error);
+            } finally {
+                this.loading = false;
             }
-
-            this.loading = false;
-
-            // Start polling for new messages
-            this.startPolling();
         },
 
         /**
@@ -132,7 +141,7 @@ function adminMessages(initialConversationId = null) {
                 messagesLog.debug(`Loaded ${this.conversations.length} conversations`);
             } catch (error) {
                 messagesLog.error('Failed to load conversations:', error);
-                window.showToast?.('Failed to load conversations', 'error');
+                Utils.showToast('Failed to load conversations', 'error');
             } finally {
                 this.loadingConversations = false;
             }
@@ -188,7 +197,7 @@ function adminMessages(initialConversationId = null) {
                 this.scrollToBottom();
             } catch (error) {
                 messagesLog.error('Failed to load conversation:', error);
-                window.showToast?.('Failed to load conversation', 'error');
+                Utils.showToast('Failed to load conversation', 'error');
             } finally {
                 this.loadingMessages = false;
             }
@@ -256,20 +265,7 @@ function adminMessages(initialConversationId = null) {
                     formData.append('files', file);
                 }
 
-                const response = await fetch(`/api/v1/admin/messages/${this.selectedConversationId}/messages`, {
-                    method: 'POST',
-                    body: formData,
-                    headers: {
-                        'Authorization': `Bearer ${window.getAuthToken?.() || ''}`
-                    }
-                });
-
-                if (!response.ok) {
-                    const error = await response.json();
-                    throw new Error(error.detail || 'Failed to send message');
-                }
-
-                const message = await response.json();
+                const message = await apiClient.postFormData(`/admin/messages/${this.selectedConversationId}/messages`, formData);
 
                 // Add to messages
                 if (this.selectedConversation) {
@@ -291,7 +287,7 @@ function adminMessages(initialConversationId = null) {
                 messagesLog.debug(`Sent message ${message.id}`);
             } catch (error) {
                 messagesLog.error('Failed to send message:', error);
-                window.showToast?.(error.message || 'Failed to send message', 'error');
+                Utils.showToast(error.message || 'Failed to send message', 'error');
             } finally {
                 this.sendingMessage = false;
             }
@@ -320,10 +316,10 @@ function adminMessages(initialConversationId = null) {
                     conv.is_closed = true;
                 }
 
-                window.showToast?.('Conversation closed', 'success');
+                Utils.showToast('Conversation closed', 'success');
             } catch (error) {
                 messagesLog.error('Failed to close conversation:', error);
-                window.showToast?.('Failed to close conversation', 'error');
+                Utils.showToast('Failed to close conversation', 'error');
             }
         },
 
@@ -344,10 +340,10 @@ function adminMessages(initialConversationId = null) {
                     conv.is_closed = false;
                 }
 
-                window.showToast?.('Conversation reopened', 'success');
+                Utils.showToast('Conversation reopened', 'success');
             } catch (error) {
                 messagesLog.error('Failed to reopen conversation:', error);
-                window.showToast?.('Failed to reopen conversation', 'error');
+                Utils.showToast('Failed to reopen conversation', 'error');
             }
         },
 
@@ -371,7 +367,7 @@ function adminMessages(initialConversationId = null) {
                 messagesLog.debug(`Loaded ${this.recipients.length} recipients`);
             } catch (error) {
                 messagesLog.error('Failed to load recipients:', error);
-                window.showToast?.('Failed to load recipients', 'error');
+                Utils.showToast('Failed to load recipients', 'error');
             } finally {
                 this.loadingRecipients = false;
             }
@@ -420,10 +416,10 @@ function adminMessages(initialConversationId = null) {
                 await this.loadConversations();
                 await this.selectConversation(response.id);
 
-                window.showToast?.('Conversation created', 'success');
+                Utils.showToast('Conversation created', 'success');
             } catch (error) {
                 messagesLog.error('Failed to create conversation:', error);
-                window.showToast?.(error.message || 'Failed to create conversation', 'error');
+                Utils.showToast(error.message || 'Failed to create conversation', 'error');
             } finally {
                 this.creatingConversation = false;
             }
diff --git a/static/admin/js/notifications.js b/static/admin/js/notifications.js
index c651ed42..12e742da 100644
--- a/static/admin/js/notifications.js
+++ b/static/admin/js/notifications.js
@@ -71,12 +71,21 @@ function adminNotifications() {
          * Initialize component
          */
         async init() {
-            notificationsLog.debug('Initializing notifications page');
-            await Promise.all([
-                this.loadNotifications(),
-                this.loadAlertStats()
-            ]);
-            this.loading = false;
+            // Guard against multiple initialization
+            if (window._adminNotificationsInitialized) return;
+            window._adminNotificationsInitialized = true;
+
+            try {
+                notificationsLog.debug('Initializing notifications page');
+                await Promise.all([
+                    this.loadNotifications(),
+                    this.loadAlertStats()
+                ]);
+            } catch (error) {
+                notificationsLog.error('Failed to initialize notifications page:', error);
+            } finally {
+                this.loading = false;
+            }
         },
 
         // ============================================================================
@@ -105,7 +114,7 @@ function adminNotifications() {
                 notificationsLog.debug(`Loaded ${this.notifications.length} notifications`);
             } catch (error) {
                 notificationsLog.error('Failed to load notifications:', error);
-                window.showToast?.('Failed to load notifications', 'error');
+                Utils.showToast('Failed to load notifications', 'error');
             } finally {
                 this.loadingNotifications = false;
             }
@@ -122,10 +131,10 @@ function adminNotifications() {
                 notification.is_read = true;
                 this.stats.unread_count = Math.max(0, this.stats.unread_count - 1);
 
-                window.showToast?.('Notification marked as read', 'success');
+                Utils.showToast('Notification marked as read', 'success');
             } catch (error) {
                 notificationsLog.error('Failed to mark as read:', error);
-                window.showToast?.('Failed to mark notification as read', 'error');
+                Utils.showToast('Failed to mark notification as read', 'error');
             }
         },
 
@@ -140,10 +149,10 @@ function adminNotifications() {
                 this.notifications.forEach(n => n.is_read = true);
                 this.stats.unread_count = 0;
 
-                window.showToast?.('All notifications marked as read', 'success');
+                Utils.showToast('All notifications marked as read', 'success');
             } catch (error) {
                 notificationsLog.error('Failed to mark all as read:', error);
-                window.showToast?.('Failed to mark all as read', 'error');
+                Utils.showToast('Failed to mark all as read', 'error');
             }
         },
 
@@ -166,10 +175,10 @@ function adminNotifications() {
                     this.stats.unread_count = Math.max(0, this.stats.unread_count - 1);
                 }
 
-                window.showToast?.('Notification deleted', 'success');
+                Utils.showToast('Notification deleted', 'success');
             } catch (error) {
                 notificationsLog.error('Failed to delete notification:', error);
-                window.showToast?.('Failed to delete notification', 'error');
+                Utils.showToast('Failed to delete notification', 'error');
             }
         },
 
@@ -216,7 +225,7 @@ function adminNotifications() {
                 notificationsLog.debug(`Loaded ${this.alerts.length} alerts`);
             } catch (error) {
                 notificationsLog.error('Failed to load alerts:', error);
-                window.showToast?.('Failed to load alerts', 'error');
+                Utils.showToast('Failed to load alerts', 'error');
             } finally {
                 this.loadingAlerts = false;
             }
@@ -263,10 +272,10 @@ function adminNotifications() {
                 }
                 this.alertStats.resolved_today++;
 
-                window.showToast?.('Alert resolved successfully', 'success');
+                Utils.showToast('Alert resolved successfully', 'success');
             } catch (error) {
                 notificationsLog.error('Failed to resolve alert:', error);
-                window.showToast?.('Failed to resolve alert', 'error');
+                Utils.showToast('Failed to resolve alert', 'error');
             }
         },
 
diff --git a/static/admin/js/orders.js b/static/admin/js/orders.js
index a80f502d..7db416c7 100644
--- a/static/admin/js/orders.js
+++ b/static/admin/js/orders.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/orders.js
 /**
  * Admin orders management page logic
diff --git a/static/admin/js/platform-health.js b/static/admin/js/platform-health.js
index ae0f4830..b3b214fa 100644
--- a/static/admin/js/platform-health.js
+++ b/static/admin/js/platform-health.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/platform-health.js
 /**
  * Admin platform health monitoring page logic
diff --git a/static/admin/js/platform-homepage.js b/static/admin/js/platform-homepage.js
index 14c86f4e..353824ff 100644
--- a/static/admin/js/platform-homepage.js
+++ b/static/admin/js/platform-homepage.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/platform-homepage.js
 
 // Use centralized logger
diff --git a/static/admin/js/settings.js b/static/admin/js/settings.js
index 2d898151..2baea9b0 100644
--- a/static/admin/js/settings.js
+++ b/static/admin/js/settings.js
@@ -41,6 +41,10 @@ function adminSettings() {
         },
 
         async init() {
+            // Guard against multiple initialization
+            if (window._adminSettingsInitialized) return;
+            window._adminSettingsInitialized = true;
+
             try {
                 settingsLog.info('=== SETTINGS PAGE INITIALIZING ===');
                 await Promise.all([
diff --git a/static/admin/js/subscriptions.js b/static/admin/js/subscriptions.js
index df615a19..82ba2ec6 100644
--- a/static/admin/js/subscriptions.js
+++ b/static/admin/js/subscriptions.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/subscriptions.js
 // noqa: JS-003 - Uses ...baseData which is data() with safety check
 
diff --git a/static/admin/js/testing-dashboard.js b/static/admin/js/testing-dashboard.js
index d9e1888d..183f7881 100644
--- a/static/admin/js/testing-dashboard.js
+++ b/static/admin/js/testing-dashboard.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 /**
  * Testing Dashboard Component
  * Manages the pytest testing dashboard page
@@ -53,11 +54,19 @@ function testingDashboard() {
         runs: [],
 
         async init() {
-            testingDashboardLog.info('Initializing testing dashboard');
-            await this.loadStats();
-            await this.loadRuns();
-            // Check if there's a running test and resume polling
-            await this.checkForRunningTests();
+            // Guard against multiple initialization
+            if (window._adminTestingDashboardInitialized) return;
+            window._adminTestingDashboardInitialized = true;
+
+            try {
+                testingDashboardLog.info('Initializing testing dashboard');
+                await this.loadStats();
+                await this.loadRuns();
+                // Check if there's a running test and resume polling
+                await this.checkForRunningTests();
+            } catch (error) {
+                testingDashboardLog.error('Failed to initialize testing dashboard:', error);
+            }
         },
 
         async checkForRunningTests() {
diff --git a/static/admin/js/user-detail.js b/static/admin/js/user-detail.js
index 8a8f8a44..1f00b704 100644
--- a/static/admin/js/user-detail.js
+++ b/static/admin/js/user-detail.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/user-detail.js
 
 // Create custom logger for user detail
diff --git a/static/admin/js/user-edit.js b/static/admin/js/user-edit.js
index 9ab6fae5..a9b3d5ee 100644
--- a/static/admin/js/user-edit.js
+++ b/static/admin/js/user-edit.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/user-edit.js
 
 // Create custom logger for user edit
diff --git a/static/admin/js/users.js b/static/admin/js/users.js
index db8a5e19..96b521d7 100644
--- a/static/admin/js/users.js
+++ b/static/admin/js/users.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/users.js
 
 // ✅ Use centralized logger - ONE LINE!
diff --git a/static/admin/js/vendor-create.js b/static/admin/js/vendor-create.js
index 61d30ad1..63c0a685 100644
--- a/static/admin/js/vendor-create.js
+++ b/static/admin/js/vendor-create.js
@@ -43,8 +43,16 @@ function adminVendorCreate() {
 
         // Initialize
         async init() {
-            vendorCreateLog.info('Initializing vendor create page');
-            await this.loadCompanies();
+            // Guard against multiple initialization
+            if (window._adminVendorCreateInitialized) return;
+            window._adminVendorCreateInitialized = true;
+
+            try {
+                vendorCreateLog.info('Initializing vendor create page');
+                await this.loadCompanies();
+            } catch (error) {
+                vendorCreateLog.error('Failed to initialize vendor create:', error);
+            }
         },
 
         // Load companies for dropdown
diff --git a/static/admin/js/vendor-detail.js b/static/admin/js/vendor-detail.js
index bf896091..83823611 100644
--- a/static/admin/js/vendor-detail.js
+++ b/static/admin/js/vendor-detail.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/vendor-detail.js
 
 // ✅ Use centralized logger - ONE LINE!
diff --git a/static/admin/js/vendor-edit.js b/static/admin/js/vendor-edit.js
index d5c2d352..c4b9ed6c 100644
--- a/static/admin/js/vendor-edit.js
+++ b/static/admin/js/vendor-edit.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/vendor-edit.js
 
 // ✅ Use centralized logger - ONE LINE!
diff --git a/static/admin/js/vendor-products.js b/static/admin/js/vendor-products.js
index ac9a0dfc..fd6284f0 100644
--- a/static/admin/js/vendor-products.js
+++ b/static/admin/js/vendor-products.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/vendor-products.js
 /**
  * Admin vendor products page logic
diff --git a/static/admin/js/vendor-theme.js b/static/admin/js/vendor-theme.js
index ab896793..45c6ba87 100644
--- a/static/admin/js/vendor-theme.js
+++ b/static/admin/js/vendor-theme.js
@@ -78,6 +78,10 @@ function adminVendorTheme() {
         // ====================================================================
 
         async init() {
+            // Guard against multiple initialization
+            if (window._adminVendorThemeInitialized) return;
+            window._adminVendorThemeInitialized = true;
+
             themeLog.info('Initializing vendor theme editor');
 
             // Start performance timer
diff --git a/static/admin/js/vendor-themes.js b/static/admin/js/vendor-themes.js
index 3428f974..834bbf89 100644
--- a/static/admin/js/vendor-themes.js
+++ b/static/admin/js/vendor-themes.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/vendor-themes.js
 /**
  * Admin vendor themes selection page
diff --git a/static/admin/js/vendors.js b/static/admin/js/vendors.js
index 17e083f6..01238202 100644
--- a/static/admin/js/vendors.js
+++ b/static/admin/js/vendors.js
@@ -1,3 +1,4 @@
+// noqa: js-006 - async init pattern is safe, loadData has try/catch
 // static/admin/js/vendors.js
 
 // ✅ Use centralized logger - ONE LINE!
diff --git a/static/shared/js/api-client.js b/static/shared/js/api-client.js
index 62679e58..8ba1e677 100644
--- a/static/shared/js/api-client.js
+++ b/static/shared/js/api-client.js
@@ -232,6 +232,103 @@ class APIClient {
         });
     }
 
+    /**
+     * POST with FormData (for file uploads)
+     * Does not set Content-Type header - browser sets it with boundary
+     */
+    async postFormData(endpoint, formData) {
+        const url = `${this.baseURL}${endpoint}`;
+        apiLog.info(`POST (FormData) ${url}`);
+
+        const token = this.getToken();
+        const headers = {};
+        if (token) {
+            headers['Authorization'] = `Bearer ${token}`;
+        }
+
+        try {
+            const startTime = Date.now();
+            const response = await fetch(url, {
+                method: 'POST',
+                headers,
+                body: formData
+            });
+            const duration = Date.now() - startTime;
+
+            apiLog.info(`Response: ${response.status} ${response.statusText} (${duration}ms)`);
+
+            let data;
+            try {
+                data = await response.json();
+            } catch (parseError) {
+                apiLog.error('Failed to parse JSON response:', parseError);
+                throw new Error('Invalid JSON response from server');
+            }
+
+            if (response.status === 401) {
+                apiLog.warn('401 Unauthorized - Authentication failed');
+                this.clearTokens();
+                throw new Error(data.message || data.detail || 'Unauthorized');
+            }
+
+            if (!response.ok) {
+                throw new Error(data.detail || data.message || `Request failed with status ${response.status}`);
+            }
+
+            return data;
+        } catch (error) {
+            apiLog.error('FormData request error:', error.message);
+            throw error;
+        }
+    }
+
+    /**
+     * GET request that returns a Blob (for file downloads)
+     */
+    async getBlob(endpoint) {
+        const url = `${this.baseURL}${endpoint}`;
+        apiLog.info(`GET (Blob) ${url}`);
+
+        const token = this.getToken();
+        const headers = {};
+        if (token) {
+            headers['Authorization'] = `Bearer ${token}`;
+        }
+
+        try {
+            const startTime = Date.now();
+            const response = await fetch(url, {
+                method: 'GET',
+                headers
+            });
+            const duration = Date.now() - startTime;
+
+            apiLog.info(`Response: ${response.status} ${response.statusText} (${duration}ms)`);
+
+            if (response.status === 401) {
+                apiLog.warn('401 Unauthorized - Authentication failed');
+                this.clearTokens();
+                throw new Error('Unauthorized');
+            }
+
+            if (!response.ok) {
+                let errorMessage = `Request failed with status ${response.status}`;
+                try {
+                    const errorData = await response.json();
+                    errorMessage = errorData.detail || errorData.message || errorMessage;
+                } catch (e) {
+                    // Response wasn't JSON
+                }
+                throw new Error(errorMessage);
+            }
+
+            return response.blob();
+        } catch (error) {
+            apiLog.error('Blob request error:', error.message);
+            throw error;
+        }
+    }
+
     /**
      * Clear authentication tokens for current context only.
      *
diff --git a/static/shared/js/feature-store.js b/static/shared/js/feature-store.js
index 2eb5e82e..c155563e 100644
--- a/static/shared/js/feature-store.js
+++ b/static/shared/js/feature-store.js
@@ -53,8 +53,16 @@
          * Called automatically when Alpine starts
          */
         async init() {
-            log.debug('[FeatureStore] Initializing...');
-            await this.loadFeatures();
+            // Guard against multiple initialization
+            if (window._featureStoreInitialized) return;
+            window._featureStoreInitialized = true;
+
+            try {
+                log.debug('[FeatureStore] Initializing...');
+                await this.loadFeatures();
+            } catch (error) {
+                log.error('[FeatureStore] Failed to initialize:', error);
+            }
         },
 
         /**
@@ -186,10 +194,14 @@
          * Reload features (e.g., after tier change)
          */
         async reload() {
-            this.loaded = false;
-            this.features = [];
-            this.featuresMap = {};
-            await this.loadFeatures();
+            try {
+                this.loaded = false;
+                this.features = [];
+                this.featuresMap = {};
+                await this.loadFeatures();
+            } catch (error) {
+                log.error('[FeatureStore] Failed to reload:', error);
+            }
         }
     };
 
diff --git a/static/shared/js/upgrade-prompts.js b/static/shared/js/upgrade-prompts.js
index 9a18fab7..0a9804ca 100644
--- a/static/shared/js/upgrade-prompts.js
+++ b/static/shared/js/upgrade-prompts.js
@@ -344,8 +344,12 @@
          * Reload usage data
          */
         async reload() {
-            this.loaded = false;
-            await this.loadUsage();
+            try {
+                this.loaded = false;
+                await this.loadUsage();
+            } catch (error) {
+                log.error('[UpgradePrompts] Failed to reload:', error);
+            }
         }
     };
 
diff --git a/static/vendor/js/billing.js b/static/vendor/js/billing.js
index f752ee6d..a174396d 100644
--- a/static/vendor/js/billing.js
+++ b/static/vendor/js/billing.js
@@ -29,22 +29,30 @@ function vendorBilling() {
 
         // Initialize
         async init() {
-            // Check URL params for success/cancel
-            const params = new URLSearchParams(window.location.search);
-            if (params.get('success') === 'true') {
-                this.showSuccessMessage = true;
-                window.history.replaceState({}, document.title, window.location.pathname);
-            }
-            if (params.get('cancelled') === 'true') {
-                this.showCancelMessage = true;
-                window.history.replaceState({}, document.title, window.location.pathname);
-            }
-            if (params.get('addon_success') === 'true') {
-                this.showAddonSuccessMessage = true;
-                window.history.replaceState({}, document.title, window.location.pathname);
-            }
+            // Guard against multiple initialization
+            if (window._vendorBillingInitialized) return;
+            window._vendorBillingInitialized = true;
 
-            await this.loadData();
+            try {
+                // Check URL params for success/cancel
+                const params = new URLSearchParams(window.location.search);
+                if (params.get('success') === 'true') {
+                    this.showSuccessMessage = true;
+                    window.history.replaceState({}, document.title, window.location.pathname);
+                }
+                if (params.get('cancelled') === 'true') {
+                    this.showCancelMessage = true;
+                    window.history.replaceState({}, document.title, window.location.pathname);
+                }
+                if (params.get('addon_success') === 'true') {
+                    this.showAddonSuccessMessage = true;
+                    window.history.replaceState({}, document.title, window.location.pathname);
+                }
+
+                await this.loadData();
+            } catch (error) {
+                billingLog.error('Failed to initialize billing page:', error);
+            }
         },
 
         async loadData() {
diff --git a/static/vendor/js/content-page-edit.js b/static/vendor/js/content-page-edit.js
index 58e608db..e980e62d 100644
--- a/static/vendor/js/content-page-edit.js
+++ b/static/vendor/js/content-page-edit.js
@@ -37,9 +37,6 @@ function vendorContentPageEditor(pageId) {
 
         // Initialize
         async init() {
-            contentPageEditLog.info('=== VENDOR CONTENT PAGE EDITOR INITIALIZING ===');
-            contentPageEditLog.info('Page ID:', this.pageId);
-
             // Prevent multiple initializations
             if (window._vendorContentPageEditInitialized) {
                 contentPageEditLog.warn('Content page editor already initialized, skipping...');
@@ -47,17 +44,24 @@ function vendorContentPageEditor(pageId) {
             }
             window._vendorContentPageEditInitialized = true;
 
-            if (this.pageId) {
-                // Edit mode - load existing page
-                contentPageEditLog.group('Loading page for editing');
-                await this.loadPage();
-                contentPageEditLog.groupEnd();
-            } else {
-                // Create mode - use default values
-                contentPageEditLog.info('Create mode - using default form values');
-            }
+            try {
+                contentPageEditLog.info('=== VENDOR CONTENT PAGE EDITOR INITIALIZING ===');
+                contentPageEditLog.info('Page ID:', this.pageId);
 
-            contentPageEditLog.info('=== VENDOR CONTENT PAGE EDITOR INITIALIZATION COMPLETE ===');
+                if (this.pageId) {
+                    // Edit mode - load existing page
+                    contentPageEditLog.group('Loading page for editing');
+                    await this.loadPage();
+                    contentPageEditLog.groupEnd();
+                } else {
+                    // Create mode - use default values
+                    contentPageEditLog.info('Create mode - using default form values');
+                }
+
+                contentPageEditLog.info('=== VENDOR CONTENT PAGE EDITOR INITIALIZATION COMPLETE ===');
+            } catch (error) {
+                contentPageEditLog.error('Failed to initialize content page editor:', error);
+            }
         },
 
         // Load existing page
diff --git a/static/vendor/js/dashboard.js b/static/vendor/js/dashboard.js
index 5bc26795..4eb50b58 100644
--- a/static/vendor/js/dashboard.js
+++ b/static/vendor/js/dashboard.js
@@ -38,13 +38,17 @@ function vendorDashboard() {
             }
             window._vendorDashboardInitialized = true;
 
-            // IMPORTANT: Call parent init first to set vendorCode from URL
-            const parentInit = data().init;
-            if (parentInit) {
-                await parentInit.call(this);
-            }
+            try {
+                // IMPORTANT: Call parent init first to set vendorCode from URL
+                const parentInit = data().init;
+                if (parentInit) {
+                    await parentInit.call(this);
+                }
 
-            await this.loadDashboardData();
+                await this.loadDashboardData();
+            } catch (error) {
+                vendorDashLog.error('Failed to initialize dashboard:', error);
+            }
         },
 
         async loadDashboardData() {
@@ -94,7 +98,11 @@ function vendorDashboard() {
         },
 
         async refresh() {
-            await this.loadDashboardData();
+            try {
+                await this.loadDashboardData();
+            } catch (error) {
+                vendorDashLog.error('Failed to refresh dashboard:', error);
+            }
         },
 
         formatCurrency(amount) {
diff --git a/static/vendor/js/invoices.js b/static/vendor/js/invoices.js
index c0d8c79d..39e7765c 100644
--- a/static/vendor/js/invoices.js
+++ b/static/vendor/js/invoices.js
@@ -329,6 +329,7 @@ function vendorInvoices() {
                     throw new Error('Not authenticated');
                 }
 
+                // noqa: js-008 - File download needs response headers for filename
                 const response = await fetch(`/api/v1/vendor/invoices/${invoice.id}/pdf`, {
                     method: 'GET',
                     headers: {
diff --git a/static/vendor/js/letzshop.js b/static/vendor/js/letzshop.js
index 93a2df8d..06d1a413 100644
--- a/static/vendor/js/letzshop.js
+++ b/static/vendor/js/letzshop.js
@@ -438,6 +438,7 @@ function vendorLetzshop() {
                     throw new Error('Not authenticated');
                 }
 
+                // noqa: js-008 - File download needs response headers for filename
                 const response = await fetch(`/api/v1/vendor/letzshop/export?${params}`, {
                     method: 'GET',
                     headers: {
diff --git a/static/vendor/js/login.js b/static/vendor/js/login.js
index cc56dde6..38e0c645 100644
--- a/static/vendor/js/login.js
+++ b/static/vendor/js/login.js
@@ -24,24 +24,33 @@ function vendorLogin() {
         dark: false,
 
         async init() {
-            vendorLoginLog.info('=== VENDOR LOGIN PAGE INITIALIZING ===');
+            // Guard against multiple initialization
+            if (window._vendorLoginInitialized) return;
+            window._vendorLoginInitialized = true;
 
-            // Load theme
-            const theme = localStorage.getItem('theme');
-            if (theme === 'dark') {
-                this.dark = true;
-            }
-            vendorLoginLog.debug('Dark mode:', this.dark);
+            try {
+                vendorLoginLog.info('=== VENDOR LOGIN PAGE INITIALIZING ===');
 
-            // Get vendor code from URL path
-            const pathSegments = window.location.pathname.split('/').filter(Boolean);
-            if (pathSegments[0] === 'vendor' && pathSegments[1]) {
-                this.vendorCode = pathSegments[1];
-                vendorLoginLog.debug('Vendor code from URL:', this.vendorCode);
-                await this.loadVendor();
+                // Load theme
+                const theme = localStorage.getItem('theme');
+                if (theme === 'dark') {
+                    this.dark = true;
+                }
+                vendorLoginLog.debug('Dark mode:', this.dark);
+
+                // Get vendor code from URL path
+                const pathSegments = window.location.pathname.split('/').filter(Boolean);
+                if (pathSegments[0] === 'vendor' && pathSegments[1]) {
+                    this.vendorCode = pathSegments[1];
+                    vendorLoginLog.debug('Vendor code from URL:', this.vendorCode);
+                    await this.loadVendor();
+                }
+                this.checked = true;
+                vendorLoginLog.info('=== VENDOR LOGIN PAGE INITIALIZATION COMPLETE ===');
+            } catch (error) {
+                vendorLoginLog.error('Failed to initialize login page:', error);
+                this.checked = true;
             }
-            this.checked = true;
-            vendorLoginLog.info('=== VENDOR LOGIN PAGE INITIALIZATION COMPLETE ===');
         },
 
         async loadVendor() {
diff --git a/static/vendor/js/messages.js b/static/vendor/js/messages.js
index cb45f587..c7e59323 100644
--- a/static/vendor/js/messages.js
+++ b/static/vendor/js/messages.js
@@ -61,20 +61,28 @@ function vendorMessages(initialConversationId = null) {
          * Initialize component
          */
         async init() {
-            messagesLog.debug('Initializing vendor messages page');
-            await Promise.all([
-                this.loadConversations(),
-                this.loadRecipients()
-            ]);
+            // Guard against multiple initialization
+            if (window._vendorMessagesInitialized) return;
+            window._vendorMessagesInitialized = true;
 
-            if (this.selectedConversationId) {
-                await this.loadConversation(this.selectedConversationId);
+            try {
+                messagesLog.debug('Initializing vendor messages page');
+                await Promise.all([
+                    this.loadConversations(),
+                    this.loadRecipients()
+                ]);
+
+                if (this.selectedConversationId) {
+                    await this.loadConversation(this.selectedConversationId);
+                }
+
+                // Start polling for new messages
+                this.startPolling();
+            } catch (error) {
+                messagesLog.error('Failed to initialize messages page:', error);
+            } finally {
+                this.loading = false;
             }
-
-            this.loading = false;
-
-            // Start polling for new messages
-            this.startPolling();
         },
 
         /**
@@ -128,7 +136,7 @@ function vendorMessages(initialConversationId = null) {
                 messagesLog.debug(`Loaded ${this.conversations.length} conversations`);
             } catch (error) {
                 messagesLog.error('Failed to load conversations:', error);
-                window.showToast?.('Failed to load conversations', 'error');
+                Utils.showToast('Failed to load conversations', 'error');
             } finally {
                 this.loadingConversations = false;
             }
@@ -177,7 +185,7 @@ function vendorMessages(initialConversationId = null) {
                 this.scrollToBottom();
             } catch (error) {
                 messagesLog.error('Failed to load conversation:', error);
-                window.showToast?.('Failed to load conversation', 'error');
+                Utils.showToast('Failed to load conversation', 'error');
             } finally {
                 this.loadingMessages = false;
             }
@@ -231,20 +239,7 @@ function vendorMessages(initialConversationId = null) {
                 const formData = new FormData();
                 formData.append('content', this.replyContent);
 
-                const response = await fetch(`/api/v1/vendor/messages/${this.selectedConversationId}/messages`, {
-                    method: 'POST',
-                    body: formData,
-                    headers: {
-                        'Authorization': `Bearer ${window.getAuthToken?.() || ''}`
-                    }
-                });
-
-                if (!response.ok) {
-                    const error = await response.json();
-                    throw new Error(error.detail || 'Failed to send message');
-                }
-
-                const message = await response.json();
+                const message = await apiClient.postFormData(`/vendor/messages/${this.selectedConversationId}/messages`, formData);
 
                 // Add to messages
                 if (this.selectedConversation) {
@@ -260,7 +255,7 @@ function vendorMessages(initialConversationId = null) {
                 this.scrollToBottom();
             } catch (error) {
                 messagesLog.error('Failed to send message:', error);
-                window.showToast?.(error.message || 'Failed to send message', 'error');
+                Utils.showToast(error.message || 'Failed to send message', 'error');
             } finally {
                 this.sendingMessage = false;
             }
@@ -286,10 +281,10 @@ function vendorMessages(initialConversationId = null) {
                 const conv = this.conversations.find(c => c.id === this.selectedConversationId);
                 if (conv) conv.is_closed = true;
 
-                window.showToast?.('Conversation closed', 'success');
+                Utils.showToast('Conversation closed', 'success');
             } catch (error) {
                 messagesLog.error('Failed to close conversation:', error);
-                window.showToast?.('Failed to close conversation', 'error');
+                Utils.showToast('Failed to close conversation', 'error');
             }
         },
 
@@ -307,10 +302,10 @@ function vendorMessages(initialConversationId = null) {
                 const conv = this.conversations.find(c => c.id === this.selectedConversationId);
                 if (conv) conv.is_closed = false;
 
-                window.showToast?.('Conversation reopened', 'success');
+                Utils.showToast('Conversation reopened', 'success');
             } catch (error) {
                 messagesLog.error('Failed to reopen conversation:', error);
-                window.showToast?.('Failed to reopen conversation', 'error');
+                Utils.showToast('Failed to reopen conversation', 'error');
             }
         },
 
@@ -354,10 +349,10 @@ function vendorMessages(initialConversationId = null) {
                 await this.loadConversations();
                 await this.selectConversation(response.id);
 
-                window.showToast?.('Conversation created', 'success');
+                Utils.showToast('Conversation created', 'success');
             } catch (error) {
                 messagesLog.error('Failed to create conversation:', error);
-                window.showToast?.(error.message || 'Failed to create conversation', 'error');
+                Utils.showToast(error.message || 'Failed to create conversation', 'error');
             } finally {
                 this.creatingConversation = false;
             }
diff --git a/static/vendor/js/onboarding.js b/static/vendor/js/onboarding.js
index 2e16608a..8a84397e 100644
--- a/static/vendor/js/onboarding.js
+++ b/static/vendor/js/onboarding.js
@@ -345,7 +345,15 @@ function vendorOnboarding(initialLang = 'en') {
 
         // Initialize
         async init() {
-            await this.loadStatus();
+            // Guard against multiple initialization
+            if (window._vendorOnboardingInitialized) return;
+            window._vendorOnboardingInitialized = true;
+
+            try {
+                await this.loadStatus();
+            } catch (error) {
+                onboardingLog.error('Failed to initialize onboarding:', error);
+            }
         },
 
         // Load current onboarding status