logo and architecture fixes

ARCHITECTURE-KNOWLEDGE-BASE.md

@@ -1,9 +1,34 @@
 # Architecture Knowledge Base
-**Last Updated:** December 8, 2025  
+**Last Updated:** December 9, 2025  
 **Purpose:** Critical architectural patterns, common issues, and solutions reference
 
 ---
 
+## 🔥 CRITICAL FIXES - December 9, 2025
+
+### PERMANENT FIX: User Swapping / Random Logout Issue
+**ROOT CAUSE**: Django's database-backed sessions with in-memory user caching caused cross-request contamination at the process level.
+
+**SOLUTION IMPLEMENTED**:
+1. ✅ Redis-backed sessions (`SESSION_ENGINE = 'django.contrib.sessions.backends.cache'`)
+2. ✅ Custom authentication backend without caching (`NoCacheModelBackend`)
+3. ✅ Session integrity validation (stores and verifies account_id/user_id on every request)
+4. ✅ Middleware never mutates `request.user` (uses Django's set value directly)
+
+**See**: `CRITICAL-BUG-FIXES-DEC-2025.md` for complete details.
+
+### PERMANENT FIX: useNavigate / useLocation Errors During HMR
+**ROOT CAUSE**: Individual Suspense boundaries per route lost React Router context during Hot Module Replacement.
+
+**SOLUTION IMPLEMENTED**:
+1. ✅ Single top-level Suspense boundary around entire `<Routes>` component
+2. ✅ Removed 100+ individual Suspense wrappers from route elements
+3. ✅ Router context now persists through HMR automatically
+
+**See**: `CRITICAL-BUG-FIXES-DEC-2025.md` for complete details.
+
+---
+
 ## Table of Contents
 1. [Authentication & Session Management](#authentication--session-management)
 2. [Site/Sector Architecture](#sitesector-architecture)