diff --git a/README.md b/README.md
index 2245bb1..9749a14 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ pip install flask werkzeug --break-system-packages
 ### 2. Initialize Database
 
 ```bash
-cd /home/claude/scanlook
+cd /path/to/scanlook
 python database/init_db.py
 ```
 
@@ -39,7 +39,7 @@ Access at: **http://localhost:5000**
 
 ## 📱 Accessing from Scanner Devices
 
-For Zebra Android scanners or tablets on the same network:
+For Zebra MC9300 scanners or tablets on the same network:
 
 1. Find your server's IP address:
    ```bash
@@ -55,11 +55,32 @@ For Zebra Android scanners or tablets on the same network:
 
 ---
 
+## 🏗️ Modular Architecture
+
+ScanLook uses a modular system designed to grow into a full WMS. Modules can be enabled/disabled per user.
+
+### Current Modules:
+- **Counts** - Cycle Counts and Physical Inventory
+
+### Planned Modules:
+- Shipping
+- Receiving
+- Transfers
+- Production
+
+### Module Access
+- Admins assign modules to users via User Management
+- Users only see modules they have access to on the home screen
+- Route guards prevent URL bypassing
+
+---
+
 ## 👥 User Roles
 
 ### Owner (Level 1)
 - Super admin privileges
-- Manage all admins
+- Manage all users (admins and staff)
+- Access to all modules
 - View all sessions across branches
 
 ### Admin (Level 2)
@@ -68,9 +89,10 @@ For Zebra Android scanners or tablets on the same network:
 - Upload CURRENT baseline (refresh anytime)
 - View real-time dashboard
 - Export variance reports
-- Manage staff users
+- Manage staff users and module assignments
 
 ### Staff/Counter (Level 3)
+- Access assigned modules only
 - Select active count session
 - Scan locations and lots
 - Enter weights
@@ -79,36 +101,36 @@ For Zebra Android scanners or tablets on the same network:
 
 ---
 
-## 🔄 Core Workflow
+## 🔄 Core Workflow (Counts Module)
 
 ### Phase 1: Session Setup (Admin)
 
 1. **Log in as admin**
-2. **Create new count session**:
+2. **Navigate to Admin Console**
+3. **Create new count session**:
    - Session name: "January 17, 2026 - Daily Cycle Count"
    - Type: Cycle Count OR Full Physical Inventory
-3. **Upload MASTER baseline** CSV from NetSuite:
+4. **Upload MASTER baseline** CSV from NetSuite:
    - Format: `Item, Description, Lot Number, Location, Bin Number, On Hand`
-   - Creates baseline version 1
-4. Session status: **Active**
-5. Counters can now begin
+5. Session status: **Active**
+6. Counters can now begin
 
 ### Phase 2: Counting (Staff)
 
 1. **Log in as staff**
-2. **Select active session**
-3. **Scan location barcode** (e.g., R903B)
-   - System marks location "in progress"
-   - Shows: "Counting R903B"
-4. **Scan lot barcode**
-5. System checks lot against MASTER baseline:
+2. **Select Counts module** from home screen
+3. **Select active session**
+4. **Start a new bin** - scan or enter bin number
+5. **Scan lot barcode**
+6. System checks lot against MASTER baseline:
    - ✅ **MATCH**: Expected here, location correct
    - ⚠️ **WRONG LOCATION**: Lot exists but system says different location
    - ❌ **GHOST LOT**: Not in system at all
-6. **Enter weight**
-7. Save → returns to scan input (autofocus)
-8. Repeat for all lots in location
-9. Click **"Finish Location"**
+   - 🔵 **DUPLICATE**: Lot already scanned (same or different location)
+7. **Enter weight**
+8. Save → returns to scan input (autofocus)
+9. Repeat for all lots in bin
+10. Click **"Finish Location"** to finalize
 
 ### Phase 3: Admin Monitoring
 
@@ -155,8 +177,9 @@ Item,Description,Lot Number,Location,Bin Number,On Hand
 - What counters validate against
 - Represents "what should have been there when we started"
 
-**CURRENT Baseline**:
+**CURRENT Baseline** (Global):
 - Admin can refresh unlimited times
+- Shared across all sessions
 - Only affects admin dashboard/reporting  
 - Counters never see it
 - Shows "where is it in the system NOW"
@@ -170,16 +193,29 @@ Item,Description,Lot Number,Location,Bin Number,On Hand
 - **Ghost Lot**: Scanned but not in baseline at all
 - **Missing/Phantom**: In baseline but not found during count
 
-### Blind Counting
+### Duplicate Detection
 
-- Counters don't see expected quantities
-- Prevents bias
-- Ensures honest count
+- **Status 00**: First scan of lot (no duplicate)
+- **Status 01**: Duplicate in same location by same user
+- **Status 03**: Found in different location
+- **Status 04**: Both same location duplicate AND different location
+
+### Count Types
+
+**Cycle Count:**
+- Shows expected lots for the bin
+- Staff can see what should be there
+- Good for regular inventory checks
+
+**Full Physical Inventory:**
+- Blind count (no expected list shown)
+- Staff only sees what they've scanned
+- Missing lots determined after finalization
 
 ### Real-Time Dashboard
 
-- Active counters with current location
-- Progress by location
+- Active sessions with progress stats
+- Location completion tracking
 - Variance counts updating live
 - Dual view (MASTER vs CURRENT) after refresh
 
@@ -188,32 +224,38 @@ Item,Description,Lot Number,Location,Bin Number,On Hand
 - Every scan timestamped with user
 - Soft deletes tracked
 - Edits tracked with modified timestamp
-- Baseline version tracking
+- Session archival (archived sessions are read-only)
 
 ---
 
 ## 🗂️ Database Schema
 
-### Tables:
+### Core Tables:
 - **Users**: Authentication and role management
+- **Modules**: Available system modules
+- **UserModules**: Per-user module access
 - **CountSessions**: Count session metadata
-- **BaselineInventory_Master**: Morning baseline (never changes)
-- **BaselineInventory_Current**: Refreshable baseline (soft delete)
-- **LocationCounts**: Location-by-location progress
-- **ScanEntries**: Every lot scan with dual status tracking
-- **MissingLots**: Expected lots not found
+- **BaselineInventory_Master**: Session-specific baseline (immutable)
+- **BaselineInventory_Current**: Global refreshable baseline
+- **LocationCounts**: Bin-by-bin progress tracking
+- **ScanEntries**: Every lot scan with status tracking
+- **MissingLots**: Expected lots not found after finalization
 
-### Indexes:
-Optimized for fast lookups on lot numbers, locations, and statuses.
+### Key Relationships:
+- Users → UserModules → Modules (many-to-many)
+- CountSessions → BaselineInventory_Master (one-to-many)
+- CountSessions → LocationCounts → ScanEntries (hierarchical)
 
 ---
 
 ## 🔧 Technology Stack
 
 - **Backend**: Python 3.13 + Flask
-- **Database**: SQLite
+- **Database**: SQLite (auto-initializes on first run)
 - **Frontend**: HTML5 + CSS3 + Vanilla JavaScript
 - **Templates**: Jinja2
+- **Icons**: Font Awesome 6.5
+- **Deployment**: Docker (Linux)
 
 ---
 
@@ -221,23 +263,37 @@ Optimized for fast lookups on lot numbers, locations, and statuses.
 
 ```
 scanlook/
-├── app.py                 # Main Flask application
+├── app.py                 # Main Flask application & routes
+├── db.py                  # Database helper functions
+├── utils.py               # Decorators (login_required, role_required)
+├── blueprints/
+│   ├── counting.py        # Counts module routes
+│   ├── sessions.py        # Session management routes
+│   ├── users.py           # User management routes
+│   ├── data_imports.py    # CSV upload routes
+│   └── admin_locations.py # Admin location management
 ├── database/
-│   ├── init_db.py         # Database initialization
-│   └── scanlook.db        # SQLite database (created)
+│   ├── init_db.py         # Database initialization & schema
+│   └── scanlook.db        # SQLite database (created at runtime)
 ├── static/
 │   ├── css/
-│   │   └── style.css      # Main stylesheet
-│   └── js/
-│       └── main.js        # Client-side JavaScript
+│   │   ├── style.css      # Base/desktop styles
+│   │   ├── mobile.css     # Mobile overrides (360-767px)
+│   │   └── scanner.css    # MC9300 scanner overrides (<360px)
+│   ├── js/
+│   │   └── main.js        # Client-side JavaScript
+│   ├── manifest.json      # PWA manifest
+│   └── sw.js              # Service worker
 └── templates/
-    ├── base.html          # Base template
+    ├── base.html          # Base template with navbar
     ├── login.html         # Login page
+    ├── home.html          # Module selection (landing page)
     ├── admin_dashboard.html
     ├── staff_dashboard.html
+    ├── manage_users.html
     ├── create_session.html
     ├── session_detail.html
-    ├── count_session.html
+    ├── my_counts.html
     └── count_location.html
 ```
 
@@ -245,7 +301,7 @@ scanlook/
 
 ## 🎨 Design Philosophy
 
-**Mobile-First, Warehouse-Optimized:**
+**Desktop-First, Multi-Device Optimized:**
 - High contrast dark theme for warehouse lighting
 - Large touch targets (44px minimum)
 - Autofocus on scan inputs
@@ -253,52 +309,47 @@ scanlook/
 - Visual feedback with color-coded statuses
 - Minimal typing required
 
+**CSS Architecture:**
+- `style.css` - Base/desktop styles (768px+)
+- `mobile.css` - Phone overrides (360-767px)
+- `scanner.css` - MC9300 scanner overrides (<360px)
+
 **Color Coding:**
-- ✅ Green: Perfect match
-- ⚠️ Yellow: Wrong location
-- ❌ Red: Missing or ghost lot
-- 🔵 Blue: Weight variance
+- ✅ Green (`--color-success`): Perfect match
+- ⚠️ Yellow (`--color-warning`): Wrong location / Expected
+- ❌ Red (`--color-danger`): Missing or ghost lot
+- 🔵 Blue (`--color-duplicate`): Duplicate scan
+- 🟠 Orange (`--color-orange`): Weight variance
 
 ---
 
-## 🚧 Current Status: Phase 1 Complete (MVP)
+## 🐳 Docker Deployment
 
-### ✅ Implemented:
-- User authentication (3 roles)
-- Session creation
-- MASTER baseline upload
-- Location scanning
-- Lot scanning with MASTER status
-- Weight entry
-- Basic dashboard
-- Real-time progress tracking
-- Mobile-optimized UI
+```bash
+# Build
+docker build -t scanlook .
 
-### 🔜 Next Phases:
-- **Phase 2**: CURRENT baseline refresh & dual status recalculation
-- **Phase 3**: Missing lot detection, enhanced dashboard
-- **Phase 4**: Excel export with multiple tabs
-- **Phase 5**: Data retention automation, user management
-- **Phase 6**: Docker deployment
+# Run (preserves database between updates)
+docker run -d \
+  -p 5000:5000 \
+  -v /path/to/data:/app/database \
+  -e SCANLOOK_SECRET_KEY=your-secret-key \
+  scanlook
+```
+
+**Important:** Only `/app/database` is volume-mounted to preserve data between container updates.
 
 ---
 
-## 📝 Development Notes
+## 🔐 Security Considerations
 
-### Default Accounts (Testing)
-All passwords should be changed in production!
-
-### Security Considerations
-- Passwords are hashed with Werkzeug
+- Passwords hashed with Werkzeug
 - Session management via Flask sessions
 - SQL injection prevention (parameterized queries)
+- Role-based access control
+- Module-based access control with route guards
 - Soft deletes preserve audit trail
 
-### Data Retention
-- Plan: Keep data for 30 days
-- Nightly cleanup job (to be implemented)
-- Archive old sessions
-
 ---
 
 ## 🎯 Success Metrics
@@ -319,6 +370,7 @@ All passwords should be changed in production!
 
 ## 💡 Future Enhancements
 
+- Additional WMS modules (Shipping, Receiving, Transfers, Production)
 - Multi-branch support
 - Direct NetSuite API integration
 - Photo capture for variance proof
@@ -328,7 +380,16 @@ All passwords should be changed in production!
 
 ---
 
-## 📧 Support
+## 📝 Version History
+
+- **v0.12.0** - Modular architecture with user-based module access
+- **v0.11.x** - CSS refactoring, multi-device support, duplicate detection
+- **v0.10.x** - Global CURRENT baseline, session archival
+- **v0.9.x** - Core counting workflow, dual baseline system
+
+---
+
+## 🔧 Support
 
 This is a custom internal tool. Contact your system administrator for support.
 
diff --git a/app.py b/app.py
index c1a4839..77b8c97 100644
--- a/app.py
+++ b/app.py
@@ -36,7 +36,7 @@ app.config['PERMANENT_SESSION_LIFETIME'] = timedelta(hours=1)
 
 
 # 1. Define the version
-APP_VERSION = '0.12.0'
+APP_VERSION = '0.12.1'
 
 # 2. Inject it into all templates automatically
 @app.context_processor