diff --git a/CLAUDE.md b/CLAUDE.md
index 727d4a79..75d42dd1 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -4,13 +4,16 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-This is a local Arduino emulator (Wokwi clone) that provides a full development environment for Arduino projects:
+**Velxio** — a fully local, open-source Arduino emulator (formerly OpenWokwi).
+- GitHub: https://github.com/davidmonterocrespo24/velxio
 - Frontend: React + Vite + TypeScript with Monaco Editor and visual simulation canvas
 - Backend: FastAPI + Python for Arduino code compilation via arduino-cli
 - Simulation: Real AVR8 emulation using avr8js with full GPIO/timer/USART support
 - Components: Visual electronic components from wokwi-elements (LEDs, resistors, buttons, etc.)
+- Auth: Email/password + Google OAuth, JWT in httpOnly cookies
+- Project persistence: SQLite via SQLAlchemy 2.0 async + aiosqlite
 
-The project uses **local clones of official Wokwi repositories** instead of npm packages for maximum compatibility and ease of updates.
+The project uses **local clones of official Wokwi repositories** in `wokwi-libs/` instead of npm packages.
 
 ## Development Commands
 
@@ -55,6 +58,11 @@ cd frontend
 npm run build
 ```
 
+**Docker build (skips tsc type-check, uses esbuild only):**
+```bash
+npm run build:docker
+```
+
 **Lint:**
 ```bash
 cd frontend
@@ -69,7 +77,7 @@ npm run lint
 The project uses local clones of Wokwi repositories in `wokwi-libs/`:
 - `wokwi-elements/` - Web Components for electronic parts
 - `avr8js/` - AVR8 CPU emulator
-- `rp2040js/` - RP2040 emulator (future use)
+- `rp2040js/` - RP2040 emulator
 
 **Update libraries:**
 ```bash
@@ -101,7 +109,7 @@ arduino-cli core install arduino:avr
 ### High-Level Data Flow
 
 1. **Code Editing**: User writes Arduino code → Monaco Editor → Zustand store (`useEditorStore`)
-2. **Compilation**: Code → Frontend API call → Backend FastAPI → arduino-cli subprocess → Returns .hex file
+2. **Compilation**: Files → Frontend API call → Backend FastAPI → arduino-cli subprocess → Returns .hex file
 3. **Simulation**: .hex file → AVRSimulator.loadHex() → Parsed into Uint16Array → CPU execution loop
 4. **Pin Updates**: CPU writes to PORTB/C/D → Port listeners → PinManager → Component state updates
 5. **Visual Updates**: Component state changes → React re-renders → wokwi-elements update visually
@@ -120,31 +128,62 @@ resolve: {
 }
 ```
 
-This allows importing as if they were npm packages while using local clones.
+**2. Multi-File Workspace (useEditorStore)**
 
-**2. AVR Simulation Loop**
+The editor supports multiple files. `useEditorStore` holds:
+```typescript
+interface WorkspaceFile { id: string; name: string; content: string; modified: boolean; }
+// State:
+files: WorkspaceFile[]
+activeFileId: string
+openFileIds: string[]
+// Key operations:
+createFile, deleteFile, renameFile, setFileContent, markFileSaved,
+openFile, closeFile, setActiveFile, loadFiles, setCode (legacy)
+```
+`setCode` is a legacy setter that writes to the active file's content — used by old call sites.
+`loadFiles` replaces all files when loading a saved project.
+
+**3. Multi-File Compilation**
+
+The backend accepts an array of files, not a single code string:
+```typescript
+// Frontend (compilation.ts)
+interface SketchFile { name: string; content: string; }
+compileCode(files: SketchFile[], board: string)
+// sends: { files, board_fqbn: board }
+
+// Backend (compile.py)
+class SketchFile(BaseModel): name: str; content: str
+class CompileRequest:
+    files: list[SketchFile] | None = None
+    code: str | None = None  # legacy fallback
+```
+The backend promotes the first `.ino` to `sketch.ino` and applies RP2040 Serial redirect only to `sketch.ino`.
+
+**4. AVR Simulation Loop**
 
 The simulation runs at ~60 FPS using `requestAnimationFrame`:
 - Each frame executes ~267,000 CPU cycles (16MHz / 60fps)
 - Port listeners fire when PORTB/C/D registers change
 - PinManager maps Arduino pins to components (e.g., pin 13 → LED_BUILTIN)
 
-**3. State Management with Zustand**
+**5. State Management with Zustand**
 
-Two main stores:
-- `useEditorStore`: Code content, theme
-- `useSimulatorStore`: Simulation state, components, wires, compiled hex
+Main stores:
+- `useEditorStore`: Multi-file workspace (files[], activeFileId, openFileIds)
+- `useSimulatorStore`: Simulation state, components, wires, compiled hex, serialMonitorOpen
+- `useAuthStore`: Auth state (persisted in localStorage)
+- `useProjectStore`: Current project tracking
 
-**4. Component-Pin Mapping**
+**6. Component-Pin Mapping**
 
 Components are connected to Arduino pins via the PinManager:
 - PORTB maps to digital pins 8-13 (pin 13 = built-in LED)
 - PORTC maps to analog pins A0-A5
 - PORTD maps to digital pins 0-7
 
-When a port value changes, PinManager calls registered callbacks for affected components.
-
-**5. Wire System (Phase 1 - Visual Only)**
+**7. Wire System**
 
 Wires are stored as objects with start/end endpoints:
 ```typescript
@@ -156,32 +195,57 @@ Wires are stored as objects with start/end endpoints:
   signalType: 'digital' | 'analog' | 'power-vcc' | 'power-gnd'
 }
 ```
-
 Wire positions auto-update when components move via `updateWirePositions()`.
 
 ## Key File Locations
 
 ### Backend
-- [backend/app/main.py](backend/app/main.py) - FastAPI app entry point, CORS config
-- [backend/app/api/routes/compile.py](backend/app/api/routes/compile.py) - Compilation endpoints
-- [backend/app/services/arduino_cli.py](backend/app/services/arduino_cli.py) - arduino-cli wrapper, handles compilation subprocess
+- [backend/app/main.py](backend/app/main.py) - FastAPI app entry point, CORS config, model imports
+- [backend/app/api/routes/compile.py](backend/app/api/routes/compile.py) - Compilation endpoints (multi-file)
+- [backend/app/api/routes/auth.py](backend/app/api/routes/auth.py) - /api/auth/* endpoints
+- [backend/app/api/routes/projects.py](backend/app/api/routes/projects.py) - /api/projects/* + /api/user/*
+- [backend/app/services/arduino_cli.py](backend/app/services/arduino_cli.py) - arduino-cli wrapper
+- [backend/app/core/config.py](backend/app/core/config.py) - Settings (SECRET_KEY, DATABASE_URL `velxio.db`, GOOGLE_*)
+- [backend/app/core/security.py](backend/app/core/security.py) - JWT, password hashing
+- [backend/app/core/dependencies.py](backend/app/core/dependencies.py) - get_current_user, require_auth
+- [backend/app/database/session.py](backend/app/database/session.py) - async SQLAlchemy engine
+- [backend/app/models/user.py](backend/app/models/user.py) - User model
+- [backend/app/models/project.py](backend/app/models/project.py) - Project model (UniqueConstraint user_id+slug)
 
 ### Frontend - Core
-- [frontend/src/App.tsx](frontend/src/App.tsx) - Main app component
-- [frontend/src/store/useEditorStore.ts](frontend/src/store/useEditorStore.ts) - Code editor state
+- [frontend/src/App.tsx](frontend/src/App.tsx) - Main app component, routing
+- [frontend/src/store/useEditorStore.ts](frontend/src/store/useEditorStore.ts) - Multi-file workspace state
 - [frontend/src/store/useSimulatorStore.ts](frontend/src/store/useSimulatorStore.ts) - Simulation state, components, wires
+- [frontend/src/store/useAuthStore.ts](frontend/src/store/useAuthStore.ts) - Auth state (localStorage)
+- [frontend/src/store/useProjectStore.ts](frontend/src/store/useProjectStore.ts) - Current project
+
+### Frontend - Editor UI
+- [frontend/src/components/editor/CodeEditor.tsx](frontend/src/components/editor/CodeEditor.tsx) - Monaco editor (key={activeFileId} for per-file undo history)
+- [frontend/src/components/editor/EditorToolbar.tsx](frontend/src/components/editor/EditorToolbar.tsx) - Compile/Run/Stop buttons (reads files[], not code)
+- [frontend/src/components/editor/FileExplorer.tsx](frontend/src/components/editor/FileExplorer.tsx) - Sidebar file list with SVG icons, rename, delete, save button
+- [frontend/src/components/editor/FileTabs.tsx](frontend/src/components/editor/FileTabs.tsx) - Open file tabs with unsaved-changes indicator and close dialog
+
+### Frontend - Layout
+- [frontend/src/components/layout/AppHeader.tsx](frontend/src/components/layout/AppHeader.tsx) - Top header (no Save button — moved to FileExplorer)
+- [frontend/src/components/layout/SaveProjectModal.tsx](frontend/src/components/layout/SaveProjectModal.tsx) - Save/update project (reads files[], uses sketch.ino content)
+- [frontend/src/components/layout/LoginPromptModal.tsx](frontend/src/components/layout/LoginPromptModal.tsx) - Prompt anon users
 
 ### Frontend - Simulation
-- [frontend/src/simulation/AVRSimulator.ts](frontend/src/simulation/AVRSimulator.ts) - AVR8 CPU emulator wrapper, execution loop
+- [frontend/src/simulation/AVRSimulator.ts](frontend/src/simulation/AVRSimulator.ts) - AVR8 CPU emulator wrapper
 - [frontend/src/simulation/PinManager.ts](frontend/src/simulation/PinManager.ts) - Maps Arduino pins to components
 - [frontend/src/utils/hexParser.ts](frontend/src/utils/hexParser.ts) - Intel HEX format parser
+- [frontend/src/components/simulator/SimulatorCanvas.tsx](frontend/src/components/simulator/SimulatorCanvas.tsx) - Canvas + Serial button next to board selector
 
-### Frontend - UI Components
-- [frontend/src/components/editor/CodeEditor.tsx](frontend/src/components/editor/CodeEditor.tsx) - Monaco editor wrapper
-- [frontend/src/components/editor/EditorToolbar.tsx](frontend/src/components/editor/EditorToolbar.tsx) - Compile/Run/Stop buttons
-- [frontend/src/components/simulator/SimulatorCanvas.tsx](frontend/src/components/simulator/SimulatorCanvas.tsx) - Main simulation canvas
-- [frontend/src/components/simulator/WireLayer.tsx](frontend/src/components/simulator/WireLayer.tsx) - Wire rendering layer
-- [frontend/src/components/components-wokwi/](frontend/src/components/components-wokwi/) - React wrappers for wokwi-elements
+### Frontend - Pages
+- [frontend/src/pages/EditorPage.tsx](frontend/src/pages/EditorPage.tsx) - Main editor layout (resizable file explorer + panels)
+- [frontend/src/pages/LoginPage.tsx](frontend/src/pages/LoginPage.tsx)
+- [frontend/src/pages/RegisterPage.tsx](frontend/src/pages/RegisterPage.tsx)
+- [frontend/src/pages/UserProfilePage.tsx](frontend/src/pages/UserProfilePage.tsx) - Profile with project grid
+- [frontend/src/pages/ProjectPage.tsx](frontend/src/pages/ProjectPage.tsx) - Loads project into editor
+
+### Docker & CI
+- [Dockerfile.standalone](Dockerfile.standalone) - Multi-stage Docker build
+- [.github/workflows/docker-publish.yml](.github/workflows/docker-publish.yml) - Publishes to GHCR + Docker Hub on push to master
 
 ## Important Implementation Notes
 
@@ -193,8 +257,6 @@ avrInstruction(this.cpu);  // Execute the AVR instruction
 this.cpu.tick();           // Update peripheral timers and cycles
 ```
 
-Missing `avrInstruction()` will cause the CPU to appear "stuck" even though cycles increment.
-
 ### 2. Port Listeners
 
 Port listeners in AVRSimulator.ts are attached to AVRIOPort instances, NOT directly to CPU registers:
@@ -220,14 +282,6 @@ To add a component to the simulation:
 2. Register a pin change callback in PinManager
 3. Update component state when pin changes
 
-Example:
-```typescript
-pinManager.registerCallback(13, (state) => {
-  // Update LED when pin 13 changes
-  useSimulatorStore.getState().updateComponentState('led-builtin', state);
-});
-```
-
 ### 5. CORS Configuration
 
 Backend allows specific Vite dev ports (5173-5175). Update `backend/app/main.py` if using different ports.
@@ -245,6 +299,38 @@ declare global {
 }
 ```
 
+### 7. Pre-existing TypeScript Errors
+
+There are known pre-existing TS errors that do NOT block the app from running:
+- `wokwi-elements` JSX custom element types (`wokwi-led`, `wokwi-arduino-uno`, etc.)
+- `@monaco-editor/react` type compatibility with React 19
+- Test mock type mismatches in `AVRSimulator.test.ts`
+
+**Do not fix these unless explicitly asked.** They are suppressed in Docker builds by using `build:docker` which runs `vite build` only (no `tsc -b`). Local `npm run build` runs `tsc -b` and will show these errors.
+
+### 8. Docker Build — wokwi-libs
+
+The git submodule pointers for `rp2040js` and `wokwi-elements` in this repo are stale (point to very old commits that predate `package.json`). The `Dockerfile.standalone` works around this by **cloning the libs fresh from GitHub** at build time instead of COPYing from the build context:
+
+```dockerfile
+RUN git clone --depth=1 https://github.com/wokwi/avr8js.git wokwi-libs/avr8js \
+ && git clone --depth=1 https://github.com/wokwi/rp2040js.git wokwi-libs/rp2040js \
+ && git clone --depth=1 https://github.com/wokwi/wokwi-elements.git wokwi-libs/wokwi-elements
+```
+
+The GitHub Actions workflow does NOT use `submodules: recursive` for this reason.
+
+### 9. Backend Gotchas
+
+- **bcrypt**: Pin `bcrypt==4.0.1` — bcrypt 5.x breaks passlib 1.7.4
+- **email-validator**: Must be installed separately (`pip install email-validator`)
+- **Model imports**: Both `app.models.user` and `app.models.project` must be imported before DB init (done in `main.py`)
+- **RP2040 board manager**: arduino-cli needs the earlephilhower URL before `rp2040:rp2040` install:
+  ```
+  arduino-cli config add board_manager.additional_urls \
+    https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+  ```
+
 ## Testing
 
 ### Backend Testing
@@ -255,7 +341,11 @@ python test_compilation.py
 ```
 
 ### Frontend Testing
-No test suite currently implemented. Manual testing via dev server.
+Vitest is configured. Run tests:
+```bash
+cd frontend
+npm test
+```
 
 ## Common Development Scenarios
 
@@ -290,8 +380,10 @@ Enable verbose logging:
 
 **Implemented:**
 - Full Arduino code editing with Monaco Editor
-- Compilation via arduino-cli to .hex files
+- **Multi-file workspace** — create, rename, delete, open/close tabs, unsaved-changes indicator
+- Compilation via arduino-cli to .hex files (multi-file sketch support)
 - Real AVR8 emulation with avr8js
+- RP2040 emulation with rp2040js
 - Pin state tracking and component updates
 - Dynamic component system with 48+ wokwi-elements components
 - Component picker modal with search and categories
@@ -301,22 +393,29 @@ Enable verbose logging:
 - Segment-based wire editing (drag segments perpendicular to orientation)
 - Real-time wire preview with grid snapping (20px)
 - Pin overlay system for wire connections
+- Serial Monitor with baud rate detection and send
+- ILI9341 TFT display simulation
+- Library Manager (install/search arduino libraries)
+- Example projects gallery
+- **Auth**: email/password + Google OAuth, JWT httpOnly cookies
+- **Project persistence**: create/read/update/delete with URL slugs (`/:username/:slug`)
+- **User profile page** at `/:username`
+- **Resizable file explorer** panel (drag handle, collapse toggle)
+- Docker standalone image published to GHCR + Docker Hub
 
 **In Progress:**
 - Functional wire connections (electrical signal routing)
 - Wire validation and error handling
 
 **Planned:**
-- Serial monitor
-- Project persistence (SQLite)
-- Multi-board support (Mega, Nano, ESP32)
 - Undo/redo functionality
+- More boards (ESP32, Arduino Mega, Arduino Nano)
+- Export/Import projects as files
 
 ## Additional Resources
 
 - Main README: [README.md](README.md)
-- Architecture Details: [ARCHITECTURE.md](ARCHITECTURE.md)
-- Wokwi Integration: [WOKWI_LIBS.md](WOKWI_LIBS.md)
+- Architecture Details: [doc/ARCHITECTURE.md](doc/ARCHITECTURE.md)
 - Wokwi Elements Repo: https://github.com/wokwi/wokwi-elements
 - AVR8js Repo: https://github.com/wokwi/avr8js
 - Arduino CLI Docs: https://arduino.github.io/arduino-cli/