diff --git a/pyproject.toml b/pyproject.toml
index e70db6d..b3dd238 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,12 +38,16 @@ dev = [
     "ruff>=0.1.0",
     "mypy>=1.0.0",
 ]
+gui = [
+    "customtkinter>=5.2.0",
+]
 pdf = [
     "pandoc",  # For PDF generation fallback
 ]
 
 [project.scripts]
 cad-doc = "cad_documenter.cli:main"
+cad-doc-gui = "cad_documenter.gui:main"
 
 [project.urls]
 Homepage = "http://100.80.199.40:3000/Antoine/CAD-Documenter"
diff --git a/src/cad_documenter/gui.py b/src/cad_documenter/gui.py
new file mode 100644
index 0000000..4a6daf3
--- /dev/null
+++ b/src/cad_documenter/gui.py
@@ -0,0 +1,312 @@
+"""CAD-Documenter GUI - Windows interface for project management."""
+
+import tkinter as tk
+from tkinter import ttk, filedialog, messagebox
+from pathlib import Path
+import threading
+import json
+
+try:
+    import customtkinter as ctk
+    ctk.set_appearance_mode("dark")
+    ctk.set_default_color_theme("blue")
+    USE_CTK = True
+except ImportError:
+    USE_CTK = False
+    ctk = tk  # Fallback to regular tkinter
+
+from .project import Project
+from .incremental import IncrementalProcessor
+from .config import load_config
+
+
+class CADDocumenterGUI:
+    """Main GUI application."""
+    
+    def __init__(self):
+        self.root = ctk.CTk() if USE_CTK else tk.Tk()
+        self.root.title("CAD Documenter")
+        self.root.geometry("700x600")
+        
+        self.current_project: Project | None = None
+        self.config = load_config()
+        
+        self._create_widgets()
+        self._update_project_list()
+    
+    def _create_widgets(self):
+        """Create the main UI widgets."""
+        # Main container
+        main_frame = ctk.CTkFrame(self.root) if USE_CTK else ttk.Frame(self.root)
+        main_frame.pack(fill="both", expand=True, padx=10, pady=10)
+        
+        # Project selection
+        project_frame = ctk.CTkFrame(main_frame) if USE_CTK else ttk.LabelFrame(main_frame, text="Project")
+        project_frame.pack(fill="x", pady=(0, 10))
+        
+        if USE_CTK:
+            ctk.CTkLabel(project_frame, text="Project:").pack(side="left", padx=5)
+        else:
+            ttk.Label(project_frame, text="Project:").pack(side="left", padx=5)
+        
+        self.project_var = tk.StringVar()
+        self.project_combo = ctk.CTkComboBox(
+            project_frame, 
+            variable=self.project_var,
+            values=[],
+            command=self._on_project_selected
+        ) if USE_CTK else ttk.Combobox(project_frame, textvariable=self.project_var)
+        self.project_combo.pack(side="left", fill="x", expand=True, padx=5)
+        
+        if not USE_CTK:
+            self.project_combo.bind("<<ComboboxSelected>>", lambda e: self._on_project_selected(None))
+        
+        btn_new = ctk.CTkButton(project_frame, text="+ New", width=70, command=self._new_project) if USE_CTK else ttk.Button(project_frame, text="+ New", command=self._new_project)
+        btn_new.pack(side="left", padx=5)
+        
+        btn_open = ctk.CTkButton(project_frame, text="Open", width=70, command=self._open_project) if USE_CTK else ttk.Button(project_frame, text="Open", command=self._open_project)
+        btn_open.pack(side="left", padx=5)
+        
+        # Videos list
+        videos_frame = ctk.CTkFrame(main_frame) if USE_CTK else ttk.LabelFrame(main_frame, text="Videos")
+        videos_frame.pack(fill="both", expand=True, pady=(0, 10))
+        
+        if USE_CTK:
+            ctk.CTkLabel(videos_frame, text="Videos:").pack(anchor="w", padx=5, pady=5)
+        
+        # Listbox for videos
+        list_frame = ctk.CTkFrame(videos_frame) if USE_CTK else ttk.Frame(videos_frame)
+        list_frame.pack(fill="both", expand=True, padx=5, pady=5)
+        
+        self.video_listbox = tk.Listbox(list_frame, height=10, selectmode="extended")
+        self.video_listbox.pack(side="left", fill="both", expand=True)
+        
+        scrollbar = ttk.Scrollbar(list_frame, orient="vertical", command=self.video_listbox.yview)
+        scrollbar.pack(side="right", fill="y")
+        self.video_listbox.config(yscrollcommand=scrollbar.set)
+        
+        # Video buttons
+        video_btn_frame = ctk.CTkFrame(videos_frame) if USE_CTK else ttk.Frame(videos_frame)
+        video_btn_frame.pack(fill="x", padx=5, pady=5)
+        
+        btn_add = ctk.CTkButton(video_btn_frame, text="Add Videos", command=self._add_videos) if USE_CTK else ttk.Button(video_btn_frame, text="Add Videos", command=self._add_videos)
+        btn_add.pack(side="left", padx=5)
+        
+        btn_remove = ctk.CTkButton(video_btn_frame, text="Remove", command=self._remove_video) if USE_CTK else ttk.Button(video_btn_frame, text="Remove", command=self._remove_video)
+        btn_remove.pack(side="left", padx=5)
+        
+        # Drop zone hint
+        if USE_CTK:
+            ctk.CTkLabel(video_btn_frame, text="(Drag & drop videos here)", text_color="gray").pack(side="right", padx=5)
+        
+        # Options
+        options_frame = ctk.CTkFrame(main_frame) if USE_CTK else ttk.LabelFrame(main_frame, text="Options")
+        options_frame.pack(fill="x", pady=(0, 10))
+        
+        if USE_CTK:
+            ctk.CTkLabel(options_frame, text="Options:").pack(anchor="w", padx=5, pady=5)
+        
+        self.export_only_var = tk.BooleanVar(value=True)
+        cb_export = ctk.CTkCheckBox(options_frame, text="Export for Clawdbot (no API)", variable=self.export_only_var) if USE_CTK else ttk.Checkbutton(options_frame, text="Export for Clawdbot (no API)", variable=self.export_only_var)
+        cb_export.pack(anchor="w", padx=20, pady=2)
+        
+        self.scene_detect_var = tk.BooleanVar(value=True)
+        cb_scene = ctk.CTkCheckBox(options_frame, text="Use scene detection", variable=self.scene_detect_var) if USE_CTK else ttk.Checkbutton(options_frame, text="Use scene detection", variable=self.scene_detect_var)
+        cb_scene.pack(anchor="w", padx=20, pady=2)
+        
+        self.transcribe_var = tk.BooleanVar(value=True)
+        cb_trans = ctk.CTkCheckBox(options_frame, text="Whisper transcription", variable=self.transcribe_var) if USE_CTK else ttk.Checkbutton(options_frame, text="Whisper transcription", variable=self.transcribe_var)
+        cb_trans.pack(anchor="w", padx=20, pady=2)
+        
+        # Process button
+        self.btn_process = ctk.CTkButton(
+            main_frame, 
+            text="Process Videos", 
+            height=40,
+            command=self._process_videos
+        ) if USE_CTK else ttk.Button(main_frame, text="Process Videos", command=self._process_videos)
+        self.btn_process.pack(fill="x", pady=(0, 10))
+        
+        # Status
+        status_frame = ctk.CTkFrame(main_frame) if USE_CTK else ttk.Frame(main_frame)
+        status_frame.pack(fill="x")
+        
+        self.status_var = tk.StringVar(value="Ready")
+        status_label = ctk.CTkLabel(status_frame, textvariable=self.status_var) if USE_CTK else ttk.Label(status_frame, textvariable=self.status_var)
+        status_label.pack(side="left", padx=5)
+        
+        self.progress = ctk.CTkProgressBar(status_frame) if USE_CTK else ttk.Progressbar(status_frame, mode="indeterminate")
+        self.progress.pack(side="right", fill="x", expand=True, padx=5)
+        if USE_CTK:
+            self.progress.set(0)
+    
+    def _update_project_list(self):
+        """Update the project dropdown with recent projects."""
+        # For now, just clear - could load from config/history
+        pass
+    
+    def _on_project_selected(self, value):
+        """Handle project selection."""
+        self._refresh_video_list()
+    
+    def _new_project(self):
+        """Create a new project."""
+        folder = filedialog.askdirectory(title="Select folder for new project")
+        if not folder:
+            return
+        
+        name = Path(folder).name
+        # Simple dialog for project name
+        dialog = ctk.CTkInputDialog(
+            text="Enter project name:", 
+            title="New Project"
+        ) if USE_CTK else None
+        
+        if USE_CTK:
+            name = dialog.get_input() or name
+        
+        try:
+            self.current_project = Project.create(Path(folder), name, "")
+            self.project_var.set(f"{name} ({folder})")
+            self.status_var.set(f"Created project: {name}")
+            self._refresh_video_list()
+        except Exception as e:
+            messagebox.showerror("Error", str(e))
+    
+    def _open_project(self):
+        """Open an existing project."""
+        folder = filedialog.askdirectory(title="Select project folder")
+        if not folder:
+            return
+        
+        try:
+            self.current_project = Project.load(Path(folder))
+            self.project_var.set(f"{self.current_project.manifest.name} ({folder})")
+            self.status_var.set(f"Loaded project: {self.current_project.manifest.name}")
+            self._refresh_video_list()
+        except Exception as e:
+            messagebox.showerror("Error", f"Failed to load project: {e}")
+    
+    def _refresh_video_list(self):
+        """Refresh the video listbox."""
+        self.video_listbox.delete(0, tk.END)
+        
+        if not self.current_project:
+            return
+        
+        for video in self.current_project.manifest.videos:
+            status_icon = {
+                "pending": "⏳",
+                "processed": "✓",
+                "exported": "📤",
+                "error": "✗"
+            }.get(video.status, "?")
+            
+            self.video_listbox.insert(tk.END, f"{status_icon} {video.filename}")
+    
+    def _add_videos(self):
+        """Add videos to the project."""
+        if not self.current_project:
+            messagebox.showwarning("Warning", "Please create or open a project first")
+            return
+        
+        files = filedialog.askopenfilenames(
+            title="Select videos",
+            filetypes=[
+                ("Video files", "*.mp4 *.mkv *.avi *.mov *.webm"),
+                ("All files", "*.*")
+            ]
+        )
+        
+        for f in files:
+            try:
+                self.current_project.add_video(Path(f), copy=True)
+            except Exception as e:
+                messagebox.showerror("Error", f"Failed to add {f}: {e}")
+        
+        self._refresh_video_list()
+        self.status_var.set(f"Added {len(files)} video(s)")
+    
+    def _remove_video(self):
+        """Remove selected video from project."""
+        # TODO: Implement video removal
+        messagebox.showinfo("Info", "Video removal not yet implemented")
+    
+    def _process_videos(self):
+        """Process videos in background thread."""
+        if not self.current_project:
+            messagebox.showwarning("Warning", "Please create or open a project first")
+            return
+        
+        pending = self.current_project.get_pending_videos()
+        if not pending:
+            messagebox.showinfo("Info", "No pending videos to process")
+            return
+        
+        # Disable button during processing
+        self.btn_process.configure(state="disabled")
+        self.status_var.set("Processing...")
+        
+        if USE_CTK:
+            self.progress.set(0)
+            self.progress.start()
+        else:
+            self.progress.start()
+        
+        def process_thread():
+            try:
+                processor = IncrementalProcessor(self.current_project, self.config)
+                results = processor.process_pending(
+                    export_only=self.export_only_var.get()
+                )
+                
+                self.root.after(0, lambda: self._on_process_complete(results))
+            except Exception as e:
+                self.root.after(0, lambda: self._on_process_error(str(e)))
+        
+        thread = threading.Thread(target=process_thread, daemon=True)
+        thread.start()
+    
+    def _on_process_complete(self, results):
+        """Handle processing completion."""
+        if USE_CTK:
+            self.progress.stop()
+            self.progress.set(1)
+        else:
+            self.progress.stop()
+        
+        self.btn_process.configure(state="normal")
+        self._refresh_video_list()
+        
+        msg = f"Processed {results.get('processed', 0)} video(s)"
+        if self.export_only_var.get():
+            msg += f"\n\nExports ready! Tell Clawdbot:\n\"Process CAD report for {self.current_project.manifest.name}\""
+        
+        self.status_var.set("Complete!")
+        messagebox.showinfo("Success", msg)
+    
+    def _on_process_error(self, error):
+        """Handle processing error."""
+        if USE_CTK:
+            self.progress.stop()
+            self.progress.set(0)
+        else:
+            self.progress.stop()
+        
+        self.btn_process.configure(state="normal")
+        self.status_var.set("Error")
+        messagebox.showerror("Error", f"Processing failed: {error}")
+    
+    def run(self):
+        """Run the application."""
+        self.root.mainloop()
+
+
+def main():
+    """Entry point for GUI."""
+    app = CADDocumenterGUI()
+    app.run()
+
+
+if __name__ == "__main__":
+    main()