diff --git a/pyPhotoAlbum/asset_manager.py b/pyPhotoAlbum/asset_manager.py
index b3e1868..8c19b62 100644
--- a/pyPhotoAlbum/asset_manager.py
+++ b/pyPhotoAlbum/asset_manager.py
@@ -2,12 +2,37 @@
 Asset management system for pyPhotoAlbum with automatic reference counting
 """
 
+import hashlib
 import os
 import shutil
-from typing import Dict, Optional
+from typing import Dict, List, Optional, Tuple
 from pathlib import Path
 
 
+def compute_file_md5(file_path: str) -> Optional[str]:
+    """
+    Compute MD5 hash of a file.
+
+    Args:
+        file_path: Path to the file
+
+    Returns:
+        MD5 hash as hex string, or None if file doesn't exist
+    """
+    if not os.path.exists(file_path):
+        return None
+
+    hash_md5 = hashlib.md5()
+    try:
+        with open(file_path, "rb") as f:
+            for chunk in iter(lambda: f.read(8192), b""):
+                hash_md5.update(chunk)
+        return hash_md5.hexdigest()
+    except Exception as e:
+        print(f"AssetManager: Error computing MD5 for {file_path}: {e}")
+        return None
+
+
 class AssetManager:
     """Manages project assets with automatic reference counting and cleanup"""
 
@@ -21,6 +46,7 @@ class AssetManager:
         self.project_folder = project_folder
         self.assets_folder = os.path.join(project_folder, "assets")
         self.reference_counts: Dict[str, int] = {}  # {relative_path: count}
+        self.asset_hashes: Dict[str, str] = {}  # {relative_path: md5_hash}
 
         # Create assets folder if it doesn't exist
         os.makedirs(self.assets_folder, exist_ok=True)
@@ -143,9 +169,262 @@ class AssetManager:
 
     def serialize(self) -> Dict:
         """Serialize asset manager state"""
-        return {"reference_counts": self.reference_counts}
+        return {
+            "reference_counts": self.reference_counts,
+            "asset_hashes": self.asset_hashes,
+        }
 
     def deserialize(self, data: Dict):
         """Deserialize asset manager state"""
         self.reference_counts = data.get("reference_counts", {})
+        self.asset_hashes = data.get("asset_hashes", {})
         print(f"AssetManager: Loaded {len(self.reference_counts)} asset references")
+
+    def compute_asset_hash(self, asset_path: str) -> Optional[str]:
+        """
+        Compute and cache the MD5 hash for an asset.
+
+        Args:
+            asset_path: Relative path to the asset
+
+        Returns:
+            MD5 hash as hex string, or None if computation fails
+        """
+        full_path = self.get_absolute_path(asset_path)
+        md5_hash = compute_file_md5(full_path)
+        if md5_hash:
+            self.asset_hashes[asset_path] = md5_hash
+        return md5_hash
+
+    def compute_all_hashes(self) -> Dict[str, str]:
+        """
+        Compute MD5 hashes for all assets in the assets folder.
+
+        Returns:
+            Dictionary mapping relative paths to MD5 hashes
+        """
+        self.asset_hashes.clear()
+
+        if not os.path.exists(self.assets_folder):
+            return self.asset_hashes
+
+        for root, dirs, files in os.walk(self.assets_folder):
+            for filename in files:
+                file_path = os.path.join(root, filename)
+                relative_path = os.path.relpath(file_path, self.project_folder)
+                md5_hash = compute_file_md5(file_path)
+                if md5_hash:
+                    self.asset_hashes[relative_path] = md5_hash
+
+        print(f"AssetManager: Computed hashes for {len(self.asset_hashes)} assets")
+        return self.asset_hashes
+
+    def find_duplicates(self) -> Dict[str, List[str]]:
+        """
+        Find duplicate assets based on MD5 hash.
+
+        Returns:
+            Dictionary mapping MD5 hash to list of asset paths with that hash.
+            Only includes hashes with more than one file.
+        """
+        # Compute hashes if not already done
+        if not self.asset_hashes:
+            self.compute_all_hashes()
+
+        # Group assets by hash
+        hash_to_paths: Dict[str, List[str]] = {}
+        for path, md5_hash in self.asset_hashes.items():
+            if md5_hash not in hash_to_paths:
+                hash_to_paths[md5_hash] = []
+            hash_to_paths[md5_hash].append(path)
+
+        # Filter to only duplicates (more than one file with same hash)
+        duplicates = {h: paths for h, paths in hash_to_paths.items() if len(paths) > 1}
+
+        if duplicates:
+            total_dups = sum(len(paths) - 1 for paths in duplicates.values())
+            print(f"AssetManager: Found {total_dups} duplicate files in {len(duplicates)} groups")
+
+        return duplicates
+
+    def deduplicate_assets(self, update_references_callback=None) -> Tuple[int, int]:
+        """
+        Remove duplicate assets, keeping one canonical copy and updating references.
+
+        Args:
+            update_references_callback: Optional callback function that takes
+                (old_path, new_path) to update external references (e.g., ImageData elements)
+
+        Returns:
+            Tuple of (files_removed, bytes_saved)
+        """
+        duplicates = self.find_duplicates()
+        if not duplicates:
+            print("AssetManager: No duplicates found")
+            return (0, 0)
+
+        files_removed = 0
+        bytes_saved = 0
+
+        for md5_hash, paths in duplicates.items():
+            # Sort paths to get consistent canonical path (first alphabetically)
+            paths.sort()
+            canonical_path = paths[0]
+
+            # Remove duplicates and update references
+            for dup_path in paths[1:]:
+                full_dup_path = self.get_absolute_path(dup_path)
+
+                # Get file size before deletion
+                try:
+                    file_size = os.path.getsize(full_dup_path)
+                except OSError:
+                    file_size = 0
+
+                # Update references if callback provided
+                if update_references_callback:
+                    update_references_callback(dup_path, canonical_path)
+
+                # Transfer reference count to canonical path
+                if dup_path in self.reference_counts:
+                    dup_refs = self.reference_counts[dup_path]
+                    if canonical_path in self.reference_counts:
+                        self.reference_counts[canonical_path] += dup_refs
+                    else:
+                        self.reference_counts[canonical_path] = dup_refs
+                    del self.reference_counts[dup_path]
+
+                # Delete the duplicate file
+                try:
+                    if os.path.exists(full_dup_path):
+                        os.remove(full_dup_path)
+                        files_removed += 1
+                        bytes_saved += file_size
+                        print(f"AssetManager: Removed duplicate {dup_path} (kept {canonical_path})")
+                except Exception as e:
+                    print(f"AssetManager: Error removing duplicate {dup_path}: {e}")
+
+                # Remove from hash tracking
+                if dup_path in self.asset_hashes:
+                    del self.asset_hashes[dup_path]
+
+        print(f"AssetManager: Deduplication complete - removed {files_removed} files, saved {bytes_saved} bytes")
+        return (files_removed, bytes_saved)
+
+    def get_duplicate_stats(self) -> Tuple[int, int, int]:
+        """
+        Get statistics about duplicate assets without modifying anything.
+
+        Returns:
+            Tuple of (duplicate_groups, total_duplicate_files, estimated_bytes_to_save)
+        """
+        duplicates = self.find_duplicates()
+        if not duplicates:
+            return (0, 0, 0)
+
+        duplicate_groups = len(duplicates)
+        total_duplicate_files = sum(len(paths) - 1 for paths in duplicates.values())
+
+        # Calculate bytes that would be saved
+        bytes_to_save = 0
+        for paths in duplicates.values():
+            # Skip the first (canonical) file, count size of the rest
+            for dup_path in paths[1:]:
+                full_path = self.get_absolute_path(dup_path)
+                try:
+                    bytes_to_save += os.path.getsize(full_path)
+                except OSError:
+                    pass
+
+        return (duplicate_groups, total_duplicate_files, bytes_to_save)
+
+    def find_unused_assets(self) -> List[str]:
+        """
+        Find assets that exist in the assets folder but have no references.
+
+        Returns:
+            List of relative paths to unused assets
+        """
+        unused = []
+
+        if not os.path.exists(self.assets_folder):
+            return unused
+
+        # Get all files in assets folder
+        for root, dirs, files in os.walk(self.assets_folder):
+            for filename in files:
+                file_path = os.path.join(root, filename)
+                relative_path = os.path.relpath(file_path, self.project_folder)
+
+                # Check if this asset has any references
+                ref_count = self.reference_counts.get(relative_path, 0)
+                if ref_count <= 0:
+                    unused.append(relative_path)
+
+        if unused:
+            print(f"AssetManager: Found {len(unused)} unused assets")
+
+        return unused
+
+    def get_unused_stats(self) -> Tuple[int, int]:
+        """
+        Get statistics about unused assets without modifying anything.
+
+        Returns:
+            Tuple of (unused_file_count, total_bytes)
+        """
+        unused = self.find_unused_assets()
+        if not unused:
+            return (0, 0)
+
+        total_bytes = 0
+        for asset_path in unused:
+            full_path = self.get_absolute_path(asset_path)
+            try:
+                total_bytes += os.path.getsize(full_path)
+            except OSError:
+                pass
+
+        return (len(unused), total_bytes)
+
+    def remove_unused_assets(self) -> Tuple[int, int]:
+        """
+        Remove all unused assets from the assets folder.
+
+        Returns:
+            Tuple of (files_removed, bytes_freed)
+        """
+        unused = self.find_unused_assets()
+        if not unused:
+            print("AssetManager: No unused assets to remove")
+            return (0, 0)
+
+        files_removed = 0
+        bytes_freed = 0
+
+        for asset_path in unused:
+            full_path = self.get_absolute_path(asset_path)
+
+            try:
+                file_size = os.path.getsize(full_path)
+            except OSError:
+                file_size = 0
+
+            try:
+                if os.path.exists(full_path):
+                    os.remove(full_path)
+                    files_removed += 1
+                    bytes_freed += file_size
+                    print(f"AssetManager: Removed unused asset {asset_path}")
+
+                # Clean up tracking
+                if asset_path in self.reference_counts:
+                    del self.reference_counts[asset_path]
+                if asset_path in self.asset_hashes:
+                    del self.asset_hashes[asset_path]
+
+            except Exception as e:
+                print(f"AssetManager: Error removing unused asset {asset_path}: {e}")
+
+        print(f"AssetManager: Removed {files_removed} unused assets, freed {bytes_freed} bytes")
+        return (files_removed, bytes_freed)
diff --git a/pyPhotoAlbum/mixins/operations/file_ops.py b/pyPhotoAlbum/mixins/operations/file_ops.py
index 02fafaf..7bc96a8 100644
--- a/pyPhotoAlbum/mixins/operations/file_ops.py
+++ b/pyPhotoAlbum/mixins/operations/file_ops.py
@@ -640,6 +640,165 @@ class FileOperationsMixin:
         else:
             self.show_status("PDF export failed to start", 3000)
 
+    @ribbon_action(label="Clean Assets", tooltip="Find and remove duplicate or unused image files", tab="Home", group="File")
+    def clean_assets(self):
+        """Find and remove duplicate and unused asset files to save space"""
+        from PyQt6.QtWidgets import QProgressDialog, QCheckBox
+        from PyQt6.QtCore import Qt
+
+        # Helper to format bytes
+        def format_bytes(num_bytes):
+            if num_bytes >= 1024 * 1024:
+                return f"{num_bytes / (1024 * 1024):.1f} MB"
+            elif num_bytes >= 1024:
+                return f"{num_bytes / 1024:.1f} KB"
+            else:
+                return f"{num_bytes} bytes"
+
+        # Scan for issues with progress dialog
+        progress = QProgressDialog("Scanning assets...", "Cancel", 0, 100, self)
+        progress.setWindowTitle("Clean Assets")
+        progress.setWindowModality(Qt.WindowModality.WindowModal)
+        progress.setValue(10)
+
+        # Compute hashes for duplicate detection
+        self.project.asset_manager.compute_all_hashes()
+        progress.setValue(40)
+
+        if progress.wasCanceled():
+            return
+
+        # Get duplicate stats
+        dup_groups, dup_files, dup_bytes = self.project.asset_manager.get_duplicate_stats()
+        progress.setValue(60)
+
+        # Get unused stats
+        unused_files, unused_bytes = self.project.asset_manager.get_unused_stats()
+        progress.setValue(80)
+
+        progress.close()
+
+        # Check if there's anything to clean
+        if dup_files == 0 and unused_files == 0:
+            QMessageBox.information(
+                self,
+                "Assets Clean",
+                "No duplicate or unused files were found in your project assets."
+            )
+            return
+
+        # Build dialog with checkboxes for each cleanup type
+        dialog = QDialog(self)
+        dialog.setWindowTitle("Clean Assets")
+        dialog.setMinimumWidth(450)
+
+        layout = QVBoxLayout()
+
+        # Info label
+        info_label = QLabel("Select which cleanup operations to perform:")
+        layout.addWidget(info_label)
+
+        # Duplicates checkbox
+        dup_checkbox = None
+        if dup_files > 0:
+            dup_checkbox = QCheckBox(
+                f"Remove {dup_files} duplicate file(s) in {dup_groups} group(s) "
+                f"(saves {format_bytes(dup_bytes)})"
+            )
+            dup_checkbox.setChecked(True)
+            dup_checkbox.setToolTip(
+                "Duplicate files have identical content but different names.\n"
+                "Image references will be automatically updated to use the kept file."
+            )
+            layout.addWidget(dup_checkbox)
+
+        # Unused checkbox
+        unused_checkbox = None
+        if unused_files > 0:
+            unused_checkbox = QCheckBox(
+                f"Remove {unused_files} unused file(s) (saves {format_bytes(unused_bytes)})"
+            )
+            unused_checkbox.setChecked(True)
+            unused_checkbox.setToolTip(
+                "Unused files exist in the assets folder but are not referenced\n"
+                "by any image element in your project."
+            )
+            layout.addWidget(unused_checkbox)
+
+        # Summary
+        total_files = dup_files + unused_files
+        total_bytes = dup_bytes + unused_bytes
+        summary_label = QLabel(f"\nTotal potential savings: {format_bytes(total_bytes)} from {total_files} file(s)")
+        summary_label.setStyleSheet("font-weight: bold;")
+        layout.addWidget(summary_label)
+
+        # Buttons
+        button_layout = QHBoxLayout()
+        cancel_btn = QPushButton("Cancel")
+        cancel_btn.clicked.connect(dialog.reject)
+        clean_btn = QPushButton("Clean Selected")
+        clean_btn.clicked.connect(dialog.accept)
+        clean_btn.setDefault(True)
+
+        button_layout.addStretch()
+        button_layout.addWidget(cancel_btn)
+        button_layout.addWidget(clean_btn)
+        layout.addLayout(button_layout)
+
+        dialog.setLayout(layout)
+
+        if dialog.exec() != QDialog.DialogCode.Accepted:
+            return
+
+        # Perform selected cleanups
+        total_removed = 0
+        total_saved = 0
+
+        # Remove duplicates if selected
+        if dup_checkbox and dup_checkbox.isChecked():
+            def update_image_references(old_path: str, new_path: str):
+                """Update all ImageData elements that reference the old path"""
+                from pyPhotoAlbum.models import ImageData
+
+                for page in self.project.pages:
+                    for element in page.layout.elements:
+                        if isinstance(element, ImageData) and element.image_path == old_path:
+                            element.image_path = new_path
+                            element.mark_modified()
+                            print(f"Updated image reference: {old_path} -> {new_path}")
+
+            removed, saved = self.project.asset_manager.deduplicate_assets(
+                update_references_callback=update_image_references
+            )
+            total_removed += removed
+            total_saved += saved
+
+        # Remove unused if selected
+        if unused_checkbox and unused_checkbox.isChecked():
+            removed, saved = self.project.asset_manager.remove_unused_assets()
+            total_removed += removed
+            total_saved += saved
+
+        if total_removed > 0:
+            # Mark project as dirty since we modified it
+            self.project.mark_dirty()
+
+            # Update view
+            self.update_view()
+
+            # Show result
+            QMessageBox.information(
+                self,
+                "Cleanup Complete",
+                f"Removed {total_removed} file(s).\n\n"
+                f"Saved {format_bytes(total_saved)} of disk space.\n\n"
+                f"Remember to save your project to preserve these changes."
+            )
+
+            self.show_status(f"Asset cleanup complete: removed {total_removed} files, saved {format_bytes(total_saved)}")
+        else:
+            self.show_status("No files were removed")
+
     @ribbon_action(label="About", tooltip="About pyPhotoAlbum and data format version", tab="Home", group="File")
     def show_about(self):
         """Show about dialog with version information"""
diff --git a/pyPhotoAlbum/thumbnail_browser.py b/pyPhotoAlbum/thumbnail_browser.py
index ede5993..3420aaf 100644
--- a/pyPhotoAlbum/thumbnail_browser.py
+++ b/pyPhotoAlbum/thumbnail_browser.py
@@ -835,6 +835,8 @@ class ThumbnailBrowserDock(QDockWidget):
 
     def _apply_sort(self):
         """Apply current sort mode to image files."""
+        if not hasattr(self.gl_widget, 'image_files') or not self.gl_widget.image_files:
+            return
         if self.current_sort == "name":
             # Sort by filename only (not full path)
             self.gl_widget.image_files.sort(key=lambda p: p.name.lower())
diff --git a/tests/test_asset_manager.py b/tests/test_asset_manager.py
new file mode 100644
index 0000000..a60905e
--- /dev/null
+++ b/tests/test_asset_manager.py
@@ -0,0 +1,469 @@
+"""
+Tests for AssetManager functionality including deduplication and unused asset detection
+"""
+
+import os
+import pytest
+import tempfile
+import shutil
+from PIL import Image
+
+from pyPhotoAlbum.asset_manager import AssetManager, compute_file_md5
+
+
+class TestComputeFileMd5:
+    """Tests for the compute_file_md5 function"""
+
+    def test_compute_md5_existing_file(self, tmp_path):
+        """Test MD5 computation for an existing file"""
+        # Create a test file
+        test_file = tmp_path / "test.txt"
+        test_file.write_text("Hello, World!")
+
+        md5_hash = compute_file_md5(str(test_file))
+        assert md5_hash is not None
+        # Known MD5 for "Hello, World!"
+        assert md5_hash == "65a8e27d8879283831b664bd8b7f0ad4"
+
+    def test_compute_md5_nonexistent_file(self):
+        """Test MD5 computation returns None for non-existent file"""
+        md5_hash = compute_file_md5("/nonexistent/path/file.txt")
+        assert md5_hash is None
+
+    def test_compute_md5_same_content_same_hash(self, tmp_path):
+        """Test that identical content produces identical hashes"""
+        content = b"Test content for hashing"
+
+        file1 = tmp_path / "file1.bin"
+        file2 = tmp_path / "file2.bin"
+        file1.write_bytes(content)
+        file2.write_bytes(content)
+
+        hash1 = compute_file_md5(str(file1))
+        hash2 = compute_file_md5(str(file2))
+
+        assert hash1 == hash2
+
+    def test_compute_md5_different_content_different_hash(self, tmp_path):
+        """Test that different content produces different hashes"""
+        file1 = tmp_path / "file1.txt"
+        file2 = tmp_path / "file2.txt"
+        file1.write_text("Content A")
+        file2.write_text("Content B")
+
+        hash1 = compute_file_md5(str(file1))
+        hash2 = compute_file_md5(str(file2))
+
+        assert hash1 != hash2
+
+
+class TestAssetManagerDeduplication:
+    """Tests for AssetManager deduplication methods"""
+
+    @pytest.fixture
+    def asset_manager(self, tmp_path):
+        """Create an AssetManager with a temporary project folder"""
+        project_folder = str(tmp_path / "test_project")
+        os.makedirs(project_folder)
+        return AssetManager(project_folder)
+
+    @pytest.fixture
+    def create_test_image(self):
+        """Factory fixture for creating test images"""
+        def _create(path, color="red", size=(100, 100)):
+            img = Image.new("RGB", size, color=color)
+            img.save(path)
+            return path
+        return _create
+
+    def test_compute_all_hashes_empty_folder(self, asset_manager):
+        """Test hash computation on empty assets folder"""
+        hashes = asset_manager.compute_all_hashes()
+        assert len(hashes) == 0
+
+    def test_compute_all_hashes_with_files(self, asset_manager, create_test_image):
+        """Test hash computation with files in assets folder"""
+        # Create some test images
+        img1 = os.path.join(asset_manager.assets_folder, "image1.png")
+        img2 = os.path.join(asset_manager.assets_folder, "image2.png")
+        create_test_image(img1, color="red")
+        create_test_image(img2, color="blue")
+
+        hashes = asset_manager.compute_all_hashes()
+
+        assert len(hashes) == 2
+        assert "assets/image1.png" in hashes
+        assert "assets/image2.png" in hashes
+
+    def test_find_duplicates_no_duplicates(self, asset_manager, create_test_image):
+        """Test finding duplicates when there are none"""
+        img1 = os.path.join(asset_manager.assets_folder, "image1.png")
+        img2 = os.path.join(asset_manager.assets_folder, "image2.png")
+        create_test_image(img1, color="red")
+        create_test_image(img2, color="blue")
+
+        duplicates = asset_manager.find_duplicates()
+        assert len(duplicates) == 0
+
+    def test_find_duplicates_with_duplicates(self, asset_manager, tmp_path):
+        """Test finding actual duplicate files"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (50, 50), color="green")
+        img.save(str(source_img))
+
+        # Copy the same image twice to assets folder
+        dup1 = os.path.join(asset_manager.assets_folder, "dup1.png")
+        dup2 = os.path.join(asset_manager.assets_folder, "dup2.png")
+        shutil.copy(str(source_img), dup1)
+        shutil.copy(str(source_img), dup2)
+
+        duplicates = asset_manager.find_duplicates()
+
+        assert len(duplicates) == 1  # One group of duplicates
+        # The group should contain both files
+        for paths in duplicates.values():
+            assert len(paths) == 2
+            assert "assets/dup1.png" in paths
+            assert "assets/dup2.png" in paths
+
+    def test_get_duplicate_stats_no_duplicates(self, asset_manager, create_test_image):
+        """Test duplicate stats when there are no duplicates"""
+        img1 = os.path.join(asset_manager.assets_folder, "image1.png")
+        create_test_image(img1, color="red")
+
+        groups, files, bytes_to_save = asset_manager.get_duplicate_stats()
+
+        assert groups == 0
+        assert files == 0
+        assert bytes_to_save == 0
+
+    def test_get_duplicate_stats_with_duplicates(self, asset_manager, tmp_path):
+        """Test duplicate stats with actual duplicates"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (100, 100), color="purple")
+        img.save(str(source_img))
+
+        # Copy to assets folder 3 times (creates 2 duplicates)
+        for i in range(3):
+            dest = os.path.join(asset_manager.assets_folder, f"image{i}.png")
+            shutil.copy(str(source_img), dest)
+
+        groups, files, bytes_to_save = asset_manager.get_duplicate_stats()
+
+        assert groups == 1  # One group
+        assert files == 2   # Two extra copies to remove
+        assert bytes_to_save > 0
+
+    def test_deduplicate_assets_removes_files(self, asset_manager, tmp_path):
+        """Test that deduplication actually removes duplicate files"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (50, 50), color="yellow")
+        img.save(str(source_img))
+
+        # Copy to assets folder 3 times
+        for i in range(3):
+            dest = os.path.join(asset_manager.assets_folder, f"image{i}.png")
+            shutil.copy(str(source_img), dest)
+            asset_manager.reference_counts[f"assets/image{i}.png"] = 1
+
+        # Count files before
+        files_before = len(os.listdir(asset_manager.assets_folder))
+        assert files_before == 3
+
+        # Run deduplication
+        files_removed, bytes_saved = asset_manager.deduplicate_assets()
+
+        # Check results
+        assert files_removed == 2
+        assert bytes_saved > 0
+
+        # Count files after
+        files_after = len(os.listdir(asset_manager.assets_folder))
+        assert files_after == 1
+
+    def test_deduplicate_assets_updates_callback(self, asset_manager, tmp_path):
+        """Test that deduplication calls the update callback correctly"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (50, 50), color="cyan")
+        img.save(str(source_img))
+
+        # Copy to assets folder
+        dest1 = os.path.join(asset_manager.assets_folder, "a_first.png")
+        dest2 = os.path.join(asset_manager.assets_folder, "b_second.png")
+        shutil.copy(str(source_img), dest1)
+        shutil.copy(str(source_img), dest2)
+
+        # Track callback invocations
+        callback_calls = []
+
+        def track_callback(old_path, new_path):
+            callback_calls.append((old_path, new_path))
+
+        # Run deduplication
+        asset_manager.deduplicate_assets(update_references_callback=track_callback)
+
+        # Callback should have been called for the duplicate
+        assert len(callback_calls) == 1
+        # b_second.png should be remapped to a_first.png (alphabetical order)
+        assert callback_calls[0] == ("assets/b_second.png", "assets/a_first.png")
+
+    def test_deduplicate_assets_transfers_reference_counts(self, asset_manager, tmp_path):
+        """Test that reference counts are properly transferred during deduplication"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (50, 50), color="magenta")
+        img.save(str(source_img))
+
+        # Copy to assets folder
+        dest1 = os.path.join(asset_manager.assets_folder, "a_first.png")
+        dest2 = os.path.join(asset_manager.assets_folder, "b_second.png")
+        shutil.copy(str(source_img), dest1)
+        shutil.copy(str(source_img), dest2)
+
+        # Set reference counts
+        asset_manager.reference_counts["assets/a_first.png"] = 2
+        asset_manager.reference_counts["assets/b_second.png"] = 3
+
+        # Run deduplication
+        asset_manager.deduplicate_assets()
+
+        # Check reference counts were merged
+        assert asset_manager.reference_counts.get("assets/a_first.png") == 5
+        assert "assets/b_second.png" not in asset_manager.reference_counts
+
+    def test_serialize_includes_hashes(self, asset_manager, create_test_image):
+        """Test that serialization includes asset hashes"""
+        img1 = os.path.join(asset_manager.assets_folder, "image1.png")
+        create_test_image(img1, color="red")
+        asset_manager.compute_all_hashes()
+
+        data = asset_manager.serialize()
+
+        assert "asset_hashes" in data
+        assert "assets/image1.png" in data["asset_hashes"]
+
+    def test_deserialize_restores_hashes(self, asset_manager):
+        """Test that deserialization restores asset hashes"""
+        test_data = {
+            "reference_counts": {"assets/test.png": 1},
+            "asset_hashes": {"assets/test.png": "abc123hash"}
+        }
+
+        asset_manager.deserialize(test_data)
+
+        assert asset_manager.asset_hashes.get("assets/test.png") == "abc123hash"
+
+    def test_compute_asset_hash_single_file(self, asset_manager, create_test_image):
+        """Test computing hash for a single asset"""
+        img_path = os.path.join(asset_manager.assets_folder, "single.png")
+        create_test_image(img_path, color="orange")
+
+        hash_result = asset_manager.compute_asset_hash("assets/single.png")
+
+        assert hash_result is not None
+        assert "assets/single.png" in asset_manager.asset_hashes
+        assert asset_manager.asset_hashes["assets/single.png"] == hash_result
+
+
+class TestAssetManagerIntegration:
+    """Integration tests for AssetManager with import and deduplication"""
+
+    @pytest.fixture
+    def asset_manager(self, tmp_path):
+        """Create an AssetManager with a temporary project folder"""
+        project_folder = str(tmp_path / "test_project")
+        os.makedirs(project_folder)
+        return AssetManager(project_folder)
+
+    def test_import_then_deduplicate(self, asset_manager, tmp_path):
+        """Test importing duplicate images and then deduplicating"""
+        # Create a source image
+        source_img = tmp_path / "source.png"
+        img = Image.new("RGB", (80, 80), color="navy")
+        img.save(str(source_img))
+
+        # Import the same image twice
+        path1 = asset_manager.import_asset(str(source_img))
+        path2 = asset_manager.import_asset(str(source_img))
+
+        assert path1 != path2  # Should have different names due to collision handling
+
+        # Check both files exist
+        assert os.path.exists(asset_manager.get_absolute_path(path1))
+        assert os.path.exists(asset_manager.get_absolute_path(path2))
+
+        # Find duplicates
+        duplicates = asset_manager.find_duplicates()
+        assert len(duplicates) == 1
+
+        # Deduplicate
+        files_removed, _ = asset_manager.deduplicate_assets()
+        assert files_removed == 1
+
+        # Only one file should remain
+        files_in_assets = os.listdir(asset_manager.assets_folder)
+        assert len(files_in_assets) == 1
+
+
+class TestAssetManagerUnused:
+    """Tests for AssetManager unused asset detection and removal"""
+
+    @pytest.fixture
+    def asset_manager(self, tmp_path):
+        """Create an AssetManager with a temporary project folder"""
+        project_folder = str(tmp_path / "test_project")
+        os.makedirs(project_folder)
+        return AssetManager(project_folder)
+
+    @pytest.fixture
+    def create_test_image(self):
+        """Factory fixture for creating test images"""
+        def _create(path, color="red", size=(100, 100)):
+            img = Image.new("RGB", size, color=color)
+            img.save(path)
+            return path
+        return _create
+
+    def test_find_unused_assets_empty_folder(self, asset_manager):
+        """Test finding unused assets in empty folder"""
+        unused = asset_manager.find_unused_assets()
+        assert len(unused) == 0
+
+    def test_find_unused_assets_all_referenced(self, asset_manager, create_test_image):
+        """Test finding unused assets when all are referenced"""
+        img1 = os.path.join(asset_manager.assets_folder, "image1.png")
+        img2 = os.path.join(asset_manager.assets_folder, "image2.png")
+        create_test_image(img1, color="red")
+        create_test_image(img2, color="blue")
+
+        # Add references for both
+        asset_manager.reference_counts["assets/image1.png"] = 1
+        asset_manager.reference_counts["assets/image2.png"] = 2
+
+        unused = asset_manager.find_unused_assets()
+        assert len(unused) == 0
+
+    def test_find_unused_assets_some_unreferenced(self, asset_manager, create_test_image):
+        """Test finding unused assets when some have no references"""
+        img1 = os.path.join(asset_manager.assets_folder, "used.png")
+        img2 = os.path.join(asset_manager.assets_folder, "unused.png")
+        create_test_image(img1, color="red")
+        create_test_image(img2, color="blue")
+
+        # Only reference one
+        asset_manager.reference_counts["assets/used.png"] = 1
+
+        unused = asset_manager.find_unused_assets()
+        assert len(unused) == 1
+        assert "assets/unused.png" in unused
+
+    def test_find_unused_assets_zero_reference_count(self, asset_manager, create_test_image):
+        """Test that zero reference count is considered unused"""
+        img = os.path.join(asset_manager.assets_folder, "orphan.png")
+        create_test_image(img, color="red")
+
+        # Set reference count to 0
+        asset_manager.reference_counts["assets/orphan.png"] = 0
+
+        unused = asset_manager.find_unused_assets()
+        assert len(unused) == 1
+        assert "assets/orphan.png" in unused
+
+    def test_get_unused_stats_no_unused(self, asset_manager, create_test_image):
+        """Test unused stats when all assets are referenced"""
+        img = os.path.join(asset_manager.assets_folder, "image.png")
+        create_test_image(img, color="red")
+        asset_manager.reference_counts["assets/image.png"] = 1
+
+        count, total_bytes = asset_manager.get_unused_stats()
+        assert count == 0
+        assert total_bytes == 0
+
+    def test_get_unused_stats_with_unused(self, asset_manager, create_test_image):
+        """Test unused stats with unreferenced files"""
+        img1 = os.path.join(asset_manager.assets_folder, "unused1.png")
+        img2 = os.path.join(asset_manager.assets_folder, "unused2.png")
+        create_test_image(img1, color="red")
+        create_test_image(img2, color="blue")
+
+        # No references for either file
+
+        count, total_bytes = asset_manager.get_unused_stats()
+        assert count == 2
+        assert total_bytes > 0
+
+    def test_remove_unused_assets_removes_files(self, asset_manager, create_test_image):
+        """Test that unused assets are actually removed"""
+        used_path = os.path.join(asset_manager.assets_folder, "used.png")
+        unused_path = os.path.join(asset_manager.assets_folder, "unused.png")
+        create_test_image(used_path, color="red")
+        create_test_image(unused_path, color="blue")
+
+        # Only reference the used file
+        asset_manager.reference_counts["assets/used.png"] = 1
+
+        # Remove unused
+        files_removed, bytes_freed = asset_manager.remove_unused_assets()
+
+        assert files_removed == 1
+        assert bytes_freed > 0
+
+        # Check files on disk
+        assert os.path.exists(used_path)
+        assert not os.path.exists(unused_path)
+
+    def test_remove_unused_assets_no_unused(self, asset_manager, create_test_image):
+        """Test removing unused when all assets are referenced"""
+        img = os.path.join(asset_manager.assets_folder, "used.png")
+        create_test_image(img, color="red")
+        asset_manager.reference_counts["assets/used.png"] = 1
+
+        files_removed, bytes_freed = asset_manager.remove_unused_assets()
+
+        assert files_removed == 0
+        assert bytes_freed == 0
+        assert os.path.exists(img)
+
+    def test_remove_unused_assets_cleans_tracking(self, asset_manager, create_test_image):
+        """Test that removing unused assets cleans up internal tracking"""
+        img = os.path.join(asset_manager.assets_folder, "orphan.png")
+        create_test_image(img, color="red")
+
+        # Set up tracking with zero refs and a hash
+        asset_manager.reference_counts["assets/orphan.png"] = 0
+        asset_manager.asset_hashes["assets/orphan.png"] = "somehash"
+
+        asset_manager.remove_unused_assets()
+
+        # Tracking should be cleaned up
+        assert "assets/orphan.png" not in asset_manager.reference_counts
+        assert "assets/orphan.png" not in asset_manager.asset_hashes
+
+    def test_remove_unused_preserves_referenced(self, asset_manager, create_test_image):
+        """Test that removing unused preserves all referenced assets"""
+        # Create several files
+        for i in range(5):
+            img = os.path.join(asset_manager.assets_folder, f"image{i}.png")
+            create_test_image(img, color="red")
+
+        # Reference only some of them
+        asset_manager.reference_counts["assets/image0.png"] = 1
+        asset_manager.reference_counts["assets/image2.png"] = 3
+        asset_manager.reference_counts["assets/image4.png"] = 1
+
+        files_removed, _ = asset_manager.remove_unused_assets()
+
+        assert files_removed == 2  # image1 and image3
+
+        # Check that referenced files still exist
+        assert os.path.exists(os.path.join(asset_manager.assets_folder, "image0.png"))
+        assert os.path.exists(os.path.join(asset_manager.assets_folder, "image2.png"))
+        assert os.path.exists(os.path.join(asset_manager.assets_folder, "image4.png"))
+
+        # Check that unreferenced files are gone
+        assert not os.path.exists(os.path.join(asset_manager.assets_folder, "image1.png"))
+        assert not os.path.exists(os.path.join(asset_manager.assets_folder, "image3.png"))