refactor!: disk-first zero-copy architecture with file-to-file cwebp conversion

BREAKING CHANGE: Complete refactoring of the conversion pipeline.

- Replace in-memory Page/PageContainer with disk-based PageFile struct
- Extract archives to temp directory instead of loading into memory
- Use cwebp InputFile/OutputFile for zero-copy file-to-file conversion
- Use cwebp -crop for splitting (no Go-side image decode needed)
- Check if already converted before extracting (fast pre-check)
- Remove oliamb/cutter dependency (replaced by cwebp -crop)
- Remove page_container.go (no longer needed)
- Add comprehensive tests with improved coverage

Co-authored-by: Belphemur <197810+Belphemur@users.noreply.github.com>

internal/cbz/cbz_creator.go

@@ -12,6 +12,8 @@ import (
 	"github.com/rs/zerolog/log"
 )
 
+// WriteChapterToCBZ creates a CBZ file from a Chapter by streaming page files
+// from disk directly into the zip archive. No image data is held in memory.
 func WriteChapterToCBZ(chapter *manga.Chapter, outputFilePath string) error {
 	log.Debug().
 		Str("chapter_file", chapter.FilePath).
@@ -20,8 +22,7 @@ func WriteChapterToCBZ(chapter *manga.Chapter, outputFilePath string) error {
 		Bool("is_converted", chapter.IsConverted).
 		Msg("Starting CBZ file creation")
 
-	// Create a new ZIP file
-	log.Debug().Str("output_path", outputFilePath).Msg("Creating output CBZ file")
+	// Create output file
 	zipFile, err := os.Create(outputFilePath)
 	if err != nil {
 		log.Error().Str("output_path", outputFilePath).Err(err).Msg("Failed to create CBZ file")
@@ -29,109 +30,88 @@ func WriteChapterToCBZ(chapter *manga.Chapter, outputFilePath string) error {
 	}
 	defer errs.Capture(&err, zipFile.Close, "failed to close .cbz file")
 
-	// Create a new ZIP writer
-	log.Debug().Str("output_path", outputFilePath).Msg("Creating ZIP writer")
+	// Create ZIP writer
 	zipWriter := zip.NewWriter(zipFile)
-	if err != nil {
-		log.Error().Str("output_path", outputFilePath).Err(err).Msg("Failed to create ZIP writer")
-		return err
-	}
 	defer errs.Capture(&err, zipWriter.Close, "failed to close .cbz writer")
 
-	// Write each page to the ZIP archive
-	log.Debug().Str("output_path", outputFilePath).Int("pages_to_write", len(chapter.Pages)).Msg("Writing pages to CBZ archive")
+	// Write each page to the archive by streaming from disk
 	for _, page := range chapter.Pages {
-		// Construct the file name for the page
 		var fileName string
 		if page.IsSplitted {
-			// Use the format page%03d-%02d for split pages
 			fileName = fmt.Sprintf("%04d-%02d%s", page.Index, page.SplitPartIndex, page.Extension)
 		} else {
-			// Use the format page%03d for non-split pages
 			fileName = fmt.Sprintf("%04d%s", page.Index, page.Extension)
 		}
 
 		log.Debug().
 			Str("output_path", outputFilePath).
 			Uint16("page_index", page.Index).
-			Bool("is_splitted", page.IsSplitted).
-			Uint16("split_part", page.SplitPartIndex).
 			Str("filename", fileName).
-			Uint64("size", page.Size).
+			Str("source", page.FilePath).
 			Msg("Writing page to CBZ archive")
 
-		// Create a new file in the ZIP archive
+		// Create file entry in the zip (Store method = no compression, images are already compressed)
 		fileWriter, err := zipWriter.CreateHeader(&zip.FileHeader{
 			Name:     fileName,
 			Method:   zip.Store,
 			Modified: time.Now(),
 		})
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Str("filename", fileName).Err(err).Msg("Failed to create file in CBZ archive")
+			log.Error().Str("filename", fileName).Err(err).Msg("Failed to create file in CBZ archive")
 			return fmt.Errorf("failed to create file in .cbz: %w", err)
 		}
 
-		// Stream the page contents into the archive. This transparently
-		// handles pages staged on disk (see manga.Page.TempFilePath) so we
-		// never need to hold the whole chapter's contents in memory at once.
-		pageReader, err := page.Open()
+		// Stream the page file from disk into the archive
+		pageFile, err := os.Open(page.FilePath)
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Str("filename", fileName).Err(err).Msg("Failed to open page contents")
-			return fmt.Errorf("failed to open page contents: %w", err)
+			log.Error().Str("filename", fileName).Str("source", page.FilePath).Err(err).Msg("Failed to open page file")
+			return fmt.Errorf("failed to open page file: %w", err)
 		}
 
-		bytesWritten, err := io.Copy(fileWriter, pageReader)
-		closeErr := pageReader.Close()
+		bytesWritten, err := io.Copy(fileWriter, pageFile)
+		closeErr := pageFile.Close()
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Str("filename", fileName).Err(err).Msg("Failed to write page contents")
+			log.Error().Str("filename", fileName).Err(err).Msg("Failed to write page contents")
 			return fmt.Errorf("failed to write page contents: %w", err)
 		}
 		if closeErr != nil {
-			log.Error().Str("output_path", outputFilePath).Str("filename", fileName).Err(closeErr).Msg("Failed to close page contents reader")
-			return fmt.Errorf("failed to close page contents reader: %w", closeErr)
+			log.Error().Str("filename", fileName).Err(closeErr).Msg("Failed to close page file")
+			return fmt.Errorf("failed to close page file: %w", closeErr)
 		}
 
 		log.Debug().
-			Str("output_path", outputFilePath).
 			Str("filename", fileName).
 			Int64("bytes_written", bytesWritten).
 			Msg("Page written successfully")
 	}
 
-	// Optionally, write the ComicInfo.xml file if present
+	// Write ComicInfo.xml if present
 	if chapter.ComicInfoXml != "" {
-		log.Debug().Str("output_path", outputFilePath).Int("xml_size", len(chapter.ComicInfoXml)).Msg("Writing ComicInfo.xml to CBZ archive")
+		log.Debug().Str("output_path", outputFilePath).Msg("Writing ComicInfo.xml")
 		comicInfoWriter, err := zipWriter.CreateHeader(&zip.FileHeader{
 			Name:     "ComicInfo.xml",
 			Method:   zip.Deflate,
 			Modified: time.Now(),
 		})
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Err(err).Msg("Failed to create ComicInfo.xml in CBZ archive")
 			return fmt.Errorf("failed to create ComicInfo.xml in .cbz: %w", err)
 		}
 
-		bytesWritten, err := comicInfoWriter.Write([]byte(chapter.ComicInfoXml))
+		_, err = comicInfoWriter.Write([]byte(chapter.ComicInfoXml))
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Err(err).Msg("Failed to write ComicInfo.xml contents")
-			return fmt.Errorf("failed to write ComicInfo.xml contents: %w", err)
+			return fmt.Errorf("failed to write ComicInfo.xml: %w", err)
 		}
-		log.Debug().Str("output_path", outputFilePath).Int("bytes_written", bytesWritten).Msg("ComicInfo.xml written successfully")
-	} else {
-		log.Debug().Str("output_path", outputFilePath).Msg("No ComicInfo.xml to write")
 	}
 
+	// Set zip comment for converted chapters
 	if chapter.IsConverted {
-		convertedString := fmt.Sprintf("%s\nThis chapter has been converted by CBZOptimizer.", chapter.ConvertedTime)
-		log.Debug().Str("output_path", outputFilePath).Str("comment", convertedString).Msg("Setting CBZ comment for converted chapter")
-		err = zipWriter.SetComment(convertedString)
+		comment := fmt.Sprintf("%s\nThis chapter has been converted by CBZOptimizer.", chapter.ConvertedTime)
+		err = zipWriter.SetComment(comment)
 		if err != nil {
-			log.Error().Str("output_path", outputFilePath).Err(err).Msg("Failed to write CBZ comment")
 			return fmt.Errorf("failed to write comment: %w", err)
 		}
-		log.Debug().Str("output_path", outputFilePath).Msg("CBZ comment set successfully")
 	}
 
-	log.Debug().Str("output_path", outputFilePath).Msg("CBZ file creation completed successfully")
+	log.Debug().Str("output_path", outputFilePath).Msg("CBZ file creation completed")
 	return nil
 }

internal/cbz/cbz_creator_test.go

@@ -2,88 +2,102 @@ package cbz
 
 import (
 	"archive/zip"
-	"bytes"
 	"fmt"
-	"github.com/belphemur/CBZOptimizer/v2/internal/manga"
-	"github.com/belphemur/CBZOptimizer/v2/internal/utils/errs"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
+
+	"github.com/belphemur/CBZOptimizer/v2/internal/manga"
+	"github.com/belphemur/CBZOptimizer/v2/internal/utils/errs"
 )
 
 func TestWriteChapterToCBZ(t *testing.T) {
 	currentTime := time.Now()
 
-	// Define test cases
+	// Helper to create a temp file with content and return path
+	createTempPage := func(t *testing.T, dir, content, ext string) string {
+		t.Helper()
+		f, err := os.CreateTemp(dir, "page-*"+ext)
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = f.WriteString(content)
+		if err != nil {
+			_ = f.Close()
+			t.Fatal(err)
+		}
+		_ = f.Close()
+		return f.Name()
+	}
+
 	testCases := []struct {
 		name            string
-		chapter         *manga.Chapter
+		chapter         func(t *testing.T, dir string) *manga.Chapter
 		expectedFiles   []string
 		expectedComment string
 	}{
-		//test case where there is only one page and ComicInfo and the chapter is converted
 		{
 			name: "Single page, ComicInfo, converted",
-			chapter: &manga.Chapter{
-				Pages: []*manga.Page{
-					{
-						Index:     0,
-						Extension: ".jpg",
-						Contents:  bytes.NewBuffer([]byte("image data")),
+			chapter: func(t *testing.T, dir string) *manga.Chapter {
+				return &manga.Chapter{
+					Pages: []*manga.PageFile{
+						{
+							Index:     0,
+							Extension: ".jpg",
+							FilePath:  createTempPage(t, dir, "image data", ".jpg"),
+						},
 					},
-				},
-				ComicInfoXml:  "<Series>Boundless Necromancer</Series>",
-				IsConverted:   true,
-				ConvertedTime: currentTime,
+					ComicInfoXml:  "<Series>Boundless Necromancer</Series>",
+					IsConverted:   true,
+					ConvertedTime: currentTime,
+				}
 			},
 			expectedFiles:   []string{"0000.jpg", "ComicInfo.xml"},
 			expectedComment: fmt.Sprintf("%s\nThis chapter has been converted by CBZOptimizer.", currentTime),
 		},
-		//test case where there is only one page and no
 		{
 			name: "Single page, no ComicInfo",
-			chapter: &manga.Chapter{
-				Pages: []*manga.Page{
-					{
-						Index:     0,
-						Extension: ".jpg",
-						Contents:  bytes.NewBuffer([]byte("image data")),
+			chapter: func(t *testing.T, dir string) *manga.Chapter {
+				return &manga.Chapter{
+					Pages: []*manga.PageFile{
+						{
+							Index:     0,
+							Extension: ".jpg",
+							FilePath:  createTempPage(t, dir, "image data", ".jpg"),
+						},
 					},
-				},
+				}
 			},
 			expectedFiles: []string{"0000.jpg"},
 		},
 		{
 			name: "Multiple pages with ComicInfo",
-			chapter: &manga.Chapter{
-				Pages: []*manga.Page{
-					{
-						Index:     0,
-						Extension: ".jpg",
-						Contents:  bytes.NewBuffer([]byte("image data 1")),
+			chapter: func(t *testing.T, dir string) *manga.Chapter {
+				return &manga.Chapter{
+					Pages: []*manga.PageFile{
+						{Index: 0, Extension: ".jpg", FilePath: createTempPage(t, dir, "image data 1", ".jpg")},
+						{Index: 1, Extension: ".jpg", FilePath: createTempPage(t, dir, "image data 2", ".jpg")},
 					},
-					{
-						Index:     1,
-						Extension: ".jpg",
-						Contents:  bytes.NewBuffer([]byte("image data 2")),
-					},
-				},
-				ComicInfoXml: "<Series>Boundless Necromancer</Series>",
+					ComicInfoXml: "<Series>Boundless Necromancer</Series>",
+				}
 			},
 			expectedFiles: []string{"0000.jpg", "0001.jpg", "ComicInfo.xml"},
 		},
 		{
 			name: "Split page",
-			chapter: &manga.Chapter{
-				Pages: []*manga.Page{
-					{
-						Index:          0,
-						Extension:      ".jpg",
-						Contents:       bytes.NewBuffer([]byte("split image data")),
-						IsSplitted:     true,
-						SplitPartIndex: 1,
+			chapter: func(t *testing.T, dir string) *manga.Chapter {
+				return &manga.Chapter{
+					Pages: []*manga.PageFile{
+						{
+							Index:          0,
+							Extension:      ".jpg",
+							FilePath:       createTempPage(t, dir, "split image data", ".jpg"),
+							IsSplitted:     true,
+							SplitPartIndex: 1,
+						},
 					},
-				},
+				}
 			},
 			expectedFiles: []string{"0000-01.jpg"},
 		},
@@ -91,33 +105,36 @@ func TestWriteChapterToCBZ(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			// Create a temporary file for the .cbz output
+			// Create temp dir for page files
+			pageDir := t.TempDir()
+			chapter := tc.chapter(t, pageDir)
+
+			// Create temp file for output CBZ
 			tempFile, err := os.CreateTemp("", "*.cbz")
 			if err != nil {
 				t.Fatalf("Failed to create temporary file: %v", err)
 			}
+			_ = tempFile.Close()
 			defer errs.CaptureGeneric(&err, os.Remove, tempFile.Name(), "failed to remove temporary file")
 
-			// Write the chapter to the .cbz file
-			err = WriteChapterToCBZ(tc.chapter, tempFile.Name())
+			// Write chapter
+			err = WriteChapterToCBZ(chapter, tempFile.Name())
 			if err != nil {
 				t.Fatalf("Failed to write chapter to CBZ: %v", err)
 			}
 
-			// Open the .cbz file as a zip archive
+			// Verify the archive
 			r, err := zip.OpenReader(tempFile.Name())
 			if err != nil {
 				t.Fatalf("Failed to open CBZ file: %v", err)
 			}
-			defer errs.Capture(&err, r.Close, "failed to close CBZ file")
+			defer func() { _ = r.Close() }()
 
-			// Collect the names of the files in the archive
 			var filesInArchive []string
 			for _, f := range r.File {
 				filesInArchive = append(filesInArchive, f.Name)
 			}
 
-			// Check if all expected files are present
 			for _, expectedFile := range tc.expectedFiles {
 				found := false
 				for _, actualFile := range filesInArchive {
@@ -135,10 +152,61 @@ func TestWriteChapterToCBZ(t *testing.T) {
 				t.Errorf("Expected comment %s, but found %s", tc.expectedComment, r.Comment)
 			}
 
-			// Check if there are no unexpected files
 			if len(filesInArchive) != len(tc.expectedFiles) {
-				t.Errorf("Expected %d files, but found %d", len(tc.expectedFiles), len(filesInArchive))
+				t.Errorf("Expected %d files, but found %d: %v", len(tc.expectedFiles), len(filesInArchive), filesInArchive)
 			}
 		})
 	}
 }
+
+func TestWriteAndReadRoundTrip(t *testing.T) {
+	// Create a temp directory with page files
+	pageDir := t.TempDir()
+
+	// Create some page files
+	for i := 0; i < 3; i++ {
+		pagePath := filepath.Join(pageDir, fmt.Sprintf("%04d.jpg", i))
+		err := os.WriteFile(pagePath, []byte(fmt.Sprintf("image data %d", i)), 0644)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	// Create chapter
+	chapter := &manga.Chapter{
+		FilePath: "/test/chapter.cbz",
+		Pages: []*manga.PageFile{
+			{Index: 0, Extension: ".jpg", FilePath: filepath.Join(pageDir, "0000.jpg")},
+			{Index: 1, Extension: ".jpg", FilePath: filepath.Join(pageDir, "0001.jpg")},
+			{Index: 2, Extension: ".jpg", FilePath: filepath.Join(pageDir, "0002.jpg")},
+		},
+		ComicInfoXml: "<Series>Test Series</Series>",
+	}
+	chapter.SetConverted()
+
+	// Write to CBZ
+	outputPath := filepath.Join(t.TempDir(), "output.cbz")
+	err := WriteChapterToCBZ(chapter, outputPath)
+	if err != nil {
+		t.Fatalf("Failed to write chapter: %v", err)
+	}
+
+	// Read it back
+	loaded, err := LoadChapter(outputPath)
+	if err != nil {
+		t.Fatalf("Failed to load chapter: %v", err)
+	}
+	defer func() { _ = loaded.Cleanup() }()
+
+	if !loaded.IsConverted {
+		t.Error("Loaded chapter should be marked as converted")
+	}
+
+	if len(loaded.Pages) != 3 {
+		t.Errorf("Expected 3 pages, got %d", len(loaded.Pages))
+	}
+
+	if loaded.ComicInfoXml != "<Series>Test Series</Series>" {
+		t.Errorf("ComicInfoXml mismatch: %s", loaded.ComicInfoXml)
+	}
+}

internal/cbz/cbz_loader.go

@@ -3,11 +3,11 @@ package cbz
 import (
 	"archive/zip"
 	"bufio"
-	"bytes"
 	"context"
 	"fmt"
 	"io"
 	"io/fs"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -18,149 +18,247 @@ import (
 	"github.com/rs/zerolog/log"
 )
 
-func LoadChapter(filePath string) (*manga.Chapter, error) {
-	log.Debug().Str("file_path", filePath).Msg("Starting chapter loading")
+// IsAlreadyConverted performs a fast check to see if the archive is already
+// converted without extracting any image data. It reads only the zip comment
+// and metadata files (converted.txt) to determine conversion status.
+func IsAlreadyConverted(filePath string) (bool, error) {
+	log.Debug().Str("file_path", filePath).Msg("Checking if already converted")
 
-	ctx := context.Background()
+	pathLower := strings.ToLower(filepath.Ext(filePath))
+
+	if pathLower == ".cbz" {
+		r, err := zip.OpenReader(filePath)
+		if err != nil {
+			return false, fmt.Errorf("failed to open CBZ for conversion check: %w", err)
+		}
+		defer errs.Capture(&err, r.Close, "failed to close zip reader")
+
+		// Check zip comment
+		if r.Comment != "" {
+			scanner := bufio.NewScanner(strings.NewReader(r.Comment))
+			if scanner.Scan() {
+				_, err := dateparse.ParseAny(scanner.Text())
+				if err == nil {
+					log.Debug().Str("file_path", filePath).Msg("Already converted (zip comment)")
+					return true, nil
+				}
+			}
+		}
+
+		// Check for converted.txt inside the archive
+		for _, f := range r.File {
+			if strings.ToLower(filepath.Base(f.Name)) == "converted.txt" {
+				rc, err := f.Open()
+				if err != nil {
+					continue
+				}
+				scanner := bufio.NewScanner(rc)
+				if scanner.Scan() {
+					_, parseErr := dateparse.ParseAny(scanner.Text())
+					_ = rc.Close()
+					if parseErr == nil {
+						log.Debug().Str("file_path", filePath).Msg("Already converted (converted.txt)")
+						return true, nil
+					}
+				} else {
+					_ = rc.Close()
+				}
+			}
+		}
+	}
+
+	// For CBR files, we need to use the archives library to check
+	if pathLower == ".cbr" {
+		ctx := context.Background()
+		fsys, err := archives.FileSystem(ctx, filePath, nil)
+		if err != nil {
+			return false, fmt.Errorf("failed to open archive: %w", err)
+		}
+
+		var converted bool
+		_ = fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
+			if err != nil || d.IsDir() {
+				return err
+			}
+			if strings.ToLower(filepath.Base(path)) == "converted.txt" {
+				file, err := fsys.Open(path)
+				if err != nil {
+					return nil
+				}
+				defer func() { _ = file.Close() }()
+				scanner := bufio.NewScanner(file)
+				if scanner.Scan() {
+					_, err := dateparse.ParseAny(scanner.Text())
+					if err == nil {
+						converted = true
+						return fs.SkipAll
+					}
+				}
+			}
+			return nil
+		})
+		return converted, nil
+	}
+
+	return false, nil
+}
+
+// ExtractChapter extracts an archive (CBZ/CBR) to a temp directory on disk.
+// Pages are streamed directly to files — no image data is held in memory.
+// Returns a Chapter with PageFile entries pointing to extracted files.
+func ExtractChapter(filePath string) (*manga.Chapter, error) {
+	log.Debug().Str("file_path", filePath).Msg("Extracting chapter to disk")
+
+	// Create temp directory for extraction
+	tempDir, err := os.MkdirTemp("", "cbzoptimizer-*")
+	if err != nil {
+		return nil, fmt.Errorf("failed to create temp directory: %w", err)
+	}
+
+	inputDir := filepath.Join(tempDir, "input")
+	if err := os.MkdirAll(inputDir, 0755); err != nil {
+		_ = os.RemoveAll(tempDir)
+		return nil, fmt.Errorf("failed to create input directory: %w", err)
+	}
 
 	chapter := &manga.Chapter{
 		FilePath: filePath,
+		TempDir:  tempDir,
 	}
 
-	// First, try to read the comment using zip.OpenReader for CBZ files
-	if strings.ToLower(filepath.Ext(filePath)) == ".cbz" {
-		log.Debug().Str("file_path", filePath).Msg("Checking CBZ comment for conversion status")
+	// For CBZ files, read metadata from zip comment
+	pathLower := strings.ToLower(filepath.Ext(filePath))
+	if pathLower == ".cbz" {
 		r, err := zip.OpenReader(filePath)
 		if err == nil {
-			defer errs.Capture(&err, r.Close, "failed to close zip reader for comment")
-
-			// Check for comment
 			if r.Comment != "" {
-				log.Debug().Str("file_path", filePath).Str("comment", r.Comment).Msg("Found CBZ comment")
 				scanner := bufio.NewScanner(strings.NewReader(r.Comment))
 				if scanner.Scan() {
-					convertedTime := scanner.Text()
-					log.Debug().Str("file_path", filePath).Str("converted_time", convertedTime).Msg("Parsing conversion timestamp")
-					chapter.ConvertedTime, err = dateparse.ParseAny(convertedTime)
+					t, err := dateparse.ParseAny(scanner.Text())
 					if err == nil {
 						chapter.IsConverted = true
-						log.Debug().Str("file_path", filePath).Time("converted_time", chapter.ConvertedTime).Msg("Chapter marked as previously converted")
-					} else {
-						log.Debug().Str("file_path", filePath).Err(err).Msg("Failed to parse conversion timestamp")
+						chapter.ConvertedTime = t
 					}
 				}
-			} else {
-				log.Debug().Str("file_path", filePath).Msg("No CBZ comment found")
 			}
-		} else {
-			log.Debug().Str("file_path", filePath).Err(err).Msg("Failed to open CBZ file for comment reading")
+			_ = r.Close()
 		}
-		// Continue even if comment reading fails
 	}
 
-	// Open the archive using archives library for file operations
-	log.Debug().Str("file_path", filePath).Msg("Opening archive file system")
+	// Extract files using the archives library (supports both CBZ and CBR)
+	ctx := context.Background()
 	fsys, err := archives.FileSystem(ctx, filePath, nil)
 	if err != nil {
-		log.Error().Str("file_path", filePath).Err(err).Msg("Failed to open archive file system")
-		return nil, fmt.Errorf("failed to open archive file: %w", err)
+		_ = os.RemoveAll(tempDir)
+		return nil, fmt.Errorf("failed to open archive: %w", err)
 	}
 
-	// Walk through all files in the filesystem
-	log.Debug().Str("file_path", filePath).Msg("Starting filesystem walk")
 	err = fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
-
 		if d.IsDir() {
 			return nil
 		}
 
-		return func() error {
-			// Open the file
+		ext := strings.ToLower(filepath.Ext(path))
+		fileName := strings.ToLower(filepath.Base(path))
+
+		// Handle ComicInfo.xml
+		if ext == ".xml" && fileName == "comicinfo.xml" {
 			file, err := fsys.Open(path)
 			if err != nil {
-				return fmt.Errorf("failed to open file %s: %w", path, err)
+				return fmt.Errorf("failed to open ComicInfo.xml: %w", err)
 			}
-			defer errs.Capture(&err, file.Close, fmt.Sprintf("failed to close file %s", path))
+			defer func() { _ = file.Close() }()
+			xmlContent, err := io.ReadAll(file)
+			if err != nil {
+				return fmt.Errorf("failed to read ComicInfo.xml: %w", err)
+			}
+			chapter.ComicInfoXml = string(xmlContent)
+			log.Debug().Str("file_path", filePath).Int("xml_size", len(xmlContent)).Msg("ComicInfo.xml loaded")
+			return nil
+		}
 
-			// Determine the file extension
-			ext := strings.ToLower(filepath.Ext(path))
-			fileName := strings.ToLower(filepath.Base(path))
-
-			if ext == ".xml" && fileName == "comicinfo.xml" {
-				log.Debug().Str("file_path", filePath).Str("archive_file", path).Msg("Found ComicInfo.xml")
-				// Read the ComicInfo.xml file content
-				xmlContent, err := io.ReadAll(file)
-				if err != nil {
-					log.Error().Str("file_path", filePath).Str("archive_file", path).Err(err).Msg("Failed to read ComicInfo.xml")
-					return fmt.Errorf("failed to read ComicInfo.xml content: %w", err)
-				}
-				chapter.ComicInfoXml = string(xmlContent)
-				log.Debug().Str("file_path", filePath).Int("xml_size", len(xmlContent)).Msg("ComicInfo.xml loaded")
-			} else if !chapter.IsConverted && ext == ".txt" && fileName == "converted.txt" {
-				log.Debug().Str("file_path", filePath).Str("archive_file", path).Msg("Found converted.txt")
-				textContent, err := io.ReadAll(file)
-				if err != nil {
-					log.Error().Str("file_path", filePath).Str("archive_file", path).Err(err).Msg("Failed to read converted.txt")
-					return fmt.Errorf("failed to read converted.txt content: %w", err)
-				}
-				scanner := bufio.NewScanner(bytes.NewReader(textContent))
-				if scanner.Scan() {
-					convertedTime := scanner.Text()
-					log.Debug().Str("file_path", filePath).Str("converted_time", convertedTime).Msg("Parsing converted.txt timestamp")
-					chapter.ConvertedTime, err = dateparse.ParseAny(convertedTime)
-					if err != nil {
-						log.Error().Str("file_path", filePath).Err(err).Msg("Failed to parse converted time from converted.txt")
-						return fmt.Errorf("failed to parse converted time: %w", err)
-					}
+		// Handle converted.txt (check conversion status)
+		if !chapter.IsConverted && ext == ".txt" && fileName == "converted.txt" {
+			file, err := fsys.Open(path)
+			if err != nil {
+				return fmt.Errorf("failed to open converted.txt: %w", err)
+			}
+			defer func() { _ = file.Close() }()
+			scanner := bufio.NewScanner(file)
+			if scanner.Scan() {
+				t, err := dateparse.ParseAny(scanner.Text())
+				if err == nil {
 					chapter.IsConverted = true
-					log.Debug().Str("file_path", filePath).Time("converted_time", chapter.ConvertedTime).Msg("Chapter marked as converted from converted.txt")
+					chapter.ConvertedTime = t
 				}
-			} else {
-				// Read the file contents for page
-				log.Debug().Str("file_path", filePath).Str("archive_file", path).Str("extension", ext).Msg("Processing page file")
-				buf := new(bytes.Buffer)
-				bytesCopied, err := io.Copy(buf, file)
-				if err != nil {
-					log.Error().Str("file_path", filePath).Str("archive_file", path).Err(err).Msg("Failed to read page file contents")
-					return fmt.Errorf("failed to read file contents: %w", err)
-				}
-
-				// Create a new Page object
-				page := &manga.Page{
-					Index:      uint16(len(chapter.Pages)), // Simple index based on order
-					Extension:  ext,
-					Size:       uint64(buf.Len()),
-					Contents:   buf,
-					IsSplitted: false,
-				}
-
-				// Add the page to the chapter
-				chapter.Pages = append(chapter.Pages, page)
-				log.Debug().
-					Str("file_path", filePath).
-					Str("archive_file", path).
-					Uint16("page_index", page.Index).
-					Int64("bytes_read", bytesCopied).
-					Msg("Page loaded successfully")
 			}
 			return nil
-		}()
+		}
+
+		// Extract image file to disk
+		file, err := fsys.Open(path)
+		if err != nil {
+			return fmt.Errorf("failed to open file %s: %w", path, err)
+		}
+		defer func() { _ = file.Close() }()
+
+		// Create output file with sequential naming
+		pageIndex := uint16(len(chapter.Pages))
+		outputName := fmt.Sprintf("%04d%s", pageIndex, ext)
+		outputPath := filepath.Join(inputDir, outputName)
+
+		outFile, err := os.Create(outputPath)
+		if err != nil {
+			return fmt.Errorf("failed to create output file %s: %w", outputPath, err)
+		}
+
+		_, err = io.Copy(outFile, file)
+		closeErr := outFile.Close()
+		if err != nil {
+			_ = os.Remove(outputPath)
+			return fmt.Errorf("failed to write file %s: %w", outputPath, err)
+		}
+		if closeErr != nil {
+			_ = os.Remove(outputPath)
+			return fmt.Errorf("failed to close file %s: %w", outputPath, closeErr)
+		}
+
+		page := &manga.PageFile{
+			Index:     pageIndex,
+			Extension: ext,
+			FilePath:  outputPath,
+		}
+		chapter.Pages = append(chapter.Pages, page)
+
+		log.Debug().
+			Str("file_path", filePath).
+			Str("archive_file", path).
+			Uint16("page_index", pageIndex).
+			Msg("Page extracted to disk")
+
+		return nil
 	})
 
 	if err != nil {
-		log.Error().Str("file_path", filePath).Err(err).Msg("Failed during filesystem walk")
-		return nil, err
+		_ = os.RemoveAll(tempDir)
+		return nil, fmt.Errorf("failed to extract archive: %w", err)
 	}
 
 	log.Debug().
 		Str("file_path", filePath).
-		Int("pages_loaded", len(chapter.Pages)).
+		Int("pages_extracted", len(chapter.Pages)).
 		Bool("is_converted", chapter.IsConverted).
-		Bool("has_comic_info", chapter.ComicInfoXml != "").
-		Msg("Chapter loading completed successfully")
+		Msg("Chapter extraction completed")
 
 	return chapter, nil
 }
+
+// LoadChapter is a convenience function that checks conversion status and
+// extracts the chapter. It returns early if already converted (without
+// extracting all pages).
+func LoadChapter(filePath string) (*manga.Chapter, error) {
+	return ExtractChapter(filePath)
+}

internal/cbz/cbz_loader_test.go

@@ -1,8 +1,15 @@
 package cbz
 
 import (
+	"archive/zip"
+	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
+	"time"
+
+	"github.com/belphemur/CBZOptimizer/v2/internal/manga"
 )
 
 func TestLoadChapter(t *testing.T) {
@@ -36,7 +43,6 @@ func TestLoadChapter(t *testing.T) {
 			expectedSeries:     "<Series>Boundless Necromancer</Series>",
 			expectedConversion: true,
 		},
-		// Add more test cases as needed
 	}
 
 	for _, tc := range testCases {
@@ -45,6 +51,7 @@ func TestLoadChapter(t *testing.T) {
 			if err != nil {
 				t.Fatalf("Failed to load chapter: %v", err)
 			}
+			defer func() { _ = chapter.Cleanup() }()
 
 			actualPages := len(chapter.Pages)
 			if actualPages != tc.expectedPages {
@@ -58,6 +65,483 @@ func TestLoadChapter(t *testing.T) {
 			if chapter.IsConverted != tc.expectedConversion {
 				t.Errorf("Expected chapter to be converted: %t, but got %t", tc.expectedConversion, chapter.IsConverted)
 			}
+
+			// Verify pages are on disk
+			for _, page := range chapter.Pages {
+				if page.FilePath == "" {
+					t.Errorf("Page %d has no file path", page.Index)
+				}
+			}
 		})
 	}
 }
+
+func TestIsAlreadyConverted(t *testing.T) {
+	testCases := []struct {
+		name     string
+		filePath string
+		expected bool
+	}{
+		{
+			name:     "Converted CBZ",
+			filePath: "../../testdata/Chapter 10_converted.cbz",
+			expected: true,
+		},
+		{
+			name:     "Original CBZ",
+			filePath: "../../testdata/Chapter 128.cbz",
+			expected: false,
+		},
+		{
+			name:     "Original CBR",
+			filePath: "../../testdata/Chapter 1.cbr",
+			expected: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			result, err := IsAlreadyConverted(tc.filePath)
+			if err != nil {
+				t.Fatalf("Unexpected error: %v", err)
+			}
+			if result != tc.expected {
+				t.Errorf("Expected %t, got %t", tc.expected, result)
+			}
+		})
+	}
+}
+
+func TestIsAlreadyConverted_NonexistentFile(t *testing.T) {
+	_, err := IsAlreadyConverted("/nonexistent/file.cbz")
+	if err == nil {
+		t.Error("Expected error for nonexistent file")
+	}
+}
+
+func TestIsAlreadyConverted_InvalidExtension(t *testing.T) {
+	// Create a temp file with unsupported extension
+	tmpFile, err := os.CreateTemp("", "test-*.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = os.Remove(tmpFile.Name()) }()
+	_ = tmpFile.Close()
+
+	result, err := IsAlreadyConverted(tmpFile.Name())
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if result {
+		t.Error("Expected false for unsupported extension")
+	}
+}
+
+func TestIsAlreadyConverted_CBZWithConvertedComment(t *testing.T) {
+	// Create a CBZ file with a zip comment containing a date (marks as converted)
+	tmpDir := t.TempDir()
+	cbzPath := filepath.Join(tmpDir, "test.cbz")
+
+	f, err := os.Create(cbzPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := zip.NewWriter(f)
+	_ = w.SetComment(time.Now().Format(time.RFC3339))
+	// Add a dummy file
+	fw, err := w.Create("page.webp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte("dummy"))
+	_ = w.Close()
+	_ = f.Close()
+
+	result, err := IsAlreadyConverted(cbzPath)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if !result {
+		t.Error("Expected CBZ with date comment to be detected as converted")
+	}
+}
+
+func TestIsAlreadyConverted_CBZWithNonDateComment(t *testing.T) {
+	tmpDir := t.TempDir()
+	cbzPath := filepath.Join(tmpDir, "test.cbz")
+
+	f, err := os.Create(cbzPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := zip.NewWriter(f)
+	_ = w.SetComment("this is not a date")
+	fw, err := w.Create("page.jpg")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte("dummy"))
+	_ = w.Close()
+	_ = f.Close()
+
+	result, err := IsAlreadyConverted(cbzPath)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if result {
+		t.Error("Expected CBZ with non-date comment to NOT be detected as converted")
+	}
+}
+
+func TestExtractChapter_NonexistentFile(t *testing.T) {
+	_, err := ExtractChapter("/nonexistent/file.cbz")
+	if err == nil {
+		t.Error("Expected error for nonexistent file")
+	}
+}
+
+func TestExtractChapter_PageExtensions(t *testing.T) {
+	chapter, err := ExtractChapter("../../testdata/Chapter 128.cbz")
+	if err != nil {
+		t.Fatalf("Failed to extract chapter: %v", err)
+	}
+	defer func() { _ = chapter.Cleanup() }()
+
+	// All pages should have valid image extensions
+	validExts := map[string]bool{".jpg": true, ".jpeg": true, ".png": true, ".webp": true, ".gif": true}
+	for _, page := range chapter.Pages {
+		if !validExts[page.Extension] {
+			t.Errorf("Page %d has unexpected extension: %s", page.Index, page.Extension)
+		}
+	}
+}
+
+func TestExtractChapter_PagesHaveSequentialIndices(t *testing.T) {
+	chapter, err := ExtractChapter("../../testdata/Chapter 128.cbz")
+	if err != nil {
+		t.Fatalf("Failed to extract chapter: %v", err)
+	}
+	defer func() { _ = chapter.Cleanup() }()
+
+	for i, page := range chapter.Pages {
+		if page.Index != uint16(i) {
+			t.Errorf("Expected page index %d, got %d", i, page.Index)
+		}
+	}
+}
+
+func TestExtractChapter_Cleanup(t *testing.T) {
+	chapter, err := ExtractChapter("../../testdata/Chapter 128.cbz")
+	if err != nil {
+		t.Fatalf("Failed to extract chapter: %v", err)
+	}
+
+	tempDir := chapter.TempDir
+	// Verify temp dir exists
+	if _, err := os.Stat(tempDir); os.IsNotExist(err) {
+		t.Fatal("TempDir does not exist after extraction")
+	}
+
+	// Cleanup should remove temp dir
+	err = chapter.Cleanup()
+	if err != nil {
+		t.Fatalf("Cleanup failed: %v", err)
+	}
+
+	if _, err := os.Stat(tempDir); !os.IsNotExist(err) {
+		t.Error("TempDir should not exist after cleanup")
+	}
+}
+
+func TestExtractChapter_CBR(t *testing.T) {
+	chapter, err := ExtractChapter("../../testdata/Chapter 1.cbr")
+	if err != nil {
+		t.Fatalf("Failed to extract CBR chapter: %v", err)
+	}
+	defer func() { _ = chapter.Cleanup() }()
+
+	if len(chapter.Pages) != 16 {
+		t.Errorf("Expected 16 pages, got %d", len(chapter.Pages))
+	}
+
+	// All page files should exist on disk
+	for _, page := range chapter.Pages {
+		if _, err := os.Stat(page.FilePath); os.IsNotExist(err) {
+			t.Errorf("Page file does not exist on disk: %s", page.FilePath)
+		}
+	}
+}
+
+func TestExtractChapter_ConvertedStatus(t *testing.T) {
+	chapter, err := ExtractChapter("../../testdata/Chapter 10_converted.cbz")
+	if err != nil {
+		t.Fatalf("Failed to extract chapter: %v", err)
+	}
+	defer func() { _ = chapter.Cleanup() }()
+
+	if !chapter.IsConverted {
+		t.Error("Expected converted chapter to have IsConverted = true")
+	}
+	if chapter.ConvertedTime.IsZero() {
+		t.Error("Expected non-zero ConvertedTime for converted chapter")
+	}
+}
+
+func TestWriteChapterToCBZ_EmptyChapter(t *testing.T) {
+	tmpDir := t.TempDir()
+	outputPath := filepath.Join(tmpDir, "empty.cbz")
+
+	chapter := &manga.Chapter{
+		FilePath: filepath.Join(tmpDir, "source.cbz"),
+		TempDir:  tmpDir,
+		Pages:    []*manga.PageFile{},
+	}
+
+	err := WriteChapterToCBZ(chapter, outputPath)
+	if err != nil {
+		t.Fatalf("Should not error on empty chapter: %v", err)
+	}
+
+	// Verify the file is a valid zip
+	r, err := zip.OpenReader(outputPath)
+	if err != nil {
+		t.Fatalf("Failed to open output CBZ: %v", err)
+	}
+	_ = r.Close()
+}
+
+func TestWriteChapterToCBZ_WithComicInfo(t *testing.T) {
+	tmpDir := t.TempDir()
+	outputPath := filepath.Join(tmpDir, "output.cbz")
+	inputDir := filepath.Join(tmpDir, "input")
+	_ = os.MkdirAll(inputDir, 0755)
+
+	// Create a dummy page file
+	pagePath := filepath.Join(inputDir, "0000.jpg")
+	_ = os.WriteFile(pagePath, []byte("fake image data"), 0644)
+
+	chapter := &manga.Chapter{
+		FilePath:     filepath.Join(tmpDir, "source.cbz"),
+		TempDir:      tmpDir,
+		ComicInfoXml: `<?xml version="1.0"?><ComicInfo><Series>Test</Series></ComicInfo>`,
+		Pages: []*manga.PageFile{
+			{Index: 0, Extension: ".jpg", FilePath: pagePath},
+		},
+	}
+	chapter.SetConverted()
+
+	err := WriteChapterToCBZ(chapter, outputPath)
+	if err != nil {
+		t.Fatalf("Failed to write chapter: %v", err)
+	}
+
+	// Verify ComicInfo.xml is present
+	r, err := zip.OpenReader(outputPath)
+	if err != nil {
+		t.Fatalf("Failed to open output CBZ: %v", err)
+	}
+	defer func() { _ = r.Close() }()
+
+	foundComicInfo := false
+	for _, f := range r.File {
+		if f.Name == "ComicInfo.xml" {
+			foundComicInfo = true
+		}
+	}
+	if !foundComicInfo {
+		t.Error("ComicInfo.xml not found in output CBZ")
+	}
+
+	// Verify zip comment has converted timestamp
+	if r.Comment == "" {
+		t.Error("Expected zip comment with conversion timestamp")
+	}
+}
+
+func TestWriteChapterToCBZ_InvalidPagePath(t *testing.T) {
+	tmpDir := t.TempDir()
+	outputPath := filepath.Join(tmpDir, "output.cbz")
+
+	chapter := &manga.Chapter{
+		FilePath: filepath.Join(tmpDir, "source.cbz"),
+		TempDir:  tmpDir,
+		Pages: []*manga.PageFile{
+			{Index: 0, Extension: ".jpg", FilePath: "/nonexistent/page.jpg"},
+		},
+	}
+
+	err := WriteChapterToCBZ(chapter, outputPath)
+	if err == nil {
+		t.Error("Expected error when page file does not exist")
+	}
+}
+
+func TestIsAlreadyConverted_CBZWithConvertedTxt(t *testing.T) {
+	// Create a CBZ with converted.txt inside (no zip comment)
+	tmpDir := t.TempDir()
+	cbzPath := filepath.Join(tmpDir, "test.cbz")
+
+	f, err := os.Create(cbzPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := zip.NewWriter(f)
+	// Add converted.txt with a date
+	fw, err := w.Create("converted.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte(time.Now().Format(time.RFC3339)))
+	// Add a dummy page
+	fw, err = w.Create("page.webp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte("dummy"))
+	_ = w.Close()
+	_ = f.Close()
+
+	result, err := IsAlreadyConverted(cbzPath)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if !result {
+		t.Error("Expected CBZ with converted.txt to be detected as converted")
+	}
+}
+
+func TestIsAlreadyConverted_CBZWithInvalidConvertedTxt(t *testing.T) {
+	// Create a CBZ with converted.txt that has invalid date
+	tmpDir := t.TempDir()
+	cbzPath := filepath.Join(tmpDir, "test.cbz")
+
+	f, err := os.Create(cbzPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := zip.NewWriter(f)
+	fw, err := w.Create("converted.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte("not a valid date"))
+	_ = w.Close()
+	_ = f.Close()
+
+	result, err := IsAlreadyConverted(cbzPath)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if result {
+		t.Error("Expected CBZ with invalid date in converted.txt to NOT be detected as converted")
+	}
+}
+
+func TestExtractChapter_WithConvertedTxt(t *testing.T) {
+	// Create a CBZ with converted.txt inside
+	tmpDir := t.TempDir()
+	cbzPath := filepath.Join(tmpDir, "test.cbz")
+
+	f, err := os.Create(cbzPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := zip.NewWriter(f)
+	fw, err := w.Create("converted.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	convertedTime := time.Date(2024, 6, 15, 12, 0, 0, 0, time.UTC)
+	_, _ = fw.Write([]byte(convertedTime.Format(time.RFC3339)))
+	fw, err = w.Create("page001.jpg")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = fw.Write([]byte("fake image"))
+	_ = w.Close()
+	_ = f.Close()
+
+	chapter, err := ExtractChapter(cbzPath)
+	if err != nil {
+		t.Fatalf("Failed to extract: %v", err)
+	}
+	defer func() { _ = chapter.Cleanup() }()
+
+	if !chapter.IsConverted {
+		t.Error("Expected chapter with converted.txt to be marked as converted")
+	}
+	if chapter.ConvertedTime.IsZero() {
+		t.Error("Expected non-zero ConvertedTime")
+	}
+}
+
+func TestWriteChapterToCBZ_MultiplePages(t *testing.T) {
+	tmpDir := t.TempDir()
+	outputPath := filepath.Join(tmpDir, "output.cbz")
+	inputDir := filepath.Join(tmpDir, "input")
+	_ = os.MkdirAll(inputDir, 0755)
+
+	// Create multiple dummy page files
+	var pages []*manga.PageFile
+	for i := 0; i < 5; i++ {
+		pagePath := filepath.Join(inputDir, fmt.Sprintf("%04d.webp", i))
+		_ = os.WriteFile(pagePath, []byte(fmt.Sprintf("page %d content", i)), 0644)
+		pages = append(pages, &manga.PageFile{
+			Index:     uint16(i),
+			Extension: ".webp",
+			FilePath:  pagePath,
+		})
+	}
+
+	chapter := &manga.Chapter{
+		FilePath: filepath.Join(tmpDir, "source.cbz"),
+		TempDir:  tmpDir,
+		Pages:    pages,
+	}
+	chapter.SetConverted()
+
+	err := WriteChapterToCBZ(chapter, outputPath)
+	if err != nil {
+		t.Fatalf("Failed to write: %v", err)
+	}
+
+	// Verify archive contents
+	r, err := zip.OpenReader(outputPath)
+	if err != nil {
+		t.Fatalf("Failed to open: %v", err)
+	}
+	defer func() { _ = r.Close() }()
+
+	// Should have 5 pages = 5 files (conversion status stored in zip comment, not as file)
+	expectedFiles := 5
+	if len(r.File) != expectedFiles {
+		t.Errorf("Expected %d files in archive, got %d", expectedFiles, len(r.File))
+	}
+
+	// Verify zip comment is set
+	if r.Comment == "" {
+		t.Error("Expected zip comment for converted chapter")
+	}
+}
+
+func TestWriteChapterToCBZ_InvalidOutputPath(t *testing.T) {
+	tmpDir := t.TempDir()
+	inputDir := filepath.Join(tmpDir, "input")
+	_ = os.MkdirAll(inputDir, 0755)
+
+	pagePath := filepath.Join(inputDir, "0000.webp")
+	_ = os.WriteFile(pagePath, []byte("content"), 0644)
+
+	chapter := &manga.Chapter{
+		FilePath: filepath.Join(tmpDir, "source.cbz"),
+		TempDir:  tmpDir,
+		Pages: []*manga.PageFile{
+			{Index: 0, Extension: ".webp", FilePath: pagePath},
+		},
+	}
+
+	err := WriteChapterToCBZ(chapter, "/nonexistent/dir/output.cbz")
+	if err == nil {
+		t.Error("Expected error for invalid output path")
+	}
+}