fix: add missing keyboard metrics to Lyra3CoversTheme (#1101)

Fix for keyboard. Issue #1100

.gitignore

@@ -3,6 +3,7 @@
 .DS_Store
 .vscode
 lib/EpdFont/fontsrc
+lib/I18n/I18nStrings.cpp
 *.generated.h
 .vs
 build

README.md

@@ -51,7 +51,7 @@ For more details about the scope of the project, see the [SCOPE.md](SCOPE.md) do
 
 ### Web (latest firmware)
 
-1. Connect your Xteink X4 to your computer via USB-C
+1. Connect your Xteink X4 to your computer via USB-C and wake/unlock the device
 2. Go to https://xteink.dve.al/ and click "Flash CrossPoint firmware"
 
 To revert back to the official firmware, you can flash the latest official firmware from https://xteink.dve.al/, or swap

SCOPE.md

@@ -25,6 +25,8 @@ usability over "swiss-army-knife" functionality.
 * **Library Management:** E.g. Simple, intuitive ways to organize and navigate a collection of books.
 * **Local Transfer:** E.g. Simple, "pull" based book loading via a basic web-server or public and widely-used standards.
 * **Language Support:** E.g. Support for multiple languages both in the reader and in the interfaces.
+* **Reference Tools:** E.g. Local dictionary lookup. Providing quick, offline definitions to enhance comprehension 
+  without breaking focus.
 
 ### Out-of-Scope
 
@@ -34,8 +36,8 @@ usability over "swiss-army-knife" functionality.
 * **Active Connectivity:** No RSS readers, News aggregators, or Web browsers. Background Wi-Fi tasks drain the battery
   and complicate the single-core CPU's execution.
 * **Media Playback:** No Audio players or Audio-books.
-* **Complex Reader Features:** No highlighting, notes, or dictionary lookup. These features are better suited for
-  devices with better input capabilities and more powerful chips.
+* **Complex Annotation:** No typed out notes. These features are better suited for devices with better input
+  capabilities and more powerful chips.
 
 ## 3. Idea Evaluation
 

bin/clang-format-fix

@@ -1,10 +1,18 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+# Check if clang-format is availible
+command -v clang-format >/dev/null 2>&1 || {
+    printf "'clang-format' not found in current environment\n"
+    printf "install 'clang', 'clang-tools', or 'clang-format' depending on your distro/os and tooling requirements\n"
+    exit 1
+}
 
 GIT_LS_FILES_FLAGS=""
 if [[ "$1" == "-g" ]]; then
   GIT_LS_FILES_FLAGS="--modified"
 fi
 
+
 # --- Main Logic ---
 
 # Format all files (or only modified files if -g is passed)
@@ -18,4 +26,5 @@ git ls-files  --exclude-standard ${GIT_LS_FILES_FLAGS} \
     | grep -E '\.(c|cpp|h|hpp)$' \
     | grep -v -E '^lib/EpdFont/builtinFonts/' \
     | grep -v -E '^lib/Epub/Epub/hyphenation/generated/' \
+    | grep -v -E '^lib/uzlib/' \
     | xargs -r clang-format -style=file -i

docs/hyphenation-trie-format.md

@@ -45,22 +45,9 @@ byte arrays, and emits headers under
 `SerializedHyphenationPatterns` descriptor so the reader can keep the automaton
 in flash.
 
-To refresh the firmware assets after updating the `.bin` files, run:
+A convenient script `update_hyphenation.sh` is used to update all languages.
+To use it, run:
 
-```
-./scripts/generate_hyphenation_trie.py \
-    --input lib/Epub/Epub/hyphenation/tries/en.bin \
-    --output lib/Epub/Epub/hyphenation/generated/hyph-en.trie.h
-
-./scripts/generate_hyphenation_trie.py \
-    --input lib/Epub/Epub/hyphenation/tries/fr.bin \
-    --output lib/Epub/Epub/hyphenation/generated/hyph-fr.trie.h
-
-./scripts/generate_hyphenation_trie.py \
-    --input lib/Epub/Epub/hyphenation/tries/de.bin \
-    --output lib/Epub/Epub/hyphenation/generated/hyph-de.trie.h
-
-./scripts/generate_hyphenation_trie.py \
-    --input lib/Epub/Epub/hyphenation/tries/ru.bin \
-    --output lib/Epub/Epub/hyphenation/generated/hyph-ru.trie.h
+```sh
+./scripts/update_hypenation.sh
 ```

docs/i18n.md

@@ -0,0 +1,237 @@
+# Internationalization (I18N)
+
+This guide explains the multi-language support system in CrossPoint Reader.
+
+## Supported Languages
+
+- English
+- French
+- German
+- Portuguese
+- Spanish
+- Swedish
+- Czech
+- Russian
+
+---
+
+
+## For Developers
+
+### Translation System Architecture
+
+The I18N system uses **per-language YAML files** to maintain translations and a Python script to generate C++ code:
+
+```
+lib/I18n/
+├── translations/                # One YAML file per language
+│   ├── english.yaml
+│   ├── spanish.yaml
+│   ├── french.yaml
+│   └── ...
+├── I18n.h
+├── I18n.cpp
+├── I18nKeys.h                   # Enums (auto-generated)
+├── I18nStrings.h                # String array declarations (auto-generated)
+└── I18nStrings.cpp              # String array definitions (auto-generated)
+
+scripts/
+└── gen_i18n.py                  # Code generator script
+```
+
+**Key principle:** All translations are managed in the YAML files under `lib/I18n/translations/`. The Python script generates the necessary C++ code automatically.
+
+---
+
+### YAML File Format
+
+Each language has its own file in `lib/I18n/translations/` (e.g. `spanish.yaml`).
+
+A file looks like this:
+
+```yaml
+_language_name: "Español"
+_language_code: "SPANISH"
+_order: "1"
+
+STR_CROSSPOINT: "CrossPoint"
+STR_BOOTING: "BOOTING"
+STR_BROWSE_FILES: "Buscar archivos"
+```
+
+**Metadata keys** (prefixed with `_`):
+- `_language_name` — Native display name shown to the user (e.g. "Français")
+- `_language_code` — C++ enum name (e.g. "FRENCH"). Must be a valid C++ identifier.
+- `_order` — Controls the position in the Language enum (English is always 0)
+
+**Rules:**
+- Use UTF-8 encoding
+- Every line must follow the format: `KEY: "value"`
+- Keys must be valid C++ identifiers (uppercase, strats with STR_)
+- Keys must be unique within a file
+- String values must be quoted
+- Use `\n` for newlines, `\\` for literal backslashes, `\"` for literal quotes inside values
+
+---
+
+### Adding New Strings
+
+To add a new translatable string:
+
+#### 1. Edit the English YAML file
+
+Add the key to `lib/I18n/translations/english.yaml`:
+
+```yaml
+STR_MY_NEW_STRING: "My New String"
+```
+
+Then add translations in each language file. If a key is missing from a
+language file, the generator will automatically use the English text as a
+fallback (and print a warning).
+
+#### 2. Run the generator script
+
+```bash
+python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/
+```
+
+This automatically:
+- Fills missing translations from English
+- Updates the `StrId` enum in `I18nKeys.h`
+- Regenerates all language arrays in `I18nStrings.cpp`
+
+#### 3. Use in code
+
+```cpp
+#include <I18n.h>
+
+// Using the tr() macro (recommended)
+renderer.drawText(font, x, y, tr(STR_MY_NEW_STRING));
+
+// Using I18N.get() directly
+const char* text = I18N.get(StrId::STR_MY_NEW_STRING);
+```
+
+**That's it!** No manual array synchronization needed.
+
+---
+
+### Adding a New Language
+
+To add support for a new language (e.g., Italian):
+
+#### 1. Create a new YAML file
+
+Create `lib/I18n/translations/italian.yaml`:
+
+```yaml
+_language_name: "Italiano"
+_language_code: "ITALIAN"
+_order: "7"
+
+STR_CROSSPOINT: "CrossPoint"
+STR_BOOTING: "AVVIO"
+```
+
+You only need to include the strings you have translations for. Missing
+keys will fall back to English automatically.
+
+#### 2. Run the generator
+
+```bash
+python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/
+```
+
+This automatically updates all necessary code.
+
+---
+
+### Modifying Existing Translations
+
+Simply edit the relevant YAML file and regenerate:
+
+```bash
+python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/
+```
+
+---
+
+### UTF-8 Encoding
+
+The YAML files use UTF-8 encoding. Special characters are automatically converted to C++ UTF-8 hex sequences by the generator.
+
+---
+
+### I18N API Reference
+
+```cpp
+// === Convenience Macros (Recommended) ===
+
+// tr(id) - Get translated string without StrId:: prefix
+const char* text = tr(STR_SETTINGS_TITLE);
+renderer.drawText(font, x, y, tr(STR_BROWSE_FILES));
+Serial.printf("Status: %s\n", tr(STR_CONNECTED));
+
+// I18N - Shorthand for I18n::getInstance()
+I18N.setLanguage(Language::SPANISH);
+Language lang = I18N.getLanguage();
+
+// === Full API ===
+
+// Get the singleton instance
+I18n& instance = I18n::getInstance();
+
+// Get translated string (three equivalent ways)
+const char* text = tr(STR_SETTINGS_TITLE);              // Macro (recommended)
+const char* text = I18N.get(StrId::STR_SETTINGS_TITLE);   // Direct call
+const char* text = I18N[StrId::STR_SETTINGS_TITLE];       // Operator overload
+
+// Set language
+I18N.setLanguage(Language::SPANISH);
+
+// Get current language
+Language lang = I18N.getLanguage();
+
+// Save language setting to file
+I18N.saveSettings();
+
+// Load language setting from file
+I18N.loadSettings();
+
+// Get character set for font subsetting (static method)
+const char* chars = I18n::getCharacterSet(Language::FRENCH);
+```
+
+---
+
+## File Storage
+
+Language settings are stored in:
+```
+/.crosspoint/language.bin
+```
+
+This file contains:
+- Version byte
+- Current language selection (1 byte)
+
+---
+
+## Translation Workflow
+
+### For Developers (Adding Features)
+
+1. Add new strings to `lib/I18n/translations/english.yaml`
+2. Run `python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/`
+3. Use the new `StrId` in your code
+4. Request translations from translators
+
+### For Translators
+
+1. Open the YAML file for your language in `lib/I18n/translations/`
+2. Add or update translations using the format `STR_KEY: "translated text"`
+3. Keep translations concise (E-ink space constraints)
+4. Make sure the file is in UTF-8 encoding
+5. Run `python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/` to verify
+6. Test on device or submit for review

docs/translators.md

@@ -0,0 +1,36 @@
+# Translators
+
+Below is a list of users and languages CrossPoint may support in the future. 
+Note because a language is below does not mean there is official support for the language at this time.
+
+## Contributing
+
+If you'd like to add your name to this list, please open a PR adding yourself and your Github link. Thank you!
+
+## French
+- [Spigaw](https://github.com/Spigaw)
+- [CaptainFrito](https://github.com/CaptainFrito)
+
+## German
+- [DavidOrtmann](https://github.com/DavidOrtmann)
+
+## Czech
+- [brbla](https://github.com/brbla)
+
+## Portuguese (Brazil)
+- [yagofarias](https://github.com/yagofarias)
+
+## Italian
+- [fragolinux](https://github.com/fragolinux)
+
+## Russian
+- [madebyKir](https://github.com/madebyKir)
+- [mrtnvgr](https://github.com/mrtnvgr)
+
+## Spanish
+- [yeyeto2788](https://github.com/yeyeto2788)
+- [Skrzakk](https://github.com/Skrzakk)
+- [pablohc](https://github.com/pablohc)
+
+## Swedish
+- [dawiik](https://github.com/dawiik)

docs/webserver.md

@@ -1,14 +1,14 @@
 # Web Server Guide
 
-This guide explains how to connect your CrossPoint Reader to WiFi and use the built-in web server to upload EPUB files from your computer or phone.
+This guide explains how to connect your CrossPoint Reader to WiFi and use the built-in web server to upload files from your computer or phone.
 
 ## Overview
 
 CrossPoint Reader includes a built-in web server that allows you to:
 
-- Upload EPUB files wirelessly from any device on the same WiFi network
+- Upload files wirelessly from any device on the same WiFi network
 - Browse and manage files on your device's SD card
-- Create folders to organize your ebooks
+- Create folders to organize your library
 - Delete files and folders
 
 ## Prerequisites
@@ -129,34 +129,31 @@ Click **File Manager** to access file management features.
 #### Browsing Files
 
 - The file manager displays all files and folders on your SD card
-- **Folders** are highlighted in yellow with a 📁 icon
-- **EPUB files** are highlighted in green with a 📗 icon
+- **Folders** are highlighted in yellow and indicated with a 📁 icon
+- **EPUB Files** are highlighted in green and indicated with a 📗 icon
+- **All Other Files** are not highlighted and indicated with a 📄 icon
 - Click on a folder name to navigate into it
 - Use the breadcrumb navigation at the top to go back to parent folders
 
 <img src="./images/wifi/webserver_files.png" width="600">
 
-#### Uploading EPUB Files
+#### Uploading Files
 
-1. Click the **+ Add** button in the top-right corner
-2. Select **Upload eBook** from the dropdown menu
-3. Click **Choose File** and select an `.epub` file from your device
-4. Click **Upload**
-5. A progress bar will show the upload status
-6. The page will automatically refresh when the upload is complete
-
-**Note:** Only `.epub` files are accepted. Other file types will be rejected.
+1. Click the **📤 Upload** button in the top-right corner
+2. Click **Choose File** and select a file from your device
+3. Click **Upload**
+4. A progress bar will show the upload status
+5. The page will automatically refresh when the upload is complete
 
 <img src="./images/wifi/webserver_upload.png" width="600">
 
 #### Creating Folders
 
-1. Click the **+ Add** button in the top-right corner
-2. Select **New Folder** from the dropdown menu
-3. Enter a folder name (must not contain characters \" * : < > ? / \\ | and must not be . or ..)
-4. Click **Create Folder**
+1. Click the **📁 New Folder** button in the top-right corner
+2. Enter a folder name (must not contain characters \" * : < > ? / \\ | and must not be . or ..)
+3. Click **Create Folder**
 
-This is useful for organizing your ebooks by genre, author, or series.
+This is useful for organizing your library by genre, author, series or file type.
 
 #### Deleting Files and Folders
 
@@ -168,11 +165,25 @@ This is useful for organizing your ebooks by genre, author, or series.
 
 **Note:** Folders must be empty before they can be deleted.
 
+#### Moving Files
+
+1. Click the **📂** (folder) icon next to any file
+2. Enter a folder name or select one from the dropdown
+3. Click **Move** to relocate the file
+
+**Note:** Typing in a nonexistent folder name will result in the following error: "Failed to move: Destination not found"
+
+#### Renaming Files
+
+1. Click the **✏️** (pencil) icon next to any file
+2. Enter a file name (must not contain characters \" * : < > ? / \\ | and must not be . or ..)
+3. Click **Rename** to permanently rename the file
+
 ---
 
 ## Command Line File Management
 
-For power users, you can manage files directly from your terminal using `curl` while the device is in File Upload mode a detailed documentation can be found [here](./webserver-endpoints.md). 
+For power users, you can manage files directly from your terminal using `curl` while the device is in File Upload mode. Detailed documentation can be found [here](./webserver-endpoints.md). 
 
 ## Security Notes
 
@@ -189,7 +200,6 @@ For power users, you can manage files directly from your terminal using `curl` w
 - **Supported WiFi:** 2.4GHz networks (802.11 b/g/n)
 - **Web Server Port:** 80 (HTTP)
 - **Maximum Upload Size:** Limited by available SD card space
-- **Supported File Format:** `.epub` only
 - **Browser Compatibility:** All modern browsers (Chrome, Firefox, Safari, Edge)
 
 ---
@@ -198,7 +208,7 @@ For power users, you can manage files directly from your terminal using `curl` w
 
 1. **Organize with folders** - Create folders before uploading to keep your library organized
 2. **Check signal strength** - Stronger signals (`|||` or `||||`) provide faster, more reliable uploads
-3. **Upload multiple files** - You can upload files one at a time; the page refreshes after each upload
+3. **Upload multiple files** - You can select and upload multiple files at once; the manager will queue them and refresh when the batch is finished
 4. **Use descriptive names** - Name your folders clearly (e.g., "SciFi", "Mystery", "Non-Fiction")
 5. **Keep credentials saved** - Save your WiFi password for quick reconnection in the future
 6. **Exit when done** - Press **Back** to exit the WiFi screen and save battery

lib/EpdFont/EpdFont.cpp

@@ -17,6 +17,11 @@ void EpdFont::getTextBounds(const char* string, const int startX, const int star
 
   int cursorX = startX;
   const int cursorY = startY;
+  int lastBaseX = startX;
+  int lastBaseAdvance = 0;
+  int lastBaseTop = 0;
+  bool hasBaseGlyph = false;
+  constexpr int MIN_COMBINING_GAP_PX = 1;
   uint32_t cp;
   while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&string)))) {
     const EpdGlyph* glyph = getGlyph(cp);
@@ -30,11 +35,30 @@ void EpdFont::getTextBounds(const char* string, const int startX, const int star
       continue;
     }
 
-    *minX = std::min(*minX, cursorX + glyph->left);
-    *maxX = std::max(*maxX, cursorX + glyph->left + glyph->width);
-    *minY = std::min(*minY, cursorY + glyph->top - glyph->height);
-    *maxY = std::max(*maxY, cursorY + glyph->top);
-    cursorX += glyph->advanceX;
+    const bool isCombining = utf8IsCombiningMark(cp);
+    int raiseBy = 0;
+    if (isCombining && hasBaseGlyph) {
+      const int currentGap = glyph->top - glyph->height - lastBaseTop;
+      if (currentGap < MIN_COMBINING_GAP_PX) {
+        raiseBy = MIN_COMBINING_GAP_PX - currentGap;
+      }
+    }
+
+    const int glyphBaseX = (isCombining && hasBaseGlyph) ? (lastBaseX + lastBaseAdvance / 2) : cursorX;
+    const int glyphBaseY = cursorY - raiseBy;
+
+    *minX = std::min(*minX, glyphBaseX + glyph->left);
+    *maxX = std::max(*maxX, glyphBaseX + glyph->left + glyph->width);
+    *minY = std::min(*minY, glyphBaseY + glyph->top - glyph->height);
+    *maxY = std::max(*maxY, glyphBaseY + glyph->top);
+
+    if (!isCombining) {
+      lastBaseX = cursorX;
+      lastBaseAdvance = glyph->advanceX;
+      lastBaseTop = glyph->top;
+      hasBaseGlyph = true;
+      cursorX += glyph->advanceX;
+    }
   }
 }
 
@@ -47,14 +71,6 @@ void EpdFont::getTextDimensions(const char* string, int* w, int* h) const {
   *h = maxY - minY;
 }
 
-bool EpdFont::hasPrintableChars(const char* string) const {
-  int w = 0, h = 0;
-
-  getTextDimensions(string, &w, &h);
-
-  return w > 0 || h > 0;
-}
-
 const EpdGlyph* EpdFont::getGlyph(const uint32_t cp) const {
   const EpdUnicodeInterval* intervals = data->intervals;
   const int count = data->intervalCount;

lib/EpdFont/EpdFont.h

@@ -9,7 +9,6 @@ class EpdFont {
   explicit EpdFont(const EpdFontData* data) : data(data) {}
   ~EpdFont() = default;
   void getTextDimensions(const char* string, int* w, int* h) const;
-  bool hasPrintableChars(const char* string) const;
 
   const EpdGlyph* getGlyph(uint32_t cp) const;
 };

lib/EpdFont/EpdFontData.h

@@ -12,9 +12,18 @@ typedef struct {
   int16_t left;         ///< X dist from cursor pos to UL corner
   int16_t top;          ///< Y dist from cursor pos to UL corner
   uint16_t dataLength;  ///< Size of the font data.
-  uint32_t dataOffset;  ///< Pointer into EpdFont->bitmap
+  uint32_t dataOffset;  ///< Pointer into EpdFont->bitmap (or within-group offset for compressed fonts)
 } EpdGlyph;
 
+/// Compressed font group: a DEFLATE-compressed block of glyph bitmaps
+typedef struct {
+  uint32_t compressedOffset;  ///< Byte offset into compressed data array
+  uint32_t compressedSize;    ///< Compressed DEFLATE stream size
+  uint32_t uncompressedSize;  ///< Decompressed size
+  uint16_t glyphCount;        ///< Number of glyphs in this group
+  uint16_t firstGlyphIndex;   ///< First glyph index in the global glyph array
+} EpdFontGroup;
+
 /// Glyph interval structure
 typedef struct {
   uint32_t first;   ///< The first unicode code point of the interval
@@ -32,4 +41,6 @@ typedef struct {
   int ascender;                         ///< Maximal height of a glyph above the base line
   int descender;                        ///< Maximal height of a glyph below the base line
   bool is2Bit;
+  const EpdFontGroup* groups;  ///< NULL for uncompressed fonts
+  uint16_t groupCount;         ///< 0 for uncompressed fonts
 } EpdFontData;

lib/EpdFont/EpdFontFamily.cpp

@@ -22,10 +22,6 @@ void EpdFontFamily::getTextDimensions(const char* string, int* w, int* h, const
   getFont(style)->getTextDimensions(string, w, h);
 }
 
-bool EpdFontFamily::hasPrintableChars(const char* string, const Style style) const {
-  return getFont(style)->hasPrintableChars(string);
-}
-
 const EpdFontData* EpdFontFamily::getData(const Style style) const { return getFont(style)->data; }
 
 const EpdGlyph* EpdFontFamily::getGlyph(const uint32_t cp, const Style style) const {

lib/EpdFont/EpdFontFamily.h

@@ -10,7 +10,6 @@ class EpdFontFamily {
       : regular(regular), bold(bold), italic(italic), boldItalic(boldItalic) {}
   ~EpdFontFamily() = default;
   void getTextDimensions(const char* string, int* w, int* h, Style style = REGULAR) const;
-  bool hasPrintableChars(const char* string, Style style = REGULAR) const;
   const EpdFontData* getData(Style style = REGULAR) const;
   const EpdGlyph* getGlyph(uint32_t cp, Style style = REGULAR) const;
 

lib/EpdFont/FontDecompressor.cpp

@@ -0,0 +1,147 @@
+#include "FontDecompressor.h"
+
+#include <Logging.h>
+#include <uzlib.h>
+
+#include <cstdlib>
+#include <cstring>
+
+bool FontDecompressor::init() {
+  clearCache();
+  memset(&decomp, 0, sizeof(decomp));
+  return true;
+}
+
+void FontDecompressor::freeAllEntries() {
+  for (auto& entry : cache) {
+    if (entry.data) {
+      free(entry.data);
+      entry.data = nullptr;
+    }
+    entry.valid = false;
+  }
+}
+
+void FontDecompressor::deinit() { freeAllEntries(); }
+
+void FontDecompressor::clearCache() {
+  freeAllEntries();
+  accessCounter = 0;
+}
+
+uint16_t FontDecompressor::getGroupIndex(const EpdFontData* fontData, uint16_t glyphIndex) {
+  for (uint16_t i = 0; i < fontData->groupCount; i++) {
+    uint16_t first = fontData->groups[i].firstGlyphIndex;
+    if (glyphIndex >= first && glyphIndex < first + fontData->groups[i].glyphCount) {
+      return i;
+    }
+  }
+  return fontData->groupCount;  // sentinel = not found
+}
+
+FontDecompressor::CacheEntry* FontDecompressor::findInCache(const EpdFontData* fontData, uint16_t groupIndex) {
+  for (auto& entry : cache) {
+    if (entry.valid && entry.font == fontData && entry.groupIndex == groupIndex) {
+      return &entry;
+    }
+  }
+  return nullptr;
+}
+
+FontDecompressor::CacheEntry* FontDecompressor::findEvictionCandidate() {
+  // Find an invalid slot first
+  for (auto& entry : cache) {
+    if (!entry.valid) {
+      return &entry;
+    }
+  }
+  // Otherwise evict LRU
+  CacheEntry* lru = &cache[0];
+  for (auto& entry : cache) {
+    if (entry.lastUsed < lru->lastUsed) {
+      lru = &entry;
+    }
+  }
+  return lru;
+}
+
+bool FontDecompressor::decompressGroup(const EpdFontData* fontData, uint16_t groupIndex, CacheEntry* entry) {
+  const EpdFontGroup& group = fontData->groups[groupIndex];
+
+  // Free old buffer if reusing a slot
+  if (entry->data) {
+    free(entry->data);
+    entry->data = nullptr;
+  }
+  entry->valid = false;
+
+  // Allocate output buffer
+  auto* outBuf = static_cast<uint8_t*>(malloc(group.uncompressedSize));
+  if (!outBuf) {
+    LOG_ERR("FDC", "Failed to allocate %u bytes for group %u", group.uncompressedSize, groupIndex);
+    return false;
+  }
+
+  // Decompress using uzlib
+  const uint8_t* inputBuf = &fontData->bitmap[group.compressedOffset];
+
+  uzlib_uncompress_init(&decomp, NULL, 0);
+  decomp.source = inputBuf;
+  decomp.source_limit = inputBuf + group.compressedSize;
+  decomp.dest_start = outBuf;
+  decomp.dest = outBuf;
+  decomp.dest_limit = outBuf + group.uncompressedSize;
+
+  int res = uzlib_uncompress(&decomp);
+
+  if (res < 0 || decomp.dest != decomp.dest_limit) {
+    LOG_ERR("FDC", "Decompression failed for group %u (status %d)", groupIndex, res);
+    free(outBuf);
+    return false;
+  }
+
+  entry->font = fontData;
+  entry->groupIndex = groupIndex;
+  entry->data = outBuf;
+  entry->dataSize = group.uncompressedSize;
+  entry->valid = true;
+  return true;
+}
+
+const uint8_t* FontDecompressor::getBitmap(const EpdFontData* fontData, const EpdGlyph* glyph, uint16_t glyphIndex) {
+  if (!fontData->groups || fontData->groupCount == 0) {
+    return &fontData->bitmap[glyph->dataOffset];
+  }
+
+  uint16_t groupIndex = getGroupIndex(fontData, glyphIndex);
+  if (groupIndex >= fontData->groupCount) {
+    LOG_ERR("FDC", "Glyph %u not found in any group", glyphIndex);
+    return nullptr;
+  }
+
+  // Check cache
+  CacheEntry* entry = findInCache(fontData, groupIndex);
+  if (entry) {
+    entry->lastUsed = ++accessCounter;
+    if (glyph->dataOffset + glyph->dataLength > entry->dataSize) {
+      LOG_ERR("FDC", "dataOffset %u + dataLength %u out of bounds for group %u (size %u)", glyph->dataOffset,
+              glyph->dataLength, groupIndex, entry->dataSize);
+      return nullptr;
+    }
+    return &entry->data[glyph->dataOffset];
+  }
+
+  // Cache miss - decompress
+  entry = findEvictionCandidate();
+  if (!decompressGroup(fontData, groupIndex, entry)) {
+    return nullptr;
+  }
+
+  entry->lastUsed = ++accessCounter;
+  if (glyph->dataOffset + glyph->dataLength > entry->dataSize) {
+    LOG_ERR("FDC", "dataOffset %u + dataLength %u out of bounds for group %u (size %u)", glyph->dataOffset,
+            glyph->dataLength, groupIndex, entry->dataSize);
+    return nullptr;
+  }
+  return &entry->data[glyph->dataOffset];
+}

lib/EpdFont/FontDecompressor.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <uzlib.h>
+
+#include <cstdint>
+
+#include "EpdFontData.h"
+
+class FontDecompressor {
+ public:
+  bool init();
+  void deinit();
+
+  // Returns pointer to decompressed bitmap data for the given glyph.
+  // Valid until LRU eviction (safe for the duration of one glyph render).
+  const uint8_t* getBitmap(const EpdFontData* fontData, const EpdGlyph* glyph, uint16_t glyphIndex);
+
+  // Evict all cached decompressed groups (call between pages for within-page-only caching).
+  void clearCache();
+
+ private:
+  static constexpr uint8_t CACHE_SLOTS = 4;
+
+  struct CacheEntry {
+    const EpdFontData* font = nullptr;
+    uint16_t groupIndex = 0;
+    uint8_t* data = nullptr;
+    uint32_t dataSize = 0;
+    uint32_t lastUsed = 0;
+    bool valid = false;
+  };
+
+  struct uzlib_uncomp decomp = {};
+  CacheEntry cache[CACHE_SLOTS] = {};
+  uint32_t accessCounter = 0;
+
+  void freeAllEntries();
+  uint16_t getGroupIndex(const EpdFontData* fontData, uint16_t glyphIndex);
+  CacheEntry* findInCache(const EpdFontData* fontData, uint16_t groupIndex);
+  CacheEntry* findEvictionCandidate();
+  bool decompressGroup(const EpdFontData* fontData, uint16_t groupIndex, CacheEntry* entry);
+};

lib/EpdFont/builtinFonts/notosans_8_regular.h

@@ -1619,4 +1619,6 @@ static const EpdFontData notosans_8_regular = {
     18,
     -5,
     false,
+    nullptr,
+    0,
 };

lib/EpdFont/builtinFonts/ubuntu_10_bold.h

@@ -1522,4 +1522,6 @@ static const EpdFontData ubuntu_10_bold = {
     20,
     -4,
     false,
+    nullptr,
+    0,
 };

lib/EpdFont/builtinFonts/ubuntu_10_regular.h

@@ -1436,4 +1436,6 @@ static const EpdFontData ubuntu_10_regular = {
     20,
     -4,
     false,
+    nullptr,
+    0,
 };

lib/EpdFont/builtinFonts/ubuntu_12_bold.h

@@ -1832,4 +1832,6 @@ static const EpdFontData ubuntu_12_bold = {
     24,
     -5,
     false,
+    nullptr,
+    0,
 };

lib/EpdFont/builtinFonts/ubuntu_12_regular.h

@@ -1724,4 +1724,6 @@ static const EpdFontData ubuntu_12_regular = {
     24,
     -5,
     false,
+    nullptr,
+    0,
 };

lib/EpdFont/scripts/convert-builtin-fonts.sh

@@ -14,7 +14,7 @@ for size in ${BOOKERLY_FONT_SIZES[@]}; do
     font_name="bookerly_${size}_$(echo $style | tr '[:upper:]' '[:lower:]')"
     font_path="../builtinFonts/source/Bookerly/Bookerly-${style}.ttf"
     output_path="../builtinFonts/${font_name}.h"
-    python fontconvert.py $font_name $size $font_path --2bit > $output_path
+    python fontconvert.py $font_name $size $font_path --2bit --compress > $output_path
     echo "Generated $output_path"
   done
 done
@@ -24,7 +24,7 @@ for size in ${NOTOSANS_FONT_SIZES[@]}; do
     font_name="notosans_${size}_$(echo $style | tr '[:upper:]' '[:lower:]')"
     font_path="../builtinFonts/source/NotoSans/NotoSans-${style}.ttf"
     output_path="../builtinFonts/${font_name}.h"
-    python fontconvert.py $font_name $size $font_path --2bit > $output_path
+    python fontconvert.py $font_name $size $font_path --2bit --compress > $output_path
     echo "Generated $output_path"
   done
 done
@@ -34,7 +34,7 @@ for size in ${OPENDYSLEXIC_FONT_SIZES[@]}; do
     font_name="opendyslexic_${size}_$(echo $style | tr '[:upper:]' '[:lower:]')"
     font_path="../builtinFonts/source/OpenDyslexic/OpenDyslexic-${style}.otf"
     output_path="../builtinFonts/${font_name}.h"
-    python fontconvert.py $font_name $size $font_path --2bit > $output_path
+    python fontconvert.py $font_name $size $font_path --2bit --compress > $output_path
     echo "Generated $output_path"
   done
 done
@@ -53,3 +53,7 @@ for size in ${UI_FONT_SIZES[@]}; do
 done
 
 python fontconvert.py notosans_8_regular 8 ../builtinFonts/source/NotoSans/NotoSans-Regular.ttf > ../builtinFonts/notosans_8_regular.h
+
+echo ""
+echo "Running compression verification..."
+python verify_compression.py ../builtinFonts/

lib/EpdFont/scripts/fontconvert.py

@@ -15,6 +15,7 @@ parser.add_argument("size", type=int, help="font size to use.")
 parser.add_argument("fontstack", action="store", nargs='+', help="list of font files, ordered by descending priority.")
 parser.add_argument("--2bit", dest="is2Bit", action="store_true", help="generate 2-bit greyscale bitmap instead of 1-bit black and white.")
 parser.add_argument("--additional-intervals", dest="additional_intervals", action="append", help="Additional code point intervals to export as min,max. This argument can be repeated.")
+parser.add_argument("--compress", dest="compress", action="store_true", help="Compress glyph bitmaps using DEFLATE with group-based compression.")
 args = parser.parse_args()
 
 GlyphProps = namedtuple("GlyphProps", ["width", "height", "advance_x", "left", "top", "data_length", "data_offset", "code_point"])
@@ -270,21 +271,115 @@ for index, glyph in enumerate(all_glyphs):
     glyph_data.extend([b for b in packed])
     glyph_props.append(props)
 
+compress = args.compress
+
+# Build groups for compression
+if compress:
+    # Script-based grouping: glyphs that co-occur in typical text rendering
+    # are grouped together for efficient LRU caching on the embedded target.
+    # Since glyphs are in codepoint order, glyphs in the same Unicode block
+    # are contiguous in the array and form natural groups.
+    SCRIPT_GROUP_RANGES = [
+        (0x0000, 0x007F),   # ASCII
+        (0x0080, 0x00FF),   # Latin-1 Supplement
+        (0x0100, 0x017F),   # Latin Extended-A
+        (0x0300, 0x036F),   # Combining Diacritical Marks
+        (0x0400, 0x04FF),   # Cyrillic
+        (0x2000, 0x206F),   # General Punctuation
+        (0x2070, 0x209F),   # Superscripts & Subscripts
+        (0x20A0, 0x20CF),   # Currency Symbols
+        (0x2190, 0x21FF),   # Arrows
+        (0x2200, 0x22FF),   # Math Operators
+        (0xFFFD, 0xFFFD),   # Replacement Character
+    ]
+
+    def get_script_group(code_point):
+        for i, (start, end) in enumerate(SCRIPT_GROUP_RANGES):
+            if start <= code_point <= end:
+                return i
+        return -1
+
+    groups = []  # list of (first_glyph_index, glyph_count)
+    current_group_id = None
+    group_start = 0
+    group_count = 0
+
+    for i, (props, packed) in enumerate(all_glyphs):
+        sg = get_script_group(props.code_point)
+        if sg != current_group_id:
+            if group_count > 0:
+                groups.append((group_start, group_count))
+            current_group_id = sg
+            group_start = i
+            group_count = 1
+        else:
+            group_count += 1
+
+    if group_count > 0:
+        groups.append((group_start, group_count))
+
+    # Compress each group
+    compressed_groups = []  # list of (compressed_bytes, uncompressed_size, glyph_count, first_glyph_index)
+    compressed_bitmap_data = []
+    compressed_offset = 0
+
+    # Also build modified glyph props with within-group offsets
+    modified_glyph_props = list(glyph_props)
+
+    for first_idx, count in groups:
+        # Concatenate bitmap data for this group
+        group_data = b''
+        for gi in range(first_idx, first_idx + count):
+            props, packed = all_glyphs[gi]
+            # Update glyph's dataOffset to be within-group offset
+            within_group_offset = len(group_data)
+            old_props = modified_glyph_props[gi]
+            modified_glyph_props[gi] = GlyphProps(
+                width=old_props.width,
+                height=old_props.height,
+                advance_x=old_props.advance_x,
+                left=old_props.left,
+                top=old_props.top,
+                data_length=old_props.data_length,
+                data_offset=within_group_offset,
+                code_point=old_props.code_point,
+            )
+            group_data += packed
+
+        # Compress with raw DEFLATE (no zlib/gzip header)
+        compressor = zlib.compressobj(level=9, wbits=-15)
+        compressed = compressor.compress(group_data) + compressor.flush()
+
+        compressed_groups.append((compressed, len(group_data), count, first_idx))
+        compressed_bitmap_data.extend(compressed)
+        compressed_offset += len(compressed)
+
+    glyph_props = modified_glyph_props
+    total_compressed = len(compressed_bitmap_data)
+    total_uncompressed = len(glyph_data)
+    print(f"// Compression: {total_uncompressed} -> {total_compressed} bytes ({100*total_compressed/total_uncompressed:.1f}%), {len(groups)} groups", file=sys.stderr)
+
 print(f"""/**
  * generated by fontconvert.py
  * name: {font_name}
  * size: {size}
- * mode: {'2-bit' if is2Bit else '1-bit'}
+ * mode: {'2-bit' if is2Bit else '1-bit'}{'  compressed: true' if compress else ''}
  * Command used: {' '.join(sys.argv)}
  */
 #pragma once
 #include "EpdFontData.h"
 """)
 
-print(f"static const uint8_t {font_name}Bitmaps[{len(glyph_data)}] = {{")
-for c in chunks(glyph_data, 16):
-    print ("    " + " ".join(f"0x{b:02X}," for b in c))
-print ("};\n");
+if compress:
+    print(f"static const uint8_t {font_name}Bitmaps[{len(compressed_bitmap_data)}] = {{")
+    for c in chunks(compressed_bitmap_data, 16):
+        print ("    " + " ".join(f"0x{b:02X}," for b in c))
+    print ("};\n");
+else:
+    print(f"static const uint8_t {font_name}Bitmaps[{len(glyph_data)}] = {{")
+    for c in chunks(glyph_data, 16):
+        print ("    " + " ".join(f"0x{b:02X}," for b in c))
+    print ("};\n");
 
 print(f"static const EpdGlyph {font_name}Glyphs[] = {{")
 for i, g in enumerate(glyph_props):
@@ -298,6 +393,14 @@ for i_start, i_end in intervals:
     offset += i_end - i_start + 1
 print ("};\n");
 
+if compress:
+    print(f"static const EpdFontGroup {font_name}Groups[] = {{")
+    compressed_offset = 0
+    for compressed, uncompressed_size, count, first_idx in compressed_groups:
+        print(f"    {{ {compressed_offset}, {len(compressed)}, {uncompressed_size}, {count}, {first_idx} }},")
+        compressed_offset += len(compressed)
+    print("};\n")
+
 print(f"static const EpdFontData {font_name} = {{")
 print(f"    {font_name}Bitmaps,")
 print(f"    {font_name}Glyphs,")
@@ -307,4 +410,10 @@ print(f"    {norm_ceil(face.size.height)},")
 print(f"    {norm_ceil(face.size.ascender)},")
 print(f"    {norm_floor(face.size.descender)},")
 print(f"    {'true' if is2Bit else 'false'},")
+if compress:
+    print(f"    {font_name}Groups,")
+    print(f"    {len(compressed_groups)},")
+else:
+    print(f"    nullptr,")
+    print(f"    0,")
 print("};")

lib/EpdFont/scripts/verify_compression.py

@@ -0,0 +1,164 @@
+#!/usr/bin/env python3
+"""
+Round-trip verification for compressed font headers.
+
+Parses each generated .h file in the given directory, identifies compressed fonts
+(those with a Groups array), decompresses each group, and verifies that
+decompression succeeds and all glyph offsets/lengths fall within bounds.
+"""
+import os
+import re
+import sys
+import zlib
+
+
+def parse_hex_array(text):
+    """Extract bytes from a C hex array string like '{ 0xAB, 0xCD, ... }'"""
+    hex_vals = re.findall(r'0x([0-9A-Fa-f]{2})', text)
+    return bytes(int(h, 16) for h in hex_vals)
+
+
+def parse_groups(text):
+    """Parse EpdFontGroup array entries: { compressedOffset, compressedSize, uncompressedSize, glyphCount, firstGlyphIndex }"""
+    groups = []
+    for match in re.finditer(r'\{\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\}', text):
+        groups.append({
+            'compressedOffset': int(match.group(1)),
+            'compressedSize': int(match.group(2)),
+            'uncompressedSize': int(match.group(3)),
+            'glyphCount': int(match.group(4)),
+            'firstGlyphIndex': int(match.group(5)),
+        })
+    return groups
+
+
+def parse_glyphs(text):
+    """Parse EpdGlyph array entries: { width, height, advanceX, left, top, dataLength, dataOffset }"""
+    glyphs = []
+    for match in re.finditer(r'\{\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*\}', text):
+        glyphs.append({
+            'width': int(match.group(1)),
+            'height': int(match.group(2)),
+            'advanceX': int(match.group(3)),
+            'left': int(match.group(4)),
+            'top': int(match.group(5)),
+            'dataLength': int(match.group(6)),
+            'dataOffset': int(match.group(7)),
+        })
+    return glyphs
+
+
+def verify_font_file(filepath):
+    """Verify a single font header file. Returns (font_name, success, message)."""
+    with open(filepath, 'r') as f:
+        content = f.read()
+
+    # Check if this is a compressed font (has Groups array)
+    groups_match = re.search(r'static const EpdFontGroup (\w+)Groups\[\]', content)
+    if not groups_match:
+        return (os.path.basename(filepath), None, "uncompressed, skipping")
+
+    font_name = groups_match.group(1)
+
+    # Extract bitmap data
+    bitmap_match = re.search(
+        r'static const uint8_t ' + re.escape(font_name) + r'Bitmaps\[\d+\]\s*=\s*\{([^}]+)\}',
+        content, re.DOTALL
+    )
+    if not bitmap_match:
+        return (font_name, False, "could not find Bitmaps array")
+
+    compressed_data = parse_hex_array(bitmap_match.group(1))
+
+    # Extract groups
+    groups_array_match = re.search(
+        r'static const EpdFontGroup ' + re.escape(font_name) + r'Groups\[\]\s*=\s*\{(.+?)\};',
+        content, re.DOTALL
+    )
+    if not groups_array_match:
+        return (font_name, False, "could not find Groups array")
+
+    groups = parse_groups(groups_array_match.group(1))
+    if not groups:
+        return (font_name, False, "Groups array parsed to 0 entries; check format")
+
+    # Extract glyphs
+    glyphs_match = re.search(
+        r'static const EpdGlyph ' + re.escape(font_name) + r'Glyphs\[\]\s*=\s*\{(.+?)\};',
+        content, re.DOTALL
+    )
+    if not glyphs_match:
+        return (font_name, False, "could not find Glyphs array")
+
+    glyphs = parse_glyphs(glyphs_match.group(1))
+
+    # Verify each group
+    for gi, group in enumerate(groups):
+        # Extract compressed chunk
+        chunk = compressed_data[group['compressedOffset']:group['compressedOffset'] + group['compressedSize']]
+        if len(chunk) != group['compressedSize']:
+            return (font_name, False, f"group {gi}: compressed data truncated (expected {group['compressedSize']}, got {len(chunk)})")
+
+        # Decompress with raw DEFLATE
+        try:
+            decompressed = zlib.decompress(chunk, -15)
+        except zlib.error as e:
+            return (font_name, False, f"group {gi}: decompression failed: {e}")
+
+        if len(decompressed) != group['uncompressedSize']:
+            return (font_name, False, f"group {gi}: size mismatch (expected {group['uncompressedSize']}, got {len(decompressed)})")
+
+        # Verify each glyph's data within the group
+        first = group['firstGlyphIndex']
+        for j in range(group['glyphCount']):
+            glyph_idx = first + j
+            if glyph_idx >= len(glyphs):
+                return (font_name, False, f"group {gi}: glyph index {glyph_idx} out of range")
+
+            glyph = glyphs[glyph_idx]
+            offset = glyph['dataOffset']
+            length = glyph['dataLength']
+
+            if offset + length > len(decompressed):
+                return (font_name, False, f"group {gi}, glyph {glyph_idx}: data extends beyond decompressed buffer "
+                        f"(offset={offset}, length={length}, decompressed_size={len(decompressed)})")
+
+    return (font_name, True, f"{len(groups)} groups, {len(glyphs)} glyphs OK")
+
+
+def main():
+    if len(sys.argv) < 2:
+        print(f"Usage: {sys.argv[0]} <font_headers_directory>", file=sys.stderr)
+        sys.exit(1)
+
+    font_dir = sys.argv[1]
+    if not os.path.isdir(font_dir):
+        print(f"Error: {font_dir} is not a directory", file=sys.stderr)
+        sys.exit(1)
+
+    files = sorted(f for f in os.listdir(font_dir) if f.endswith('.h') and f != 'all.h')
+    passed = 0
+    failed = 0
+    skipped = 0
+
+    for filename in files:
+        filepath = os.path.join(font_dir, filename)
+        _font_name, success, message = verify_font_file(filepath)
+
+        if success is None:
+            skipped += 1
+        elif success:
+            passed += 1
+            print(f"  PASS: {filename} ({message})")
+        else:
+            failed += 1
+            print(f"  FAIL: {filename} - {message}")
+
+    print(f"\nResults: {passed} passed, {failed} failed, {skipped} skipped (uncompressed)")
+
+    if failed > 0:
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()

lib/Epub/Epub.cpp

@@ -4,6 +4,7 @@
 #include <HalStorage.h>
 #include <JpegToBmpConverter.h>
 #include <Logging.h>
+#include <PngToBmpConverter.h>
 #include <ZipFile.h>
 
 #include "Epub/parsers/ContainerParser.h"
@@ -76,6 +77,54 @@ bool Epub::parseContentOpf(BookMetadataCache::BookMetadata& bookMetadata) {
   bookMetadata.author = opfParser.author;
   bookMetadata.language = opfParser.language;
   bookMetadata.coverItemHref = opfParser.coverItemHref;
+
+  // Guide-based cover fallback: if no cover found via metadata/properties,
+  // try extracting the image reference from the guide's cover page XHTML
+  if (bookMetadata.coverItemHref.empty() && !opfParser.guideCoverPageHref.empty()) {
+    LOG_DBG("EBP", "No cover from metadata, trying guide cover page: %s", opfParser.guideCoverPageHref.c_str());
+    size_t coverPageSize;
+    uint8_t* coverPageData = readItemContentsToBytes(opfParser.guideCoverPageHref, &coverPageSize, true);
+    if (coverPageData) {
+      const std::string coverPageHtml(reinterpret_cast<char*>(coverPageData), coverPageSize);
+      free(coverPageData);
+
+      // Determine base path of the cover page for resolving relative image references
+      std::string coverPageBase;
+      const auto lastSlash = opfParser.guideCoverPageHref.rfind('/');
+      if (lastSlash != std::string::npos) {
+        coverPageBase = opfParser.guideCoverPageHref.substr(0, lastSlash + 1);
+      }
+
+      // Search for image references: xlink:href="..." (SVG) and src="..." (img)
+      std::string imageRef;
+      for (const char* pattern : {"xlink:href=\"", "src=\""}) {
+        auto pos = coverPageHtml.find(pattern);
+        while (pos != std::string::npos) {
+          pos += strlen(pattern);
+          const auto endPos = coverPageHtml.find('"', pos);
+          if (endPos != std::string::npos) {
+            const auto ref = coverPageHtml.substr(pos, endPos - pos);
+            // Check if it's an image file
+            if (ref.length() >= 4) {
+              const auto ext = ref.substr(ref.length() - 4);
+              if (ext == ".png" || ext == ".jpg" || ext == "jpeg" || ext == ".gif") {
+                imageRef = ref;
+                break;
+              }
+            }
+          }
+          pos = coverPageHtml.find(pattern, pos);
+        }
+        if (!imageRef.empty()) break;
+      }
+
+      if (!imageRef.empty()) {
+        bookMetadata.coverItemHref = FsHelpers::normalisePath(coverPageBase + imageRef);
+        LOG_DBG("EBP", "Found cover image from guide: %s", bookMetadata.coverItemHref.c_str());
+      }
+    }
+  }
+
   bookMetadata.textReferenceHref = opfParser.textReferenceHref;
 
   if (!opfParser.tocNcxPath.empty()) {
@@ -208,68 +257,80 @@ bool Epub::parseTocNavFile() const {
   return true;
 }
 
-std::string Epub::getCssRulesCache() const { return cachePath + "/css_rules.cache"; }
-
-bool Epub::loadCssRulesFromCache() const {
-  FsFile cssCacheFile;
-  if (Storage.openFileForRead("EBP", getCssRulesCache(), cssCacheFile)) {
-    if (cssParser->loadFromCache(cssCacheFile)) {
-      cssCacheFile.close();
-      LOG_DBG("EBP", "Loaded CSS rules from cache");
-      return true;
-    }
-    cssCacheFile.close();
-    LOG_DBG("EBP", "CSS cache invalid, reparsing");
-  }
-  return false;
-}
-
 void Epub::parseCssFiles() const {
+  // Maximum CSS file size we'll attempt to parse (uncompressed)
+  // Larger files risk memory exhaustion on ESP32
+  constexpr size_t MAX_CSS_FILE_SIZE = 128 * 1024;  // 128KB
+  // Minimum heap required before attempting CSS parsing
+  constexpr size_t MIN_HEAP_FOR_CSS_PARSING = 64 * 1024;  // 64KB
+
   if (cssFiles.empty()) {
     LOG_DBG("EBP", "No CSS files to parse, but CssParser created for inline styles");
   }
 
-  // Try to load from CSS cache first
-  if (!loadCssRulesFromCache()) {
-    // Cache miss - parse CSS files
-    for (const auto& cssPath : cssFiles) {
-      LOG_DBG("EBP", "Parsing CSS file: %s", cssPath.c_str());
+  LOG_DBG("EBP", "CSS files to parse: %zu", cssFiles.size());
 
-      // Extract CSS file to temp location
-      const auto tmpCssPath = getCachePath() + "/.tmp.css";
-      FsFile tempCssFile;
-      if (!Storage.openFileForWrite("EBP", tmpCssPath, tempCssFile)) {
-        LOG_ERR("EBP", "Could not create temp CSS file");
-        continue;
-      }
-      if (!readItemContentsToStream(cssPath, tempCssFile, 1024)) {
-        LOG_ERR("EBP", "Could not read CSS file: %s", cssPath.c_str());
-        tempCssFile.close();
-        Storage.remove(tmpCssPath.c_str());
-        continue;
-      }
-      tempCssFile.close();
+  // See if we have a cached version of the CSS rules
+  if (cssParser->hasCache()) {
+    LOG_DBG("EBP", "CSS cache exists, skipping parseCssFiles");
+    return;
+  }
 
-      // Parse the CSS file
-      if (!Storage.openFileForRead("EBP", tmpCssPath, tempCssFile)) {
-        LOG_ERR("EBP", "Could not open temp CSS file for reading");
-        Storage.remove(tmpCssPath.c_str());
+  // No cache yet - parse CSS files
+  for (const auto& cssPath : cssFiles) {
+    LOG_DBG("EBP", "Parsing CSS file: %s", cssPath.c_str());
+
+    // Check heap before parsing - CSS parsing allocates heavily
+    const uint32_t freeHeap = ESP.getFreeHeap();
+    if (freeHeap < MIN_HEAP_FOR_CSS_PARSING) {
+      LOG_ERR("EBP", "Insufficient heap for CSS parsing (%u bytes free, need %zu), skipping: %s", freeHeap,
+              MIN_HEAP_FOR_CSS_PARSING, cssPath.c_str());
+      continue;
+    }
+
+    // Check CSS file size before decompressing - skip files that are too large
+    size_t cssFileSize = 0;
+    if (getItemSize(cssPath, &cssFileSize)) {
+      if (cssFileSize > MAX_CSS_FILE_SIZE) {
+        LOG_ERR("EBP", "CSS file too large (%zu bytes > %zu max), skipping: %s", cssFileSize, MAX_CSS_FILE_SIZE,
+                cssPath.c_str());
         continue;
       }
-      cssParser->loadFromStream(tempCssFile);
+    }
+
+    // Extract CSS file to temp location
+    const auto tmpCssPath = getCachePath() + "/.tmp.css";
+    FsFile tempCssFile;
+    if (!Storage.openFileForWrite("EBP", tmpCssPath, tempCssFile)) {
+      LOG_ERR("EBP", "Could not create temp CSS file");
+      continue;
+    }
+    if (!readItemContentsToStream(cssPath, tempCssFile, 1024)) {
+      LOG_ERR("EBP", "Could not read CSS file: %s", cssPath.c_str());
       tempCssFile.close();
       Storage.remove(tmpCssPath.c_str());
+      continue;
     }
+    tempCssFile.close();
 
-    // Save to cache for next time
-    FsFile cssCacheFile;
-    if (Storage.openFileForWrite("EBP", getCssRulesCache(), cssCacheFile)) {
-      cssParser->saveToCache(cssCacheFile);
-      cssCacheFile.close();
+    // Parse the CSS file
+    if (!Storage.openFileForRead("EBP", tmpCssPath, tempCssFile)) {
+      LOG_ERR("EBP", "Could not open temp CSS file for reading");
+      Storage.remove(tmpCssPath.c_str());
+      continue;
     }
-
-    LOG_DBG("EBP", "Loaded %zu CSS style rules from %zu files", cssParser->ruleCount(), cssFiles.size());
+    cssParser->loadFromStream(tempCssFile);
+    tempCssFile.close();
+    Storage.remove(tmpCssPath.c_str());
   }
+
+  // Save to cache for next time
+  if (!cssParser->saveToCache()) {
+    LOG_ERR("EBP", "Failed to save CSS rules to cache");
+  }
+  cssParser->clear();
+
+  LOG_DBG("EBP", "Loaded %zu CSS style rules from %zu files", cssParser->ruleCount(), cssFiles.size());
 }
 
 // load in the meta data for the epub file
@@ -279,18 +340,24 @@ bool Epub::load(const bool buildIfMissing, const bool skipLoadingCss) {
   // Initialize spine/TOC cache
   bookMetadataCache.reset(new BookMetadataCache(cachePath));
   // Always create CssParser - needed for inline style parsing even without CSS files
-  cssParser.reset(new CssParser());
+  cssParser.reset(new CssParser(cachePath));
 
   // Try to load existing cache first
   if (bookMetadataCache->load()) {
-    if (!skipLoadingCss && !loadCssRulesFromCache()) {
-      LOG_DBG("EBP", "Warning: CSS rules cache not found, attempting to parse CSS files");
-      // to get CSS file list
-      if (!parseContentOpf(bookMetadataCache->coreMetadata)) {
-        LOG_ERR("EBP", "Could not parse content.opf from cached bookMetadata for CSS files");
-        // continue anyway - book will work without CSS and we'll still load any inline style CSS
+    if (!skipLoadingCss) {
+      // Rebuild CSS cache when missing or when cache version changed (loadFromCache removes stale file)
+      if (!cssParser->hasCache() || !cssParser->loadFromCache()) {
+        LOG_DBG("EBP", "CSS rules cache missing or stale, attempting to parse CSS files");
+        cssParser->deleteCache();
+
+        if (!parseContentOpf(bookMetadataCache->coreMetadata)) {
+          LOG_ERR("EBP", "Could not parse content.opf from cached bookMetadata for CSS files");
+          // continue anyway - book will work without CSS and we'll still load any inline style CSS
+        }
+        parseCssFiles();
+        // Invalidate section caches so they are rebuilt with the new CSS
+        Storage.removeDir((cachePath + "/sections").c_str());
       }
-      parseCssFiles();
     }
     LOG_DBG("EBP", "Loaded ePub: %s", filepath.c_str());
     return true;
@@ -391,6 +458,7 @@ bool Epub::load(const bool buildIfMissing, const bool skipLoadingCss) {
   if (!skipLoadingCss) {
     // Parse CSS files after cache reload
     parseCssFiles();
+    Storage.removeDir((cachePath + "/sections").c_str());
   }
 
   LOG_DBG("EBP", "Loaded ePub: %s", filepath.c_str());
@@ -503,12 +571,44 @@ bool Epub::generateCoverBmp(bool cropped) const {
       LOG_ERR("EBP", "Failed to generate BMP from cover image");
       Storage.remove(getCoverBmpPath(cropped).c_str());
     }
-    LOG_DBG("EBP", "Generated BMP from cover image, success: %s", success ? "yes" : "no");
+    LOG_DBG("EBP", "Generated BMP from JPG cover image, success: %s", success ? "yes" : "no");
     return success;
-  } else {
-    LOG_ERR("EBP", "Cover image is not a supported format, skipping");
   }
 
+  if (coverImageHref.substr(coverImageHref.length() - 4) == ".png") {
+    LOG_DBG("EBP", "Generating BMP from PNG cover image (%s mode)", cropped ? "cropped" : "fit");
+    const auto coverPngTempPath = getCachePath() + "/.cover.png";
+
+    FsFile coverPng;
+    if (!Storage.openFileForWrite("EBP", coverPngTempPath, coverPng)) {
+      return false;
+    }
+    readItemContentsToStream(coverImageHref, coverPng, 1024);
+    coverPng.close();
+
+    if (!Storage.openFileForRead("EBP", coverPngTempPath, coverPng)) {
+      return false;
+    }
+
+    FsFile coverBmp;
+    if (!Storage.openFileForWrite("EBP", getCoverBmpPath(cropped), coverBmp)) {
+      coverPng.close();
+      return false;
+    }
+    const bool success = PngToBmpConverter::pngFileToBmpStream(coverPng, coverBmp, cropped);
+    coverPng.close();
+    coverBmp.close();
+    Storage.remove(coverPngTempPath.c_str());
+
+    if (!success) {
+      LOG_ERR("EBP", "Failed to generate BMP from PNG cover image");
+      Storage.remove(getCoverBmpPath(cropped).c_str());
+    }
+    LOG_DBG("EBP", "Generated BMP from PNG cover image, success: %s", success ? "yes" : "no");
+    return success;
+  }
+
+  LOG_ERR("EBP", "Cover image is not a supported format, skipping");
   return false;
 }
 
@@ -566,6 +666,40 @@ bool Epub::generateThumbBmp(int height) const {
     }
     LOG_DBG("EBP", "Generated thumb BMP from JPG cover image, success: %s", success ? "yes" : "no");
     return success;
+  } else if (coverImageHref.substr(coverImageHref.length() - 4) == ".png") {
+    LOG_DBG("EBP", "Generating thumb BMP from PNG cover image");
+    const auto coverPngTempPath = getCachePath() + "/.cover.png";
+
+    FsFile coverPng;
+    if (!Storage.openFileForWrite("EBP", coverPngTempPath, coverPng)) {
+      return false;
+    }
+    readItemContentsToStream(coverImageHref, coverPng, 1024);
+    coverPng.close();
+
+    if (!Storage.openFileForRead("EBP", coverPngTempPath, coverPng)) {
+      return false;
+    }
+
+    FsFile thumbBmp;
+    if (!Storage.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp)) {
+      coverPng.close();
+      return false;
+    }
+    int THUMB_TARGET_WIDTH = height * 0.6;
+    int THUMB_TARGET_HEIGHT = height;
+    const bool success =
+        PngToBmpConverter::pngFileTo1BitBmpStreamWithSize(coverPng, thumbBmp, THUMB_TARGET_WIDTH, THUMB_TARGET_HEIGHT);
+    coverPng.close();
+    thumbBmp.close();
+    Storage.remove(coverPngTempPath.c_str());
+
+    if (!success) {
+      LOG_ERR("EBP", "Failed to generate thumb BMP from PNG cover image");
+      Storage.remove(getThumbBmpPath(height).c_str());
+    }
+    LOG_DBG("EBP", "Generated thumb BMP from PNG cover image, success: %s", success ? "yes" : "no");
+    return success;
   } else {
     LOG_ERR("EBP", "Cover image is not a supported format, skipping thumbnail");
   }

lib/Epub/Epub.h

@@ -35,8 +35,6 @@ class Epub {
   bool parseTocNcxFile() const;
   bool parseTocNavFile() const;
   void parseCssFiles() const;
-  std::string getCssRulesCache() const;
-  bool loadCssRulesFromCache() const;
 
  public:
   explicit Epub(std::string filepath, const std::string& cacheDir) : filepath(std::move(filepath)) {
@@ -73,5 +71,5 @@ class Epub {
 
   size_t getBookSize() const;
   float calculateProgress(int currentSpineIndex, float currentSpineRead) const;
-  const CssParser* getCssParser() const { return cssParser.get(); }
+  CssParser* getCssParser() const { return cssParser.get(); }
 };

lib/Epub/Epub/Page.cpp

@@ -25,6 +25,29 @@ std::unique_ptr<PageLine> PageLine::deserialize(FsFile& file) {
   return std::unique_ptr<PageLine>(new PageLine(std::move(tb), xPos, yPos));
 }
 
+void PageImage::render(GfxRenderer& renderer, const int fontId, const int xOffset, const int yOffset) {
+  // Images don't use fontId or text rendering
+  imageBlock->render(renderer, xPos + xOffset, yPos + yOffset);
+}
+
+bool PageImage::serialize(FsFile& file) {
+  serialization::writePod(file, xPos);
+  serialization::writePod(file, yPos);
+
+  // serialize ImageBlock
+  return imageBlock->serialize(file);
+}
+
+std::unique_ptr<PageImage> PageImage::deserialize(FsFile& file) {
+  int16_t xPos;
+  int16_t yPos;
+  serialization::readPod(file, xPos);
+  serialization::readPod(file, yPos);
+
+  auto ib = ImageBlock::deserialize(file);
+  return std::unique_ptr<PageImage>(new PageImage(std::move(ib), xPos, yPos));
+}
+
 void Page::render(GfxRenderer& renderer, const int fontId, const int xOffset, const int yOffset) const {
   for (auto& element : elements) {
     element->render(renderer, fontId, xOffset, yOffset);
@@ -36,8 +59,9 @@ bool Page::serialize(FsFile& file) const {
   serialization::writePod(file, count);
 
   for (const auto& el : elements) {
-    // Only PageLine exists currently
-    serialization::writePod(file, static_cast<uint8_t>(TAG_PageLine));
+    // Use getTag() method to determine type
+    serialization::writePod(file, static_cast<uint8_t>(el->getTag()));
+
     if (!el->serialize(file)) {
       return false;
     }
@@ -59,6 +83,9 @@ std::unique_ptr<Page> Page::deserialize(FsFile& file) {
     if (tag == TAG_PageLine) {
       auto pl = PageLine::deserialize(file);
       page->elements.push_back(std::move(pl));
+    } else if (tag == TAG_PageImage) {
+      auto pi = PageImage::deserialize(file);
+      page->elements.push_back(std::move(pi));
     } else {
       LOG_ERR("PGE", "Deserialization failed: Unknown tag %u", tag);
       return nullptr;

lib/Epub/Epub/Page.h

@@ -1,13 +1,16 @@
 #pragma once
 #include <HalStorage.h>
 
+#include <algorithm>
 #include <utility>
 #include <vector>
 
+#include "blocks/ImageBlock.h"
 #include "blocks/TextBlock.h"
 
 enum PageElementTag : uint8_t {
   TAG_PageLine = 1,
+  TAG_PageImage = 2,  // New tag
 };
 
 // represents something that has been added to a page
@@ -19,6 +22,7 @@ class PageElement {
   virtual ~PageElement() = default;
   virtual void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) = 0;
   virtual bool serialize(FsFile& file) = 0;
+  virtual PageElementTag getTag() const = 0;  // Add type identification
 };
 
 // a line from a block element
@@ -30,9 +34,24 @@ class PageLine final : public PageElement {
       : PageElement(xPos, yPos), block(std::move(block)) {}
   void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) override;
   bool serialize(FsFile& file) override;
+  PageElementTag getTag() const override { return TAG_PageLine; }
   static std::unique_ptr<PageLine> deserialize(FsFile& file);
 };
 
+// New PageImage class
+class PageImage final : public PageElement {
+  std::shared_ptr<ImageBlock> imageBlock;
+
+ public:
+  PageImage(std::shared_ptr<ImageBlock> block, const int16_t xPos, const int16_t yPos)
+      : PageElement(xPos, yPos), imageBlock(std::move(block)) {}
+  void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) override;
+  bool serialize(FsFile& file) override;
+  PageElementTag getTag() const override { return TAG_PageImage; }
+  static std::unique_ptr<PageImage> deserialize(FsFile& file);
+  const ImageBlock& getImageBlock() const { return *imageBlock; }
+};
+
 class Page {
  public:
   // the list of block index and line numbers on this page
@@ -40,4 +59,38 @@ class Page {
   void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) const;
   bool serialize(FsFile& file) const;
   static std::unique_ptr<Page> deserialize(FsFile& file);
+
+  // Check if page contains any images (used to force full refresh)
+  bool hasImages() const {
+    return std::any_of(elements.begin(), elements.end(),
+                       [](const std::shared_ptr<PageElement>& el) { return el->getTag() == TAG_PageImage; });
+  }
+
+  // Get bounding box of all images on the page (union of image rects)
+  // Returns false if no images. Coordinates are relative to page origin.
+  bool getImageBoundingBox(int16_t& outX, int16_t& outY, int16_t& outW, int16_t& outH) const {
+    bool found = false;
+    int16_t minX = INT16_MAX, minY = INT16_MAX, maxX = INT16_MIN, maxY = INT16_MIN;
+    for (const auto& el : elements) {
+      if (el->getTag() == TAG_PageImage) {
+        const auto& img = static_cast<const PageImage&>(*el);
+        int16_t x = img.xPos;
+        int16_t y = img.yPos;
+        int16_t right = x + img.getImageBlock().getWidth();
+        int16_t bottom = y + img.getImageBlock().getHeight();
+        minX = std::min(minX, x);
+        minY = std::min(minY, y);
+        maxX = std::max(maxX, right);
+        maxY = std::max(maxY, bottom);
+        found = true;
+      }
+    }
+    if (found) {
+      outX = minX;
+      outY = minY;
+      outW = maxX - minX;
+      outH = maxY - minY;
+    }
+    return found;
+  }
 };

lib/Epub/Epub/ParsedText.cpp

@@ -29,15 +29,17 @@ void stripSoftHyphensInPlace(std::string& word) {
   }
 }
 
-// Returns the rendered width for a word while ignoring soft hyphen glyphs and optionally appending a visible hyphen.
+// Returns the advance width for a word while ignoring soft hyphen glyphs and optionally appending a visible hyphen.
+// Uses advance width (sum of glyph advances) rather than bounding box width so that italic glyph overhangs
+// don't inflate inter-word spacing.
 uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const std::string& word,
                           const EpdFontFamily::Style style, const bool appendHyphen = false) {
   if (word.size() == 1 && word[0] == ' ' && !appendHyphen) {
-    return renderer.getSpaceWidth(fontId);
+    return renderer.getSpaceWidth(fontId, style);
   }
   const bool hasSoftHyphen = containsSoftHyphen(word);
   if (!hasSoftHyphen && !appendHyphen) {
-    return renderer.getTextWidth(fontId, word.c_str(), style);
+    return renderer.getTextAdvanceX(fontId, word.c_str(), style);
   }
 
   std::string sanitized = word;
@@ -47,7 +49,7 @@ uint16_t measureWordWidth(const GfxRenderer& renderer, const int fontId, const s
   if (appendHyphen) {
     sanitized.push_back('-');
   }
-  return renderer.getTextWidth(fontId, sanitized.c_str(), style);
+  return renderer.getTextAdvanceX(fontId, sanitized.c_str(), style);
 }
 
 }  // namespace
@@ -376,20 +378,35 @@ bool ParsedText::hyphenateWordAtIndex(const size_t wordIndex, const int availabl
   words.insert(insertWordIt, remainder);
   wordStyles.insert(insertStyleIt, style);
 
-  // The remainder inherits whatever continuation status the original word had with the word after it.
-  // Find the continues entry for the original word and insert the remainder's entry after it.
+  // Continuation flag handling after splitting a word into prefix + remainder.
+  //
+  // The prefix keeps the original word's continuation flag so that no-break-space groups
+  // stay linked. The remainder always gets continues=false because it starts on the next
+  // line and is not attached to the prefix.
+  //
+  // Example: "200 Quadratkilometer" produces tokens:
+  //   [0] "200"               continues=false
+  //   [1] " "                 continues=true
+  //   [2] "Quadratkilometer"  continues=true   <-- the word being split
+  //
+  // After splitting "Quadratkilometer" at "Quadrat-" / "kilometer":
+  //   [0] "200"         continues=false
+  //   [1] " "           continues=true
+  //   [2] "Quadrat-"    continues=true   (KEPT — still attached to the no-break group)
+  //   [3] "kilometer"   continues=false  (NEW — starts fresh on the next line)
+  //
+  // This lets the backtracking loop keep the entire prefix group ("200 Quadrat-") on one
+  // line, while "kilometer" moves to the next line.
   auto continuesIt = wordContinues.begin();
   std::advance(continuesIt, wordIndex);
-  const bool originalContinuedToNext = *continuesIt;
-  // The original word (now prefix) does NOT continue to remainder (hyphen separates them)
-  *continuesIt = false;
+  // *continuesIt is intentionally left unchanged — the prefix keeps its original attachment.
   const auto insertContinuesIt = std::next(continuesIt);
-  wordContinues.insert(insertContinuesIt, originalContinuedToNext);
+  wordContinues.insert(insertContinuesIt, false);
 
-  // Keep the indexed vector in sync if provided
+  // Keep the indexed vector in sync if provided.
   if (continuesVec) {
-    (*continuesVec)[wordIndex] = false;
-    continuesVec->insert(continuesVec->begin() + wordIndex + 1, originalContinuedToNext);
+    // (*continuesVec)[wordIndex] stays unchanged — prefix keeps its attachment.
+    continuesVec->insert(continuesVec->begin() + wordIndex + 1, false);
   }
 
   // Update cached widths to reflect the new prefix/remainder pairing.

lib/Epub/Epub/Section.cpp

@@ -4,12 +4,13 @@
 #include <Logging.h>
 #include <Serialization.h>
 
+#include "Epub/css/CssParser.h"
 #include "Page.h"
 #include "hyphenation/Hyphenator.h"
 #include "parsers/ChapterHtmlSlimParser.h"
 
 namespace {
-constexpr uint8_t SECTION_FILE_VERSION = 12;
+constexpr uint8_t SECTION_FILE_VERSION = 13;
 constexpr uint32_t HEADER_SIZE = sizeof(uint8_t) + sizeof(int) + sizeof(float) + sizeof(bool) + sizeof(uint8_t) +
                                  sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(bool) + sizeof(bool) +
                                  sizeof(uint32_t);
@@ -181,11 +182,26 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
                          viewportHeight, hyphenationEnabled, embeddedStyle);
   std::vector<uint32_t> lut = {};
 
+  // Derive the content base directory and image cache path prefix for the parser
+  size_t lastSlash = localPath.find_last_of('/');
+  std::string contentBase = (lastSlash != std::string::npos) ? localPath.substr(0, lastSlash + 1) : "";
+  std::string imageBasePath = epub->getCachePath() + "/img_" + std::to_string(spineIndex) + "_";
+
+  CssParser* cssParser = nullptr;
+  if (embeddedStyle) {
+    cssParser = epub->getCssParser();
+    if (cssParser) {
+      if (!cssParser->loadFromCache()) {
+        LOG_ERR("SCT", "Failed to load CSS from cache");
+      }
+    }
+  }
+
   ChapterHtmlSlimParser visitor(
-      tmpHtmlPath, renderer, fontId, lineCompression, extraParagraphSpacing, paragraphAlignment, viewportWidth,
+      epub, tmpHtmlPath, renderer, fontId, lineCompression, extraParagraphSpacing, paragraphAlignment, viewportWidth,
       viewportHeight, hyphenationEnabled,
       [this, &lut](std::unique_ptr<Page> page) { lut.emplace_back(this->onPageComplete(std::move(page))); },
-      embeddedStyle, popupFn, embeddedStyle ? epub->getCssParser() : nullptr);
+      embeddedStyle, contentBase, imageBasePath, popupFn, cssParser);
   Hyphenator::setPreferredLanguage(epub->getLanguage());
   success = visitor.parseAndBuildPages();
 
@@ -194,6 +210,9 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
     LOG_ERR("SCT", "Failed to parse XML and build pages");
     file.close();
     Storage.remove(filePath.c_str());
+    if (cssParser) {
+      cssParser->clear();
+    }
     return false;
   }
 
@@ -220,6 +239,9 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
   serialization::writePod(file, pageCount);
   serialization::writePod(file, lutOffset);
   file.close();
+  if (cssParser) {
+    cssParser->clear();
+  }
   return true;
 }
 

lib/Epub/Epub/blocks/Block.h

@@ -8,7 +8,7 @@ typedef enum { TEXT_BLOCK, IMAGE_BLOCK } BlockType;
 class Block {
  public:
   virtual ~Block() = default;
-  virtual void layout(GfxRenderer& renderer) = 0;
+
   virtual BlockType getType() = 0;
   virtual bool isEmpty() = 0;
   virtual void finish() {}

lib/Epub/Epub/blocks/ImageBlock.cpp

@@ -0,0 +1,174 @@
+#include "ImageBlock.h"
+
+#include <GfxRenderer.h>
+#include <Logging.h>
+#include <SDCardManager.h>
+#include <Serialization.h>
+
+#include "../converters/DitherUtils.h"
+#include "../converters/ImageDecoderFactory.h"
+
+// Cache file format:
+// - uint16_t width
+// - uint16_t height
+// - uint8_t pixels[...] - 2 bits per pixel, packed (4 pixels per byte), row-major order
+
+ImageBlock::ImageBlock(const std::string& imagePath, int16_t width, int16_t height)
+    : imagePath(imagePath), width(width), height(height) {}
+
+bool ImageBlock::imageExists() const { return Storage.exists(imagePath.c_str()); }
+
+namespace {
+
+std::string getCachePath(const std::string& imagePath) {
+  // Replace extension with .pxc (pixel cache)
+  size_t dotPos = imagePath.rfind('.');
+  if (dotPos != std::string::npos) {
+    return imagePath.substr(0, dotPos) + ".pxc";
+  }
+  return imagePath + ".pxc";
+}
+
+bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x, int y, int expectedWidth,
+                     int expectedHeight) {
+  FsFile cacheFile;
+  if (!Storage.openFileForRead("IMG", cachePath, cacheFile)) {
+    return false;
+  }
+
+  uint16_t cachedWidth, cachedHeight;
+  if (cacheFile.read(&cachedWidth, 2) != 2 || cacheFile.read(&cachedHeight, 2) != 2) {
+    cacheFile.close();
+    return false;
+  }
+
+  // Verify dimensions are close (allow 1 pixel tolerance for rounding differences)
+  int widthDiff = abs(cachedWidth - expectedWidth);
+  int heightDiff = abs(cachedHeight - expectedHeight);
+  if (widthDiff > 1 || heightDiff > 1) {
+    LOG_ERR("IMG", "Cache dimension mismatch: %dx%d vs %dx%d", cachedWidth, cachedHeight, expectedWidth,
+            expectedHeight);
+    cacheFile.close();
+    return false;
+  }
+
+  // Use cached dimensions for rendering (they're the actual decoded size)
+  expectedWidth = cachedWidth;
+  expectedHeight = cachedHeight;
+
+  LOG_DBG("IMG", "Loading from cache: %s (%dx%d)", cachePath.c_str(), cachedWidth, cachedHeight);
+
+  // Read and render row by row to minimize memory usage
+  const int bytesPerRow = (cachedWidth + 3) / 4;  // 2 bits per pixel, 4 pixels per byte
+  uint8_t* rowBuffer = (uint8_t*)malloc(bytesPerRow);
+  if (!rowBuffer) {
+    LOG_ERR("IMG", "Failed to allocate row buffer");
+    cacheFile.close();
+    return false;
+  }
+
+  for (int row = 0; row < cachedHeight; row++) {
+    if (cacheFile.read(rowBuffer, bytesPerRow) != bytesPerRow) {
+      LOG_ERR("IMG", "Cache read error at row %d", row);
+      free(rowBuffer);
+      cacheFile.close();
+      return false;
+    }
+
+    int destY = y + row;
+    for (int col = 0; col < cachedWidth; col++) {
+      int byteIdx = col / 4;
+      int bitShift = 6 - (col % 4) * 2;  // MSB first within byte
+      uint8_t pixelValue = (rowBuffer[byteIdx] >> bitShift) & 0x03;
+
+      drawPixelWithRenderMode(renderer, x + col, destY, pixelValue);
+    }
+  }
+
+  free(rowBuffer);
+  cacheFile.close();
+  LOG_DBG("IMG", "Cache render complete");
+  return true;
+}
+
+}  // namespace
+
+void ImageBlock::render(GfxRenderer& renderer, const int x, const int y) {
+  LOG_DBG("IMG", "Rendering image at %d,%d: %s (%dx%d)", x, y, imagePath.c_str(), width, height);
+
+  const int screenWidth = renderer.getScreenWidth();
+  const int screenHeight = renderer.getScreenHeight();
+
+  // Bounds check render position using logical screen dimensions
+  if (x < 0 || y < 0 || x + width > screenWidth || y + height > screenHeight) {
+    LOG_ERR("IMG", "Invalid render position: (%d,%d) size (%dx%d) screen (%dx%d)", x, y, width, height, screenWidth,
+            screenHeight);
+    return;
+  }
+
+  // Try to render from cache first
+  std::string cachePath = getCachePath(imagePath);
+  if (renderFromCache(renderer, cachePath, x, y, width, height)) {
+    return;  // Successfully rendered from cache
+  }
+
+  // No cache - need to decode the image
+  // Check if image file exists
+  FsFile file;
+  if (!Storage.openFileForRead("IMG", imagePath, file)) {
+    LOG_ERR("IMG", "Image file not found: %s", imagePath.c_str());
+    return;
+  }
+  size_t fileSize = file.size();
+  file.close();
+
+  if (fileSize == 0) {
+    LOG_ERR("IMG", "Image file is empty: %s", imagePath.c_str());
+    return;
+  }
+
+  LOG_DBG("IMG", "Decoding and caching: %s", imagePath.c_str());
+
+  RenderConfig config;
+  config.x = x;
+  config.y = y;
+  config.maxWidth = width;
+  config.maxHeight = height;
+  config.useGrayscale = true;
+  config.useDithering = true;
+  config.performanceMode = false;
+  config.useExactDimensions = true;  // Use pre-calculated dimensions to avoid rounding mismatches
+  config.cachePath = cachePath;      // Enable caching during decode
+
+  ImageToFramebufferDecoder* decoder = ImageDecoderFactory::getDecoder(imagePath);
+  if (!decoder) {
+    LOG_ERR("IMG", "No decoder found for image: %s", imagePath.c_str());
+    return;
+  }
+
+  LOG_DBG("IMG", "Using %s decoder", decoder->getFormatName());
+
+  bool success = decoder->decodeToFramebuffer(imagePath, renderer, config);
+  if (!success) {
+    LOG_ERR("IMG", "Failed to decode image: %s", imagePath.c_str());
+    return;
+  }
+
+  LOG_DBG("IMG", "Decode successful");
+}
+
+bool ImageBlock::serialize(FsFile& file) {
+  serialization::writeString(file, imagePath);
+  serialization::writePod(file, width);
+  serialization::writePod(file, height);
+  return true;
+}
+
+std::unique_ptr<ImageBlock> ImageBlock::deserialize(FsFile& file) {
+  std::string path;
+  serialization::readString(file, path);
+  int16_t w, h;
+  serialization::readPod(file, w);
+  serialization::readPod(file, h);
+  return std::unique_ptr<ImageBlock>(new ImageBlock(path, w, h));
+}

lib/Epub/Epub/blocks/ImageBlock.h

@@ -0,0 +1,31 @@
+#pragma once
+#include <SdFat.h>
+
+#include <memory>
+#include <string>
+
+#include "Block.h"
+
+class ImageBlock final : public Block {
+ public:
+  ImageBlock(const std::string& imagePath, int16_t width, int16_t height);
+  ~ImageBlock() override = default;
+
+  const std::string& getImagePath() const { return imagePath; }
+  int16_t getWidth() const { return width; }
+  int16_t getHeight() const { return height; }
+
+  bool imageExists() const;
+
+  BlockType getType() override { return IMAGE_BLOCK; }
+  bool isEmpty() override { return false; }
+
+  void render(GfxRenderer& renderer, const int x, const int y);
+  bool serialize(FsFile& file);
+  static std::unique_ptr<ImageBlock> deserialize(FsFile& file);
+
+ private:
+  std::string imagePath;
+  int16_t width;
+  int16_t height;
+};

lib/Epub/Epub/blocks/TextBlock.cpp

@@ -33,7 +33,7 @@ void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int
       if (w.size() >= 3 && static_cast<uint8_t>(w[0]) == 0xE2 && static_cast<uint8_t>(w[1]) == 0x80 &&
           static_cast<uint8_t>(w[2]) == 0x83) {
         const char* visiblePtr = w.c_str() + 3;
-        const int prefixWidth = renderer.getTextAdvanceX(fontId, std::string("\xe2\x80\x83").c_str());
+        const int prefixWidth = renderer.getTextAdvanceX(fontId, "\xe2\x80\x83", currentStyle);
         const int visibleWidth = renderer.getTextWidth(fontId, visiblePtr, currentStyle);
         startX = wordX + prefixWidth;
         underlineWidth = visibleWidth;

lib/Epub/Epub/blocks/TextBlock.h

@@ -28,7 +28,6 @@ class TextBlock final : public Block {
   void setBlockStyle(const BlockStyle& blockStyle) { this->blockStyle = blockStyle; }
   const BlockStyle& getBlockStyle() const { return blockStyle; }
   bool isEmpty() override { return words.empty(); }
-  void layout(GfxRenderer& renderer) override {};
   // given a renderer works out where to break the words into lines
   void render(const GfxRenderer& renderer, int fontId, int x, int y) const;
   BlockType getType() override { return TEXT_BLOCK; }

lib/Epub/Epub/converters/DitherUtils.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <GfxRenderer.h>
+#include <stdint.h>
+
+// 4x4 Bayer matrix for ordered dithering
+inline const uint8_t bayer4x4[4][4] = {
+    {0, 8, 2, 10},
+    {12, 4, 14, 6},
+    {3, 11, 1, 9},
+    {15, 7, 13, 5},
+};
+
+// Apply Bayer dithering and quantize to 4 levels (0-3)
+// Stateless - works correctly with any pixel processing order
+inline uint8_t applyBayerDither4Level(uint8_t gray, int x, int y) {
+  int bayer = bayer4x4[y & 3][x & 3];
+  int dither = (bayer - 8) * 5;  // Scale to +/-40 (half of quantization step 85)
+
+  int adjusted = gray + dither;
+  if (adjusted < 0) adjusted = 0;
+  if (adjusted > 255) adjusted = 255;
+
+  if (adjusted < 64) return 0;
+  if (adjusted < 128) return 1;
+  if (adjusted < 192) return 2;
+  return 3;
+}
+
+// Draw a pixel respecting the current render mode for grayscale support
+inline void drawPixelWithRenderMode(GfxRenderer& renderer, int x, int y, uint8_t pixelValue) {
+  GfxRenderer::RenderMode renderMode = renderer.getRenderMode();
+  if (renderMode == GfxRenderer::BW && pixelValue < 3) {
+    renderer.drawPixel(x, y, true);
+  } else if (renderMode == GfxRenderer::GRAYSCALE_MSB && (pixelValue == 1 || pixelValue == 2)) {
+    renderer.drawPixel(x, y, false);
+  } else if (renderMode == GfxRenderer::GRAYSCALE_LSB && pixelValue == 1) {
+    renderer.drawPixel(x, y, false);
+  }
+}

lib/Epub/Epub/converters/ImageDecoderFactory.cpp

@@ -0,0 +1,42 @@
+#include "ImageDecoderFactory.h"
+
+#include <Logging.h>
+
+#include <memory>
+#include <string>
+
+#include "JpegToFramebufferConverter.h"
+#include "PngToFramebufferConverter.h"
+
+std::unique_ptr<JpegToFramebufferConverter> ImageDecoderFactory::jpegDecoder = nullptr;
+std::unique_ptr<PngToFramebufferConverter> ImageDecoderFactory::pngDecoder = nullptr;
+
+ImageToFramebufferDecoder* ImageDecoderFactory::getDecoder(const std::string& imagePath) {
+  std::string ext = imagePath;
+  size_t dotPos = ext.rfind('.');
+  if (dotPos != std::string::npos) {
+    ext = ext.substr(dotPos);
+    for (auto& c : ext) {
+      c = tolower(c);
+    }
+  } else {
+    ext = "";
+  }
+
+  if (JpegToFramebufferConverter::supportsFormat(ext)) {
+    if (!jpegDecoder) {
+      jpegDecoder.reset(new JpegToFramebufferConverter());
+    }
+    return jpegDecoder.get();
+  } else if (PngToFramebufferConverter::supportsFormat(ext)) {
+    if (!pngDecoder) {
+      pngDecoder.reset(new PngToFramebufferConverter());
+    }
+    return pngDecoder.get();
+  }
+
+  LOG_ERR("DEC", "No decoder found for image: %s", imagePath.c_str());
+  return nullptr;
+}
+
+bool ImageDecoderFactory::isFormatSupported(const std::string& imagePath) { return getDecoder(imagePath) != nullptr; }

lib/Epub/Epub/converters/ImageDecoderFactory.h

@@ -0,0 +1,20 @@
+#pragma once
+#include <cstdint>
+#include <memory>
+#include <string>
+
+#include "ImageToFramebufferDecoder.h"
+
+class JpegToFramebufferConverter;
+class PngToFramebufferConverter;
+
+class ImageDecoderFactory {
+ public:
+  // Returns non-owning pointer - factory owns the decoder lifetime
+  static ImageToFramebufferDecoder* getDecoder(const std::string& imagePath);
+  static bool isFormatSupported(const std::string& imagePath);
+
+ private:
+  static std::unique_ptr<JpegToFramebufferConverter> jpegDecoder;
+  static std::unique_ptr<PngToFramebufferConverter> pngDecoder;
+};

lib/Epub/Epub/converters/ImageToFramebufferDecoder.cpp

@@ -0,0 +1,17 @@
+#include "ImageToFramebufferDecoder.h"
+
+#include <Logging.h>
+
+bool ImageToFramebufferDecoder::validateImageDimensions(int width, int height, const std::string& format) {
+  if (width * height > MAX_SOURCE_PIXELS) {
+    LOG_ERR("IMG", "Image too large (%dx%d = %d pixels %s), max supported: %d pixels", width, height, width * height,
+            format.c_str(), MAX_SOURCE_PIXELS);
+    return false;
+  }
+  return true;
+}
+
+void ImageToFramebufferDecoder::warnUnsupportedFeature(const std::string& feature, const std::string& imagePath) {
+  LOG_ERR("IMG", "Warning: Unsupported feature '%s' in image '%s'. Image may not display correctly.", feature.c_str(),
+          imagePath.c_str());
+}

lib/Epub/Epub/converters/ImageToFramebufferDecoder.h

@@ -0,0 +1,40 @@
+#pragma once
+#include <SdFat.h>
+
+#include <memory>
+#include <string>
+
+class GfxRenderer;
+
+struct ImageDimensions {
+  int16_t width;
+  int16_t height;
+};
+
+struct RenderConfig {
+  int x, y;
+  int maxWidth, maxHeight;
+  bool useGrayscale = true;
+  bool useDithering = true;
+  bool performanceMode = false;
+  bool useExactDimensions = false;  // If true, use maxWidth/maxHeight as exact output size (no recalculation)
+  std::string cachePath;            // If non-empty, decoder will write pixel cache to this path
+};
+
+class ImageToFramebufferDecoder {
+ public:
+  virtual ~ImageToFramebufferDecoder() = default;
+
+  virtual bool decodeToFramebuffer(const std::string& imagePath, GfxRenderer& renderer, const RenderConfig& config) = 0;
+
+  virtual bool getDimensions(const std::string& imagePath, ImageDimensions& dims) const = 0;
+
+  virtual const char* getFormatName() const = 0;
+
+ protected:
+  // Size validation helpers
+  static constexpr int MAX_SOURCE_PIXELS = 3145728;  // 2048 * 1536
+
+  bool validateImageDimensions(int width, int height, const std::string& format);
+  void warnUnsupportedFeature(const std::string& feature, const std::string& imagePath);
+};

lib/Epub/Epub/converters/JpegToFramebufferConverter.cpp

@@ -0,0 +1,297 @@
+#include "JpegToFramebufferConverter.h"
+
+#include <GfxRenderer.h>
+#include <Logging.h>
+#include <SDCardManager.h>
+#include <SdFat.h>
+#include <picojpeg.h>
+
+#include <cstdio>
+#include <cstring>
+
+#include "DitherUtils.h"
+#include "PixelCache.h"
+
+struct JpegContext {
+  FsFile& file;
+  uint8_t buffer[512];
+  size_t bufferPos;
+  size_t bufferFilled;
+  JpegContext(FsFile& f) : file(f), bufferPos(0), bufferFilled(0) {}
+};
+
+bool JpegToFramebufferConverter::getDimensionsStatic(const std::string& imagePath, ImageDimensions& out) {
+  FsFile file;
+  if (!Storage.openFileForRead("JPG", imagePath, file)) {
+    LOG_ERR("JPG", "Failed to open file for dimensions: %s", imagePath.c_str());
+    return false;
+  }
+
+  JpegContext context(file);
+  pjpeg_image_info_t imageInfo;
+
+  int status = pjpeg_decode_init(&imageInfo, jpegReadCallback, &context, 0);
+  file.close();
+
+  if (status != 0) {
+    LOG_ERR("JPG", "Failed to init JPEG for dimensions: %d", status);
+    return false;
+  }
+
+  out.width = imageInfo.m_width;
+  out.height = imageInfo.m_height;
+  LOG_DBG("JPG", "Image dimensions: %dx%d", out.width, out.height);
+  return true;
+}
+
+bool JpegToFramebufferConverter::decodeToFramebuffer(const std::string& imagePath, GfxRenderer& renderer,
+                                                     const RenderConfig& config) {
+  LOG_DBG("JPG", "Decoding JPEG: %s", imagePath.c_str());
+
+  FsFile file;
+  if (!Storage.openFileForRead("JPG", imagePath, file)) {
+    LOG_ERR("JPG", "Failed to open file: %s", imagePath.c_str());
+    return false;
+  }
+
+  JpegContext context(file);
+  pjpeg_image_info_t imageInfo;
+
+  int status = pjpeg_decode_init(&imageInfo, jpegReadCallback, &context, 0);
+  if (status != 0) {
+    LOG_ERR("JPG", "picojpeg init failed: %d", status);
+    file.close();
+    return false;
+  }
+
+  if (!validateImageDimensions(imageInfo.m_width, imageInfo.m_height, "JPEG")) {
+    file.close();
+    return false;
+  }
+
+  // Calculate output dimensions
+  int destWidth, destHeight;
+  float scale;
+
+  if (config.useExactDimensions && config.maxWidth > 0 && config.maxHeight > 0) {
+    // Use exact dimensions as specified (avoids rounding mismatches with pre-calculated sizes)
+    destWidth = config.maxWidth;
+    destHeight = config.maxHeight;
+    scale = (float)destWidth / imageInfo.m_width;
+  } else {
+    // Calculate scale factor to fit within maxWidth/maxHeight
+    float scaleX = (config.maxWidth > 0 && imageInfo.m_width > config.maxWidth)
+                       ? (float)config.maxWidth / imageInfo.m_width
+                       : 1.0f;
+    float scaleY = (config.maxHeight > 0 && imageInfo.m_height > config.maxHeight)
+                       ? (float)config.maxHeight / imageInfo.m_height
+                       : 1.0f;
+    scale = (scaleX < scaleY) ? scaleX : scaleY;
+    if (scale > 1.0f) scale = 1.0f;
+
+    destWidth = (int)(imageInfo.m_width * scale);
+    destHeight = (int)(imageInfo.m_height * scale);
+  }
+
+  LOG_DBG("JPG", "JPEG %dx%d -> %dx%d (scale %.2f), scan type: %d, MCU: %dx%d", imageInfo.m_width, imageInfo.m_height,
+          destWidth, destHeight, scale, imageInfo.m_scanType, imageInfo.m_MCUWidth, imageInfo.m_MCUHeight);
+
+  if (!imageInfo.m_pMCUBufR || !imageInfo.m_pMCUBufG || !imageInfo.m_pMCUBufB) {
+    LOG_ERR("JPG", "Null buffer pointers in imageInfo");
+    file.close();
+    return false;
+  }
+
+  const int screenWidth = renderer.getScreenWidth();
+  const int screenHeight = renderer.getScreenHeight();
+
+  // Allocate pixel cache if cachePath is provided
+  PixelCache cache;
+  bool caching = !config.cachePath.empty();
+  if (caching) {
+    if (!cache.allocate(destWidth, destHeight, config.x, config.y)) {
+      LOG_ERR("JPG", "Failed to allocate cache buffer, continuing without caching");
+      caching = false;
+    }
+  }
+
+  int mcuX = 0;
+  int mcuY = 0;
+
+  while (mcuY < imageInfo.m_MCUSPerCol) {
+    status = pjpeg_decode_mcu();
+    if (status == PJPG_NO_MORE_BLOCKS) {
+      break;
+    }
+    if (status != 0) {
+      LOG_ERR("JPG", "MCU decode failed: %d", status);
+      file.close();
+      return false;
+    }
+
+    // Source position in image coordinates
+    int srcStartX = mcuX * imageInfo.m_MCUWidth;
+    int srcStartY = mcuY * imageInfo.m_MCUHeight;
+
+    switch (imageInfo.m_scanType) {
+      case PJPG_GRAYSCALE:
+        for (int row = 0; row < 8; row++) {
+          int srcY = srcStartY + row;
+          int destY = config.y + (int)(srcY * scale);
+          if (destY >= screenHeight || destY >= config.y + destHeight) continue;
+          for (int col = 0; col < 8; col++) {
+            int srcX = srcStartX + col;
+            int destX = config.x + (int)(srcX * scale);
+            if (destX >= screenWidth || destX >= config.x + destWidth) continue;
+            uint8_t gray = imageInfo.m_pMCUBufR[row * 8 + col];
+            uint8_t dithered = config.useDithering ? applyBayerDither4Level(gray, destX, destY) : gray / 85;
+            if (dithered > 3) dithered = 3;
+            drawPixelWithRenderMode(renderer, destX, destY, dithered);
+            if (caching) cache.setPixel(destX, destY, dithered);
+          }
+        }
+        break;
+
+      case PJPG_YH1V1:
+        for (int row = 0; row < 8; row++) {
+          int srcY = srcStartY + row;
+          int destY = config.y + (int)(srcY * scale);
+          if (destY >= screenHeight || destY >= config.y + destHeight) continue;
+          for (int col = 0; col < 8; col++) {
+            int srcX = srcStartX + col;
+            int destX = config.x + (int)(srcX * scale);
+            if (destX >= screenWidth || destX >= config.x + destWidth) continue;
+            uint8_t r = imageInfo.m_pMCUBufR[row * 8 + col];
+            uint8_t g = imageInfo.m_pMCUBufG[row * 8 + col];
+            uint8_t b = imageInfo.m_pMCUBufB[row * 8 + col];
+            uint8_t gray = (uint8_t)((r * 77 + g * 150 + b * 29) >> 8);
+            uint8_t dithered = config.useDithering ? applyBayerDither4Level(gray, destX, destY) : gray / 85;
+            if (dithered > 3) dithered = 3;
+            drawPixelWithRenderMode(renderer, destX, destY, dithered);
+            if (caching) cache.setPixel(destX, destY, dithered);
+          }
+        }
+        break;
+
+      case PJPG_YH2V1:
+        for (int row = 0; row < 8; row++) {
+          int srcY = srcStartY + row;
+          int destY = config.y + (int)(srcY * scale);
+          if (destY >= screenHeight || destY >= config.y + destHeight) continue;
+          for (int col = 0; col < 16; col++) {
+            int srcX = srcStartX + col;
+            int destX = config.x + (int)(srcX * scale);
+            if (destX >= screenWidth || destX >= config.x + destWidth) continue;
+            int blockIndex = (col < 8) ? 0 : 1;
+            int pixelIndex = row * 8 + (col % 8);
+            uint8_t r = imageInfo.m_pMCUBufR[blockIndex * 64 + pixelIndex];
+            uint8_t g = imageInfo.m_pMCUBufG[blockIndex * 64 + pixelIndex];
+            uint8_t b = imageInfo.m_pMCUBufB[blockIndex * 64 + pixelIndex];
+            uint8_t gray = (uint8_t)((r * 77 + g * 150 + b * 29) >> 8);
+            uint8_t dithered = config.useDithering ? applyBayerDither4Level(gray, destX, destY) : gray / 85;
+            if (dithered > 3) dithered = 3;
+            drawPixelWithRenderMode(renderer, destX, destY, dithered);
+            if (caching) cache.setPixel(destX, destY, dithered);
+          }
+        }
+        break;
+
+      case PJPG_YH1V2:
+        for (int row = 0; row < 16; row++) {
+          int srcY = srcStartY + row;
+          int destY = config.y + (int)(srcY * scale);
+          if (destY >= screenHeight || destY >= config.y + destHeight) continue;
+          for (int col = 0; col < 8; col++) {
+            int srcX = srcStartX + col;
+            int destX = config.x + (int)(srcX * scale);
+            if (destX >= screenWidth || destX >= config.x + destWidth) continue;
+            int blockIndex = (row < 8) ? 0 : 1;
+            int pixelIndex = (row % 8) * 8 + col;
+            uint8_t r = imageInfo.m_pMCUBufR[blockIndex * 128 + pixelIndex];
+            uint8_t g = imageInfo.m_pMCUBufG[blockIndex * 128 + pixelIndex];
+            uint8_t b = imageInfo.m_pMCUBufB[blockIndex * 128 + pixelIndex];
+            uint8_t gray = (uint8_t)((r * 77 + g * 150 + b * 29) >> 8);
+            uint8_t dithered = config.useDithering ? applyBayerDither4Level(gray, destX, destY) : gray / 85;
+            if (dithered > 3) dithered = 3;
+            drawPixelWithRenderMode(renderer, destX, destY, dithered);
+            if (caching) cache.setPixel(destX, destY, dithered);
+          }
+        }
+        break;
+
+      case PJPG_YH2V2:
+        for (int row = 0; row < 16; row++) {
+          int srcY = srcStartY + row;
+          int destY = config.y + (int)(srcY * scale);
+          if (destY >= screenHeight || destY >= config.y + destHeight) continue;
+          for (int col = 0; col < 16; col++) {
+            int srcX = srcStartX + col;
+            int destX = config.x + (int)(srcX * scale);
+            if (destX >= screenWidth || destX >= config.x + destWidth) continue;
+            int blockX = (col < 8) ? 0 : 1;
+            int blockY = (row < 8) ? 0 : 1;
+            int blockIndex = blockY * 2 + blockX;
+            int pixelIndex = (row % 8) * 8 + (col % 8);
+            int blockOffset = blockIndex * 64;
+            uint8_t r = imageInfo.m_pMCUBufR[blockOffset + pixelIndex];
+            uint8_t g = imageInfo.m_pMCUBufG[blockOffset + pixelIndex];
+            uint8_t b = imageInfo.m_pMCUBufB[blockOffset + pixelIndex];
+            uint8_t gray = (uint8_t)((r * 77 + g * 150 + b * 29) >> 8);
+            uint8_t dithered = config.useDithering ? applyBayerDither4Level(gray, destX, destY) : gray / 85;
+            if (dithered > 3) dithered = 3;
+            drawPixelWithRenderMode(renderer, destX, destY, dithered);
+            if (caching) cache.setPixel(destX, destY, dithered);
+          }
+        }
+        break;
+    }
+
+    mcuX++;
+    if (mcuX >= imageInfo.m_MCUSPerRow) {
+      mcuX = 0;
+      mcuY++;
+    }
+  }
+
+  LOG_DBG("JPG", "Decoding complete");
+  file.close();
+
+  // Write cache file if caching was enabled
+  if (caching) {
+    cache.writeToFile(config.cachePath);
+  }
+
+  return true;
+}
+
+unsigned char JpegToFramebufferConverter::jpegReadCallback(unsigned char* pBuf, unsigned char buf_size,
+                                                           unsigned char* pBytes_actually_read, void* pCallback_data) {
+  JpegContext* context = reinterpret_cast<JpegContext*>(pCallback_data);
+
+  if (context->bufferPos >= context->bufferFilled) {
+    int readCount = context->file.read(context->buffer, sizeof(context->buffer));
+    if (readCount <= 0) {
+      *pBytes_actually_read = 0;
+      return 0;
+    }
+    context->bufferFilled = readCount;
+    context->bufferPos = 0;
+  }
+
+  unsigned int bytesAvailable = context->bufferFilled - context->bufferPos;
+  unsigned int bytesToCopy = (bytesAvailable < buf_size) ? bytesAvailable : buf_size;
+
+  memcpy(pBuf, &context->buffer[context->bufferPos], bytesToCopy);
+  context->bufferPos += bytesToCopy;
+  *pBytes_actually_read = bytesToCopy;
+
+  return 0;
+}
+
+bool JpegToFramebufferConverter::supportsFormat(const std::string& extension) {
+  std::string ext = extension;
+  for (auto& c : ext) {
+    c = tolower(c);
+  }
+  return (ext == ".jpg" || ext == ".jpeg");
+}

lib/Epub/Epub/converters/JpegToFramebufferConverter.h

@@ -0,0 +1,24 @@
+#pragma once
+#include <stdint.h>
+
+#include <string>
+
+#include "ImageToFramebufferDecoder.h"
+
+class JpegToFramebufferConverter final : public ImageToFramebufferDecoder {
+ public:
+  static bool getDimensionsStatic(const std::string& imagePath, ImageDimensions& out);
+
+  bool decodeToFramebuffer(const std::string& imagePath, GfxRenderer& renderer, const RenderConfig& config) override;
+
+  bool getDimensions(const std::string& imagePath, ImageDimensions& dims) const override {
+    return getDimensionsStatic(imagePath, dims);
+  }
+
+  static bool supportsFormat(const std::string& extension);
+  const char* getFormatName() const override { return "JPEG"; }
+
+ private:
+  static unsigned char jpegReadCallback(unsigned char* pBuf, unsigned char buf_size,
+                                        unsigned char* pBytes_actually_read, void* pCallback_data);
+};

lib/Epub/Epub/converters/PixelCache.h

@@ -0,0 +1,82 @@
+#pragma once
+
+#include <HalStorage.h>
+#include <Logging.h>
+#include <stdint.h>
+
+#include <cstring>
+#include <string>
+
+// Cache buffer for storing 2-bit pixels (4 levels) during decode.
+// Packs 4 pixels per byte, MSB first.
+struct PixelCache {
+  uint8_t* buffer;
+  int width;
+  int height;
+  int bytesPerRow;
+  int originX;  // config.x - to convert screen coords to cache coords
+  int originY;  // config.y
+
+  PixelCache() : buffer(nullptr), width(0), height(0), bytesPerRow(0), originX(0), originY(0) {}
+  PixelCache(const PixelCache&) = delete;
+  PixelCache& operator=(const PixelCache&) = delete;
+
+  static constexpr size_t MAX_CACHE_BYTES = 256 * 1024;  // 256KB limit for embedded targets
+
+  bool allocate(int w, int h, int ox, int oy) {
+    width = w;
+    height = h;
+    originX = ox;
+    originY = oy;
+    bytesPerRow = (w + 3) / 4;  // 2 bits per pixel, 4 pixels per byte
+    size_t bufferSize = (size_t)bytesPerRow * h;
+    if (bufferSize > MAX_CACHE_BYTES) {
+      LOG_ERR("IMG", "Cache buffer too large: %d bytes for %dx%d (limit %d)", bufferSize, w, h, MAX_CACHE_BYTES);
+      return false;
+    }
+    buffer = (uint8_t*)malloc(bufferSize);
+    if (buffer) {
+      memset(buffer, 0, bufferSize);
+      LOG_DBG("IMG", "Allocated cache buffer: %d bytes for %dx%d", bufferSize, w, h);
+    }
+    return buffer != nullptr;
+  }
+
+  void setPixel(int screenX, int screenY, uint8_t value) {
+    if (!buffer) return;
+    int localX = screenX - originX;
+    int localY = screenY - originY;
+    if (localX < 0 || localX >= width || localY < 0 || localY >= height) return;
+
+    int byteIdx = localY * bytesPerRow + localX / 4;
+    int bitShift = 6 - (localX % 4) * 2;  // MSB first: pixel 0 at bits 6-7
+    buffer[byteIdx] = (buffer[byteIdx] & ~(0x03 << bitShift)) | ((value & 0x03) << bitShift);
+  }
+
+  bool writeToFile(const std::string& cachePath) {
+    if (!buffer) return false;
+
+    FsFile cacheFile;
+    if (!Storage.openFileForWrite("IMG", cachePath, cacheFile)) {
+      LOG_ERR("IMG", "Failed to open cache file for writing: %s", cachePath.c_str());
+      return false;
+    }
+
+    uint16_t w = width;
+    uint16_t h = height;
+    cacheFile.write(&w, 2);
+    cacheFile.write(&h, 2);
+    cacheFile.write(buffer, bytesPerRow * height);
+    cacheFile.close();
+
+    LOG_DBG("IMG", "Cache written: %s (%dx%d, %d bytes)", cachePath.c_str(), width, height, 4 + bytesPerRow * height);
+    return true;
+  }
+
+  ~PixelCache() {
+    if (buffer) {
+      free(buffer);
+      buffer = nullptr;
+    }
+  }
+};

lib/Epub/Epub/converters/PngToFramebufferConverter.cpp

@@ -0,0 +1,400 @@
+#include "PngToFramebufferConverter.h"
+
+#include <GfxRenderer.h>
+#include <Logging.h>
+#include <PNGdec.h>
+#include <SDCardManager.h>
+#include <SdFat.h>
+
+#include <cstdlib>
+#include <new>
+
+#include "DitherUtils.h"
+#include "PixelCache.h"
+
+namespace {
+
+// Context struct passed through PNGdec callbacks to avoid global mutable state.
+// The draw callback receives this via pDraw->pUser (set by png.decode()).
+// The file I/O callbacks receive the FsFile* via pFile->fHandle (set by pngOpen()).
+struct PngContext {
+  GfxRenderer* renderer;
+  const RenderConfig* config;
+  int screenWidth;
+  int screenHeight;
+
+  // Scaling state
+  float scale;
+  int srcWidth;
+  int srcHeight;
+  int dstWidth;
+  int dstHeight;
+  int lastDstY;  // Track last rendered destination Y to avoid duplicates
+
+  PixelCache cache;
+  bool caching;
+
+  uint8_t* grayLineBuffer;
+
+  PngContext()
+      : renderer(nullptr),
+        config(nullptr),
+        screenWidth(0),
+        screenHeight(0),
+        scale(1.0f),
+        srcWidth(0),
+        srcHeight(0),
+        dstWidth(0),
+        dstHeight(0),
+        lastDstY(-1),
+        caching(false),
+        grayLineBuffer(nullptr) {}
+};
+
+// File I/O callbacks use pFile->fHandle to access the FsFile*,
+// avoiding the need for global file state.
+void* pngOpenWithHandle(const char* filename, int32_t* size) {
+  FsFile* f = new FsFile();
+  if (!Storage.openFileForRead("PNG", std::string(filename), *f)) {
+    delete f;
+    return nullptr;
+  }
+  *size = f->size();
+  return f;
+}
+
+void pngCloseWithHandle(void* handle) {
+  FsFile* f = reinterpret_cast<FsFile*>(handle);
+  if (f) {
+    f->close();
+    delete f;
+  }
+}
+
+int32_t pngReadWithHandle(PNGFILE* pFile, uint8_t* pBuf, int32_t len) {
+  FsFile* f = reinterpret_cast<FsFile*>(pFile->fHandle);
+  if (!f) return 0;
+  return f->read(pBuf, len);
+}
+
+int32_t pngSeekWithHandle(PNGFILE* pFile, int32_t pos) {
+  FsFile* f = reinterpret_cast<FsFile*>(pFile->fHandle);
+  if (!f) return -1;
+  return f->seek(pos);
+}
+
+// The PNG decoder (PNGdec) is ~42 KB due to internal zlib decompression buffers.
+// We heap-allocate it on demand rather than using a static instance, so this memory
+// is only consumed while actually decoding/querying PNG images. This is critical on
+// the ESP32-C3 where total RAM is ~320 KB.
+constexpr size_t PNG_DECODER_APPROX_SIZE = 44 * 1024;                          // ~42 KB + overhead
+constexpr size_t MIN_FREE_HEAP_FOR_PNG = PNG_DECODER_APPROX_SIZE + 16 * 1024;  // decoder + 16 KB headroom
+
+// PNGdec keeps TWO scanlines in its internal ucPixels buffer (current + previous)
+// and each scanline includes a leading filter byte.
+// Required storage is therefore approximately: 2 * (pitch + 1) + alignment slack.
+// If PNG_MAX_BUFFERED_PIXELS is smaller than this requirement for a given image,
+// PNGdec can overrun its internal buffer before our draw callback executes.
+int bytesPerPixelFromType(int pixelType) {
+  switch (pixelType) {
+    case PNG_PIXEL_TRUECOLOR:
+      return 3;
+    case PNG_PIXEL_GRAY_ALPHA:
+      return 2;
+    case PNG_PIXEL_TRUECOLOR_ALPHA:
+      return 4;
+    case PNG_PIXEL_GRAYSCALE:
+    case PNG_PIXEL_INDEXED:
+    default:
+      return 1;
+  }
+}
+
+int requiredPngInternalBufferBytes(int srcWidth, int pixelType) {
+  // +1 filter byte per scanline, *2 for current+previous lines, +32 for alignment margin.
+  int pitch = srcWidth * bytesPerPixelFromType(pixelType);
+  return ((pitch + 1) * 2) + 32;
+}
+
+// Convert entire source line to grayscale with alpha blending to white background.
+// For indexed PNGs with tRNS chunk, alpha values are stored at palette[768] onwards.
+// Processing the whole line at once improves cache locality and reduces per-pixel overhead.
+void convertLineToGray(uint8_t* pPixels, uint8_t* grayLine, int width, int pixelType, uint8_t* palette, int hasAlpha) {
+  switch (pixelType) {
+    case PNG_PIXEL_GRAYSCALE:
+      memcpy(grayLine, pPixels, width);
+      break;
+
+    case PNG_PIXEL_TRUECOLOR:
+      for (int x = 0; x < width; x++) {
+        uint8_t* p = &pPixels[x * 3];
+        grayLine[x] = (uint8_t)((p[0] * 77 + p[1] * 150 + p[2] * 29) >> 8);
+      }
+      break;
+
+    case PNG_PIXEL_INDEXED:
+      if (palette) {
+        if (hasAlpha) {
+          for (int x = 0; x < width; x++) {
+            uint8_t idx = pPixels[x];
+            uint8_t* p = &palette[idx * 3];
+            uint8_t gray = (uint8_t)((p[0] * 77 + p[1] * 150 + p[2] * 29) >> 8);
+            uint8_t alpha = palette[768 + idx];
+            grayLine[x] = (uint8_t)((gray * alpha + 255 * (255 - alpha)) / 255);
+          }
+        } else {
+          for (int x = 0; x < width; x++) {
+            uint8_t* p = &palette[pPixels[x] * 3];
+            grayLine[x] = (uint8_t)((p[0] * 77 + p[1] * 150 + p[2] * 29) >> 8);
+          }
+        }
+      } else {
+        memcpy(grayLine, pPixels, width);
+      }
+      break;
+
+    case PNG_PIXEL_GRAY_ALPHA:
+      for (int x = 0; x < width; x++) {
+        uint8_t gray = pPixels[x * 2];
+        uint8_t alpha = pPixels[x * 2 + 1];
+        grayLine[x] = (uint8_t)((gray * alpha + 255 * (255 - alpha)) / 255);
+      }
+      break;
+
+    case PNG_PIXEL_TRUECOLOR_ALPHA:
+      for (int x = 0; x < width; x++) {
+        uint8_t* p = &pPixels[x * 4];
+        uint8_t gray = (uint8_t)((p[0] * 77 + p[1] * 150 + p[2] * 29) >> 8);
+        uint8_t alpha = p[3];
+        grayLine[x] = (uint8_t)((gray * alpha + 255 * (255 - alpha)) / 255);
+      }
+      break;
+
+    default:
+      memset(grayLine, 128, width);
+      break;
+  }
+}
+
+int pngDrawCallback(PNGDRAW* pDraw) {
+  PngContext* ctx = reinterpret_cast<PngContext*>(pDraw->pUser);
+  if (!ctx || !ctx->config || !ctx->renderer || !ctx->grayLineBuffer) return 0;
+
+  int srcY = pDraw->y;
+  int srcWidth = ctx->srcWidth;
+
+  // Calculate destination Y with scaling
+  int dstY = (int)(srcY * ctx->scale);
+
+  // Skip if we already rendered this destination row (multiple source rows map to same dest)
+  if (dstY == ctx->lastDstY) return 1;
+  ctx->lastDstY = dstY;
+
+  // Check bounds
+  if (dstY >= ctx->dstHeight) return 1;
+
+  int outY = ctx->config->y + dstY;
+  if (outY >= ctx->screenHeight) return 1;
+
+  // Convert entire source line to grayscale (improves cache locality)
+  convertLineToGray(pDraw->pPixels, ctx->grayLineBuffer, srcWidth, pDraw->iPixelType, pDraw->pPalette,
+                    pDraw->iHasAlpha);
+
+  // Render scaled row using Bresenham-style integer stepping (no floating-point division)
+  int dstWidth = ctx->dstWidth;
+  int outXBase = ctx->config->x;
+  int screenWidth = ctx->screenWidth;
+  bool useDithering = ctx->config->useDithering;
+  bool caching = ctx->caching;
+
+  int srcX = 0;
+  int error = 0;
+
+  for (int dstX = 0; dstX < dstWidth; dstX++) {
+    int outX = outXBase + dstX;
+    if (outX < screenWidth) {
+      uint8_t gray = ctx->grayLineBuffer[srcX];
+
+      uint8_t ditheredGray;
+      if (useDithering) {
+        ditheredGray = applyBayerDither4Level(gray, outX, outY);
+      } else {
+        ditheredGray = gray / 85;
+        if (ditheredGray > 3) ditheredGray = 3;
+      }
+      drawPixelWithRenderMode(*ctx->renderer, outX, outY, ditheredGray);
+      if (caching) ctx->cache.setPixel(outX, outY, ditheredGray);
+    }
+
+    // Bresenham-style stepping: advance srcX based on ratio srcWidth/dstWidth
+    error += srcWidth;
+    while (error >= dstWidth) {
+      error -= dstWidth;
+      srcX++;
+    }
+  }
+
+  return 1;
+}
+
+}  // namespace
+
+bool PngToFramebufferConverter::getDimensionsStatic(const std::string& imagePath, ImageDimensions& out) {
+  size_t freeHeap = ESP.getFreeHeap();
+  if (freeHeap < MIN_FREE_HEAP_FOR_PNG) {
+    LOG_ERR("PNG", "Not enough heap for PNG decoder (%u free, need %u)", freeHeap, MIN_FREE_HEAP_FOR_PNG);
+    return false;
+  }
+
+  PNG* png = new (std::nothrow) PNG();
+  if (!png) {
+    LOG_ERR("PNG", "Failed to allocate PNG decoder for dimensions");
+    return false;
+  }
+
+  int rc = png->open(imagePath.c_str(), pngOpenWithHandle, pngCloseWithHandle, pngReadWithHandle, pngSeekWithHandle,
+                     nullptr);
+
+  if (rc != 0) {
+    LOG_ERR("PNG", "Failed to open PNG for dimensions: %d", rc);
+    delete png;
+    return false;
+  }
+
+  out.width = png->getWidth();
+  out.height = png->getHeight();
+
+  png->close();
+  delete png;
+  return true;
+}
+
+bool PngToFramebufferConverter::decodeToFramebuffer(const std::string& imagePath, GfxRenderer& renderer,
+                                                    const RenderConfig& config) {
+  LOG_DBG("PNG", "Decoding PNG: %s", imagePath.c_str());
+
+  size_t freeHeap = ESP.getFreeHeap();
+  if (freeHeap < MIN_FREE_HEAP_FOR_PNG) {
+    LOG_ERR("PNG", "Not enough heap for PNG decoder (%u free, need %u)", freeHeap, MIN_FREE_HEAP_FOR_PNG);
+    return false;
+  }
+
+  // Heap-allocate PNG decoder (~42 KB) - freed at end of function
+  PNG* png = new (std::nothrow) PNG();
+  if (!png) {
+    LOG_ERR("PNG", "Failed to allocate PNG decoder");
+    return false;
+  }
+
+  PngContext ctx;
+  ctx.renderer = &renderer;
+  ctx.config = &config;
+  ctx.screenWidth = renderer.getScreenWidth();
+  ctx.screenHeight = renderer.getScreenHeight();
+
+  int rc = png->open(imagePath.c_str(), pngOpenWithHandle, pngCloseWithHandle, pngReadWithHandle, pngSeekWithHandle,
+                     pngDrawCallback);
+  if (rc != PNG_SUCCESS) {
+    LOG_ERR("PNG", "Failed to open PNG: %d", rc);
+    delete png;
+    return false;
+  }
+
+  if (!validateImageDimensions(png->getWidth(), png->getHeight(), "PNG")) {
+    png->close();
+    delete png;
+    return false;
+  }
+
+  // Calculate output dimensions
+  ctx.srcWidth = png->getWidth();
+  ctx.srcHeight = png->getHeight();
+
+  if (config.useExactDimensions && config.maxWidth > 0 && config.maxHeight > 0) {
+    // Use exact dimensions as specified (avoids rounding mismatches with pre-calculated sizes)
+    ctx.dstWidth = config.maxWidth;
+    ctx.dstHeight = config.maxHeight;
+    ctx.scale = (float)ctx.dstWidth / ctx.srcWidth;
+  } else {
+    // Calculate scale factor to fit within maxWidth/maxHeight
+    float scaleX = (float)config.maxWidth / ctx.srcWidth;
+    float scaleY = (float)config.maxHeight / ctx.srcHeight;
+    ctx.scale = (scaleX < scaleY) ? scaleX : scaleY;
+    if (ctx.scale > 1.0f) ctx.scale = 1.0f;  // Don't upscale
+
+    ctx.dstWidth = (int)(ctx.srcWidth * ctx.scale);
+    ctx.dstHeight = (int)(ctx.srcHeight * ctx.scale);
+  }
+  ctx.lastDstY = -1;  // Reset row tracking
+
+  LOG_DBG("PNG", "PNG %dx%d -> %dx%d (scale %.2f), bpp: %d", ctx.srcWidth, ctx.srcHeight, ctx.dstWidth, ctx.dstHeight,
+          ctx.scale, png->getBpp());
+
+  const int pixelType = png->getPixelType();
+  const int requiredInternal = requiredPngInternalBufferBytes(ctx.srcWidth, pixelType);
+  if (requiredInternal > PNG_MAX_BUFFERED_PIXELS) {
+    LOG_ERR("PNG",
+            "PNG row buffer too small: need %d bytes for width=%d type=%d, configured PNG_MAX_BUFFERED_PIXELS=%d",
+            requiredInternal, ctx.srcWidth, pixelType, PNG_MAX_BUFFERED_PIXELS);
+    LOG_ERR("PNG", "Aborting decode to avoid PNGdec internal buffer overflow");
+    png->close();
+    delete png;
+    return false;
+  }
+
+  if (png->getBpp() != 8) {
+    warnUnsupportedFeature("bit depth (" + std::to_string(png->getBpp()) + "bpp)", imagePath);
+  }
+
+  // Allocate grayscale line buffer on demand (~3.2 KB) - freed after decode
+  const size_t grayBufSize = PNG_MAX_BUFFERED_PIXELS / 2;
+  ctx.grayLineBuffer = static_cast<uint8_t*>(malloc(grayBufSize));
+  if (!ctx.grayLineBuffer) {
+    LOG_ERR("PNG", "Failed to allocate gray line buffer");
+    png->close();
+    delete png;
+    return false;
+  }
+
+  // Allocate cache buffer using SCALED dimensions
+  ctx.caching = !config.cachePath.empty();
+  if (ctx.caching) {
+    if (!ctx.cache.allocate(ctx.dstWidth, ctx.dstHeight, config.x, config.y)) {
+      LOG_ERR("PNG", "Failed to allocate cache buffer, continuing without caching");
+      ctx.caching = false;
+    }
+  }
+
+  unsigned long decodeStart = millis();
+  rc = png->decode(&ctx, 0);
+  unsigned long decodeTime = millis() - decodeStart;
+
+  free(ctx.grayLineBuffer);
+  ctx.grayLineBuffer = nullptr;
+
+  if (rc != PNG_SUCCESS) {
+    LOG_ERR("PNG", "Decode failed: %d", rc);
+    png->close();
+    delete png;
+    return false;
+  }
+
+  png->close();
+  delete png;
+  LOG_DBG("PNG", "PNG decoding complete - render time: %lu ms", decodeTime);
+
+  // Write cache file if caching was enabled and buffer was allocated
+  if (ctx.caching) {
+    ctx.cache.writeToFile(config.cachePath);
+  }
+
+  return true;
+}
+
+bool PngToFramebufferConverter::supportsFormat(const std::string& extension) {
+  std::string ext = extension;
+  for (auto& c : ext) {
+    c = tolower(c);
+  }
+  return (ext == ".png");
+}

lib/Epub/Epub/converters/PngToFramebufferConverter.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "ImageToFramebufferDecoder.h"
+
+class PngToFramebufferConverter final : public ImageToFramebufferDecoder {
+ public:
+  static bool getDimensionsStatic(const std::string& imagePath, ImageDimensions& out);
+
+  bool decodeToFramebuffer(const std::string& imagePath, GfxRenderer& renderer, const RenderConfig& config) override;
+
+  bool getDimensions(const std::string& imagePath, ImageDimensions& dims) const override {
+    return getDimensionsStatic(imagePath, dims);
+  }
+
+  static bool supportsFormat(const std::string& extension);
+  const char* getFormatName() const override { return "PNG"; }
+};

lib/Epub/Epub/css/CssParser.cpp

@@ -1,144 +1,57 @@
 #include "CssParser.h"
 
+#include <Arduino.h>
 #include <Logging.h>
 
 #include <algorithm>
+#include <array>
 #include <cctype>
+#include <string_view>
 
 namespace {
 
+// Stack-allocated string buffer to avoid heap reallocations during parsing
+// Provides string-like interface with fixed capacity
+struct StackBuffer {
+  static constexpr size_t CAPACITY = 1024;
+  char data[CAPACITY];
+  size_t len = 0;
+
+  void push_back(char c) {
+    if (len < CAPACITY - 1) {
+      data[len++] = c;
+    }
+  }
+
+  void clear() { len = 0; }
+  bool empty() const { return len == 0; }
+  size_t size() const { return len; }
+
+  // Get string view of current content (zero-copy)
+  std::string_view view() const { return std::string_view(data, len); }
+
+  // Convert to string for passing to functions (single allocation)
+  std::string str() const { return std::string(data, len); }
+};
+
 // Buffer size for reading CSS files
 constexpr size_t READ_BUFFER_SIZE = 512;
 
-// Maximum CSS file size we'll process (prevent memory issues)
-constexpr size_t MAX_CSS_SIZE = 64 * 1024;
+// Maximum number of CSS rules to store in the selector map
+// Prevents unbounded memory growth from pathological CSS files
+constexpr size_t MAX_RULES = 1500;
+
+// Minimum free heap required to apply CSS during rendering
+// If below this threshold, we skip CSS to avoid display artifacts.
+constexpr size_t MIN_FREE_HEAP_FOR_CSS = 48 * 1024;
+
+// Maximum length for a single selector string
+// Prevents parsing of extremely long or malformed selectors
+constexpr size_t MAX_SELECTOR_LENGTH = 256;
 
 // Check if character is CSS whitespace
 bool isCssWhitespace(const char c) { return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '\f'; }
 
-// Read entire file into string (with size limit)
-std::string readFileContent(FsFile& file) {
-  std::string content;
-  content.reserve(std::min(static_cast<size_t>(file.size()), MAX_CSS_SIZE));
-
-  char buffer[READ_BUFFER_SIZE];
-  while (file.available() && content.size() < MAX_CSS_SIZE) {
-    const int bytesRead = file.read(buffer, sizeof(buffer));
-    if (bytesRead <= 0) break;
-    content.append(buffer, bytesRead);
-  }
-  return content;
-}
-
-// Remove CSS comments (/* ... */) from content
-std::string stripComments(const std::string& css) {
-  std::string result;
-  result.reserve(css.size());
-
-  size_t pos = 0;
-  while (pos < css.size()) {
-    // Look for start of comment
-    if (pos + 1 < css.size() && css[pos] == '/' && css[pos + 1] == '*') {
-      // Find end of comment
-      const size_t endPos = css.find("*/", pos + 2);
-      if (endPos == std::string::npos) {
-        // Unterminated comment - skip rest of file
-        break;
-      }
-      pos = endPos + 2;
-    } else {
-      result.push_back(css[pos]);
-      ++pos;
-    }
-  }
-  return result;
-}
-
-// Skip @-rules (like @media, @import, @font-face)
-// Returns position after the @-rule
-size_t skipAtRule(const std::string& css, const size_t start) {
-  // Find the end - either semicolon (simple @-rule) or matching brace
-  size_t pos = start + 1;  // Skip the '@'
-
-  // Skip identifier
-  while (pos < css.size() && (std::isalnum(css[pos]) || css[pos] == '-')) {
-    ++pos;
-  }
-
-  // Look for { or ;
-  int braceDepth = 0;
-  while (pos < css.size()) {
-    const char c = css[pos];
-    if (c == '{') {
-      ++braceDepth;
-    } else if (c == '}') {
-      --braceDepth;
-      if (braceDepth == 0) {
-        return pos + 1;
-      }
-    } else if (c == ';' && braceDepth == 0) {
-      return pos + 1;
-    }
-    ++pos;
-  }
-  return css.size();
-}
-
-// Extract next rule from CSS content
-// Returns true if a rule was found, with selector and body filled
-bool extractNextRule(const std::string& css, size_t& pos, std::string& selector, std::string& body) {
-  selector.clear();
-  body.clear();
-
-  // Skip whitespace and @-rules until we find a regular rule
-  while (pos < css.size()) {
-    // Skip whitespace
-    while (pos < css.size() && isCssWhitespace(css[pos])) {
-      ++pos;
-    }
-
-    if (pos >= css.size()) return false;
-
-    // Handle @-rules iteratively (avoids recursion/stack overflow)
-    if (css[pos] == '@') {
-      pos = skipAtRule(css, pos);
-      continue;  // Try again after skipping the @-rule
-    }
-
-    break;  // Found start of a regular rule
-  }
-
-  if (pos >= css.size()) return false;
-
-  // Find opening brace
-  const size_t bracePos = css.find('{', pos);
-  if (bracePos == std::string::npos) return false;
-
-  // Extract selector (everything before the brace)
-  selector = css.substr(pos, bracePos - pos);
-
-  // Find matching closing brace
-  int depth = 1;
-  const size_t bodyStart = bracePos + 1;
-  size_t bodyEnd = bodyStart;
-
-  while (bodyEnd < css.size() && depth > 0) {
-    if (css[bodyEnd] == '{')
-      ++depth;
-    else if (css[bodyEnd] == '}')
-      --depth;
-    ++bodyEnd;
-  }
-
-  // Extract body (between braces)
-  if (bodyEnd > bodyStart) {
-    body = css.substr(bodyStart, bodyEnd - bodyStart - 1);
-  }
-
-  pos = bodyEnd;
-  return true;
-}
-
 }  // anonymous namespace
 
 // String utilities implementation
@@ -161,12 +74,34 @@ std::string CssParser::normalized(const std::string& s) {
   }
 
   // Remove trailing space
-  if (!result.empty() && result.back() == ' ') {
+  while (!result.empty() && (result.back() == ' ' || result.back() == '\n')) {
     result.pop_back();
   }
   return result;
 }
 
+void CssParser::normalizedInto(const std::string& s, std::string& out) {
+  out.clear();
+  out.reserve(s.size());
+
+  bool inSpace = true;  // Start true to skip leading space
+  for (const char c : s) {
+    if (isCssWhitespace(c)) {
+      if (!inSpace) {
+        out.push_back(' ');
+        inSpace = true;
+      }
+    } else {
+      out.push_back(static_cast<char>(std::tolower(static_cast<unsigned char>(c))));
+      inSpace = false;
+    }
+  }
+
+  if (!out.empty() && out.back() == ' ') {
+    out.pop_back();
+  }
+}
+
 std::vector<std::string> CssParser::splitOnChar(const std::string& s, const char delimiter) {
   std::vector<std::string> parts;
   size_t start = 0;
@@ -254,10 +189,18 @@ CssTextDecoration CssParser::interpretDecoration(const std::string& val) {
 }
 
 CssLength CssParser::interpretLength(const std::string& val) {
+  CssLength result;
+  tryInterpretLength(val, result);
+  return result;
+}
+
+bool CssParser::tryInterpretLength(const std::string& val, CssLength& out) {
   const std::string v = normalized(val);
-  if (v.empty()) return CssLength{};
+  if (v.empty()) {
+    out = CssLength{};
+    return false;
+  }
 
-  // Find where the number ends
   size_t unitStart = v.size();
   for (size_t i = 0; i < v.size(); ++i) {
     const char c = v[i];
@@ -270,12 +213,13 @@ CssLength CssParser::interpretLength(const std::string& val) {
   const std::string numPart = v.substr(0, unitStart);
   const std::string unitPart = v.substr(unitStart);
 
-  // Parse numeric value
   char* endPtr = nullptr;
   const float numericValue = std::strtof(numPart.c_str(), &endPtr);
-  if (endPtr == numPart.c_str()) return CssLength{};  // No number parsed
+  if (endPtr == numPart.c_str()) {
+    out = CssLength{};
+    return false;  // No number parsed (e.g. auto, inherit, initial)
+  }
 
-  // Determine unit type (preserve for deferred resolution)
   auto unit = CssUnit::Pixels;
   if (unitPart == "em") {
     unit = CssUnit::Em;
@@ -286,133 +230,112 @@ CssLength CssParser::interpretLength(const std::string& val) {
   } else if (unitPart == "%") {
     unit = CssUnit::Percent;
   }
-  // px and unitless default to Pixels
 
-  return CssLength{numericValue, unit};
-}
-
-int8_t CssParser::interpretSpacing(const std::string& val) {
-  const std::string v = normalized(val);
-  if (v.empty()) return 0;
-
-  // For spacing, we convert to "lines" (discrete units for e-ink)
-  // 1em ≈ 1 line, percentages based on ~30 lines per page
-
-  float multiplier = 0.0f;
-  size_t unitStart = v.size();
-
-  for (size_t i = 0; i < v.size(); ++i) {
-    const char c = v[i];
-    if (!std::isdigit(c) && c != '.' && c != '-' && c != '+') {
-      unitStart = i;
-      break;
-    }
-  }
-
-  const std::string numPart = v.substr(0, unitStart);
-  const std::string unitPart = v.substr(unitStart);
-
-  if (unitPart == "em" || unitPart == "rem") {
-    multiplier = 1.0f;  // 1em = 1 line
-  } else if (unitPart == "%") {
-    multiplier = 0.3f;  // ~30 lines per page, so 10% = 3 lines
-  } else {
-    return 0;  // Unsupported unit for spacing
-  }
-
-  char* endPtr = nullptr;
-  const float numericValue = std::strtof(numPart.c_str(), &endPtr);
-
-  if (endPtr == numPart.c_str()) return 0;
-
-  int lines = static_cast<int>(numericValue * multiplier);
-
-  // Clamp to reasonable range (0-2 lines)
-  if (lines < 0) lines = 0;
-  if (lines > 2) lines = 2;
-
-  return static_cast<int8_t>(lines);
+  out = CssLength{numericValue, unit};
+  return true;
 }
 
 // Declaration parsing
 
+void CssParser::parseDeclarationIntoStyle(const std::string& decl, CssStyle& style, std::string& propNameBuf,
+                                          std::string& propValueBuf) {
+  const size_t colonPos = decl.find(':');
+  if (colonPos == std::string::npos || colonPos == 0) return;
+
+  normalizedInto(decl.substr(0, colonPos), propNameBuf);
+  normalizedInto(decl.substr(colonPos + 1), propValueBuf);
+
+  if (propNameBuf.empty() || propValueBuf.empty()) return;
+
+  if (propNameBuf == "text-align") {
+    style.textAlign = interpretAlignment(propValueBuf);
+    style.defined.textAlign = 1;
+  } else if (propNameBuf == "font-style") {
+    style.fontStyle = interpretFontStyle(propValueBuf);
+    style.defined.fontStyle = 1;
+  } else if (propNameBuf == "font-weight") {
+    style.fontWeight = interpretFontWeight(propValueBuf);
+    style.defined.fontWeight = 1;
+  } else if (propNameBuf == "text-decoration" || propNameBuf == "text-decoration-line") {
+    style.textDecoration = interpretDecoration(propValueBuf);
+    style.defined.textDecoration = 1;
+  } else if (propNameBuf == "text-indent") {
+    style.textIndent = interpretLength(propValueBuf);
+    style.defined.textIndent = 1;
+  } else if (propNameBuf == "margin-top") {
+    style.marginTop = interpretLength(propValueBuf);
+    style.defined.marginTop = 1;
+  } else if (propNameBuf == "margin-bottom") {
+    style.marginBottom = interpretLength(propValueBuf);
+    style.defined.marginBottom = 1;
+  } else if (propNameBuf == "margin-left") {
+    style.marginLeft = interpretLength(propValueBuf);
+    style.defined.marginLeft = 1;
+  } else if (propNameBuf == "margin-right") {
+    style.marginRight = interpretLength(propValueBuf);
+    style.defined.marginRight = 1;
+  } else if (propNameBuf == "margin") {
+    const auto values = splitWhitespace(propValueBuf);
+    if (!values.empty()) {
+      style.marginTop = interpretLength(values[0]);
+      style.marginRight = values.size() >= 2 ? interpretLength(values[1]) : style.marginTop;
+      style.marginBottom = values.size() >= 3 ? interpretLength(values[2]) : style.marginTop;
+      style.marginLeft = values.size() >= 4 ? interpretLength(values[3]) : style.marginRight;
+      style.defined.marginTop = style.defined.marginRight = style.defined.marginBottom = style.defined.marginLeft = 1;
+    }
+  } else if (propNameBuf == "padding-top") {
+    style.paddingTop = interpretLength(propValueBuf);
+    style.defined.paddingTop = 1;
+  } else if (propNameBuf == "padding-bottom") {
+    style.paddingBottom = interpretLength(propValueBuf);
+    style.defined.paddingBottom = 1;
+  } else if (propNameBuf == "padding-left") {
+    style.paddingLeft = interpretLength(propValueBuf);
+    style.defined.paddingLeft = 1;
+  } else if (propNameBuf == "padding-right") {
+    style.paddingRight = interpretLength(propValueBuf);
+    style.defined.paddingRight = 1;
+  } else if (propNameBuf == "padding") {
+    const auto values = splitWhitespace(propValueBuf);
+    if (!values.empty()) {
+      style.paddingTop = interpretLength(values[0]);
+      style.paddingRight = values.size() >= 2 ? interpretLength(values[1]) : style.paddingTop;
+      style.paddingBottom = values.size() >= 3 ? interpretLength(values[2]) : style.paddingTop;
+      style.paddingLeft = values.size() >= 4 ? interpretLength(values[3]) : style.paddingRight;
+      style.defined.paddingTop = style.defined.paddingRight = style.defined.paddingBottom = style.defined.paddingLeft =
+          1;
+    }
+  } else if (propNameBuf == "height") {
+    CssLength len;
+    if (tryInterpretLength(propValueBuf, len)) {
+      style.imageHeight = len;
+      style.defined.imageHeight = 1;
+    }
+  } else if (propNameBuf == "width") {
+    CssLength len;
+    if (tryInterpretLength(propValueBuf, len)) {
+      style.imageWidth = len;
+      style.defined.imageWidth = 1;
+    }
+  }
+}
+
 CssStyle CssParser::parseDeclarations(const std::string& declBlock) {
   CssStyle style;
+  std::string propNameBuf;
+  std::string propValueBuf;
 
-  // Split declarations by semicolon
-  const auto declarations = splitOnChar(declBlock, ';');
-
-  for (const auto& decl : declarations) {
-    // Find colon separator
-    const size_t colonPos = decl.find(':');
-    if (colonPos == std::string::npos || colonPos == 0) continue;
-
-    std::string propName = normalized(decl.substr(0, colonPos));
-    std::string propValue = normalized(decl.substr(colonPos + 1));
-
-    if (propName.empty() || propValue.empty()) continue;
-
-    // Match property and set value
-    if (propName == "text-align") {
-      style.textAlign = interpretAlignment(propValue);
-      style.defined.textAlign = 1;
-    } else if (propName == "font-style") {
-      style.fontStyle = interpretFontStyle(propValue);
-      style.defined.fontStyle = 1;
-    } else if (propName == "font-weight") {
-      style.fontWeight = interpretFontWeight(propValue);
-      style.defined.fontWeight = 1;
-    } else if (propName == "text-decoration" || propName == "text-decoration-line") {
-      style.textDecoration = interpretDecoration(propValue);
-      style.defined.textDecoration = 1;
-    } else if (propName == "text-indent") {
-      style.textIndent = interpretLength(propValue);
-      style.defined.textIndent = 1;
-    } else if (propName == "margin-top") {
-      style.marginTop = interpretLength(propValue);
-      style.defined.marginTop = 1;
-    } else if (propName == "margin-bottom") {
-      style.marginBottom = interpretLength(propValue);
-      style.defined.marginBottom = 1;
-    } else if (propName == "margin-left") {
-      style.marginLeft = interpretLength(propValue);
-      style.defined.marginLeft = 1;
-    } else if (propName == "margin-right") {
-      style.marginRight = interpretLength(propValue);
-      style.defined.marginRight = 1;
-    } else if (propName == "margin") {
-      // Shorthand: 1-4 values for top, right, bottom, left
-      const auto values = splitWhitespace(propValue);
-      if (!values.empty()) {
-        style.marginTop = interpretLength(values[0]);
-        style.marginRight = values.size() >= 2 ? interpretLength(values[1]) : style.marginTop;
-        style.marginBottom = values.size() >= 3 ? interpretLength(values[2]) : style.marginTop;
-        style.marginLeft = values.size() >= 4 ? interpretLength(values[3]) : style.marginRight;
-        style.defined.marginTop = style.defined.marginRight = style.defined.marginBottom = style.defined.marginLeft = 1;
-      }
-    } else if (propName == "padding-top") {
-      style.paddingTop = interpretLength(propValue);
-      style.defined.paddingTop = 1;
-    } else if (propName == "padding-bottom") {
-      style.paddingBottom = interpretLength(propValue);
-      style.defined.paddingBottom = 1;
-    } else if (propName == "padding-left") {
-      style.paddingLeft = interpretLength(propValue);
-      style.defined.paddingLeft = 1;
-    } else if (propName == "padding-right") {
-      style.paddingRight = interpretLength(propValue);
-      style.defined.paddingRight = 1;
-    } else if (propName == "padding") {
-      // Shorthand: 1-4 values for top, right, bottom, left
-      const auto values = splitWhitespace(propValue);
-      if (!values.empty()) {
-        style.paddingTop = interpretLength(values[0]);
-        style.paddingRight = values.size() >= 2 ? interpretLength(values[1]) : style.paddingTop;
-        style.paddingBottom = values.size() >= 3 ? interpretLength(values[2]) : style.paddingTop;
-        style.paddingLeft = values.size() >= 4 ? interpretLength(values[3]) : style.paddingRight;
-        style.defined.paddingTop = style.defined.paddingRight = style.defined.paddingBottom =
-            style.defined.paddingLeft = 1;
+  size_t start = 0;
+  for (size_t i = 0; i <= declBlock.size(); ++i) {
+    if (i == declBlock.size() || declBlock[i] == ';') {
+      if (i > start) {
+        const size_t len = i - start;
+        std::string decl = declBlock.substr(start, len);
+        if (!decl.empty()) {
+          parseDeclarationIntoStyle(decl, style, propNameBuf, propValueBuf);
+        }
       }
+      start = i + 1;
     }
   }
 
@@ -421,20 +344,83 @@ CssStyle CssParser::parseDeclarations(const std::string& declBlock) {
 
 // Rule processing
 
-void CssParser::processRuleBlock(const std::string& selectorGroup, const std::string& declarations) {
-  const CssStyle style = parseDeclarations(declarations);
-
-  // Only store if any properties were set
-  if (!style.defined.anySet()) return;
+void CssParser::processRuleBlockWithStyle(const std::string& selectorGroup, const CssStyle& style) {
+  // Check if we've reached the rule limit before processing
+  if (rulesBySelector_.size() >= MAX_RULES) {
+    LOG_DBG("CSS", "Reached max rules limit (%zu), stopping CSS parsing", MAX_RULES);
+    return;
+  }
 
   // Handle comma-separated selectors
   const auto selectors = splitOnChar(selectorGroup, ',');
 
   for (const auto& sel : selectors) {
+    // Validate selector length before processing
+    if (sel.size() > MAX_SELECTOR_LENGTH) {
+      LOG_DBG("CSS", "Selector too long (%zu > %zu), skipping", sel.size(), MAX_SELECTOR_LENGTH);
+      continue;
+    }
+
     // Normalize the selector
     std::string key = normalized(sel);
     if (key.empty()) continue;
 
+    // TODO: Consider adding support for sibling css selectors in the future
+    // Ensure no + in selector as we don't support adjacent CSS selectors for now
+    if (key.find('+') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for direct nested css selectors in the future
+    // Ensure no > in selector as we don't support nested CSS selectors for now
+    if (key.find('>') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for attribute css selectors in the future
+    // Ensure no [ in selector as we don't support attribute CSS selectors for now
+    if (key.find('[') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for pseudo selectors in the future
+    // Ensure no : in selector as we don't support pseudo CSS selectors for now
+    if (key.find(':') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for ID css selectors in the future
+    // Ensure no # in selector as we don't support ID CSS selectors for now
+    if (key.find('#') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for general sibling combinator selectors in the future
+    // Ensure no ~ in selector as we don't support general sibling combinator CSS selectors for now
+    if (key.find('~') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Consider adding support for wildcard css selectors in the future
+    // Ensure no * in selector as we don't support wildcard CSS selectors for now
+    if (key.find('*') != std::string_view::npos) {
+      continue;
+    }
+
+    // TODO: Add support for more complex selectors in the future
+    // At the moment, we only ever check for `tag`, `tag.class1` or `.class1`
+    // If the selector has whitespace in it, then it's either a CSS selector for a descendant element (e.g. `tag1 tag2`)
+    // or some other slightly more advanced CSS selector which we don't support yet
+    if (key.find(' ') != std::string_view::npos) {
+      continue;
+    }
+
+    // Skip if this would exceed the rule limit
+    if (rulesBySelector_.size() >= MAX_RULES) {
+      LOG_DBG("CSS", "Reached max rules limit, stopping selector processing");
+      return;
+    }
+
     // Store or merge with existing
     auto it = rulesBySelector_.find(key);
     if (it != rulesBySelector_.end()) {
@@ -453,30 +439,158 @@ bool CssParser::loadFromStream(FsFile& source) {
     return false;
   }
 
-  // Read file content
-  const std::string content = readFileContent(source);
-  if (content.empty()) {
-    return true;  // Empty file is valid
+  size_t totalRead = 0;
+
+  // Use stack-allocated buffers for parsing to avoid heap reallocations
+  StackBuffer selector;
+  StackBuffer declBuffer;
+  // Keep these as std::string since they're passed by reference to parseDeclarationIntoStyle
+  std::string propNameBuf;
+  std::string propValueBuf;
+
+  bool inComment = false;
+  bool maybeSlash = false;
+  bool prevStar = false;
+
+  bool inAtRule = false;
+  int atDepth = 0;
+
+  int bodyDepth = 0;
+  bool skippingRule = false;
+  CssStyle currentStyle;
+
+  auto handleChar = [&](const char c) {
+    if (inAtRule) {
+      if (c == '{') {
+        ++atDepth;
+      } else if (c == '}') {
+        if (atDepth > 0) --atDepth;
+        if (atDepth == 0) inAtRule = false;
+      } else if (c == ';' && atDepth == 0) {
+        inAtRule = false;
+      }
+      return;
+    }
+
+    if (bodyDepth == 0) {
+      if (selector.empty() && isCssWhitespace(c)) {
+        return;
+      }
+      if (c == '@' && selector.empty()) {
+        inAtRule = true;
+        atDepth = 0;
+        return;
+      }
+      if (c == '{') {
+        bodyDepth = 1;
+        currentStyle = CssStyle{};
+        declBuffer.clear();
+        if (selector.size() > MAX_SELECTOR_LENGTH * 4) {
+          skippingRule = true;
+        }
+        return;
+      }
+      selector.push_back(c);
+      return;
+    }
+
+    // bodyDepth > 0
+    if (c == '{') {
+      ++bodyDepth;
+      return;
+    }
+    if (c == '}') {
+      --bodyDepth;
+      if (bodyDepth == 0) {
+        if (!skippingRule && !declBuffer.empty()) {
+          parseDeclarationIntoStyle(declBuffer.str(), currentStyle, propNameBuf, propValueBuf);
+        }
+        if (!skippingRule) {
+          processRuleBlockWithStyle(selector.str(), currentStyle);
+        }
+        selector.clear();
+        declBuffer.clear();
+        skippingRule = false;
+        return;
+      }
+      return;
+    }
+    if (bodyDepth > 1) {
+      return;
+    }
+    if (!skippingRule) {
+      if (c == ';') {
+        if (!declBuffer.empty()) {
+          parseDeclarationIntoStyle(declBuffer.str(), currentStyle, propNameBuf, propValueBuf);
+          declBuffer.clear();
+        }
+      } else {
+        declBuffer.push_back(c);
+      }
+    }
+  };
+
+  char buffer[READ_BUFFER_SIZE];
+  while (source.available()) {
+    int bytesRead = source.read(buffer, sizeof(buffer));
+    if (bytesRead <= 0) break;
+
+    totalRead += static_cast<size_t>(bytesRead);
+
+    for (int i = 0; i < bytesRead; ++i) {
+      const char c = buffer[i];
+
+      if (inComment) {
+        if (prevStar && c == '/') {
+          inComment = false;
+          prevStar = false;
+          continue;
+        }
+        prevStar = c == '*';
+        continue;
+      }
+
+      if (maybeSlash) {
+        if (c == '*') {
+          inComment = true;
+          maybeSlash = false;
+          prevStar = false;
+          continue;
+        }
+        handleChar('/');
+        maybeSlash = false;
+        // fall through to process current char
+      }
+
+      if (c == '/') {
+        maybeSlash = true;
+        continue;
+      }
+
+      handleChar(c);
+    }
   }
 
-  // Remove comments
-  const std::string cleaned = stripComments(content);
-
-  // Parse rules
-  size_t pos = 0;
-  std::string selector, body;
-
-  while (extractNextRule(cleaned, pos, selector, body)) {
-    processRuleBlock(selector, body);
+  if (maybeSlash) {
+    handleChar('/');
   }
 
-  LOG_DBG("CSS", "Parsed %zu rules", rulesBySelector_.size());
+  LOG_DBG("CSS", "Parsed %zu rules from %zu bytes", rulesBySelector_.size(), totalRead);
   return true;
 }
 
 // Style resolution
 
 CssStyle CssParser::resolveStyle(const std::string& tagName, const std::string& classAttr) const {
+  static bool lowHeapWarningLogged = false;
+  if (ESP.getFreeHeap() < MIN_FREE_HEAP_FOR_CSS) {
+    if (!lowHeapWarningLogged) {
+      lowHeapWarningLogged = true;
+      LOG_DBG("CSS", "Warning: low heap (%u bytes) below MIN_FREE_HEAP_FOR_CSS (%u), returning empty style",
+              ESP.getFreeHeap(), static_cast<unsigned>(MIN_FREE_HEAP_FOR_CSS));
+    }
+    return CssStyle{};
+  }
   CssStyle result;
   const std::string tag = normalized(tagName);
 
@@ -486,6 +600,7 @@ CssStyle CssParser::resolveStyle(const std::string& tagName, const std::string&
     result.applyOver(tagIt->second);
   }
 
+  // TODO: Support combinations of classes (e.g. style on .class1.class2)
   // 2. Apply class styles (medium priority)
   if (!classAttr.empty()) {
     const auto classes = splitWhitespace(classAttr);
@@ -499,6 +614,7 @@ CssStyle CssParser::resolveStyle(const std::string& tagName, const std::string&
       }
     }
 
+    // TODO: Support combinations of classes (e.g. style on p.class1.class2)
     // 3. Apply element.class styles (higher priority)
     for (const auto& cls : classes) {
       std::string combinedKey = tag + "." + normalized(cls);
@@ -519,16 +635,27 @@ CssStyle CssParser::parseInlineStyle(const std::string& styleValue) { return par
 
 // Cache serialization
 
-// Cache format version - increment when format changes
-constexpr uint8_t CSS_CACHE_VERSION = 2;
+// Cache file name (version is CssParser::CSS_CACHE_VERSION)
+constexpr char rulesCache[] = "/css_rules.cache";
 
-bool CssParser::saveToCache(FsFile& file) const {
-  if (!file) {
+bool CssParser::hasCache() const { return Storage.exists((cachePath + rulesCache).c_str()); }
+
+void CssParser::deleteCache() const {
+  if (hasCache()) Storage.remove((cachePath + rulesCache).c_str());
+}
+
+bool CssParser::saveToCache() const {
+  if (cachePath.empty()) {
+    return false;
+  }
+
+  FsFile file;
+  if (!Storage.openFileForWrite("CSS", cachePath + rulesCache, file)) {
     return false;
   }
 
   // Write version
-  file.write(CSS_CACHE_VERSION);
+  file.write(CssParser::CSS_CACHE_VERSION);
 
   // Write rule count
   const auto ruleCount = static_cast<uint16_t>(rulesBySelector_.size());
@@ -563,6 +690,8 @@ bool CssParser::saveToCache(FsFile& file) const {
     writeLength(style.paddingBottom);
     writeLength(style.paddingLeft);
     writeLength(style.paddingRight);
+    writeLength(style.imageHeight);
+    writeLength(style.imageWidth);
 
     // Write defined flags as uint16_t
     uint16_t definedBits = 0;
@@ -579,15 +708,23 @@ bool CssParser::saveToCache(FsFile& file) const {
     if (style.defined.paddingBottom) definedBits |= 1 << 10;
     if (style.defined.paddingLeft) definedBits |= 1 << 11;
     if (style.defined.paddingRight) definedBits |= 1 << 12;
+    if (style.defined.imageHeight) definedBits |= 1 << 13;
+    if (style.defined.imageWidth) definedBits |= 1 << 14;
     file.write(reinterpret_cast<const uint8_t*>(&definedBits), sizeof(definedBits));
   }
 
   LOG_DBG("CSS", "Saved %u rules to cache", ruleCount);
+  file.close();
   return true;
 }
 
-bool CssParser::loadFromCache(FsFile& file) {
-  if (!file) {
+bool CssParser::loadFromCache() {
+  if (cachePath.empty()) {
+    return false;
+  }
+
+  FsFile file;
+  if (!Storage.openFileForRead("CSS", cachePath + rulesCache, file)) {
     return false;
   }
 
@@ -596,14 +733,18 @@ bool CssParser::loadFromCache(FsFile& file) {
 
   // Read and verify version
   uint8_t version = 0;
-  if (file.read(&version, 1) != 1 || version != CSS_CACHE_VERSION) {
-    LOG_DBG("CSS", "Cache version mismatch (got %u, expected %u)", version, CSS_CACHE_VERSION);
+  if (file.read(&version, 1) != 1 || version != CssParser::CSS_CACHE_VERSION) {
+    LOG_DBG("CSS", "Cache version mismatch (got %u, expected %u), removing stale cache for rebuild", version,
+            CssParser::CSS_CACHE_VERSION);
+    file.close();
+    Storage.remove((cachePath + rulesCache).c_str());
     return false;
   }
 
   // Read rule count
   uint16_t ruleCount = 0;
   if (file.read(&ruleCount, sizeof(ruleCount)) != sizeof(ruleCount)) {
+    file.close();
     return false;
   }
 
@@ -613,6 +754,7 @@ bool CssParser::loadFromCache(FsFile& file) {
     uint16_t selectorLen = 0;
     if (file.read(&selectorLen, sizeof(selectorLen)) != sizeof(selectorLen)) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
 
@@ -620,6 +762,7 @@ bool CssParser::loadFromCache(FsFile& file) {
     selector.resize(selectorLen);
     if (file.read(&selector[0], selectorLen) != selectorLen) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
 
@@ -629,24 +772,28 @@ bool CssParser::loadFromCache(FsFile& file) {
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
     style.textAlign = static_cast<CssTextAlign>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
     style.fontStyle = static_cast<CssFontStyle>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
     style.fontWeight = static_cast<CssFontWeight>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
     style.textDecoration = static_cast<CssTextDecoration>(enumVal);
@@ -666,8 +813,10 @@ bool CssParser::loadFromCache(FsFile& file) {
 
     if (!readLength(style.textIndent) || !readLength(style.marginTop) || !readLength(style.marginBottom) ||
         !readLength(style.marginLeft) || !readLength(style.marginRight) || !readLength(style.paddingTop) ||
-        !readLength(style.paddingBottom) || !readLength(style.paddingLeft) || !readLength(style.paddingRight)) {
+        !readLength(style.paddingBottom) || !readLength(style.paddingLeft) || !readLength(style.paddingRight) ||
+        !readLength(style.imageHeight) || !readLength(style.imageWidth)) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
 
@@ -675,6 +824,7 @@ bool CssParser::loadFromCache(FsFile& file) {
     uint16_t definedBits = 0;
     if (file.read(&definedBits, sizeof(definedBits)) != sizeof(definedBits)) {
       rulesBySelector_.clear();
+      file.close();
       return false;
     }
     style.defined.textAlign = (definedBits & 1 << 0) != 0;
@@ -690,10 +840,13 @@ bool CssParser::loadFromCache(FsFile& file) {
     style.defined.paddingBottom = (definedBits & 1 << 10) != 0;
     style.defined.paddingLeft = (definedBits & 1 << 11) != 0;
     style.defined.paddingRight = (definedBits & 1 << 12) != 0;
+    style.defined.imageHeight = (definedBits & 1 << 13) != 0;
+    style.defined.imageWidth = (definedBits & 1 << 14) != 0;
 
     rulesBySelector_[selector] = style;
   }
 
   LOG_DBG("CSS", "Loaded %u rules from cache", ruleCount);
+  file.close();
   return true;
 }

lib/Epub/Epub/css/CssParser.h

@@ -4,6 +4,7 @@
 
 #include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include "CssStyle.h"
@@ -29,7 +30,10 @@
  */
 class CssParser {
  public:
-  CssParser() = default;
+  // Bump when CSS cache format or rules change; section caches are invalidated when this changes
+  static constexpr uint8_t CSS_CACHE_VERSION = 3;
+
+  explicit CssParser(std::string cachePath) : cachePath(std::move(cachePath)) {}
   ~CssParser() = default;
 
   // Non-copyable
@@ -76,28 +80,40 @@ class CssParser {
    */
   void clear() { rulesBySelector_.clear(); }
 
+  /**
+   * Check if CSS rules cache file exists
+   */
+  bool hasCache() const;
+
+  /**
+   * Delete CSS rules cache file exists
+   */
+  void deleteCache() const;
+
   /**
    * Save parsed CSS rules to a cache file.
-   * @param file Open file handle to write to
    * @return true if cache was written successfully
    */
-  bool saveToCache(FsFile& file) const;
+  bool saveToCache() const;
 
   /**
    * Load CSS rules from a cache file.
    * Clears any existing rules before loading.
-   * @param file Open file handle to read from
    * @return true if cache was loaded successfully
    */
-  bool loadFromCache(FsFile& file);
+  bool loadFromCache();
 
  private:
   // Storage: maps normalized selector -> style properties
   std::unordered_map<std::string, CssStyle> rulesBySelector_;
 
+  std::string cachePath;
+
   // Internal parsing helpers
-  void processRuleBlock(const std::string& selectorGroup, const std::string& declarations);
+  void processRuleBlockWithStyle(const std::string& selectorGroup, const CssStyle& style);
   static CssStyle parseDeclarations(const std::string& declBlock);
+  static void parseDeclarationIntoStyle(const std::string& decl, CssStyle& style, std::string& propNameBuf,
+                                        std::string& propValueBuf);
 
   // Individual property value parsers
   static CssTextAlign interpretAlignment(const std::string& val);
@@ -105,10 +121,12 @@ class CssParser {
   static CssFontWeight interpretFontWeight(const std::string& val);
   static CssTextDecoration interpretDecoration(const std::string& val);
   static CssLength interpretLength(const std::string& val);
-  static int8_t interpretSpacing(const std::string& val);
+  /** Returns true only when a numeric length was parsed (e.g. 2em, 50%). False for auto/inherit/initial. */
+  static bool tryInterpretLength(const std::string& val, CssLength& out);
 
   // String utilities
   static std::string normalized(const std::string& s);
+  static void normalizedInto(const std::string& s, std::string& out);
   static std::vector<std::string> splitOnChar(const std::string& s, char delimiter);
   static std::vector<std::string> splitWhitespace(const std::string& s);
 };

lib/Epub/Epub/css/CssStyle.h

@@ -69,6 +69,8 @@ struct CssPropertyFlags {
   uint16_t paddingBottom : 1;
   uint16_t paddingLeft : 1;
   uint16_t paddingRight : 1;
+  uint16_t imageHeight : 1;
+  uint16_t imageWidth : 1;
 
   CssPropertyFlags()
       : textAlign(0),
@@ -83,17 +85,21 @@ struct CssPropertyFlags {
         paddingTop(0),
         paddingBottom(0),
         paddingLeft(0),
-        paddingRight(0) {}
+        paddingRight(0),
+        imageHeight(0),
+        imageWidth(0) {}
 
   [[nodiscard]] bool anySet() const {
     return textAlign || fontStyle || fontWeight || textDecoration || textIndent || marginTop || marginBottom ||
-           marginLeft || marginRight || paddingTop || paddingBottom || paddingLeft || paddingRight;
+           marginLeft || marginRight || paddingTop || paddingBottom || paddingLeft || paddingRight || imageHeight ||
+           imageWidth;
   }
 
   void clearAll() {
     textAlign = fontStyle = fontWeight = textDecoration = textIndent = 0;
     marginTop = marginBottom = marginLeft = marginRight = 0;
     paddingTop = paddingBottom = paddingLeft = paddingRight = 0;
+    imageHeight = imageWidth = 0;
   }
 };
 
@@ -115,6 +121,8 @@ struct CssStyle {
   CssLength paddingBottom;  // Padding after
   CssLength paddingLeft;    // Padding left
   CssLength paddingRight;   // Padding right
+  CssLength imageHeight;    // Height for img (e.g. 2em) – width derived from aspect ratio when only height set
+  CssLength imageWidth;     // Width for img when both or only width set
 
   CssPropertyFlags defined;  // Tracks which properties were explicitly set
 
@@ -173,6 +181,14 @@ struct CssStyle {
       paddingRight = base.paddingRight;
       defined.paddingRight = 1;
     }
+    if (base.hasImageHeight()) {
+      imageHeight = base.imageHeight;
+      defined.imageHeight = 1;
+    }
+    if (base.hasImageWidth()) {
+      imageWidth = base.imageWidth;
+      defined.imageWidth = 1;
+    }
   }
 
   [[nodiscard]] bool hasTextAlign() const { return defined.textAlign; }
@@ -188,6 +204,8 @@ struct CssStyle {
   [[nodiscard]] bool hasPaddingBottom() const { return defined.paddingBottom; }
   [[nodiscard]] bool hasPaddingLeft() const { return defined.paddingLeft; }
   [[nodiscard]] bool hasPaddingRight() const { return defined.paddingRight; }
+  [[nodiscard]] bool hasImageHeight() const { return defined.imageHeight; }
+  [[nodiscard]] bool hasImageWidth() const { return defined.imageWidth; }
 
   void reset() {
     textAlign = CssTextAlign::Left;
@@ -197,6 +215,7 @@ struct CssStyle {
     textIndent = CssLength{};
     marginTop = marginBottom = marginLeft = marginRight = CssLength{};
     paddingTop = paddingBottom = paddingLeft = paddingRight = CssLength{};
+    imageHeight = imageWidth = CssLength{};
     defined.clearAll();
   }
 };

lib/Epub/Epub/hyphenation/HyphenationCommon.cpp

@@ -174,6 +174,213 @@ std::vector<CodepointInfo> collectCodepoints(const std::string& word) {
   while (*ptr != 0) {
     const unsigned char* current = ptr;
     const uint32_t cp = utf8NextCodepoint(&ptr);
+    // If this is a combining diacritic (e.g., U+0301 = acute) and there's
+    // a previous base character that can be composed into a single
+    // precomposed Unicode scalar (Latin-1 / Latin-Extended), do that
+    // composition here. This provides lightweight NFC-like behavior for
+    // common Western European diacritics (acute, grave, circumflex, tilde,
+    // diaeresis, cedilla) without pulling in a full Unicode normalization
+    // library.
+    if (!cps.empty()) {
+      uint32_t prev = cps.back().value;
+      uint32_t composed = 0;
+      switch (cp) {
+        case 0x0300:  // grave
+          switch (prev) {
+            case 0x0041:
+              composed = 0x00C0;
+              break;  // A -> À
+            case 0x0061:
+              composed = 0x00E0;
+              break;  // a -> à
+            case 0x0045:
+              composed = 0x00C8;
+              break;  // E -> È
+            case 0x0065:
+              composed = 0x00E8;
+              break;  // e -> è
+            case 0x0049:
+              composed = 0x00CC;
+              break;  // I -> Ì
+            case 0x0069:
+              composed = 0x00EC;
+              break;  // i -> ì
+            case 0x004F:
+              composed = 0x00D2;
+              break;  // O -> Ò
+            case 0x006F:
+              composed = 0x00F2;
+              break;  // o -> ò
+            case 0x0055:
+              composed = 0x00D9;
+              break;  // U -> Ù
+            case 0x0075:
+              composed = 0x00F9;
+              break;  // u -> ù
+            default:
+              break;
+          }
+          break;
+        case 0x0301:  // acute
+          switch (prev) {
+            case 0x0041:
+              composed = 0x00C1;
+              break;  // A -> Á
+            case 0x0061:
+              composed = 0x00E1;
+              break;  // a -> á
+            case 0x0045:
+              composed = 0x00C9;
+              break;  // E -> É
+            case 0x0065:
+              composed = 0x00E9;
+              break;  // e -> é
+            case 0x0049:
+              composed = 0x00CD;
+              break;  // I -> Í
+            case 0x0069:
+              composed = 0x00ED;
+              break;  // i -> í
+            case 0x004F:
+              composed = 0x00D3;
+              break;  // O -> Ó
+            case 0x006F:
+              composed = 0x00F3;
+              break;  // o -> ó
+            case 0x0055:
+              composed = 0x00DA;
+              break;  // U -> Ú
+            case 0x0075:
+              composed = 0x00FA;
+              break;  // u -> ú
+            case 0x0059:
+              composed = 0x00DD;
+              break;  // Y -> Ý
+            case 0x0079:
+              composed = 0x00FD;
+              break;  // y -> ý
+            default:
+              break;
+          }
+          break;
+        case 0x0302:  // circumflex
+          switch (prev) {
+            case 0x0041:
+              composed = 0x00C2;
+              break;  // A -> Â
+            case 0x0061:
+              composed = 0x00E2;
+              break;  // a -> â
+            case 0x0045:
+              composed = 0x00CA;
+              break;  // E -> Ê
+            case 0x0065:
+              composed = 0x00EA;
+              break;  // e -> ê
+            case 0x0049:
+              composed = 0x00CE;
+              break;  // I -> Î
+            case 0x0069:
+              composed = 0x00EE;
+              break;  // i -> î
+            case 0x004F:
+              composed = 0x00D4;
+              break;  // O -> Ô
+            case 0x006F:
+              composed = 0x00F4;
+              break;  // o -> ô
+            case 0x0055:
+              composed = 0x00DB;
+              break;  // U -> Û
+            case 0x0075:
+              composed = 0x00FB;
+              break;  // u -> û
+            default:
+              break;
+          }
+          break;
+        case 0x0303:  // tilde
+          switch (prev) {
+            case 0x0041:
+              composed = 0x00C3;
+              break;  // A -> Ã
+            case 0x0061:
+              composed = 0x00E3;
+              break;  // a -> ã
+            case 0x004E:
+              composed = 0x00D1;
+              break;  // N -> Ñ
+            case 0x006E:
+              composed = 0x00F1;
+              break;  // n -> ñ
+            default:
+              break;
+          }
+          break;
+        case 0x0308:  // diaeresis/umlaut
+          switch (prev) {
+            case 0x0041:
+              composed = 0x00C4;
+              break;  // A -> Ä
+            case 0x0061:
+              composed = 0x00E4;
+              break;  // a -> ä
+            case 0x0045:
+              composed = 0x00CB;
+              break;  // E -> Ë
+            case 0x0065:
+              composed = 0x00EB;
+              break;  // e -> ë
+            case 0x0049:
+              composed = 0x00CF;
+              break;  // I -> Ï
+            case 0x0069:
+              composed = 0x00EF;
+              break;  // i -> ï
+            case 0x004F:
+              composed = 0x00D6;
+              break;  // O -> Ö
+            case 0x006F:
+              composed = 0x00F6;
+              break;  // o -> ö
+            case 0x0055:
+              composed = 0x00DC;
+              break;  // U -> Ü
+            case 0x0075:
+              composed = 0x00FC;
+              break;  // u -> ü
+            case 0x0059:
+              composed = 0x0178;
+              break;  // Y -> Ÿ
+            case 0x0079:
+              composed = 0x00FF;
+              break;  // y -> ÿ
+            default:
+              break;
+          }
+          break;
+        case 0x0327:  // cedilla
+          switch (prev) {
+            case 0x0043:
+              composed = 0x00C7;
+              break;  // C -> Ç
+            case 0x0063:
+              composed = 0x00E7;
+              break;  // c -> ç
+            default:
+              break;
+          }
+          break;
+        default:
+          break;
+      }
+
+      if (composed != 0) {
+        cps.back().value = composed;
+        continue;  // skip pushing the combining mark itself
+      }
+    }
+
     cps.push_back({cp, static_cast<size_t>(current - base)});
   }
 

lib/Epub/Epub/hyphenation/Hyphenator.cpp

@@ -1,8 +1,10 @@
 #include "Hyphenator.h"
 
+#include <algorithm>
 #include <vector>
 
 #include "HyphenationCommon.h"
+#include "LanguageHyphenator.h"
 #include "LanguageRegistry.h"
 
 const LanguageHyphenator* Hyphenator::cachedHyphenator_ = nullptr;
@@ -32,10 +34,19 @@ size_t byteOffsetForIndex(const std::vector<CodepointInfo>& cps, const size_t in
 }
 
 // Builds a vector of break information from explicit hyphen markers in the given codepoints.
+// Only hyphens that appear between two alphabetic characters are considered valid breaks.
+//
+// Example: "US-Satellitensystems" (cps: U, S, -, S, a, t, ...)
+//   -> finds '-' at index 2 with alphabetic neighbors 'S' and 'S'
+//   -> returns one BreakInfo at the byte offset of 'S' (the char after '-'),
+//      with requiresInsertedHyphen=false because '-' is already visible.
+//
+// Example: "Satel\u00ADliten" (soft-hyphen between 'l' and 'l')
+//   -> returns one BreakInfo with requiresInsertedHyphen=true (soft-hyphen
+//      is invisible and needs a visible '-' when the break is used).
 std::vector<Hyphenator::BreakInfo> buildExplicitBreakInfos(const std::vector<CodepointInfo>& cps) {
   std::vector<Hyphenator::BreakInfo> breaks;
 
-  // Scan every codepoint looking for explicit/soft hyphen markers that are surrounded by letters.
   for (size_t i = 1; i + 1 < cps.size(); ++i) {
     const uint32_t cp = cps[i].value;
     if (!isExplicitHyphen(cp) || !isAlphabetic(cps[i - 1].value) || !isAlphabetic(cps[i + 1].value)) {
@@ -63,6 +74,43 @@ std::vector<Hyphenator::BreakInfo> Hyphenator::breakOffsets(const std::string& w
   // Explicit hyphen markers (soft or hard) take precedence over language breaks.
   auto explicitBreakInfos = buildExplicitBreakInfos(cps);
   if (!explicitBreakInfos.empty()) {
+    // When a word contains explicit hyphens we also run Liang patterns on each alphabetic
+    // segment between them. Without this, "US-Satellitensystems" would only offer one split
+    // point (after "US-"), making it impossible to break mid-"Satellitensystems" even when
+    // "US-Satelliten-" would fit on the line.
+    //
+    // Example: "US-Satellitensystems"
+    //   Segments: ["US", "Satellitensystems"]
+    //   Explicit break: after "US-"           -> @3  (no inserted hyphen)
+    //   Pattern breaks on "Satellitensystems" -> @5  Sa|tel  (+hyphen)
+    //                                            @8  Satel|li  (+hyphen)
+    //                                            @10 Satelli|ten  (+hyphen)
+    //                                            @13 Satelliten|sys  (+hyphen)
+    //                                            @16 Satellitensys|tems  (+hyphen)
+    //   Result: 6 sorted break points; the line-breaker picks the widest prefix that fits.
+    if (hyphenator) {
+      size_t segStart = 0;
+      for (size_t i = 0; i <= cps.size(); ++i) {
+        const bool atEnd = (i == cps.size());
+        const bool atHyphen = !atEnd && isExplicitHyphen(cps[i].value);
+        if (atEnd || atHyphen) {
+          if (i > segStart) {
+            std::vector<CodepointInfo> segment(cps.begin() + segStart, cps.begin() + i);
+            auto segIndexes = hyphenator->breakIndexes(segment);
+            for (const size_t idx : segIndexes) {
+              const size_t cpIdx = segStart + idx;
+              if (cpIdx < cps.size()) {
+                explicitBreakInfos.push_back({cps[cpIdx].byteOffset, true});
+              }
+            }
+          }
+          segStart = i + 1;
+        }
+      }
+      // Merge explicit and pattern breaks into ascending byte-offset order.
+      std::sort(explicitBreakInfos.begin(), explicitBreakInfos.end(),
+                [](const BreakInfo& a, const BreakInfo& b) { return a.byteOffset < b.byteOffset; });
+    }
     return explicitBreakInfos;
   }
 

lib/Epub/Epub/hyphenation/Hyphenator.h

@@ -9,11 +9,24 @@ class LanguageHyphenator;
 class Hyphenator {
  public:
   struct BreakInfo {
-    size_t byteOffset;
-    bool requiresInsertedHyphen;
+    size_t byteOffset;            // Byte position inside the UTF-8 word where a break may occur.
+    bool requiresInsertedHyphen;  // true = a visible '-' must be rendered at the break (pattern/fallback breaks).
+                                  // false = the word already contains a hyphen at this position (explicit '-').
   };
-  // Returns byte offsets where the word may be hyphenated. When includeFallback is true, all positions obeying the
-  // minimum prefix/suffix constraints are returned even if no language-specific rule matches.
+
+  // Returns byte offsets where the word may be hyphenated.
+  //
+  // Break sources (in priority order):
+  //   1. Explicit hyphens already present in the word (e.g. '-' or soft-hyphen U+00AD).
+  //      When found, language patterns are additionally run on each alphabetic segment
+  //      between hyphens so compound words can break within their parts.
+  //      Example: "US-Satellitensystems" yields breaks after "US-" (no inserted hyphen)
+  //               plus pattern breaks inside "Satellitensystems" (Sa|tel|li|ten|sys|tems).
+  //   2. Language-specific Liang patterns (e.g. German de_patterns).
+  //      Example: "Quadratkilometer" -> Qua|drat|ki|lo|me|ter.
+  //   3. Fallback every-N-chars splitting (only when includeFallback is true AND no
+  //      pattern breaks were found). Used as a last resort to prevent a single oversized
+  //      word from overflowing the page width.
   static std::vector<BreakInfo> breakOffsets(const std::string& word, bool includeFallback);
 
   // Provide a publication-level language hint (e.g. "en", "en-US", "ru") used to select hyphenation rules.