Merge remote-tracking branch 'upstream/master' into feature/koreader-sync

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,9 +1,18 @@
 ## Summary
 
-* **What is the goal of this PR?** (e.g., Fixes a bug in the user authentication module, Implements the new feature for 
+* **What is the goal of this PR?** (e.g., Implements the new feature for file uploading.)
-  file uploading.)
 * **What changes are included?**
 
 ## Additional Context
 
-* Add any other information that might be helpful for the reviewer (e.g., performance implications, potential risks, specific areas to focus on).
+* Add any other information that might be helpful for the reviewer (e.g., performance implications, potential risks, 
+  specific areas to focus on).
+
+---
+
+### AI Usage
+
+While CrossPoint doesn't have restrictions on AI tools in contributing, please be transparent about their usage as it 
+helps set the right context for reviewers.
+
+Did you use AI tools to help write this code? _**< YES | PARTIALLY | NO >**_

.github/workflows/ci.yml

@@ -7,11 +7,11 @@ name: CI
 jobs:
   build:
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v6
         with:
           submodules: recursive
+
       - uses: actions/setup-python@v6
         with:
           python-version: '3.14'

.github/workflows/release.yml

@@ -7,17 +7,18 @@ on:
 jobs:
   build-release:
     runs-on: ubuntu-latest
-
     steps:
       - uses: actions/checkout@v6
         with:
           submodules: recursive
+
       - uses: actions/cache@v5
         with:
           path: |
             ~/.cache/pip
             ~/.platformio/.cache
           key: ${{ runner.os }}-pio
+
       - uses: actions/setup-python@v6
         with:
           python-version: '3.14'

USER_GUIDE.md

@@ -1,17 +1,16 @@
 # CrossPoint User Guide
 
-Welcome to the **CrossPoint** firmware. This guide outlines the hardware controls, navigation, and reading features of 
+Welcome to the **CrossPoint** firmware. This guide outlines the hardware controls, navigation, and reading features of the device.
-the device.
 
 ## 1. Hardware Overview
 
 The device utilises the standard buttons on the Xtink X4 (in the same layout as the manufacturer firmware, by default):
 
 ### Button Layout
-| Location        | Buttons                                    |
+| Location        | Buttons                                              |
-|-----------------|--------------------------------------------|
+| --------------- | ---------------------------------------------------- |
-| **Bottom Edge** | **Back**, **Confirm**, **Left**, **Right** |
+| **Bottom Edge** | **Back**, **Confirm**, **Left**, **Right**           |
-| **Right Side**  | **Power**, **Volume Up**, **Volume Down**  |
+| **Right Side**  | **Power**, **Volume Up**, **Volume Down**, **Reset** |
 
 Button layout can be customized in **[Settings](#35-settings)**.
 
@@ -21,8 +20,9 @@ Button layout can be customized in **[Settings](#35-settings)**.
 
 ### Power On / Off
 
-To turn the device on or off, **press and hold the Power button for half a second**. In **[Settings](#35-settings)** you can configure
+To turn the device on or off, **press and hold the Power button for half a second**. In **[Settings](#35-settings)** you can configure the power button to trigger on a short press instead of a long one.
-the power button to trigger on a short press instead of a long one.
+
+To reboot the device (for example if it's frozen, or after a firmware update), press and release the Reset button, and then hold the Power button for a few seconds.
 
 ### First Launch
 
@@ -37,15 +37,13 @@ Upon turning the device on for the first time, you will be placed on the **[Home
 
 ### 3.1 Home Screen
 
-The Home Screen is the main entry point to the firmware. From here you can navigate to **[Reading Mode](#4-reading-mode)** with the most recently read book, **[Book Selection](#32-book-selection)**,
+The Home Screen is the main entry point to the firmware. From here you can navigate to **[Reading Mode](#4-reading-mode)** with the most recently read book, **[Book Selection](#32-book-selection)**, **[Settings](#35-settings)**, or the **[File Upload](#34-file-upload-screen)** screen.
-**[Settings](#35-settings)**, or the **[File Upload](#34-file-upload-screen)** screen.
 
 ### 3.2 Book Selection
 
 The Book Selection acts as a folder and file browser.
 
-* **Navigate List:** Use **Left** (or **Volume Up**), or **Right** (or **Volume Down**) to move the selection cursor up 
+* **Navigate List:** Use **Left** (or **Volume Up**), or **Right** (or **Volume Down**) to move the selection cursor up and down through folders and books. You can also long-press these buttons to scroll a full page up or down.
-  and down through folders and books.
 * **Open Selection:** Press **Confirm** to open a folder or read a selected book.
 
 ### 3.3 Reading Mode
@@ -54,42 +52,47 @@ See [Reading Mode](#4-reading-mode) below for more information.
 
 ### 3.4 File Upload Screen
 
-The File Upload screen allows you to upload new e-books to the device. When you enter the screen, you'll be prompted with
+The File Upload screen allows you to upload new e-books to the device. When you enter the screen, you'll be prompted with a WiFi selection dialog and then your X4 will start hosting a web server.
-a WiFi selection dialog and then your X4 will start hosting a web server.
 
 See the [webserver docs](./docs/webserver.md) for more information on how to connect to the web server and upload files.
 
+> [!TIP]
+> Advanced users can also manage files programmatically or via the command line using `curl`. See the [webserver docs](./docs/webserver.md) for details.
+
 ### 3.5 Settings
 
 The Settings screen allows you to configure the device's behavior. There are a few settings you can adjust:
-- **Sleep Screen**: Which sleep screen to display when the device sleeps, options are:
+- **Sleep Screen**: Which sleep screen to display when the device sleeps:
   - "Dark" (default) - The default dark sleep screen
   - "Light" - The same default sleep screen, on a white background
   - "Custom" - Custom images from the SD card, see [Sleep Screen](#36-sleep-screen) below for more information
   - "Cover" - The book cover image (Note: this is experimental and may not work as expected)
-- **Status Bar**: Configure the status bar displayed while reading, options are:
+  - "Blank" - A blank screen
+- **Status Bar**: Configure the status bar displayed while reading:
   - "None" - No status bar
   - "No Progress" - Show status bar without reading progress
   - "Full" - Show status bar with reading progress
-- **Extra Paragraph Spacing**: If enabled, vertical space will be added between paragraphs in the book, if disabled,
+- **Extra Paragraph Spacing**: If enabled, vertical space will be added between paragraphs in the book. If disabled, paragraphs will not have vertical space between them, but will have first-line indentation.
-  paragraphs will not have vertical space between them, but will have first word indentation.
 - **Short Power Button Click**: Whether to trigger the power button on a short press or a long press.
-- **Reading Orientation**: Set the screen orientation for reading, options are:
+- **Reading Orientation**: Set the screen orientation for reading:
   - "Portrait" (default) - Standard portrait orientation
   - "Landscape CW" - Landscape, rotated clockwise
   - "Inverted" - Portrait, upside down
   - "Landscape CCW" - Landscape, rotated counter-clockwise
-- **Front Button Layout**: Configure the order of the bottom edge buttons, options are:
+- **Front Button Layout**: Configure the order of the bottom edge buttons:
-  - "Bck, Cnfrm, Lft, Rght" (default) - Back, Confirm, Left, Right
+  - Back, Confirm, Left, Right (default)
-  - "Lft, Rght, Bck, Cnfrm" - Left, Right, Back, Confirm
+  - Left, Right, Back, Confirm
-  - "Lft, Bck, Cnfrm, Rght" - Left, Back, Confirm, Right
+  - Left, Back, Confirm, Right
-- **Side Button Layout**: Swap the order of the volume buttons from Previous/Next to Next/Previous. This change is only in effect when reading.
+- **Side Button Layout**: Swap the order of the up and down volume buttons from Previous/Next to Next/Previous. This change is only in effect when reading.
-- **Reader Font Family**: Choose the font used for reading, options are:
+- **Reader Font Family**: Choose the font used for reading:
   - "Bookerly" (default) - Amazon's reading font
   - "Noto Sans" - Google's sans-serif font
   - "Open Dyslexic" - Font designed for readers with dyslexia
-- **Reader Font Size**: Adjust the text size for reading, options are "Small", "Medium", "Large", or "X Large".
+- **Reader Font Size**: Adjust the text size for reading; options are "Small", "Medium", "Large", or "X Large".
-- **Reader Line Spacing**: Adjust the spacing between lines, options are "Tight", "Normal", or "Wide".
+- **Reader Line Spacing**: Adjust the spacing between lines; options are "Tight", "Normal", or "Wide".
+- **Reader Paragraph Alignment**: Set the alignment of paragraphs; options are "Justified" (default), "Left", "Center", or "Right".
+- **Time to Sleep**: Set the duration of inactivity before the device automatically goes to sleep.
+- **Refresh Frequency**: Set how often the screen does a full refresh while reading to reduce ghosting.
 - **Check for updates**: Check for firmware updates over WiFi.
 
 ### 3.6 Sleep Screen
@@ -97,9 +100,7 @@ The Settings screen allows you to configure the device's behavior. There are a f
 You can customize the sleep screen by placing custom images in specific locations on the SD card:
 
 - **Single Image:** Place a file named `sleep.bmp` in the root directory.
-- **Multiple Images:** Create a `sleep` directory in the root of the SD card and place any number of `.bmp` images
+- **Multiple Images:** Create a `sleep` directory in the root of the SD card and place any number of `.bmp` images inside. If images are found in this directory, they will take priority over the `sleep.bmp` file, and one will be randomly selected each time the device sleeps.
-  inside. If images are found in this directory, they will take priority over the `sleep.bmp` file, and one will be
-  randomly selected each time the device sleeps.
 
 > [!NOTE]
 > You'll need to set the **Sleep Screen** setting to **Custom** in order to use these images.
@@ -117,17 +118,19 @@ Once you have opened a book, the button layout changes to facilitate reading.
 
 ### Page Turning
 | Action            | Buttons                              |
-|-------------------|--------------------------------------|
+| ----------------- | ------------------------------------ |
 | **Previous Page** | Press **Left** _or_ **Volume Up**    |
 | **Next Page**     | Press **Right** _or_ **Volume Down** |
 
+The role of the volume (side) buttons can be swapped in **[Settings](#35-settings)**.
+
 ### Chapter Navigation
 * **Next Chapter:** Press and **hold** the **Right** (or **Volume Down**) button briefly, then release.
 * **Previous Chapter:** Press and **hold** the **Left** (or **Volume Up**) button briefly, then release.
 
 ### System Navigation
 * **Return to Book Selection:** Press **Back** to close the book and return to the **[Book Selection](#32-book-selection)** screen.
-* **Return to Home:** Press and hold **Back** to close the book and return to the **[Home](#31-home-screen)** screen.
+* **Return to Home:** Press and **hold** the **Back** button to close the book and return to the **[Home](#31-home-screen)** screen.
 * **Chapter Menu:** Press **Confirm** to open the **[Table of Contents/Chapter Selection](#5-chapter-selection-screen)**.
 
 ---
@@ -144,7 +147,6 @@ Accessible by pressing **Confirm** while inside a book.
 
 ## 6. Current Limitations & Roadmap
 
-Please note that this firmware is currently in active development. The following features are **not yet supported** but
+Please note that this firmware is currently in active development. The following features are **not yet supported** but are planned for future updates:
-are planned for future updates:
 
 * **Images:** Embedded images in e-books will not render.

docs/webserver.md

@@ -170,6 +170,40 @@ This is useful for organizing your ebooks by genre, author, or series.
 
 ---
 
+## 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. 
+
+### Uploading a File
+To upload a file to the root directory, use the following command:
+```bash
+curl -F "file=@book.epub" "http://crosspoint.local/upload?path=/"
+```
+
+* **`-F "file=@filename"`**: Points to the local file on your computer.
+* **`path=/`**: The destination folder on the device SD card.
+
+### Deleting a File
+
+To delete a specific file, provide the full path on the SD card:
+
+```bash
+curl -F "path=/folder/file.epub" "http://crosspoint.local/delete"
+```
+
+### Advanced Flags
+
+For more reliable transfers of large EPUB files, consider adding these flags:
+
+* `-#`: Shows a simple progress bar.
+* `--connect-timeout 30`: Limits how long curl waits to establish a connection (in seconds).
+* `--max-time 300`: Sets a maximum duration for the entire transfer (5 minutes).
+
+> [!NOTE]
+> These examples use `crosspoint.local`. If your network does not support mDNS or the address does not resolve, replace it with the specific **IP Address** displayed on your device screen (e.g., `http://192.168.1.102/`).
+
+---
+
 ## Troubleshooting
 
 ### Cannot See the Device on the Network

lib/Epub/Epub.cpp

@@ -167,7 +167,10 @@ bool Epub::parseTocNavFile() const {
   }
   const auto navSize = tempNavFile.size();
 
-  TocNavParser navParser(contentBasePath, navSize, bookMetadataCache.get());
+  // Note: We can't use `contentBasePath` here as the nav file may be in a different folder to the content.opf
+  // and the HTMLX nav file will have hrefs relative to itself
+  const std::string navContentBasePath = tocNavItem.substr(0, tocNavItem.find_last_of('/') + 1);
+  TocNavParser navParser(navContentBasePath, navSize, bookMetadataCache.get());
 
   if (!navParser.setup()) {
     Serial.printf("[%lu] [EBP] Could not setup toc nav parser\n", millis());
@@ -345,11 +348,14 @@ const std::string& Epub::getAuthor() const {
   return bookMetadataCache->coreMetadata.author;
 }
 
-std::string Epub::getCoverBmpPath() const { return cachePath + "/cover.bmp"; }
+std::string Epub::getCoverBmpPath(bool cropped) const {
+  const auto coverFileName = "cover" + cropped ? "_crop" : "";
+  return cachePath + "/" + coverFileName + ".bmp";
+}
 
-bool Epub::generateCoverBmp() const {
+bool Epub::generateCoverBmp(bool cropped) const {
   // Already generated, return true
-  if (SdMan.exists(getCoverBmpPath().c_str())) {
+  if (SdMan.exists(getCoverBmpPath(cropped).c_str())) {
     return true;
   }
 
@@ -381,7 +387,7 @@ bool Epub::generateCoverBmp() const {
     }
 
     FsFile coverBmp;
-    if (!SdMan.openFileForWrite("EBP", getCoverBmpPath(), coverBmp)) {
+    if (!SdMan.openFileForWrite("EBP", getCoverBmpPath(cropped), coverBmp)) {
       coverJpg.close();
       return false;
     }
@@ -392,7 +398,7 @@ bool Epub::generateCoverBmp() const {
 
     if (!success) {
       Serial.printf("[%lu] [EBP] Failed to generate BMP from JPG cover image\n", millis());
-      SdMan.remove(getCoverBmpPath().c_str());
+      SdMan.remove(getCoverBmpPath(cropped).c_str());
     }
     Serial.printf("[%lu] [EBP] Generated BMP from JPG cover image, success: %s\n", millis(), success ? "yes" : "no");
     return success;

lib/Epub/Epub.h

@@ -44,8 +44,8 @@ class Epub {
   const std::string& getPath() const;
   const std::string& getTitle() const;
   const std::string& getAuthor() const;
-  std::string getCoverBmpPath() const;
+  std::string getCoverBmpPath(bool cropped = false) const;
-  bool generateCoverBmp() const;
+  bool generateCoverBmp(bool cropped = false) const;
   uint8_t* readItemContentsToBytes(const std::string& itemHref, size_t* size = nullptr,
                                    bool trailingNullByte = false) const;
   bool readItemContentsToStream(const std::string& itemHref, Print& out, size_t chunkSize) const;

lib/Epub/Epub/BookMetadataCache.cpp

@@ -9,7 +9,7 @@
 #include "FsHelpers.h"
 
 namespace {
-constexpr uint8_t BOOK_CACHE_VERSION = 3;
+constexpr uint8_t BOOK_CACHE_VERSION = 4;
 constexpr char bookBinFile[] = "/book.bin";
 constexpr char tmpSpineBinFile[] = "/spine.bin.tmp";
 constexpr char tmpTocBinFile[] = "/toc.bin.tmp";

lib/Epub/Epub/htmlEntities.cpp

@@ -1,163 +0,0 @@
-// from
-// https://github.com/atomic14/diy-esp32-epub-reader/blob/2c2f57fdd7e2a788d14a0bcb26b9e845a47aac42/lib/Epub/RubbishHtmlParser/htmlEntities.cpp
-
-#include "htmlEntities.h"
-
-#include <cstring>
-#include <unordered_map>
-
-const int MAX_ENTITY_LENGTH = 10;
-
-// Use book: entities_ww2.epub to test this (Page 7: Entities parser test)
-// Note the supported keys are only in lowercase
-// Store the mappings in a unordered hash map
-static std::unordered_map<std::string, std::string> entity_lookup(
-    {{"&quot;", "\""},  {"&frasl;", "⁄"},   {"&amp;", "&"},      {"&lt;", "<"},     {"&gt;", ">"},
-     {"&Agrave;", "À"}, {"&Aacute;", "Á"},  {"&Acirc;", "Â"},    {"&Atilde;", "Ã"}, {"&Auml;", "Ä"},
-     {"&Aring;", "Å"},  {"&AElig;", "Æ"},   {"&Ccedil;", "Ç"},   {"&Egrave;", "È"}, {"&Eacute;", "É"},
-     {"&Ecirc;", "Ê"},  {"&Euml;", "Ë"},    {"&Igrave;", "Ì"},   {"&Iacute;", "Í"}, {"&Icirc;", "Î"},
-     {"&Iuml;", "Ï"},   {"&ETH;", "Ð"},     {"&Ntilde;", "Ñ"},   {"&Ograve;", "Ò"}, {"&Oacute;", "Ó"},
-     {"&Ocirc;", "Ô"},  {"&Otilde;", "Õ"},  {"&Ouml;", "Ö"},     {"&Oslash;", "Ø"}, {"&Ugrave;", "Ù"},
-     {"&Uacute;", "Ú"}, {"&Ucirc;", "Û"},   {"&Uuml;", "Ü"},     {"&Yacute;", "Ý"}, {"&THORN;", "Þ"},
-     {"&szlig;", "ß"},  {"&agrave;", "à"},  {"&aacute;", "á"},   {"&acirc;", "â"},  {"&atilde;", "ã"},
-     {"&auml;", "ä"},   {"&aring;", "å"},   {"&aelig;", "æ"},    {"&ccedil;", "ç"}, {"&egrave;", "è"},
-     {"&eacute;", "é"}, {"&ecirc;", "ê"},   {"&euml;", "ë"},     {"&igrave;", "ì"}, {"&iacute;", "í"},
-     {"&icirc;", "î"},  {"&iuml;", "ï"},    {"&eth;", "ð"},      {"&ntilde;", "ñ"}, {"&ograve;", "ò"},
-     {"&oacute;", "ó"}, {"&ocirc;", "ô"},   {"&otilde;", "õ"},   {"&ouml;", "ö"},   {"&oslash;", "ø"},
-     {"&ugrave;", "ù"}, {"&uacute;", "ú"},  {"&ucirc;", "û"},    {"&uuml;", "ü"},   {"&yacute;", "ý"},
-     {"&thorn;", "þ"},  {"&yuml;", "ÿ"},    {"&nbsp;", " "},     {"&iexcl;", "¡"},  {"&cent;", "¢"},
-     {"&pound;", "£"},  {"&curren;", "¤"},  {"&yen;", "¥"},      {"&brvbar;", "¦"}, {"&sect;", "§"},
-     {"&uml;", "¨"},    {"&copy;", "©"},    {"&ordf;", "ª"},     {"&laquo;", "«"},  {"&not;", "¬"},
-     {"&shy;", "­"},    {"&reg;", "®"},     {"&macr;", "¯"},     {"&deg;", "°"},    {"&plusmn;", "±"},
-     {"&sup2;", "²"},   {"&sup3;", "³"},    {"&acute;", "´"},    {"&micro;", "µ"},  {"&para;", "¶"},
-     {"&cedil;", "¸"},  {"&sup1;", "¹"},    {"&ordm;", "º"},     {"&raquo;", "»"},  {"&frac14;", "¼"},
-     {"&frac12;", "½"}, {"&frac34;", "¾"},  {"&iquest;", "¿"},   {"&times;", "×"},  {"&divide;", "÷"},
-     {"&forall;", "∀"}, {"&part;", "∂"},    {"&exist;", "∃"},    {"&empty;", "∅"},  {"&nabla;", "∇"},
-     {"&isin;", "∈"},   {"&notin;", "∉"},   {"&ni;", "∋"},       {"&prod;", "∏"},   {"&sum;", "∑"},
-     {"&minus;", "−"},  {"&lowast;", "∗"},  {"&radic;", "√"},    {"&prop;", "∝"},   {"&infin;", "∞"},
-     {"&ang;", "∠"},    {"&and;", "∧"},     {"&or;", "∨"},       {"&cap;", "∩"},    {"&cup;", "∪"},
-     {"&int;", "∫"},    {"&there4;", "∴"},  {"&sim;", "∼"},      {"&cong;", "≅"},   {"&asymp;", "≈"},
-     {"&ne;", "≠"},     {"&equiv;", "≡"},   {"&le;", "≤"},       {"&ge;", "≥"},     {"&sub;", "⊂"},
-     {"&sup;", "⊃"},    {"&nsub;", "⊄"},    {"&sube;", "⊆"},     {"&supe;", "⊇"},   {"&oplus;", "⊕"},
-     {"&otimes;", "⊗"}, {"&perp;", "⊥"},    {"&sdot;", "⋅"},     {"&Alpha;", "Α"},  {"&Beta;", "Β"},
-     {"&Gamma;", "Γ"},  {"&Delta;", "Δ"},   {"&Epsilon;", "Ε"},  {"&Zeta;", "Ζ"},   {"&Eta;", "Η"},
-     {"&Theta;", "Θ"},  {"&Iota;", "Ι"},    {"&Kappa;", "Κ"},    {"&Lambda;", "Λ"}, {"&Mu;", "Μ"},
-     {"&Nu;", "Ν"},     {"&Xi;", "Ξ"},      {"&Omicron;", "Ο"},  {"&Pi;", "Π"},     {"&Rho;", "Ρ"},
-     {"&Sigma;", "Σ"},  {"&Tau;", "Τ"},     {"&Upsilon;", "Υ"},  {"&Phi;", "Φ"},    {"&Chi;", "Χ"},
-     {"&Psi;", "Ψ"},    {"&Omega;", "Ω"},   {"&alpha;", "α"},    {"&beta;", "β"},   {"&gamma;", "γ"},
-     {"&delta;", "δ"},  {"&epsilon;", "ε"}, {"&zeta;", "ζ"},     {"&eta;", "η"},    {"&theta;", "θ"},
-     {"&iota;", "ι"},   {"&kappa;", "κ"},   {"&lambda;", "λ"},   {"&mu;", "μ"},     {"&nu;", "ν"},
-     {"&xi;", "ξ"},     {"&omicron;", "ο"}, {"&pi;", "π"},       {"&rho;", "ρ"},    {"&sigmaf;", "ς"},
-     {"&sigma;", "σ"},  {"&tau;", "τ"},     {"&upsilon;", "υ"},  {"&phi;", "φ"},    {"&chi;", "χ"},
-     {"&psi;", "ψ"},    {"&omega;", "ω"},   {"&thetasym;", "ϑ"}, {"&upsih;", "ϒ"},  {"&piv;", "ϖ"},
-     {"&OElig;", "Œ"},  {"&oelig;", "œ"},   {"&Scaron;", "Š"},   {"&scaron;", "š"}, {"&Yuml;", "Ÿ"},
-     {"&fnof;", "ƒ"},   {"&circ;", "ˆ"},    {"&tilde;", "˜"},    {"&ensp;", ""},    {"&emsp;", ""},
-     {"&thinsp;", ""},  {"&zwnj;", "‌"},  {"&zwj;", "‍"},    {"&lrm;", "‎"},  {"&rlm;", "‏"},
-     {"&ndash;", "–"},  {"&mdash;", "—"},   {"&lsquo;", "‘"},    {"&rsquo;", "’"},  {"&sbquo;", "‚"},
-     {"&ldquo;", "“"},  {"&rdquo;", "”"},   {"&bdquo;", "„"},    {"&dagger;", "†"}, {"&Dagger;", "‡"},
-     {"&bull;", "•"},   {"&hellip;", "…"},  {"&permil;", "‰"},   {"&prime;", "′"},  {"&Prime;", "″"},
-     {"&lsaquo;", "‹"}, {"&rsaquo;", "›"},  {"&oline;", "‾"},    {"&euro;", "€"},   {"&trade;", "™"},
-     {"&larr;", "←"},   {"&uarr;", "↑"},    {"&rarr;", "→"},     {"&darr;", "↓"},   {"&harr;", "↔"},
-     {"&crarr;", "↵"},  {"&lceil;", "⌈"},   {"&rceil;", "⌉"},    {"&lfloor;", "⌊"}, {"&rfloor;", "⌋"},
-     {"&loz;", "◊"},    {"&spades;", "♠"},  {"&clubs;", "♣"},    {"&hearts;", "♥"}, {"&diams;", "♦"}});
-
-// converts from a unicode code point to the utf8 equivalent
-void convert_to_utf8(const int code, std::string& res) {
-  // convert to a utf8 sequence
-  if (code < 0x80) {
-    res += static_cast<char>(code);
-  } else if (code < 0x800) {
-    res += static_cast<char>(0xc0 | (code >> 6));
-    res += static_cast<char>(0x80 | (code & 0x3f));
-  } else if (code < 0x10000) {
-    res += static_cast<char>(0xe0 | (code >> 12));
-    res += static_cast<char>(0x80 | ((code >> 6) & 0x3f));
-    res += static_cast<char>(0x80 | (code & 0x3f));
-  } else if (code < 0x200000) {
-    res += static_cast<char>(0xf0 | (code >> 18));
-    res += static_cast<char>(0x80 | ((code >> 12) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 6) & 0x3f));
-    res += static_cast<char>(0x80 | (code & 0x3f));
-  } else if (code < 0x4000000) {
-    res += static_cast<char>(0xf8 | (code >> 24));
-    res += static_cast<char>(0x80 | ((code >> 18) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 12) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 6) & 0x3f));
-    res += static_cast<char>(0x80 | (code & 0x3f));
-  } else if (code < 0x80000000) {
-    res += static_cast<char>(0xfc | (code >> 30));
-    res += static_cast<char>(0x80 | ((code >> 24) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 18) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 12) & 0x3f));
-    res += static_cast<char>(0x80 | ((code >> 6) & 0x3f));
-  }
-}
-
-// handles numeric entities - e.g. &#1234; or &#x1234;
-bool process_numeric_entity(const std::string& entity, std::string& res) {
-  int code = 0;
-  // is it hex?
-  if (entity[2] == 'x' || entity[2] == 'X') {
-    // parse the hex code
-    code = strtol(entity.substr(3, entity.size() - 3).c_str(), nullptr, 16);
-  } else {
-    code = strtol(entity.substr(2, entity.size() - 3).c_str(), nullptr, 10);
-  }
-  if (code != 0) {
-    // special handling for nbsp
-    if (code == 0xA0) {
-      res += " ";
-    } else {
-      convert_to_utf8(code, res);
-    }
-    return true;
-  }
-  return false;
-}
-
-// handles named entities - e.g. &amp;
-bool process_string_entity(const std::string& entity, std::string& res) {
-  // it's a named entity - find it in the lookup table
-  // find it in the map
-  const auto it = entity_lookup.find(entity);
-  if (it != entity_lookup.end()) {
-    res += it->second;
-    return true;
-  }
-  return false;
-}
-
-// replace all the entities in the string
-std::string replaceHtmlEntities(const char* text) {
-  std::string res;
-  res.reserve(strlen(text));
-  for (int i = 0; i < strlen(text); ++i) {
-    bool flag = false;
-    // do we have a potential entity?
-    if (text[i] == '&') {
-      // find the end of the entity
-      int j = i + 1;
-      while (j < strlen(text) && text[j] != ';' && j - i < MAX_ENTITY_LENGTH) {
-        j++;
-      }
-      if (j - i > 2) {
-        char entity[j - i + 1];
-        strncpy(entity, text + i, j - i);
-        // is it a numeric code?
-        if (entity[1] == '#') {
-          flag = process_numeric_entity(entity, res);
-        } else {
-          flag = process_string_entity(entity, res);
-        }
-        // skip past the entity if we successfully decoded it
-        if (flag) {
-          i = j;
-        }
-      }
-    }
-    if (!flag) {
-      res += text[i];
-    }
-  }
-  return res;
-}

lib/Epub/Epub/htmlEntities.h

@@ -1,7 +0,0 @@
-// from
-// https://github.com/atomic14/diy-esp32-epub-reader/blob/2c2f57fdd7e2a788d14a0bcb26b9e845a47aac42/lib/Epub/RubbishHtmlParser/htmlEntities.cpp
-
-#pragma once
-#include <string>
-
-std::string replaceHtmlEntities(const char* text);

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -6,7 +6,6 @@
 #include <expat.h>
 
 #include "../Page.h"
-#include "../htmlEntities.h"
 
 const char* HEADER_TAGS[] = {"h1", "h2", "h3", "h4", "h5", "h6"};
 constexpr int NUM_HEADER_TAGS = sizeof(HEADER_TAGS) / sizeof(HEADER_TAGS[0]);
@@ -130,7 +129,7 @@ void XMLCALL ChapterHtmlSlimParser::characterData(void* userData, const XML_Char
       // Currently looking at whitespace, if there's anything in the partWordBuffer, flush it
       if (self->partWordBufferIndex > 0) {
         self->partWordBuffer[self->partWordBufferIndex] = '\0';
-        self->currentTextBlock->addWord(std::move(replaceHtmlEntities(self->partWordBuffer)), fontStyle);
+        self->currentTextBlock->addWord(self->partWordBuffer, fontStyle);
         self->partWordBufferIndex = 0;
       }
       // Skip the whitespace char
@@ -155,7 +154,7 @@ void XMLCALL ChapterHtmlSlimParser::characterData(void* userData, const XML_Char
     // If we're about to run out of space, then cut the word off and start a new one
     if (self->partWordBufferIndex >= MAX_WORD_SIZE) {
       self->partWordBuffer[self->partWordBufferIndex] = '\0';
-      self->currentTextBlock->addWord(std::move(replaceHtmlEntities(self->partWordBuffer)), fontStyle);
+      self->currentTextBlock->addWord(self->partWordBuffer, fontStyle);
       self->partWordBufferIndex = 0;
     }
 
@@ -197,7 +196,7 @@ void XMLCALL ChapterHtmlSlimParser::endElement(void* userData, const XML_Char* n
       }
 
       self->partWordBuffer[self->partWordBufferIndex] = '\0';
-      self->currentTextBlock->addWord(std::move(replaceHtmlEntities(self->partWordBuffer)), fontStyle);
+      self->currentTextBlock->addWord(self->partWordBuffer, fontStyle);
       self->partWordBufferIndex = 0;
     }
   }

lib/Epub/Epub/parsers/ContentOpfParser.cpp

@@ -167,7 +167,7 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
       if (strcmp(atts[i], "id") == 0) {
         itemId = atts[i + 1];
       } else if (strcmp(atts[i], "href") == 0) {
-        href = self->baseContentPath + atts[i + 1];
+        href = FsHelpers::normalisePath(self->baseContentPath + atts[i + 1]);
       } else if (strcmp(atts[i], "media-type") == 0) {
         mediaType = atts[i + 1];
       } else if (strcmp(atts[i], "properties") == 0) {
@@ -243,7 +243,7 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
           break;
         }
       } else if (strcmp(atts[i], "href") == 0) {
-        textHref = self->baseContentPath + atts[i + 1];
+        textHref = FsHelpers::normalisePath(self->baseContentPath + atts[i + 1]);
       }
     }
     if ((type == "text" || (type == "start" && !self->textReferenceHref.empty())) && (textHref.length() > 0)) {

lib/Epub/Epub/parsers/TocNavParser.cpp

@@ -1,5 +1,6 @@
 #include "TocNavParser.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
 
 #include "../BookMetadataCache.h"
@@ -140,7 +141,7 @@ void XMLCALL TocNavParser::endElement(void* userData, const XML_Char* name) {
   if (strcmp(name, "a") == 0 && self->state == IN_ANCHOR) {
     // Create TOC entry when closing anchor tag (we have all data now)
     if (!self->currentLabel.empty() && !self->currentHref.empty()) {
-      std::string href = self->baseContentPath + self->currentHref;
+      std::string href = FsHelpers::normalisePath(self->baseContentPath + self->currentHref);
       std::string anchor;
 
       const size_t pos = href.find('#');

lib/Epub/Epub/parsers/TocNcxParser.cpp

@@ -1,5 +1,6 @@
 #include "TocNcxParser.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
 
 #include "../BookMetadataCache.h"
@@ -159,7 +160,7 @@ void XMLCALL TocNcxParser::endElement(void* userData, const XML_Char* name) {
     // This is the safest place to push the data, assuming <navLabel> always comes before <content>.
     // NCX spec says navLabel comes before content.
     if (!self->currentLabel.empty() && !self->currentSrc.empty()) {
-      std::string href = self->baseContentPath + self->currentSrc;
+      std::string href = FsHelpers::normalisePath(self->baseContentPath + self->currentSrc);
       std::string anchor;
 
       const size_t pos = href.find('#');

lib/GfxRenderer/Bitmap.cpp

@@ -8,119 +8,15 @@
 // ============================================================================
 // Note: For cover images, dithering is done in JpegToBmpConverter.cpp
 // This file handles BMP reading - use simple quantization to avoid double-dithering
-constexpr bool USE_FLOYD_STEINBERG = false;  // Disabled - dithering done at JPEG conversion
+constexpr bool USE_ATKINSON = true;  // Use Atkinson dithering instead of Floyd-Steinberg
-constexpr bool USE_NOISE_DITHERING = false;  // Hash-based noise dithering
-// Brightness adjustments:
-constexpr bool USE_BRIGHTNESS = false;    // true: apply brightness/gamma adjustments
-constexpr int BRIGHTNESS_BOOST = 20;      // Brightness offset (0-50), only if USE_BRIGHTNESS=true
-constexpr bool GAMMA_CORRECTION = false;  // Gamma curve, only if USE_BRIGHTNESS=true
 // ============================================================================
 
-// Integer approximation of gamma correction (brightens midtones)
-static inline int applyGamma(int gray) {
-  if (!GAMMA_CORRECTION) return gray;
-  const int product = gray * 255;
-  int x = gray;
-  if (x > 0) {
-    x = (x + product / x) >> 1;
-    x = (x + product / x) >> 1;
-  }
-  return x > 255 ? 255 : x;
-}
-
-// Simple quantization without dithering - just divide into 4 levels
-static inline uint8_t quantizeSimple(int gray) {
-  if (USE_BRIGHTNESS) {
-    gray += BRIGHTNESS_BOOST;
-    if (gray > 255) gray = 255;
-    gray = applyGamma(gray);
-  }
-  return static_cast<uint8_t>(gray >> 6);
-}
-
-// Hash-based noise dithering - survives downsampling without moiré artifacts
-static inline uint8_t quantizeNoise(int gray, int x, int y) {
-  if (USE_BRIGHTNESS) {
-    gray += BRIGHTNESS_BOOST;
-    if (gray > 255) gray = 255;
-    gray = applyGamma(gray);
-  }
-
-  uint32_t hash = static_cast<uint32_t>(x) * 374761393u + static_cast<uint32_t>(y) * 668265263u;
-  hash = (hash ^ (hash >> 13)) * 1274126177u;
-  const int threshold = static_cast<int>(hash >> 24);
-
-  const int scaled = gray * 3;
-  if (scaled < 255) {
-    return (scaled + threshold >= 255) ? 1 : 0;
-  } else if (scaled < 510) {
-    return ((scaled - 255) + threshold >= 255) ? 2 : 1;
-  } else {
-    return ((scaled - 510) + threshold >= 255) ? 3 : 2;
-  }
-}
-
-// Main quantization function
-static inline uint8_t quantize(int gray, int x, int y) {
-  if (USE_NOISE_DITHERING) {
-    return quantizeNoise(gray, x, y);
-  } else {
-    return quantizeSimple(gray);
-  }
-}
-
-// Floyd-Steinberg quantization with error diffusion and serpentine scanning
-// Returns 2-bit value (0-3) and updates error buffers
-static inline uint8_t quantizeFloydSteinberg(int gray, int x, int width, int16_t* errorCurRow, int16_t* errorNextRow,
-                                             bool reverseDir) {
-  // Add accumulated error to this pixel
-  int adjusted = gray + errorCurRow[x + 1];
-
-  // Clamp to valid range
-  if (adjusted < 0) adjusted = 0;
-  if (adjusted > 255) adjusted = 255;
-
-  // Quantize to 4 levels (0, 85, 170, 255)
-  uint8_t quantized;
-  int quantizedValue;
-  if (adjusted < 43) {
-    quantized = 0;
-    quantizedValue = 0;
-  } else if (adjusted < 128) {
-    quantized = 1;
-    quantizedValue = 85;
-  } else if (adjusted < 213) {
-    quantized = 2;
-    quantizedValue = 170;
-  } else {
-    quantized = 3;
-    quantizedValue = 255;
-  }
-
-  // Calculate error
-  int error = adjusted - quantizedValue;
-
-  // Distribute error to neighbors (serpentine: direction-aware)
-  if (!reverseDir) {
-    // Left to right
-    errorCurRow[x + 2] += (error * 7) >> 4;   // Right: 7/16
-    errorNextRow[x] += (error * 3) >> 4;      // Bottom-left: 3/16
-    errorNextRow[x + 1] += (error * 5) >> 4;  // Bottom: 5/16
-    errorNextRow[x + 2] += (error) >> 4;      // Bottom-right: 1/16
-  } else {
-    // Right to left (mirrored)
-    errorCurRow[x] += (error * 7) >> 4;       // Left: 7/16
-    errorNextRow[x + 2] += (error * 3) >> 4;  // Bottom-right: 3/16
-    errorNextRow[x + 1] += (error * 5) >> 4;  // Bottom: 5/16
-    errorNextRow[x] += (error) >> 4;          // Bottom-left: 1/16
-  }
-
-  return quantized;
-}
-
 Bitmap::~Bitmap() {
   delete[] errorCurRow;
   delete[] errorNextRow;
+
+  delete atkinsonDitherer;
+  delete fsDitherer;
 }
 
 uint16_t Bitmap::readLE16(FsFile& f) {
@@ -244,13 +140,14 @@ BmpReaderError Bitmap::parseHeaders() {
     return BmpReaderError::SeekPixelDataFailed;
   }
 
-  // Allocate Floyd-Steinberg error buffers if enabled
+  // Create ditherer if enabled (only for 2-bit output)
-  if (USE_FLOYD_STEINBERG) {
+  // Use OUTPUT dimensions for dithering (after prescaling)
-    delete[] errorCurRow;
+  if (bpp > 2 && dithering) {
-    delete[] errorNextRow;
+    if (USE_ATKINSON) {
-    errorCurRow = new int16_t[width + 2]();  // +2 for boundary handling
+      atkinsonDitherer = new AtkinsonDitherer(width);
-    errorNextRow = new int16_t[width + 2]();
+    } else {
-    prevRowY = -1;
+      fsDitherer = new FloydSteinbergDitherer(width);
+    }
   }
 
   return BmpReaderError::Ok;
@@ -261,17 +158,6 @@ BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
   // Note: rowBuffer should be pre-allocated by the caller to size 'rowBytes'
   if (file.read(rowBuffer, rowBytes) != rowBytes) return BmpReaderError::ShortReadRow;
 
-  // Handle Floyd-Steinberg error buffer progression
-  const bool useFS = USE_FLOYD_STEINBERG && errorCurRow && errorNextRow;
-  if (useFS) {
-    if (prevRowY != -1) {
-      // Sequential access - swap buffers
-      int16_t* temp = errorCurRow;
-      errorCurRow = errorNextRow;
-      errorNextRow = temp;
-      memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    }
-  }
   prevRowY += 1;
 
   uint8_t* outPtr = data;
@@ -282,12 +168,18 @@ BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
   // Helper lambda to pack 2bpp color into the output stream
   auto packPixel = [&](const uint8_t lum) {
     uint8_t color;
-    if (useFS) {
+    if (atkinsonDitherer) {
-      // Floyd-Steinberg error diffusion
+      color = atkinsonDitherer->processPixel(adjustPixel(lum), currentX);
-      color = quantizeFloydSteinberg(lum, currentX, width, errorCurRow, errorNextRow, false);
+    } else if (fsDitherer) {
+      color = fsDitherer->processPixel(adjustPixel(lum), currentX);
     } else {
-      // Simple quantization or noise dithering
+      if (bpp > 2) {
-      color = quantize(lum, currentX, prevRowY);
+        // Simple quantization or noise dithering
+        color = quantize(adjustPixel(lum), currentX, prevRowY);
+      } else {
+        // do not quantize 2bpp image
+        color = static_cast<uint8_t>(lum >> 6);
+      }
     }
     currentOutByte |= (color << bitShift);
     if (bitShift == 0) {
@@ -345,6 +237,11 @@ BmpReaderError Bitmap::readNextRow(uint8_t* data, uint8_t* rowBuffer) const {
       return BmpReaderError::UnsupportedBpp;
   }
 
+  if (atkinsonDitherer)
+    atkinsonDitherer->nextRow();
+  else if (fsDitherer)
+    fsDitherer->nextRow();
+
   // Flush remaining bits if width is not a multiple of 4
   if (bitShift != 6) *outPtr = currentOutByte;
 
@@ -356,12 +253,9 @@ BmpReaderError Bitmap::rewindToData() const {
     return BmpReaderError::SeekPixelDataFailed;
   }
 
-  // Reset Floyd-Steinberg error buffers when rewinding
+  // Reset dithering when rewinding
-  if (USE_FLOYD_STEINBERG && errorCurRow && errorNextRow) {
+  if (fsDitherer) fsDitherer->reset();
-    memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
+  if (atkinsonDitherer) atkinsonDitherer->reset();
-    memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    prevRowY = -1;
-  }
 
   return BmpReaderError::Ok;
 }

lib/GfxRenderer/Bitmap.h

@@ -2,6 +2,10 @@
 
 #include <SdFat.h>
 
+#include <cstdint>
+
+#include "BitmapHelpers.h"
+
 enum class BmpReaderError : uint8_t {
   Ok = 0,
   FileInvalid,
@@ -28,7 +32,7 @@ class Bitmap {
  public:
   static const char* errorToString(BmpReaderError err);
 
-  explicit Bitmap(FsFile& file) : file(file) {}
+  explicit Bitmap(FsFile& file, bool dithering = false) : file(file), dithering(dithering) {}
   ~Bitmap();
   BmpReaderError parseHeaders();
   BmpReaderError readNextRow(uint8_t* data, uint8_t* rowBuffer) const;
@@ -44,6 +48,7 @@ class Bitmap {
   static uint32_t readLE32(FsFile& f);
 
   FsFile& file;
+  bool dithering = false;
   int width = 0;
   int height = 0;
   bool topDown = false;
@@ -56,4 +61,7 @@ class Bitmap {
   mutable int16_t* errorCurRow = nullptr;
   mutable int16_t* errorNextRow = nullptr;
   mutable int prevRowY = -1;  // Track row progression for error propagation
+
+  mutable AtkinsonDitherer* atkinsonDitherer = nullptr;
+  mutable FloydSteinbergDitherer* fsDitherer = nullptr;
 };

lib/GfxRenderer/BitmapHelpers.cpp

@@ -0,0 +1,90 @@
+#include "BitmapHelpers.h"
+
+#include <cstdint>
+
+// Brightness/Contrast adjustments:
+constexpr bool USE_BRIGHTNESS = false;       // true: apply brightness/gamma adjustments
+constexpr int BRIGHTNESS_BOOST = 10;         // Brightness offset (0-50)
+constexpr bool GAMMA_CORRECTION = false;     // Gamma curve (brightens midtones)
+constexpr float CONTRAST_FACTOR = 1.15f;     // Contrast multiplier (1.0 = no change, >1 = more contrast)
+constexpr bool USE_NOISE_DITHERING = false;  // Hash-based noise dithering
+
+// Integer approximation of gamma correction (brightens midtones)
+// Uses a simple curve: out = 255 * sqrt(in/255) ≈ sqrt(in * 255)
+static inline int applyGamma(int gray) {
+  if (!GAMMA_CORRECTION) return gray;
+  // Fast integer square root approximation for gamma ~0.5 (brightening)
+  // This brightens dark/mid tones while preserving highlights
+  const int product = gray * 255;
+  // Newton-Raphson integer sqrt (2 iterations for good accuracy)
+  int x = gray;
+  if (x > 0) {
+    x = (x + product / x) >> 1;
+    x = (x + product / x) >> 1;
+  }
+  return x > 255 ? 255 : x;
+}
+
+// Apply contrast adjustment around midpoint (128)
+// factor > 1.0 increases contrast, < 1.0 decreases
+static inline int applyContrast(int gray) {
+  // Integer-based contrast: (gray - 128) * factor + 128
+  // Using fixed-point: factor 1.15 ≈ 115/100
+  constexpr int factorNum = static_cast<int>(CONTRAST_FACTOR * 100);
+  int adjusted = ((gray - 128) * factorNum) / 100 + 128;
+  if (adjusted < 0) adjusted = 0;
+  if (adjusted > 255) adjusted = 255;
+  return adjusted;
+}
+// Combined brightness/contrast/gamma adjustment
+int adjustPixel(int gray) {
+  if (!USE_BRIGHTNESS) return gray;
+
+  // Order: contrast first, then brightness, then gamma
+  gray = applyContrast(gray);
+  gray += BRIGHTNESS_BOOST;
+  if (gray > 255) gray = 255;
+  if (gray < 0) gray = 0;
+  gray = applyGamma(gray);
+
+  return gray;
+}
+// Simple quantization without dithering - divide into 4 levels
+// The thresholds are fine-tuned to the X4 display
+uint8_t quantizeSimple(int gray) {
+  if (gray < 45) {
+    return 0;
+  } else if (gray < 70) {
+    return 1;
+  } else if (gray < 140) {
+    return 2;
+  } else {
+    return 3;
+  }
+}
+
+// Hash-based noise dithering - survives downsampling without moiré artifacts
+// Uses integer hash to generate pseudo-random threshold per pixel
+static inline uint8_t quantizeNoise(int gray, int x, int y) {
+  uint32_t hash = static_cast<uint32_t>(x) * 374761393u + static_cast<uint32_t>(y) * 668265263u;
+  hash = (hash ^ (hash >> 13)) * 1274126177u;
+  const int threshold = static_cast<int>(hash >> 24);
+
+  const int scaled = gray * 3;
+  if (scaled < 255) {
+    return (scaled + threshold >= 255) ? 1 : 0;
+  } else if (scaled < 510) {
+    return ((scaled - 255) + threshold >= 255) ? 2 : 1;
+  } else {
+    return ((scaled - 510) + threshold >= 255) ? 3 : 2;
+  }
+}
+
+// Main quantization function - selects between methods based on config
+uint8_t quantize(int gray, int x, int y) {
+  if (USE_NOISE_DITHERING) {
+    return quantizeNoise(gray, x, y);
+  } else {
+    return quantizeSimple(gray);
+  }
+}

lib/GfxRenderer/BitmapHelpers.h

@@ -0,0 +1,233 @@
+#pragma once
+
+#include <cstring>
+
+// Helper functions
+uint8_t quantize(int gray, int x, int y);
+uint8_t quantizeSimple(int gray);
+int adjustPixel(int gray);
+
+// Atkinson dithering - distributes only 6/8 (75%) of error for cleaner results
+// Error distribution pattern:
+//     X  1/8 1/8
+// 1/8 1/8 1/8
+//     1/8
+// Less error buildup = fewer artifacts than Floyd-Steinberg
+class AtkinsonDitherer {
+ public:
+  explicit AtkinsonDitherer(int width) : width(width) {
+    errorRow0 = new int16_t[width + 4]();  // Current row
+    errorRow1 = new int16_t[width + 4]();  // Next row
+    errorRow2 = new int16_t[width + 4]();  // Row after next
+  }
+
+  ~AtkinsonDitherer() {
+    delete[] errorRow0;
+    delete[] errorRow1;
+    delete[] errorRow2;
+  }
+  // **1. EXPLICITLY DELETE THE COPY CONSTRUCTOR**
+  AtkinsonDitherer(const AtkinsonDitherer& other) = delete;
+
+  // **2. EXPLICITLY DELETE THE COPY ASSIGNMENT OPERATOR**
+  AtkinsonDitherer& operator=(const AtkinsonDitherer& other) = delete;
+
+  uint8_t processPixel(int gray, int x) {
+    // Add accumulated error
+    int adjusted = gray + errorRow0[x + 2];
+    if (adjusted < 0) adjusted = 0;
+    if (adjusted > 255) adjusted = 255;
+
+    // Quantize to 4 levels
+    uint8_t quantized;
+    int quantizedValue;
+    if (false) {  // original thresholds
+      if (adjusted < 43) {
+        quantized = 0;
+        quantizedValue = 0;
+      } else if (adjusted < 128) {
+        quantized = 1;
+        quantizedValue = 85;
+      } else if (adjusted < 213) {
+        quantized = 2;
+        quantizedValue = 170;
+      } else {
+        quantized = 3;
+        quantizedValue = 255;
+      }
+    } else {  // fine-tuned to X4 eink display
+      if (adjusted < 30) {
+        quantized = 0;
+        quantizedValue = 15;
+      } else if (adjusted < 50) {
+        quantized = 1;
+        quantizedValue = 30;
+      } else if (adjusted < 140) {
+        quantized = 2;
+        quantizedValue = 80;
+      } else {
+        quantized = 3;
+        quantizedValue = 210;
+      }
+    }
+
+    // Calculate error (only distribute 6/8 = 75%)
+    int error = (adjusted - quantizedValue) >> 3;  // error/8
+
+    // Distribute 1/8 to each of 6 neighbors
+    errorRow0[x + 3] += error;  // Right
+    errorRow0[x + 4] += error;  // Right+1
+    errorRow1[x + 1] += error;  // Bottom-left
+    errorRow1[x + 2] += error;  // Bottom
+    errorRow1[x + 3] += error;  // Bottom-right
+    errorRow2[x + 2] += error;  // Two rows down
+
+    return quantized;
+  }
+
+  void nextRow() {
+    int16_t* temp = errorRow0;
+    errorRow0 = errorRow1;
+    errorRow1 = errorRow2;
+    errorRow2 = temp;
+    memset(errorRow2, 0, (width + 4) * sizeof(int16_t));
+  }
+
+  void reset() {
+    memset(errorRow0, 0, (width + 4) * sizeof(int16_t));
+    memset(errorRow1, 0, (width + 4) * sizeof(int16_t));
+    memset(errorRow2, 0, (width + 4) * sizeof(int16_t));
+  }
+
+ private:
+  int width;
+  int16_t* errorRow0;
+  int16_t* errorRow1;
+  int16_t* errorRow2;
+};
+
+// Floyd-Steinberg error diffusion dithering with serpentine scanning
+// Serpentine scanning alternates direction each row to reduce "worm" artifacts
+// Error distribution pattern (left-to-right):
+//       X   7/16
+// 3/16 5/16 1/16
+// Error distribution pattern (right-to-left, mirrored):
+// 1/16 5/16 3/16
+//      7/16  X
+class FloydSteinbergDitherer {
+ public:
+  explicit FloydSteinbergDitherer(int width) : width(width), rowCount(0) {
+    errorCurRow = new int16_t[width + 2]();  // +2 for boundary handling
+    errorNextRow = new int16_t[width + 2]();
+  }
+
+  ~FloydSteinbergDitherer() {
+    delete[] errorCurRow;
+    delete[] errorNextRow;
+  }
+
+  // **1. EXPLICITLY DELETE THE COPY CONSTRUCTOR**
+  FloydSteinbergDitherer(const FloydSteinbergDitherer& other) = delete;
+
+  // **2. EXPLICITLY DELETE THE COPY ASSIGNMENT OPERATOR**
+  FloydSteinbergDitherer& operator=(const FloydSteinbergDitherer& other) = delete;
+
+  // Process a single pixel and return quantized 2-bit value
+  // x is the logical x position (0 to width-1), direction handled internally
+  uint8_t processPixel(int gray, int x) {
+    // Add accumulated error to this pixel
+    int adjusted = gray + errorCurRow[x + 1];
+
+    // Clamp to valid range
+    if (adjusted < 0) adjusted = 0;
+    if (adjusted > 255) adjusted = 255;
+
+    // Quantize to 4 levels (0, 85, 170, 255)
+    uint8_t quantized;
+    int quantizedValue;
+    if (false) {  // original thresholds
+      if (adjusted < 43) {
+        quantized = 0;
+        quantizedValue = 0;
+      } else if (adjusted < 128) {
+        quantized = 1;
+        quantizedValue = 85;
+      } else if (adjusted < 213) {
+        quantized = 2;
+        quantizedValue = 170;
+      } else {
+        quantized = 3;
+        quantizedValue = 255;
+      }
+    } else {  // fine-tuned to X4 eink display
+      if (adjusted < 30) {
+        quantized = 0;
+        quantizedValue = 15;
+      } else if (adjusted < 50) {
+        quantized = 1;
+        quantizedValue = 30;
+      } else if (adjusted < 140) {
+        quantized = 2;
+        quantizedValue = 80;
+      } else {
+        quantized = 3;
+        quantizedValue = 210;
+      }
+    }
+
+    // Calculate error
+    int error = adjusted - quantizedValue;
+
+    // Distribute error to neighbors (serpentine: direction-aware)
+    if (!isReverseRow()) {
+      // Left to right: standard distribution
+      // Right: 7/16
+      errorCurRow[x + 2] += (error * 7) >> 4;
+      // Bottom-left: 3/16
+      errorNextRow[x] += (error * 3) >> 4;
+      // Bottom: 5/16
+      errorNextRow[x + 1] += (error * 5) >> 4;
+      // Bottom-right: 1/16
+      errorNextRow[x + 2] += (error) >> 4;
+    } else {
+      // Right to left: mirrored distribution
+      // Left: 7/16
+      errorCurRow[x] += (error * 7) >> 4;
+      // Bottom-right: 3/16
+      errorNextRow[x + 2] += (error * 3) >> 4;
+      // Bottom: 5/16
+      errorNextRow[x + 1] += (error * 5) >> 4;
+      // Bottom-left: 1/16
+      errorNextRow[x] += (error) >> 4;
+    }
+
+    return quantized;
+  }
+
+  // Call at the end of each row to swap buffers
+  void nextRow() {
+    // Swap buffers
+    int16_t* temp = errorCurRow;
+    errorCurRow = errorNextRow;
+    errorNextRow = temp;
+    // Clear the next row buffer
+    memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
+    rowCount++;
+  }
+
+  // Check if current row should be processed in reverse
+  bool isReverseRow() const { return (rowCount & 1) != 0; }
+
+  // Reset for a new image or MCU block
+  void reset() {
+    memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
+    memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
+    rowCount = 0;
+  }
+
+ private:
+  int width;
+  int rowCount;
+  int16_t* errorCurRow;
+  int16_t* errorNextRow;
+};

lib/JpegToBmpConverter/JpegToBmpConverter.cpp

@@ -7,6 +7,8 @@
 #include <cstdio>
 #include <cstring>
 
+#include "BitmapHelpers.h"
+
 // Context structure for picojpeg callback
 struct JpegReadContext {
   FsFile& file;
@@ -23,282 +25,12 @@ constexpr bool USE_8BIT_OUTPUT = false;  // true: 8-bit grayscale (no quantizati
 constexpr bool USE_ATKINSON = true;          // Atkinson dithering (cleaner than F-S, less error diffusion)
 constexpr bool USE_FLOYD_STEINBERG = false;  // Floyd-Steinberg error diffusion (can cause "worm" artifacts)
 constexpr bool USE_NOISE_DITHERING = false;  // Hash-based noise dithering (good for downsampling)
-// Brightness/Contrast adjustments:
-constexpr bool USE_BRIGHTNESS = true;     // true: apply brightness/gamma adjustments
-constexpr int BRIGHTNESS_BOOST = 10;      // Brightness offset (0-50)
-constexpr bool GAMMA_CORRECTION = true;   // Gamma curve (brightens midtones)
-constexpr float CONTRAST_FACTOR = 1.15f;  // Contrast multiplier (1.0 = no change, >1 = more contrast)
 // Pre-resize to target display size (CRITICAL: avoids dithering artifacts from post-downsampling)
 constexpr bool USE_PRESCALE = true;     // true: scale image to target size before dithering
 constexpr int TARGET_MAX_WIDTH = 480;   // Max width for cover images (portrait display width)
 constexpr int TARGET_MAX_HEIGHT = 800;  // Max height for cover images (portrait display height)
 // ============================================================================
 
-// Integer approximation of gamma correction (brightens midtones)
-// Uses a simple curve: out = 255 * sqrt(in/255) ≈ sqrt(in * 255)
-static inline int applyGamma(int gray) {
-  if (!GAMMA_CORRECTION) return gray;
-  // Fast integer square root approximation for gamma ~0.5 (brightening)
-  // This brightens dark/mid tones while preserving highlights
-  const int product = gray * 255;
-  // Newton-Raphson integer sqrt (2 iterations for good accuracy)
-  int x = gray;
-  if (x > 0) {
-    x = (x + product / x) >> 1;
-    x = (x + product / x) >> 1;
-  }
-  return x > 255 ? 255 : x;
-}
-
-// Apply contrast adjustment around midpoint (128)
-// factor > 1.0 increases contrast, < 1.0 decreases
-static inline int applyContrast(int gray) {
-  // Integer-based contrast: (gray - 128) * factor + 128
-  // Using fixed-point: factor 1.15 ≈ 115/100
-  constexpr int factorNum = static_cast<int>(CONTRAST_FACTOR * 100);
-  int adjusted = ((gray - 128) * factorNum) / 100 + 128;
-  if (adjusted < 0) adjusted = 0;
-  if (adjusted > 255) adjusted = 255;
-  return adjusted;
-}
-
-// Combined brightness/contrast/gamma adjustment
-static inline int adjustPixel(int gray) {
-  if (!USE_BRIGHTNESS) return gray;
-
-  // Order: contrast first, then brightness, then gamma
-  gray = applyContrast(gray);
-  gray += BRIGHTNESS_BOOST;
-  if (gray > 255) gray = 255;
-  if (gray < 0) gray = 0;
-  gray = applyGamma(gray);
-
-  return gray;
-}
-
-// Simple quantization without dithering - just divide into 4 levels
-static inline uint8_t quantizeSimple(int gray) {
-  gray = adjustPixel(gray);
-  // Simple 2-bit quantization: 0-63=0, 64-127=1, 128-191=2, 192-255=3
-  return static_cast<uint8_t>(gray >> 6);
-}
-
-// Hash-based noise dithering - survives downsampling without moiré artifacts
-// Uses integer hash to generate pseudo-random threshold per pixel
-static inline uint8_t quantizeNoise(int gray, int x, int y) {
-  gray = adjustPixel(gray);
-
-  // Generate noise threshold using integer hash (no regular pattern to alias)
-  uint32_t hash = static_cast<uint32_t>(x) * 374761393u + static_cast<uint32_t>(y) * 668265263u;
-  hash = (hash ^ (hash >> 13)) * 1274126177u;
-  const int threshold = static_cast<int>(hash >> 24);  // 0-255
-
-  // Map gray (0-255) to 4 levels with dithering
-  const int scaled = gray * 3;
-
-  if (scaled < 255) {
-    return (scaled + threshold >= 255) ? 1 : 0;
-  } else if (scaled < 510) {
-    return ((scaled - 255) + threshold >= 255) ? 2 : 1;
-  } else {
-    return ((scaled - 510) + threshold >= 255) ? 3 : 2;
-  }
-}
-
-// Main quantization function - selects between methods based on config
-static inline uint8_t quantize(int gray, int x, int y) {
-  if (USE_NOISE_DITHERING) {
-    return quantizeNoise(gray, x, y);
-  } else {
-    return quantizeSimple(gray);
-  }
-}
-
-// Atkinson dithering - distributes only 6/8 (75%) of error for cleaner results
-// Error distribution pattern:
-//     X  1/8 1/8
-// 1/8 1/8 1/8
-//     1/8
-// Less error buildup = fewer artifacts than Floyd-Steinberg
-class AtkinsonDitherer {
- public:
-  AtkinsonDitherer(int width) : width(width) {
-    errorRow0 = new int16_t[width + 4]();  // Current row
-    errorRow1 = new int16_t[width + 4]();  // Next row
-    errorRow2 = new int16_t[width + 4]();  // Row after next
-  }
-
-  ~AtkinsonDitherer() {
-    delete[] errorRow0;
-    delete[] errorRow1;
-    delete[] errorRow2;
-  }
-
-  uint8_t processPixel(int gray, int x) {
-    // Apply brightness/contrast/gamma adjustments
-    gray = adjustPixel(gray);
-
-    // Add accumulated error
-    int adjusted = gray + errorRow0[x + 2];
-    if (adjusted < 0) adjusted = 0;
-    if (adjusted > 255) adjusted = 255;
-
-    // Quantize to 4 levels
-    uint8_t quantized;
-    int quantizedValue;
-    if (adjusted < 43) {
-      quantized = 0;
-      quantizedValue = 0;
-    } else if (adjusted < 128) {
-      quantized = 1;
-      quantizedValue = 85;
-    } else if (adjusted < 213) {
-      quantized = 2;
-      quantizedValue = 170;
-    } else {
-      quantized = 3;
-      quantizedValue = 255;
-    }
-
-    // Calculate error (only distribute 6/8 = 75%)
-    int error = (adjusted - quantizedValue) >> 3;  // error/8
-
-    // Distribute 1/8 to each of 6 neighbors
-    errorRow0[x + 3] += error;  // Right
-    errorRow0[x + 4] += error;  // Right+1
-    errorRow1[x + 1] += error;  // Bottom-left
-    errorRow1[x + 2] += error;  // Bottom
-    errorRow1[x + 3] += error;  // Bottom-right
-    errorRow2[x + 2] += error;  // Two rows down
-
-    return quantized;
-  }
-
-  void nextRow() {
-    int16_t* temp = errorRow0;
-    errorRow0 = errorRow1;
-    errorRow1 = errorRow2;
-    errorRow2 = temp;
-    memset(errorRow2, 0, (width + 4) * sizeof(int16_t));
-  }
-
-  void reset() {
-    memset(errorRow0, 0, (width + 4) * sizeof(int16_t));
-    memset(errorRow1, 0, (width + 4) * sizeof(int16_t));
-    memset(errorRow2, 0, (width + 4) * sizeof(int16_t));
-  }
-
- private:
-  int width;
-  int16_t* errorRow0;
-  int16_t* errorRow1;
-  int16_t* errorRow2;
-};
-
-// Floyd-Steinberg error diffusion dithering with serpentine scanning
-// Serpentine scanning alternates direction each row to reduce "worm" artifacts
-// Error distribution pattern (left-to-right):
-//       X   7/16
-// 3/16 5/16 1/16
-// Error distribution pattern (right-to-left, mirrored):
-// 1/16 5/16 3/16
-//      7/16  X
-class FloydSteinbergDitherer {
- public:
-  FloydSteinbergDitherer(int width) : width(width), rowCount(0) {
-    errorCurRow = new int16_t[width + 2]();  // +2 for boundary handling
-    errorNextRow = new int16_t[width + 2]();
-  }
-
-  ~FloydSteinbergDitherer() {
-    delete[] errorCurRow;
-    delete[] errorNextRow;
-  }
-
-  // Process a single pixel and return quantized 2-bit value
-  // x is the logical x position (0 to width-1), direction handled internally
-  uint8_t processPixel(int gray, int x, bool reverseDirection) {
-    // Add accumulated error to this pixel
-    int adjusted = gray + errorCurRow[x + 1];
-
-    // Clamp to valid range
-    if (adjusted < 0) adjusted = 0;
-    if (adjusted > 255) adjusted = 255;
-
-    // Quantize to 4 levels (0, 85, 170, 255)
-    uint8_t quantized;
-    int quantizedValue;
-    if (adjusted < 43) {
-      quantized = 0;
-      quantizedValue = 0;
-    } else if (adjusted < 128) {
-      quantized = 1;
-      quantizedValue = 85;
-    } else if (adjusted < 213) {
-      quantized = 2;
-      quantizedValue = 170;
-    } else {
-      quantized = 3;
-      quantizedValue = 255;
-    }
-
-    // Calculate error
-    int error = adjusted - quantizedValue;
-
-    // Distribute error to neighbors (serpentine: direction-aware)
-    if (!reverseDirection) {
-      // Left to right: standard distribution
-      // Right: 7/16
-      errorCurRow[x + 2] += (error * 7) >> 4;
-      // Bottom-left: 3/16
-      errorNextRow[x] += (error * 3) >> 4;
-      // Bottom: 5/16
-      errorNextRow[x + 1] += (error * 5) >> 4;
-      // Bottom-right: 1/16
-      errorNextRow[x + 2] += (error) >> 4;
-    } else {
-      // Right to left: mirrored distribution
-      // Left: 7/16
-      errorCurRow[x] += (error * 7) >> 4;
-      // Bottom-right: 3/16
-      errorNextRow[x + 2] += (error * 3) >> 4;
-      // Bottom: 5/16
-      errorNextRow[x + 1] += (error * 5) >> 4;
-      // Bottom-left: 1/16
-      errorNextRow[x] += (error) >> 4;
-    }
-
-    return quantized;
-  }
-
-  // Call at the end of each row to swap buffers
-  void nextRow() {
-    // Swap buffers
-    int16_t* temp = errorCurRow;
-    errorCurRow = errorNextRow;
-    errorNextRow = temp;
-    // Clear the next row buffer
-    memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    rowCount++;
-  }
-
-  // Check if current row should be processed in reverse
-  bool isReverseRow() const { return (rowCount & 1) != 0; }
-
-  // Reset for a new image or MCU block
-  void reset() {
-    memset(errorCurRow, 0, (width + 2) * sizeof(int16_t));
-    memset(errorNextRow, 0, (width + 2) * sizeof(int16_t));
-    rowCount = 0;
-  }
-
- private:
-  int width;
-  int rowCount;
-  int16_t* errorCurRow;
-  int16_t* errorNextRow;
-};
-
 inline void write16(Print& out, const uint16_t value) {
   out.write(value & 0xFF);
   out.write((value >> 8) & 0xFF);
@@ -623,12 +355,12 @@ bool JpegToBmpConverter::jpegFileToBmpStream(FsFile& jpegFile, Print& bmpOut) {
           }
         } else {
           for (int x = 0; x < outWidth; x++) {
-            const uint8_t gray = mcuRowBuffer[bufferY * imageInfo.m_width + x];
+            const uint8_t gray = adjustPixel(mcuRowBuffer[bufferY * imageInfo.m_width + x]);
             uint8_t twoBit;
             if (atkinsonDitherer) {
               twoBit = atkinsonDitherer->processPixel(gray, x);
             } else if (fsDitherer) {
-              twoBit = fsDitherer->processPixel(gray, x, fsDitherer->isReverseRow());
+              twoBit = fsDitherer->processPixel(gray, x);
             } else {
               twoBit = quantize(gray, x, y);
             }
@@ -686,12 +418,12 @@ bool JpegToBmpConverter::jpegFileToBmpStream(FsFile& jpegFile, Print& bmpOut) {
             }
           } else {
             for (int x = 0; x < outWidth; x++) {
-              const uint8_t gray = (rowCount[x] > 0) ? (rowAccum[x] / rowCount[x]) : 0;
+              const uint8_t gray = adjustPixel((rowCount[x] > 0) ? (rowAccum[x] / rowCount[x]) : 0);
               uint8_t twoBit;
               if (atkinsonDitherer) {
                 twoBit = atkinsonDitherer->processPixel(gray, x);
               } else if (fsDitherer) {
-                twoBit = fsDitherer->processPixel(gray, x, fsDitherer->isReverseRow());
+                twoBit = fsDitherer->processPixel(gray, x);
               } else {
                 twoBit = quantize(gray, x, currentOutY);
               }

lib/OpdsParser/OpdsParser.cpp

@@ -0,0 +1,219 @@
+#include "OpdsParser.h"
+
+#include <HardwareSerial.h>
+
+#include <cstring>
+
+OpdsParser::~OpdsParser() {
+  if (parser) {
+    XML_StopParser(parser, XML_FALSE);
+    XML_SetElementHandler(parser, nullptr, nullptr);
+    XML_SetCharacterDataHandler(parser, nullptr);
+    XML_ParserFree(parser);
+    parser = nullptr;
+  }
+}
+
+bool OpdsParser::parse(const char* xmlData, const size_t length) {
+  clear();
+
+  parser = XML_ParserCreate(nullptr);
+  if (!parser) {
+    Serial.printf("[%lu] [OPDS] Couldn't allocate memory for parser\n", millis());
+    return false;
+  }
+
+  XML_SetUserData(parser, this);
+  XML_SetElementHandler(parser, startElement, endElement);
+  XML_SetCharacterDataHandler(parser, characterData);
+
+  // Parse in chunks to avoid large buffer allocations
+  const char* currentPos = xmlData;
+  size_t remaining = length;
+  constexpr size_t chunkSize = 1024;
+
+  while (remaining > 0) {
+    void* const buf = XML_GetBuffer(parser, chunkSize);
+    if (!buf) {
+      Serial.printf("[%lu] [OPDS] Couldn't allocate memory for buffer\n", millis());
+      XML_ParserFree(parser);
+      parser = nullptr;
+      return false;
+    }
+
+    const size_t toRead = remaining < chunkSize ? remaining : chunkSize;
+    memcpy(buf, currentPos, toRead);
+
+    const bool isFinal = (remaining == toRead);
+    if (XML_ParseBuffer(parser, static_cast<int>(toRead), isFinal) == XML_STATUS_ERROR) {
+      Serial.printf("[%lu] [OPDS] Parse error at line %lu: %s\n", millis(), XML_GetCurrentLineNumber(parser),
+                    XML_ErrorString(XML_GetErrorCode(parser)));
+      XML_ParserFree(parser);
+      parser = nullptr;
+      return false;
+    }
+
+    currentPos += toRead;
+    remaining -= toRead;
+  }
+
+  // Clean up parser
+  XML_ParserFree(parser);
+  parser = nullptr;
+
+  Serial.printf("[%lu] [OPDS] Parsed %zu entries\n", millis(), entries.size());
+  return true;
+}
+
+void OpdsParser::clear() {
+  entries.clear();
+  currentEntry = OpdsEntry{};
+  currentText.clear();
+  inEntry = false;
+  inTitle = false;
+  inAuthor = false;
+  inAuthorName = false;
+  inId = false;
+}
+
+std::vector<OpdsEntry> OpdsParser::getBooks() const {
+  std::vector<OpdsEntry> books;
+  for (const auto& entry : entries) {
+    if (entry.type == OpdsEntryType::BOOK) {
+      books.push_back(entry);
+    }
+  }
+  return books;
+}
+
+const char* OpdsParser::findAttribute(const XML_Char** atts, const char* name) {
+  for (int i = 0; atts[i]; i += 2) {
+    if (strcmp(atts[i], name) == 0) {
+      return atts[i + 1];
+    }
+  }
+  return nullptr;
+}
+
+void XMLCALL OpdsParser::startElement(void* userData, const XML_Char* name, const XML_Char** atts) {
+  auto* self = static_cast<OpdsParser*>(userData);
+
+  // Check for entry element (with or without namespace prefix)
+  if (strcmp(name, "entry") == 0 || strstr(name, ":entry") != nullptr) {
+    self->inEntry = true;
+    self->currentEntry = OpdsEntry{};
+    return;
+  }
+
+  if (!self->inEntry) return;
+
+  // Check for title element
+  if (strcmp(name, "title") == 0 || strstr(name, ":title") != nullptr) {
+    self->inTitle = true;
+    self->currentText.clear();
+    return;
+  }
+
+  // Check for author element
+  if (strcmp(name, "author") == 0 || strstr(name, ":author") != nullptr) {
+    self->inAuthor = true;
+    return;
+  }
+
+  // Check for author name element
+  if (self->inAuthor && (strcmp(name, "name") == 0 || strstr(name, ":name") != nullptr)) {
+    self->inAuthorName = true;
+    self->currentText.clear();
+    return;
+  }
+
+  // Check for id element
+  if (strcmp(name, "id") == 0 || strstr(name, ":id") != nullptr) {
+    self->inId = true;
+    self->currentText.clear();
+    return;
+  }
+
+  // Check for link element
+  if (strcmp(name, "link") == 0 || strstr(name, ":link") != nullptr) {
+    const char* rel = findAttribute(atts, "rel");
+    const char* type = findAttribute(atts, "type");
+    const char* href = findAttribute(atts, "href");
+
+    if (href) {
+      // Check for acquisition link with epub type (this is a downloadable book)
+      if (rel && type && strstr(rel, "opds-spec.org/acquisition") != nullptr &&
+          strcmp(type, "application/epub+zip") == 0) {
+        self->currentEntry.type = OpdsEntryType::BOOK;
+        self->currentEntry.href = href;
+      }
+      // Check for navigation link (subsection or no rel specified with atom+xml type)
+      else if (type && strstr(type, "application/atom+xml") != nullptr) {
+        // Only set navigation link if we don't already have an epub link
+        if (self->currentEntry.type != OpdsEntryType::BOOK) {
+          self->currentEntry.type = OpdsEntryType::NAVIGATION;
+          self->currentEntry.href = href;
+        }
+      }
+    }
+  }
+}
+
+void XMLCALL OpdsParser::endElement(void* userData, const XML_Char* name) {
+  auto* self = static_cast<OpdsParser*>(userData);
+
+  // Check for entry end
+  if (strcmp(name, "entry") == 0 || strstr(name, ":entry") != nullptr) {
+    // Only add entry if it has required fields (title and href)
+    if (!self->currentEntry.title.empty() && !self->currentEntry.href.empty()) {
+      self->entries.push_back(self->currentEntry);
+    }
+    self->inEntry = false;
+    self->currentEntry = OpdsEntry{};
+    return;
+  }
+
+  if (!self->inEntry) return;
+
+  // Check for title end
+  if (strcmp(name, "title") == 0 || strstr(name, ":title") != nullptr) {
+    if (self->inTitle) {
+      self->currentEntry.title = self->currentText;
+    }
+    self->inTitle = false;
+    return;
+  }
+
+  // Check for author end
+  if (strcmp(name, "author") == 0 || strstr(name, ":author") != nullptr) {
+    self->inAuthor = false;
+    return;
+  }
+
+  // Check for author name end
+  if (self->inAuthor && (strcmp(name, "name") == 0 || strstr(name, ":name") != nullptr)) {
+    if (self->inAuthorName) {
+      self->currentEntry.author = self->currentText;
+    }
+    self->inAuthorName = false;
+    return;
+  }
+
+  // Check for id end
+  if (strcmp(name, "id") == 0 || strstr(name, ":id") != nullptr) {
+    if (self->inId) {
+      self->currentEntry.id = self->currentText;
+    }
+    self->inId = false;
+    return;
+  }
+}
+
+void XMLCALL OpdsParser::characterData(void* userData, const XML_Char* s, const int len) {
+  auto* self = static_cast<OpdsParser*>(userData);
+
+  // Only accumulate text when in a text element
+  if (self->inTitle || self->inAuthorName || self->inId) {
+    self->currentText.append(s, len);
+  }
+}

lib/OpdsParser/OpdsParser.h

@@ -0,0 +1,99 @@
+#pragma once
+#include <expat.h>
+
+#include <string>
+#include <vector>
+
+/**
+ * Type of OPDS entry.
+ */
+enum class OpdsEntryType {
+  NAVIGATION,  // Link to another catalog
+  BOOK         // Downloadable book
+};
+
+/**
+ * Represents an entry from an OPDS feed (either a navigation link or a book).
+ */
+struct OpdsEntry {
+  OpdsEntryType type = OpdsEntryType::NAVIGATION;
+  std::string title;
+  std::string author;  // Only for books
+  std::string href;    // Navigation URL or epub download URL
+  std::string id;
+};
+
+// Legacy alias for backward compatibility
+using OpdsBook = OpdsEntry;
+
+/**
+ * Parser for OPDS (Open Publication Distribution System) Atom feeds.
+ * Uses the Expat XML parser to parse OPDS catalog entries.
+ *
+ * Usage:
+ *   OpdsParser parser;
+ *   if (parser.parse(xmlData, xmlLength)) {
+ *     for (const auto& entry : parser.getEntries()) {
+ *       if (entry.type == OpdsEntryType::BOOK) {
+ *         // Downloadable book
+ *       } else {
+ *         // Navigation link to another catalog
+ *       }
+ *     }
+ *   }
+ */
+class OpdsParser {
+ public:
+  OpdsParser() = default;
+  ~OpdsParser();
+
+  // Disable copy
+  OpdsParser(const OpdsParser&) = delete;
+  OpdsParser& operator=(const OpdsParser&) = delete;
+
+  /**
+   * Parse an OPDS XML feed.
+   * @param xmlData Pointer to the XML data
+   * @param length Length of the XML data
+   * @return true if parsing succeeded, false on error
+   */
+  bool parse(const char* xmlData, size_t length);
+
+  /**
+   * Get the parsed entries (both navigation and book entries).
+   * @return Vector of OpdsEntry entries
+   */
+  const std::vector<OpdsEntry>& getEntries() const { return entries; }
+
+  /**
+   * Get only book entries (legacy compatibility).
+   * @return Vector of book entries
+   */
+  std::vector<OpdsEntry> getBooks() const;
+
+  /**
+   * Clear all parsed entries.
+   */
+  void clear();
+
+ private:
+  // Expat callbacks
+  static void XMLCALL startElement(void* userData, const XML_Char* name, const XML_Char** atts);
+  static void XMLCALL endElement(void* userData, const XML_Char* name);
+  static void XMLCALL characterData(void* userData, const XML_Char* s, int len);
+
+  // Helper to find attribute value
+  static const char* findAttribute(const XML_Char** atts, const char* name);
+
+  XML_Parser parser = nullptr;
+  std::vector<OpdsEntry> entries;
+  OpdsEntry currentEntry;
+  std::string currentText;
+
+  // Parser state
+  bool inEntry = false;
+  bool inTitle = false;
+  bool inAuthor = false;
+  bool inAuthorName = false;
+  bool inId = false;
+};

platformio.ini

@@ -1,7 +1,9 @@
 [platformio]
-crosspoint_version = 0.12.0
 default_envs = default
 
+[crosspoint]
+version = 0.13.1
+
 [base]
 platform = espressif32 @ 6.12.0
 board = esp32-c3-devkitm-1
@@ -50,10 +52,10 @@ lib_deps =
 extends = base
 build_flags =
   ${base.build_flags}
-  -DCROSSPOINT_VERSION=\"${platformio.crosspoint_version}-dev\"
+  -DCROSSPOINT_VERSION=\"${crosspoint.version}-dev\"
 
 [env:gh_release]
 extends = base
 build_flags =
   ${base.build_flags}
-  -DCROSSPOINT_VERSION=\"${platformio.crosspoint_version}\"
+  -DCROSSPOINT_VERSION=\"${crosspoint.version}\"

src/CrossPointSettings.cpp

@@ -4,6 +4,8 @@
 #include <SDCardManager.h>
 #include <Serialization.h>
 
+#include <cstring>
+
 #include "fontIds.h"
 
 // Initialize the static instance
@@ -12,7 +14,7 @@ CrossPointSettings CrossPointSettings::instance;
 namespace {
 constexpr uint8_t SETTINGS_FILE_VERSION = 1;
 // Increment this when adding new persisted settings fields
-constexpr uint8_t SETTINGS_COUNT = 15;
+constexpr uint8_t SETTINGS_COUNT = 17;
 constexpr char SETTINGS_FILE[] = "/.crosspoint/settings.bin";
 }  // namespace
 
@@ -42,6 +44,9 @@ bool CrossPointSettings::saveToFile() const {
   serialization::writePod(outputFile, refreshFrequency);
   serialization::writePod(outputFile, screenMargin);
   serialization::writePod(outputFile, sleepScreenCoverMode);
+  serialization::writeString(outputFile, std::string(opdsServerUrl));
+  serialization::writePod(outputFile, textAntiAliasing);
+  serialization::writePod(outputFile, hideBatteryPercentage);
   outputFile.close();
 
   Serial.printf("[%lu] [CPS] Settings saved to file\n", millis());
@@ -98,6 +103,16 @@ bool CrossPointSettings::loadFromFile() {
     if (++settingsRead >= fileSettingsCount) break;
     serialization::readPod(inputFile, sleepScreenCoverMode);
     if (++settingsRead >= fileSettingsCount) break;
+    {
+      std::string urlStr;
+      serialization::readString(inputFile, urlStr);
+      strncpy(opdsServerUrl, urlStr.c_str(), sizeof(opdsServerUrl) - 1);
+      opdsServerUrl[sizeof(opdsServerUrl) - 1] = '\0';
+    }
+    serialization::readPod(inputFile, textAntiAliasing);
+    if (++settingsRead >= fileSettingsCount) break;
+    serialization::readPod(inputFile, hideBatteryPercentage);
+    if (++settingsRead >= fileSettingsCount) break;
   } while (false);
 
   inputFile.close();

src/CrossPointSettings.h

@@ -52,6 +52,12 @@ class CrossPointSettings {
   // E-ink refresh frequency (pages between full refreshes)
   enum REFRESH_FREQUENCY { REFRESH_1 = 0, REFRESH_5 = 1, REFRESH_10 = 2, REFRESH_15 = 3, REFRESH_30 = 4 };
 
+  // Short power button press actions
+  enum SHORT_PWRBTN { IGNORE = 0, SLEEP = 1, PAGE_TURN = 2 };
+
+  // Hide battery percentage
+  enum HIDE_BATTERY_PERCENTAGE { HIDE_NEVER = 0, HIDE_READER = 1, HIDE_ALWAYS = 2 };
+
   // Sleep screen settings
   uint8_t sleepScreen = DARK;
   // Sleep screen cover mode settings
@@ -60,8 +66,9 @@ class CrossPointSettings {
   uint8_t statusBar = FULL;
   // Text rendering settings
   uint8_t extraParagraphSpacing = 1;
-  // Duration of the power button press
+  uint8_t textAntiAliasing = 1;
-  uint8_t shortPwrBtn = 0;
+  // Short power button click behaviour
+  uint8_t shortPwrBtn = IGNORE;
   // EPUB reading orientation settings
   // 0 = portrait (default), 1 = landscape clockwise, 2 = inverted, 3 = landscape counter-clockwise
   uint8_t orientation = PORTRAIT;
@@ -77,16 +84,21 @@ class CrossPointSettings {
   uint8_t sleepTimeout = SLEEP_10_MIN;
   // E-ink refresh frequency (default 15 pages)
   uint8_t refreshFrequency = REFRESH_15;
-
   // Reader screen margin settings
   uint8_t screenMargin = 5;
+  // OPDS browser settings
+  char opdsServerUrl[128] = "";
+  // Hide battery percentage
+  uint8_t hideBatteryPercentage = HIDE_NEVER;
 
   ~CrossPointSettings() = default;
 
   // Get singleton instance
   static CrossPointSettings& getInstance() { return instance; }
 
-  uint16_t getPowerButtonDuration() const { return shortPwrBtn ? 10 : 400; }
+  uint16_t getPowerButtonDuration() const {
+    return (shortPwrBtn == CrossPointSettings::SHORT_PWRBTN::SLEEP) ? 10 : 400;
+  }
   int getReaderFontId() const;
 
   bool saveToFile() const;
@@ -95,7 +107,6 @@ class CrossPointSettings {
   float getReaderLineCompression() const;
   unsigned long getSleepTimeoutMs() const;
   int getRefreshFrequency() const;
-  int getReaderScreenMargin() const;
 };
 
 // Helper macro to access settings

src/ScreenComponents.cpp

@@ -2,15 +2,17 @@
 
 #include <GfxRenderer.h>
 
+#include <cstdint>
 #include <string>
 
 #include "Battery.h"
 #include "fontIds.h"
 
-void ScreenComponents::drawBattery(const GfxRenderer& renderer, const int left, const int top) {
+void ScreenComponents::drawBattery(const GfxRenderer& renderer, const int left, const int top,
+                                   const bool showPercentage) {
   // Left aligned battery icon and percentage
   const uint16_t percentage = battery.readPercentage();
-  const auto percentageText = std::to_string(percentage) + "%";
+  const auto percentageText = showPercentage ? std::to_string(percentage) + "%" : "";
   renderer.drawText(SMALL_FONT_ID, left + 20, top, percentageText.c_str());
 
   // 1 column on left, 2 columns on right, 5 columns of battery body
@@ -39,3 +41,26 @@ void ScreenComponents::drawBattery(const GfxRenderer& renderer, const int left,
 
   renderer.fillRect(x + 2, y + 2, filledWidth, batteryHeight - 4);
 }
+
+void ScreenComponents::drawProgressBar(const GfxRenderer& renderer, const int x, const int y, const int width,
+                                       const int height, const size_t current, const size_t total) {
+  if (total == 0) {
+    return;
+  }
+
+  // Use 64-bit arithmetic to avoid overflow for large files
+  const int percent = static_cast<int>((static_cast<uint64_t>(current) * 100) / total);
+
+  // Draw outline
+  renderer.drawRect(x, y, width, height);
+
+  // Draw filled portion
+  const int fillWidth = (width - 4) * percent / 100;
+  if (fillWidth > 0) {
+    renderer.fillRect(x + 2, y + 2, fillWidth, height - 4);
+  }
+
+  // Draw percentage text centered below bar
+  const std::string percentText = std::to_string(percent) + "%";
+  renderer.drawCenteredText(UI_10_FONT_ID, y + height + 15, percentText.c_str());
+}

src/ScreenComponents.h

@@ -1,8 +1,24 @@
 #pragma once
 
+#include <cstddef>
+#include <cstdint>
+
 class GfxRenderer;
 
 class ScreenComponents {
  public:
-  static void drawBattery(const GfxRenderer& renderer, int left, int top);
+  static void drawBattery(const GfxRenderer& renderer, int left, int top, bool showPercentage = true);
+
+  /**
+   * Draw a progress bar with percentage text.
+   * @param renderer The graphics renderer
+   * @param x Left position of the bar
+   * @param y Top position of the bar
+   * @param width Width of the bar
+   * @param height Height of the bar
+   * @param current Current progress value
+   * @param total Total value for 100% progress
+   */
+  static void drawProgressBar(const GfxRenderer& renderer, int x, int y, int width, int height, size_t current,
+                              size_t total);
 };

src/activities/boot_sleep/SleepActivity.cpp

@@ -9,20 +9,7 @@
 #include "CrossPointState.h"
 #include "fontIds.h"
 #include "images/CrossLarge.h"
-
+#include "util/StringUtils.h"
-namespace {
-// Check if path has XTC extension (.xtc or .xtch)
-bool isXtcFile(const std::string& path) {
-  if (path.length() < 4) return false;
-  std::string ext4 = path.substr(path.length() - 4);
-  if (ext4 == ".xtc") return true;
-  if (path.length() >= 5) {
-    std::string ext5 = path.substr(path.length() - 5);
-    if (ext5 == ".xtch") return true;
-  }
-  return false;
-}
-}  // namespace
 
 void SleepActivity::onEnter() {
   Activity::onEnter();
@@ -62,7 +49,7 @@ void SleepActivity::renderCustomSleepScreen() const {
   auto dir = SdMan.open("/sleep");
   if (dir && dir.isDirectory()) {
     std::vector<std::string> files;
-    char name[128];
+    char name[500];
     // collect all valid BMP files
     for (auto file = dir.openNextFile(); file; file = dir.openNextFile()) {
       if (file.isDirectory()) {
@@ -99,7 +86,7 @@ void SleepActivity::renderCustomSleepScreen() const {
       if (SdMan.openFileForRead("SLP", filename, file)) {
         Serial.printf("[%lu] [SLP] Randomly loading: /sleep/%s\n", millis(), files[randomFileIndex].c_str());
         delay(100);
-        Bitmap bitmap(file);
+        Bitmap bitmap(file, true);
         if (bitmap.parseHeaders() == BmpReaderError::Ok) {
           renderBitmapSleepScreen(bitmap);
           dir.close();
@@ -114,7 +101,7 @@ void SleepActivity::renderCustomSleepScreen() const {
   // render a custom sleep screen instead of the default.
   FsFile file;
   if (SdMan.openFileForRead("SLP", "/sleep.bmp", file)) {
-    Bitmap bitmap(file);
+    Bitmap bitmap(file, true);
     if (bitmap.parseHeaders() == BmpReaderError::Ok) {
       Serial.printf("[%lu] [SLP] Loading: /sleep.bmp\n", millis());
       renderBitmapSleepScreen(bitmap);
@@ -212,9 +199,10 @@ void SleepActivity::renderCoverSleepScreen() const {
   }
 
   std::string coverBmpPath;
+  bool cropped = SETTINGS.sleepScreenCoverMode == CrossPointSettings::SLEEP_SCREEN_COVER_MODE::CROP;
 
-  // Check if the current book is XTC or EPUB
+  if (StringUtils::checkFileExtension(APP_STATE.openEpubPath, ".xtc") ||
-  if (isXtcFile(APP_STATE.openEpubPath)) {
+      StringUtils::checkFileExtension(APP_STATE.openEpubPath, ".xtch")) {
     // Handle XTC file
     Xtc lastXtc(APP_STATE.openEpubPath, "/.crosspoint");
     if (!lastXtc.load()) {
@@ -228,7 +216,7 @@ void SleepActivity::renderCoverSleepScreen() const {
     }
 
     coverBmpPath = lastXtc.getCoverBmpPath();
-  } else {
+  } else if (StringUtils::checkFileExtension(APP_STATE.openEpubPath, ".epub")) {
     // Handle EPUB file
     Epub lastEpub(APP_STATE.openEpubPath, "/.crosspoint");
     if (!lastEpub.load()) {
@@ -236,12 +224,14 @@ void SleepActivity::renderCoverSleepScreen() const {
       return renderDefaultSleepScreen();
     }
 
-    if (!lastEpub.generateCoverBmp()) {
+    if (!lastEpub.generateCoverBmp(cropped)) {
       Serial.println("[SLP] Failed to generate cover bmp");
       return renderDefaultSleepScreen();
     }
 
-    coverBmpPath = lastEpub.getCoverBmpPath();
+    coverBmpPath = lastEpub.getCoverBmpPath(cropped);
+  } else {
+    return renderDefaultSleepScreen();
   }
 
   FsFile file;

src/activities/browser/OpdsBookBrowserActivity.cpp

@@ -0,0 +1,408 @@
+#include "OpdsBookBrowserActivity.h"
+
+#include <GfxRenderer.h>
+#include <HardwareSerial.h>
+#include <WiFi.h>
+
+#include "CrossPointSettings.h"
+#include "MappedInputManager.h"
+#include "ScreenComponents.h"
+#include "activities/network/WifiSelectionActivity.h"
+#include "fontIds.h"
+#include "network/HttpDownloader.h"
+#include "util/StringUtils.h"
+#include "util/UrlUtils.h"
+
+namespace {
+constexpr int PAGE_ITEMS = 23;
+constexpr int SKIP_PAGE_MS = 700;
+constexpr char OPDS_ROOT_PATH[] = "opds";  // No leading slash - relative to server URL
+}  // namespace
+
+void OpdsBookBrowserActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<OpdsBookBrowserActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void OpdsBookBrowserActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+
+  renderingMutex = xSemaphoreCreateMutex();
+  state = BrowserState::CHECK_WIFI;
+  entries.clear();
+  navigationHistory.clear();
+  currentPath = OPDS_ROOT_PATH;
+  selectorIndex = 0;
+  errorMessage.clear();
+  statusMessage = "Checking WiFi...";
+  updateRequired = true;
+
+  xTaskCreate(&OpdsBookBrowserActivity::taskTrampoline, "OpdsBookBrowserTask",
+              4096,               // Stack size (larger for HTTP operations)
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+
+  // Check WiFi and connect if needed, then fetch feed
+  checkAndConnectWifi();
+}
+
+void OpdsBookBrowserActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+
+  // Turn off WiFi when exiting
+  WiFi.mode(WIFI_OFF);
+
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+  entries.clear();
+  navigationHistory.clear();
+}
+
+void OpdsBookBrowserActivity::loop() {
+  // Handle WiFi selection subactivity
+  if (state == BrowserState::WIFI_SELECTION) {
+    ActivityWithSubactivity::loop();
+    return;
+  }
+
+  // Handle error state - Confirm retries, Back goes back or home
+  if (state == BrowserState::ERROR) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+      // Check if WiFi is still connected
+      if (WiFi.status() == WL_CONNECTED && WiFi.localIP() != IPAddress(0, 0, 0, 0)) {
+        // WiFi connected - just retry fetching the feed
+        Serial.printf("[%lu] [OPDS] Retry: WiFi connected, retrying fetch\n", millis());
+        state = BrowserState::LOADING;
+        statusMessage = "Loading...";
+        updateRequired = true;
+        fetchFeed(currentPath);
+      } else {
+        // WiFi not connected - launch WiFi selection
+        Serial.printf("[%lu] [OPDS] Retry: WiFi not connected, launching selection\n", millis());
+        launchWifiSelection();
+      }
+    } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      navigateBack();
+    }
+    return;
+  }
+
+  // Handle WiFi check state - only Back works
+  if (state == BrowserState::CHECK_WIFI) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      onGoHome();
+    }
+    return;
+  }
+
+  // Handle loading state - only Back works
+  if (state == BrowserState::LOADING) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      navigateBack();
+    }
+    return;
+  }
+
+  // Handle downloading state - no input allowed
+  if (state == BrowserState::DOWNLOADING) {
+    return;
+  }
+
+  // Handle browsing state
+  if (state == BrowserState::BROWSING) {
+    const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::Up) ||
+                              mappedInput.wasReleased(MappedInputManager::Button::Left);
+    const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::Down) ||
+                              mappedInput.wasReleased(MappedInputManager::Button::Right);
+    const bool skipPage = mappedInput.getHeldTime() > SKIP_PAGE_MS;
+
+    if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+      if (!entries.empty()) {
+        const auto& entry = entries[selectorIndex];
+        if (entry.type == OpdsEntryType::BOOK) {
+          downloadBook(entry);
+        } else {
+          navigateToEntry(entry);
+        }
+      }
+    } else if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      navigateBack();
+    } else if (prevReleased && !entries.empty()) {
+      if (skipPage) {
+        selectorIndex = ((selectorIndex / PAGE_ITEMS - 1) * PAGE_ITEMS + entries.size()) % entries.size();
+      } else {
+        selectorIndex = (selectorIndex + entries.size() - 1) % entries.size();
+      }
+      updateRequired = true;
+    } else if (nextReleased && !entries.empty()) {
+      if (skipPage) {
+        selectorIndex = ((selectorIndex / PAGE_ITEMS + 1) * PAGE_ITEMS) % entries.size();
+      } else {
+        selectorIndex = (selectorIndex + 1) % entries.size();
+      }
+      updateRequired = true;
+    }
+  }
+}
+
+void OpdsBookBrowserActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void OpdsBookBrowserActivity::render() const {
+  renderer.clearScreen();
+
+  const auto pageWidth = renderer.getScreenWidth();
+  const auto pageHeight = renderer.getScreenHeight();
+
+  renderer.drawCenteredText(UI_12_FONT_ID, 15, "Calibre Library", true, EpdFontFamily::BOLD);
+
+  if (state == BrowserState::CHECK_WIFI) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2, statusMessage.c_str());
+    const auto labels = mappedInput.mapLabels("« Back", "", "", "");
+    renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == BrowserState::LOADING) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2, statusMessage.c_str());
+    const auto labels = mappedInput.mapLabels("« Back", "", "", "");
+    renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == BrowserState::ERROR) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2 - 20, "Error:");
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2 + 10, errorMessage.c_str());
+    const auto labels = mappedInput.mapLabels("« Back", "Retry", "", "");
+    renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == BrowserState::DOWNLOADING) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2 - 40, "Downloading...");
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2 - 10, statusMessage.c_str());
+    if (downloadTotal > 0) {
+      const int barWidth = pageWidth - 100;
+      constexpr int barHeight = 20;
+      constexpr int barX = 50;
+      const int barY = pageHeight / 2 + 20;
+      ScreenComponents::drawProgressBar(renderer, barX, barY, barWidth, barHeight, downloadProgress, downloadTotal);
+    }
+    renderer.displayBuffer();
+    return;
+  }
+
+  // Browsing state
+  // Show appropriate button hint based on selected entry type
+  const char* confirmLabel = "Open";
+  if (!entries.empty() && entries[selectorIndex].type == OpdsEntryType::BOOK) {
+    confirmLabel = "Download";
+  }
+  const auto labels = mappedInput.mapLabels("« Back", confirmLabel, "", "");
+  renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
+  if (entries.empty()) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight / 2, "No entries found");
+    renderer.displayBuffer();
+    return;
+  }
+
+  const auto pageStartIndex = selectorIndex / PAGE_ITEMS * PAGE_ITEMS;
+  renderer.fillRect(0, 60 + (selectorIndex % PAGE_ITEMS) * 30 - 2, pageWidth - 1, 30);
+
+  for (size_t i = pageStartIndex; i < entries.size() && i < static_cast<size_t>(pageStartIndex + PAGE_ITEMS); i++) {
+    const auto& entry = entries[i];
+
+    // Format display text with type indicator
+    std::string displayText;
+    if (entry.type == OpdsEntryType::NAVIGATION) {
+      displayText = "> " + entry.title;  // Folder/navigation indicator
+    } else {
+      // Book: "Title - Author" or just "Title"
+      displayText = entry.title;
+      if (!entry.author.empty()) {
+        displayText += " - " + entry.author;
+      }
+    }
+
+    auto item = renderer.truncatedText(UI_10_FONT_ID, displayText.c_str(), renderer.getScreenWidth() - 40);
+    renderer.drawText(UI_10_FONT_ID, 20, 60 + (i % PAGE_ITEMS) * 30, item.c_str(),
+                      i != static_cast<size_t>(selectorIndex));
+  }
+
+  renderer.displayBuffer();
+}
+
+void OpdsBookBrowserActivity::fetchFeed(const std::string& path) {
+  const char* serverUrl = SETTINGS.opdsServerUrl;
+  if (strlen(serverUrl) == 0) {
+    state = BrowserState::ERROR;
+    errorMessage = "No server URL configured";
+    updateRequired = true;
+    return;
+  }
+
+  std::string url = UrlUtils::buildUrl(serverUrl, path);
+  Serial.printf("[%lu] [OPDS] Fetching: %s\n", millis(), url.c_str());
+
+  std::string content;
+  if (!HttpDownloader::fetchUrl(url, content)) {
+    state = BrowserState::ERROR;
+    errorMessage = "Failed to fetch feed";
+    updateRequired = true;
+    return;
+  }
+
+  OpdsParser parser;
+  if (!parser.parse(content.c_str(), content.size())) {
+    state = BrowserState::ERROR;
+    errorMessage = "Failed to parse feed";
+    updateRequired = true;
+    return;
+  }
+
+  entries = parser.getEntries();
+  selectorIndex = 0;
+
+  if (entries.empty()) {
+    state = BrowserState::ERROR;
+    errorMessage = "No entries found";
+    updateRequired = true;
+    return;
+  }
+
+  state = BrowserState::BROWSING;
+  updateRequired = true;
+}
+
+void OpdsBookBrowserActivity::navigateToEntry(const OpdsEntry& entry) {
+  // Push current path to history before navigating
+  navigationHistory.push_back(currentPath);
+  currentPath = entry.href;
+
+  state = BrowserState::LOADING;
+  statusMessage = "Loading...";
+  entries.clear();
+  selectorIndex = 0;
+  updateRequired = true;
+
+  fetchFeed(currentPath);
+}
+
+void OpdsBookBrowserActivity::navigateBack() {
+  if (navigationHistory.empty()) {
+    // At root, go home
+    onGoHome();
+  } else {
+    // Go back to previous catalog
+    currentPath = navigationHistory.back();
+    navigationHistory.pop_back();
+
+    state = BrowserState::LOADING;
+    statusMessage = "Loading...";
+    entries.clear();
+    selectorIndex = 0;
+    updateRequired = true;
+
+    fetchFeed(currentPath);
+  }
+}
+
+void OpdsBookBrowserActivity::downloadBook(const OpdsEntry& book) {
+  state = BrowserState::DOWNLOADING;
+  statusMessage = book.title;
+  downloadProgress = 0;
+  downloadTotal = 0;
+  updateRequired = true;
+
+  // Build full download URL
+  std::string downloadUrl = UrlUtils::buildUrl(SETTINGS.opdsServerUrl, book.href);
+
+  // Create sanitized filename: "Title - Author.epub" or just "Title.epub" if no author
+  std::string baseName = book.title;
+  if (!book.author.empty()) {
+    baseName += " - " + book.author;
+  }
+  std::string filename = "/" + StringUtils::sanitizeFilename(baseName) + ".epub";
+
+  Serial.printf("[%lu] [OPDS] Downloading: %s -> %s\n", millis(), downloadUrl.c_str(), filename.c_str());
+
+  const auto result =
+      HttpDownloader::downloadToFile(downloadUrl, filename, [this](const size_t downloaded, const size_t total) {
+        downloadProgress = downloaded;
+        downloadTotal = total;
+        updateRequired = true;
+      });
+
+  if (result == HttpDownloader::OK) {
+    Serial.printf("[%lu] [OPDS] Download complete: %s\n", millis(), filename.c_str());
+    state = BrowserState::BROWSING;
+    updateRequired = true;
+  } else {
+    state = BrowserState::ERROR;
+    errorMessage = "Download failed";
+    updateRequired = true;
+  }
+}
+
+void OpdsBookBrowserActivity::checkAndConnectWifi() {
+  // Already connected? Verify connection is valid by checking IP
+  if (WiFi.status() == WL_CONNECTED && WiFi.localIP() != IPAddress(0, 0, 0, 0)) {
+    state = BrowserState::LOADING;
+    statusMessage = "Loading...";
+    updateRequired = true;
+    fetchFeed(currentPath);
+    return;
+  }
+
+  // Not connected - launch WiFi selection screen directly
+  launchWifiSelection();
+}
+
+void OpdsBookBrowserActivity::launchWifiSelection() {
+  state = BrowserState::WIFI_SELECTION;
+  updateRequired = true;
+
+  enterNewActivity(new WifiSelectionActivity(renderer, mappedInput,
+                                             [this](const bool connected) { onWifiSelectionComplete(connected); }));
+}
+
+void OpdsBookBrowserActivity::onWifiSelectionComplete(const bool connected) {
+  exitActivity();
+
+  if (connected) {
+    Serial.printf("[%lu] [OPDS] WiFi connected via selection, fetching feed\n", millis());
+    state = BrowserState::LOADING;
+    statusMessage = "Loading...";
+    updateRequired = true;
+    fetchFeed(currentPath);
+  } else {
+    Serial.printf("[%lu] [OPDS] WiFi selection cancelled/failed\n", millis());
+    // Force disconnect to ensure clean state for next retry
+    // This prevents stale connection status from interfering
+    WiFi.disconnect();
+    WiFi.mode(WIFI_OFF);
+    state = BrowserState::ERROR;
+    errorMessage = "WiFi connection failed";
+    updateRequired = true;
+  }
+}

src/activities/browser/OpdsBookBrowserActivity.h

@@ -0,0 +1,65 @@
+#pragma once
+#include <OpdsParser.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <string>
+#include <vector>
+
+#include "../ActivityWithSubactivity.h"
+
+/**
+ * Activity for browsing and downloading books from an OPDS server.
+ * Supports navigation through catalog hierarchy and downloading EPUBs.
+ * When WiFi connection fails, launches WiFi selection to let user connect.
+ */
+class OpdsBookBrowserActivity final : public ActivityWithSubactivity {
+ public:
+  enum class BrowserState {
+    CHECK_WIFI,      // Checking WiFi connection
+    WIFI_SELECTION,  // WiFi selection subactivity is active
+    LOADING,         // Fetching OPDS feed
+    BROWSING,        // Displaying entries (navigation or books)
+    DOWNLOADING,     // Downloading selected EPUB
+    ERROR            // Error state with message
+  };
+
+  explicit OpdsBookBrowserActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                   const std::function<void()>& onGoHome)
+      : ActivityWithSubactivity("OpdsBookBrowser", renderer, mappedInput), onGoHome(onGoHome) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+
+ private:
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  bool updateRequired = false;
+
+  BrowserState state = BrowserState::LOADING;
+  std::vector<OpdsEntry> entries;
+  std::vector<std::string> navigationHistory;  // Stack of previous feed paths for back navigation
+  std::string currentPath;                     // Current feed path being displayed
+  int selectorIndex = 0;
+  std::string errorMessage;
+  std::string statusMessage;
+  size_t downloadProgress = 0;
+  size_t downloadTotal = 0;
+
+  const std::function<void()> onGoHome;
+
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render() const;
+
+  void checkAndConnectWifi();
+  void launchWifiSelection();
+  void onWifiSelectionComplete(bool connected);
+  void fetchFeed(const std::string& path);
+  void navigateToEntry(const OpdsEntry& entry);
+  void navigateBack();
+  void downloadBook(const OpdsEntry& book);
+};

src/activities/home/HomeActivity.cpp

@@ -4,17 +4,28 @@
 #include <GfxRenderer.h>
 #include <SDCardManager.h>
 
+#include <cstring>
+#include <vector>
+
+#include "Battery.h"
+#include "CrossPointSettings.h"
 #include "CrossPointState.h"
 #include "MappedInputManager.h"
 #include "ScreenComponents.h"
 #include "fontIds.h"
+#include "util/StringUtils.h"
 
 void HomeActivity::taskTrampoline(void* param) {
   auto* self = static_cast<HomeActivity*>(param);
   self->displayTaskLoop();
 }
 
-int HomeActivity::getMenuItemCount() const { return hasContinueReading ? 4 : 3; }
+int HomeActivity::getMenuItemCount() const {
+  int count = 3;  // Browse files, File transfer, Settings
+  if (hasContinueReading) count++;
+  if (hasOpdsUrl) count++;
+  return count;
+}
 
 void HomeActivity::onEnter() {
   Activity::onEnter();
@@ -24,6 +35,9 @@ void HomeActivity::onEnter() {
   // Check if we have a book to continue reading
   hasContinueReading = !APP_STATE.openEpubPath.empty() && SdMan.exists(APP_STATE.openEpubPath.c_str());
 
+  // Check if OPDS browser URL is configured
+  hasOpdsUrl = strlen(SETTINGS.opdsServerUrl) > 0;
+
   if (hasContinueReading) {
     // Extract filename from path for display
     lastBookTitle = APP_STATE.openEpubPath;
@@ -32,10 +46,8 @@ void HomeActivity::onEnter() {
       lastBookTitle = lastBookTitle.substr(lastSlash + 1);
     }
 
-    const std::string ext4 = lastBookTitle.length() >= 4 ? lastBookTitle.substr(lastBookTitle.length() - 4) : "";
-    const std::string ext5 = lastBookTitle.length() >= 5 ? lastBookTitle.substr(lastBookTitle.length() - 5) : "";
     // If epub, try to load the metadata for title/author
-    if (ext5 == ".epub") {
+    if (StringUtils::checkFileExtension(lastBookTitle, ".epub")) {
       Epub epub(APP_STATE.openEpubPath, "/.crosspoint");
       epub.load(false);
       if (!epub.getTitle().empty()) {
@@ -44,9 +56,9 @@ void HomeActivity::onEnter() {
       if (!epub.getAuthor().empty()) {
         lastBookAuthor = std::string(epub.getAuthor());
       }
-    } else if (ext5 == ".xtch") {
+    } else if (StringUtils::checkFileExtension(lastBookTitle, ".xtch")) {
       lastBookTitle.resize(lastBookTitle.length() - 5);
-    } else if (ext4 == ".xtc") {
+    } else if (StringUtils::checkFileExtension(lastBookTitle, ".xtc")) {
       lastBookTitle.resize(lastBookTitle.length() - 4);
     }
   }
@@ -57,7 +69,7 @@ void HomeActivity::onEnter() {
   updateRequired = true;
 
   xTaskCreate(&HomeActivity::taskTrampoline, "HomeActivityTask",
-              2048,               // Stack size
+              4096,               // Stack size
               this,               // Parameters
               1,                  // Priority
               &displayTaskHandle  // Task handle
@@ -86,26 +98,24 @@ void HomeActivity::loop() {
   const int menuCount = getMenuItemCount();
 
   if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
-    if (hasContinueReading) {
+    // Calculate dynamic indices based on which options are available
-      // Menu: Continue Reading, Browse, File transfer, Settings
+    int idx = 0;
-      if (selectorIndex == 0) {
+    const int continueIdx = hasContinueReading ? idx++ : -1;
-        onContinueReading();
+    const int browseFilesIdx = idx++;
-      } else if (selectorIndex == 1) {
+    const int opdsLibraryIdx = hasOpdsUrl ? idx++ : -1;
-        onReaderOpen();
+    const int fileTransferIdx = idx++;
-      } else if (selectorIndex == 2) {
+    const int settingsIdx = idx;
-        onFileTransferOpen();
+
-      } else if (selectorIndex == 3) {
+    if (selectorIndex == continueIdx) {
-        onSettingsOpen();
+      onContinueReading();
-      }
+    } else if (selectorIndex == browseFilesIdx) {
-    } else {
+      onReaderOpen();
-      // Menu: Browse, File transfer, Settings
+    } else if (selectorIndex == opdsLibraryIdx) {
-      if (selectorIndex == 0) {
+      onOpdsBrowserOpen();
-        onReaderOpen();
+    } else if (selectorIndex == fileTransferIdx) {
-      } else if (selectorIndex == 1) {
+      onFileTransferOpen();
-        onFileTransferOpen();
+    } else if (selectorIndex == settingsIdx) {
-      } else if (selectorIndex == 2) {
+      onSettingsOpen();
-        onSettingsOpen();
-      }
     }
   } else if (prevPressed) {
     selectorIndex = (selectorIndex + menuCount - 1) % menuCount;
@@ -277,24 +287,31 @@ void HomeActivity::render() const {
     renderer.drawCenteredText(UI_10_FONT_ID, y + renderer.getLineHeight(UI_12_FONT_ID), "Start reading below");
   }
 
-  // --- Bottom menu tiles (indices 1-3) ---
+  // --- Bottom menu tiles ---
-  const int menuTileWidth = pageWidth - 2 * margin;
+  // Build menu items dynamically
-  constexpr int menuTileHeight = 50;
+  std::vector<const char*> menuItems = {"Browse Files", "File Transfer", "Settings"};
-  constexpr int menuSpacing = 10;
+  if (hasOpdsUrl) {
-  constexpr int totalMenuHeight = 3 * menuTileHeight + 2 * menuSpacing;
+    // Insert Calibre Library after Browse Files
+    menuItems.insert(menuItems.begin() + 1, "Calibre Library");
+  }
 
-  int menuStartY = bookY + bookHeight + 20;
+  const int menuTileWidth = pageWidth - 2 * margin;
+  constexpr int menuTileHeight = 45;
+  constexpr int menuSpacing = 8;
+  const int totalMenuHeight =
+      static_cast<int>(menuItems.size()) * menuTileHeight + (static_cast<int>(menuItems.size()) - 1) * menuSpacing;
+
+  int menuStartY = bookY + bookHeight + 15;
   // Ensure we don't collide with the bottom button legend
   const int maxMenuStartY = pageHeight - bottomMargin - totalMenuHeight - margin;
   if (menuStartY > maxMenuStartY) {
     menuStartY = maxMenuStartY;
   }
 
-  for (int i = 0; i < 3; ++i) {
+  for (size_t i = 0; i < menuItems.size(); ++i) {
-    constexpr const char* items[3] = {"Browse files", "File transfer", "Settings"};
+    const int overallIndex = static_cast<int>(i) + (hasContinueReading ? 1 : 0);
-    const int overallIndex = i + (getMenuItemCount() - 3);
     constexpr int tileX = margin;
-    const int tileY = menuStartY + i * (menuTileHeight + menuSpacing);
+    const int tileY = menuStartY + static_cast<int>(i) * (menuTileHeight + menuSpacing);
     const bool selected = selectorIndex == overallIndex;
 
     if (selected) {
@@ -303,7 +320,7 @@ void HomeActivity::render() const {
       renderer.drawRect(tileX, tileY, menuTileWidth, menuTileHeight);
     }
 
-    const char* label = items[i];
+    const char* label = menuItems[i];
     const int textWidth = renderer.getTextWidth(UI_10_FONT_ID, label);
     const int textX = tileX + (menuTileWidth - textWidth) / 2;
     const int lineHeight = renderer.getLineHeight(UI_10_FONT_ID);
@@ -316,7 +333,13 @@ void HomeActivity::render() const {
   const auto labels = mappedInput.mapLabels("", "Confirm", "Up", "Down");
   renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
 
-  ScreenComponents::drawBattery(renderer, 20, pageHeight - 70);
+  const bool showBatteryPercentage =
+      SETTINGS.hideBatteryPercentage != CrossPointSettings::HIDE_BATTERY_PERCENTAGE::HIDE_ALWAYS;
+  // get percentage so we can align text properly
+  const uint16_t percentage = battery.readPercentage();
+  const auto percentageText = showBatteryPercentage ? std::to_string(percentage) + "%" : "";
+  const auto batteryX = pageWidth - 25 - renderer.getTextWidth(SMALL_FONT_ID, percentageText.c_str());
+  ScreenComponents::drawBattery(renderer, batteryX, 10, showBatteryPercentage);
 
   renderer.displayBuffer();
 }

src/activities/home/HomeActivity.h

@@ -13,12 +13,14 @@ class HomeActivity final : public Activity {
   int selectorIndex = 0;
   bool updateRequired = false;
   bool hasContinueReading = false;
+  bool hasOpdsUrl = false;
   std::string lastBookTitle;
   std::string lastBookAuthor;
   const std::function<void()> onContinueReading;
   const std::function<void()> onReaderOpen;
   const std::function<void()> onSettingsOpen;
   const std::function<void()> onFileTransferOpen;
+  const std::function<void()> onOpdsBrowserOpen;
 
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
@@ -28,12 +30,14 @@ class HomeActivity final : public Activity {
  public:
   explicit HomeActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                         const std::function<void()>& onContinueReading, const std::function<void()>& onReaderOpen,
-                        const std::function<void()>& onSettingsOpen, const std::function<void()>& onFileTransferOpen)
+                        const std::function<void()>& onSettingsOpen, const std::function<void()>& onFileTransferOpen,
+                        const std::function<void()>& onOpdsBrowserOpen)
       : Activity("Home", renderer, mappedInput),
         onContinueReading(onContinueReading),
         onReaderOpen(onReaderOpen),
         onSettingsOpen(onSettingsOpen),
-        onFileTransferOpen(onFileTransferOpen) {}
+        onFileTransferOpen(onFileTransferOpen),
+        onOpdsBrowserOpen(onOpdsBrowserOpen) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/network/CalibreWirelessActivity.cpp

@@ -0,0 +1,756 @@
+#include "CalibreWirelessActivity.h"
+
+#include <GfxRenderer.h>
+#include <HardwareSerial.h>
+#include <SDCardManager.h>
+#include <WiFi.h>
+
+#include <cstring>
+
+#include "MappedInputManager.h"
+#include "ScreenComponents.h"
+#include "fontIds.h"
+#include "util/StringUtils.h"
+
+namespace {
+constexpr uint16_t UDP_PORTS[] = {54982, 48123, 39001, 44044, 59678};
+constexpr uint16_t LOCAL_UDP_PORT = 8134;  // Port to receive responses
+}  // namespace
+
+void CalibreWirelessActivity::displayTaskTrampoline(void* param) {
+  auto* self = static_cast<CalibreWirelessActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void CalibreWirelessActivity::networkTaskTrampoline(void* param) {
+  auto* self = static_cast<CalibreWirelessActivity*>(param);
+  self->networkTaskLoop();
+}
+
+void CalibreWirelessActivity::onEnter() {
+  Activity::onEnter();
+
+  renderingMutex = xSemaphoreCreateMutex();
+  stateMutex = xSemaphoreCreateMutex();
+
+  state = WirelessState::DISCOVERING;
+  statusMessage = "Discovering Calibre...";
+  errorMessage.clear();
+  calibreHostname.clear();
+  calibreHost.clear();
+  calibrePort = 0;
+  calibreAltPort = 0;
+  currentFilename.clear();
+  currentFileSize = 0;
+  bytesReceived = 0;
+  inBinaryMode = false;
+  recvBuffer.clear();
+
+  updateRequired = true;
+
+  // Start UDP listener for Calibre responses
+  udp.begin(LOCAL_UDP_PORT);
+
+  // Create display task
+  xTaskCreate(&CalibreWirelessActivity::displayTaskTrampoline, "CalDisplayTask", 2048, this, 1, &displayTaskHandle);
+
+  // Create network task with larger stack for JSON parsing
+  xTaskCreate(&CalibreWirelessActivity::networkTaskTrampoline, "CalNetworkTask", 12288, this, 2, &networkTaskHandle);
+}
+
+void CalibreWirelessActivity::onExit() {
+  Activity::onExit();
+
+  // Turn off WiFi when exiting
+  WiFi.mode(WIFI_OFF);
+
+  // Stop UDP listening
+  udp.stop();
+
+  // Close TCP client if connected
+  if (tcpClient.connected()) {
+    tcpClient.stop();
+  }
+
+  // Close any open file
+  if (currentFile) {
+    currentFile.close();
+  }
+
+  // Acquire stateMutex before deleting network task to avoid race condition
+  xSemaphoreTake(stateMutex, portMAX_DELAY);
+  if (networkTaskHandle) {
+    vTaskDelete(networkTaskHandle);
+    networkTaskHandle = nullptr;
+  }
+  xSemaphoreGive(stateMutex);
+
+  // Acquire renderingMutex before deleting display task
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+
+  vSemaphoreDelete(stateMutex);
+  stateMutex = nullptr;
+}
+
+void CalibreWirelessActivity::loop() {
+  if (mappedInput.wasPressed(MappedInputManager::Button::Back)) {
+    onComplete();
+    return;
+  }
+}
+
+void CalibreWirelessActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(50 / portTICK_PERIOD_MS);
+  }
+}
+
+void CalibreWirelessActivity::networkTaskLoop() {
+  while (true) {
+    xSemaphoreTake(stateMutex, portMAX_DELAY);
+    const auto currentState = state;
+    xSemaphoreGive(stateMutex);
+
+    switch (currentState) {
+      case WirelessState::DISCOVERING:
+        listenForDiscovery();
+        break;
+
+      case WirelessState::CONNECTING:
+      case WirelessState::WAITING:
+      case WirelessState::RECEIVING:
+        handleTcpClient();
+        break;
+
+      case WirelessState::COMPLETE:
+      case WirelessState::DISCONNECTED:
+      case WirelessState::ERROR:
+        // Just wait, user will exit
+        vTaskDelay(100 / portTICK_PERIOD_MS);
+        break;
+    }
+
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void CalibreWirelessActivity::listenForDiscovery() {
+  // Broadcast "hello" on all UDP discovery ports to find Calibre
+  for (const uint16_t port : UDP_PORTS) {
+    udp.beginPacket("255.255.255.255", port);
+    udp.write(reinterpret_cast<const uint8_t*>("hello"), 5);
+    udp.endPacket();
+  }
+
+  // Wait for Calibre's response
+  vTaskDelay(500 / portTICK_PERIOD_MS);
+
+  // Check for response
+  const int packetSize = udp.parsePacket();
+  if (packetSize > 0) {
+    char buffer[256];
+    const int len = udp.read(buffer, sizeof(buffer) - 1);
+    if (len > 0) {
+      buffer[len] = '\0';
+
+      // Parse Calibre's response format:
+      // "calibre wireless device client (on hostname);port,content_server_port"
+      // or just the hostname and port info
+      std::string response(buffer);
+
+      // Try to extract host and port
+      // Format: "calibre wireless device client (on HOSTNAME);PORT,..."
+      size_t onPos = response.find("(on ");
+      size_t closePos = response.find(')');
+      size_t semiPos = response.find(';');
+      size_t commaPos = response.find(',', semiPos);
+
+      if (semiPos != std::string::npos) {
+        // Get ports after semicolon (format: "port1,port2")
+        std::string portStr;
+        if (commaPos != std::string::npos && commaPos > semiPos) {
+          portStr = response.substr(semiPos + 1, commaPos - semiPos - 1);
+          // Get alternative port after comma
+          std::string altPortStr = response.substr(commaPos + 1);
+          // Trim whitespace and non-digits from alt port
+          size_t altEnd = 0;
+          while (altEnd < altPortStr.size() && altPortStr[altEnd] >= '0' && altPortStr[altEnd] <= '9') {
+            altEnd++;
+          }
+          if (altEnd > 0) {
+            calibreAltPort = static_cast<uint16_t>(std::stoi(altPortStr.substr(0, altEnd)));
+          }
+        } else {
+          portStr = response.substr(semiPos + 1);
+        }
+
+        // Trim whitespace from main port
+        while (!portStr.empty() && (portStr[0] == ' ' || portStr[0] == '\t')) {
+          portStr = portStr.substr(1);
+        }
+
+        if (!portStr.empty()) {
+          calibrePort = static_cast<uint16_t>(std::stoi(portStr));
+        }
+
+        // Get hostname if present, otherwise use sender IP
+        if (onPos != std::string::npos && closePos != std::string::npos && closePos > onPos + 4) {
+          calibreHostname = response.substr(onPos + 4, closePos - onPos - 4);
+        }
+      }
+
+      // Use the sender's IP as the host to connect to
+      calibreHost = udp.remoteIP().toString().c_str();
+      if (calibreHostname.empty()) {
+        calibreHostname = calibreHost;
+      }
+
+      if (calibrePort > 0) {
+        // Connect to Calibre's TCP server - try main port first, then alt port
+        setState(WirelessState::CONNECTING);
+        setStatus("Connecting to " + calibreHostname + "...");
+
+        // Small delay before connecting
+        vTaskDelay(100 / portTICK_PERIOD_MS);
+
+        bool connected = false;
+
+        // Try main port first
+        if (tcpClient.connect(calibreHost.c_str(), calibrePort, 5000)) {
+          connected = true;
+        }
+
+        // Try alternative port if main failed
+        if (!connected && calibreAltPort > 0) {
+          vTaskDelay(200 / portTICK_PERIOD_MS);
+          if (tcpClient.connect(calibreHost.c_str(), calibreAltPort, 5000)) {
+            connected = true;
+          }
+        }
+
+        if (connected) {
+          setState(WirelessState::WAITING);
+          setStatus("Connected to " + calibreHostname + "\nWaiting for commands...");
+        } else {
+          // Don't set error yet, keep trying discovery
+          setState(WirelessState::DISCOVERING);
+          setStatus("Discovering Calibre...\n(Connection failed, retrying)");
+          calibrePort = 0;
+          calibreAltPort = 0;
+        }
+      }
+    }
+  }
+}
+
+void CalibreWirelessActivity::handleTcpClient() {
+  if (!tcpClient.connected()) {
+    setState(WirelessState::DISCONNECTED);
+    setStatus("Calibre disconnected");
+    return;
+  }
+
+  if (inBinaryMode) {
+    receiveBinaryData();
+    return;
+  }
+
+  std::string message;
+  if (readJsonMessage(message)) {
+    // Parse opcode from JSON array format: [opcode, {...}]
+    // Find the opcode (first number after '[')
+    size_t start = message.find('[');
+    if (start != std::string::npos) {
+      start++;
+      size_t end = message.find(',', start);
+      if (end != std::string::npos) {
+        const int opcodeInt = std::stoi(message.substr(start, end - start));
+        if (opcodeInt < 0 || opcodeInt >= OpCode::ERROR) {
+          Serial.printf("[%lu] [CAL] Invalid opcode: %d\n", millis(), opcodeInt);
+          sendJsonResponse(OpCode::OK, "{}");
+          return;
+        }
+        const auto opcode = static_cast<OpCode>(opcodeInt);
+
+        // Extract data object (everything after the comma until the last ']')
+        size_t dataStart = end + 1;
+        size_t dataEnd = message.rfind(']');
+        std::string data = "";
+        if (dataEnd != std::string::npos && dataEnd > dataStart) {
+          data = message.substr(dataStart, dataEnd - dataStart);
+        }
+
+        handleCommand(opcode, data);
+      }
+    }
+  }
+}
+
+bool CalibreWirelessActivity::readJsonMessage(std::string& message) {
+  // Read available data into buffer
+  int available = tcpClient.available();
+  if (available > 0) {
+    // Limit buffer growth to prevent memory issues
+    if (recvBuffer.size() > 100000) {
+      recvBuffer.clear();
+      return false;
+    }
+    // Read in chunks
+    char buf[1024];
+    while (available > 0) {
+      int toRead = std::min(available, static_cast<int>(sizeof(buf)));
+      int bytesRead = tcpClient.read(reinterpret_cast<uint8_t*>(buf), toRead);
+      if (bytesRead > 0) {
+        recvBuffer.append(buf, bytesRead);
+        available -= bytesRead;
+      } else {
+        break;
+      }
+    }
+  }
+
+  if (recvBuffer.empty()) {
+    return false;
+  }
+
+  // Find '[' which marks the start of JSON
+  size_t bracketPos = recvBuffer.find('[');
+  if (bracketPos == std::string::npos) {
+    // No '[' found - if buffer is getting large, something is wrong
+    if (recvBuffer.size() > 1000) {
+      recvBuffer.clear();
+    }
+    return false;
+  }
+
+  // Try to extract length from digits before '['
+  // Calibre ALWAYS sends a length prefix, so if it's not valid digits, it's garbage
+  size_t msgLen = 0;
+  bool validPrefix = false;
+
+  if (bracketPos > 0 && bracketPos <= 12) {
+    // Check if prefix is all digits
+    bool allDigits = true;
+    for (size_t i = 0; i < bracketPos; i++) {
+      char c = recvBuffer[i];
+      if (c < '0' || c > '9') {
+        allDigits = false;
+        break;
+      }
+    }
+    if (allDigits) {
+      msgLen = std::stoul(recvBuffer.substr(0, bracketPos));
+      validPrefix = true;
+    }
+  }
+
+  if (!validPrefix) {
+    // Not a valid length prefix - discard everything up to '[' and treat '[' as start
+    if (bracketPos > 0) {
+      recvBuffer = recvBuffer.substr(bracketPos);
+    }
+    // Without length prefix, we can't reliably parse - wait for more data
+    // that hopefully starts with a proper length prefix
+    return false;
+  }
+
+  // Sanity check the message length
+  if (msgLen > 1000000) {
+    recvBuffer = recvBuffer.substr(bracketPos + 1);  // Skip past this '[' and try again
+    return false;
+  }
+
+  // Check if we have the complete message
+  size_t totalNeeded = bracketPos + msgLen;
+  if (recvBuffer.size() < totalNeeded) {
+    // Not enough data yet - wait for more
+    return false;
+  }
+
+  // Extract the message
+  message = recvBuffer.substr(bracketPos, msgLen);
+
+  // Keep the rest in buffer (may contain binary data or next message)
+  if (recvBuffer.size() > totalNeeded) {
+    recvBuffer = recvBuffer.substr(totalNeeded);
+  } else {
+    recvBuffer.clear();
+  }
+
+  return true;
+}
+
+void CalibreWirelessActivity::sendJsonResponse(const OpCode opcode, const std::string& data) {
+  // Format: length + [opcode, {data}]
+  std::string json = "[" + std::to_string(opcode) + "," + data + "]";
+  const std::string lengthPrefix = std::to_string(json.length());
+  json.insert(0, lengthPrefix);
+
+  tcpClient.write(reinterpret_cast<const uint8_t*>(json.c_str()), json.length());
+  tcpClient.flush();
+}
+
+void CalibreWirelessActivity::handleCommand(const OpCode opcode, const std::string& data) {
+  switch (opcode) {
+    case OpCode::GET_INITIALIZATION_INFO:
+      handleGetInitializationInfo(data);
+      break;
+    case OpCode::GET_DEVICE_INFORMATION:
+      handleGetDeviceInformation();
+      break;
+    case OpCode::FREE_SPACE:
+      handleFreeSpace();
+      break;
+    case OpCode::GET_BOOK_COUNT:
+      handleGetBookCount();
+      break;
+    case OpCode::SEND_BOOK:
+      handleSendBook(data);
+      break;
+    case OpCode::SEND_BOOK_METADATA:
+      handleSendBookMetadata(data);
+      break;
+    case OpCode::DISPLAY_MESSAGE:
+      handleDisplayMessage(data);
+      break;
+    case OpCode::NOOP:
+      handleNoop(data);
+      break;
+    case OpCode::SET_CALIBRE_DEVICE_INFO:
+    case OpCode::SET_CALIBRE_DEVICE_NAME:
+      // These set metadata about the connected Calibre instance.
+      // We don't need this info, just acknowledge receipt.
+      sendJsonResponse(OpCode::OK, "{}");
+      break;
+    case OpCode::SET_LIBRARY_INFO:
+      // Library metadata (name, UUID) - not needed for receiving books
+      sendJsonResponse(OpCode::OK, "{}");
+      break;
+    case OpCode::SEND_BOOKLISTS:
+      // Calibre asking us to send our book list. We report 0 books in
+      // handleGetBookCount, so this is effectively a no-op.
+      sendJsonResponse(OpCode::OK, "{}");
+      break;
+    case OpCode::TOTAL_SPACE:
+      handleFreeSpace();
+      break;
+    default:
+      Serial.printf("[%lu] [CAL] Unknown opcode: %d\n", millis(), opcode);
+      sendJsonResponse(OpCode::OK, "{}");
+      break;
+  }
+}
+
+void CalibreWirelessActivity::handleGetInitializationInfo(const std::string& data) {
+  setState(WirelessState::WAITING);
+  setStatus("Connected to " + calibreHostname +
+            "\nWaiting for transfer...\n\nIf transfer fails, enable\n'Ignore free space' in Calibre's\nSmartDevice "
+            "plugin settings.");
+
+  // Build response with device capabilities
+  // Format must match what Calibre expects from a smart device
+  std::string response = "{";
+  response += "\"appName\":\"CrossPoint\",";
+  response += "\"acceptedExtensions\":[\"epub\"],";
+  response += "\"cacheUsesLpaths\":true,";
+  response += "\"canAcceptLibraryInfo\":true,";
+  response += "\"canDeleteMultipleBooks\":true,";
+  response += "\"canReceiveBookBinary\":true,";
+  response += "\"canSendOkToSendbook\":true,";
+  response += "\"canStreamBooks\":true,";
+  response += "\"canStreamMetadata\":true,";
+  response += "\"canUseCachedMetadata\":true,";
+  // ccVersionNumber: Calibre Companion protocol version. 212 matches CC 5.4.20+.
+  // Using a known version ensures compatibility with Calibre's feature detection.
+  response += "\"ccVersionNumber\":212,";
+  // coverHeight: Max cover image height. We don't process covers, so this is informational only.
+  response += "\"coverHeight\":800,";
+  response += "\"deviceKind\":\"CrossPoint\",";
+  response += "\"deviceName\":\"CrossPoint\",";
+  response += "\"extensionPathLengths\":{\"epub\":37},";
+  response += "\"maxBookContentPacketLen\":4096,";
+  response += "\"passwordHash\":\"\",";
+  response += "\"useUuidFileNames\":false,";
+  response += "\"versionOK\":true";
+  response += "}";
+
+  sendJsonResponse(OpCode::OK, response);
+}
+
+void CalibreWirelessActivity::handleGetDeviceInformation() {
+  std::string response = "{";
+  response += "\"device_info\":{";
+  response += "\"device_store_uuid\":\"" + getDeviceUuid() + "\",";
+  response += "\"device_name\":\"CrossPoint Reader\",";
+  response += "\"device_version\":\"" CROSSPOINT_VERSION "\"";
+  response += "},";
+  response += "\"version\":1,";
+  response += "\"device_version\":\"" CROSSPOINT_VERSION "\"";
+  response += "}";
+
+  sendJsonResponse(OpCode::OK, response);
+}
+
+void CalibreWirelessActivity::handleFreeSpace() {
+  // TODO: Report actual SD card free space instead of hardcoded value
+  // Report 10GB free space for now
+  sendJsonResponse(OpCode::OK, "{\"free_space_on_device\":10737418240}");
+}
+
+void CalibreWirelessActivity::handleGetBookCount() {
+  // We report 0 books - Calibre will send books without checking for duplicates
+  std::string response = "{\"count\":0,\"willStream\":true,\"willScan\":false}";
+  sendJsonResponse(OpCode::OK, response);
+}
+
+void CalibreWirelessActivity::handleSendBook(const std::string& data) {
+  // Manually extract lpath and length from SEND_BOOK data
+  // Full JSON parsing crashes on large metadata, so we just extract what we need
+
+  // Extract "lpath" field - format: "lpath": "value"
+  std::string lpath;
+  size_t lpathPos = data.find("\"lpath\"");
+  if (lpathPos != std::string::npos) {
+    size_t colonPos = data.find(':', lpathPos + 7);
+    if (colonPos != std::string::npos) {
+      size_t quoteStart = data.find('"', colonPos + 1);
+      if (quoteStart != std::string::npos) {
+        size_t quoteEnd = data.find('"', quoteStart + 1);
+        if (quoteEnd != std::string::npos) {
+          lpath = data.substr(quoteStart + 1, quoteEnd - quoteStart - 1);
+        }
+      }
+    }
+  }
+
+  // Extract top-level "length" field - must track depth to skip nested objects
+  // The metadata contains nested "length" fields (e.g., cover image length)
+  size_t length = 0;
+  int depth = 0;
+  for (size_t i = 0; i < data.size(); i++) {
+    char c = data[i];
+    if (c == '{' || c == '[') {
+      depth++;
+    } else if (c == '}' || c == ']') {
+      depth--;
+    } else if (depth == 1 && c == '"') {
+      // At top level, check if this is "length"
+      if (i + 9 < data.size() && data.substr(i, 8) == "\"length\"") {
+        // Found top-level "length" - extract the number after ':'
+        size_t colonPos = data.find(':', i + 8);
+        if (colonPos != std::string::npos) {
+          size_t numStart = colonPos + 1;
+          while (numStart < data.size() && (data[numStart] == ' ' || data[numStart] == '\t')) {
+            numStart++;
+          }
+          size_t numEnd = numStart;
+          while (numEnd < data.size() && data[numEnd] >= '0' && data[numEnd] <= '9') {
+            numEnd++;
+          }
+          if (numEnd > numStart) {
+            length = std::stoul(data.substr(numStart, numEnd - numStart));
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  if (lpath.empty() || length == 0) {
+    sendJsonResponse(OpCode::ERROR, "{\"message\":\"Invalid book data\"}");
+    return;
+  }
+
+  // Extract filename from lpath
+  std::string filename = lpath;
+  const size_t lastSlash = filename.rfind('/');
+  if (lastSlash != std::string::npos) {
+    filename = filename.substr(lastSlash + 1);
+  }
+
+  // Sanitize and create full path
+  currentFilename = "/" + StringUtils::sanitizeFilename(filename);
+  if (!StringUtils::checkFileExtension(currentFilename, ".epub")) {
+    currentFilename += ".epub";
+  }
+  currentFileSize = length;
+  bytesReceived = 0;
+
+  setState(WirelessState::RECEIVING);
+  setStatus("Receiving: " + filename);
+
+  // Open file for writing
+  if (!SdMan.openFileForWrite("CAL", currentFilename.c_str(), currentFile)) {
+    setError("Failed to create file");
+    sendJsonResponse(OpCode::ERROR, "{\"message\":\"Failed to create file\"}");
+    return;
+  }
+
+  // Send OK to start receiving binary data
+  sendJsonResponse(OpCode::OK, "{}");
+
+  // Switch to binary mode
+  inBinaryMode = true;
+  binaryBytesRemaining = length;
+
+  // Check if recvBuffer has leftover data (binary file data that arrived with the JSON)
+  if (!recvBuffer.empty()) {
+    size_t toWrite = std::min(recvBuffer.size(), binaryBytesRemaining);
+    size_t written = currentFile.write(reinterpret_cast<const uint8_t*>(recvBuffer.data()), toWrite);
+    bytesReceived += written;
+    binaryBytesRemaining -= written;
+    recvBuffer = recvBuffer.substr(toWrite);
+    updateRequired = true;
+  }
+}
+
+void CalibreWirelessActivity::handleSendBookMetadata(const std::string& data) {
+  // We receive metadata after the book - just acknowledge
+  sendJsonResponse(OpCode::OK, "{}");
+}
+
+void CalibreWirelessActivity::handleDisplayMessage(const std::string& data) {
+  // Calibre may send messages to display
+  // Check messageKind - 1 means password error
+  if (data.find("\"messageKind\":1") != std::string::npos) {
+    setError("Password required");
+  }
+  sendJsonResponse(OpCode::OK, "{}");
+}
+
+void CalibreWirelessActivity::handleNoop(const std::string& data) {
+  // Check for ejecting flag
+  if (data.find("\"ejecting\":true") != std::string::npos) {
+    setState(WirelessState::DISCONNECTED);
+    setStatus("Calibre disconnected");
+  }
+  sendJsonResponse(OpCode::NOOP, "{}");
+}
+
+void CalibreWirelessActivity::receiveBinaryData() {
+  const int available = tcpClient.available();
+  if (available == 0) {
+    // Check if connection is still alive
+    if (!tcpClient.connected()) {
+      currentFile.close();
+      inBinaryMode = false;
+      setError("Transfer interrupted");
+    }
+    return;
+  }
+
+  uint8_t buffer[1024];
+  const size_t toRead = std::min(sizeof(buffer), binaryBytesRemaining);
+  const size_t bytesRead = tcpClient.read(buffer, toRead);
+
+  if (bytesRead > 0) {
+    currentFile.write(buffer, bytesRead);
+    bytesReceived += bytesRead;
+    binaryBytesRemaining -= bytesRead;
+    updateRequired = true;
+
+    if (binaryBytesRemaining == 0) {
+      // Transfer complete
+      currentFile.flush();
+      currentFile.close();
+      inBinaryMode = false;
+
+      setState(WirelessState::WAITING);
+      setStatus("Received: " + currentFilename + "\nWaiting for more...");
+
+      // Send OK to acknowledge completion
+      sendJsonResponse(OpCode::OK, "{}");
+    }
+  }
+}
+
+void CalibreWirelessActivity::render() const {
+  renderer.clearScreen();
+
+  const auto pageWidth = renderer.getScreenWidth();
+  const auto pageHeight = renderer.getScreenHeight();
+
+  // Draw header
+  renderer.drawCenteredText(UI_12_FONT_ID, 30, "Calibre Wireless", true, EpdFontFamily::BOLD);
+
+  // Draw IP address
+  const std::string ipAddr = WiFi.localIP().toString().c_str();
+  renderer.drawCenteredText(UI_10_FONT_ID, 60, ("IP: " + ipAddr).c_str());
+
+  // Draw status message
+  int statusY = pageHeight / 2 - 40;
+
+  // Split status message by newlines and draw each line
+  std::string status = statusMessage;
+  size_t pos = 0;
+  while ((pos = status.find('\n')) != std::string::npos) {
+    renderer.drawCenteredText(UI_10_FONT_ID, statusY, status.substr(0, pos).c_str());
+    statusY += 25;
+    status = status.substr(pos + 1);
+  }
+  if (!status.empty()) {
+    renderer.drawCenteredText(UI_10_FONT_ID, statusY, status.c_str());
+    statusY += 25;
+  }
+
+  // Draw progress if receiving
+  if (state == WirelessState::RECEIVING && currentFileSize > 0) {
+    const int barWidth = pageWidth - 100;
+    constexpr int barHeight = 20;
+    constexpr int barX = 50;
+    const int barY = statusY + 20;
+    ScreenComponents::drawProgressBar(renderer, barX, barY, barWidth, barHeight, bytesReceived, currentFileSize);
+  }
+
+  // Draw error if present
+  if (!errorMessage.empty()) {
+    renderer.drawCenteredText(UI_10_FONT_ID, pageHeight - 120, errorMessage.c_str());
+  }
+
+  // Draw button hints
+  const auto labels = mappedInput.mapLabels("Back", "", "", "");
+  renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
+  renderer.displayBuffer();
+}
+
+std::string CalibreWirelessActivity::getDeviceUuid() const {
+  // Generate a consistent UUID based on MAC address
+  uint8_t mac[6];
+  WiFi.macAddress(mac);
+
+  char uuid[37];
+  snprintf(uuid, sizeof(uuid), "%02x%02x%02x%02x-%02x%02x-4000-8000-%02x%02x%02x%02x%02x%02x", mac[0], mac[1], mac[2],
+           mac[3], mac[4], mac[5], mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+
+  return std::string(uuid);
+}
+
+void CalibreWirelessActivity::setState(WirelessState newState) {
+  xSemaphoreTake(stateMutex, portMAX_DELAY);
+  state = newState;
+  xSemaphoreGive(stateMutex);
+  updateRequired = true;
+}
+
+void CalibreWirelessActivity::setStatus(const std::string& message) {
+  statusMessage = message;
+  updateRequired = true;
+}
+
+void CalibreWirelessActivity::setError(const std::string& message) {
+  errorMessage = message;
+  setState(WirelessState::ERROR);
+}

src/activities/network/CalibreWirelessActivity.h

@@ -0,0 +1,135 @@
+#pragma once
+#include <SDCardManager.h>
+#include <WiFiClient.h>
+#include <WiFiUdp.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <string>
+
+#include "activities/Activity.h"
+
+/**
+ * CalibreWirelessActivity implements Calibre's "wireless device" protocol.
+ * This allows Calibre desktop to send books directly to the device over WiFi.
+ *
+ * Protocol specification sourced from Calibre's smart device driver:
+ * https://github.com/kovidgoyal/calibre/blob/master/src/calibre/devices/smart_device_app/driver.py
+ *
+ * Protocol overview:
+ * 1. Device broadcasts "hello" on UDP ports 54982, 48123, 39001, 44044, 59678
+ * 2. Calibre responds with its TCP server address
+ * 3. Device connects to Calibre's TCP server
+ * 4. Calibre sends JSON commands with length-prefixed messages
+ * 5. Books are transferred as binary data after SEND_BOOK command
+ */
+class CalibreWirelessActivity final : public Activity {
+  // Calibre wireless device states
+  enum class WirelessState {
+    DISCOVERING,   // Listening for Calibre server broadcasts
+    CONNECTING,    // Establishing TCP connection
+    WAITING,       // Connected, waiting for commands
+    RECEIVING,     // Receiving a book file
+    COMPLETE,      // Transfer complete
+    DISCONNECTED,  // Calibre disconnected
+    ERROR          // Connection/transfer error
+  };
+
+  // Calibre protocol opcodes (from calibre/devices/smart_device_app/driver.py)
+  enum OpCode : uint8_t {
+    OK = 0,
+    SET_CALIBRE_DEVICE_INFO = 1,
+    SET_CALIBRE_DEVICE_NAME = 2,
+    GET_DEVICE_INFORMATION = 3,
+    TOTAL_SPACE = 4,
+    FREE_SPACE = 5,
+    GET_BOOK_COUNT = 6,
+    SEND_BOOKLISTS = 7,
+    SEND_BOOK = 8,
+    GET_INITIALIZATION_INFO = 9,
+    BOOK_DONE = 11,
+    NOOP = 12,  // Was incorrectly 18
+    DELETE_BOOK = 13,
+    GET_BOOK_FILE_SEGMENT = 14,
+    GET_BOOK_METADATA = 15,
+    SEND_BOOK_METADATA = 16,
+    DISPLAY_MESSAGE = 17,
+    CALIBRE_BUSY = 18,
+    SET_LIBRARY_INFO = 19,
+    ERROR = 20,
+  };
+
+  TaskHandle_t displayTaskHandle = nullptr;
+  TaskHandle_t networkTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  SemaphoreHandle_t stateMutex = nullptr;
+  bool updateRequired = false;
+
+  WirelessState state = WirelessState::DISCOVERING;
+  const std::function<void()> onComplete;
+
+  // UDP discovery
+  WiFiUDP udp;
+
+  // TCP connection (we connect to Calibre)
+  WiFiClient tcpClient;
+  std::string calibreHost;
+  uint16_t calibrePort = 0;
+  uint16_t calibreAltPort = 0;  // Alternative port (content server)
+  std::string calibreHostname;
+
+  // Transfer state
+  std::string currentFilename;
+  size_t currentFileSize = 0;
+  size_t bytesReceived = 0;
+  std::string statusMessage;
+  std::string errorMessage;
+
+  // Protocol state
+  bool inBinaryMode = false;
+  size_t binaryBytesRemaining = 0;
+  FsFile currentFile;
+  std::string recvBuffer;  // Buffer for incoming data (like KOReader)
+
+  static void displayTaskTrampoline(void* param);
+  static void networkTaskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  [[noreturn]] void networkTaskLoop();
+  void render() const;
+
+  // Network operations
+  void listenForDiscovery();
+  void handleTcpClient();
+  bool readJsonMessage(std::string& message);
+  void sendJsonResponse(OpCode opcode, const std::string& data);
+  void handleCommand(OpCode opcode, const std::string& data);
+  void receiveBinaryData();
+
+  // Protocol handlers
+  void handleGetInitializationInfo(const std::string& data);
+  void handleGetDeviceInformation();
+  void handleFreeSpace();
+  void handleGetBookCount();
+  void handleSendBook(const std::string& data);
+  void handleSendBookMetadata(const std::string& data);
+  void handleDisplayMessage(const std::string& data);
+  void handleNoop(const std::string& data);
+
+  // Utility
+  std::string getDeviceUuid() const;
+  void setState(WirelessState newState);
+  void setStatus(const std::string& message);
+  void setError(const std::string& message);
+
+ public:
+  explicit CalibreWirelessActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                   const std::function<void()>& onComplete)
+      : Activity("CalibreWireless", renderer, mappedInput), onComplete(onComplete) {}
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+  bool preventAutoSleep() override { return true; }
+  bool skipLoopDelay() override { return true; }
+};

src/activities/reader/EpubReaderActivity.cpp

@@ -164,6 +164,8 @@ void EpubReaderActivity::loop() {
   const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
                             mappedInput.wasReleased(MappedInputManager::Button::Left);
   const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                            (SETTINGS.shortPwrBtn == CrossPointSettings::SHORT_PWRBTN::PAGE_TURN &&
+                             mappedInput.wasReleased(MappedInputManager::Button::Power)) ||
                             mappedInput.wasReleased(MappedInputManager::Button::Right);
 
   if (!prevReleased && !nextReleased) {
@@ -400,7 +402,7 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
 
   // grayscale rendering
   // TODO: Only do this if font supports it
-  {
+  if (SETTINGS.textAntiAliasing) {
     renderer.clearScreen(0x00);
     renderer.setRenderMode(GfxRenderer::GRAYSCALE_LSB);
     page->render(renderer, SETTINGS.getReaderFontId(), orientedMarginLeft, orientedMarginTop);
@@ -429,6 +431,8 @@ void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const in
                            SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
   const bool showChapterTitle = SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::NO_PROGRESS ||
                                 SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::FULL;
+  const bool showBatteryPercentage =
+      SETTINGS.hideBatteryPercentage == CrossPointSettings::HIDE_BATTERY_PERCENTAGE::HIDE_NEVER;
 
   // Position status bar near the bottom of the logical screen, regardless of orientation
   const auto screenHeight = renderer.getScreenHeight();
@@ -451,7 +455,7 @@ void EpubReaderActivity::renderStatusBar(const int orientedMarginRight, const in
   }
 
   if (showBattery) {
-    ScreenComponents::drawBattery(renderer, orientedMarginLeft, textY);
+    ScreenComponents::drawBattery(renderer, orientedMarginLeft + 1, textY, showBatteryPercentage);
   }
 
   if (showChapterTitle) {

src/activities/reader/EpubReaderChapterSelectionActivity.cpp

@@ -38,7 +38,9 @@ int EpubReaderChapterSelectionActivity::getPageItems() const {
   constexpr int lineHeight = 30;
 
   const int screenHeight = renderer.getScreenHeight();
-  const int availableHeight = screenHeight - startY;
+  const int endY = screenHeight - lineHeight;
+
+  const int availableHeight = endY - startY;
   int items = availableHeight / lineHeight;
 
   // Ensure we always have at least one item per page to avoid division by zero
@@ -201,5 +203,8 @@ void EpubReaderChapterSelectionActivity::renderScreen() {
     }
   }
 
+  const auto labels = mappedInput.mapLabels("« Back", "Select", "Up", "Down");
+  renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
   renderer.displayBuffer();
 }

src/activities/reader/FileSelectionActivity.cpp

@@ -5,6 +5,7 @@
 
 #include "MappedInputManager.h"
 #include "fontIds.h"
+#include "util/StringUtils.h"
 
 namespace {
 constexpr int PAGE_ITEMS = 23;
@@ -29,7 +30,6 @@ void FileSelectionActivity::taskTrampoline(void* param) {
 
 void FileSelectionActivity::loadFiles() {
   files.clear();
-  selectorIndex = 0;
 
   auto root = SdMan.open(basepath.c_str());
   if (!root || !root.isDirectory()) {
@@ -39,7 +39,7 @@ void FileSelectionActivity::loadFiles() {
 
   root.rewindDirectory();
 
-  char name[128];
+  char name[500];
   for (auto file = root.openNextFile(); file; file = root.openNextFile()) {
     file.getName(name, sizeof(name));
     if (name[0] == '.' || strcmp(name, "System Volume Information") == 0) {
@@ -51,9 +51,8 @@ void FileSelectionActivity::loadFiles() {
       files.emplace_back(std::string(name) + "/");
     } else {
       auto filename = std::string(name);
-      std::string ext4 = filename.length() >= 4 ? filename.substr(filename.length() - 4) : "";
+      if (StringUtils::checkFileExtension(filename, ".epub") || StringUtils::checkFileExtension(filename, ".xtch") ||
-      std::string ext5 = filename.length() >= 5 ? filename.substr(filename.length() - 5) : "";
+          StringUtils::checkFileExtension(filename, ".xtc")) {
-      if (ext5 == ".epub" || ext5 == ".xtch" || ext4 == ".xtc") {
         files.emplace_back(filename);
       }
     }
@@ -124,6 +123,7 @@ void FileSelectionActivity::loop() {
     if (files[selectorIndex].back() == '/') {
       basepath += files[selectorIndex].substr(0, files[selectorIndex].length() - 1);
       loadFiles();
+      selectorIndex = 0;
       updateRequired = true;
     } else {
       onSelect(basepath + files[selectorIndex]);
@@ -132,9 +132,16 @@ void FileSelectionActivity::loop() {
     // Short press: go up one directory, or go home if at root
     if (mappedInput.getHeldTime() < GO_HOME_MS) {
       if (basepath != "/") {
+        const std::string oldPath = basepath;
+
         basepath.replace(basepath.find_last_of('/'), std::string::npos, "");
         if (basepath.empty()) basepath = "/";
         loadFiles();
+
+        const auto pos = oldPath.find_last_of('/');
+        const std::string dirName = oldPath.substr(pos + 1) + "/";
+        selectorIndex = findEntry(dirName);
+
         updateRequired = true;
       } else {
         onGoHome();
@@ -187,10 +194,16 @@ void FileSelectionActivity::render() const {
 
   const auto pageStartIndex = selectorIndex / PAGE_ITEMS * PAGE_ITEMS;
   renderer.fillRect(0, 60 + (selectorIndex % PAGE_ITEMS) * 30 - 2, pageWidth - 1, 30);
-  for (int i = pageStartIndex; i < files.size() && i < pageStartIndex + PAGE_ITEMS; i++) {
+  for (size_t i = pageStartIndex; i < files.size() && i < pageStartIndex + PAGE_ITEMS; i++) {
     auto item = renderer.truncatedText(UI_10_FONT_ID, files[i].c_str(), renderer.getScreenWidth() - 40);
     renderer.drawText(UI_10_FONT_ID, 20, 60 + (i % PAGE_ITEMS) * 30, item.c_str(), i != selectorIndex);
   }
 
   renderer.displayBuffer();
 }
+
+size_t FileSelectionActivity::findEntry(const std::string& name) const {
+  for (size_t i = 0; i < files.size(); i++)
+    if (files[i] == name) return i;
+  return 0;
+}

src/activities/reader/FileSelectionActivity.h

@@ -14,7 +14,7 @@ class FileSelectionActivity final : public Activity {
   SemaphoreHandle_t renderingMutex = nullptr;
   std::string basepath = "/";
   std::vector<std::string> files;
-  int selectorIndex = 0;
+  size_t selectorIndex = 0;
   bool updateRequired = false;
   const std::function<void(const std::string&)> onSelect;
   const std::function<void()> onGoHome;
@@ -24,6 +24,8 @@ class FileSelectionActivity final : public Activity {
   void render() const;
   void loadFiles();
 
+  size_t findEntry(const std::string& name) const;
+
  public:
   explicit FileSelectionActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                                  const std::function<void(const std::string&)>& onSelect,

src/activities/reader/ReaderActivity.cpp

@@ -6,6 +6,7 @@
 #include "Xtc.h"
 #include "XtcReaderActivity.h"
 #include "activities/util/FullScreenMessageActivity.h"
+#include "util/StringUtils.h"
 
 std::string ReaderActivity::extractFolderPath(const std::string& filePath) {
   const auto lastSlash = filePath.find_last_of('/');
@@ -16,14 +17,7 @@ std::string ReaderActivity::extractFolderPath(const std::string& filePath) {
 }
 
 bool ReaderActivity::isXtcFile(const std::string& path) {
-  if (path.length() < 4) return false;
+  return StringUtils::checkFileExtension(path, ".xtc") || StringUtils::checkFileExtension(path, ".xtch");
-  std::string ext4 = path.substr(path.length() - 4);
-  if (ext4 == ".xtc") return true;
-  if (path.length() >= 5) {
-    std::string ext5 = path.substr(path.length() - 5);
-    if (ext5 == ".xtch") return true;
-  }
-  return false;
 }
 
 std::unique_ptr<Epub> ReaderActivity::loadEpub(const std::string& path) {

src/activities/reader/XtcReaderActivity.cpp

@@ -112,6 +112,8 @@ void XtcReaderActivity::loop() {
   const bool prevReleased = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
                             mappedInput.wasReleased(MappedInputManager::Button::Left);
   const bool nextReleased = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                            (SETTINGS.shortPwrBtn == CrossPointSettings::SHORT_PWRBTN::PAGE_TURN &&
+                             mappedInput.wasReleased(MappedInputManager::Button::Power)) ||
                             mappedInput.wasReleased(MappedInputManager::Button::Right);
 
   if (!prevReleased && !nextReleased) {

src/activities/reader/XtcReaderChapterSelectionActivity.cpp

@@ -14,7 +14,9 @@ int XtcReaderChapterSelectionActivity::getPageItems() const {
   constexpr int lineHeight = 30;
 
   const int screenHeight = renderer.getScreenHeight();
-  const int availableHeight = screenHeight - startY;
+  const int endY = screenHeight - lineHeight;
+
+  const int availableHeight = endY - startY;
   int items = availableHeight / lineHeight;
   if (items < 1) {
     items = 1;
@@ -147,5 +149,8 @@ void XtcReaderChapterSelectionActivity::renderScreen() {
     renderer.drawText(UI_10_FONT_ID, 20, 60 + (i % pageItems) * 30, title, i != selectorIndex);
   }
 
+  const auto labels = mappedInput.mapLabels("« Back", "Select", "Up", "Down");
+  renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
   renderer.displayBuffer();
 }

src/activities/settings/CalibreSettingsActivity.cpp

@@ -0,0 +1,169 @@
+#include "CalibreSettingsActivity.h"
+
+#include <GfxRenderer.h>
+#include <WiFi.h>
+
+#include <cstring>
+
+#include "CrossPointSettings.h"
+#include "MappedInputManager.h"
+#include "activities/network/CalibreWirelessActivity.h"
+#include "activities/network/WifiSelectionActivity.h"
+#include "activities/util/KeyboardEntryActivity.h"
+#include "fontIds.h"
+
+namespace {
+constexpr int MENU_ITEMS = 2;
+const char* menuNames[MENU_ITEMS] = {"Calibre Web URL", "Connect as Wireless Device"};
+}  // namespace
+
+void CalibreSettingsActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<CalibreSettingsActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void CalibreSettingsActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+
+  renderingMutex = xSemaphoreCreateMutex();
+  selectedIndex = 0;
+  updateRequired = true;
+
+  xTaskCreate(&CalibreSettingsActivity::taskTrampoline, "CalibreSettingsTask",
+              4096,               // Stack size
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+}
+
+void CalibreSettingsActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+void CalibreSettingsActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
+  if (mappedInput.wasPressed(MappedInputManager::Button::Back)) {
+    onBack();
+    return;
+  }
+
+  if (mappedInput.wasPressed(MappedInputManager::Button::Confirm)) {
+    handleSelection();
+    return;
+  }
+
+  if (mappedInput.wasPressed(MappedInputManager::Button::Up) ||
+      mappedInput.wasPressed(MappedInputManager::Button::Left)) {
+    selectedIndex = (selectedIndex + MENU_ITEMS - 1) % MENU_ITEMS;
+    updateRequired = true;
+  } else if (mappedInput.wasPressed(MappedInputManager::Button::Down) ||
+             mappedInput.wasPressed(MappedInputManager::Button::Right)) {
+    selectedIndex = (selectedIndex + 1) % MENU_ITEMS;
+    updateRequired = true;
+  }
+}
+
+void CalibreSettingsActivity::handleSelection() {
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+
+  if (selectedIndex == 0) {
+    // Calibre Web URL
+    exitActivity();
+    enterNewActivity(new KeyboardEntryActivity(
+        renderer, mappedInput, "Calibre Web URL", SETTINGS.opdsServerUrl, 10,
+        127,    // maxLength
+        false,  // not password
+        [this](const std::string& url) {
+          strncpy(SETTINGS.opdsServerUrl, url.c_str(), sizeof(SETTINGS.opdsServerUrl) - 1);
+          SETTINGS.opdsServerUrl[sizeof(SETTINGS.opdsServerUrl) - 1] = '\0';
+          SETTINGS.saveToFile();
+          exitActivity();
+          updateRequired = true;
+        },
+        [this]() {
+          exitActivity();
+          updateRequired = true;
+        }));
+  } else if (selectedIndex == 1) {
+    // Wireless Device - launch the activity (handles WiFi connection internally)
+    exitActivity();
+    if (WiFi.status() != WL_CONNECTED) {
+      enterNewActivity(new WifiSelectionActivity(renderer, mappedInput, [this](bool connected) {
+        exitActivity();
+        if (connected) {
+          enterNewActivity(new CalibreWirelessActivity(renderer, mappedInput, [this] {
+            exitActivity();
+            updateRequired = true;
+          }));
+        } else {
+          updateRequired = true;
+        }
+      }));
+    } else {
+      enterNewActivity(new CalibreWirelessActivity(renderer, mappedInput, [this] {
+        exitActivity();
+        updateRequired = true;
+      }));
+    }
+  }
+
+  xSemaphoreGive(renderingMutex);
+}
+
+void CalibreSettingsActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired && !subActivity) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void CalibreSettingsActivity::render() {
+  renderer.clearScreen();
+
+  const auto pageWidth = renderer.getScreenWidth();
+
+  // Draw header
+  renderer.drawCenteredText(UI_12_FONT_ID, 15, "Calibre", true, EpdFontFamily::BOLD);
+
+  // Draw selection highlight
+  renderer.fillRect(0, 60 + selectedIndex * 30 - 2, pageWidth - 1, 30);
+
+  // Draw menu items
+  for (int i = 0; i < MENU_ITEMS; i++) {
+    const int settingY = 60 + i * 30;
+    const bool isSelected = (i == selectedIndex);
+
+    renderer.drawText(UI_10_FONT_ID, 20, settingY, menuNames[i], !isSelected);
+
+    // Draw status for URL setting
+    if (i == 0) {
+      const char* status = (strlen(SETTINGS.opdsServerUrl) > 0) ? "[Set]" : "[Not Set]";
+      const auto width = renderer.getTextWidth(UI_10_FONT_ID, status);
+      renderer.drawText(UI_10_FONT_ID, pageWidth - 20 - width, settingY, status, !isSelected);
+    }
+  }
+
+  // Draw button hints
+  const auto labels = mappedInput.mapLabels("« Back", "Select", "", "");
+  renderer.drawButtonHints(UI_10_FONT_ID, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
+  renderer.displayBuffer();
+}

src/activities/settings/CalibreSettingsActivity.h

@@ -0,0 +1,36 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+
+#include "activities/ActivityWithSubactivity.h"
+
+/**
+ * Submenu for Calibre settings.
+ * Shows Calibre Web URL and Calibre Wireless Device options.
+ */
+class CalibreSettingsActivity final : public ActivityWithSubactivity {
+ public:
+  explicit CalibreSettingsActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                   const std::function<void()>& onBack)
+      : ActivityWithSubactivity("CalibreSettings", renderer, mappedInput), onBack(onBack) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+
+ private:
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  bool updateRequired = false;
+
+  int selectedIndex = 0;
+  const std::function<void()> onBack;
+
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render();
+  void handleSelection();
+};

src/activities/settings/SettingsActivity.cpp

@@ -5,6 +5,7 @@
 
 #include <cstring>
 
+#include "CalibreSettingsActivity.h"
 #include "CrossPointSettings.h"
 #include "KOReaderSettingsActivity.h"
 #include "MappedInputManager.h"
@@ -13,14 +14,16 @@
 
 // Define the static settings list
 namespace {
-constexpr int settingsCount = 17;
+constexpr int settingsCount = 20;
 const SettingInfo settingsList[settingsCount] = {
     // Should match with SLEEP_SCREEN_MODE
     SettingInfo::Enum("Sleep Screen", &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover", "None"}),
     SettingInfo::Enum("Sleep Screen Cover Mode", &CrossPointSettings::sleepScreenCoverMode, {"Fit", "Crop"}),
     SettingInfo::Enum("Status Bar", &CrossPointSettings::statusBar, {"None", "No Progress", "Full"}),
+    SettingInfo::Enum("Hide Battery %", &CrossPointSettings::hideBatteryPercentage, {"Never", "In Reader", "Always"}),
     SettingInfo::Toggle("Extra Paragraph Spacing", &CrossPointSettings::extraParagraphSpacing),
-    SettingInfo::Toggle("Short Power Button Click", &CrossPointSettings::shortPwrBtn),
+    SettingInfo::Toggle("Text Anti-Aliasing", &CrossPointSettings::textAntiAliasing),
+    SettingInfo::Enum("Short Power Button Click", &CrossPointSettings::shortPwrBtn, {"Ignore", "Sleep", "Page Turn"}),
     SettingInfo::Enum("Reading Orientation", &CrossPointSettings::orientation,
                       {"Portrait", "Landscape CW", "Inverted", "Landscape CCW"}),
     SettingInfo::Enum("Front Button Layout", &CrossPointSettings::frontButtonLayout,
@@ -39,6 +42,7 @@ const SettingInfo settingsList[settingsCount] = {
     SettingInfo::Enum("Refresh Frequency", &CrossPointSettings::refreshFrequency,
                       {"1 page", "5 pages", "10 pages", "15 pages", "30 pages"}),
     SettingInfo::Action("KOReader Sync"),
+    SettingInfo::Action("Calibre Settings"),
     SettingInfo::Action("Check for updates")};
 }  // namespace
 
@@ -135,18 +139,26 @@ void SettingsActivity::toggleCurrentSetting() {
       SETTINGS.*(setting.valuePtr) = currentValue + setting.valueRange.step;
     }
   } else if (setting.type == SettingType::ACTION) {
-    if (strcmp(setting.name, "Check for updates") == 0) {
+    if (strcmp(setting.name, "KOReader Sync") == 0) {
       xSemaphoreTake(renderingMutex, portMAX_DELAY);
       exitActivity();
-      enterNewActivity(new OtaUpdateActivity(renderer, mappedInput, [this] {
+      enterNewActivity(new KOReaderSettingsActivity(renderer, mappedInput, [this] {
         exitActivity();
         updateRequired = true;
       }));
       xSemaphoreGive(renderingMutex);
-    } else if (strcmp(setting.name, "KOReader Sync") == 0) {
+    } else if (strcmp(setting.name, "Calibre Settings") == 0) {
       xSemaphoreTake(renderingMutex, portMAX_DELAY);
       exitActivity();
-      enterNewActivity(new KOReaderSettingsActivity(renderer, mappedInput, [this] {
+      enterNewActivity(new CalibreSettingsActivity(renderer, mappedInput, [this] {
+        exitActivity();
+        updateRequired = true;
+      }));
+      xSemaphoreGive(renderingMutex);
+    } else if (strcmp(setting.name, "Check for updates") == 0) {
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      exitActivity();
+      enterNewActivity(new OtaUpdateActivity(renderer, mappedInput, [this] {
         exitActivity();
         updateRequired = true;
       }));

src/main.cpp

@@ -7,6 +7,8 @@
 #include <SPI.h>
 #include <builtinFonts/all.h>
 
+#include <cstring>
+
 #include "Battery.h"
 #include "CrossPointSettings.h"
 #include "CrossPointState.h"
@@ -14,6 +16,7 @@
 #include "MappedInputManager.h"
 #include "activities/boot_sleep/BootActivity.h"
 #include "activities/boot_sleep/SleepActivity.h"
+#include "activities/browser/OpdsBookBrowserActivity.h"
 #include "activities/home/HomeActivity.h"
 #include "activities/network/CrossPointWebServerActivity.h"
 #include "activities/reader/ReaderActivity.h"
@@ -223,10 +226,15 @@ void onGoToSettings() {
   enterNewActivity(new SettingsActivity(renderer, mappedInputManager, onGoHome));
 }
 
+void onGoToBrowser() {
+  exitActivity();
+  enterNewActivity(new OpdsBookBrowserActivity(renderer, mappedInputManager, onGoHome));
+}
+
 void onGoHome() {
   exitActivity();
   enterNewActivity(new HomeActivity(renderer, mappedInputManager, onContinueReading, onGoToReaderHome, onGoToSettings,
-                                    onGoToFileTransfer));
+                                    onGoToFileTransfer, onGoToBrowser));
 }
 
 void setupDisplayAndFonts() {

src/network/CrossPointWebServer.cpp

@@ -194,7 +194,7 @@ void CrossPointWebServer::scanFiles(const char* path, const std::function<void(F
   Serial.printf("[%lu] [WEB] Scanning files in: %s\n", millis(), path);
 
   FsFile file = root.openNextFile();
-  char name[128];
+  char name[500];
   while (file) {
     file.getName(name, sizeof(name));
     auto fileName = String(name);

src/network/HttpDownloader.cpp

@@ -0,0 +1,128 @@
+#include "HttpDownloader.h"
+
+#include <HTTPClient.h>
+#include <HardwareSerial.h>
+#include <WiFiClientSecure.h>
+
+#include <memory>
+
+bool HttpDownloader::fetchUrl(const std::string& url, std::string& outContent) {
+  const std::unique_ptr<WiFiClientSecure> client(new WiFiClientSecure());
+  client->setInsecure();
+  HTTPClient http;
+
+  Serial.printf("[%lu] [HTTP] Fetching: %s\n", millis(), url.c_str());
+
+  http.begin(*client, url.c_str());
+  http.setFollowRedirects(HTTPC_STRICT_FOLLOW_REDIRECTS);
+  http.addHeader("User-Agent", "CrossPoint-ESP32-" CROSSPOINT_VERSION);
+
+  const int httpCode = http.GET();
+  if (httpCode != HTTP_CODE_OK) {
+    Serial.printf("[%lu] [HTTP] Fetch failed: %d\n", millis(), httpCode);
+    http.end();
+    return false;
+  }
+
+  outContent = http.getString().c_str();
+  http.end();
+
+  Serial.printf("[%lu] [HTTP] Fetched %zu bytes\n", millis(), outContent.size());
+  return true;
+}
+
+HttpDownloader::DownloadError HttpDownloader::downloadToFile(const std::string& url, const std::string& destPath,
+                                                             ProgressCallback progress) {
+  const std::unique_ptr<WiFiClientSecure> client(new WiFiClientSecure());
+  client->setInsecure();
+  HTTPClient http;
+
+  Serial.printf("[%lu] [HTTP] Downloading: %s\n", millis(), url.c_str());
+  Serial.printf("[%lu] [HTTP] Destination: %s\n", millis(), destPath.c_str());
+
+  http.begin(*client, url.c_str());
+  http.setFollowRedirects(HTTPC_STRICT_FOLLOW_REDIRECTS);
+  http.addHeader("User-Agent", "CrossPoint-ESP32-" CROSSPOINT_VERSION);
+
+  const int httpCode = http.GET();
+  if (httpCode != HTTP_CODE_OK) {
+    Serial.printf("[%lu] [HTTP] Download failed: %d\n", millis(), httpCode);
+    http.end();
+    return HTTP_ERROR;
+  }
+
+  const size_t contentLength = http.getSize();
+  Serial.printf("[%lu] [HTTP] Content-Length: %zu\n", millis(), contentLength);
+
+  // Remove existing file if present
+  if (SdMan.exists(destPath.c_str())) {
+    SdMan.remove(destPath.c_str());
+  }
+
+  // Open file for writing
+  FsFile file;
+  if (!SdMan.openFileForWrite("HTTP", destPath.c_str(), file)) {
+    Serial.printf("[%lu] [HTTP] Failed to open file for writing\n", millis());
+    http.end();
+    return FILE_ERROR;
+  }
+
+  // Get the stream for chunked reading
+  WiFiClient* stream = http.getStreamPtr();
+  if (!stream) {
+    Serial.printf("[%lu] [HTTP] Failed to get stream\n", millis());
+    file.close();
+    SdMan.remove(destPath.c_str());
+    http.end();
+    return HTTP_ERROR;
+  }
+
+  // Download in chunks
+  uint8_t buffer[DOWNLOAD_CHUNK_SIZE];
+  size_t downloaded = 0;
+  const size_t total = contentLength > 0 ? contentLength : 0;
+
+  while (http.connected() && (contentLength == 0 || downloaded < contentLength)) {
+    const size_t available = stream->available();
+    if (available == 0) {
+      delay(1);
+      continue;
+    }
+
+    const size_t toRead = available < DOWNLOAD_CHUNK_SIZE ? available : DOWNLOAD_CHUNK_SIZE;
+    const size_t bytesRead = stream->readBytes(buffer, toRead);
+
+    if (bytesRead == 0) {
+      break;
+    }
+
+    const size_t written = file.write(buffer, bytesRead);
+    if (written != bytesRead) {
+      Serial.printf("[%lu] [HTTP] Write failed: wrote %zu of %zu bytes\n", millis(), written, bytesRead);
+      file.close();
+      SdMan.remove(destPath.c_str());
+      http.end();
+      return FILE_ERROR;
+    }
+
+    downloaded += bytesRead;
+
+    if (progress && total > 0) {
+      progress(downloaded, total);
+    }
+  }
+
+  file.close();
+  http.end();
+
+  Serial.printf("[%lu] [HTTP] Downloaded %zu bytes\n", millis(), downloaded);
+
+  // Verify download size if known
+  if (contentLength > 0 && downloaded != contentLength) {
+    Serial.printf("[%lu] [HTTP] Size mismatch: got %zu, expected %zu\n", millis(), downloaded, contentLength);
+    SdMan.remove(destPath.c_str());
+    return HTTP_ERROR;
+  }
+
+  return OK;
+}

src/network/HttpDownloader.h

@@ -0,0 +1,42 @@
+#pragma once
+#include <SDCardManager.h>
+
+#include <functional>
+#include <string>
+
+/**
+ * HTTP client utility for fetching content and downloading files.
+ * Wraps WiFiClientSecure and HTTPClient for HTTPS requests.
+ */
+class HttpDownloader {
+ public:
+  using ProgressCallback = std::function<void(size_t downloaded, size_t total)>;
+
+  enum DownloadError {
+    OK = 0,
+    HTTP_ERROR,
+    FILE_ERROR,
+    ABORTED,
+  };
+
+  /**
+   * Fetch text content from a URL.
+   * @param url The URL to fetch
+   * @param outContent The fetched content (output)
+   * @return true if fetch succeeded, false on error
+   */
+  static bool fetchUrl(const std::string& url, std::string& outContent);
+
+  /**
+   * Download a file to the SD card.
+   * @param url The URL to download
+   * @param destPath The destination path on SD card
+   * @param progress Optional progress callback
+   * @return DownloadError indicating success or failure type
+   */
+  static DownloadError downloadToFile(const std::string& url, const std::string& destPath,
+                                      ProgressCallback progress = nullptr);
+
+ private:
+  static constexpr size_t DOWNLOAD_CHUNK_SIZE = 1024;
+};

src/util/StringUtils.cpp

@@ -0,0 +1,52 @@
+#include "StringUtils.h"
+
+#include <cstring>
+
+namespace StringUtils {
+
+std::string sanitizeFilename(const std::string& name, size_t maxLength) {
+  std::string result;
+  result.reserve(name.size());
+
+  for (char c : name) {
+    // Replace invalid filename characters with underscore
+    if (c == '/' || c == '\\' || c == ':' || c == '*' || c == '?' || c == '"' || c == '<' || c == '>' || c == '|') {
+      result += '_';
+    } else if (c >= 32 && c < 127) {
+      // Keep printable ASCII characters
+      result += c;
+    }
+    // Skip non-printable characters
+  }
+
+  // Trim leading/trailing spaces and dots
+  size_t start = result.find_first_not_of(" .");
+  if (start == std::string::npos) {
+    return "book";  // Fallback if name is all invalid characters
+  }
+  size_t end = result.find_last_not_of(" .");
+  result = result.substr(start, end - start + 1);
+
+  // Limit filename length
+  if (result.length() > maxLength) {
+    result.resize(maxLength);
+  }
+
+  return result.empty() ? "book" : result;
+}
+
+bool checkFileExtension(const std::string& fileName, const char* extension) {
+  if (fileName.length() < strlen(extension)) {
+    return false;
+  }
+
+  const std::string fileExt = fileName.substr(fileName.length() - strlen(extension));
+  for (size_t i = 0; i < fileExt.length(); i++) {
+    if (tolower(fileExt[i]) != tolower(extension[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace StringUtils

src/util/StringUtils.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <string>
+
+namespace StringUtils {
+
+/**
+ * Sanitize a string for use as a filename.
+ * Replaces invalid characters with underscores, trims spaces/dots,
+ * and limits length to maxLength characters.
+ */
+std::string sanitizeFilename(const std::string& name, size_t maxLength = 100);
+
+/**
+ * Check if the given filename ends with the specified extension (case-insensitive).
+ */
+bool checkFileExtension(const std::string& fileName, const char* extension);
+
+}  // namespace StringUtils

src/util/UrlUtils.cpp

@@ -0,0 +1,41 @@
+#include "UrlUtils.h"
+
+namespace UrlUtils {
+
+std::string ensureProtocol(const std::string& url) {
+  if (url.find("://") == std::string::npos) {
+    return "http://" + url;
+  }
+  return url;
+}
+
+std::string extractHost(const std::string& url) {
+  const size_t protocolEnd = url.find("://");
+  if (protocolEnd == std::string::npos) {
+    // No protocol, find first slash
+    const size_t firstSlash = url.find('/');
+    return firstSlash == std::string::npos ? url : url.substr(0, firstSlash);
+  }
+  // Find the first slash after the protocol
+  const size_t hostStart = protocolEnd + 3;
+  const size_t pathStart = url.find('/', hostStart);
+  return pathStart == std::string::npos ? url : url.substr(0, pathStart);
+}
+
+std::string buildUrl(const std::string& serverUrl, const std::string& path) {
+  const std::string urlWithProtocol = ensureProtocol(serverUrl);
+  if (path.empty()) {
+    return urlWithProtocol;
+  }
+  if (path[0] == '/') {
+    // Absolute path - use just the host
+    return extractHost(urlWithProtocol) + path;
+  }
+  // Relative path - append to server URL
+  if (urlWithProtocol.back() == '/') {
+    return urlWithProtocol + path;
+  }
+  return urlWithProtocol + "/" + path;
+}
+
+}  // namespace UrlUtils

src/util/UrlUtils.h

@@ -0,0 +1,23 @@
+#pragma once
+#include <string>
+
+namespace UrlUtils {
+
+/**
+ * Prepend http:// if no protocol specified (server will redirect to https if needed)
+ */
+std::string ensureProtocol(const std::string& url);
+
+/**
+ * Extract host with protocol from URL (e.g., "http://example.com" from "http://example.com/path")
+ */
+std::string extractHost(const std::string& url);
+
+/**
+ * Build full URL from server URL and path.
+ * If path starts with /, it's an absolute path from the host root.
+ * Otherwise, it's relative to the server URL.
+ */
+std::string buildUrl(const std::string& serverUrl, const std::string& path);
+
+}  // namespace UrlUtils