Cut release 0.9.0

## Summary

* Use single unified cache file for book spine, table of contents, and
core metadata (title, author, cover image)
* Use new temp item store file in OPF parsing to store items to be
rescaned when parsing spine
  * This avoids us holding these items in memory
* Use new toc.bin.tmp and spine.bin.tmp to build out partial toc / spine
data as part of parsing content.opf and the NCX file
  * These files are re-read multiple times to ultimately build book.bin

## Additional Context

* Spec for file format included below as an image
* This should help with:
  * #10 
  * #60 
  * #99

lib/Epub/Epub.cpp

@@ -1,13 +1,11 @@
 #include "Epub.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
 #include <JpegToBmpConverter.h>
 #include <SD.h>
 #include <ZipFile.h>
 
-#include <map>
-
-#include "Epub/FsHelpers.h"
 #include "Epub/parsers/ContainerParser.h"
 #include "Epub/parsers/ContentOpfParser.h"
 #include "Epub/parsers/TocNcxParser.h"
@@ -44,7 +42,15 @@ bool Epub::findContentOpfFile(std::string* contentOpfFile) const {
   return true;
 }
 
-bool Epub::parseContentOpf(const std::string& contentOpfFilePath) {
+bool Epub::parseContentOpf(BookMetadataCache::BookMetadata& bookMetadata) {
+  std::string contentOpfFilePath;
+  if (!findContentOpfFile(&contentOpfFilePath)) {
+    Serial.printf("[%lu] [EBP] Could not find content.opf in zip\n", millis());
+    return false;
+  }
+
+  contentBasePath = contentOpfFilePath.substr(0, contentOpfFilePath.find_last_of('/') + 1);
+
   Serial.printf("[%lu] [EBP] Parsing content.opf: %s\n", millis(), contentOpfFilePath.c_str());
 
   size_t contentOpfSize;
@@ -53,7 +59,9 @@ bool Epub::parseContentOpf(const std::string& contentOpfFilePath) {
     return false;
   }
 
-  ContentOpfParser opfParser(getBasePath(), contentOpfSize);
+  ContentOpfParser opfParser(getCachePath(), getBasePath(), contentOpfSize, bookMetadataCache.get());
+  Serial.printf("[%lu] [MEM] Free: %d bytes, Total: %d bytes, Min Free: %d bytes\n", millis(), ESP.getFreeHeap(),
+                ESP.getHeapSize(), ESP.getMinFreeHeap());
 
   if (!opfParser.setup()) {
     Serial.printf("[%lu] [EBP] Could not setup content.opf parser\n", millis());
@@ -66,26 +74,20 @@ bool Epub::parseContentOpf(const std::string& contentOpfFilePath) {
   }
 
   // Grab data from opfParser into epub
-  title = opfParser.title;
-  if (!opfParser.coverItemId.empty() && opfParser.items.count(opfParser.coverItemId) > 0) {
-    coverImageItem = opfParser.items.at(opfParser.coverItemId);
-  }
+  bookMetadata.title = opfParser.title;
+  // TODO: Parse author
+  bookMetadata.author = "";
+  bookMetadata.coverItemHref = opfParser.coverItemHref;
 
   if (!opfParser.tocNcxPath.empty()) {
     tocNcxItem = opfParser.tocNcxPath;
   }
 
-  for (auto& spineRef : opfParser.spineRefs) {
-    if (opfParser.items.count(spineRef)) {
-      spine.emplace_back(spineRef, opfParser.items.at(spineRef));
-    }
-  }
-
   Serial.printf("[%lu] [EBP] Successfully parsed content.opf\n", millis());
   return true;
 }
 
-bool Epub::parseTocNcxFile() {
+bool Epub::parseTocNcxFile() const {
   // the ncx file should have been specified in the content.opf file
   if (tocNcxItem.empty()) {
     Serial.printf("[%lu] [EBP] No ncx file specified\n", millis());
@@ -95,13 +97,18 @@ bool Epub::parseTocNcxFile() {
   Serial.printf("[%lu] [EBP] Parsing toc ncx file: %s\n", millis(), tocNcxItem.c_str());
 
   const auto tmpNcxPath = getCachePath() + "/toc.ncx";
-  File tempNcxFile = SD.open(tmpNcxPath.c_str(), FILE_WRITE);
+  File tempNcxFile;
+  if (!FsHelpers::openFileForWrite("EBP", tmpNcxPath, tempNcxFile)) {
+    return false;
+  }
   readItemContentsToStream(tocNcxItem, tempNcxFile, 1024);
   tempNcxFile.close();
-  tempNcxFile = SD.open(tmpNcxPath.c_str(), FILE_READ);
+  if (!FsHelpers::openFileForRead("EBP", tmpNcxPath, tempNcxFile)) {
+    return false;
+  }
   const auto ncxSize = tempNcxFile.size();
 
-  TocNcxParser ncxParser(contentBasePath, ncxSize);
+  TocNcxParser ncxParser(contentBasePath, ncxSize, bookMetadataCache.get());
 
   if (!ncxParser.setup()) {
     Serial.printf("[%lu] [EBP] Could not setup toc ncx parser\n", millis());
@@ -130,9 +137,7 @@ bool Epub::parseTocNcxFile() {
   tempNcxFile.close();
   SD.remove(tmpNcxPath.c_str());
 
-  this->toc = std::move(ncxParser.toc);
-
-  Serial.printf("[%lu] [EBP] Parsed %d TOC items\n", millis(), this->toc.size());
+  Serial.printf("[%lu] [EBP] Parsed TOC items\n", millis());
   return true;
 }
 
@@ -140,48 +145,79 @@ bool Epub::parseTocNcxFile() {
 bool Epub::load() {
   Serial.printf("[%lu] [EBP] Loading ePub: %s\n", millis(), filepath.c_str());
 
-  std::string contentOpfFilePath;
-  if (!findContentOpfFile(&contentOpfFilePath)) {
-    Serial.printf("[%lu] [EBP] Could not find content.opf in zip\n", millis());
+  // Initialize spine/TOC cache
+  bookMetadataCache.reset(new BookMetadataCache(cachePath));
+
+  // Try to load existing cache first
+  if (bookMetadataCache->load()) {
+    Serial.printf("[%lu] [EBP] Loaded ePub: %s\n", millis(), filepath.c_str());
+    return true;
+  }
+
+  // Cache doesn't exist or is invalid, build it
+  Serial.printf("[%lu] [EBP] Cache not found, building spine/TOC cache\n", millis());
+  setupCacheDir();
+
+  // Begin building cache - stream entries to disk immediately
+  if (!bookMetadataCache->beginWrite()) {
+    Serial.printf("[%lu] [EBP] Could not begin writing cache\n", millis());
     return false;
   }
 
-  Serial.printf("[%lu] [EBP] Found content.opf at: %s\n", millis(), contentOpfFilePath.c_str());
-
-  contentBasePath = contentOpfFilePath.substr(0, contentOpfFilePath.find_last_of('/') + 1);
-
-  if (!parseContentOpf(contentOpfFilePath)) {
+  // OPF Pass
+  BookMetadataCache::BookMetadata bookMetadata;
+  if (!bookMetadataCache->beginContentOpfPass()) {
+    Serial.printf("[%lu] [EBP] Could not begin writing content.opf pass\n", millis());
+    return false;
+  }
+  if (!parseContentOpf(bookMetadata)) {
     Serial.printf("[%lu] [EBP] Could not parse content.opf\n", millis());
     return false;
   }
+  if (!bookMetadataCache->endContentOpfPass()) {
+    Serial.printf("[%lu] [EBP] Could not end writing content.opf pass\n", millis());
+    return false;
+  }
 
+  // TOC Pass
+  if (!bookMetadataCache->beginTocPass()) {
+    Serial.printf("[%lu] [EBP] Could not begin writing toc pass\n", millis());
+    return false;
+  }
   if (!parseTocNcxFile()) {
     Serial.printf("[%lu] [EBP] Could not parse toc\n", millis());
     return false;
   }
-
-  initializeSpineItemSizes();
-  Serial.printf("[%lu] [EBP] Loaded ePub: %s\n", millis(), filepath.c_str());
-
-  return true;
-}
-
-void Epub::initializeSpineItemSizes() {
-  Serial.printf("[%lu] [EBP] Calculating book size\n", millis());
-
-  const size_t spineItemsCount = getSpineItemsCount();
-  size_t cumSpineItemSize = 0;
-  const ZipFile zip("/sd" + filepath);
-
-  for (size_t i = 0; i < spineItemsCount; i++) {
-    std::string spineItem = getSpineItem(i);
-    size_t s = 0;
-    getItemSize(zip, spineItem, &s);
-    cumSpineItemSize += s;
-    cumulativeSpineItemSize.emplace_back(cumSpineItemSize);
+  if (!bookMetadataCache->endTocPass()) {
+    Serial.printf("[%lu] [EBP] Could not end writing toc pass\n", millis());
+    return false;
   }
 
-  Serial.printf("[%lu] [EBP] Book size: %lu\n", millis(), cumSpineItemSize);
+  // Close the cache files
+  if (!bookMetadataCache->endWrite()) {
+    Serial.printf("[%lu] [EBP] Could not end writing cache\n", millis());
+    return false;
+  }
+
+  // Build final book.bin
+  if (!bookMetadataCache->buildBookBin(filepath, bookMetadata)) {
+    Serial.printf("[%lu] [EBP] Could not update mappings and sizes\n", millis());
+    return false;
+  }
+
+  if (!bookMetadataCache->cleanupTmpFiles()) {
+    Serial.printf("[%lu] [EBP] Could not cleanup tmp files - ignoring\n", millis());
+  }
+
+  // Reload the cache from disk so it's in the correct state
+  bookMetadataCache.reset(new BookMetadataCache(cachePath));
+  if (!bookMetadataCache->load()) {
+    Serial.printf("[%lu] [EBP] Failed to reload cache after writing\n", millis());
+    return false;
+  }
+
+  Serial.printf("[%lu] [EBP] Loaded ePub: %s\n", millis(), filepath.c_str());
+  return true;
 }
 
 bool Epub::clearCache() const {
@@ -217,7 +253,14 @@ const std::string& Epub::getCachePath() const { return cachePath; }
 
 const std::string& Epub::getPath() const { return filepath; }
 
-const std::string& Epub::getTitle() const { return title; }
+const std::string& Epub::getTitle() const {
+  static std::string blank;
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    return blank;
+  }
+
+  return bookMetadataCache->coreMetadata.title;
+}
 
 std::string Epub::getCoverBmpPath() const { return cachePath + "/cover.bmp"; }
 
@@ -227,24 +270,42 @@ bool Epub::generateCoverBmp() const {
     return true;
   }
 
-  if (coverImageItem.empty()) {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    Serial.printf("[%lu] [EBP] Cannot generate cover BMP, cache not loaded\n", millis());
+    return false;
+  }
+
+  const auto coverImageHref = bookMetadataCache->coreMetadata.coverItemHref;
+  if (coverImageHref.empty()) {
     Serial.printf("[%lu] [EBP] No known cover image\n", millis());
     return false;
   }
 
-  if (coverImageItem.substr(coverImageItem.length() - 4) == ".jpg" ||
-      coverImageItem.substr(coverImageItem.length() - 5) == ".jpeg") {
+  if (coverImageHref.substr(coverImageHref.length() - 4) == ".jpg" ||
+      coverImageHref.substr(coverImageHref.length() - 5) == ".jpeg") {
     Serial.printf("[%lu] [EBP] Generating BMP from JPG cover image\n", millis());
-    File coverJpg = SD.open((getCachePath() + "/.cover.jpg").c_str(), FILE_WRITE, true);
-    readItemContentsToStream(coverImageItem, coverJpg, 1024);
+    const auto coverJpgTempPath = getCachePath() + "/.cover.jpg";
+
+    File coverJpg;
+    if (!FsHelpers::openFileForWrite("EBP", coverJpgTempPath, coverJpg)) {
+      return false;
+    }
+    readItemContentsToStream(coverImageHref, coverJpg, 1024);
     coverJpg.close();
 
-    coverJpg = SD.open((getCachePath() + "/.cover.jpg").c_str(), FILE_READ);
-    File coverBmp = SD.open(getCoverBmpPath().c_str(), FILE_WRITE, true);
+    if (!FsHelpers::openFileForRead("EBP", coverJpgTempPath, coverJpg)) {
+      return false;
+    }
+
+    File coverBmp;
+    if (!FsHelpers::openFileForWrite("EBP", getCoverBmpPath(), coverBmp)) {
+      coverJpg.close();
+      return false;
+    }
     const bool success = JpegToBmpConverter::jpegFileToBmpStream(coverJpg, coverBmp);
     coverJpg.close();
     coverBmp.close();
-    SD.remove((getCachePath() + "/.cover.jpg").c_str());
+    SD.remove(coverJpgTempPath.c_str());
 
     if (!success) {
       Serial.printf("[%lu] [EBP] Failed to generate BMP from JPG cover image\n", millis());
@@ -259,45 +320,9 @@ bool Epub::generateCoverBmp() const {
   return false;
 }
 
-std::string normalisePath(const std::string& path) {
-  std::vector<std::string> components;
-  std::string component;
-
-  for (const auto c : path) {
-    if (c == '/') {
-      if (!component.empty()) {
-        if (component == "..") {
-          if (!components.empty()) {
-            components.pop_back();
-          }
-        } else {
-          components.push_back(component);
-        }
-        component.clear();
-      }
-    } else {
-      component += c;
-    }
-  }
-
-  if (!component.empty()) {
-    components.push_back(component);
-  }
-
-  std::string result;
-  for (const auto& c : components) {
-    if (!result.empty()) {
-      result += "/";
-    }
-    result += c;
-  }
-
-  return result;
-}
-
-uint8_t* Epub::readItemContentsToBytes(const std::string& itemHref, size_t* size, bool trailingNullByte) const {
+uint8_t* Epub::readItemContentsToBytes(const std::string& itemHref, size_t* size, const bool trailingNullByte) const {
   const ZipFile zip("/sd" + filepath);
-  const std::string path = normalisePath(itemHref);
+  const std::string path = FsHelpers::normalisePath(itemHref);
 
   const auto content = zip.readFileToMemory(path.c_str(), size, trailingNullByte);
   if (!content) {
@@ -310,7 +335,7 @@ uint8_t* Epub::readItemContentsToBytes(const std::string& itemHref, size_t* size
 
 bool Epub::readItemContentsToStream(const std::string& itemHref, Print& out, const size_t chunkSize) const {
   const ZipFile zip("/sd" + filepath);
-  const std::string path = normalisePath(itemHref);
+  const std::string path = FsHelpers::normalisePath(itemHref);
 
   return zip.readFileToStream(path.c_str(), out, chunkSize);
 }
@@ -321,103 +346,93 @@ bool Epub::getItemSize(const std::string& itemHref, size_t* size) const {
 }
 
 bool Epub::getItemSize(const ZipFile& zip, const std::string& itemHref, size_t* size) {
-  const std::string path = normalisePath(itemHref);
+  const std::string path = FsHelpers::normalisePath(itemHref);
   return zip.getInflatedFileSize(path.c_str(), size);
 }
 
-int Epub::getSpineItemsCount() const { return spine.size(); }
-
-size_t Epub::getCumulativeSpineItemSize(const int spineIndex) const {
-  if (spineIndex < 0 || spineIndex >= static_cast<int>(cumulativeSpineItemSize.size())) {
-    Serial.printf("[%lu] [EBP] getCumulativeSpineItemSize index:%d is out of range\n", millis(), spineIndex);
+int Epub::getSpineItemsCount() const {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
     return 0;
   }
-  return cumulativeSpineItemSize.at(spineIndex);
+  return bookMetadataCache->getSpineCount();
 }
 
-std::string& Epub::getSpineItem(const int spineIndex) {
-  static std::string emptyString;
-  if (spine.empty()) {
-    Serial.printf("[%lu] [EBP] getSpineItem called but spine is empty\n", millis());
-    return emptyString;
+size_t Epub::getCumulativeSpineItemSize(const int spineIndex) const { return getSpineItem(spineIndex).cumulativeSize; }
+
+BookMetadataCache::SpineEntry Epub::getSpineItem(const int spineIndex) const {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    Serial.printf("[%lu] [EBP] getSpineItem called but cache not loaded\n", millis());
+    return {};
   }
-  if (spineIndex < 0 || spineIndex >= static_cast<int>(spine.size())) {
+
+  if (spineIndex < 0 || spineIndex >= bookMetadataCache->getSpineCount()) {
     Serial.printf("[%lu] [EBP] getSpineItem index:%d is out of range\n", millis(), spineIndex);
-    return spine.at(0).second;
+    return bookMetadataCache->getSpineEntry(0);
   }
 
-  return spine.at(spineIndex).second;
+  return bookMetadataCache->getSpineEntry(spineIndex);
 }
 
-EpubTocEntry& Epub::getTocItem(const int tocTndex) {
-  static EpubTocEntry emptyEntry = {};
-  if (toc.empty()) {
-    Serial.printf("[%lu] [EBP] getTocItem called but toc is empty\n", millis());
-    return emptyEntry;
-  }
-  if (tocTndex < 0 || tocTndex >= static_cast<int>(toc.size())) {
-    Serial.printf("[%lu] [EBP] getTocItem index:%d is out of range\n", millis(), tocTndex);
-    return toc.at(0);
+BookMetadataCache::TocEntry Epub::getTocItem(const int tocIndex) const {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    Serial.printf("[%lu] [EBP] getTocItem called but cache not loaded\n", millis());
+    return {};
   }
 
-  return toc.at(tocTndex);
+  if (tocIndex < 0 || tocIndex >= bookMetadataCache->getTocCount()) {
+    Serial.printf("[%lu] [EBP] getTocItem index:%d is out of range\n", millis(), tocIndex);
+    return {};
+  }
+
+  return bookMetadataCache->getTocEntry(tocIndex);
 }
 
-int Epub::getTocItemsCount() const { return toc.size(); }
+int Epub::getTocItemsCount() const {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    return 0;
+  }
+
+  return bookMetadataCache->getTocCount();
+}
 
 // work out the section index for a toc index
 int Epub::getSpineIndexForTocIndex(const int tocIndex) const {
-  if (tocIndex < 0 || tocIndex >= toc.size()) {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded()) {
+    Serial.printf("[%lu] [EBP] getSpineIndexForTocIndex called but cache not loaded\n", millis());
+    return 0;
+  }
+
+  if (tocIndex < 0 || tocIndex >= bookMetadataCache->getTocCount()) {
     Serial.printf("[%lu] [EBP] getSpineIndexForTocIndex: tocIndex %d out of range\n", millis(), tocIndex);
     return 0;
   }
 
-  // the toc entry should have an href that matches the spine item
-  // so we can find the spine index by looking for the href
-  for (int i = 0; i < spine.size(); i++) {
-    if (spine[i].second == toc[tocIndex].href) {
-      return i;
-    }
-  }
-
-  Serial.printf("[%lu] [EBP] Section not found\n", millis());
-  // not found - default to the start of the book
+  const int spineIndex = bookMetadataCache->getTocEntry(tocIndex).spineIndex;
+  if (spineIndex < 0) {
+    Serial.printf("[%lu] [EBP] Section not found for TOC index %d\n", millis(), tocIndex);
     return 0;
+  }
+
+  return spineIndex;
 }
 
-int Epub::getTocIndexForSpineIndex(const int spineIndex) const {
-  if (spineIndex < 0 || spineIndex >= spine.size()) {
-    Serial.printf("[%lu] [EBP] getTocIndexForSpineIndex: spineIndex %d out of range\n", millis(), spineIndex);
-    return -1;
-  }
-
-  // the toc entry should have an href that matches the spine item
-  // so we can find the toc index by looking for the href
-  for (int i = 0; i < toc.size(); i++) {
-    if (toc[i].href == spine[spineIndex].second) {
-      return i;
-    }
-  }
-
-  Serial.printf("[%lu] [EBP] TOC item not found\n", millis());
-  return -1;
-}
+int Epub::getTocIndexForSpineIndex(const int spineIndex) const { return getSpineItem(spineIndex).tocIndex; }
 
 size_t Epub::getBookSize() const {
-  if (spine.empty()) {
+  if (!bookMetadataCache || !bookMetadataCache->isLoaded() || bookMetadataCache->getSpineCount() == 0) {
     return 0;
   }
   return getCumulativeSpineItemSize(getSpineItemsCount() - 1);
 }
 
 // Calculate progress in book
-uint8_t Epub::calculateProgress(const int currentSpineIndex, const float currentSpineRead) {
-  size_t bookSize = getBookSize();
+uint8_t Epub::calculateProgress(const int currentSpineIndex, const float currentSpineRead) const {
+  const size_t bookSize = getBookSize();
   if (bookSize == 0) {
     return 0;
   }
-  size_t prevChapterSize = (currentSpineIndex >= 1) ? getCumulativeSpineItemSize(currentSpineIndex - 1) : 0;
-  size_t curChapterSize = getCumulativeSpineItemSize(currentSpineIndex) - prevChapterSize;
-  size_t sectionProgSize = currentSpineRead * curChapterSize;
+  const size_t prevChapterSize = (currentSpineIndex >= 1) ? getCumulativeSpineItemSize(currentSpineIndex - 1) : 0;
+  const size_t curChapterSize = getCumulativeSpineItemSize(currentSpineIndex) - prevChapterSize;
+  const size_t sectionProgSize = currentSpineRead * curChapterSize;
   return round(static_cast<float>(prevChapterSize + sectionProgSize) / bookSize * 100.0);
 }

lib/Epub/Epub.h

@@ -1,38 +1,29 @@
 #pragma once
-#include <Print.h>
 
+#include <memory>
 #include <string>
 #include <unordered_map>
 #include <vector>
 
-#include "Epub/EpubTocEntry.h"
+#include "Epub/BookMetadataCache.h"
 
 class ZipFile;
 
 class Epub {
-  // the title read from the EPUB meta data
-  std::string title;
-  // the cover image
-  std::string coverImageItem;
   // the ncx file
   std::string tocNcxItem;
   // where is the EPUBfile?
   std::string filepath;
-  // the spine of the EPUB file
-  std::vector<std::pair<std::string, std::string>> spine;
-  // the file size of the spine items (proxy to book progress)
-  std::vector<size_t> cumulativeSpineItemSize;
-  // the toc of the EPUB file
-  std::vector<EpubTocEntry> toc;
   // the base path for items in the EPUB file
   std::string contentBasePath;
   // Uniq cache key based on filepath
   std::string cachePath;
+  // Spine and TOC cache
+  std::unique_ptr<BookMetadataCache> bookMetadataCache;
 
   bool findContentOpfFile(std::string* contentOpfFile) const;
-  bool parseContentOpf(const std::string& contentOpfFilePath);
-  bool parseTocNcxFile();
-  void initializeSpineItemSizes();
+  bool parseContentOpf(BookMetadataCache::BookMetadata& bookMetadata);
+  bool parseTocNcxFile() const;
   static bool getItemSize(const ZipFile& zip, const std::string& itemHref, size_t* size);
 
  public:
@@ -54,14 +45,14 @@ class Epub {
                                    bool trailingNullByte = false) const;
   bool readItemContentsToStream(const std::string& itemHref, Print& out, size_t chunkSize) const;
   bool getItemSize(const std::string& itemHref, size_t* size) const;
-  std::string& getSpineItem(int spineIndex);
+  BookMetadataCache::SpineEntry getSpineItem(int spineIndex) const;
+  BookMetadataCache::TocEntry getTocItem(int tocIndex) const;
   int getSpineItemsCount() const;
-  size_t getCumulativeSpineItemSize(const int spineIndex) const;
-  EpubTocEntry& getTocItem(int tocIndex);
   int getTocItemsCount() const;
   int getSpineIndexForTocIndex(int tocIndex) const;
   int getTocIndexForSpineIndex(int spineIndex) const;
+  size_t getCumulativeSpineItemSize(int spineIndex) const;
 
   size_t getBookSize() const;
-  uint8_t calculateProgress(const int currentSpineIndex, const float currentSpineRead);
+  uint8_t calculateProgress(const int currentSpineIndex, const float currentSpineRead) const;
 };

lib/Epub/Epub/BookMetadataCache.cpp

@@ -0,0 +1,326 @@
+#include "BookMetadataCache.h"
+
+#include <HardwareSerial.h>
+#include <SD.h>
+#include <Serialization.h>
+#include <ZipFile.h>
+
+#include <vector>
+
+#include "FsHelpers.h"
+
+namespace {
+constexpr uint8_t BOOK_CACHE_VERSION = 1;
+constexpr char bookBinFile[] = "/book.bin";
+constexpr char tmpSpineBinFile[] = "/spine.bin.tmp";
+constexpr char tmpTocBinFile[] = "/toc.bin.tmp";
+}  // namespace
+
+/* ============= WRITING / BUILDING FUNCTIONS ================ */
+
+bool BookMetadataCache::beginWrite() {
+  buildMode = true;
+  spineCount = 0;
+  tocCount = 0;
+  Serial.printf("[%lu] [BMC] Entering write mode\n", millis());
+  return true;
+}
+
+bool BookMetadataCache::beginContentOpfPass() {
+  Serial.printf("[%lu] [BMC] Beginning content opf pass\n", millis());
+
+  // Open spine file for writing
+  return FsHelpers::openFileForWrite("BMC", cachePath + tmpSpineBinFile, spineFile);
+}
+
+bool BookMetadataCache::endContentOpfPass() {
+  spineFile.close();
+  return true;
+}
+
+bool BookMetadataCache::beginTocPass() {
+  Serial.printf("[%lu] [BMC] Beginning toc pass\n", millis());
+
+  // Open spine file for reading
+  if (!FsHelpers::openFileForRead("BMC", cachePath + tmpSpineBinFile, spineFile)) {
+    return false;
+  }
+  if (!FsHelpers::openFileForWrite("BMC", cachePath + tmpTocBinFile, tocFile)) {
+    spineFile.close();
+    return false;
+  }
+  return true;
+}
+
+bool BookMetadataCache::endTocPass() {
+  tocFile.close();
+  spineFile.close();
+  return true;
+}
+
+bool BookMetadataCache::endWrite() {
+  if (!buildMode) {
+    Serial.printf("[%lu] [BMC] endWrite called but not in build mode\n", millis());
+    return false;
+  }
+
+  buildMode = false;
+  Serial.printf("[%lu] [BMC] Wrote %d spine, %d TOC entries\n", millis(), spineCount, tocCount);
+  return true;
+}
+
+bool BookMetadataCache::buildBookBin(const std::string& epubPath, const BookMetadata& metadata) {
+  // Open all three files, writing to meta, reading from spine and toc
+  if (!FsHelpers::openFileForWrite("BMC", cachePath + bookBinFile, bookFile)) {
+    return false;
+  }
+
+  if (!FsHelpers::openFileForRead("BMC", cachePath + tmpSpineBinFile, spineFile)) {
+    bookFile.close();
+    return false;
+  }
+
+  if (!FsHelpers::openFileForRead("BMC", cachePath + tmpTocBinFile, tocFile)) {
+    bookFile.close();
+    spineFile.close();
+    return false;
+  }
+
+  constexpr size_t headerASize =
+      sizeof(BOOK_CACHE_VERSION) + /* LUT Offset */ sizeof(size_t) + sizeof(spineCount) + sizeof(tocCount);
+  const size_t metadataSize =
+      metadata.title.size() + metadata.author.size() + metadata.coverItemHref.size() + sizeof(uint32_t) * 3;
+  const size_t lutSize = sizeof(size_t) * spineCount + sizeof(size_t) * tocCount;
+  const size_t lutOffset = headerASize + metadataSize;
+
+  // Header A
+  serialization::writePod(bookFile, BOOK_CACHE_VERSION);
+  serialization::writePod(bookFile, lutOffset);
+  serialization::writePod(bookFile, spineCount);
+  serialization::writePod(bookFile, tocCount);
+  // Metadata
+  serialization::writeString(bookFile, metadata.title);
+  serialization::writeString(bookFile, metadata.author);
+  serialization::writeString(bookFile, metadata.coverItemHref);
+
+  // Loop through spine entries, writing LUT positions
+  spineFile.seek(0);
+  for (int i = 0; i < spineCount; i++) {
+    auto pos = spineFile.position();
+    auto spineEntry = readSpineEntry(spineFile);
+    serialization::writePod(bookFile, pos + lutOffset + lutSize);
+  }
+
+  // Loop through toc entries, writing LUT positions
+  tocFile.seek(0);
+  for (int i = 0; i < tocCount; i++) {
+    auto pos = tocFile.position();
+    auto tocEntry = readTocEntry(tocFile);
+    serialization::writePod(bookFile, pos + lutOffset + lutSize + spineFile.position());
+  }
+
+  // LUTs complete
+  // Loop through spines from spine file matching up TOC indexes, calculating cumulative size and writing to book.bin
+
+  const ZipFile zip("/sd" + epubPath);
+  size_t cumSize = 0;
+  spineFile.seek(0);
+  for (int i = 0; i < spineCount; i++) {
+    auto spineEntry = readSpineEntry(spineFile);
+
+    tocFile.seek(0);
+    for (int j = 0; j < tocCount; j++) {
+      auto tocEntry = readTocEntry(tocFile);
+      if (tocEntry.spineIndex == i) {
+        spineEntry.tocIndex = j;
+        break;
+      }
+    }
+
+    // Not a huge deal if we don't fine a TOC entry for the spine entry, this is expected behaviour for EPUBs
+    // Logging here is for debugging
+    if (spineEntry.tocIndex == -1) {
+      Serial.printf("[%lu] [BMC] Warning: Could not find TOC entry for spine item %d: %s\n", millis(), i,
+                    spineEntry.href.c_str());
+    }
+
+    // Calculate size for cumulative size
+    size_t itemSize = 0;
+    const std::string path = FsHelpers::normalisePath(spineEntry.href);
+    if (zip.getInflatedFileSize(path.c_str(), &itemSize)) {
+      cumSize += itemSize;
+      spineEntry.cumulativeSize = cumSize;
+    } else {
+      Serial.printf("[%lu] [BMC] Warning: Could not get size for spine item: %s\n", millis(), path.c_str());
+    }
+
+    // Write out spine data to book.bin
+    writeSpineEntry(bookFile, spineEntry);
+  }
+
+  // Loop through toc entries from toc file writing to book.bin
+  tocFile.seek(0);
+  for (int i = 0; i < tocCount; i++) {
+    auto tocEntry = readTocEntry(tocFile);
+    writeTocEntry(bookFile, tocEntry);
+  }
+
+  bookFile.close();
+  spineFile.close();
+  tocFile.close();
+
+  Serial.printf("[%lu] [BMC] Successfully built book.bin\n", millis());
+  return true;
+}
+
+bool BookMetadataCache::cleanupTmpFiles() const {
+  if (SD.exists((cachePath + tmpSpineBinFile).c_str())) {
+    SD.remove((cachePath + tmpSpineBinFile).c_str());
+  }
+  if (SD.exists((cachePath + tmpTocBinFile).c_str())) {
+    SD.remove((cachePath + tmpTocBinFile).c_str());
+  }
+  return true;
+}
+
+size_t BookMetadataCache::writeSpineEntry(File& file, const SpineEntry& entry) const {
+  const auto pos = file.position();
+  serialization::writeString(file, entry.href);
+  serialization::writePod(file, entry.cumulativeSize);
+  serialization::writePod(file, entry.tocIndex);
+  return pos;
+}
+
+size_t BookMetadataCache::writeTocEntry(File& file, const TocEntry& entry) const {
+  const auto pos = file.position();
+  serialization::writeString(file, entry.title);
+  serialization::writeString(file, entry.href);
+  serialization::writeString(file, entry.anchor);
+  serialization::writePod(file, entry.level);
+  serialization::writePod(file, entry.spineIndex);
+  return pos;
+}
+
+// Note: for the LUT to be accurate, this **MUST** be called for all spine items before `addTocEntry` is ever called
+// this is because in this function we're marking positions of the items
+void BookMetadataCache::createSpineEntry(const std::string& href) {
+  if (!buildMode || !spineFile) {
+    Serial.printf("[%lu] [BMC] createSpineEntry called but not in build mode\n", millis());
+    return;
+  }
+
+  const SpineEntry entry(href, 0, -1);
+  writeSpineEntry(spineFile, entry);
+  spineCount++;
+}
+
+void BookMetadataCache::createTocEntry(const std::string& title, const std::string& href, const std::string& anchor,
+                                       const uint8_t level) {
+  if (!buildMode || !tocFile || !spineFile) {
+    Serial.printf("[%lu] [BMC] createTocEntry called but not in build mode\n", millis());
+    return;
+  }
+
+  int spineIndex = -1;
+  // find spine index
+  spineFile.seek(0);
+  for (int i = 0; i < spineCount; i++) {
+    auto spineEntry = readSpineEntry(spineFile);
+    if (spineEntry.href == href) {
+      spineIndex = i;
+      break;
+    }
+  }
+
+  if (spineIndex == -1) {
+    Serial.printf("[%lu] [BMC] addTocEntry: Could not find spine item for TOC href %s\n", millis(), href.c_str());
+  }
+
+  const TocEntry entry(title, href, anchor, level, spineIndex);
+  writeTocEntry(tocFile, entry);
+  tocCount++;
+}
+
+/* ============= READING / LOADING FUNCTIONS ================ */
+
+bool BookMetadataCache::load() {
+  if (!FsHelpers::openFileForRead("BMC", cachePath + bookBinFile, bookFile)) {
+    return false;
+  }
+
+  uint8_t version;
+  serialization::readPod(bookFile, version);
+  if (version != BOOK_CACHE_VERSION) {
+    Serial.printf("[%lu] [BMC] Cache version mismatch: expected %d, got %d\n", millis(), BOOK_CACHE_VERSION, version);
+    bookFile.close();
+    return false;
+  }
+
+  serialization::readPod(bookFile, lutOffset);
+  serialization::readPod(bookFile, spineCount);
+  serialization::readPod(bookFile, tocCount);
+
+  serialization::readString(bookFile, coreMetadata.title);
+  serialization::readString(bookFile, coreMetadata.author);
+  serialization::readString(bookFile, coreMetadata.coverItemHref);
+
+  loaded = true;
+  Serial.printf("[%lu] [BMC] Loaded cache data: %d spine, %d TOC entries\n", millis(), spineCount, tocCount);
+  return true;
+}
+
+BookMetadataCache::SpineEntry BookMetadataCache::getSpineEntry(const int index) {
+  if (!loaded) {
+    Serial.printf("[%lu] [BMC] getSpineEntry called but cache not loaded\n", millis());
+    return {};
+  }
+
+  if (index < 0 || index >= static_cast<int>(spineCount)) {
+    Serial.printf("[%lu] [BMC] getSpineEntry index %d out of range\n", millis(), index);
+    return {};
+  }
+
+  // Seek to spine LUT item, read from LUT and get out data
+  bookFile.seek(lutOffset + sizeof(size_t) * index);
+  size_t spineEntryPos;
+  serialization::readPod(bookFile, spineEntryPos);
+  bookFile.seek(spineEntryPos);
+  return readSpineEntry(bookFile);
+}
+
+BookMetadataCache::TocEntry BookMetadataCache::getTocEntry(const int index) {
+  if (!loaded) {
+    Serial.printf("[%lu] [BMC] getTocEntry called but cache not loaded\n", millis());
+    return {};
+  }
+
+  if (index < 0 || index >= static_cast<int>(tocCount)) {
+    Serial.printf("[%lu] [BMC] getTocEntry index %d out of range\n", millis(), index);
+    return {};
+  }
+
+  // Seek to TOC LUT item, read from LUT and get out data
+  bookFile.seek(lutOffset + sizeof(size_t) * spineCount + sizeof(size_t) * index);
+  size_t tocEntryPos;
+  serialization::readPod(bookFile, tocEntryPos);
+  bookFile.seek(tocEntryPos);
+  return readTocEntry(bookFile);
+}
+
+BookMetadataCache::SpineEntry BookMetadataCache::readSpineEntry(File& file) const {
+  SpineEntry entry;
+  serialization::readString(file, entry.href);
+  serialization::readPod(file, entry.cumulativeSize);
+  serialization::readPod(file, entry.tocIndex);
+  return entry;
+}
+
+BookMetadataCache::TocEntry BookMetadataCache::readTocEntry(File& file) const {
+  TocEntry entry;
+  serialization::readString(file, entry.title);
+  serialization::readString(file, entry.href);
+  serialization::readString(file, entry.anchor);
+  serialization::readPod(file, entry.level);
+  serialization::readPod(file, entry.spineIndex);
+  return entry;
+}

lib/Epub/Epub/BookMetadataCache.h

@@ -0,0 +1,87 @@
+#pragma once
+
+#include <SD.h>
+
+#include <string>
+
+class BookMetadataCache {
+ public:
+  struct BookMetadata {
+    std::string title;
+    std::string author;
+    std::string coverItemHref;
+  };
+
+  struct SpineEntry {
+    std::string href;
+    size_t cumulativeSize;
+    int16_t tocIndex;
+
+    SpineEntry() : cumulativeSize(0), tocIndex(-1) {}
+    SpineEntry(std::string href, const size_t cumulativeSize, const int16_t tocIndex)
+        : href(std::move(href)), cumulativeSize(cumulativeSize), tocIndex(tocIndex) {}
+  };
+
+  struct TocEntry {
+    std::string title;
+    std::string href;
+    std::string anchor;
+    uint8_t level;
+    int16_t spineIndex;
+
+    TocEntry() : level(0), spineIndex(-1) {}
+    TocEntry(std::string title, std::string href, std::string anchor, const uint8_t level, const int16_t spineIndex)
+        : title(std::move(title)),
+          href(std::move(href)),
+          anchor(std::move(anchor)),
+          level(level),
+          spineIndex(spineIndex) {}
+  };
+
+ private:
+  std::string cachePath;
+  size_t lutOffset;
+  uint16_t spineCount;
+  uint16_t tocCount;
+  bool loaded;
+  bool buildMode;
+
+  File bookFile;
+  // Temp file handles during build
+  File spineFile;
+  File tocFile;
+
+  size_t writeSpineEntry(File& file, const SpineEntry& entry) const;
+  size_t writeTocEntry(File& file, const TocEntry& entry) const;
+  SpineEntry readSpineEntry(File& file) const;
+  TocEntry readTocEntry(File& file) const;
+
+ public:
+  BookMetadata coreMetadata;
+
+  explicit BookMetadataCache(std::string cachePath)
+      : cachePath(std::move(cachePath)), lutOffset(0), spineCount(0), tocCount(0), loaded(false), buildMode(false) {}
+  ~BookMetadataCache() = default;
+
+  // Building phase (stream to disk immediately)
+  bool beginWrite();
+  bool beginContentOpfPass();
+  void createSpineEntry(const std::string& href);
+  bool endContentOpfPass();
+  bool beginTocPass();
+  void createTocEntry(const std::string& title, const std::string& href, const std::string& anchor, uint8_t level);
+  bool endTocPass();
+  bool endWrite();
+  bool cleanupTmpFiles() const;
+
+  // Post-processing to update mappings and sizes
+  bool buildBookBin(const std::string& epubPath, const BookMetadata& metadata);
+
+  // Reading phase (read mode)
+  bool load();
+  SpineEntry getSpineEntry(int index);
+  TocEntry getTocEntry(int index);
+  int getSpineCount() const { return spineCount; }
+  int getTocCount() const { return tocCount; }
+  bool isLoaded() const { return loaded; }
+};

lib/Epub/Epub/EpubTocEntry.h

@@ -1,10 +0,0 @@
-#pragma once
-
-#include <string>
-
-struct EpubTocEntry {
-  std::string title;
-  std::string href;
-  std::string anchor;
-  uint8_t level;
-};

lib/Epub/Epub/FsHelpers.cpp

@@ -2,6 +2,26 @@
 
 #include <SD.h>
 
+#include <vector>
+
+bool FsHelpers::openFileForRead(const char* moduleName, const std::string& path, File& file) {
+  file = SD.open(path.c_str(), FILE_READ);
+  if (!file) {
+    Serial.printf("[%lu] [%s] Failed to open file for reading: %s\n", millis(), moduleName, path.c_str());
+    return false;
+  }
+  return true;
+}
+
+bool FsHelpers::openFileForWrite(const char* moduleName, const std::string& path, File& file) {
+  file = SD.open(path.c_str(), FILE_WRITE, true);
+  if (!file) {
+    Serial.printf("[%lu] [%s] Failed to open file for writing: %s\n", millis(), moduleName, path.c_str());
+    return false;
+  }
+  return true;
+}
+
 bool FsHelpers::removeDir(const char* path) {
   // 1. Open the directory
   File dir = SD.open(path);
@@ -34,3 +54,39 @@ bool FsHelpers::removeDir(const char* path) {
 
   return SD.rmdir(path);
 }
+
+std::string FsHelpers::normalisePath(const std::string& path) {
+  std::vector<std::string> components;
+  std::string component;
+
+  for (const auto c : path) {
+    if (c == '/') {
+      if (!component.empty()) {
+        if (component == "..") {
+          if (!components.empty()) {
+            components.pop_back();
+          }
+        } else {
+          components.push_back(component);
+        }
+        component.clear();
+      }
+    } else {
+      component += c;
+    }
+  }
+
+  if (!component.empty()) {
+    components.push_back(component);
+  }
+
+  std::string result;
+  for (const auto& c : components) {
+    if (!result.empty()) {
+      result += "/";
+    }
+    result += c;
+  }
+
+  return result;
+}

lib/Epub/Epub/FsHelpers.h

@@ -1,6 +1,12 @@
 #pragma once
+#include <FS.h>
+
+#include <string>
 
 class FsHelpers {
  public:
+  static bool openFileForRead(const char* moduleName, const std::string& path, File& file);
+  static bool openFileForWrite(const char* moduleName, const std::string& path, File& file);
   static bool removeDir(const char* path);
+  static std::string normalisePath(const std::string& path);
 };

lib/Epub/Epub/Page.cpp

@@ -9,21 +9,21 @@ constexpr uint8_t PAGE_FILE_VERSION = 3;
 
 void PageLine::render(GfxRenderer& renderer, const int fontId) { block->render(renderer, fontId, xPos, yPos); }
 
-void PageLine::serialize(std::ostream& os) {
-  serialization::writePod(os, xPos);
-  serialization::writePod(os, yPos);
+void PageLine::serialize(File& file) {
+  serialization::writePod(file, xPos);
+  serialization::writePod(file, yPos);
 
   // serialize TextBlock pointed to by PageLine
-  block->serialize(os);
+  block->serialize(file);
 }
 
-std::unique_ptr<PageLine> PageLine::deserialize(std::istream& is) {
+std::unique_ptr<PageLine> PageLine::deserialize(File& file) {
   int16_t xPos;
   int16_t yPos;
-  serialization::readPod(is, xPos);
-  serialization::readPod(is, yPos);
+  serialization::readPod(file, xPos);
+  serialization::readPod(file, yPos);
 
-  auto tb = TextBlock::deserialize(is);
+  auto tb = TextBlock::deserialize(file);
   return std::unique_ptr<PageLine>(new PageLine(std::move(tb), xPos, yPos));
 }
 
@@ -33,22 +33,22 @@ void Page::render(GfxRenderer& renderer, const int fontId) const {
   }
 }
 
-void Page::serialize(std::ostream& os) const {
-  serialization::writePod(os, PAGE_FILE_VERSION);
+void Page::serialize(File& file) const {
+  serialization::writePod(file, PAGE_FILE_VERSION);
 
   const uint32_t count = elements.size();
-  serialization::writePod(os, count);
+  serialization::writePod(file, count);
 
   for (const auto& el : elements) {
     // Only PageLine exists currently
-    serialization::writePod(os, static_cast<uint8_t>(TAG_PageLine));
-    el->serialize(os);
+    serialization::writePod(file, static_cast<uint8_t>(TAG_PageLine));
+    el->serialize(file);
   }
 }
 
-std::unique_ptr<Page> Page::deserialize(std::istream& is) {
+std::unique_ptr<Page> Page::deserialize(File& file) {
   uint8_t version;
-  serialization::readPod(is, version);
+  serialization::readPod(file, version);
   if (version != PAGE_FILE_VERSION) {
     Serial.printf("[%lu] [PGE] Deserialization failed: Unknown version %u\n", millis(), version);
     return nullptr;
@@ -57,14 +57,14 @@ std::unique_ptr<Page> Page::deserialize(std::istream& is) {
   auto page = std::unique_ptr<Page>(new Page());
 
   uint32_t count;
-  serialization::readPod(is, count);
+  serialization::readPod(file, count);
 
   for (uint32_t i = 0; i < count; i++) {
     uint8_t tag;
-    serialization::readPod(is, tag);
+    serialization::readPod(file, tag);
 
     if (tag == TAG_PageLine) {
-      auto pl = PageLine::deserialize(is);
+      auto pl = PageLine::deserialize(file);
       page->elements.push_back(std::move(pl));
     } else {
       Serial.printf("[%lu] [PGE] Deserialization failed: Unknown tag %u\n", millis(), tag);

lib/Epub/Epub/Page.h

@@ -1,4 +1,6 @@
 #pragma once
+#include <FS.h>
+
 #include <utility>
 #include <vector>
 
@@ -16,7 +18,7 @@ class PageElement {
   explicit PageElement(const int16_t xPos, const int16_t yPos) : xPos(xPos), yPos(yPos) {}
   virtual ~PageElement() = default;
   virtual void render(GfxRenderer& renderer, int fontId) = 0;
-  virtual void serialize(std::ostream& os) = 0;
+  virtual void serialize(File& file) = 0;
 };
 
 // a line from a block element
@@ -27,8 +29,8 @@ class PageLine final : public PageElement {
   PageLine(std::shared_ptr<TextBlock> block, const int16_t xPos, const int16_t yPos)
       : PageElement(xPos, yPos), block(std::move(block)) {}
   void render(GfxRenderer& renderer, int fontId) override;
-  void serialize(std::ostream& os) override;
-  static std::unique_ptr<PageLine> deserialize(std::istream& is);
+  void serialize(File& file) override;
+  static std::unique_ptr<PageLine> deserialize(File& file);
 };
 
 class Page {
@@ -36,6 +38,6 @@ class Page {
   // the list of block index and line numbers on this page
   std::vector<std::shared_ptr<PageElement>> elements;
   void render(GfxRenderer& renderer, int fontId) const;
-  void serialize(std::ostream& os) const;
-  static std::unique_ptr<Page> deserialize(std::istream& is);
+  void serialize(File& file) const;
+  static std::unique_ptr<Page> deserialize(File& file);
 };

lib/Epub/Epub/Section.cpp

@@ -1,11 +1,9 @@
 #include "Section.h"
 
+#include <FsHelpers.h>
 #include <SD.h>
 #include <Serialization.h>
 
-#include <fstream>
-
-#include "FsHelpers.h"
 #include "Page.h"
 #include "parsers/ChapterHtmlSlimParser.h"
 
@@ -16,7 +14,10 @@ constexpr uint8_t SECTION_FILE_VERSION = 5;
 void Section::onPageComplete(std::unique_ptr<Page> page) {
   const auto filePath = cachePath + "/page_" + std::to_string(pageCount) + ".bin";
 
-  std::ofstream outputFile("/sd" + filePath);
+  File outputFile;
+  if (!FsHelpers::openFileForWrite("SCT", filePath, outputFile)) {
+    return;
+  }
   page->serialize(outputFile);
   outputFile.close();
 
@@ -28,7 +29,10 @@ void Section::onPageComplete(std::unique_ptr<Page> page) {
 void Section::writeCacheMetadata(const int fontId, const float lineCompression, const int marginTop,
                                  const int marginRight, const int marginBottom, const int marginLeft,
                                  const bool extraParagraphSpacing) const {
-  std::ofstream outputFile(("/sd" + cachePath + "/section.bin").c_str());
+  File outputFile;
+  if (!FsHelpers::openFileForWrite("SCT", cachePath + "/section.bin", outputFile)) {
+    return;
+  }
   serialization::writePod(outputFile, SECTION_FILE_VERSION);
   serialization::writePod(outputFile, fontId);
   serialization::writePod(outputFile, lineCompression);
@@ -44,17 +48,12 @@ void Section::writeCacheMetadata(const int fontId, const float lineCompression,
 bool Section::loadCacheMetadata(const int fontId, const float lineCompression, const int marginTop,
                                 const int marginRight, const int marginBottom, const int marginLeft,
                                 const bool extraParagraphSpacing) {
-  if (!SD.exists(cachePath.c_str())) {
-    return false;
-  }
-
   const auto sectionFilePath = cachePath + "/section.bin";
-  if (!SD.exists(sectionFilePath.c_str())) {
+  File inputFile;
+  if (!FsHelpers::openFileForRead("SCT", sectionFilePath, inputFile)) {
     return false;
   }
 
-  std::ifstream inputFile(("/sd" + sectionFilePath).c_str());
-
   // Match parameters
   {
     uint8_t version;
@@ -117,15 +116,14 @@ bool Section::clearCache() const {
 bool Section::persistPageDataToSD(const int fontId, const float lineCompression, const int marginTop,
                                   const int marginRight, const int marginBottom, const int marginLeft,
                                   const bool extraParagraphSpacing) {
-  const auto localPath = epub->getSpineItem(spineIndex);
-
-  // TODO: Should we get rid of this file all together?
-  //       It currently saves us a bit of memory by allowing for all the inflation bits to be released
-  //       before loading the XML parser
+  const auto localPath = epub->getSpineItem(spineIndex).href;
   const auto tmpHtmlPath = epub->getCachePath() + "/.tmp_" + std::to_string(spineIndex) + ".html";
-  File f = SD.open(tmpHtmlPath.c_str(), FILE_WRITE, true);
-  bool success = epub->readItemContentsToStream(localPath, f, 1024);
-  f.close();
+  File tmpHtml;
+  if (!FsHelpers::openFileForWrite("SCT", tmpHtmlPath, tmpHtml)) {
+    return false;
+  }
+  bool success = epub->readItemContentsToStream(localPath, tmpHtml, 1024);
+  tmpHtml.close();
 
   if (!success) {
     Serial.printf("[%lu] [SCT] Failed to stream item contents to temp file\n", millis());
@@ -134,10 +132,8 @@ bool Section::persistPageDataToSD(const int fontId, const float lineCompression,
 
   Serial.printf("[%lu] [SCT] Streamed temp HTML to %s\n", millis(), tmpHtmlPath.c_str());
 
-  const auto sdTmpHtmlPath = "/sd" + tmpHtmlPath;
-
-  ChapterHtmlSlimParser visitor(sdTmpHtmlPath.c_str(), renderer, fontId, lineCompression, marginTop, marginRight,
-                                marginBottom, marginLeft, extraParagraphSpacing,
+  ChapterHtmlSlimParser visitor(tmpHtmlPath, renderer, fontId, lineCompression, marginTop, marginRight, marginBottom,
+                                marginLeft, extraParagraphSpacing,
                                 [this](std::unique_ptr<Page> page) { this->onPageComplete(std::move(page)); });
   success = visitor.parseAndBuildPages();
 
@@ -153,13 +149,12 @@ bool Section::persistPageDataToSD(const int fontId, const float lineCompression,
 }
 
 std::unique_ptr<Page> Section::loadPageFromSD() const {
-  const auto filePath = "/sd" + cachePath + "/page_" + std::to_string(currentPage) + ".bin";
-  if (!SD.exists(filePath.c_str() + 3)) {
-    Serial.printf("[%lu] [SCT] Page file does not exist: %s\n", millis(), filePath.c_str());
+  const auto filePath = cachePath + "/page_" + std::to_string(currentPage) + ".bin";
+
+  File inputFile;
+  if (!FsHelpers::openFileForRead("SCT", filePath, inputFile)) {
     return nullptr;
   }
-
-  std::ifstream inputFile(filePath);
   auto page = Page::deserialize(inputFile);
   inputFile.close();
   return page;

lib/Epub/Epub/blocks/TextBlock.cpp

@@ -17,27 +17,27 @@ void TextBlock::render(const GfxRenderer& renderer, const int fontId, const int
   }
 }
 
-void TextBlock::serialize(std::ostream& os) const {
+void TextBlock::serialize(File& file) const {
   // words
   const uint32_t wc = words.size();
-  serialization::writePod(os, wc);
-  for (const auto& w : words) serialization::writeString(os, w);
+  serialization::writePod(file, wc);
+  for (const auto& w : words) serialization::writeString(file, w);
 
   // wordXpos
   const uint32_t xc = wordXpos.size();
-  serialization::writePod(os, xc);
-  for (auto x : wordXpos) serialization::writePod(os, x);
+  serialization::writePod(file, xc);
+  for (auto x : wordXpos) serialization::writePod(file, x);
 
   // wordStyles
   const uint32_t sc = wordStyles.size();
-  serialization::writePod(os, sc);
-  for (auto s : wordStyles) serialization::writePod(os, s);
+  serialization::writePod(file, sc);
+  for (auto s : wordStyles) serialization::writePod(file, s);
 
   // style
-  serialization::writePod(os, style);
+  serialization::writePod(file, style);
 }
 
-std::unique_ptr<TextBlock> TextBlock::deserialize(std::istream& is) {
+std::unique_ptr<TextBlock> TextBlock::deserialize(File& file) {
   uint32_t wc, xc, sc;
   std::list<std::string> words;
   std::list<uint16_t> wordXpos;
@@ -45,22 +45,22 @@ std::unique_ptr<TextBlock> TextBlock::deserialize(std::istream& is) {
   BLOCK_STYLE style;
 
   // words
-  serialization::readPod(is, wc);
+  serialization::readPod(file, wc);
   words.resize(wc);
-  for (auto& w : words) serialization::readString(is, w);
+  for (auto& w : words) serialization::readString(file, w);
 
   // wordXpos
-  serialization::readPod(is, xc);
+  serialization::readPod(file, xc);
   wordXpos.resize(xc);
-  for (auto& x : wordXpos) serialization::readPod(is, x);
+  for (auto& x : wordXpos) serialization::readPod(file, x);
 
   // wordStyles
-  serialization::readPod(is, sc);
+  serialization::readPod(file, sc);
   wordStyles.resize(sc);
-  for (auto& s : wordStyles) serialization::readPod(is, s);
+  for (auto& s : wordStyles) serialization::readPod(file, s);
 
   // style
-  serialization::readPod(is, style);
+  serialization::readPod(file, style);
 
   return std::unique_ptr<TextBlock>(new TextBlock(std::move(words), std::move(wordXpos), std::move(wordStyles), style));
 }

lib/Epub/Epub/blocks/TextBlock.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <EpdFontFamily.h>
+#include <FS.h>
 
 #include <list>
 #include <memory>
@@ -35,6 +36,6 @@ class TextBlock final : public Block {
   // given a renderer works out where to break the words into lines
   void render(const GfxRenderer& renderer, int fontId, int x, int y) const;
   BlockType getType() override { return TEXT_BLOCK; }
-  void serialize(std::ostream& os) const;
-  static std::unique_ptr<TextBlock> deserialize(std::istream& is);
+  void serialize(File& file) const;
+  static std::unique_ptr<TextBlock> deserialize(File& file);
 };

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -1,5 +1,6 @@
 #include "ChapterHtmlSlimParser.h"
 
+#include <FsHelpers.h>
 #include <GfxRenderer.h>
 #include <HardwareSerial.h>
 #include <expat.h>
@@ -10,13 +11,13 @@
 const char* HEADER_TAGS[] = {"h1", "h2", "h3", "h4", "h5", "h6"};
 constexpr int NUM_HEADER_TAGS = sizeof(HEADER_TAGS) / sizeof(HEADER_TAGS[0]);
 
-const char* BLOCK_TAGS[] = {"p", "li", "div", "br"};
+const char* BLOCK_TAGS[] = {"p", "li", "div", "br", "blockquote"};
 constexpr int NUM_BLOCK_TAGS = sizeof(BLOCK_TAGS) / sizeof(BLOCK_TAGS[0]);
 
-const char* BOLD_TAGS[] = {"b"};
+const char* BOLD_TAGS[] = {"b", "strong"};
 constexpr int NUM_BOLD_TAGS = sizeof(BOLD_TAGS) / sizeof(BOLD_TAGS[0]);
 
-const char* ITALIC_TAGS[] = {"i"};
+const char* ITALIC_TAGS[] = {"i", "em"};
 constexpr int NUM_ITALIC_TAGS = sizeof(ITALIC_TAGS) / sizeof(ITALIC_TAGS[0]);
 
 const char* IMAGE_TAGS[] = {"img"};
@@ -214,48 +215,59 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
     return false;
   }
 
-  XML_SetUserData(parser, this);
-  XML_SetElementHandler(parser, startElement, endElement);
-  XML_SetCharacterDataHandler(parser, characterData);
-
-  FILE* file = fopen(filepath, "r");
-  if (!file) {
-    Serial.printf("[%lu] [EHP] Couldn't open file %s\n", millis(), filepath);
+  File file;
+  if (!FsHelpers::openFileForRead("EHP", filepath, file)) {
     XML_ParserFree(parser);
     return false;
   }
 
+  XML_SetUserData(parser, this);
+  XML_SetElementHandler(parser, startElement, endElement);
+  XML_SetCharacterDataHandler(parser, characterData);
+
   do {
     void* const buf = XML_GetBuffer(parser, 1024);
     if (!buf) {
       Serial.printf("[%lu] [EHP] Couldn't allocate memory for buffer\n", millis());
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      fclose(file);
+      file.close();
       return false;
     }
 
-    const size_t len = fread(buf, 1, 1024, file);
+    const size_t len = file.read(static_cast<uint8_t*>(buf), 1024);
 
-    if (ferror(file)) {
+    if (len == 0) {
       Serial.printf("[%lu] [EHP] File read error\n", millis());
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      fclose(file);
+      file.close();
       return false;
     }
 
-    done = feof(file);
+    done = file.available() == 0;
 
     if (XML_ParseBuffer(parser, static_cast<int>(len), done) == XML_STATUS_ERROR) {
       Serial.printf("[%lu] [EHP] Parse error at line %lu:\n%s\n", millis(), XML_GetCurrentLineNumber(parser),
                     XML_ErrorString(XML_GetErrorCode(parser)));
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      fclose(file);
+      file.close();
       return false;
     }
   } while (!done);
 
+  XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+  XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+  XML_SetCharacterDataHandler(parser, nullptr);
   XML_ParserFree(parser);
-  fclose(file);
+  file.close();
 
   // Process last page if there is still text
   if (currentTextBlock) {

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.h

@@ -15,7 +15,7 @@ class GfxRenderer;
 #define MAX_WORD_SIZE 200
 
 class ChapterHtmlSlimParser {
-  const char* filepath;
+  const std::string& filepath;
   GfxRenderer& renderer;
   std::function<void(std::unique_ptr<Page>)> completePageFn;
   int depth = 0;
@@ -45,7 +45,7 @@ class ChapterHtmlSlimParser {
   static void XMLCALL endElement(void* userData, const XML_Char* name);
 
  public:
-  explicit ChapterHtmlSlimParser(const char* filepath, GfxRenderer& renderer, const int fontId,
+  explicit ChapterHtmlSlimParser(const std::string& filepath, GfxRenderer& renderer, const int fontId,
                                  const float lineCompression, const int marginTop, const int marginRight,
                                  const int marginBottom, const int marginLeft, const bool extraParagraphSpacing,
                                  const std::function<void(std::unique_ptr<Page>)>& completePageFn)

lib/Epub/Epub/parsers/ContainerParser.cpp

@@ -16,6 +16,8 @@ bool ContainerParser::setup() {
 
 ContainerParser::~ContainerParser() {
   if (parser) {
+    XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+    XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
     XML_ParserFree(parser);
     parser = nullptr;
   }

lib/Epub/Epub/parsers/ContentOpfParser.cpp

@@ -1,11 +1,16 @@
 #include "ContentOpfParser.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
+#include <Serialization.h>
 #include <ZipFile.h>
 
+#include "../BookMetadataCache.h"
+
 namespace {
 constexpr char MEDIA_TYPE_NCX[] = "application/x-dtbncx+xml";
-}
+constexpr char itemCacheFile[] = "/.items.bin";
+}  // namespace
 
 bool ContentOpfParser::setup() {
   parser = XML_ParserCreate(nullptr);
@@ -22,9 +27,18 @@ bool ContentOpfParser::setup() {
 
 ContentOpfParser::~ContentOpfParser() {
   if (parser) {
+    XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+    XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+    XML_SetCharacterDataHandler(parser, nullptr);
     XML_ParserFree(parser);
     parser = nullptr;
   }
+  if (tempItemStore) {
+    tempItemStore.close();
+  }
+  if (SD.exists((cachePath + itemCacheFile).c_str())) {
+    SD.remove((cachePath + itemCacheFile).c_str());
+  }
 }
 
 size_t ContentOpfParser::write(const uint8_t data) { return write(&data, 1); }
@@ -40,6 +54,9 @@ size_t ContentOpfParser::write(const uint8_t* buffer, const size_t size) {
 
     if (!buf) {
       Serial.printf("[%lu] [COF] Couldn't allocate memory for buffer\n", millis());
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
       parser = nullptr;
       return 0;
@@ -51,6 +68,9 @@ size_t ContentOpfParser::write(const uint8_t* buffer, const size_t size) {
     if (XML_ParseBuffer(parser, static_cast<int>(toRead), remainingSize == toRead) == XML_STATUS_ERROR) {
       Serial.printf("[%lu] [COF] Parse error at line %lu: %s\n", millis(), XML_GetCurrentLineNumber(parser),
                     XML_ErrorString(XML_GetErrorCode(parser)));
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
       parser = nullptr;
       return 0;
@@ -85,11 +105,21 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
 
   if (self->state == IN_PACKAGE && (strcmp(name, "manifest") == 0 || strcmp(name, "opf:manifest") == 0)) {
     self->state = IN_MANIFEST;
+    if (!FsHelpers::openFileForWrite("COF", self->cachePath + itemCacheFile, self->tempItemStore)) {
+      Serial.printf(
+          "[%lu] [COF] Couldn't open temp items file for writing. This is probably going to be a fatal error.\n",
+          millis());
+    }
     return;
   }
 
   if (self->state == IN_PACKAGE && (strcmp(name, "spine") == 0 || strcmp(name, "opf:spine") == 0)) {
     self->state = IN_SPINE;
+    if (!FsHelpers::openFileForRead("COF", self->cachePath + itemCacheFile, self->tempItemStore)) {
+      Serial.printf(
+          "[%lu] [COF] Couldn't open temp items file for reading. This is probably going to be a fatal error.\n",
+          millis());
+    }
     return;
   }
 
@@ -126,7 +156,13 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
       }
     }
 
-    self->items[itemId] = href;
+    // Write items down to SD card
+    serialization::writeString(self->tempItemStore, itemId);
+    serialization::writeString(self->tempItemStore, href);
+
+    if (itemId == self->coverItemId) {
+      self->coverItemHref = href;
+    }
 
     if (mediaType == MEDIA_TYPE_NCX) {
       if (self->tocNcxPath.empty()) {
@@ -139,15 +175,30 @@ void XMLCALL ContentOpfParser::startElement(void* userData, const XML_Char* name
     return;
   }
 
+  // NOTE: This relies on spine appearing after item manifest (which is pretty safe as it's part of the EPUB spec)
+  // Only run the spine parsing if there's a cache to add it to
+  if (self->cache) {
     if (self->state == IN_SPINE && (strcmp(name, "itemref") == 0 || strcmp(name, "opf:itemref") == 0)) {
       for (int i = 0; atts[i]; i += 2) {
         if (strcmp(atts[i], "idref") == 0) {
-        self->spineRefs.emplace_back(atts[i + 1]);
+          const std::string idref = atts[i + 1];
+          // Resolve the idref to href using items map
+          self->tempItemStore.seek(0);
+          std::string itemId;
+          std::string href;
+          while (self->tempItemStore.available()) {
+            serialization::readString(self->tempItemStore, itemId);
+            serialization::readString(self->tempItemStore, href);
+            if (itemId == idref) {
+              self->cache->createSpineEntry(href);
               break;
             }
           }
+        }
+      }
       return;
     }
+  }
 }
 
 void XMLCALL ContentOpfParser::characterData(void* userData, const XML_Char* s, const int len) {
@@ -165,11 +216,13 @@ void XMLCALL ContentOpfParser::endElement(void* userData, const XML_Char* name)
 
   if (self->state == IN_SPINE && (strcmp(name, "spine") == 0 || strcmp(name, "opf:spine") == 0)) {
     self->state = IN_PACKAGE;
+    self->tempItemStore.close();
     return;
   }
 
   if (self->state == IN_MANIFEST && (strcmp(name, "manifest") == 0 || strcmp(name, "opf:manifest") == 0)) {
     self->state = IN_PACKAGE;
+    self->tempItemStore.close();
     return;
   }
 

lib/Epub/Epub/parsers/ContentOpfParser.h

@@ -1,11 +1,11 @@
 #pragma once
 #include <Print.h>
 
-#include <map>
-
 #include "Epub.h"
 #include "expat.h"
 
+class BookMetadataCache;
+
 class ContentOpfParser final : public Print {
   enum ParserState {
     START,
@@ -16,10 +16,14 @@ class ContentOpfParser final : public Print {
     IN_SPINE,
   };
 
+  const std::string& cachePath;
   const std::string& baseContentPath;
   size_t remainingSize;
   XML_Parser parser = nullptr;
   ParserState state = START;
+  BookMetadataCache* cache;
+  File tempItemStore;
+  std::string coverItemId;
 
   static void startElement(void* userData, const XML_Char* name, const XML_Char** atts);
   static void characterData(void* userData, const XML_Char* s, int len);
@@ -28,12 +32,11 @@ class ContentOpfParser final : public Print {
  public:
   std::string title;
   std::string tocNcxPath;
-  std::string coverItemId;
-  std::map<std::string, std::string> items;
-  std::vector<std::string> spineRefs;
+  std::string coverItemHref;
 
-  explicit ContentOpfParser(const std::string& baseContentPath, const size_t xmlSize)
-      : baseContentPath(baseContentPath), remainingSize(xmlSize) {}
+  explicit ContentOpfParser(const std::string& cachePath, const std::string& baseContentPath, const size_t xmlSize,
+                            BookMetadataCache* cache)
+      : cachePath(cachePath), baseContentPath(baseContentPath), remainingSize(xmlSize), cache(cache) {}
   ~ContentOpfParser() override;
 
   bool setup();

lib/Epub/Epub/parsers/TocNcxParser.cpp

@@ -1,8 +1,9 @@
 #include "TocNcxParser.h"
 
-#include <Esp.h>
 #include <HardwareSerial.h>
 
+#include "../BookMetadataCache.h"
+
 bool TocNcxParser::setup() {
   parser = XML_ParserCreate(nullptr);
   if (!parser) {
@@ -18,6 +19,9 @@ bool TocNcxParser::setup() {
 
 TocNcxParser::~TocNcxParser() {
   if (parser) {
+    XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+    XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+    XML_SetCharacterDataHandler(parser, nullptr);
     XML_ParserFree(parser);
     parser = nullptr;
   }
@@ -35,6 +39,11 @@ size_t TocNcxParser::write(const uint8_t* buffer, const size_t size) {
     void* const buf = XML_GetBuffer(parser, 1024);
     if (!buf) {
       Serial.printf("[%lu] [TOC] Couldn't allocate memory for buffer\n", millis());
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
+      XML_ParserFree(parser);
+      parser = nullptr;
       return 0;
     }
 
@@ -44,6 +53,11 @@ size_t TocNcxParser::write(const uint8_t* buffer, const size_t size) {
     if (XML_ParseBuffer(parser, static_cast<int>(toRead), remainingSize == toRead) == XML_STATUS_ERROR) {
       Serial.printf("[%lu] [TOC] Parse error at line %lu: %s\n", millis(), XML_GetCurrentLineNumber(parser),
                     XML_ErrorString(XML_GetErrorCode(parser)));
+      XML_StopParser(parser, XML_FALSE);                // Stop any pending processing
+      XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
+      XML_SetCharacterDataHandler(parser, nullptr);
+      XML_ParserFree(parser);
+      parser = nullptr;
       return 0;
     }
 
@@ -154,8 +168,9 @@ void XMLCALL TocNcxParser::endElement(void* userData, const XML_Char* name) {
         href = href.substr(0, pos);
       }
 
-      // Push to vector
-      self->toc.push_back({std::move(self->currentLabel), std::move(href), std::move(anchor), self->currentDepth});
+      if (self->cache) {
+        self->cache->createTocEntry(self->currentLabel, href, anchor, self->currentDepth);
+      }
 
       // Clear them so we don't re-add them if there are weird XML structures
       self->currentLabel.clear();

lib/Epub/Epub/parsers/TocNcxParser.h

@@ -1,11 +1,10 @@
 #pragma once
 #include <Print.h>
+#include <expat.h>
 
 #include <string>
-#include <vector>
 
-#include "Epub/EpubTocEntry.h"
-#include "expat.h"
+class BookMetadataCache;
 
 class TocNcxParser final : public Print {
   enum ParserState { START, IN_NCX, IN_NAV_MAP, IN_NAV_POINT, IN_NAV_LABEL, IN_NAV_LABEL_TEXT, IN_CONTENT };
@@ -14,6 +13,7 @@ class TocNcxParser final : public Print {
   size_t remainingSize;
   XML_Parser parser = nullptr;
   ParserState state = START;
+  BookMetadataCache* cache;
 
   std::string currentLabel;
   std::string currentSrc;
@@ -24,10 +24,8 @@ class TocNcxParser final : public Print {
   static void endElement(void* userData, const XML_Char* name);
 
  public:
-  std::vector<EpubTocEntry> toc;
-
-  explicit TocNcxParser(const std::string& baseContentPath, const size_t xmlSize)
-      : baseContentPath(baseContentPath), remainingSize(xmlSize) {}
+  explicit TocNcxParser(const std::string& baseContentPath, const size_t xmlSize, BookMetadataCache* cache)
+      : baseContentPath(baseContentPath), remainingSize(xmlSize), cache(cache) {}
   ~TocNcxParser() override;
 
   bool setup();

lib/FsHelpers/FsHelpers.cpp

@@ -0,0 +1,112 @@
+#include "FsHelpers.h"
+
+#include <SD.h>
+
+#include <vector>
+
+bool FsHelpers::openFileForRead(const char* moduleName, const char* path, File& file) {
+  if (!SD.exists(path)) {
+    return false;
+  }
+
+  file = SD.open(path, FILE_READ);
+  if (!file) {
+    Serial.printf("[%lu] [%s] Failed to open file for reading: %s\n", millis(), moduleName, path);
+    return false;
+  }
+  return true;
+}
+
+bool FsHelpers::openFileForRead(const char* moduleName, const std::string& path, File& file) {
+  return openFileForRead(moduleName, path.c_str(), file);
+}
+
+bool FsHelpers::openFileForRead(const char* moduleName, const String& path, File& file) {
+  return openFileForRead(moduleName, path.c_str(), file);
+}
+
+bool FsHelpers::openFileForWrite(const char* moduleName, const char* path, File& file) {
+  file = SD.open(path, FILE_WRITE, true);
+  if (!file) {
+    Serial.printf("[%lu] [%s] Failed to open file for writing: %s\n", millis(), moduleName, path);
+    return false;
+  }
+  return true;
+}
+
+bool FsHelpers::openFileForWrite(const char* moduleName, const std::string& path, File& file) {
+  return openFileForWrite(moduleName, path.c_str(), file);
+}
+
+bool FsHelpers::openFileForWrite(const char* moduleName, const String& path, File& file) {
+  return openFileForWrite(moduleName, path.c_str(), file);
+}
+
+bool FsHelpers::removeDir(const char* path) {
+  // 1. Open the directory
+  File dir = SD.open(path);
+  if (!dir) {
+    return false;
+  }
+  if (!dir.isDirectory()) {
+    return false;
+  }
+
+  File file = dir.openNextFile();
+  while (file) {
+    String filePath = path;
+    if (!filePath.endsWith("/")) {
+      filePath += "/";
+    }
+    filePath += file.name();
+
+    if (file.isDirectory()) {
+      if (!removeDir(filePath.c_str())) {
+        return false;
+      }
+    } else {
+      if (!SD.remove(filePath.c_str())) {
+        return false;
+      }
+    }
+    file = dir.openNextFile();
+  }
+
+  return SD.rmdir(path);
+}
+
+std::string FsHelpers::normalisePath(const std::string& path) {
+  std::vector<std::string> components;
+  std::string component;
+
+  for (const auto c : path) {
+    if (c == '/') {
+      if (!component.empty()) {
+        if (component == "..") {
+          if (!components.empty()) {
+            components.pop_back();
+          }
+        } else {
+          components.push_back(component);
+        }
+        component.clear();
+      }
+    } else {
+      component += c;
+    }
+  }
+
+  if (!component.empty()) {
+    components.push_back(component);
+  }
+
+  std::string result;
+  for (const auto& c : components) {
+    if (!result.empty()) {
+      result += "/";
+    }
+    result += c;
+  }
+
+  return result;
+}

lib/FsHelpers/FsHelpers.h

@@ -0,0 +1,14 @@
+#pragma once
+#include <FS.h>
+
+class FsHelpers {
+ public:
+  static bool openFileForRead(const char* moduleName, const char* path, File& file);
+  static bool openFileForRead(const char* moduleName, const std::string& path, File& file);
+  static bool openFileForRead(const char* moduleName, const String& path, File& file);
+  static bool openFileForWrite(const char* moduleName, const char* path, File& file);
+  static bool openFileForWrite(const char* moduleName, const std::string& path, File& file);
+  static bool openFileForWrite(const char* moduleName, const String& path, File& file);
+  static bool removeDir(const char* path);
+  static std::string normalisePath(const std::string& path);
+};

lib/JpegToBmpConverter/JpegToBmpConverter.cpp

@@ -182,6 +182,9 @@ bool JpegToBmpConverter::jpegFileToBmpStream(File& jpegFile, Print& bmpOut) {
       }
 
       // Process MCU block into MCU row buffer
+      // MCUs are composed of 8x8 blocks. For 16x16 MCUs, there are four 8x8 blocks:
+      // Block layout for 16x16 MCU:  [0, 64]  (top row of blocks)
+      //                              [128, 192] (bottom row of blocks)
       for (int blockY = 0; blockY < mcuPixelHeight; blockY++) {
         for (int blockX = 0; blockX < mcuPixelWidth; blockX++) {
           const int pixelX = mcuX * mcuPixelWidth + blockX;
@@ -191,16 +194,27 @@ bool JpegToBmpConverter::jpegFileToBmpStream(File& jpegFile, Print& bmpOut) {
             continue;
           }
 
+          // Calculate which 8x8 block and position within that block
+          const int block8x8Col = blockX / 8;  // 0 or 1 for 16-wide MCU
+          const int block8x8Row = blockY / 8;  // 0 or 1 for 16-tall MCU
+          const int pixelInBlockX = blockX % 8;
+          const int pixelInBlockY = blockY % 8;
+
+          // Calculate byte offset: each 8x8 block is 64 bytes
+          // Blocks are arranged: [0, 64], [128, 192]
+          const int blockOffset = (block8x8Row * (mcuPixelWidth / 8) + block8x8Col) * 64;
+          const int mcuIndex = blockOffset + pixelInBlockY * 8 + pixelInBlockX;
+
           // Get grayscale value
           uint8_t gray;
           if (imageInfo.m_comps == 1) {
             // Grayscale image
-            gray = imageInfo.m_pMCUBufR[blockY * mcuPixelWidth + blockX];
+            gray = imageInfo.m_pMCUBufR[mcuIndex];
           } else {
             // RGB image - convert to grayscale
-            const uint8_t r = imageInfo.m_pMCUBufR[blockY * mcuPixelWidth + blockX];
-            const uint8_t g = imageInfo.m_pMCUBufG[blockY * mcuPixelWidth + blockX];
-            const uint8_t b = imageInfo.m_pMCUBufB[blockY * mcuPixelWidth + blockX];
+            const uint8_t r = imageInfo.m_pMCUBufR[mcuIndex];
+            const uint8_t g = imageInfo.m_pMCUBufG[mcuIndex];
+            const uint8_t b = imageInfo.m_pMCUBufB[mcuIndex];
             // Luminance formula: Y = 0.299*R + 0.587*G + 0.114*B
             // Using integer approximation: (30*R + 59*G + 11*B) / 100
             gray = (r * 30 + g * 59 + b * 11) / 100;

lib/Serialization/Serialization.h

@@ -1,4 +1,6 @@
 #pragma once
+#include <FS.h>
+
 #include <iostream>
 
 namespace serialization {
@@ -7,21 +9,44 @@ static void writePod(std::ostream& os, const T& value) {
   os.write(reinterpret_cast<const char*>(&value), sizeof(T));
 }
 
+template <typename T>
+static void writePod(File& file, const T& value) {
+  file.write(reinterpret_cast<const uint8_t*>(&value), sizeof(T));
+}
+
 template <typename T>
 static void readPod(std::istream& is, T& value) {
   is.read(reinterpret_cast<char*>(&value), sizeof(T));
 }
 
+template <typename T>
+static void readPod(File& file, T& value) {
+  file.read(reinterpret_cast<uint8_t*>(&value), sizeof(T));
+}
+
 static void writeString(std::ostream& os, const std::string& s) {
   const uint32_t len = s.size();
   writePod(os, len);
   os.write(s.data(), len);
 }
 
+static void writeString(File& file, const std::string& s) {
+  const uint32_t len = s.size();
+  writePod(file, len);
+  file.write(reinterpret_cast<const uint8_t*>(s.data()), len);
+}
+
 static void readString(std::istream& is, std::string& s) {
   uint32_t len;
   readPod(is, len);
   s.resize(len);
   is.read(&s[0], len);
 }
+
+static void readString(File& file, std::string& s) {
+  uint32_t len;
+  readPod(file, len);
+  s.resize(len);
+  file.read(reinterpret_cast<uint8_t*>(&s[0]), len);
+}
 }  // namespace serialization

platformio.ini

@@ -1,15 +1,15 @@
 [platformio]
-crosspoint_version = 0.8.0
+crosspoint_version = 0.9.0
 default_envs = default
 
 [base]
-platform = espressif32
+platform = espressif32 @ 6.12.0
 board = esp32-c3-devkitm-1
 framework = arduino
 monitor_speed = 115200
 upload_speed = 921600
 check_tool = cppcheck
-check_flags = --enable=all --suppress=missingIncludeSystem --suppress=unusedFunction --suppress=unmatchedSuppression --inline-suppr
+check_flags = --enable=all --suppress=missingIncludeSystem --suppress=unusedFunction --suppress=unmatchedSuppression --suppress=*:*/.pio/* --inline-suppr
 check_skip_packages = yes
 
 board_upload.flash_size = 16MB
@@ -39,6 +39,7 @@ lib_deps =
   BatteryMonitor=symlink://open-x4-sdk/libs/hardware/BatteryMonitor
   InputManager=symlink://open-x4-sdk/libs/hardware/InputManager
   EInkDisplay=symlink://open-x4-sdk/libs/display/EInkDisplay
+  ArduinoJson @ 7.4.2
 
 [env:default]
 extends = base

src/CrossPointSettings.cpp

@@ -1,26 +1,28 @@
 #include "CrossPointSettings.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
 #include <SD.h>
 #include <Serialization.h>
 
-#include <cstdint>
-#include <fstream>
-
 // Initialize the static instance
 CrossPointSettings CrossPointSettings::instance;
 
 namespace {
 constexpr uint8_t SETTINGS_FILE_VERSION = 1;
 constexpr uint8_t SETTINGS_COUNT = 3;
-constexpr char SETTINGS_FILE[] = "/sd/.crosspoint/settings.bin";
+constexpr char SETTINGS_FILE[] = "/.crosspoint/settings.bin";
 }  // namespace
 
 bool CrossPointSettings::saveToFile() const {
   // Make sure the directory exists
   SD.mkdir("/.crosspoint");
 
-  std::ofstream outputFile(SETTINGS_FILE);
+  File outputFile;
+  if (!FsHelpers::openFileForWrite("CPS", SETTINGS_FILE, outputFile)) {
+    return false;
+  }
+
   serialization::writePod(outputFile, SETTINGS_FILE_VERSION);
   serialization::writePod(outputFile, SETTINGS_COUNT);
   serialization::writePod(outputFile, sleepScreen);
@@ -33,13 +35,11 @@ bool CrossPointSettings::saveToFile() const {
 }
 
 bool CrossPointSettings::loadFromFile() {
-  if (!SD.exists(SETTINGS_FILE + 3)) {  // +3 to skip "/sd" prefix
-    Serial.printf("[%lu] [CPS] Settings file does not exist, using defaults\n", millis());
+  File inputFile;
+  if (!FsHelpers::openFileForRead("CPS", SETTINGS_FILE, inputFile)) {
     return false;
   }
 
-  std::ifstream inputFile(SETTINGS_FILE);
-
   uint8_t version;
   serialization::readPod(inputFile, version);
   if (version != SETTINGS_FILE_VERSION) {

src/CrossPointState.cpp

@@ -1,20 +1,22 @@
 #include "CrossPointState.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
-#include <SD.h>
 #include <Serialization.h>
 
-#include <fstream>
-
 namespace {
 constexpr uint8_t STATE_FILE_VERSION = 1;
-constexpr char STATE_FILE[] = "/sd/.crosspoint/state.bin";
+constexpr char STATE_FILE[] = "/.crosspoint/state.bin";
 }  // namespace
 
 CrossPointState CrossPointState::instance;
 
 bool CrossPointState::saveToFile() const {
-  std::ofstream outputFile(STATE_FILE);
+  File outputFile;
+  if (!FsHelpers::openFileForWrite("CPS", STATE_FILE, outputFile)) {
+    return false;
+  }
+
   serialization::writePod(outputFile, STATE_FILE_VERSION);
   serialization::writeString(outputFile, openEpubPath);
   outputFile.close();
@@ -22,7 +24,10 @@ bool CrossPointState::saveToFile() const {
 }
 
 bool CrossPointState::loadFromFile() {
-  std::ifstream inputFile(STATE_FILE);
+  File inputFile;
+  if (!FsHelpers::openFileForRead("CPS", STATE_FILE, inputFile)) {
+    return false;
+  }
 
   uint8_t version;
   serialization::readPod(inputFile, version);

src/WifiCredentialStore.cpp

@@ -1,11 +1,10 @@
 #include "WifiCredentialStore.h"
 
+#include <FsHelpers.h>
 #include <HardwareSerial.h>
 #include <SD.h>
 #include <Serialization.h>
 
-#include <fstream>
-
 // Initialize the static instance
 WifiCredentialStore WifiCredentialStore::instance;
 
@@ -14,7 +13,7 @@ namespace {
 constexpr uint8_t WIFI_FILE_VERSION = 1;
 
 // WiFi credentials file path
-constexpr char WIFI_FILE[] = "/sd/.crosspoint/wifi.bin";
+constexpr char WIFI_FILE[] = "/.crosspoint/wifi.bin";
 
 // Obfuscation key - "CrossPoint" in ASCII
 // This is NOT cryptographic security, just prevents casual file reading
@@ -33,9 +32,8 @@ bool WifiCredentialStore::saveToFile() const {
   // Make sure the directory exists
   SD.mkdir("/.crosspoint");
 
-  std::ofstream file(WIFI_FILE, std::ios::binary);
-  if (!file) {
-    Serial.printf("[%lu] [WCS] Failed to open wifi.bin for writing\n", millis());
+  File file;
+  if (!FsHelpers::openFileForWrite("WCS", WIFI_FILE, file)) {
     return false;
   }
 
@@ -62,14 +60,8 @@ bool WifiCredentialStore::saveToFile() const {
 }
 
 bool WifiCredentialStore::loadFromFile() {
-  if (!SD.exists(WIFI_FILE + 3)) {  // +3 to skip "/sd" prefix
-    Serial.printf("[%lu] [WCS] WiFi credentials file does not exist\n", millis());
-    return false;
-  }
-
-  std::ifstream file(WIFI_FILE, std::ios::binary);
-  if (!file) {
-    Serial.printf("[%lu] [WCS] Failed to open wifi.bin for reading\n", millis());
+  File file;
+  if (!FsHelpers::openFileForRead("WCS", WIFI_FILE, file)) {
     return false;
   }
 

src/activities/Activity.h

@@ -1,19 +1,25 @@
 #pragma once
-#include <InputManager.h>
 
+#include <HardwareSerial.h>
+
+#include <string>
+#include <utility>
+
+class InputManager;
 class GfxRenderer;
 
 class Activity {
  protected:
+  std::string name;
   GfxRenderer& renderer;
   InputManager& inputManager;
 
  public:
-  explicit Activity(GfxRenderer& renderer, InputManager& inputManager)
-      : renderer(renderer), inputManager(inputManager) {}
+  explicit Activity(std::string name, GfxRenderer& renderer, InputManager& inputManager)
+      : name(std::move(name)), renderer(renderer), inputManager(inputManager) {}
   virtual ~Activity() = default;
-  virtual void onEnter() {}
-  virtual void onExit() {}
+  virtual void onEnter() { Serial.printf("[%lu] [ACT] Entering activity: %s\n", millis(), name.c_str()); }
+  virtual void onExit() { Serial.printf("[%lu] [ACT] Exiting activity: %s\n", millis(), name.c_str()); }
   virtual void loop() {}
   virtual bool skipLoopDelay() { return false; }
 };

src/activities/ActivityWithSubactivity.cpp

@@ -18,4 +18,7 @@ void ActivityWithSubactivity::loop() {
   }
 }
 
-void ActivityWithSubactivity::onExit() { exitActivity(); }
+void ActivityWithSubactivity::onExit() {
+  Activity::onExit();
+  exitActivity();
+}

src/activities/ActivityWithSubactivity.h

@@ -10,8 +10,8 @@ class ActivityWithSubactivity : public Activity {
   void enterNewActivity(Activity* activity);
 
  public:
-  explicit ActivityWithSubactivity(GfxRenderer& renderer, InputManager& inputManager)
-      : Activity(renderer, inputManager) {}
+  explicit ActivityWithSubactivity(std::string name, GfxRenderer& renderer, InputManager& inputManager)
+      : Activity(std::move(name), renderer, inputManager) {}
   void loop() override;
   void onExit() override;
 };

src/activities/boot_sleep/BootActivity.cpp

@@ -6,6 +6,8 @@
 #include "images/CrossLarge.h"
 
 void BootActivity::onEnter() {
+  Activity::onEnter();
+
   const auto pageWidth = GfxRenderer::getScreenWidth();
   const auto pageHeight = GfxRenderer::getScreenHeight();
 

src/activities/boot_sleep/BootActivity.h

@@ -3,6 +3,6 @@
 
 class BootActivity final : public Activity {
  public:
-  explicit BootActivity(GfxRenderer& renderer, InputManager& inputManager) : Activity(renderer, inputManager) {}
+  explicit BootActivity(GfxRenderer& renderer, InputManager& inputManager) : Activity("Boot", renderer, inputManager) {}
   void onEnter() override;
 };

src/activities/boot_sleep/SleepActivity.cpp

@@ -1,6 +1,7 @@
 #include "SleepActivity.h"
 
 #include <Epub.h>
+#include <FsHelpers.h>
 #include <GfxRenderer.h>
 #include <SD.h>
 
@@ -12,6 +13,7 @@
 #include "images/CrossLarge.h"
 
 void SleepActivity::onEnter() {
+  Activity::onEnter();
   renderPopup("Entering Sleep...");
 
   if (SETTINGS.sleepScreen == CrossPointSettings::SLEEP_SCREEN_MODE::CUSTOM) {
@@ -75,8 +77,8 @@ void SleepActivity::renderCustomSleepScreen() const {
       // Generate a random number between 1 and numFiles
       const auto randomFileIndex = random(numFiles);
       const auto filename = "/sleep/" + files[randomFileIndex];
-      auto file = SD.open(filename.c_str());
-      if (file) {
+      File file;
+      if (FsHelpers::openFileForRead("SLP", filename, file)) {
         Serial.printf("[%lu] [SLP] Randomly loading: /sleep/%s\n", millis(), files[randomFileIndex].c_str());
         delay(100);
         Bitmap bitmap(file);
@@ -92,8 +94,8 @@ void SleepActivity::renderCustomSleepScreen() const {
 
   // Look for sleep.bmp on the root of the sd card to determine if we should
   // render a custom sleep screen instead of the default.
-  auto file = SD.open("/sleep.bmp");
-  if (file) {
+  File file;
+  if (FsHelpers::openFileForRead("SLP", "/sleep.bmp", file)) {
     Bitmap bitmap(file);
     if (bitmap.parseHeaders() == BmpReaderError::Ok) {
       Serial.printf("[%lu] [SLP] Loading: /sleep.bmp\n", millis());
@@ -170,18 +172,23 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap) const {
 }
 
 void SleepActivity::renderCoverSleepScreen() const {
+  if (APP_STATE.openEpubPath.empty()) {
+    return renderDefaultSleepScreen();
+  }
+
   Epub lastEpub(APP_STATE.openEpubPath, "/.crosspoint");
   if (!lastEpub.load()) {
     Serial.println("[SLP] Failed to load last epub");
     return renderDefaultSleepScreen();
   }
+
   if (!lastEpub.generateCoverBmp()) {
     Serial.println("[SLP] Failed to generate cover bmp");
     return renderDefaultSleepScreen();
   }
 
-  auto file = SD.open(lastEpub.getCoverBmpPath().c_str(), FILE_READ);
-  if (file) {
+  File file;
+  if (FsHelpers::openFileForRead("SLP", lastEpub.getCoverBmpPath(), file)) {
     Bitmap bitmap(file);
     if (bitmap.parseHeaders() == BmpReaderError::Ok) {
       renderBitmapSleepScreen(bitmap);

src/activities/boot_sleep/SleepActivity.h

@@ -5,7 +5,8 @@ class Bitmap;
 
 class SleepActivity final : public Activity {
  public:
-  explicit SleepActivity(GfxRenderer& renderer, InputManager& inputManager) : Activity(renderer, inputManager) {}
+  explicit SleepActivity(GfxRenderer& renderer, InputManager& inputManager)
+      : Activity("Sleep", renderer, inputManager) {}
   void onEnter() override;
 
  private:

src/activities/home/HomeActivity.cpp

@@ -1,6 +1,7 @@
 #include "HomeActivity.h"
 
 #include <GfxRenderer.h>
+#include <InputManager.h>
 #include <SD.h>
 
 #include "config.h"
@@ -15,6 +16,8 @@ void HomeActivity::taskTrampoline(void* param) {
 }
 
 void HomeActivity::onEnter() {
+  Activity::onEnter();
+
   renderingMutex = xSemaphoreCreateMutex();
 
   selectorIndex = 0;
@@ -31,6 +34,8 @@ void HomeActivity::onEnter() {
 }
 
 void HomeActivity::onExit() {
+  Activity::onExit();
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {
@@ -79,8 +84,8 @@ void HomeActivity::displayTaskLoop() {
 void HomeActivity::render() const {
   renderer.clearScreen();
 
-  const auto pageWidth = GfxRenderer::getScreenWidth();
-  const auto pageHeight = GfxRenderer::getScreenHeight();
+  const auto pageWidth = renderer.getScreenWidth();
+  const auto pageHeight = renderer.getScreenHeight();
   renderer.drawCenteredText(READER_FONT_ID, 10, "CrossPoint Reader", true, BOLD);
 
   // Draw selection

src/activities/home/HomeActivity.h

@@ -23,7 +23,7 @@ class HomeActivity final : public Activity {
  public:
   explicit HomeActivity(GfxRenderer& renderer, InputManager& inputManager, const std::function<void()>& onReaderOpen,
                         const std::function<void()>& onSettingsOpen, const std::function<void()>& onFileTransferOpen)
-      : Activity(renderer, inputManager),
+      : Activity("Home", renderer, inputManager),
         onReaderOpen(onReaderOpen),
         onSettingsOpen(onSettingsOpen),
         onFileTransferOpen(onFileTransferOpen) {}

src/activities/network/CrossPointWebServerActivity.cpp

@@ -1,23 +1,44 @@
 #include "CrossPointWebServerActivity.h"
 
+#include <DNSServer.h>
+#include <ESPmDNS.h>
 #include <GfxRenderer.h>
+#include <InputManager.h>
 #include <WiFi.h>
 
+#include "NetworkModeSelectionActivity.h"
+#include "WifiSelectionActivity.h"
 #include "config.h"
 
+namespace {
+// AP Mode configuration
+constexpr const char* AP_SSID = "CrossPoint-Reader";
+constexpr const char* AP_PASSWORD = nullptr;  // Open network for ease of use
+constexpr const char* AP_HOSTNAME = "crosspoint";
+constexpr uint8_t AP_CHANNEL = 1;
+constexpr uint8_t AP_MAX_CONNECTIONS = 4;
+
+// DNS server for captive portal (redirects all DNS queries to our IP)
+DNSServer* dnsServer = nullptr;
+constexpr uint16_t DNS_PORT = 53;
+}  // namespace
+
 void CrossPointWebServerActivity::taskTrampoline(void* param) {
   auto* self = static_cast<CrossPointWebServerActivity*>(param);
   self->displayTaskLoop();
 }
 
 void CrossPointWebServerActivity::onEnter() {
-  Serial.printf("[%lu] [WEBACT] ========== CrossPointWebServerActivity onEnter ==========\n", millis());
+  ActivityWithSubactivity::onEnter();
+
   Serial.printf("[%lu] [WEBACT] [MEM] Free heap at onEnter: %d bytes\n", millis(), ESP.getFreeHeap());
 
   renderingMutex = xSemaphoreCreateMutex();
 
   // Reset state
-  state = WebServerActivityState::WIFI_SELECTION;
+  state = WebServerActivityState::MODE_SELECTION;
+  networkMode = NetworkMode::JOIN_NETWORK;
+  isApMode = false;
   connectedIP.clear();
   connectedSSID.clear();
   lastHandleClientTime = 0;
@@ -30,19 +51,17 @@ void CrossPointWebServerActivity::onEnter() {
               &displayTaskHandle  // Task handle
   );
 
-  // Turn on WiFi immediately
-  Serial.printf("[%lu] [WEBACT] Turning on WiFi...\n", millis());
-  WiFi.mode(WIFI_STA);
-
-  // Launch WiFi selection subactivity
-  Serial.printf("[%lu] [WEBACT] Launching WifiSelectionActivity...\n", millis());
-  wifiSelection.reset(new WifiSelectionActivity(renderer, inputManager,
-                                                [this](bool connected) { onWifiSelectionComplete(connected); }));
-  wifiSelection->onEnter();
+  // Launch network mode selection subactivity
+  Serial.printf("[%lu] [WEBACT] Launching NetworkModeSelectionActivity...\n", millis());
+  enterNewActivity(new NetworkModeSelectionActivity(
+      renderer, inputManager, [this](const NetworkMode mode) { onNetworkModeSelected(mode); },
+      [this]() { onGoBack(); }  // Cancel goes back to home
+      ));
 }
 
 void CrossPointWebServerActivity::onExit() {
-  Serial.printf("[%lu] [WEBACT] ========== CrossPointWebServerActivity onExit START ==========\n", millis());
+  ActivityWithSubactivity::onExit();
+
   Serial.printf("[%lu] [WEBACT] [MEM] Free heap at onExit start: %d bytes\n", millis(), ESP.getFreeHeap());
 
   state = WebServerActivityState::SHUTTING_DOWN;
@@ -50,12 +69,15 @@ void CrossPointWebServerActivity::onExit() {
   // Stop the web server first (before disconnecting WiFi)
   stopWebServer();
 
-  // Exit WiFi selection subactivity if still active
-  if (wifiSelection) {
-    Serial.printf("[%lu] [WEBACT] Exiting WifiSelectionActivity...\n", millis());
-    wifiSelection->onExit();
-    wifiSelection.reset();
-    Serial.printf("[%lu] [WEBACT] WifiSelectionActivity exited\n", millis());
+  // Stop mDNS
+  MDNS.end();
+
+  // Stop DNS server if running (AP mode)
+  if (dnsServer) {
+    Serial.printf("[%lu] [WEBACT] Stopping DNS server...\n", millis());
+    dnsServer->stop();
+    delete dnsServer;
+    dnsServer = nullptr;
   }
 
   // CRITICAL: Wait for LWIP stack to flush any pending packets
@@ -63,8 +85,13 @@ void CrossPointWebServerActivity::onExit() {
   delay(500);
 
   // Disconnect WiFi gracefully
+  if (isApMode) {
+    Serial.printf("[%lu] [WEBACT] Stopping WiFi AP...\n", millis());
+    WiFi.softAPdisconnect(true);
+  } else {
     Serial.printf("[%lu] [WEBACT] Disconnecting WiFi (graceful)...\n", millis());
     WiFi.disconnect(false);  // false = don't erase credentials, send disconnect frame
+  }
   delay(100);  // Allow disconnect frame to be sent
 
   Serial.printf("[%lu] [WEBACT] Setting WiFi mode OFF...\n", millis());
@@ -92,29 +119,119 @@ void CrossPointWebServerActivity::onExit() {
   Serial.printf("[%lu] [WEBACT] Mutex deleted\n", millis());
 
   Serial.printf("[%lu] [WEBACT] [MEM] Free heap at onExit end: %d bytes\n", millis(), ESP.getFreeHeap());
-  Serial.printf("[%lu] [WEBACT] ========== CrossPointWebServerActivity onExit COMPLETE ==========\n", millis());
 }
 
-void CrossPointWebServerActivity::onWifiSelectionComplete(bool connected) {
+void CrossPointWebServerActivity::onNetworkModeSelected(const NetworkMode mode) {
+  Serial.printf("[%lu] [WEBACT] Network mode selected: %s\n", millis(),
+                mode == NetworkMode::JOIN_NETWORK ? "Join Network" : "Create Hotspot");
+
+  networkMode = mode;
+  isApMode = (mode == NetworkMode::CREATE_HOTSPOT);
+
+  // Exit mode selection subactivity
+  exitActivity();
+
+  if (mode == NetworkMode::JOIN_NETWORK) {
+    // STA mode - launch WiFi selection
+    Serial.printf("[%lu] [WEBACT] Turning on WiFi (STA mode)...\n", millis());
+    WiFi.mode(WIFI_STA);
+
+    state = WebServerActivityState::WIFI_SELECTION;
+    Serial.printf("[%lu] [WEBACT] Launching WifiSelectionActivity...\n", millis());
+    enterNewActivity(new WifiSelectionActivity(renderer, inputManager,
+                                               [this](const bool connected) { onWifiSelectionComplete(connected); }));
+  } else {
+    // AP mode - start access point
+    state = WebServerActivityState::AP_STARTING;
+    updateRequired = true;
+    startAccessPoint();
+  }
+}
+
+void CrossPointWebServerActivity::onWifiSelectionComplete(const bool connected) {
   Serial.printf("[%lu] [WEBACT] WifiSelectionActivity completed, connected=%d\n", millis(), connected);
 
   if (connected) {
     // Get connection info before exiting subactivity
-    connectedIP = wifiSelection->getConnectedIP();
+    connectedIP = static_cast<WifiSelectionActivity*>(subActivity.get())->getConnectedIP();
     connectedSSID = WiFi.SSID().c_str();
+    isApMode = false;
 
-    // Exit the wifi selection subactivity
-    wifiSelection->onExit();
-    wifiSelection.reset();
+    exitActivity();
+
+    // Start mDNS for hostname resolution
+    if (MDNS.begin(AP_HOSTNAME)) {
+      Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), AP_HOSTNAME);
+    }
 
     // Start the web server
     startWebServer();
   } else {
-    // User cancelled - go back
-    onGoBack();
+    // User cancelled - go back to mode selection
+    exitActivity();
+    state = WebServerActivityState::MODE_SELECTION;
+    enterNewActivity(new NetworkModeSelectionActivity(
+        renderer, inputManager, [this](const NetworkMode mode) { onNetworkModeSelected(mode); },
+        [this]() { onGoBack(); }));
   }
 }
 
+void CrossPointWebServerActivity::startAccessPoint() {
+  Serial.printf("[%lu] [WEBACT] Starting Access Point mode...\n", millis());
+  Serial.printf("[%lu] [WEBACT] [MEM] Free heap before AP start: %d bytes\n", millis(), ESP.getFreeHeap());
+
+  // Configure and start the AP
+  WiFi.mode(WIFI_AP);
+  delay(100);
+
+  // Start soft AP
+  bool apStarted;
+  if (AP_PASSWORD && strlen(AP_PASSWORD) >= 8) {
+    apStarted = WiFi.softAP(AP_SSID, AP_PASSWORD, AP_CHANNEL, false, AP_MAX_CONNECTIONS);
+  } else {
+    // Open network (no password)
+    apStarted = WiFi.softAP(AP_SSID, nullptr, AP_CHANNEL, false, AP_MAX_CONNECTIONS);
+  }
+
+  if (!apStarted) {
+    Serial.printf("[%lu] [WEBACT] ERROR: Failed to start Access Point!\n", millis());
+    onGoBack();
+    return;
+  }
+
+  delay(100);  // Wait for AP to fully initialize
+
+  // Get AP IP address
+  const IPAddress apIP = WiFi.softAPIP();
+  char ipStr[16];
+  snprintf(ipStr, sizeof(ipStr), "%d.%d.%d.%d", apIP[0], apIP[1], apIP[2], apIP[3]);
+  connectedIP = ipStr;
+  connectedSSID = AP_SSID;
+
+  Serial.printf("[%lu] [WEBACT] Access Point started!\n", millis());
+  Serial.printf("[%lu] [WEBACT] SSID: %s\n", millis(), AP_SSID);
+  Serial.printf("[%lu] [WEBACT] IP: %s\n", millis(), connectedIP.c_str());
+
+  // Start mDNS for hostname resolution
+  if (MDNS.begin(AP_HOSTNAME)) {
+    Serial.printf("[%lu] [WEBACT] mDNS started: http://%s.local/\n", millis(), AP_HOSTNAME);
+  } else {
+    Serial.printf("[%lu] [WEBACT] WARNING: mDNS failed to start\n", millis());
+  }
+
+  // Start DNS server for captive portal behavior
+  // This redirects all DNS queries to our IP, making any domain typed resolve to us
+  dnsServer = new DNSServer();
+  dnsServer->setErrorReplyCode(DNSReplyCode::NoError);
+  dnsServer->start(DNS_PORT, "*", apIP);
+  Serial.printf("[%lu] [WEBACT] DNS server started for captive portal\n", millis());
+
+  Serial.printf("[%lu] [WEBACT] [MEM] Free heap after AP start: %d bytes\n", millis(), ESP.getFreeHeap());
+
+  // Start the web server
+  startWebServer();
+}
+
 void CrossPointWebServerActivity::startWebServer() {
   Serial.printf("[%lu] [WEBACT] Starting web server...\n", millis());
 
@@ -150,20 +267,23 @@ void CrossPointWebServerActivity::stopWebServer() {
 }
 
 void CrossPointWebServerActivity::loop() {
-  // Handle different states
-  switch (state) {
-    case WebServerActivityState::WIFI_SELECTION:
-      // Forward loop to WiFi selection subactivity
-      if (wifiSelection) {
-        wifiSelection->loop();
+  if (subActivity) {
+    // Forward loop to subactivity
+    subActivity->loop();
+    return;
+  }
+
+  // Handle different states
+  if (state == WebServerActivityState::SERVER_RUNNING) {
+    // Handle DNS requests for captive portal (AP mode only)
+    if (isApMode && dnsServer) {
+      dnsServer->processNextRequest();
     }
-      break;
 
-    case WebServerActivityState::SERVER_RUNNING:
     // Handle web server requests - call handleClient multiple times per loop
     // to improve responsiveness and upload throughput
     if (webServer && webServer->isRunning()) {
-        unsigned long timeSinceLastHandleClient = millis() - lastHandleClientTime;
+      const unsigned long timeSinceLastHandleClient = millis() - lastHandleClientTime;
 
       // Log if there's a significant gap between handleClient calls (>100ms)
       if (lastHandleClientTime > 0 && timeSinceLastHandleClient > 100) {
@@ -186,11 +306,6 @@ void CrossPointWebServerActivity::loop() {
       onGoBack();
       return;
     }
-      break;
-
-    case WebServerActivityState::SHUTTING_DOWN:
-      // Do nothing - waiting for cleanup
-      break;
   }
 }
 
@@ -208,35 +323,71 @@ void CrossPointWebServerActivity::displayTaskLoop() {
 
 void CrossPointWebServerActivity::render() const {
   // Only render our own UI when server is running
-  // WiFi selection handles its own rendering
+  // Subactivities handle their own rendering
   if (state == WebServerActivityState::SERVER_RUNNING) {
     renderer.clearScreen();
     renderServerRunning();
     renderer.displayBuffer();
+  } else if (state == WebServerActivityState::AP_STARTING) {
+    renderer.clearScreen();
+    const auto pageHeight = renderer.getScreenHeight();
+    renderer.drawCenteredText(READER_FONT_ID, pageHeight / 2 - 20, "Starting Hotspot...", true, BOLD);
+    renderer.displayBuffer();
   }
 }
 
 void CrossPointWebServerActivity::renderServerRunning() const {
   const auto pageHeight = renderer.getScreenHeight();
-  const auto height = renderer.getLineHeight(UI_FONT_ID);
-  const auto top = (pageHeight - height * 5) / 2;
 
-  renderer.drawCenteredText(READER_FONT_ID, top - 30, "File Transfer", true, BOLD);
+  // Use consistent line spacing
+  constexpr int LINE_SPACING = 28;  // Space between lines
+
+  renderer.drawCenteredText(READER_FONT_ID, 15, "File Transfer", true, BOLD);
+
+  if (isApMode) {
+    // AP mode display - center the content block
+    const int startY = 55;
+
+    renderer.drawCenteredText(UI_FONT_ID, startY, "Hotspot Mode", true, BOLD);
+
+    std::string ssidInfo = "Network: " + connectedSSID;
+    renderer.drawCenteredText(UI_FONT_ID, startY + LINE_SPACING, ssidInfo.c_str(), true, REGULAR);
+
+    renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 2, "Connect your device to this WiFi network",
+                              true, REGULAR);
+
+    // Show primary URL (hostname)
+    std::string hostnameUrl = std::string("http://") + AP_HOSTNAME + ".local/";
+    renderer.drawCenteredText(UI_FONT_ID, startY + LINE_SPACING * 3, hostnameUrl.c_str(), true, BOLD);
+
+    // Show IP address as fallback
+    std::string ipUrl = "or http://" + connectedIP + "/";
+    renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 4, ipUrl.c_str(), true, REGULAR);
+
+    renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 5, "Open this URL in your browser", true, REGULAR);
+  } else {
+    // STA mode display (original behavior)
+    const int startY = 65;
 
     std::string ssidInfo = "Network: " + connectedSSID;
     if (ssidInfo.length() > 28) {
       ssidInfo.replace(25, ssidInfo.length() - 25, "...");
     }
-  renderer.drawCenteredText(UI_FONT_ID, top + 10, ssidInfo.c_str(), true, REGULAR);
+    renderer.drawCenteredText(UI_FONT_ID, startY, ssidInfo.c_str(), true, REGULAR);
 
     std::string ipInfo = "IP Address: " + connectedIP;
-  renderer.drawCenteredText(UI_FONT_ID, top + 40, ipInfo.c_str(), true, REGULAR);
+    renderer.drawCenteredText(UI_FONT_ID, startY + LINE_SPACING, ipInfo.c_str(), true, REGULAR);
 
     // Show web server URL prominently
     std::string webInfo = "http://" + connectedIP + "/";
-  renderer.drawCenteredText(UI_FONT_ID, top + 70, webInfo.c_str(), true, BOLD);
+    renderer.drawCenteredText(UI_FONT_ID, startY + LINE_SPACING * 2, webInfo.c_str(), true, BOLD);
 
-  renderer.drawCenteredText(SMALL_FONT_ID, top + 110, "Open this URL in your browser", true, REGULAR);
+    // Also show hostname URL
+    std::string hostnameUrl = std::string("or http://") + AP_HOSTNAME + ".local/";
+    renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 3, hostnameUrl.c_str(), true, REGULAR);
+
+    renderer.drawCenteredText(SMALL_FONT_ID, startY + LINE_SPACING * 4, "Open this URL in your browser", true, REGULAR);
+  }
 
   renderer.drawCenteredText(SMALL_FONT_ID, pageHeight - 30, "Press BACK to exit", true, REGULAR);
 }

src/activities/network/CrossPointWebServerActivity.h

@@ -7,13 +7,15 @@
 #include <memory>
 #include <string>
 
-#include "../Activity.h"
-#include "WifiSelectionActivity.h"
-#include "server/CrossPointWebServer.h"
+#include "NetworkModeSelectionActivity.h"
+#include "activities/ActivityWithSubactivity.h"
+#include "network/CrossPointWebServer.h"
 
 // Web server activity states
 enum class WebServerActivityState {
-  WIFI_SELECTION,  // WiFi selection subactivity is active
+  MODE_SELECTION,  // Choosing between Join Network and Create Hotspot
+  WIFI_SELECTION,  // WiFi selection subactivity is active (for Join Network mode)
+  AP_STARTING,     // Starting Access Point mode
   SERVER_RUNNING,  // Web server is running and handling requests
   SHUTTING_DOWN    // Shutting down server and WiFi
 };
@@ -21,27 +23,30 @@ enum class WebServerActivityState {
 /**
  * CrossPointWebServerActivity is the entry point for file transfer functionality.
  * It:
- * - Immediately turns on WiFi and launches WifiSelectionActivity on enter
- * - When WifiSelectionActivity completes successfully, starts the CrossPointWebServer
+ * - First presents a choice between "Join a Network" (STA) and "Create Hotspot" (AP)
+ * - For STA mode: Launches WifiSelectionActivity to connect to an existing network
+ * - For AP mode: Creates an Access Point that clients can connect to
+ * - Starts the CrossPointWebServer when connected
  * - Handles client requests in its loop() function
  * - Cleans up the server and shuts down WiFi on exit
  */
-class CrossPointWebServerActivity final : public Activity {
+class CrossPointWebServerActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
   bool updateRequired = false;
-  WebServerActivityState state = WebServerActivityState::WIFI_SELECTION;
+  WebServerActivityState state = WebServerActivityState::MODE_SELECTION;
   const std::function<void()> onGoBack;
 
-  // WiFi selection subactivity
-  std::unique_ptr<WifiSelectionActivity> wifiSelection;
+  // Network mode
+  NetworkMode networkMode = NetworkMode::JOIN_NETWORK;
+  bool isApMode = false;
 
   // Web server - owned by this activity
   std::unique_ptr<CrossPointWebServer> webServer;
 
   // Server status
   std::string connectedIP;
-  std::string connectedSSID;
+  std::string connectedSSID;  // For STA mode: network name, For AP mode: AP name
 
   // Performance monitoring
   unsigned long lastHandleClientTime = 0;
@@ -51,14 +56,16 @@ class CrossPointWebServerActivity final : public Activity {
   void render() const;
   void renderServerRunning() const;
 
+  void onNetworkModeSelected(NetworkMode mode);
   void onWifiSelectionComplete(bool connected);
+  void startAccessPoint();
   void startWebServer();
   void stopWebServer();
 
  public:
   explicit CrossPointWebServerActivity(GfxRenderer& renderer, InputManager& inputManager,
                                        const std::function<void()>& onGoBack)
-      : Activity(renderer, inputManager), onGoBack(onGoBack) {}
+      : ActivityWithSubactivity("CrossPointWebServer", renderer, inputManager), onGoBack(onGoBack) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/network/NetworkModeSelectionActivity.cpp

@@ -0,0 +1,128 @@
+#include "NetworkModeSelectionActivity.h"
+
+#include <GfxRenderer.h>
+#include <InputManager.h>
+
+#include "config.h"
+
+namespace {
+constexpr int MENU_ITEM_COUNT = 2;
+const char* MENU_ITEMS[MENU_ITEM_COUNT] = {"Join a Network", "Create Hotspot"};
+const char* MENU_DESCRIPTIONS[MENU_ITEM_COUNT] = {"Connect to an existing WiFi network",
+                                                  "Create a WiFi network others can join"};
+}  // namespace
+
+void NetworkModeSelectionActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<NetworkModeSelectionActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void NetworkModeSelectionActivity::onEnter() {
+  Activity::onEnter();
+
+  renderingMutex = xSemaphoreCreateMutex();
+
+  // Reset selection
+  selectedIndex = 0;
+
+  // Trigger first update
+  updateRequired = true;
+
+  xTaskCreate(&NetworkModeSelectionActivity::taskTrampoline, "NetworkModeTask",
+              2048,               // Stack size
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+}
+
+void NetworkModeSelectionActivity::onExit() {
+  Activity::onExit();
+
+  // Wait until not rendering to delete task
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+void NetworkModeSelectionActivity::loop() {
+  // Handle back button - cancel
+  if (inputManager.wasPressed(InputManager::BTN_BACK)) {
+    onCancel();
+    return;
+  }
+
+  // Handle confirm button - select current option
+  if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
+    const NetworkMode mode = (selectedIndex == 0) ? NetworkMode::JOIN_NETWORK : NetworkMode::CREATE_HOTSPOT;
+    onModeSelected(mode);
+    return;
+  }
+
+  // Handle navigation
+  const bool prevPressed =
+      inputManager.wasPressed(InputManager::BTN_UP) || inputManager.wasPressed(InputManager::BTN_LEFT);
+  const bool nextPressed =
+      inputManager.wasPressed(InputManager::BTN_DOWN) || inputManager.wasPressed(InputManager::BTN_RIGHT);
+
+  if (prevPressed) {
+    selectedIndex = (selectedIndex + MENU_ITEM_COUNT - 1) % MENU_ITEM_COUNT;
+    updateRequired = true;
+  } else if (nextPressed) {
+    selectedIndex = (selectedIndex + 1) % MENU_ITEM_COUNT;
+    updateRequired = true;
+  }
+}
+
+void NetworkModeSelectionActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void NetworkModeSelectionActivity::render() const {
+  renderer.clearScreen();
+
+  const auto pageWidth = renderer.getScreenWidth();
+  const auto pageHeight = renderer.getScreenHeight();
+
+  // Draw header
+  renderer.drawCenteredText(READER_FONT_ID, 10, "File Transfer", true, BOLD);
+
+  // Draw subtitle
+  renderer.drawCenteredText(UI_FONT_ID, 50, "How would you like to connect?", true, REGULAR);
+
+  // Draw menu items centered on screen
+  constexpr int itemHeight = 50;  // Height for each menu item (including description)
+  const int startY = (pageHeight - (MENU_ITEM_COUNT * itemHeight)) / 2 + 10;
+
+  for (int i = 0; i < MENU_ITEM_COUNT; i++) {
+    const int itemY = startY + i * itemHeight;
+    const bool isSelected = (i == selectedIndex);
+
+    // Draw selection highlight (black fill) for selected item
+    if (isSelected) {
+      renderer.fillRect(20, itemY - 2, pageWidth - 40, itemHeight - 6);
+    }
+
+    // Draw text: black=false (white text) when selected (on black background)
+    //            black=true (black text) when not selected (on white background)
+    renderer.drawText(UI_FONT_ID, 30, itemY, MENU_ITEMS[i], /*black=*/!isSelected);
+    renderer.drawText(SMALL_FONT_ID, 30, itemY + 22, MENU_DESCRIPTIONS[i], /*black=*/!isSelected);
+  }
+
+  // Draw help text at bottom
+  renderer.drawCenteredText(SMALL_FONT_ID, pageHeight - 30, "Press OK to select, BACK to cancel", true, REGULAR);
+
+  renderer.displayBuffer();
+}

src/activities/network/NetworkModeSelectionActivity.h

@@ -0,0 +1,41 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+
+#include "../Activity.h"
+
+// Enum for network mode selection
+enum class NetworkMode { JOIN_NETWORK, CREATE_HOTSPOT };
+
+/**
+ * NetworkModeSelectionActivity presents the user with a choice:
+ * - "Join a Network" - Connect to an existing WiFi network (STA mode)
+ * - "Create Hotspot" - Create an Access Point that others can connect to (AP mode)
+ *
+ * The onModeSelected callback is called with the user's choice.
+ * The onCancel callback is called if the user presses back.
+ */
+class NetworkModeSelectionActivity final : public Activity {
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  int selectedIndex = 0;
+  bool updateRequired = false;
+  const std::function<void(NetworkMode)> onModeSelected;
+  const std::function<void()> onCancel;
+
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render() const;
+
+ public:
+  explicit NetworkModeSelectionActivity(GfxRenderer& renderer, InputManager& inputManager,
+                                        const std::function<void(NetworkMode)>& onModeSelected,
+                                        const std::function<void()>& onCancel)
+      : Activity("NetworkModeSelection", renderer, inputManager), onModeSelected(onModeSelected), onCancel(onCancel) {}
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+};

src/activities/network/WifiSelectionActivity.cpp

@@ -6,6 +6,7 @@
 #include <map>
 
 #include "WifiCredentialStore.h"
+#include "activities/util/KeyboardEntryActivity.h"
 #include "config.h"
 
 void WifiSelectionActivity::taskTrampoline(void* param) {
@@ -14,10 +15,14 @@ void WifiSelectionActivity::taskTrampoline(void* param) {
 }
 
 void WifiSelectionActivity::onEnter() {
+  Activity::onEnter();
+
   renderingMutex = xSemaphoreCreateMutex();
 
-  // Load saved WiFi credentials
+  // Load saved WiFi credentials - SD card operations need lock as we use SPI for both
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
   WIFI_STORE.loadFromFile();
+  xSemaphoreGive(renderingMutex);
 
   // Reset state
   selectedNetworkIndex = 0;
@@ -30,7 +35,6 @@ void WifiSelectionActivity::onEnter() {
   usedSavedPassword = false;
   savePromptSelection = 0;
   forgetPromptSelection = 0;
-  keyboard.reset();
 
   // Trigger first update to show scanning message
   updateRequired = true;
@@ -47,7 +51,8 @@ void WifiSelectionActivity::onEnter() {
 }
 
 void WifiSelectionActivity::onExit() {
-  Serial.printf("[%lu] [WIFI] ========== WifiSelectionActivity onExit START ==========\n", millis());
+  Activity::onExit();
+
   Serial.printf("[%lu] [WIFI] [MEM] Free heap at onExit start: %d bytes\n", millis(), ESP.getFreeHeap());
 
   // Stop any ongoing WiFi scan
@@ -78,7 +83,6 @@ void WifiSelectionActivity::onExit() {
   Serial.printf("[%lu] [WIFI] Mutex deleted\n", millis());
 
   Serial.printf("[%lu] [WIFI] [MEM] Free heap at onExit end: %d bytes\n", millis(), ESP.getFreeHeap());
-  Serial.printf("[%lu] [WIFI] ========== WifiSelectionActivity onExit COMPLETE ==========\n", millis());
 }
 
 void WifiSelectionActivity::startWifiScan() {
@@ -96,7 +100,7 @@ void WifiSelectionActivity::startWifiScan() {
 }
 
 void WifiSelectionActivity::processWifiScanResults() {
-  int16_t scanResult = WiFi.scanComplete();
+  const int16_t scanResult = WiFi.scanComplete();
 
   if (scanResult == WIFI_SCAN_RUNNING) {
     // Scan still in progress
@@ -115,7 +119,7 @@ void WifiSelectionActivity::processWifiScanResults() {
 
   for (int i = 0; i < scanResult; i++) {
     std::string ssid = WiFi.SSID(i).c_str();
-    int32_t rssi = WiFi.RSSI(i);
+    const int32_t rssi = WiFi.RSSI(i);
 
     // Skip hidden networks (empty SSID)
     if (ssid.empty()) {
@@ -152,7 +156,7 @@ void WifiSelectionActivity::processWifiScanResults() {
   updateRequired = true;
 }
 
-void WifiSelectionActivity::selectNetwork(int index) {
+void WifiSelectionActivity::selectNetwork(const int index) {
   if (index < 0 || index >= static_cast<int>(networks.size())) {
     return;
   }
@@ -178,7 +182,7 @@ void WifiSelectionActivity::selectNetwork(int index) {
   if (selectedRequiresPassword) {
     // Show password entry
     state = WifiSelectionState::PASSWORD_ENTRY;
-    keyboard.reset(new KeyboardEntryActivity(renderer, inputManager, "Enter WiFi Password",
+    enterNewActivity(new KeyboardEntryActivity(renderer, inputManager, "Enter WiFi Password",
                                                "",    // No initial text
                                                64,    // Max password length
                                                false  // Show password by default (hard keyboard to use)
@@ -200,8 +204,8 @@ void WifiSelectionActivity::attemptConnection() {
   WiFi.mode(WIFI_STA);
 
   // Get password from keyboard if we just entered it
-  if (keyboard && !usedSavedPassword) {
-    enteredPassword = keyboard->getText();
+  if (subActivity && !usedSavedPassword) {
+    enteredPassword = static_cast<KeyboardEntryActivity*>(subActivity.get())->getText();
   }
 
   if (selectedRequiresPassword && !enteredPassword.empty()) {
@@ -216,7 +220,7 @@ void WifiSelectionActivity::checkConnectionStatus() {
     return;
   }
 
-  wl_status_t status = WiFi.status();
+  const wl_status_t status = WiFi.status();
 
   if (status == WL_CONNECTED) {
     // Successfully connected
@@ -273,7 +277,8 @@ void WifiSelectionActivity::loop() {
   }
 
   // Handle password entry state
-  if (state == WifiSelectionState::PASSWORD_ENTRY && keyboard) {
+  if (state == WifiSelectionState::PASSWORD_ENTRY && subActivity) {
+    const auto keyboard = static_cast<KeyboardEntryActivity*>(subActivity.get());
     keyboard->handleInput();
 
     if (keyboard->isComplete()) {
@@ -283,7 +288,7 @@ void WifiSelectionActivity::loop() {
 
     if (keyboard->isCancelled()) {
       state = WifiSelectionState::NETWORK_LIST;
-      keyboard.reset();
+      exitActivity();
       updateRequired = true;
       return;
     }
@@ -307,7 +312,9 @@ void WifiSelectionActivity::loop() {
     } else if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
       if (savePromptSelection == 0) {
         // User chose "Yes" - save the password
+        xSemaphoreTake(renderingMutex, portMAX_DELAY);
         WIFI_STORE.addCredential(selectedSSID, enteredPassword);
+        xSemaphoreGive(renderingMutex);
       }
       // Complete - parent will start web server
       onComplete(true);
@@ -333,7 +340,9 @@ void WifiSelectionActivity::loop() {
     } else if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
       if (forgetPromptSelection == 0) {
         // User chose "Yes" - forget the network
+        xSemaphoreTake(renderingMutex, portMAX_DELAY);
         WIFI_STORE.removeCredential(selectedSSID);
+        xSemaphoreGive(renderingMutex);
         // Update the network list to reflect the change
         const auto network = find_if(networks.begin(), networks.end(),
                                      [this](const WifiNetworkInfo& net) { return net.ssid == selectedSSID; });
@@ -408,15 +417,18 @@ void WifiSelectionActivity::loop() {
   }
 }
 
-std::string WifiSelectionActivity::getSignalStrengthIndicator(int32_t rssi) const {
+std::string WifiSelectionActivity::getSignalStrengthIndicator(const int32_t rssi) const {
   // Convert RSSI to signal bars representation
   if (rssi >= -50) {
     return "||||";  // Excellent
-  } else if (rssi >= -60) {
+  }
+  if (rssi >= -60) {
     return "||| ";  // Good
-  } else if (rssi >= -70) {
+  }
+  if (rssi >= -70) {
     return "||  ";  // Fair
-  } else if (rssi >= -80) {
+  }
+  if (rssi >= -80) {
     return "|   ";  // Weak
   }
   return "    ";  // Very weak
@@ -482,8 +494,8 @@ void WifiSelectionActivity::renderNetworkList() const {
     renderer.drawCenteredText(SMALL_FONT_ID, top + height + 10, "Press OK to scan again", true, REGULAR);
   } else {
     // Calculate how many networks we can display
-    const int startY = 60;
-    const int lineHeight = 25;
+    constexpr int startY = 60;
+    constexpr int lineHeight = 25;
     const int maxVisibleNetworks = (pageHeight - startY - 40) / lineHeight;
 
     // Calculate scroll offset to keep selected item visible
@@ -555,8 +567,8 @@ void WifiSelectionActivity::renderPasswordEntry() const {
   renderer.drawCenteredText(UI_FONT_ID, 38, networkInfo.c_str(), true, REGULAR);
 
   // Draw keyboard
-  if (keyboard) {
-    keyboard->render(58);
+  if (subActivity) {
+    static_cast<KeyboardEntryActivity*>(subActivity.get())->render(58);
   }
 }
 
@@ -591,7 +603,7 @@ void WifiSelectionActivity::renderConnected() const {
   }
   renderer.drawCenteredText(UI_FONT_ID, top + 10, ssidInfo.c_str(), true, REGULAR);
 
-  std::string ipInfo = "IP Address: " + connectedIP;
+  const std::string ipInfo = "IP Address: " + connectedIP;
   renderer.drawCenteredText(UI_FONT_ID, top + 40, ipInfo.c_str(), true, REGULAR);
 
   renderer.drawCenteredText(SMALL_FONT_ID, pageHeight - 30, "Press any button to continue", true, REGULAR);
@@ -615,9 +627,9 @@ void WifiSelectionActivity::renderSavePrompt() const {
 
   // Draw Yes/No buttons
   const int buttonY = top + 80;
-  const int buttonWidth = 60;
-  const int buttonSpacing = 30;
-  const int totalWidth = buttonWidth * 2 + buttonSpacing;
+  constexpr int buttonWidth = 60;
+  constexpr int buttonSpacing = 30;
+  constexpr int totalWidth = buttonWidth * 2 + buttonSpacing;
   const int startX = (pageWidth - totalWidth) / 2;
 
   // Draw "Yes" button
@@ -665,9 +677,9 @@ void WifiSelectionActivity::renderForgetPrompt() const {
 
   // Draw Yes/No buttons
   const int buttonY = top + 80;
-  const int buttonWidth = 60;
-  const int buttonSpacing = 30;
-  const int totalWidth = buttonWidth * 2 + buttonSpacing;
+  constexpr int buttonWidth = 60;
+  constexpr int buttonSpacing = 30;
+  constexpr int totalWidth = buttonWidth * 2 + buttonSpacing;
   const int startX = (pageWidth - totalWidth) / 2;
 
   // Draw "Yes" button

src/activities/network/WifiSelectionActivity.h

@@ -9,8 +9,7 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
-#include "../util/KeyboardEntryActivity.h"
+#include "activities/ActivityWithSubactivity.h"
 
 // Structure to hold WiFi network information
 struct WifiNetworkInfo {
@@ -43,7 +42,7 @@ enum class WifiSelectionState {
  *
  * The onComplete callback receives true if connected successfully, false if cancelled.
  */
-class WifiSelectionActivity final : public Activity {
+class WifiSelectionActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
   bool updateRequired = false;
@@ -56,9 +55,6 @@ class WifiSelectionActivity final : public Activity {
   std::string selectedSSID;
   bool selectedRequiresPassword = false;
 
-  // On-screen keyboard for password entry
-  std::unique_ptr<KeyboardEntryActivity> keyboard;
-
   // Connection result
   std::string connectedIP;
   std::string connectionError;
@@ -98,7 +94,7 @@ class WifiSelectionActivity final : public Activity {
  public:
   explicit WifiSelectionActivity(GfxRenderer& renderer, InputManager& inputManager,
                                  const std::function<void(bool connected)>& onComplete)
-      : Activity(renderer, inputManager), onComplete(onComplete) {}
+      : ActivityWithSubactivity("WifiSelection", renderer, inputManager), onComplete(onComplete) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/reader/EpubReaderActivity.cpp

@@ -1,8 +1,9 @@
 #include "EpubReaderActivity.h"
 
 #include <Epub/Page.h>
+#include <FsHelpers.h>
 #include <GfxRenderer.h>
-#include <SD.h>
+#include <InputManager.h>
 
 #include "Battery.h"
 #include "CrossPointSettings.h"
@@ -26,6 +27,8 @@ void EpubReaderActivity::taskTrampoline(void* param) {
 }
 
 void EpubReaderActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+
   if (!epub) {
     return;
   }
@@ -34,8 +37,8 @@ void EpubReaderActivity::onEnter() {
 
   epub->setupCacheDir();
 
-  File f = SD.open((epub->getCachePath() + "/progress.bin").c_str());
-  if (f) {
+  File f;
+  if (FsHelpers::openFileForRead("ERS", epub->getCachePath() + "/progress.bin", f)) {
     uint8_t data[4];
     if (f.read(data, 4) == 4) {
       currentSpineIndex = data[0] + (data[1] << 8);
@@ -61,6 +64,8 @@ void EpubReaderActivity::onEnter() {
 }
 
 void EpubReaderActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {
@@ -75,8 +80,8 @@ void EpubReaderActivity::onExit() {
 
 void EpubReaderActivity::loop() {
   // Pass input responsibility to sub activity if exists
-  if (subAcitivity) {
-    subAcitivity->loop();
+  if (subActivity) {
+    subActivity->loop();
     return;
   }
 
@@ -84,11 +89,11 @@ void EpubReaderActivity::loop() {
   if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
     // Don't start activity transition while rendering
     xSemaphoreTake(renderingMutex, portMAX_DELAY);
-    subAcitivity.reset(new EpubReaderChapterSelectionActivity(
+    exitActivity();
+    enterNewActivity(new EpubReaderChapterSelectionActivity(
         this->renderer, this->inputManager, epub, currentSpineIndex,
         [this] {
-          subAcitivity->onExit();
-          subAcitivity.reset();
+          exitActivity();
           updateRequired = true;
         },
         [this](const int newSpineIndex) {
@@ -97,11 +102,9 @@ void EpubReaderActivity::loop() {
             nextPageNumber = 0;
             section.reset();
           }
-          subAcitivity->onExit();
-          subAcitivity.reset();
+          exitActivity();
           updateRequired = true;
         }));
-    subAcitivity->onEnter();
     xSemaphoreGive(renderingMutex);
   }
 
@@ -209,7 +212,7 @@ void EpubReaderActivity::renderScreen() {
   }
 
   if (!section) {
-    const auto filepath = epub->getSpineItem(currentSpineIndex);
+    const auto filepath = epub->getSpineItem(currentSpineIndex).href;
     Serial.printf("[%lu] [ERS] Loading file: %s, index: %d\n", millis(), filepath.c_str(), currentSpineIndex);
     section = std::unique_ptr<Section>(new Section(epub, currentSpineIndex, renderer));
     if (!section->loadCacheMetadata(READER_FONT_ID, lineCompression, marginTop, marginRight, marginBottom, marginLeft,
@@ -279,7 +282,8 @@ void EpubReaderActivity::renderScreen() {
     Serial.printf("[%lu] [ERS] Rendered page in %dms\n", millis(), millis() - start);
   }
 
-  File f = SD.open((epub->getCachePath() + "/progress.bin").c_str(), FILE_WRITE);
+  File f;
+  if (FsHelpers::openFileForWrite("ERS", epub->getCachePath() + "/progress.bin", f)) {
     uint8_t data[4];
     data[0] = currentSpineIndex & 0xFF;
     data[1] = (currentSpineIndex >> 8) & 0xFF;
@@ -287,6 +291,7 @@ void EpubReaderActivity::renderScreen() {
     data[3] = (section->currentPage >> 8) & 0xFF;
     f.write(data, 4);
     f.close();
+  }
 }
 
 void EpubReaderActivity::renderContents(std::unique_ptr<Page> page) {
@@ -330,8 +335,8 @@ void EpubReaderActivity::renderStatusBar() const {
   constexpr auto textY = 776;
 
   // Calculate progress in book
-  float sectionChapterProg = static_cast<float>(section->currentPage) / section->pageCount;
-  uint8_t bookProgress = epub->calculateProgress(currentSpineIndex, sectionChapterProg);
+  const float sectionChapterProg = static_cast<float>(section->currentPage) / section->pageCount;
+  const uint8_t bookProgress = epub->calculateProgress(currentSpineIndex, sectionChapterProg);
 
   // Right aligned text for progress counter
   const std::string progress = std::to_string(section->currentPage + 1) + "/" + std::to_string(section->pageCount) +

src/activities/reader/EpubReaderActivity.h

@@ -5,14 +5,13 @@
 #include <freertos/semphr.h>
 #include <freertos/task.h>
 
-#include "../Activity.h"
+#include "activities/ActivityWithSubactivity.h"
 
-class EpubReaderActivity final : public Activity {
+class EpubReaderActivity final : public ActivityWithSubactivity {
   std::shared_ptr<Epub> epub;
   std::unique_ptr<Section> section = nullptr;
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
-  std::unique_ptr<Activity> subAcitivity = nullptr;
   int currentSpineIndex = 0;
   int nextPageNumber = 0;
   int pagesUntilFullRefresh = 0;
@@ -28,7 +27,7 @@ class EpubReaderActivity final : public Activity {
  public:
   explicit EpubReaderActivity(GfxRenderer& renderer, InputManager& inputManager, std::unique_ptr<Epub> epub,
                               const std::function<void()>& onGoBack)
-      : Activity(renderer, inputManager), epub(std::move(epub)), onGoBack(onGoBack) {}
+      : ActivityWithSubactivity("EpubReader", renderer, inputManager), epub(std::move(epub)), onGoBack(onGoBack) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/reader/EpubReaderChapterSelectionActivity.cpp

@@ -1,6 +1,7 @@
 #include "EpubReaderChapterSelectionActivity.h"
 
 #include <GfxRenderer.h>
+#include <InputManager.h>
 #include <SD.h>
 
 #include "config.h"
@@ -16,6 +17,8 @@ void EpubReaderChapterSelectionActivity::taskTrampoline(void* param) {
 }
 
 void EpubReaderChapterSelectionActivity::onEnter() {
+  Activity::onEnter();
+
   if (!epub) {
     return;
   }
@@ -26,7 +29,7 @@ void EpubReaderChapterSelectionActivity::onEnter() {
   // Trigger first update
   updateRequired = true;
   xTaskCreate(&EpubReaderChapterSelectionActivity::taskTrampoline, "EpubReaderChapterSelectionActivityTask",
-              2048,               // Stack size
+              4096,               // Stack size
               this,               // Parameters
               1,                  // Priority
               &displayTaskHandle  // Task handle
@@ -34,6 +37,8 @@ void EpubReaderChapterSelectionActivity::onEnter() {
 }
 
 void EpubReaderChapterSelectionActivity::onExit() {
+  Activity::onExit();
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {

src/activities/reader/EpubReaderChapterSelectionActivity.h

@@ -27,7 +27,7 @@ class EpubReaderChapterSelectionActivity final : public Activity {
                                               const std::shared_ptr<Epub>& epub, const int currentSpineIndex,
                                               const std::function<void()>& onGoBack,
                                               const std::function<void(int newSpineIndex)>& onSelectSpineIndex)
-      : Activity(renderer, inputManager),
+      : Activity("EpubReaderChapterSelection", renderer, inputManager),
         epub(epub),
         currentSpineIndex(currentSpineIndex),
         onGoBack(onGoBack),

src/activities/reader/FileSelectionActivity.cpp

@@ -1,6 +1,7 @@
 #include "FileSelectionActivity.h"
 
 #include <GfxRenderer.h>
+#include <InputManager.h>
 #include <SD.h>
 
 #include "config.h"
@@ -48,6 +49,8 @@ void FileSelectionActivity::loadFiles() {
 }
 
 void FileSelectionActivity::onEnter() {
+  Activity::onEnter();
+
   renderingMutex = xSemaphoreCreateMutex();
 
   basepath = "/";
@@ -66,6 +69,8 @@ void FileSelectionActivity::onEnter() {
 }
 
 void FileSelectionActivity::onExit() {
+  Activity::onExit();
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {

src/activities/reader/FileSelectionActivity.h

@@ -28,7 +28,7 @@ class FileSelectionActivity final : public Activity {
   explicit FileSelectionActivity(GfxRenderer& renderer, InputManager& inputManager,
                                  const std::function<void(const std::string&)>& onSelect,
                                  const std::function<void()>& onGoHome)
-      : Activity(renderer, inputManager), onSelect(onSelect), onGoHome(onGoHome) {}
+      : Activity("FileSelection", renderer, inputManager), onSelect(onSelect), onGoHome(onGoHome) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/reader/ReaderActivity.cpp

@@ -50,6 +50,8 @@ void ReaderActivity::onGoToEpubReader(std::unique_ptr<Epub> epub) {
 }
 
 void ReaderActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+
   if (initialEpubPath.empty()) {
     onGoToFileSelection();
     return;

src/activities/reader/ReaderActivity.h

@@ -17,7 +17,7 @@ class ReaderActivity final : public ActivityWithSubactivity {
  public:
   explicit ReaderActivity(GfxRenderer& renderer, InputManager& inputManager, std::string initialEpubPath,
                           const std::function<void()>& onGoBack)
-      : ActivityWithSubactivity(renderer, inputManager),
+      : ActivityWithSubactivity("Reader", renderer, inputManager),
         initialEpubPath(std::move(initialEpubPath)),
         onGoBack(onGoBack) {}
   void onEnter() override;

src/activities/settings/OtaUpdateActivity.cpp

@@ -0,0 +1,242 @@
+#include "OtaUpdateActivity.h"
+
+#include <GfxRenderer.h>
+#include <InputManager.h>
+#include <WiFi.h>
+
+#include "activities/network/WifiSelectionActivity.h"
+#include "config.h"
+#include "network/OtaUpdater.h"
+
+void OtaUpdateActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<OtaUpdateActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void OtaUpdateActivity::onWifiSelectionComplete(const bool success) {
+  exitActivity();
+
+  if (!success) {
+    Serial.printf("[%lu] [OTA] WiFi connection failed, exiting\n", millis());
+    goBack();
+    return;
+  }
+
+  Serial.printf("[%lu] [OTA] WiFi connected, checking for update\n", millis());
+
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  state = CHECKING_FOR_UPDATE;
+  xSemaphoreGive(renderingMutex);
+  updateRequired = true;
+  vTaskDelay(10 / portTICK_PERIOD_MS);
+  const auto res = updater.checkForUpdate();
+  if (res != OtaUpdater::OK) {
+    Serial.printf("[%lu] [OTA] Update check failed: %d\n", millis(), res);
+    xSemaphoreTake(renderingMutex, portMAX_DELAY);
+    state = FAILED;
+    xSemaphoreGive(renderingMutex);
+    updateRequired = true;
+    return;
+  }
+
+  if (!updater.isUpdateNewer()) {
+    Serial.printf("[%lu] [OTA] No new update available\n", millis());
+    xSemaphoreTake(renderingMutex, portMAX_DELAY);
+    state = NO_UPDATE;
+    xSemaphoreGive(renderingMutex);
+    updateRequired = true;
+    return;
+  }
+
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  state = WAITING_CONFIRMATION;
+  xSemaphoreGive(renderingMutex);
+  updateRequired = true;
+}
+
+void OtaUpdateActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+
+  renderingMutex = xSemaphoreCreateMutex();
+
+  xTaskCreate(&OtaUpdateActivity::taskTrampoline, "OtaUpdateActivityTask",
+              2048,               // Stack size
+              this,               // Parameters
+              1,                  // Priority
+              &displayTaskHandle  // Task handle
+  );
+
+  // Turn on WiFi immediately
+  Serial.printf("[%lu] [OTA] Turning on WiFi...\n", millis());
+  WiFi.mode(WIFI_STA);
+
+  // Launch WiFi selection subactivity
+  Serial.printf("[%lu] [OTA] Launching WifiSelectionActivity...\n", millis());
+  enterNewActivity(new WifiSelectionActivity(renderer, inputManager,
+                                             [this](const bool connected) { onWifiSelectionComplete(connected); }));
+}
+
+void OtaUpdateActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+
+  // Turn off wifi
+  WiFi.disconnect(false);  // false = don't erase credentials, send disconnect frame
+  delay(100);              // Allow disconnect frame to be sent
+  WiFi.mode(WIFI_OFF);
+  delay(100);  // Allow WiFi hardware to fully power down
+
+  // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+void OtaUpdateActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      render();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void OtaUpdateActivity::render() {
+  if (subActivity) {
+    // Subactivity handles its own rendering
+    return;
+  }
+
+  float updaterProgress = 0;
+  if (state == UPDATE_IN_PROGRESS) {
+    Serial.printf("[%lu] [OTA] Update progress: %d / %d\n", millis(), updater.processedSize, updater.totalSize);
+    updaterProgress = static_cast<float>(updater.processedSize) / static_cast<float>(updater.totalSize);
+    // Only update every 2% at the most
+    if (static_cast<int>(updaterProgress * 50) == lastUpdaterPercentage / 2) {
+      return;
+    }
+    lastUpdaterPercentage = static_cast<int>(updaterProgress * 100);
+  }
+
+  const auto pageHeight = renderer.getScreenHeight();
+  const auto pageWidth = renderer.getScreenWidth();
+
+  renderer.clearScreen();
+  renderer.drawCenteredText(READER_FONT_ID, 10, "Update", true, BOLD);
+
+  if (state == CHECKING_FOR_UPDATE) {
+    renderer.drawCenteredText(UI_FONT_ID, 300, "Checking for update...", true, BOLD);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == WAITING_CONFIRMATION) {
+    renderer.drawCenteredText(UI_FONT_ID, 200, "New update available!", true, BOLD);
+    renderer.drawText(UI_FONT_ID, 20, 250, "Current Version: " CROSSPOINT_VERSION);
+    renderer.drawText(UI_FONT_ID, 20, 270, ("New Version: " + updater.getLatestVersion()).c_str());
+
+    renderer.drawRect(25, pageHeight - 40, 106, 40);
+    renderer.drawText(UI_FONT_ID, 25 + (105 - renderer.getTextWidth(UI_FONT_ID, "Cancel")) / 2, pageHeight - 35,
+                      "Cancel");
+
+    renderer.drawRect(130, pageHeight - 40, 106, 40);
+    renderer.drawText(UI_FONT_ID, 130 + (105 - renderer.getTextWidth(UI_FONT_ID, "Update")) / 2, pageHeight - 35,
+                      "Update");
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == UPDATE_IN_PROGRESS) {
+    renderer.drawCenteredText(UI_FONT_ID, 310, "Updating...", true, BOLD);
+    renderer.drawRect(20, 350, pageWidth - 40, 50);
+    renderer.fillRect(24, 354, static_cast<int>(updaterProgress * static_cast<float>(pageWidth - 44)), 42);
+    renderer.drawCenteredText(UI_FONT_ID, 420, (std::to_string(static_cast<int>(updaterProgress * 100)) + "%").c_str());
+    renderer.drawCenteredText(
+        UI_FONT_ID, 440, (std::to_string(updater.processedSize) + " / " + std::to_string(updater.totalSize)).c_str());
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == NO_UPDATE) {
+    renderer.drawCenteredText(UI_FONT_ID, 300, "No update available", true, BOLD);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == FAILED) {
+    renderer.drawCenteredText(UI_FONT_ID, 300, "Update failed", true, BOLD);
+    renderer.displayBuffer();
+    return;
+  }
+
+  if (state == FINISHED) {
+    renderer.drawCenteredText(UI_FONT_ID, 300, "Update complete", true, BOLD);
+    renderer.drawCenteredText(UI_FONT_ID, 350, "Press and hold power button to turn back on");
+    renderer.displayBuffer();
+    state = SHUTTING_DOWN;
+    return;
+  }
+}
+
+void OtaUpdateActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
+  if (state == WAITING_CONFIRMATION) {
+    if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
+      Serial.printf("[%lu] [OTA] New update available, starting download...\n", millis());
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      state = UPDATE_IN_PROGRESS;
+      xSemaphoreGive(renderingMutex);
+      updateRequired = true;
+      vTaskDelay(10 / portTICK_PERIOD_MS);
+      const auto res = updater.installUpdate([this](const size_t, const size_t) { updateRequired = true; });
+
+      if (res != OtaUpdater::OK) {
+        Serial.printf("[%lu] [OTA] Update failed: %d\n", millis(), res);
+        xSemaphoreTake(renderingMutex, portMAX_DELAY);
+        state = FAILED;
+        xSemaphoreGive(renderingMutex);
+        updateRequired = true;
+        return;
+      }
+
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      state = FINISHED;
+      xSemaphoreGive(renderingMutex);
+      updateRequired = true;
+    }
+
+    if (inputManager.wasPressed(InputManager::BTN_BACK)) {
+      goBack();
+    }
+
+    return;
+  }
+
+  if (state == FAILED) {
+    if (inputManager.wasPressed(InputManager::BTN_BACK)) {
+      goBack();
+    }
+    return;
+  }
+
+  if (state == NO_UPDATE) {
+    if (inputManager.wasPressed(InputManager::BTN_BACK)) {
+      goBack();
+    }
+    return;
+  }
+
+  if (state == SHUTTING_DOWN) {
+    ESP.restart();
+  }
+}

src/activities/settings/OtaUpdateActivity.h

@@ -0,0 +1,43 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include "activities/ActivityWithSubactivity.h"
+#include "network/OtaUpdater.h"
+
+class OtaUpdateActivity : public ActivityWithSubactivity {
+  enum State {
+    WIFI_SELECTION,
+    CHECKING_FOR_UPDATE,
+    WAITING_CONFIRMATION,
+    UPDATE_IN_PROGRESS,
+    NO_UPDATE,
+    FAILED,
+    FINISHED,
+    SHUTTING_DOWN
+  };
+
+  // Can't initialize this to 0 or the first render doesn't happen
+  static constexpr unsigned int UNINITIALIZED_PERCENTAGE = 111;
+
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+  bool updateRequired = false;
+  const std::function<void()> goBack;
+  State state = WIFI_SELECTION;
+  unsigned int lastUpdaterPercentage = UNINITIALIZED_PERCENTAGE;
+  OtaUpdater updater;
+
+  void onWifiSelectionComplete(bool success);
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+  void render();
+
+ public:
+  explicit OtaUpdateActivity(GfxRenderer& renderer, InputManager& inputManager, const std::function<void()>& goBack)
+      : ActivityWithSubactivity("OtaUpdate", renderer, inputManager), goBack(goBack), updater() {}
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+};

src/activities/settings/SettingsActivity.cpp

@@ -1,18 +1,22 @@
 #include "SettingsActivity.h"
 
 #include <GfxRenderer.h>
+#include <InputManager.h>
 
 #include "CrossPointSettings.h"
+#include "OtaUpdateActivity.h"
 #include "config.h"
 
 // Define the static settings list
 namespace {
-constexpr int settingsCount = 3;
+constexpr int settingsCount = 4;
 const SettingInfo settingsList[settingsCount] = {
     // Should match with SLEEP_SCREEN_MODE
     {"Sleep Screen", SettingType::ENUM, &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover"}},
     {"Extra Paragraph Spacing", SettingType::TOGGLE, &CrossPointSettings::extraParagraphSpacing, {}},
-    {"Short Power Button Click", SettingType::TOGGLE, &CrossPointSettings::shortPwrBtn, {}}};
+    {"Short Power Button Click", SettingType::TOGGLE, &CrossPointSettings::shortPwrBtn, {}},
+    {"Check for updates", SettingType::ACTION, nullptr, {}},
+};
 }  // namespace
 
 void SettingsActivity::taskTrampoline(void* param) {
@@ -21,6 +25,8 @@ void SettingsActivity::taskTrampoline(void* param) {
 }
 
 void SettingsActivity::onEnter() {
+  Activity::onEnter();
+
   renderingMutex = xSemaphoreCreateMutex();
 
   // Reset selection to first item
@@ -38,6 +44,8 @@ void SettingsActivity::onEnter() {
 }
 
 void SettingsActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+
   // Wait until not rendering to delete task to avoid killing mid-instruction to EPD
   xSemaphoreTake(renderingMutex, portMAX_DELAY);
   if (displayTaskHandle) {
@@ -49,6 +57,11 @@ void SettingsActivity::onExit() {
 }
 
 void SettingsActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
   // Handle actions with early return
   if (inputManager.wasPressed(InputManager::BTN_CONFIRM)) {
     toggleCurrentSetting();
@@ -91,6 +104,16 @@ void SettingsActivity::toggleCurrentSetting() {
   } else if (setting.type == SettingType::ENUM && setting.valuePtr != nullptr) {
     const uint8_t currentValue = SETTINGS.*(setting.valuePtr);
     SETTINGS.*(setting.valuePtr) = (currentValue + 1) % static_cast<uint8_t>(setting.enumValues.size());
+  } else if (setting.type == SettingType::ACTION) {
+    if (std::string(setting.name) == "Check for updates") {
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      exitActivity();
+      enterNewActivity(new OtaUpdateActivity(renderer, inputManager, [this] {
+        exitActivity();
+        updateRequired = true;
+      }));
+      xSemaphoreGive(renderingMutex);
+    }
   } else {
     // Only toggle if it's a toggle type and has a value pointer
     return;
@@ -102,7 +125,7 @@ void SettingsActivity::toggleCurrentSetting() {
 
 void SettingsActivity::displayTaskLoop() {
   while (true) {
-    if (updateRequired) {
+    if (updateRequired && !subActivity) {
       updateRequired = false;
       xSemaphoreTake(renderingMutex, portMAX_DELAY);
       render();
@@ -147,6 +170,8 @@ void SettingsActivity::render() const {
 
   // Draw help text
   renderer.drawText(SMALL_FONT_ID, 20, pageHeight - 30, "Press OK to toggle, BACK to save & exit");
+  renderer.drawText(SMALL_FONT_ID, pageWidth - 20 - renderer.getTextWidth(SMALL_FONT_ID, CROSSPOINT_VERSION),
+                    pageHeight - 30, CROSSPOINT_VERSION);
 
   // Always use standard refresh for settings screen
   renderer.displayBuffer();

src/activities/settings/SettingsActivity.h

@@ -3,16 +3,15 @@
 #include <freertos/semphr.h>
 #include <freertos/task.h>
 
-#include <cstdint>
 #include <functional>
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
+#include "activities/ActivityWithSubactivity.h"
 
 class CrossPointSettings;
 
-enum class SettingType { TOGGLE, ENUM };
+enum class SettingType { TOGGLE, ENUM, ACTION };
 
 // Structure to hold setting information
 struct SettingInfo {
@@ -22,7 +21,7 @@ struct SettingInfo {
   std::vector<std::string> enumValues;
 };
 
-class SettingsActivity final : public Activity {
+class SettingsActivity final : public ActivityWithSubactivity {
   TaskHandle_t displayTaskHandle = nullptr;
   SemaphoreHandle_t renderingMutex = nullptr;
   bool updateRequired = false;
@@ -36,7 +35,7 @@ class SettingsActivity final : public Activity {
 
  public:
   explicit SettingsActivity(GfxRenderer& renderer, InputManager& inputManager, const std::function<void()>& onGoHome)
-      : Activity(renderer, inputManager), onGoHome(onGoHome) {}
+      : ActivityWithSubactivity("Settings", renderer, inputManager), onGoHome(onGoHome) {}
   void onEnter() override;
   void onExit() override;
   void loop() override;

src/activities/util/FullScreenMessageActivity.cpp

@@ -5,6 +5,8 @@
 #include "config.h"
 
 void FullScreenMessageActivity::onEnter() {
+  Activity::onEnter();
+
   const auto height = renderer.getLineHeight(UI_FONT_ID);
   const auto top = (GfxRenderer::getScreenHeight() - height) / 2;
 

src/activities/util/FullScreenMessageActivity.h

@@ -16,6 +16,9 @@ class FullScreenMessageActivity final : public Activity {
   explicit FullScreenMessageActivity(GfxRenderer& renderer, InputManager& inputManager, std::string text,
                                      const EpdFontStyle style = REGULAR,
                                      const EInkDisplay::RefreshMode refreshMode = EInkDisplay::FAST_REFRESH)
-      : Activity(renderer, inputManager), text(std::move(text)), style(style), refreshMode(refreshMode) {}
+      : Activity("FullScreenMessage", renderer, inputManager),
+        text(std::move(text)),
+        style(style),
+        refreshMode(refreshMode) {}
   void onEnter() override;
 };

src/activities/util/KeyboardEntryActivity.cpp

@@ -12,11 +12,6 @@ const char* const KeyboardEntryActivity::keyboard[NUM_ROWS] = {
 const char* const KeyboardEntryActivity::keyboardShift[NUM_ROWS] = {"~!@#$%^&*()_+", "QWERTYUIOP{}|", "ASDFGHJKL:\"",
                                                                     "ZXCVBNM<>?", "^  _____<OK"};
 
-KeyboardEntryActivity::KeyboardEntryActivity(GfxRenderer& renderer, InputManager& inputManager,
-                                             const std::string& title, const std::string& initialText, size_t maxLength,
-                                             bool isPassword)
-    : Activity(renderer, inputManager), title(title), text(initialText), maxLength(maxLength), isPassword(isPassword) {}
-
 void KeyboardEntryActivity::setText(const std::string& newText) {
   text = newText;
   if (maxLength > 0 && text.length() > maxLength) {
@@ -37,15 +32,13 @@ void KeyboardEntryActivity::reset(const std::string& newTitle, const std::string
 }
 
 void KeyboardEntryActivity::onEnter() {
+  Activity::onEnter();
+
   // Reset state when entering the activity
   complete = false;
   cancelled = false;
 }
 
-void KeyboardEntryActivity::onExit() {
-  // Clean up if needed
-}
-
 void KeyboardEntryActivity::loop() {
   handleInput();
   render(10);

src/activities/util/KeyboardEntryActivity.h

@@ -34,7 +34,12 @@ class KeyboardEntryActivity : public Activity {
    * @param isPassword If true, display asterisks instead of actual characters
    */
   KeyboardEntryActivity(GfxRenderer& renderer, InputManager& inputManager, const std::string& title = "Enter Text",
-                        const std::string& initialText = "", size_t maxLength = 0, bool isPassword = false);
+                        const std::string& initialText = "", const size_t maxLength = 0, const bool isPassword = false)
+      : Activity("KeyboardEntry", renderer, inputManager),
+        title(title),
+        text(initialText),
+        maxLength(maxLength),
+        isPassword(isPassword) {}
 
   /**
    * Handle button input. Call this in your main loop.
@@ -85,7 +90,6 @@ class KeyboardEntryActivity : public Activity {
 
   // Activity overrides
   void onEnter() override;
-  void onExit() override;
   void loop() override;
 
  private:

src/html/FilesPageFooter.html

@@ -1,233 +0,0 @@
-   <div class="card">
-    <p style="text-align: center; color: #95a5a6; margin: 0;">
-      CrossPoint E-Reader • Open Source
-    </p>
-  </div>
-
-  <!-- Upload Modal -->
-  <div class="modal-overlay" id="uploadModal">
-    <div class="modal">
-      <button class="modal-close" onclick="closeUploadModal()">&times;</button>
-      <h3>📤 Upload file</h3>
-      <div class="upload-form">
-        <p class="file-info">Select a file to upload to <strong id="uploadPathDisplay"></strong></p>
-        <input type="file" id="fileInput" onchange="validateFile()">
-        <button id="uploadBtn" class="upload-btn" onclick="uploadFile()" disabled>Upload</button>
-        <div id="progress-container">
-          <div id="progress-bar"><div id="progress-fill"></div></div>
-          <div id="progress-text"></div>
-        </div>
-      </div>
-    </div>
-  </div>
-
-  <!-- New Folder Modal -->
-  <div class="modal-overlay" id="folderModal">
-    <div class="modal">
-      <button class="modal-close" onclick="closeFolderModal()">&times;</button>
-      <h3>📁 New Folder</h3>
-      <div class="folder-form">
-        <p class="file-info">Create a new folder in <strong id="folderPathDisplay"></strong></p>
-        <input type="text" id="folderName" class="folder-input" placeholder="Folder name...">
-        <button class="folder-btn" onclick="createFolder()">Create Folder</button>
-      </div>
-    </div>
-  </div>
-
-  <!-- Delete Confirmation Modal -->
-  <div class="modal-overlay" id="deleteModal">
-    <div class="modal">
-      <button class="modal-close" onclick="closeDeleteModal()">&times;</button>
-      <h3>🗑️ Delete Item</h3>
-      <div class="folder-form">
-        <p class="delete-warning">⚠️ This action cannot be undone!</p>
-        <p class="file-info">Are you sure you want to delete:</p>
-        <p class="delete-item-name" id="deleteItemName"></p>
-        <input type="hidden" id="deleteItemPath">
-        <input type="hidden" id="deleteItemType">
-        <button class="delete-btn-confirm" onclick="confirmDelete()">Delete</button>
-        <button class="delete-btn-cancel" onclick="closeDeleteModal()">Cancel</button>
-      </div>
-    </div>
-  </div>
-
-  <script>
-    // Modal functions
-    function openUploadModal() {
-      const currentPath = document.getElementById('currentPath').value;
-      document.getElementById('uploadPathDisplay').textContent = currentPath === '/' ? '/ 🏠' : currentPath;
-      document.getElementById('uploadModal').classList.add('open');
-    }
-
-    function closeUploadModal() {
-      document.getElementById('uploadModal').classList.remove('open');
-      document.getElementById('fileInput').value = '';
-      document.getElementById('uploadBtn').disabled = true;
-      document.getElementById('progress-container').style.display = 'none';
-      document.getElementById('progress-fill').style.width = '0%';
-      document.getElementById('progress-fill').style.backgroundColor = '#27ae60';
-    }
-
-    function openFolderModal() {
-      const currentPath = document.getElementById('currentPath').value;
-      document.getElementById('folderPathDisplay').textContent = currentPath === '/' ? '/ 🏠' : currentPath;
-      document.getElementById('folderModal').classList.add('open');
-      document.getElementById('folderName').value = '';
-    }
-
-    function closeFolderModal() {
-      document.getElementById('folderModal').classList.remove('open');
-    }
-
-    // Close modals when clicking overlay
-    document.querySelectorAll('.modal-overlay').forEach(function(overlay) {
-      overlay.addEventListener('click', function(e) {
-        if (e.target === overlay) {
-          overlay.classList.remove('open');
-        }
-      });
-    });
-
-    function validateFile() {
-      const fileInput = document.getElementById('fileInput');
-      const uploadBtn = document.getElementById('uploadBtn');
-      const file = fileInput.files[0];
-      uploadBtn.disabled = !file;
-    }
-
-    function uploadFile() {
-      const fileInput = document.getElementById('fileInput');
-      const file = fileInput.files[0];
-      const currentPath = document.getElementById('currentPath').value;
-
-      if (!file) {
-        alert('Please select a file first!');
-        return;
-      }
-
-      const formData = new FormData();
-      formData.append('file', file);
-
-      const progressContainer = document.getElementById('progress-container');
-      const progressFill = document.getElementById('progress-fill');
-      const progressText = document.getElementById('progress-text');
-      const uploadBtn = document.getElementById('uploadBtn');
-
-      progressContainer.style.display = 'block';
-      uploadBtn.disabled = true;
-
-      const xhr = new XMLHttpRequest();
-      // Include path as query parameter since multipart form data doesn't make
-      // form fields available until after file upload completes
-      xhr.open('POST', '/upload?path=' + encodeURIComponent(currentPath), true);
-
-      xhr.upload.onprogress = function(e) {
-        if (e.lengthComputable) {
-          const percent = Math.round((e.loaded / e.total) * 100);
-          progressFill.style.width = percent + '%';
-          progressText.textContent = 'Uploading: ' + percent + '%';
-        }
-      };
-
-      xhr.onload = function() {
-        if (xhr.status === 200) {
-          progressText.textContent = 'Upload complete!';
-          setTimeout(function() {
-            window.location.reload();
-          }, 1000);
-        } else {
-          progressText.textContent = 'Upload failed: ' + xhr.responseText;
-          progressFill.style.backgroundColor = '#e74c3c';
-          uploadBtn.disabled = false;
-        }
-      };
-
-      xhr.onerror = function() {
-        progressText.textContent = 'Upload failed - network error';
-        progressFill.style.backgroundColor = '#e74c3c';
-        uploadBtn.disabled = false;
-      };
-
-      xhr.send(formData);
-    }
-
-    function createFolder() {
-      const folderName = document.getElementById('folderName').value.trim();
-      const currentPath = document.getElementById('currentPath').value;
-
-      if (!folderName) {
-        alert('Please enter a folder name!');
-        return;
-      }
-
-      // Validate folder name (no special characters except underscore and hyphen)
-      const validName = /^[a-zA-Z0-9_\-]+$/.test(folderName);
-      if (!validName) {
-        alert('Folder name can only contain letters, numbers, underscores, and hyphens.');
-        return;
-      }
-
-      const formData = new FormData();
-      formData.append('name', folderName);
-      formData.append('path', currentPath);
-
-      const xhr = new XMLHttpRequest();
-      xhr.open('POST', '/mkdir', true);
-
-      xhr.onload = function() {
-        if (xhr.status === 200) {
-          window.location.reload();
-        } else {
-          alert('Failed to create folder: ' + xhr.responseText);
-        }
-      };
-
-      xhr.onerror = function() {
-        alert('Failed to create folder - network error');
-      };
-
-      xhr.send(formData);
-    }
-
-    // Delete functions
-    function openDeleteModal(name, path, isFolder) {
-      document.getElementById('deleteItemName').textContent = (isFolder ? '📁 ' : '📄 ') + name;
-      document.getElementById('deleteItemPath').value = path;
-      document.getElementById('deleteItemType').value = isFolder ? 'folder' : 'file';
-      document.getElementById('deleteModal').classList.add('open');
-    }
-
-    function closeDeleteModal() {
-      document.getElementById('deleteModal').classList.remove('open');
-    }
-
-    function confirmDelete() {
-      const path = document.getElementById('deleteItemPath').value;
-      const itemType = document.getElementById('deleteItemType').value;
-
-      const formData = new FormData();
-      formData.append('path', path);
-      formData.append('type', itemType);
-
-      const xhr = new XMLHttpRequest();
-      xhr.open('POST', '/delete', true);
-
-      xhr.onload = function() {
-        if (xhr.status === 200) {
-          window.location.reload();
-        } else {
-          alert('Failed to delete: ' + xhr.responseText);
-          closeDeleteModal();
-        }
-      };
-
-      xhr.onerror = function() {
-        alert('Failed to delete - network error');
-        closeDeleteModal();
-      };
-
-      xhr.send(formData);
-    }
-  </script>
-</body>
-</html>

src/html/FilesPageHeader.html

@@ -1,472 +0,0 @@
-<!DOCTYPE html>
-<html>
-  <head>
-    <meta charset="UTF-8" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>CrossPoint Reader - Files</title>
-    <style>
-      body {
-        font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
-          Oxygen, Ubuntu, sans-serif;
-        max-width: 800px;
-        margin: 0 auto;
-        padding: 20px;
-        background-color: #f5f5f5;
-        color: #333;
-      }
-      h1 {
-        color: #2c3e50;
-        margin-bottom: 5px;
-      }
-      h2 {
-        color: #34495e;
-        margin-top: 0;
-      }
-      .card {
-        background: white;
-        border-radius: 8px;
-        padding: 20px;
-        margin: 15px 0;
-        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
-      }
-      .page-header {
-        display: flex;
-        justify-content: space-between;
-        align-items: center;
-        flex-wrap: wrap;
-        gap: 15px;
-        margin-bottom: 20px;
-        padding-bottom: 15px;
-        border-bottom: 2px solid #3498db;
-      }
-      .page-header-left {
-        display: flex;
-        align-items: baseline;
-        gap: 12px;
-        flex-wrap: wrap;
-      }
-      .breadcrumb-inline {
-        color: #7f8c8d;
-        font-size: 1.1em;
-      }
-      .breadcrumb-inline a {
-        color: #3498db;
-        text-decoration: none;
-      }
-      .breadcrumb-inline a:hover {
-        text-decoration: underline;
-      }
-      .breadcrumb-inline .sep {
-        margin: 0 6px;
-        color: #bdc3c7;
-      }
-      .breadcrumb-inline .current {
-        color: #2c3e50;
-        font-weight: 500;
-      }
-      .nav-links {
-        margin: 20px 0;
-      }
-      .nav-links a {
-        display: inline-block;
-        padding: 10px 20px;
-        background-color: #3498db;
-        color: white;
-        text-decoration: none;
-        border-radius: 4px;
-        margin-right: 10px;
-      }
-      .nav-links a:hover {
-        background-color: #2980b9;
-      }
-      /* Action buttons */
-      .action-buttons {
-        display: flex;
-        gap: 10px;
-      }
-      .action-btn {
-        color: white;
-        padding: 10px 16px;
-        border: none;
-        border-radius: 4px;
-        cursor: pointer;
-        font-size: 0.95em;
-        font-weight: 600;
-        display: flex;
-        align-items: center;
-        gap: 6px;
-      }
-      .upload-action-btn {
-        background-color: #27ae60;
-      }
-      .upload-action-btn:hover {
-        background-color: #219a52;
-      }
-      .folder-action-btn {
-        background-color: #f39c12;
-      }
-      .folder-action-btn:hover {
-        background-color: #d68910;
-      }
-      /* Upload modal */
-      .modal-overlay {
-        display: none;
-        position: fixed;
-        top: 0;
-        left: 0;
-        right: 0;
-        bottom: 0;
-        background: rgba(0, 0, 0, 0.5);
-        z-index: 200;
-        justify-content: center;
-        align-items: center;
-      }
-      .modal-overlay.open {
-        display: flex;
-      }
-      .modal {
-        background: white;
-        border-radius: 8px;
-        padding: 25px;
-        max-width: 450px;
-        width: 90%;
-        box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
-      }
-      .modal h3 {
-        margin: 0 0 15px 0;
-        color: #2c3e50;
-      }
-      .modal-close {
-        float: right;
-        background: none;
-        border: none;
-        font-size: 1.5em;
-        cursor: pointer;
-        color: #7f8c8d;
-        line-height: 1;
-      }
-      .modal-close:hover {
-        color: #2c3e50;
-      }
-      .file-table {
-        width: 100%;
-        border-collapse: collapse;
-      }
-      .file-table th,
-      .file-table td {
-        padding: 12px;
-        text-align: left;
-        border-bottom: 1px solid #eee;
-      }
-      .file-table th {
-        background-color: #f8f9fa;
-        font-weight: 600;
-        color: #7f8c8d;
-      }
-      .file-table tr:hover {
-        background-color: #f8f9fa;
-      }
-      .epub-file {
-        background-color: #e8f6e9 !important;
-      }
-      .epub-file:hover {
-        background-color: #d4edda !important;
-      }
-      .folder-row {
-        background-color: #fff9e6 !important;
-      }
-      .folder-row:hover {
-        background-color: #fff3cd !important;
-      }
-      .epub-badge {
-        display: inline-block;
-        padding: 2px 8px;
-        background-color: #27ae60;
-        color: white;
-        border-radius: 10px;
-        font-size: 0.75em;
-        margin-left: 8px;
-      }
-      .folder-badge {
-        display: inline-block;
-        padding: 2px 8px;
-        background-color: #f39c12;
-        color: white;
-        border-radius: 10px;
-        font-size: 0.75em;
-        margin-left: 8px;
-      }
-      .file-icon {
-        margin-right: 8px;
-      }
-      .folder-link {
-        color: #2c3e50;
-        text-decoration: none;
-        cursor: pointer;
-      }
-      .folder-link:hover {
-        color: #3498db;
-        text-decoration: underline;
-      }
-      .upload-form {
-        margin-top: 10px;
-      }
-      .upload-form input[type="file"] {
-        margin: 10px 0;
-        width: 100%;
-      }
-      .upload-btn {
-        background-color: #27ae60;
-        color: white;
-        padding: 10px 20px;
-        border: none;
-        border-radius: 4px;
-        cursor: pointer;
-        font-size: 1em;
-        width: 100%;
-      }
-      .upload-btn:hover {
-        background-color: #219a52;
-      }
-      .upload-btn:disabled {
-        background-color: #95a5a6;
-        cursor: not-allowed;
-      }
-      .file-info {
-        color: #7f8c8d;
-        font-size: 0.85em;
-        margin: 8px 0;
-      }
-      .no-files {
-        text-align: center;
-        color: #95a5a6;
-        padding: 40px;
-        font-style: italic;
-      }
-      .message {
-        padding: 15px;
-        border-radius: 4px;
-        margin: 15px 0;
-      }
-      .message.success {
-        background-color: #d4edda;
-        color: #155724;
-        border: 1px solid #c3e6cb;
-      }
-      .message.error {
-        background-color: #f8d7da;
-        color: #721c24;
-        border: 1px solid #f5c6cb;
-      }
-      .contents-header {
-        display: flex;
-        justify-content: space-between;
-        align-items: center;
-        margin-bottom: 12px;
-      }
-      .contents-title {
-        font-size: 1.1em;
-        font-weight: 600;
-        color: #34495e;
-        margin: 0;
-      }
-      .summary-inline {
-        color: #7f8c8d;
-        font-size: 0.9em;
-      }
-      #progress-container {
-        display: none;
-        margin-top: 10px;
-      }
-      #progress-bar {
-        width: 100%;
-        height: 20px;
-        background-color: #e0e0e0;
-        border-radius: 10px;
-        overflow: hidden;
-      }
-      #progress-fill {
-        height: 100%;
-        background-color: #27ae60;
-        width: 0%;
-        transition: width 0.3s;
-      }
-      #progress-text {
-        text-align: center;
-        margin-top: 5px;
-        font-size: 0.9em;
-        color: #7f8c8d;
-      }
-      .folder-form {
-        margin-top: 10px;
-      }
-      .folder-input {
-        width: 100%;
-        padding: 10px;
-        border: 1px solid #ddd;
-        border-radius: 4px;
-        font-size: 1em;
-        margin-bottom: 10px;
-        box-sizing: border-box;
-      }
-      .folder-btn {
-        background-color: #f39c12;
-        color: white;
-        padding: 10px 20px;
-        border: none;
-        border-radius: 4px;
-        cursor: pointer;
-        font-size: 1em;
-        width: 100%;
-      }
-      .folder-btn:hover {
-        background-color: #d68910;
-      }
-      /* Delete button styles */
-      .delete-btn {
-        background: none;
-        border: none;
-        cursor: pointer;
-        font-size: 1.1em;
-        padding: 4px 8px;
-        border-radius: 4px;
-        color: #95a5a6;
-        transition: all 0.15s;
-      }
-      .delete-btn:hover {
-        background-color: #fee;
-        color: #e74c3c;
-      }
-      .actions-col {
-        width: 60px;
-        text-align: center;
-      }
-      /* Delete modal */
-      .delete-warning {
-        color: #e74c3c;
-        font-weight: 600;
-        margin: 10px 0;
-      }
-      .delete-item-name {
-        font-weight: 600;
-        color: #2c3e50;
-        word-break: break-all;
-      }
-      .delete-btn-confirm {
-        background-color: #e74c3c;
-        color: white;
-        padding: 10px 20px;
-        border: none;
-        border-radius: 4px;
-        cursor: pointer;
-        font-size: 1em;
-        width: 100%;
-      }
-      .delete-btn-confirm:hover {
-        background-color: #c0392b;
-      }
-      .delete-btn-cancel {
-        background-color: #95a5a6;
-        color: white;
-        padding: 10px 20px;
-        border: none;
-        border-radius: 4px;
-        cursor: pointer;
-        font-size: 1em;
-        width: 100%;
-        margin-top: 10px;
-      }
-      .delete-btn-cancel:hover {
-        background-color: #7f8c8d;
-      }
-      /* Mobile responsive styles */
-      @media (max-width: 600px) {
-        body {
-          padding: 10px;
-          font-size: 14px;
-        }
-        .card {
-          padding: 12px;
-          margin: 10px 0;
-        }
-        .page-header {
-          gap: 10px;
-          margin-bottom: 12px;
-          padding-bottom: 10px;
-        }
-        .page-header-left {
-          gap: 8px;
-        }
-        h1 {
-          font-size: 1.3em;
-        }
-        .breadcrumb-inline {
-          font-size: 0.95em;
-        }
-        .nav-links a {
-          padding: 8px 12px;
-          margin-right: 6px;
-          font-size: 0.9em;
-        }
-        .action-buttons {
-          gap: 6px;
-        }
-        .action-btn {
-          padding: 8px 10px;
-          font-size: 0.85em;
-        }
-        .file-table th,
-        .file-table td {
-          padding: 8px 6px;
-          font-size: 0.9em;
-        }
-        .file-table th {
-          font-size: 0.85em;
-        }
-        .file-icon {
-          margin-right: 4px;
-        }
-        .epub-badge,
-        .folder-badge {
-          padding: 2px 5px;
-          font-size: 0.65em;
-          margin-left: 4px;
-        }
-        .contents-header {
-          margin-bottom: 8px;
-          flex-wrap: wrap;
-          gap: 4px;
-        }
-        .contents-title {
-          font-size: 1em;
-        }
-        .summary-inline {
-          font-size: 0.8em;
-        }
-        .modal {
-          padding: 15px;
-        }
-        .modal h3 {
-          font-size: 1.1em;
-        }
-        .actions-col {
-          width: 40px;
-        }
-        .delete-btn {
-          font-size: 1em;
-          padding: 2px 4px;
-        }
-        .no-files {
-          padding: 20px;
-          font-size: 0.9em;
-        }
-      }
-    </style>
-  </head>
-  <body>
-    <div class="nav-links">
-      <a href="/">Home</a>
-      <a href="/files">File Manager</a>
-    </div>
-  </body>
-</html>

src/main.cpp

@@ -60,6 +60,9 @@ EpdFontFamily ubuntuFontFamily(&ubuntu10Font, &ubuntuBold10Font);
 
 // Auto-sleep timeout (10 minutes of inactivity)
 constexpr unsigned long AUTO_SLEEP_TIMEOUT_MS = 10 * 60 * 1000;
+// measurement of power button press duration calibration value
+unsigned long t1 = 0;
+unsigned long t2 = 0;
 
 void exitActivity() {
   if (currentActivity) {
@@ -79,6 +82,10 @@ void verifyWakeupLongPress() {
   // Give the user up to 1000ms to start holding the power button, and must hold for SETTINGS.getPowerButtonDuration()
   const auto start = millis();
   bool abort = false;
+  // It takes us some time to wake up from deep sleep, so we need to subtract that from the duration
+  uint16_t calibration = 25;
+  uint16_t calibratedPressDuration =
+      (calibration < SETTINGS.getPowerButtonDuration()) ? SETTINGS.getPowerButtonDuration() - calibration : 1;
 
   inputManager.update();
   // Verify the user has actually pressed
@@ -87,13 +94,13 @@ void verifyWakeupLongPress() {
     inputManager.update();
   }
 
+  t2 = millis();
   if (inputManager.isPressed(InputManager::BTN_POWER)) {
     do {
       delay(10);
       inputManager.update();
-    } while (inputManager.isPressed(InputManager::BTN_POWER) &&
-             inputManager.getHeldTime() < SETTINGS.getPowerButtonDuration());
-    abort = inputManager.getHeldTime() < SETTINGS.getPowerButtonDuration();
+    } while (inputManager.isPressed(InputManager::BTN_POWER) && inputManager.getHeldTime() < calibratedPressDuration);
+    abort = inputManager.getHeldTime() < calibratedPressDuration;
   } else {
     abort = true;
   }
@@ -119,14 +126,12 @@ void enterDeepSleep() {
   exitActivity();
   enterNewActivity(new SleepActivity(renderer, inputManager));
 
-  Serial.printf("[%lu] [   ] Entering deep sleep.\n", millis());
-  delay(1000);  // Allow Serial buffer to empty and display to update
-
-  // Enable Wakeup on LOW (button press)
-  esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
-
   einkDisplay.deepSleep();
-
+  Serial.printf("[%lu] [   ] Power button press calibration value: %lu ms\n", millis(), t2 - t1);
+  Serial.printf("[%lu] [   ] Entering deep sleep.\n", millis());
+  esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
+  // Ensure that the power button has been released to avoid immediately turning back on if you're holding it
+  waitForPowerRelease();
   // Enter Deep Sleep
   esp_deep_sleep_start();
 }
@@ -153,8 +158,23 @@ void onGoHome() {
   enterNewActivity(new HomeActivity(renderer, inputManager, onGoToReaderHome, onGoToSettings, onGoToFileTransfer));
 }
 
+void setupDisplayAndFonts() {
+  einkDisplay.begin();
+  Serial.printf("[%lu] [   ] Display initialized\n", millis());
+  renderer.insertFont(READER_FONT_ID, bookerlyFontFamily);
+  renderer.insertFont(UI_FONT_ID, ubuntuFontFamily);
+  renderer.insertFont(SMALL_FONT_ID, smallFontFamily);
+  Serial.printf("[%lu] [   ] Fonts setup\n", millis());
+}
+
 void setup() {
+  t1 = millis();
+
+  // Only start serial if USB connected
+  pinMode(UART0_RXD, INPUT);
+  if (digitalRead(UART0_RXD) == HIGH) {
     Serial.begin(115200);
+  }
 
   Serial.printf("[%lu] [   ] Starting CrossPoint version " CROSSPOINT_VERSION "\n", millis());
 
@@ -166,8 +186,10 @@ void setup() {
   SPI.begin(EPD_SCLK, SD_SPI_MISO, EPD_MOSI, EPD_CS);
 
   // SD Card Initialization
-  if (!SD.begin(SD_SPI_CS, SPI, SPI_FQ)) {
+  // We need 6 open files concurrently when parsing a new chapter
+  if (!SD.begin(SD_SPI_CS, SPI, SPI_FQ, "/sd", 6)) {
     Serial.printf("[%lu] [   ] SD card initialization failed\n", millis());
+    setupDisplayAndFonts();
     exitActivity();
     enterNewActivity(new FullScreenMessageActivity(renderer, inputManager, "SD card error", BOLD));
     return;
@@ -178,14 +200,7 @@ void setup() {
   // verify power button press duration after we've read settings.
   verifyWakeupLongPress();
 
-  // Initialize display
-  einkDisplay.begin();
-  Serial.printf("[%lu] [   ] Display initialized\n", millis());
-
-  renderer.insertFont(READER_FONT_ID, bookerlyFontFamily);
-  renderer.insertFont(UI_FONT_ID, ubuntuFontFamily);
-  renderer.insertFont(SMALL_FONT_ID, smallFontFamily);
-  Serial.printf("[%lu] [   ] Fonts setup\n", millis());
+  setupDisplayAndFonts();
 
   exitActivity();
   enterNewActivity(new BootActivity(renderer, inputManager));
@@ -231,7 +246,7 @@ void loop() {
     return;
   }
 
-  if (inputManager.wasReleased(InputManager::BTN_POWER) &&
+  if (inputManager.isPressed(InputManager::BTN_POWER) &&
       inputManager.getHeldTime() > SETTINGS.getPowerButtonDuration()) {
     enterDeepSleep();
     // This should never be hit as `enterDeepSleep` calls esp_deep_sleep_start

src/network/CrossPointWebServer.cpp

@@ -1,53 +1,20 @@
 #include "CrossPointWebServer.h"
 
+#include <ArduinoJson.h>
+#include <FsHelpers.h>
 #include <SD.h>
 #include <WiFi.h>
 
 #include <algorithm>
 
-#include "config.h"
-#include "html/FilesPageFooterHtml.generated.h"
-#include "html/FilesPageHeaderHtml.generated.h"
+#include "html/FilesPageHtml.generated.h"
 #include "html/HomePageHtml.generated.h"
 
 namespace {
-
 // Folders/files to hide from the web interface file browser
 // Note: Items starting with "." are automatically hidden
 const char* HIDDEN_ITEMS[] = {"System Volume Information", "XTCache"};
-const size_t HIDDEN_ITEMS_COUNT = sizeof(HIDDEN_ITEMS) / sizeof(HIDDEN_ITEMS[0]);
-
-// Helper function to escape HTML special characters to prevent XSS
-String escapeHtml(const String& input) {
-  String output;
-  output.reserve(input.length() * 1.1);  // Pre-allocate with some extra space
-
-  for (size_t i = 0; i < input.length(); i++) {
-    char c = input.charAt(i);
-    switch (c) {
-      case '&':
-        output += "&amp;";
-        break;
-      case '<':
-        output += "&lt;";
-        break;
-      case '>':
-        output += "&gt;";
-        break;
-      case '"':
-        output += "&quot;";
-        break;
-      case '\'':
-        output += "&#39;";
-        break;
-      default:
-        output += c;
-        break;
-    }
-  }
-  return output;
-}
-
+constexpr size_t HIDDEN_ITEMS_COUNT = sizeof(HIDDEN_ITEMS) / sizeof(HIDDEN_ITEMS[0]);
 }  // namespace
 
 // File listing page template - now using generated headers:
@@ -64,15 +31,25 @@ void CrossPointWebServer::begin() {
     return;
   }
 
-  if (WiFi.status() != WL_CONNECTED) {
-    Serial.printf("[%lu] [WEB] Cannot start webserver - WiFi not connected\n", millis());
+  // Check if we have a valid network connection (either STA connected or AP mode)
+  const wifi_mode_t wifiMode = WiFi.getMode();
+  const bool isStaConnected = (wifiMode & WIFI_MODE_STA) && (WiFi.status() == WL_CONNECTED);
+  const bool isInApMode = (wifiMode & WIFI_MODE_AP) && (WiFi.softAPgetStationNum() >= 0);  // AP is running
+
+  if (!isStaConnected && !isInApMode) {
+    Serial.printf("[%lu] [WEB] Cannot start webserver - no valid network (mode=%d, status=%d)\n", millis(), wifiMode,
+                  WiFi.status());
     return;
   }
 
+  // Store AP mode flag for later use (e.g., in handleStatus)
+  apMode = isInApMode;
+
   Serial.printf("[%lu] [WEB] [MEM] Free heap before begin: %d bytes\n", millis(), ESP.getFreeHeap());
+  Serial.printf("[%lu] [WEB] Network mode: %s\n", millis(), apMode ? "AP" : "STA");
 
   Serial.printf("[%lu] [WEB] Creating web server on port %d...\n", millis(), port);
-  server = new WebServer(port);
+  server.reset(new WebServer(port));
   Serial.printf("[%lu] [WEB] [MEM] Free heap after WebServer allocation: %d bytes\n", millis(), ESP.getFreeHeap());
 
   if (!server) {
@@ -82,33 +59,38 @@ void CrossPointWebServer::begin() {
 
   // Setup routes
   Serial.printf("[%lu] [WEB] Setting up routes...\n", millis());
-  server->on("/", HTTP_GET, [this]() { handleRoot(); });
-  server->on("/status", HTTP_GET, [this]() { handleStatus(); });
-  server->on("/files", HTTP_GET, [this]() { handleFileList(); });
+  server->on("/", HTTP_GET, [this] { handleRoot(); });
+  server->on("/files", HTTP_GET, [this] { handleFileList(); });
+
+  server->on("/api/status", HTTP_GET, [this] { handleStatus(); });
+  server->on("/api/files", HTTP_GET, [this] { handleFileListData(); });
 
   // Upload endpoint with special handling for multipart form data
-  server->on("/upload", HTTP_POST, [this]() { handleUploadPost(); }, [this]() { handleUpload(); });
+  server->on("/upload", HTTP_POST, [this] { handleUploadPost(); }, [this] { handleUpload(); });
 
   // Create folder endpoint
-  server->on("/mkdir", HTTP_POST, [this]() { handleCreateFolder(); });
+  server->on("/mkdir", HTTP_POST, [this] { handleCreateFolder(); });
 
   // Delete file/folder endpoint
-  server->on("/delete", HTTP_POST, [this]() { handleDelete(); });
+  server->on("/delete", HTTP_POST, [this] { handleDelete(); });
 
-  server->onNotFound([this]() { handleNotFound(); });
+  server->onNotFound([this] { handleNotFound(); });
   Serial.printf("[%lu] [WEB] [MEM] Free heap after route setup: %d bytes\n", millis(), ESP.getFreeHeap());
 
   server->begin();
   running = true;
 
   Serial.printf("[%lu] [WEB] Web server started on port %d\n", millis(), port);
-  Serial.printf("[%lu] [WEB] Access at http://%s/\n", millis(), WiFi.localIP().toString().c_str());
+  // Show the correct IP based on network mode
+  const String ipAddr = apMode ? WiFi.softAPIP().toString() : WiFi.localIP().toString();
+  Serial.printf("[%lu] [WEB] Access at http://%s/\n", millis(), ipAddr.c_str());
   Serial.printf("[%lu] [WEB] [MEM] Free heap after server.begin(): %d bytes\n", millis(), ESP.getFreeHeap());
 }
 
 void CrossPointWebServer::stop() {
   if (!running || !server) {
-    Serial.printf("[%lu] [WEB] stop() called but already stopped (running=%d, server=%p)\n", millis(), running, server);
+    Serial.printf("[%lu] [WEB] stop() called but already stopped (running=%d, server=%p)\n", millis(), running,
+                  server.get());
     return;
   }
 
@@ -128,9 +110,7 @@ void CrossPointWebServer::stop() {
   delay(50);
   Serial.printf("[%lu] [WEB] Waited 50ms before deleting server\n", millis());
 
-  delete server;
-  server = nullptr;
-
+  server.reset();
   Serial.printf("[%lu] [WEB] Web server stopped and deleted\n", millis());
   Serial.printf("[%lu] [WEB] [MEM] Free heap after delete server: %d bytes\n", millis(), ESP.getFreeHeap());
 
@@ -139,7 +119,7 @@ void CrossPointWebServer::stop() {
   Serial.printf("[%lu] [WEB] [MEM] Free heap final: %d bytes\n", millis(), ESP.getFreeHeap());
 }
 
-void CrossPointWebServer::handleClient() {
+void CrossPointWebServer::handleClient() const {
   static unsigned long lastDebugPrint = 0;
 
   // Check running flag FIRST before accessing server
@@ -162,29 +142,26 @@ void CrossPointWebServer::handleClient() {
   server->handleClient();
 }
 
-void CrossPointWebServer::handleRoot() {
-  String html = HomePageHtml;
-
-  // Replace placeholders with actual values
-  html.replace("%VERSION%", CROSSPOINT_VERSION);
-  html.replace("%IP_ADDRESS%", WiFi.localIP().toString());
-  html.replace("%FREE_HEAP%", String(ESP.getFreeHeap()));
-
-  server->send(200, "text/html", html);
+void CrossPointWebServer::handleRoot() const {
+  server->send(200, "text/html", HomePageHtml);
   Serial.printf("[%lu] [WEB] Served root page\n", millis());
 }
 
-void CrossPointWebServer::handleNotFound() {
+void CrossPointWebServer::handleNotFound() const {
   String message = "404 Not Found\n\n";
   message += "URI: " + server->uri() + "\n";
   server->send(404, "text/plain", message);
 }
 
-void CrossPointWebServer::handleStatus() {
+void CrossPointWebServer::handleStatus() const {
+  // Get correct IP based on AP vs STA mode
+  const String ipAddr = apMode ? WiFi.softAPIP().toString() : WiFi.localIP().toString();
+
   String json = "{";
   json += "\"version\":\"" + String(CROSSPOINT_VERSION) + "\",";
-  json += "\"ip\":\"" + WiFi.localIP().toString() + "\",";
-  json += "\"rssi\":" + String(WiFi.RSSI()) + ",";
+  json += "\"ip\":\"" + ipAddr + "\",";
+  json += "\"mode\":\"" + String(apMode ? "AP" : "STA") + "\",";
+  json += "\"rssi\":" + String(apMode ? 0 : WiFi.RSSI()) + ",";  // RSSI not applicable in AP mode
   json += "\"freeHeap\":" + String(ESP.getFreeHeap()) + ",";
   json += "\"uptime\":" + String(millis() / 1000);
   json += "}";
@@ -192,26 +169,24 @@ void CrossPointWebServer::handleStatus() {
   server->send(200, "application/json", json);
 }
 
-std::vector<FileInfo> CrossPointWebServer::scanFiles(const char* path) {
-  std::vector<FileInfo> files;
-
+void CrossPointWebServer::scanFiles(const char* path, const std::function<void(FileInfo)>& callback) const {
   File root = SD.open(path);
   if (!root) {
     Serial.printf("[%lu] [WEB] Failed to open directory: %s\n", millis(), path);
-    return files;
+    return;
   }
 
   if (!root.isDirectory()) {
     Serial.printf("[%lu] [WEB] Not a directory: %s\n", millis(), path);
     root.close();
-    return files;
+    return;
   }
 
   Serial.printf("[%lu] [WEB] Scanning files in: %s\n", millis(), path);
 
   File file = root.openNextFile();
   while (file) {
-    String fileName = String(file.name());
+    auto fileName = String(file.name());
 
     // Skip hidden items (starting with ".")
     bool shouldHide = fileName.startsWith(".");
@@ -239,37 +214,24 @@ std::vector<FileInfo> CrossPointWebServer::scanFiles(const char* path) {
         info.isEpub = isEpubFile(info.name);
       }
 
-      files.push_back(info);
+      callback(info);
     }
 
     file.close();
     file = root.openNextFile();
   }
   root.close();
-
-  Serial.printf("[%lu] [WEB] Found %d items (files and folders)\n", millis(), files.size());
-  return files;
 }
 
-String CrossPointWebServer::formatFileSize(size_t bytes) {
-  if (bytes < 1024) {
-    return String(bytes) + " B";
-  } else if (bytes < 1024 * 1024) {
-    return String(bytes / 1024.0, 1) + " KB";
-  } else {
-    return String(bytes / (1024.0 * 1024.0), 1) + " MB";
-  }
-}
-
-bool CrossPointWebServer::isEpubFile(const String& filename) {
+bool CrossPointWebServer::isEpubFile(const String& filename) const {
   String lower = filename;
   lower.toLowerCase();
   return lower.endsWith(".epub");
 }
 
-void CrossPointWebServer::handleFileList() {
-  String html = FilesPageHeaderHtml;
+void CrossPointWebServer::handleFileList() const { server->send(200, "text/html", FilesPageHtml); }
 
+void CrossPointWebServer::handleFileListData() const {
   // Get current path from query string (default to root)
   String currentPath = "/";
   if (server->hasArg("path")) {
@@ -284,180 +246,35 @@ void CrossPointWebServer::handleFileList() {
     }
   }
 
-  // Get message from query string if present
-  if (server->hasArg("msg")) {
-    String msg = escapeHtml(server->arg("msg"));
-    String msgType = server->hasArg("type") ? escapeHtml(server->arg("type")) : "success";
-    html += "<div class=\"message " + msgType + "\">" + msg + "</div>";
+  server->setContentLength(CONTENT_LENGTH_UNKNOWN);
+  server->send(200, "application/json", "");
+  server->sendContent("[");
+  char output[512];
+  constexpr size_t outputSize = sizeof(output);
+  bool seenFirst = false;
+  scanFiles(currentPath.c_str(), [this, &output, seenFirst](const FileInfo& info) mutable {
+    JsonDocument doc;
+    doc["name"] = info.name;
+    doc["size"] = info.size;
+    doc["isDirectory"] = info.isDirectory;
+    doc["isEpub"] = info.isEpub;
+    const size_t written = serializeJson(doc, output, outputSize);
+    if (written >= outputSize) {
+      // JSON output truncated; skip this entry to avoid sending malformed JSON
+      Serial.printf("[%lu] [WEB] Skipping file entry with oversized JSON for name: %s\n", millis(), info.name.c_str());
+      return;
     }
 
-  // Hidden input to store current path for JavaScript
-  html += "<input type=\"hidden\" id=\"currentPath\" value=\"" + currentPath + "\">";
-
-  // Scan files in current path first (we need counts for the header)
-  std::vector<FileInfo> files = scanFiles(currentPath.c_str());
-
-  // Count items
-  int epubCount = 0;
-  int folderCount = 0;
-  size_t totalSize = 0;
-  for (const auto& file : files) {
-    if (file.isDirectory) {
-      folderCount++;
+    if (seenFirst) {
+      server->sendContent(",");
     } else {
-      if (file.isEpub) epubCount++;
-      totalSize += file.size;
+      seenFirst = true;
     }
-  }
-
-  // Page header with inline breadcrumb and action buttons
-  html += "<div class=\"page-header\">";
-  html += "<div class=\"page-header-left\">";
-  html += "<h1>📁 File Manager</h1>";
-
-  // Inline breadcrumb
-  html += "<div class=\"breadcrumb-inline\">";
-  html += "<span class=\"sep\">/</span>";
-
-  if (currentPath == "/") {
-    html += "<span class=\"current\">🏠</span>";
-  } else {
-    html += "<a href=\"/files\">🏠</a>";
-    String pathParts = currentPath.substring(1);  // Remove leading /
-    String buildPath = "";
-    int start = 0;
-    int end = pathParts.indexOf('/');
-
-    while (start < (int)pathParts.length()) {
-      String part;
-      if (end == -1) {
-        part = pathParts.substring(start);
-        buildPath += "/" + part;
-        html += "<span class=\"sep\">/</span><span class=\"current\">" + escapeHtml(part) + "</span>";
-        break;
-      } else {
-        part = pathParts.substring(start, end);
-        buildPath += "/" + part;
-        html += "<span class=\"sep\">/</span><a href=\"/files?path=" + buildPath + "\">" + escapeHtml(part) + "</a>";
-        start = end + 1;
-        end = pathParts.indexOf('/', start);
-      }
-    }
-  }
-  html += "</div>";
-  html += "</div>";
-
-  // Action buttons
-  html += "<div class=\"action-buttons\">";
-  html += "<button class=\"action-btn upload-action-btn\" onclick=\"openUploadModal()\">";
-  html += "📤 Upload";
-  html += "</button>";
-  html += "<button class=\"action-btn folder-action-btn\" onclick=\"openFolderModal()\">";
-  html += "📁 New Folder";
-  html += "</button>";
-  html += "</div>";
-
-  html += "</div>";  // end page-header
-
-  // Contents card with inline summary
-  html += "<div class=\"card\">";
-
-  // Contents header with inline stats
-  html += "<div class=\"contents-header\">";
-  html += "<h2 class=\"contents-title\">Contents</h2>";
-  html += "<span class=\"summary-inline\">";
-  html += String(folderCount) + " folder" + (folderCount != 1 ? "s" : "") + ", ";
-  html += String(files.size() - folderCount) + " file" + ((files.size() - folderCount) != 1 ? "s" : "") + ", ";
-  html += formatFileSize(totalSize);
-  html += "</span>";
-  html += "</div>";
-
-  if (files.empty()) {
-    html += "<div class=\"no-files\">This folder is empty</div>";
-  } else {
-    html += "<table class=\"file-table\">";
-    html += "<tr><th>Name</th><th>Type</th><th>Size</th><th class=\"actions-col\">Actions</th></tr>";
-
-    // Sort files: folders first, then epub files, then other files, alphabetically within each group
-    std::sort(files.begin(), files.end(), [](const FileInfo& a, const FileInfo& b) {
-      // Folders come first
-      if (a.isDirectory != b.isDirectory) return a.isDirectory > b.isDirectory;
-      // Then sort by epub status (epubs first among files)
-      if (a.isEpub != b.isEpub) return a.isEpub > b.isEpub;
-      // Then alphabetically
-      return a.name < b.name;
+    server->sendContent(output);
   });
-
-    for (const auto& file : files) {
-      String rowClass;
-      String icon;
-      String badge;
-      String typeStr;
-      String sizeStr;
-
-      if (file.isDirectory) {
-        rowClass = "folder-row";
-        icon = "📁";
-        badge = "<span class=\"folder-badge\">FOLDER</span>";
-        typeStr = "Folder";
-        sizeStr = "-";
-
-        // Build the path to this folder
-        String folderPath = currentPath;
-        if (!folderPath.endsWith("/")) folderPath += "/";
-        folderPath += file.name;
-
-        html += "<tr class=\"" + rowClass + "\">";
-        html += "<td><span class=\"file-icon\">" + icon + "</span>";
-        html += "<a href=\"/files?path=" + folderPath + "\" class=\"folder-link\">" + escapeHtml(file.name) + "</a>" +
-                badge + "</td>";
-        html += "<td>" + typeStr + "</td>";
-        html += "<td>" + sizeStr + "</td>";
-        // Escape quotes for JavaScript string
-        String escapedName = file.name;
-        escapedName.replace("'", "\\'");
-        String escapedPath = folderPath;
-        escapedPath.replace("'", "\\'");
-        html += "<td class=\"actions-col\"><button class=\"delete-btn\" onclick=\"openDeleteModal('" + escapedName +
-                "', '" + escapedPath + "', true)\" title=\"Delete folder\">🗑️</button></td>";
-        html += "</tr>";
-      } else {
-        rowClass = file.isEpub ? "epub-file" : "";
-        icon = file.isEpub ? "📗" : "📄";
-        badge = file.isEpub ? "<span class=\"epub-badge\">EPUB</span>" : "";
-        String ext = file.name.substring(file.name.lastIndexOf('.') + 1);
-        ext.toUpperCase();
-        typeStr = ext;
-        sizeStr = formatFileSize(file.size);
-
-        // Build file path for delete
-        String filePath = currentPath;
-        if (!filePath.endsWith("/")) filePath += "/";
-        filePath += file.name;
-
-        html += "<tr class=\"" + rowClass + "\">";
-        html += "<td><span class=\"file-icon\">" + icon + "</span>" + escapeHtml(file.name) + badge + "</td>";
-        html += "<td>" + typeStr + "</td>";
-        html += "<td>" + sizeStr + "</td>";
-        // Escape quotes for JavaScript string
-        String escapedName = file.name;
-        escapedName.replace("'", "\\'");
-        String escapedPath = filePath;
-        escapedPath.replace("'", "\\'");
-        html += "<td class=\"actions-col\"><button class=\"delete-btn\" onclick=\"openDeleteModal('" + escapedName +
-                "', '" + escapedPath + "', false)\" title=\"Delete file\">🗑️</button></td>";
-        html += "</tr>";
-      }
-    }
-
-    html += "</table>";
-  }
-
-  html += "</div>";
-
-  html += FilesPageFooterHtml;
-
-  server->send(200, "text/html", html);
+  server->sendContent("]");
+  // End of streamed response, empty chunk to signal client
+  server->sendContent("");
   Serial.printf("[%lu] [WEB] Served file listing page for path: %s\n", millis(), currentPath.c_str());
 }
 
@@ -469,7 +286,7 @@ static size_t uploadSize = 0;
 static bool uploadSuccess = false;
 static String uploadError = "";
 
-void CrossPointWebServer::handleUpload() {
+void CrossPointWebServer::handleUpload() const {
   static unsigned long lastWriteTime = 0;
   static unsigned long uploadStartTime = 0;
   static size_t lastLoggedSize = 0;
@@ -480,7 +297,7 @@ void CrossPointWebServer::handleUpload() {
     return;
   }
 
-  HTTPUpload& upload = server->upload();
+  const HTTPUpload& upload = server->upload();
 
   if (upload.status == UPLOAD_FILE_START) {
     uploadFileName = upload.filename;
@@ -523,8 +340,7 @@ void CrossPointWebServer::handleUpload() {
     }
 
     // Open file for writing
-    uploadFile = SD.open(filePath.c_str(), FILE_WRITE);
-    if (!uploadFile) {
+    if (!FsHelpers::openFileForWrite("WEB", filePath, uploadFile)) {
       uploadError = "Failed to create file on SD card";
       Serial.printf("[%lu] [WEB] [UPLOAD] FAILED to create file: %s\n", millis(), filePath.c_str());
       return;
@@ -533,10 +349,10 @@ void CrossPointWebServer::handleUpload() {
     Serial.printf("[%lu] [WEB] [UPLOAD] File created successfully: %s\n", millis(), filePath.c_str());
   } else if (upload.status == UPLOAD_FILE_WRITE) {
     if (uploadFile && uploadError.isEmpty()) {
-      unsigned long writeStartTime = millis();
-      size_t written = uploadFile.write(upload.buf, upload.currentSize);
-      unsigned long writeEndTime = millis();
-      unsigned long writeDuration = writeEndTime - writeStartTime;
+      const unsigned long writeStartTime = millis();
+      const size_t written = uploadFile.write(upload.buf, upload.currentSize);
+      const unsigned long writeEndTime = millis();
+      const unsigned long writeDuration = writeEndTime - writeStartTime;
 
       if (written != upload.currentSize) {
         uploadError = "Failed to write to SD card - disk may be full";
@@ -548,9 +364,9 @@ void CrossPointWebServer::handleUpload() {
 
         // Log progress every 50KB or if write took >100ms
         if (uploadSize - lastLoggedSize >= 51200 || writeDuration > 100) {
-          unsigned long timeSinceStart = millis() - uploadStartTime;
-          unsigned long timeSinceLastWrite = millis() - lastWriteTime;
-          float kbps = (uploadSize / 1024.0) / (timeSinceStart / 1000.0);
+          const unsigned long timeSinceStart = millis() - uploadStartTime;
+          const unsigned long timeSinceLastWrite = millis() - lastWriteTime;
+          const float kbps = (uploadSize / 1024.0) / (timeSinceStart / 1000.0);
 
           Serial.printf(
               "[%lu] [WEB] [UPLOAD] Progress: %d bytes (%.1f KB), %.1f KB/s, write took %lu ms, gap since last: %lu "
@@ -584,23 +400,23 @@ void CrossPointWebServer::handleUpload() {
   }
 }
 
-void CrossPointWebServer::handleUploadPost() {
+void CrossPointWebServer::handleUploadPost() const {
   if (uploadSuccess) {
     server->send(200, "text/plain", "File uploaded successfully: " + uploadFileName);
   } else {
-    String error = uploadError.isEmpty() ? "Unknown error during upload" : uploadError;
+    const String error = uploadError.isEmpty() ? "Unknown error during upload" : uploadError;
     server->send(400, "text/plain", error);
   }
 }
 
-void CrossPointWebServer::handleCreateFolder() {
+void CrossPointWebServer::handleCreateFolder() const {
   // Get folder name from form data
   if (!server->hasArg("name")) {
     server->send(400, "text/plain", "Missing folder name");
     return;
   }
 
-  String folderName = server->arg("name");
+  const String folderName = server->arg("name");
 
   // Validate folder name
   if (folderName.isEmpty()) {
@@ -643,7 +459,7 @@ void CrossPointWebServer::handleCreateFolder() {
   }
 }
 
-void CrossPointWebServer::handleDelete() {
+void CrossPointWebServer::handleDelete() const {
   // Get path from form data
   if (!server->hasArg("path")) {
     server->send(400, "text/plain", "Missing path");
@@ -651,7 +467,7 @@ void CrossPointWebServer::handleDelete() {
   }
 
   String itemPath = server->arg("path");
-  String itemType = server->hasArg("type") ? server->arg("type") : "file";
+  const String itemType = server->hasArg("type") ? server->arg("type") : "file";
 
   // Validate path
   if (itemPath.isEmpty() || itemPath == "/") {
@@ -665,7 +481,7 @@ void CrossPointWebServer::handleDelete() {
   }
 
   // Security check: prevent deletion of protected items
-  String itemName = itemPath.substring(itemPath.lastIndexOf('/') + 1);
+  const String itemName = itemPath.substring(itemPath.lastIndexOf('/') + 1);
 
   // Check if item starts with a dot (hidden/system file)
   if (itemName.startsWith(".")) {

src/network/CrossPointWebServer.h

@@ -2,8 +2,6 @@
 
 #include <WebServer.h>
 
-#include <functional>
-#include <string>
 #include <vector>
 
 // Structure to hold file information
@@ -26,7 +24,7 @@ class CrossPointWebServer {
   void stop();
 
   // Call this periodically to handle client requests
-  void handleClient();
+  void handleClient() const;
 
   // Check if server is running
   bool isRunning() const { return running; }
@@ -35,22 +33,24 @@ class CrossPointWebServer {
   uint16_t getPort() const { return port; }
 
  private:
-  WebServer* server = nullptr;
+  std::unique_ptr<WebServer> server = nullptr;
   bool running = false;
+  bool apMode = false;  // true when running in AP mode, false for STA mode
   uint16_t port = 80;
 
   // File scanning
-  std::vector<FileInfo> scanFiles(const char* path = "/");
-  String formatFileSize(size_t bytes);
-  bool isEpubFile(const String& filename);
+  void scanFiles(const char* path, const std::function<void(FileInfo)>& callback) const;
+  String formatFileSize(size_t bytes) const;
+  bool isEpubFile(const String& filename) const;
 
   // Request handlers
-  void handleRoot();
-  void handleNotFound();
-  void handleStatus();
-  void handleFileList();
-  void handleUpload();
-  void handleUploadPost();
-  void handleCreateFolder();
-  void handleDelete();
+  void handleRoot() const;
+  void handleNotFound() const;
+  void handleStatus() const;
+  void handleFileList() const;
+  void handleFileListData() const;
+  void handleUpload() const;
+  void handleUploadPost() const;
+  void handleCreateFolder() const;
+  void handleDelete() const;
 };

src/network/OtaUpdater.cpp

@@ -0,0 +1,169 @@
+#include "OtaUpdater.h"
+
+#include <ArduinoJson.h>
+#include <HTTPClient.h>
+#include <Update.h>
+#include <WiFiClientSecure.h>
+
+namespace {
+constexpr char latestReleaseUrl[] = "https://api.github.com/repos/daveallie/crosspoint-reader/releases/latest";
+}
+
+OtaUpdater::OtaUpdaterError OtaUpdater::checkForUpdate() {
+  const std::unique_ptr<WiFiClientSecure> client(new WiFiClientSecure);
+  client->setInsecure();
+  HTTPClient http;
+
+  Serial.printf("[%lu] [OTA] Fetching: %s\n", millis(), latestReleaseUrl);
+
+  http.begin(*client, latestReleaseUrl);
+  http.addHeader("User-Agent", "CrossPoint-ESP32-" CROSSPOINT_VERSION);
+
+  const int httpCode = http.GET();
+  if (httpCode != HTTP_CODE_OK) {
+    Serial.printf("[%lu] [OTA] HTTP error: %d\n", millis(), httpCode);
+    http.end();
+    return HTTP_ERROR;
+  }
+
+  JsonDocument doc;
+  const DeserializationError error = deserializeJson(doc, *client);
+  http.end();
+  if (error) {
+    Serial.printf("[%lu] [OTA] JSON parse failed: %s\n", millis(), error.c_str());
+    return JSON_PARSE_ERROR;
+  }
+
+  if (!doc["tag_name"].is<std::string>()) {
+    Serial.printf("[%lu] [OTA] No tag_name found\n", millis());
+    return JSON_PARSE_ERROR;
+  }
+  if (!doc["assets"].is<JsonArray>()) {
+    Serial.printf("[%lu] [OTA] No assets found\n", millis());
+    return JSON_PARSE_ERROR;
+  }
+
+  latestVersion = doc["tag_name"].as<std::string>();
+
+  for (int i = 0; i < doc["assets"].size(); i++) {
+    if (doc["assets"][i]["name"] == "firmware.bin") {
+      otaUrl = doc["assets"][i]["browser_download_url"].as<std::string>();
+      otaSize = doc["assets"][i]["size"].as<size_t>();
+      totalSize = otaSize;
+      updateAvailable = true;
+      break;
+    }
+  }
+
+  if (!updateAvailable) {
+    Serial.printf("[%lu] [OTA] No firmware.bin asset found\n", millis());
+    return NO_UPDATE;
+  }
+
+  Serial.printf("[%lu] [OTA] Found update: %s\n", millis(), latestVersion.c_str());
+  return OK;
+}
+
+bool OtaUpdater::isUpdateNewer() {
+  if (!updateAvailable || latestVersion.empty() || latestVersion == CROSSPOINT_VERSION) {
+    return false;
+  }
+
+  // semantic version check (only match on 3 segments)
+  const auto updateMajor = stoi(latestVersion.substr(0, latestVersion.find('.')));
+  const auto updateMinor = stoi(
+      latestVersion.substr(latestVersion.find('.') + 1, latestVersion.find_last_of('.') - latestVersion.find('.') - 1));
+  const auto updatePatch = stoi(latestVersion.substr(latestVersion.find_last_of('.') + 1));
+
+  std::string currentVersion = CROSSPOINT_VERSION;
+  const auto currentMajor = stoi(currentVersion.substr(0, currentVersion.find('.')));
+  const auto currentMinor = stoi(currentVersion.substr(
+      currentVersion.find('.') + 1, currentVersion.find_last_of('.') - currentVersion.find('.') - 1));
+  const auto currentPatch = stoi(currentVersion.substr(currentVersion.find_last_of('.') + 1));
+
+  if (updateMajor > currentMajor) {
+    return true;
+  }
+  if (updateMajor < currentMajor) {
+    return false;
+  }
+
+  if (updateMinor > currentMinor) {
+    return true;
+  }
+  if (updateMinor < currentMinor) {
+    return false;
+  }
+
+  if (updatePatch > currentPatch) {
+    return true;
+  }
+  return false;
+}
+
+const std::string& OtaUpdater::getLatestVersion() { return latestVersion; }
+
+OtaUpdater::OtaUpdaterError OtaUpdater::installUpdate(const std::function<void(size_t, size_t)>& onProgress) {
+  if (!isUpdateNewer()) {
+    return UPDATE_OLDER_ERROR;
+  }
+
+  const std::unique_ptr<WiFiClientSecure> client(new WiFiClientSecure);
+  client->setInsecure();
+  HTTPClient http;
+
+  Serial.printf("[%lu] [OTA] Fetching: %s\n", millis(), otaUrl.c_str());
+
+  http.begin(*client, otaUrl.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] [OTA] Download failed: %d\n", millis(), httpCode);
+    http.end();
+    return HTTP_ERROR;
+  }
+
+  // 2. Get length and stream
+  const size_t contentLength = http.getSize();
+
+  if (contentLength != otaSize) {
+    Serial.printf("[%lu] [OTA] Invalid content length\n", millis());
+    http.end();
+    return HTTP_ERROR;
+  }
+
+  // 3. Begin the ESP-IDF Update process
+  if (!Update.begin(otaSize)) {
+    Serial.printf("[%lu] [OTA] Not enough space. Error: %s\n", millis(), Update.errorString());
+    http.end();
+    return INTERNAL_UPDATE_ERROR;
+  }
+
+  this->totalSize = otaSize;
+  Serial.printf("[%lu] [OTA] Update started\n", millis());
+  Update.onProgress([this, onProgress](const size_t progress, const size_t total) {
+    this->processedSize = progress;
+    this->totalSize = total;
+    onProgress(progress, total);
+  });
+  const size_t written = Update.writeStream(*client);
+  http.end();
+
+  if (written == otaSize) {
+    Serial.printf("[%lu] [OTA] Successfully written %u bytes\n", millis(), written);
+  } else {
+    Serial.printf("[%lu] [OTA] Written only %u/%u bytes. Error: %s\n", millis(), written, otaSize,
+                  Update.errorString());
+    return INTERNAL_UPDATE_ERROR;
+  }
+
+  if (Update.end() && Update.isFinished()) {
+    Serial.printf("[%lu] [OTA] Update complete\n", millis());
+    return OK;
+  } else {
+    Serial.printf("[%lu] [OTA] Error Occurred: %s\n", millis(), Update.errorString());
+    return INTERNAL_UPDATE_ERROR;
+  }
+}

src/network/OtaUpdater.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <functional>
+#include <string>
+
+class OtaUpdater {
+  bool updateAvailable = false;
+  std::string latestVersion;
+  std::string otaUrl;
+  size_t otaSize = 0;
+
+ public:
+  enum OtaUpdaterError {
+    OK = 0,
+    NO_UPDATE,
+    HTTP_ERROR,
+    JSON_PARSE_ERROR,
+    UPDATE_OLDER_ERROR,
+    INTERNAL_UPDATE_ERROR,
+    OOM_ERROR,
+  };
+  size_t processedSize = 0;
+  size_t totalSize = 0;
+
+  OtaUpdater() = default;
+  bool isUpdateNewer();
+  const std::string& getLatestVersion();
+  OtaUpdaterError checkForUpdate();
+  OtaUpdaterError installUpdate(const std::function<void(size_t, size_t)>& onProgress);
+};

src/network/html/FilesPage.html

@@ -0,0 +1,859 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="UTF-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <title>CrossPoint Reader - Files</title>
+  <style>
+    body {
+      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
+      Oxygen, Ubuntu, sans-serif;
+      max-width: 800px;
+      margin: 0 auto;
+      padding: 20px;
+      background-color: #f5f5f5;
+      color: #333;
+    }
+    h1 {
+      color: #2c3e50;
+      margin-bottom: 5px;
+    }
+    h2 {
+      color: #34495e;
+      margin-top: 0;
+    }
+    .card {
+      background: white;
+      border-radius: 8px;
+      padding: 20px;
+      margin: 15px 0;
+      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+    }
+    .page-header {
+      display: flex;
+      justify-content: space-between;
+      align-items: center;
+      flex-wrap: wrap;
+      gap: 15px;
+      margin-bottom: 20px;
+      padding-bottom: 15px;
+      border-bottom: 2px solid #3498db;
+    }
+    .page-header-left {
+      display: flex;
+      align-items: baseline;
+      gap: 12px;
+      flex-wrap: wrap;
+    }
+    .breadcrumb-inline {
+      color: #7f8c8d;
+      font-size: 1.1em;
+    }
+    .breadcrumb-inline a {
+      color: #3498db;
+      text-decoration: none;
+    }
+    .breadcrumb-inline a:hover {
+      text-decoration: underline;
+    }
+    .breadcrumb-inline .sep {
+      margin: 0 6px;
+      color: #bdc3c7;
+    }
+    .breadcrumb-inline .current {
+      color: #2c3e50;
+      font-weight: 500;
+    }
+    .nav-links {
+      margin: 20px 0;
+    }
+    .nav-links a {
+      display: inline-block;
+      padding: 10px 20px;
+      background-color: #3498db;
+      color: white;
+      text-decoration: none;
+      border-radius: 4px;
+      margin-right: 10px;
+    }
+    .nav-links a:hover {
+      background-color: #2980b9;
+    }
+    /* Action buttons */
+    .action-buttons {
+      display: flex;
+      gap: 10px;
+    }
+    .action-btn {
+      color: white;
+      padding: 10px 16px;
+      border: none;
+      border-radius: 4px;
+      cursor: pointer;
+      font-size: 0.95em;
+      font-weight: 600;
+      display: flex;
+      align-items: center;
+      gap: 6px;
+    }
+    .upload-action-btn {
+      background-color: #27ae60;
+    }
+    .upload-action-btn:hover {
+      background-color: #219a52;
+    }
+    .folder-action-btn {
+      background-color: #f39c12;
+    }
+    .folder-action-btn:hover {
+      background-color: #d68910;
+    }
+    /* Upload modal */
+    .modal-overlay {
+      display: none;
+      position: fixed;
+      top: 0;
+      left: 0;
+      right: 0;
+      bottom: 0;
+      background: rgba(0, 0, 0, 0.5);
+      z-index: 200;
+      justify-content: center;
+      align-items: center;
+    }
+    .modal-overlay.open {
+      display: flex;
+    }
+    .modal {
+      background: white;
+      border-radius: 8px;
+      padding: 25px;
+      max-width: 450px;
+      width: 90%;
+      box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
+    }
+    .modal h3 {
+      margin: 0 0 15px 0;
+      color: #2c3e50;
+    }
+    .modal-close {
+      float: right;
+      background: none;
+      border: none;
+      font-size: 1.5em;
+      cursor: pointer;
+      color: #7f8c8d;
+      line-height: 1;
+    }
+    .modal-close:hover {
+      color: #2c3e50;
+    }
+    .file-table {
+      width: 100%;
+      border-collapse: collapse;
+    }
+    .file-table th,
+    .file-table td {
+      padding: 12px;
+      text-align: left;
+      border-bottom: 1px solid #eee;
+    }
+    .file-table th {
+      background-color: #f8f9fa;
+      font-weight: 600;
+      color: #7f8c8d;
+    }
+    .file-table tr:hover {
+      background-color: #f8f9fa;
+    }
+    .epub-file {
+      background-color: #e8f6e9 !important;
+    }
+    .epub-file:hover {
+      background-color: #d4edda !important;
+    }
+    .folder-row {
+      background-color: #fff9e6 !important;
+    }
+    .folder-row:hover {
+      background-color: #fff3cd !important;
+    }
+    .epub-badge {
+      display: inline-block;
+      padding: 2px 8px;
+      background-color: #27ae60;
+      color: white;
+      border-radius: 10px;
+      font-size: 0.75em;
+      margin-left: 8px;
+    }
+    .folder-badge {
+      display: inline-block;
+      padding: 2px 8px;
+      background-color: #f39c12;
+      color: white;
+      border-radius: 10px;
+      font-size: 0.75em;
+      margin-left: 8px;
+    }
+    .file-icon {
+      margin-right: 8px;
+    }
+    .folder-link {
+      color: #2c3e50;
+      text-decoration: none;
+      cursor: pointer;
+    }
+    .folder-link:hover {
+      color: #3498db;
+      text-decoration: underline;
+    }
+    .upload-form {
+      margin-top: 10px;
+    }
+    .upload-form input[type="file"] {
+      margin: 10px 0;
+      width: 100%;
+    }
+    .upload-btn {
+      background-color: #27ae60;
+      color: white;
+      padding: 10px 20px;
+      border: none;
+      border-radius: 4px;
+      cursor: pointer;
+      font-size: 1em;
+      width: 100%;
+    }
+    .upload-btn:hover {
+      background-color: #219a52;
+    }
+    .upload-btn:disabled {
+      background-color: #95a5a6;
+      cursor: not-allowed;
+    }
+    .file-info {
+      color: #7f8c8d;
+      font-size: 0.85em;
+      margin: 8px 0;
+    }
+    .no-files {
+      text-align: center;
+      color: #95a5a6;
+      padding: 40px;
+      font-style: italic;
+    }
+    .message {
+      padding: 15px;
+      border-radius: 4px;
+      margin: 15px 0;
+    }
+    .message.success {
+      background-color: #d4edda;
+      color: #155724;
+      border: 1px solid #c3e6cb;
+    }
+    .message.error {
+      background-color: #f8d7da;
+      color: #721c24;
+      border: 1px solid #f5c6cb;
+    }
+    .contents-header {
+      display: flex;
+      justify-content: space-between;
+      align-items: center;
+      margin-bottom: 12px;
+    }
+    .contents-title {
+      font-size: 1.1em;
+      font-weight: 600;
+      color: #34495e;
+      margin: 0;
+    }
+    .summary-inline {
+      color: #7f8c8d;
+      font-size: 0.9em;
+    }
+    #progress-container {
+      display: none;
+      margin-top: 10px;
+    }
+    #progress-bar {
+      width: 100%;
+      height: 20px;
+      background-color: #e0e0e0;
+      border-radius: 10px;
+      overflow: hidden;
+    }
+    #progress-fill {
+      height: 100%;
+      background-color: #27ae60;
+      width: 0%;
+      transition: width 0.3s;
+    }
+    #progress-text {
+      text-align: center;
+      margin-top: 5px;
+      font-size: 0.9em;
+      color: #7f8c8d;
+    }
+    .folder-form {
+      margin-top: 10px;
+    }
+    .folder-input {
+      width: 100%;
+      padding: 10px;
+      border: 1px solid #ddd;
+      border-radius: 4px;
+      font-size: 1em;
+      margin-bottom: 10px;
+      box-sizing: border-box;
+    }
+    .folder-btn {
+      background-color: #f39c12;
+      color: white;
+      padding: 10px 20px;
+      border: none;
+      border-radius: 4px;
+      cursor: pointer;
+      font-size: 1em;
+      width: 100%;
+    }
+    .folder-btn:hover {
+      background-color: #d68910;
+    }
+    /* Delete button styles */
+    .delete-btn {
+      background: none;
+      border: none;
+      cursor: pointer;
+      font-size: 1.1em;
+      padding: 4px 8px;
+      border-radius: 4px;
+      color: #95a5a6;
+      transition: all 0.15s;
+    }
+    .delete-btn:hover {
+      background-color: #fee;
+      color: #e74c3c;
+    }
+    .actions-col {
+      width: 60px;
+      text-align: center;
+    }
+    /* Delete modal */
+    .delete-warning {
+      color: #e74c3c;
+      font-weight: 600;
+      margin: 10px 0;
+    }
+    .delete-item-name {
+      font-weight: 600;
+      color: #2c3e50;
+      word-break: break-all;
+    }
+    .delete-btn-confirm {
+      background-color: #e74c3c;
+      color: white;
+      padding: 10px 20px;
+      border: none;
+      border-radius: 4px;
+      cursor: pointer;
+      font-size: 1em;
+      width: 100%;
+    }
+    .delete-btn-confirm:hover {
+      background-color: #c0392b;
+    }
+    .delete-btn-cancel {
+      background-color: #95a5a6;
+      color: white;
+      padding: 10px 20px;
+      border: none;
+      border-radius: 4px;
+      cursor: pointer;
+      font-size: 1em;
+      width: 100%;
+      margin-top: 10px;
+    }
+    .delete-btn-cancel:hover {
+      background-color: #7f8c8d;
+    }
+    .loader-container {
+      display: flex;
+      justify-content: center;
+      align-items: center;
+      margin: 20px 0;
+    }
+    .loader {
+      width: 48px;
+      height: 48px;
+      border: 5px solid #AAA;
+      border-bottom-color: transparent;
+      border-radius: 50%;
+      display: inline-block;
+      box-sizing: border-box;
+      animation: rotation 1s linear infinite;
+    }
+    @keyframes rotation {
+      from {
+        transform: rotate(0deg);
+      }
+      to {
+        transform: rotate(360deg);
+      }
+    }
+    /* Mobile responsive styles */
+    @media (max-width: 600px) {
+      body {
+        padding: 10px;
+        font-size: 14px;
+      }
+      .card {
+        padding: 12px;
+        margin: 10px 0;
+      }
+      .page-header {
+        gap: 10px;
+        margin-bottom: 12px;
+        padding-bottom: 10px;
+      }
+      .page-header-left {
+        gap: 8px;
+      }
+      h1 {
+        font-size: 1.3em;
+      }
+      .breadcrumb-inline {
+        font-size: 0.95em;
+      }
+      .nav-links a {
+        padding: 8px 12px;
+        margin-right: 6px;
+        font-size: 0.9em;
+      }
+      .action-buttons {
+        gap: 6px;
+      }
+      .action-btn {
+        padding: 8px 10px;
+        font-size: 0.85em;
+      }
+      .file-table th,
+      .file-table td {
+        padding: 8px 6px;
+        font-size: 0.9em;
+      }
+      .file-table th {
+        font-size: 0.85em;
+      }
+      .file-icon {
+        margin-right: 4px;
+      }
+      .epub-badge,
+      .folder-badge {
+        padding: 2px 5px;
+        font-size: 0.65em;
+        margin-left: 4px;
+      }
+      .contents-header {
+        margin-bottom: 8px;
+        flex-wrap: wrap;
+        gap: 4px;
+      }
+      .contents-title {
+        font-size: 1em;
+      }
+      .summary-inline {
+        font-size: 0.8em;
+      }
+      .modal {
+        padding: 15px;
+      }
+      .modal h3 {
+        font-size: 1.1em;
+      }
+      .actions-col {
+        width: 40px;
+      }
+      .delete-btn {
+        font-size: 1em;
+        padding: 2px 4px;
+      }
+      .no-files {
+        padding: 20px;
+        font-size: 0.9em;
+      }
+    }
+  </style>
+</head>
+<body>
+<div class="nav-links">
+  <a href="/">Home</a>
+  <a href="/files">File Manager</a>
+</div>
+
+<div class="page-header">
+  <div class="page-header-left">
+    <h1>📁 File Manager</h1>
+    <div class="breadcrumb-inline" id="directory-breadcrumbs"></div>
+  </div>
+
+  <div class="action-buttons">
+    <button class="action-btn upload-action-btn" onclick="openUploadModal()">📤 Upload</button>
+    <button class="action-btn folder-action-btn" onclick="openFolderModal()">📁 New Folder</button>
+  </div>
+</div>
+
+<div class="card">
+  <div class="contents-header">
+    <h2 class="contents-title">Contents</h2>
+    <span class="summary-inline" id="folder-summary"></span>
+  </div>
+
+  <div id="file-table">
+    <div class="loader-container">
+      <span class="loader"></span>
+    </div>
+  </div>
+</div>
+
+<div class="card">
+  <p style="text-align: center; color: #95a5a6; margin: 0;">
+    CrossPoint E-Reader • Open Source
+  </p>
+</div>
+
+<!-- Upload Modal -->
+<div class="modal-overlay" id="uploadModal">
+  <div class="modal">
+    <button class="modal-close" onclick="closeUploadModal()">&times;</button>
+    <h3>📤 Upload file</h3>
+    <div class="upload-form">
+      <p class="file-info">Select a file to upload to <strong id="uploadPathDisplay"></strong></p>
+      <input type="file" id="fileInput" onchange="validateFile()">
+      <button id="uploadBtn" class="upload-btn" onclick="uploadFile()" disabled>Upload</button>
+      <div id="progress-container">
+        <div id="progress-bar"><div id="progress-fill"></div></div>
+        <div id="progress-text"></div>
+      </div>
+    </div>
+  </div>
+</div>
+
+<!-- New Folder Modal -->
+<div class="modal-overlay" id="folderModal">
+  <div class="modal">
+    <button class="modal-close" onclick="closeFolderModal()">&times;</button>
+    <h3>📁 New Folder</h3>
+    <div class="folder-form">
+      <p class="file-info">Create a new folder in <strong id="folderPathDisplay"></strong></p>
+      <input type="text" id="folderName" class="folder-input" placeholder="Folder name...">
+      <button class="folder-btn" onclick="createFolder()">Create Folder</button>
+    </div>
+  </div>
+</div>
+
+<!-- Delete Confirmation Modal -->
+<div class="modal-overlay" id="deleteModal">
+  <div class="modal">
+    <button class="modal-close" onclick="closeDeleteModal()">&times;</button>
+    <h3>🗑️ Delete Item</h3>
+    <div class="folder-form">
+      <p class="delete-warning">⚠️ This action cannot be undone!</p>
+      <p class="file-info">Are you sure you want to delete:</p>
+      <p class="delete-item-name" id="deleteItemName"></p>
+      <input type="hidden" id="deleteItemPath">
+      <input type="hidden" id="deleteItemType">
+      <button class="delete-btn-confirm" onclick="confirmDelete()">Delete</button>
+      <button class="delete-btn-cancel" onclick="closeDeleteModal()">Cancel</button>
+    </div>
+  </div>
+</div>
+
+<script>
+  // get current path from query parameter
+  const currentPath = decodeURIComponent(new URLSearchParams(window.location.search).get('path') || '/');
+
+  function escapeHtml(unsafe) {
+    return unsafe
+      .replaceAll("&", "&amp;")
+      .replaceAll("<", "&lt;")
+      .replaceAll(">", "&gt;")
+      .replaceAll('"', "&quot;")
+      .replaceAll("'", "&#039;");
+  }
+
+  function formatFileSize(bytes) {
+    if (bytes === 0) return '0 B';
+    const k = 1024;
+    const sizes = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
+    const i = Math.floor(Math.log(bytes) / Math.log(k));
+    return parseFloat((bytes / Math.pow(k, i)).toFixed(2)).toLocaleString() + ' ' + sizes[i];
+  }
+
+  async function hydrate() {
+    // Close modals when clicking overlay
+    document.querySelectorAll('.modal-overlay').forEach(function(overlay) {
+      overlay.addEventListener('click', function(e) {
+        if (e.target === overlay) {
+          overlay.classList.remove('open');
+        }
+      });
+    });
+
+    const breadcrumbs = document.getElementById('directory-breadcrumbs');
+    const fileTable = document.getElementById('file-table');
+
+    let breadcrumbContent = '<span class="sep">/</span>';
+    if (currentPath === '/') {
+      breadcrumbContent += '<span class="current">🏠</span>';
+    } else {
+      breadcrumbContent += '<a href="/files">🏠</a>';
+      const pathSegments = currentPath.split('/');
+      pathSegments.slice(1, pathSegments.length - 1).forEach(function(segment, index) {
+        breadcrumbContent += '<span class="sep">/</span><a href="/files?path=' + encodeURIComponent(pathSegments.slice(0, index + 2).join('/')) + '">' + escapeHtml(segment) + '</a>';
+      });
+      breadcrumbContent += '<span class="sep">/</span>';
+      breadcrumbContent += '<span class="current">' + escapeHtml(pathSegments[pathSegments.length - 1]) + '</span>';
+    }
+    breadcrumbs.innerHTML = breadcrumbContent;
+
+    let files = [];
+    try {
+      const response = await fetch('/api/files?path=' + encodeURIComponent(currentPath));
+      if (!response.ok) {
+        throw new Error('Failed to load files: ' + response.status + ' ' + response.statusText);
+      }
+      files = await response.json();
+    } catch (e) {
+      console.error(e);
+      fileTable.innerHTML = '<div class="no-files">An error occurred while loading the files</div>';
+      return;
+    }
+
+    let folderCount = 0;
+    let totalSize = 0;
+    files.forEach(file => {
+      if (file.isDirectory) folderCount++;
+      totalSize += file.size;
+    });
+
+    document.getElementById('folder-summary').innerHTML = `${folderCount} folders, ${files.length - folderCount} files, ${formatFileSize(totalSize)}`;
+
+    if (files.length === 0) {
+      fileTable.innerHTML = '<div class="no-files">This folder is empty</div>';
+    } else {
+      let fileTableContent = '<table class="file-table">';
+      fileTableContent += '<tr><th>Name</th><th>Type</th><th>Size</th><th class="actions-col">Actions</th></tr>';
+
+      const sortedFiles = files.sort((a, b) => {
+        // Directories first, then epub files, then other files, alphabetically within each group
+        if (a.isDirectory && !b.isDirectory) return -1;
+        if (!a.isDirectory && b.isDirectory) return 1;
+        if (a.isEpub && !b.isEpub) return -1;
+        if (!a.isEpub && b.isEpub) return 1;
+        return a.name.localeCompare(b.name);
+      });
+
+      sortedFiles.forEach(file => {
+        if (file.isDirectory) {
+          let folderPath = currentPath;
+          if (!folderPath.endsWith("/")) folderPath += "/";
+          folderPath += file.name;
+
+          fileTableContent += '<tr class="folder-row">';
+          fileTableContent += `<td><span class="file-icon">📁</span><a href="/files?path=${encodeURIComponent(folderPath)}" class="folder-link">${escapeHtml(file.name)}</a><span class="folder-badge">FOLDER</span></td>`;
+          fileTableContent += '<td>Folder</td>';
+          fileTableContent += '<td>-</td>';
+          fileTableContent += `<td class="actions-col"><button class="delete-btn" onclick="openDeleteModal('${file.name.replaceAll("'", "\\'")}', '${folderPath.replaceAll("'", "\\'")}', true)" title="Delete folder">🗑️</button></td>`;
+          fileTableContent += '</tr>';
+        } else {
+          let filePath = currentPath;
+          if (!filePath.endsWith("/")) filePath += "/";
+          filePath += file.name;
+
+          fileTableContent += `<tr class="${file.isEpub ? 'epub-file' : ''}">`;
+          fileTableContent += `<td><span class="file-icon">${file.isEpub ? '📗' : '📄'}</span>${escapeHtml(file.name)}`;
+          if (file.isEpub) fileTableContent += '<span class="epub-badge">EPUB</span>';
+          fileTableContent += '</td>';
+          fileTableContent += `<td>${file.name.split('.').pop().toUpperCase()}</td>`;
+          fileTableContent += `<td>${formatFileSize(file.size)}</td>`;
+          fileTableContent += `<td class="actions-col"><button class="delete-btn" onclick="openDeleteModal('${file.name.replaceAll("'", "\\'")}', '${filePath.replaceAll("'", "\\'")}', false)" title="Delete file">🗑️</button></td>`;
+          fileTableContent += '</tr>';
+        }
+      });
+
+      fileTableContent += '</table>';
+      fileTable.innerHTML = fileTableContent;
+    }
+  }
+
+  // Modal functions
+  function openUploadModal() {
+    document.getElementById('uploadPathDisplay').textContent = currentPath === '/' ? '/ 🏠' : currentPath;
+    document.getElementById('uploadModal').classList.add('open');
+  }
+
+  function closeUploadModal() {
+    document.getElementById('uploadModal').classList.remove('open');
+    document.getElementById('fileInput').value = '';
+    document.getElementById('uploadBtn').disabled = true;
+    document.getElementById('progress-container').style.display = 'none';
+    document.getElementById('progress-fill').style.width = '0%';
+    document.getElementById('progress-fill').style.backgroundColor = '#27ae60';
+  }
+
+  function openFolderModal() {
+    document.getElementById('folderPathDisplay').textContent = currentPath === '/' ? '/ 🏠' : currentPath;
+    document.getElementById('folderModal').classList.add('open');
+    document.getElementById('folderName').value = '';
+  }
+
+  function closeFolderModal() {
+    document.getElementById('folderModal').classList.remove('open');
+  }
+
+  function validateFile() {
+    const fileInput = document.getElementById('fileInput');
+    const uploadBtn = document.getElementById('uploadBtn');
+    const file = fileInput.files[0];
+    uploadBtn.disabled = !file;
+  }
+
+  function uploadFile() {
+    const fileInput = document.getElementById('fileInput');
+    const file = fileInput.files[0];
+
+    if (!file) {
+      alert('Please select a file first!');
+      return;
+    }
+
+    const formData = new FormData();
+    formData.append('file', file);
+
+    const progressContainer = document.getElementById('progress-container');
+    const progressFill = document.getElementById('progress-fill');
+    const progressText = document.getElementById('progress-text');
+    const uploadBtn = document.getElementById('uploadBtn');
+
+    progressContainer.style.display = 'block';
+    uploadBtn.disabled = true;
+
+    const xhr = new XMLHttpRequest();
+    // Include path as query parameter since multipart form data doesn't make
+    // form fields available until after file upload completes
+    xhr.open('POST', '/upload?path=' + encodeURIComponent(currentPath), true);
+
+    xhr.upload.onprogress = function(e) {
+      if (e.lengthComputable) {
+        const percent = Math.round((e.loaded / e.total) * 100);
+        progressFill.style.width = percent + '%';
+        progressText.textContent = 'Uploading: ' + percent + '%';
+      }
+    };
+
+    xhr.onload = function() {
+      if (xhr.status === 200) {
+        progressText.textContent = 'Upload complete!';
+        setTimeout(function() {
+          window.location.reload();
+        }, 1000);
+      } else {
+        progressText.textContent = 'Upload failed: ' + xhr.responseText;
+        progressFill.style.backgroundColor = '#e74c3c';
+        uploadBtn.disabled = false;
+      }
+    };
+
+    xhr.onerror = function() {
+      progressText.textContent = 'Upload failed - network error';
+      progressFill.style.backgroundColor = '#e74c3c';
+      uploadBtn.disabled = false;
+    };
+
+    xhr.send(formData);
+  }
+
+  function createFolder() {
+    const folderName = document.getElementById('folderName').value.trim();
+
+    if (!folderName) {
+      alert('Please enter a folder name!');
+      return;
+    }
+
+    // Validate folder name (no special characters except underscore and hyphen)
+    const validName = /^[a-zA-Z0-9_\-]+$/.test(folderName);
+    if (!validName) {
+      alert('Folder name can only contain letters, numbers, underscores, and hyphens.');
+      return;
+    }
+
+    const formData = new FormData();
+    formData.append('name', folderName);
+    formData.append('path', currentPath);
+
+    const xhr = new XMLHttpRequest();
+    xhr.open('POST', '/mkdir', true);
+
+    xhr.onload = function() {
+      if (xhr.status === 200) {
+        window.location.reload();
+      } else {
+        alert('Failed to create folder: ' + xhr.responseText);
+      }
+    };
+
+    xhr.onerror = function() {
+      alert('Failed to create folder - network error');
+    };
+
+    xhr.send(formData);
+  }
+
+  // Delete functions
+  function openDeleteModal(name, path, isFolder) {
+    document.getElementById('deleteItemName').textContent = (isFolder ? '📁 ' : '📄 ') + name;
+    document.getElementById('deleteItemPath').value = path;
+    document.getElementById('deleteItemType').value = isFolder ? 'folder' : 'file';
+    document.getElementById('deleteModal').classList.add('open');
+  }
+
+  function closeDeleteModal() {
+    document.getElementById('deleteModal').classList.remove('open');
+  }
+
+  function confirmDelete() {
+    const path = document.getElementById('deleteItemPath').value;
+    const itemType = document.getElementById('deleteItemType').value;
+
+    const formData = new FormData();
+    formData.append('path', path);
+    formData.append('type', itemType);
+
+    const xhr = new XMLHttpRequest();
+    xhr.open('POST', '/delete', true);
+
+    xhr.onload = function() {
+      if (xhr.status === 200) {
+        window.location.reload();
+      } else {
+        alert('Failed to delete: ' + xhr.responseText);
+        closeDeleteModal();
+      }
+    };
+
+    xhr.onerror = function() {
+      alert('Failed to delete - network error');
+      closeDeleteModal();
+    };
+
+    xhr.send(formData);
+  }
+
+  hydrate();
+</script>
+</body>
+</html>

src/network/html/HomePage.html

@@ -83,7 +83,7 @@
       <h2>Device Status</h2>
       <div class="info-row">
         <span class="label">Version</span>
-        <span class="value">%VERSION%</span>
+        <span class="value" id="version"></span>
       </div>
       <div class="info-row">
         <span class="label">WiFi Status</span>
@@ -91,11 +91,11 @@
       </div>
       <div class="info-row">
         <span class="label">IP Address</span>
-        <span class="value">%IP_ADDRESS%</span>
+        <span class="value" id="ip-address"></span>
       </div>
       <div class="info-row">
         <span class="label">Free Memory</span>
-        <span class="value">%FREE_HEAP% bytes</span>
+        <span class="value" id="free-heap"></span>
       </div>
     </div>
 
@@ -104,5 +104,26 @@
         CrossPoint E-Reader • Open Source
       </p>
     </div>
+  <script>
+    async function fetchStatus() {
+      try {
+        const response = await fetch('/api/status');
+        if (!response.ok) {
+          throw new Error('Failed to fetch status: ' + response.status + ' ' + response.statusText);
+        }
+        const data = await response.json();
+        document.getElementById('version').textContent = data.version || 'N/A';
+        document.getElementById('ip-address').textContent = data.ip || 'N/A';
+        document.getElementById('free-heap').textContent = data.freeHeap
+          ? data.freeHeap.toLocaleString() + ' bytes'
+          : 'N/A';
+      } catch (error) {
+        console.error('Error fetching status:', error);
+      }
+    }
+
+    // Fetch status on page load
+    window.onload = fetchStatus;
+  </script>
   </body>
 </html>