refactor: Removed redundant FsFile close() calls (#1434)

## Summary

**What is the goal of this PR?** (e.g., Implements the new feature for
file uploading.)

`DESTRUCTOR_CLOSES_FILE=1` is set in platformio.ini, which makes SdFat's
FsBaseFile destructor call close() automatically when a file goes out of
scope.

Three categories of file close calls remain untouched:
1. Close before Storage.remove() on the same path: ScreenshotUtil.cpp
closes the file before deleting it on write error. The remove might fail
if the file is still open.
2. Close before reopening the same variable: Epub.cpp writes a temp
NCX/nav file, closes it, then reopens it for reading. The
RecentBooksStore.cpp close before saveToFile() is the same pattern, it
rewrites the same file.
3. Close on member variables: BookMetadataCache.cpp (bookFile,
spineFile, tocFile), Section.cpp (file), XtcParser.cpp (m_file),
ZipFile.cpp (file). These persist beyond any single function scope, so
the destructor timing doesn't match the intended close point.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**PARTIALLY**_

lib/Epub/Epub.cpp

@@ -155,6 +155,7 @@ bool Epub::parseTocNcxFile() const {
     return false;
   }
   readItemContentsToStream(tocNcxItem, tempNcxFile, 1024);
+  // Explicitly close() file before reopening for reading
   tempNcxFile.close();
   if (!Storage.openFileForRead("EBP", tmpNcxPath, tempNcxFile)) {
     return false;
@@ -165,14 +166,12 @@ bool Epub::parseTocNcxFile() const {
 
   if (!ncxParser.setup()) {
     LOG_ERR("EBP", "Could not setup toc ncx parser");
-    tempNcxFile.close();
     return false;
   }
 
   const auto ncxBuffer = static_cast<uint8_t*>(malloc(1024));
   if (!ncxBuffer) {
     LOG_ERR("EBP", "Could not allocate memory for toc ncx parser");
-    tempNcxFile.close();
     return false;
   }
 
@@ -184,12 +183,12 @@ bool Epub::parseTocNcxFile() const {
     if (processedSize != readSize) {
       LOG_ERR("EBP", "Could not process all toc ncx data");
       free(ncxBuffer);
-      tempNcxFile.close();
       return false;
     }
   }
 
   free(ncxBuffer);
+  // Explicitly close() file before calling Storage.remove()
   tempNcxFile.close();
   Storage.remove(tmpNcxPath.c_str());
 
@@ -212,6 +211,7 @@ bool Epub::parseTocNavFile() const {
     return false;
   }
   readItemContentsToStream(tocNavItem, tempNavFile, 1024);
+  // Explicitly close() file before reopening for reading
   tempNavFile.close();
   if (!Storage.openFileForRead("EBP", tmpNavPath, tempNavFile)) {
     return false;
@@ -241,12 +241,12 @@ bool Epub::parseTocNavFile() const {
     if (processedSize != readSize) {
       LOG_ERR("EBP", "Could not process all toc nav data");
       free(navBuffer);
-      tempNavFile.close();
       return false;
     }
   }
 
   free(navBuffer);
+  // Explicitly close() file before calling Storage.remove()
   tempNavFile.close();
   Storage.remove(tmpNavPath.c_str());
 
@@ -304,10 +304,12 @@ void Epub::parseCssFiles() const {
     }
     if (!readItemContentsToStream(cssPath, tempCssFile, 1024)) {
       LOG_ERR("EBP", "Could not read CSS file: %s", cssPath.c_str());
+      // Explicitly close() file before calling Storage.remove()
       tempCssFile.close();
       Storage.remove(tmpCssPath.c_str());
       continue;
     }
+    // Explicitly close() file before reopening for reading
     tempCssFile.close();
 
     // Parse the CSS file
@@ -317,6 +319,7 @@ void Epub::parseCssFiles() const {
       continue;
     }
     cssParser->loadFromStream(tempCssFile);
+    // Explicitly close() file before calling Storage.remove()
     tempCssFile.close();
     Storage.remove(tmpCssPath.c_str());
   }
@@ -547,6 +550,7 @@ bool Epub::generateCoverBmp(bool cropped) const {
       return false;
     }
     readItemContentsToStream(coverImageHref, coverJpg, 1024);
+    // Explicitly close() file before reopening for reading
     coverJpg.close();
 
     if (!Storage.openFileForRead("EBP", coverJpgTempPath, coverJpg)) {
@@ -555,10 +559,10 @@ bool Epub::generateCoverBmp(bool cropped) const {
 
     FsFile coverBmp;
     if (!Storage.openFileForWrite("EBP", getCoverBmpPath(cropped), coverBmp)) {
-      coverJpg.close();
       return false;
     }
     const bool success = JpegToBmpConverter::jpegFileToBmpStream(coverJpg, coverBmp, cropped);
+    // Explicitly close() files before calling Storage.remove()
     coverJpg.close();
     coverBmp.close();
     Storage.remove(coverJpgTempPath.c_str());
@@ -580,6 +584,7 @@ bool Epub::generateCoverBmp(bool cropped) const {
       return false;
     }
     readItemContentsToStream(coverImageHref, coverPng, 1024);
+    // Explicitly close() file before reopening for reading
     coverPng.close();
 
     if (!Storage.openFileForRead("EBP", coverPngTempPath, coverPng)) {
@@ -588,10 +593,10 @@ bool Epub::generateCoverBmp(bool cropped) const {
 
     FsFile coverBmp;
     if (!Storage.openFileForWrite("EBP", getCoverBmpPath(cropped), coverBmp)) {
-      coverPng.close();
       return false;
     }
     const bool success = PngToBmpConverter::pngFileToBmpStream(coverPng, coverBmp, cropped);
+    // Explicitly close() files before calling Storage.remove()
     coverPng.close();
     coverBmp.close();
     Storage.remove(coverPngTempPath.c_str());
@@ -634,6 +639,7 @@ bool Epub::generateThumbBmp(int height) const {
       return false;
     }
     readItemContentsToStream(coverImageHref, coverJpg, 1024);
+    // Explicitly close() file before reopening for reading
     coverJpg.close();
 
     if (!Storage.openFileForRead("EBP", coverJpgTempPath, coverJpg)) {
@@ -642,7 +648,6 @@ bool Epub::generateThumbBmp(int height) const {
 
     FsFile thumbBmp;
     if (!Storage.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp)) {
-      coverJpg.close();
       return false;
     }
     // Use smaller target size for Continue Reading card (half of screen: 240x400)
@@ -651,6 +656,7 @@ bool Epub::generateThumbBmp(int height) const {
     int THUMB_TARGET_HEIGHT = height;
     const bool success = JpegToBmpConverter::jpegFileTo1BitBmpStreamWithSize(coverJpg, thumbBmp, THUMB_TARGET_WIDTH,
                                                                              THUMB_TARGET_HEIGHT);
+    // Explicitly close() files before calling Storage.remove()
     coverJpg.close();
     thumbBmp.close();
     Storage.remove(coverJpgTempPath.c_str());
@@ -670,6 +676,7 @@ bool Epub::generateThumbBmp(int height) const {
       return false;
     }
     readItemContentsToStream(coverImageHref, coverPng, 1024);
+    // Explicitly close() file before reopening for reading
     coverPng.close();
 
     if (!Storage.openFileForRead("EBP", coverPngTempPath, coverPng)) {
@@ -678,13 +685,13 @@ bool Epub::generateThumbBmp(int height) const {
 
     FsFile thumbBmp;
     if (!Storage.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp)) {
-      coverPng.close();
       return false;
     }
     int THUMB_TARGET_WIDTH = height * 0.6;
     int THUMB_TARGET_HEIGHT = height;
     const bool success =
         PngToBmpConverter::pngFileTo1BitBmpStreamWithSize(coverPng, thumbBmp, THUMB_TARGET_WIDTH, THUMB_TARGET_HEIGHT);
+    // Explicitly close() files before calling Storage.remove()
     coverPng.close();
     thumbBmp.close();
     Storage.remove(coverPngTempPath.c_str());
@@ -702,7 +709,6 @@ bool Epub::generateThumbBmp(int height) const {
   // Write an empty bmp file to avoid generation attempts in the future
   FsFile thumbBmp;
   Storage.openFileForWrite("EBP", getThumbBmpPath(height), thumbBmp);
-  thumbBmp.close();
   return false;
 }
 

lib/Epub/Epub/BookMetadataCache.cpp

@@ -33,6 +33,7 @@ bool BookMetadataCache::beginContentOpfPass() {
 }
 
 bool BookMetadataCache::endContentOpfPass() {
+  // Explicit close() required: member variable persists beyond function scope
   spineFile.close();
   return true;
 }
@@ -44,6 +45,7 @@ bool BookMetadataCache::beginTocPass() {
     return false;
   }
   if (!Storage.openFileForWrite("BMC", cachePath + tmpTocBinFile, tocFile)) {
+    // Explicit close() required: member variable persists beyond function scope
     spineFile.close();
     return false;
   }
@@ -75,6 +77,7 @@ bool BookMetadataCache::beginTocPass() {
 }
 
 bool BookMetadataCache::endTocPass() {
+  // Explicit close() required: member variables persist beyond function scope
   tocFile.close();
   spineFile.close();
 
@@ -103,11 +106,13 @@ bool BookMetadataCache::buildBookBin(const std::string& epubPath, const BookMeta
   }
 
   if (!Storage.openFileForRead("BMC", cachePath + tmpSpineBinFile, spineFile)) {
+    // Explicit close() required: member variable persists beyond function scope
     bookFile.close();
     return false;
   }
 
   if (!Storage.openFileForRead("BMC", cachePath + tmpTocBinFile, tocFile)) {
+    // Explicit close() required: member variables persist beyond function scope
     bookFile.close();
     spineFile.close();
     return false;
@@ -168,6 +173,7 @@ bool BookMetadataCache::buildBookBin(const std::string& epubPath, const BookMeta
   // Pre-open zip file to speed up size calculations
   if (!zip.open()) {
     LOG_ERR("BMC", "Could not open EPUB zip for size calculations");
+    // Explicit close() required: member variables persist beyond function scope
     bookFile.close();
     spineFile.close();
     tocFile.close();
@@ -265,6 +271,7 @@ bool BookMetadataCache::buildBookBin(const std::string& epubPath, const BookMeta
     writeTocEntry(bookFile, tocEntry);
   }
 
+  // Explicit close() required: member variables persist beyond function scope
   bookFile.close();
   spineFile.close();
   tocFile.close();
@@ -373,6 +380,7 @@ bool BookMetadataCache::load() {
   serialization::readPod(bookFile, version);
   if (version != BOOK_CACHE_VERSION) {
     LOG_DBG("BMC", "Cache version mismatch: expected %d, got %d", BOOK_CACHE_VERSION, version);
+    // Explicit close() required: member variable persists beyond function scope
     bookFile.close();
     return false;
   }

lib/Epub/Epub/Section.cpp

@@ -74,6 +74,7 @@ bool Section::loadSectionFile(const int fontId, const float lineCompression, con
     uint8_t version;
     serialization::readPod(file, version);
     if (version != SECTION_FILE_VERSION) {
+      // Explicit close() required: member variable persists beyond function scope
       file.close();
       LOG_ERR("SCT", "Deserialization failed: Unknown version %u", version);
       clearCache();
@@ -103,6 +104,7 @@ bool Section::loadSectionFile(const int fontId, const float lineCompression, con
         viewportWidth != fileViewportWidth || viewportHeight != fileViewportHeight ||
         hyphenationEnabled != fileHyphenationEnabled || embeddedStyle != fileEmbeddedStyle ||
         imageRendering != fileImageRendering) {
+      // Explicit close() required: member variable persists beyond function scope
       file.close();
       LOG_ERR("SCT", "Deserialization failed: Parameters do not match");
       clearCache();
@@ -111,6 +113,7 @@ bool Section::loadSectionFile(const int fontId, const float lineCompression, con
   }
 
   serialization::readPod(file, pageCount);
+  // Explicit close() required: member variable persists beyond function scope
   file.close();
   LOG_DBG("SCT", "Deserialization succeeded: %d pages", pageCount);
   return true;
@@ -165,6 +168,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
     }
     success = epub->readItemContentsToStream(localPath, tmpHtml, 1024);
     fileSize = tmpHtml.size();
+    // Explicitly close() file before calling Storage.remove()
     tmpHtml.close();
 
     // If streaming failed, remove the incomplete file immediately
@@ -214,6 +218,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
   Storage.remove(tmpHtmlPath.c_str());
   if (!success) {
     LOG_ERR("SCT", "Failed to parse XML and build pages");
+    // Explicitly close() file before calling Storage.remove()
     file.close();
     Storage.remove(filePath.c_str());
     if (cssParser) {
@@ -235,6 +240,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
 
   if (hasFailedLutRecords) {
     LOG_ERR("SCT", "Failed to write LUT due to invalid page positions");
+    // Explicitly close() file before calling Storage.remove()
     file.close();
     Storage.remove(filePath.c_str());
     return false;
@@ -254,6 +260,7 @@ bool Section::createSectionFile(const int fontId, const float lineCompression, c
   serialization::writePod(file, pageCount);
   serialization::writePod(file, lutOffset);
   serialization::writePod(file, anchorMapOffset);
+  // Explicit close() required: member variable persists beyond function scope
   file.close();
   if (cssParser) {
     cssParser->clear();
@@ -275,6 +282,7 @@ std::unique_ptr<Page> Section::loadPageFromSectionFile() {
   file.seek(pagePos);
 
   auto page = Page::deserialize(file);
+  // Explicit close() required: member variable persists beyond function scope
   file.close();
   return page;
 }
@@ -290,7 +298,6 @@ std::optional<uint16_t> Section::getPageForAnchor(const std::string& anchor) con
   uint32_t anchorMapOffset;
   serialization::readPod(f, anchorMapOffset);
   if (anchorMapOffset == 0 || anchorMapOffset >= fileSize) {
-    f.close();
     return std::nullopt;
   }
 
@@ -303,11 +310,9 @@ std::optional<uint16_t> Section::getPageForAnchor(const std::string& anchor) con
     serialization::readString(f, key);
     serialization::readPod(f, page);
     if (key == anchor) {
-      f.close();
       return page;
     }
   }
 
-  f.close();
   return std::nullopt;
 }

lib/Epub/Epub/blocks/ImageBlock.cpp

@@ -37,7 +37,6 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
 
   uint16_t cachedWidth, cachedHeight;
   if (cacheFile.read(&cachedWidth, 2) != 2 || cacheFile.read(&cachedHeight, 2) != 2) {
-    cacheFile.close();
     return false;
   }
 
@@ -47,7 +46,6 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
   if (widthDiff > 1 || heightDiff > 1) {
     LOG_ERR("IMG", "Cache dimension mismatch: %dx%d vs %dx%d", cachedWidth, cachedHeight, expectedWidth,
             expectedHeight);
-    cacheFile.close();
     return false;
   }
 
@@ -62,7 +60,6 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
   uint8_t* rowBuffer = (uint8_t*)malloc(bytesPerRow);
   if (!rowBuffer) {
     LOG_ERR("IMG", "Failed to allocate row buffer");
-    cacheFile.close();
     return false;
   }
 
@@ -73,7 +70,6 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
     if (cacheFile.read(rowBuffer, bytesPerRow) != bytesPerRow) {
       LOG_ERR("IMG", "Cache read error at row %d", row);
       free(rowBuffer);
-      cacheFile.close();
       return false;
     }
 
@@ -89,7 +85,6 @@ bool renderFromCache(GfxRenderer& renderer, const std::string& cachePath, int x,
   }
 
   free(rowBuffer);
-  cacheFile.close();
   LOG_DBG("IMG", "Cache render complete");
   return true;
 }

lib/Epub/Epub/css/CssParser.cpp

@@ -743,7 +743,6 @@ bool CssParser::saveToCache() const {
   }
 
   LOG_DBG("CSS", "Saved %u rules to cache", ruleCount);
-  file.close();
   return true;
 }
 
@@ -765,6 +764,7 @@ bool CssParser::loadFromCache() {
   if (file.read(&version, 1) != 1 || version != CssParser::CSS_CACHE_VERSION) {
     LOG_DBG("CSS", "Cache version mismatch (got %u, expected %u), removing stale cache for rebuild", version,
             CssParser::CSS_CACHE_VERSION);
+    // Explicitly close() file before calling Storage.remove()
     file.close();
     Storage.remove((cachePath + rulesCache).c_str());
     return false;
@@ -773,14 +773,12 @@ bool CssParser::loadFromCache() {
   // Read rule count
   uint16_t ruleCount = 0;
   if (file.read(&ruleCount, sizeof(ruleCount)) != sizeof(ruleCount)) {
-    file.close();
     return false;
   }
 
   if (ruleCount > MAX_RULES) {
     LOG_DBG("CSS", "Invalid cache rule count (%u > %zu)", ruleCount, MAX_RULES);
     rulesBySelector_.clear();
-    file.close();
     return false;
   }
 
@@ -799,19 +797,16 @@ bool CssParser::loadFromCache() {
     uint16_t selectorLen = 0;
     if (!hasRemainingBytes(sizeof(selectorLen))) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     if (file.read(&selectorLen, sizeof(selectorLen)) != sizeof(selectorLen)) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
 
     if (selectorLen == 0 || selectorLen > MAX_SELECTOR_LENGTH || !hasRemainingBytes(selectorLen)) {
       LOG_DBG("CSS", "Invalid selector length in cache: %u", selectorLen);
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
 
@@ -819,14 +814,12 @@ bool CssParser::loadFromCache() {
     selector.resize(selectorLen);
     if (file.read(&selector[0], selectorLen) != selectorLen) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
 
     if (!hasRemainingBytes(CSS_FIXED_STYLE_BYTES)) {
       LOG_DBG("CSS", "Truncated CSS cache while reading style payload");
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
 
@@ -836,28 +829,24 @@ bool CssParser::loadFromCache() {
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.textAlign = static_cast<CssTextAlign>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.fontStyle = static_cast<CssFontStyle>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.fontWeight = static_cast<CssFontWeight>(enumVal);
 
     if (file.read(&enumVal, 1) != 1) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.textDecoration = static_cast<CssTextDecoration>(enumVal);
@@ -880,7 +869,6 @@ bool CssParser::loadFromCache() {
         !readLength(style.paddingBottom) || !readLength(style.paddingLeft) || !readLength(style.paddingRight) ||
         !readLength(style.imageHeight) || !readLength(style.imageWidth)) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
 
@@ -888,7 +876,6 @@ bool CssParser::loadFromCache() {
     uint8_t displayVal;
     if (file.read(&displayVal, 1) != 1) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.display = static_cast<CssDisplay>(displayVal);
@@ -897,7 +884,6 @@ bool CssParser::loadFromCache() {
     uint16_t definedBits = 0;
     if (file.read(&definedBits, sizeof(definedBits)) != sizeof(definedBits)) {
       rulesBySelector_.clear();
-      file.close();
       return false;
     }
     style.defined.textAlign = (definedBits & 1 << 0) != 0;
@@ -921,6 +907,5 @@ bool CssParser::loadFromCache() {
   }
 
   LOG_DBG("CSS", "Loaded %u rules from cache", ruleCount);
-  file.close();
   return true;
 }

lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp

@@ -1018,7 +1018,6 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
       XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
       XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      file.close();
       return false;
     }
 
@@ -1030,7 +1029,6 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
       XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
       XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      file.close();
       return false;
     }
 
@@ -1043,7 +1041,6 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
       XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
       XML_SetCharacterDataHandler(parser, nullptr);
       XML_ParserFree(parser);
-      file.close();
       return false;
     }
   } while (!done);
@@ -1053,7 +1050,6 @@ bool ChapterHtmlSlimParser::parseAndBuildPages() {
   XML_SetElementHandler(parser, nullptr, nullptr);  // Clear callbacks
   XML_SetCharacterDataHandler(parser, nullptr);
   XML_ParserFree(parser);
-  file.close();
 
   // Process last page if there is still text
   if (currentTextBlock) {

lib/I18n/I18n.cpp

@@ -71,7 +71,6 @@ void I18n::loadSettings() {
   serialization::readPod(file, version);
   if (version != SETTINGS_VERSION) {
     Serial.printf("[I18N] Settings version mismatch\n");
-    file.close();
     return;
   }
 
@@ -81,8 +80,6 @@ void I18n::loadSettings() {
     _language = static_cast<Language>(lang);
     Serial.printf("[I18N] Loaded language: %d\n", static_cast<int>(_language));
   }
-
-  file.close();
 }
 
 // Generate character set for a specific language

lib/KOReaderSync/KOReaderCredentialStore.cpp

@@ -82,7 +82,6 @@ bool KOReaderCredentialStore::loadFromBinaryFile() {
   serialization::readPod(file, version);
   if (version != KOREADER_FILE_VERSION) {
     LOG_DBG("KRS", "Unknown file version: %u", version);
-    file.close();
     return false;
   }
 
@@ -113,7 +112,6 @@ bool KOReaderCredentialStore::loadFromBinaryFile() {
     matchMethod = DocumentMatchMethod::FILENAME;
   }
 
-  file.close();
   LOG_DBG("KRS", "Loaded KOReader credentials from binary for user: %s", username.c_str());
   return true;
 }

lib/KOReaderSync/KOReaderDocumentId.cpp

@@ -84,8 +84,6 @@ std::string KOReaderDocumentId::calculate(const std::string& filePath) {
     }
   }
 
-  file.close();
-
   // Calculate final hash
   md5.calculate();
   std::string result = md5.toString().c_str();

lib/Txt/Txt.cpp

@@ -120,7 +120,6 @@ bool Txt::generateCoverBmp() const {
       return false;
     }
     if (!Storage.openFileForWrite("TXT", getCoverBmpPath(), dst)) {
-      src.close();
       return false;
     }
     uint8_t buffer[1024];
@@ -128,8 +127,6 @@ bool Txt::generateCoverBmp() const {
       size_t bytesRead = src.read(buffer, sizeof(buffer));
       dst.write(buffer, bytesRead);
     }
-    src.close();
-    dst.close();
     LOG_DBG("TXT", "Copied BMP cover to cache");
     return true;
   } else if (FsHelpers::hasJpgExtension(coverImagePath)) {
@@ -140,12 +137,9 @@ bool Txt::generateCoverBmp() const {
       return false;
     }
     if (!Storage.openFileForWrite("TXT", getCoverBmpPath(), coverBmp)) {
-      coverJpg.close();
       return false;
     }
     const bool success = JpegToBmpConverter::jpegFileToBmpStream(coverJpg, coverBmp);
-    coverJpg.close();
-    coverBmp.close();
 
     if (!success) {
       LOG_ERR("TXT", "Failed to generate BMP from JPG cover image");
@@ -172,12 +166,9 @@ bool Txt::readContent(uint8_t* buffer, size_t offset, size_t length) const {
   }
 
   if (!file.seek(offset)) {
-    file.close();
     return false;
   }
 
   size_t bytesRead = file.read(buffer, length);
-  file.close();
-
   return bytesRead > 0;
 }

lib/Xtc/Xtc.cpp

@@ -199,7 +199,6 @@ bool Xtc::generateCoverBmp() const {
     uint8_t* rowBuffer = static_cast<uint8_t*>(malloc(dstRowSize));
     if (!rowBuffer) {
       free(pageBuffer);
-      coverBmp.close();
       return false;
     }
 
@@ -255,7 +254,6 @@ bool Xtc::generateCoverBmp() const {
     }
   }
 
-  coverBmp.close();
   free(pageBuffer);
 
   LOG_DBG("XTC", "Generated cover BMP: %s", getCoverBmpPath().c_str());
@@ -316,9 +314,7 @@ bool Xtc::generateThumbBmp(int height) const {
             size_t bytesRead = src.read(buffer, sizeof(buffer));
             dst.write(buffer, bytesRead);
           }
-          dst.close();
         }
-        src.close();
       }
       LOG_DBG("XTC", "Copied cover to thumb (no scaling needed)");
       return Storage.exists(getThumbBmpPath(height).c_str());
@@ -372,7 +368,6 @@ bool Xtc::generateThumbBmp(int height) const {
   uint8_t* rowBuffer = static_cast<uint8_t*>(malloc(rowSize));
   if (!rowBuffer) {
     free(pageBuffer);
-    thumbBmp.close();
     return false;
   }
 
@@ -479,7 +474,6 @@ bool Xtc::generateThumbBmp(int height) const {
   }
 
   free(rowBuffer);
-  thumbBmp.close();
   free(pageBuffer);
 
   LOG_DBG("XTC", "Generated thumb BMP (%dx%d): %s", thumbWidth, thumbHeight, getThumbBmpPath(height).c_str());

lib/Xtc/Xtc/XtcParser.cpp

@@ -43,6 +43,7 @@ XtcError XtcParser::open(const char* filepath) {
   m_lastError = readHeader();
   if (m_lastError != XtcError::OK) {
     LOG_DBG("XTC", "Failed to read header: %s", errorToString(m_lastError));
+    // Explicit close() required: member variable persists beyond function scope
     m_file.close();
     return m_lastError;
   }
@@ -52,12 +53,14 @@ XtcError XtcParser::open(const char* filepath) {
     m_lastError = readTitle();
     if (m_lastError != XtcError::OK) {
       LOG_DBG("XTC", "Failed to read title: %s", errorToString(m_lastError));
+      // Explicit close() required: member variable persists beyond function scope
       m_file.close();
       return m_lastError;
     }
     m_lastError = readAuthor();
     if (m_lastError != XtcError::OK) {
       LOG_DBG("XTC", "Failed to read author: %s", errorToString(m_lastError));
+      // Explicit close() required: member variable persists beyond function scope
       m_file.close();
       return m_lastError;
     }
@@ -67,6 +70,7 @@ XtcError XtcParser::open(const char* filepath) {
   m_lastError = readPageTable();
   if (m_lastError != XtcError::OK) {
     LOG_DBG("XTC", "Failed to read page table: %s", errorToString(m_lastError));
+    // Explicit close() required: member variable persists beyond function scope
     m_file.close();
     return m_lastError;
   }
@@ -75,6 +79,7 @@ XtcError XtcParser::open(const char* filepath) {
   m_lastError = readChapters();
   if (m_lastError != XtcError::OK) {
     LOG_DBG("XTC", "Failed to read chapters: %s", errorToString(m_lastError));
+    // Explicit close() required: member variable persists beyond function scope
     m_file.close();
     return m_lastError;
   }
@@ -86,6 +91,7 @@ XtcError XtcParser::open(const char* filepath) {
 
 void XtcParser::close() {
   if (m_isOpen) {
+    // Explicit close() required: member variable persists beyond function scope
     m_file.close();
     m_isOpen = false;
   }

lib/ZipFile/ZipFile.cpp

@@ -278,6 +278,7 @@ bool ZipFile::open() {
 
 bool ZipFile::close() {
   if (file) {
+    // Explicit close() required: member variable persists beyond function scope
     file.close();
   }
   lastCentralDirPos = 0;

src/CrossPointSettings.cpp

@@ -126,7 +126,6 @@ bool CrossPointSettings::loadFromBinaryFile() {
   serialization::readPod(inputFile, version);
   if (version != SETTINGS_FILE_VERSION) {
     LOG_ERR("CPS", "Deserialization failed: Unknown version %u", version);
-    inputFile.close();
     return false;
   }
 
@@ -220,7 +219,6 @@ bool CrossPointSettings::loadFromBinaryFile() {
     applyLegacyFrontButtonLayout(*this);
   }
 
-  inputFile.close();
   LOG_DBG("CPS", "Settings loaded from binary file");
   return true;
 }

src/CrossPointState.cpp

@@ -55,7 +55,6 @@ bool CrossPointState::loadFromBinaryFile() {
   serialization::readPod(inputFile, version);
   if (version > STATE_FILE_VERSION) {
     LOG_ERR("CPS", "Deserialization failed: Unknown version %u", version);
-    inputFile.close();
     return false;
   }
 
@@ -76,6 +75,5 @@ bool CrossPointState::loadFromBinaryFile() {
     lastSleepFromReader = false;
   }
 
-  inputFile.close();
   return true;
 }

src/RecentBooksStore.cpp

@@ -163,6 +163,7 @@ bool RecentBooksStore::loadFromBinaryFile() {
     }
 
     if (omitted > 0) {
+      // Explicitly close() file before saveToFile() rewrites the same file
       inputFile.close();
       saveToFile();
       LOG_DBG("RBS", "Omitted %u recent book(s) with missing title", omitted);
@@ -170,11 +171,9 @@ bool RecentBooksStore::loadFromBinaryFile() {
     }
   } else {
     LOG_ERR("RBS", "Deserialization failed: Unknown version %u", version);
-    inputFile.close();
     return false;
   }
 
-  inputFile.close();
   LOG_DBG("RBS", "Recent books loaded from binary file (%d entries)", static_cast<int>(recentBooks.size()));
   return true;
 }

src/WifiCredentialStore.cpp

@@ -76,7 +76,6 @@ bool WifiCredentialStore::loadFromBinaryFile() {
   serialization::readPod(file, version);
   if (version > WIFI_FILE_VERSION) {
     LOG_DBG("WCS", "Unknown file version: %u", version);
-    file.close();
     return false;
   }
 
@@ -98,7 +97,6 @@ bool WifiCredentialStore::loadFromBinaryFile() {
     credentials.push_back(cred);
   }
 
-  file.close();
   // LOG_DBG("WCS", "Loaded %zu WiFi credentials from binary file", credentials.size());
   return true;
 }

src/activities/boot_sleep/SleepActivity.cpp

@@ -43,7 +43,6 @@ void SleepActivity::renderCustomSleepScreen() const {
   if (dir && dir.isDirectory()) {
     sleepDir = "/.sleep";
   } else {
-    if (dir) dir.close();
     dir = Storage.open("/sleep");
     if (dir && dir.isDirectory()) {
       sleepDir = "/sleep";
@@ -56,29 +55,24 @@ void SleepActivity::renderCustomSleepScreen() const {
     // collect all valid BMP files
     for (auto file = dir.openNextFile(); file; file = dir.openNextFile()) {
       if (file.isDirectory()) {
-        file.close();
         continue;
       }
       file.getName(name, sizeof(name));
       auto filename = std::string(name);
       if (filename[0] == '.') {
-        file.close();
         continue;
       }
 
       if (!FsHelpers::hasBmpExtension(filename)) {
         LOG_DBG("SLP", "Skipping non-.bmp file name: %s", name);
-        file.close();
         continue;
       }
       Bitmap bitmap(file);
       if (bitmap.parseHeaders() != BmpReaderError::Ok) {
         LOG_DBG("SLP", "Skipping invalid BMP file: %s", name);
-        file.close();
         continue;
       }
       files.emplace_back(filename);
-      file.close();
     }
     const auto numFiles = files.size();
     if (numFiles > 0) {
@@ -98,16 +92,11 @@ void SleepActivity::renderCustomSleepScreen() const {
         Bitmap bitmap(file, true);
         if (bitmap.parseHeaders() == BmpReaderError::Ok) {
           renderBitmapSleepScreen(bitmap);
-          file.close();
-          dir.close();
           return;
         }
-        file.close();
       }
     }
   }
-  if (dir) dir.close();
-
   // 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.
   FsFile file;
@@ -116,10 +105,8 @@ void SleepActivity::renderCustomSleepScreen() const {
     if (bitmap.parseHeaders() == BmpReaderError::Ok) {
       LOG_DBG("SLP", "Loading: /sleep.bmp");
       renderBitmapSleepScreen(bitmap);
-      file.close();
       return;
     }
-    file.close();
   }
 
   renderDefaultSleepScreen();
@@ -286,10 +273,8 @@ void SleepActivity::renderCoverSleepScreen() const {
     if (bitmap.parseHeaders() == BmpReaderError::Ok) {
       LOG_DBG("SLP", "Rendering sleep cover: %s", coverBmpPath.c_str());
       renderBitmapSleepScreen(bitmap);
-      file.close();
       return;
     }
-    file.close();
   }
 
   return (this->*renderNoCoverSleepScreen)();

src/activities/home/FileBrowserActivity.cpp

@@ -75,7 +75,6 @@ void FileBrowserActivity::loadFiles() {
 
   auto root = Storage.open(basepath.c_str());
   if (!root || !root.isDirectory()) {
-    if (root) root.close();
     return;
   }
 
@@ -85,7 +84,6 @@ void FileBrowserActivity::loadFiles() {
   for (auto file = root.openNextFile(); file; file = root.openNextFile()) {
     file.getName(name, sizeof(name));
     if ((!SETTINGS.showHiddenFiles && name[0] == '.') || strcmp(name, "System Volume Information") == 0) {
-      file.close();
       continue;
     }
 
@@ -99,9 +97,7 @@ void FileBrowserActivity::loadFiles() {
         files.emplace_back(filename);
       }
     }
-    file.close();
   }
-  root.close();
   sortFileList(files);
 }
 
@@ -115,7 +111,6 @@ void FileBrowserActivity::onEnter() {
     basepath = "/";
     loadFiles();
   } else if (!root.isDirectory()) {
-    root.close();
     lockLongPressBack = mappedInput.isPressed(MappedInputManager::Button::Back);
 
     const std::string oldPath = basepath;
@@ -126,7 +121,6 @@ void FileBrowserActivity::onEnter() {
     const std::string fileName = oldPath.substr(pos + 1);
     selectorIndex = findEntry(fileName);
   } else {
-    root.close();
     loadFiles();
   }
 

src/activities/reader/EpubReaderActivity.cpp

@@ -69,7 +69,6 @@ void EpubReaderActivity::onEnter() {
     if (dataSize == 6) {
       cachedChapterTotalPageCount = data[4] + (data[5] << 8);
     }
-    f.close();
   }
   // We may want a better condition to detect if we are opening for the first time.
   // This will trigger if the book is re-opened at Chapter 0.
@@ -696,7 +695,6 @@ void EpubReaderActivity::saveProgress(int spineIndex, int currentPage, int pageC
     data[4] = pageCount & 0xFF;
     data[5] = (pageCount >> 8) & 0xFF;
     f.write(data, 6);
-    f.close();
     LOG_DBG("ERS", "Progress saved: Chapter %d, Page %d", spineIndex, currentPage);
   } else {
     LOG_ERR("ERS", "Could not save progress!");

src/activities/reader/TxtReaderActivity.cpp

@@ -405,7 +405,6 @@ void TxtReaderActivity::saveProgress() const {
     data[2] = 0;
     data[3] = 0;
     f.write(data, 4);
-    f.close();
   }
 }
 
@@ -423,7 +422,6 @@ void TxtReaderActivity::loadProgress() {
       }
       LOG_DBG("TRS", "Loaded progress: page %d/%d", currentPage, totalPages);
     }
-    f.close();
   }
 }
 
@@ -452,7 +450,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, magic);
   if (magic != CACHE_MAGIC) {
     LOG_DBG("TRS", "Cache magic mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -460,7 +457,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, version);
   if (version != CACHE_VERSION) {
     LOG_DBG("TRS", "Cache version mismatch (%d != %d), rebuilding", version, CACHE_VERSION);
-    f.close();
     return false;
   }
 
@@ -468,7 +464,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, fileSize);
   if (fileSize != txt->getFileSize()) {
     LOG_DBG("TRS", "Cache file size mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -476,7 +471,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, cachedWidth);
   if (cachedWidth != viewportWidth) {
     LOG_DBG("TRS", "Cache viewport width mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -484,7 +478,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, cachedLines);
   if (cachedLines != linesPerPage) {
     LOG_DBG("TRS", "Cache lines per page mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -492,7 +485,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, fontId);
   if (fontId != cachedFontId) {
     LOG_DBG("TRS", "Cache font ID mismatch (%d != %d), rebuilding", fontId, cachedFontId);
-    f.close();
     return false;
   }
 
@@ -500,7 +492,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, margin);
   if (margin != cachedScreenMargin) {
     LOG_DBG("TRS", "Cache screen margin mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -508,7 +499,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
   serialization::readPod(f, alignment);
   if (alignment != cachedParagraphAlignment) {
     LOG_DBG("TRS", "Cache paragraph alignment mismatch, rebuilding");
-    f.close();
     return false;
   }
 
@@ -525,7 +515,6 @@ bool TxtReaderActivity::loadPageIndexCache() {
     pageOffsets.push_back(offset);
   }
 
-  f.close();
   totalPages = pageOffsets.size();
   LOG_DBG("TRS", "Loaded page index cache: %d pages", totalPages);
   return true;
@@ -555,6 +544,5 @@ void TxtReaderActivity::savePageIndexCache() const {
     serialization::writePod(f, static_cast<uint32_t>(offset));
   }
 
-  f.close();
   LOG_DBG("TRS", "Saved page index cache: %d pages", totalPages);
 }

src/components/themes/BaseTheme.cpp

@@ -422,7 +422,6 @@ void BaseTheme::drawRecentBookCover(GfxRenderer& renderer, Rect rect, const std:
           bookWidth = rect.width / 2;  // Fallback
         }
       }
-      file.close();
     }
   }
 
@@ -476,7 +475,6 @@ void BaseTheme::drawRecentBookCover(GfxRenderer& renderer, Rect rect, const std:
             renderer.drawRect(bookX + 2, bookY + 2, bookWidth - 4, bookHeight - 4);
           }
         }
-        file.close();
       }
     }
 

src/network/CrossPointWebServer.cpp

@@ -193,6 +193,7 @@ void CrossPointWebServer::begin() {
 }
 
 void CrossPointWebServer::abortWsUpload(const char* tag) {
+  // Explicit close() required: file-scope global persists beyond function scope
   wsUploadFile.close();
   String filePath = wsUploadPath;
   if (!filePath.endsWith("/")) filePath += "/";
@@ -1342,6 +1343,7 @@ void CrossPointWebServer::onWebSocketEvent(uint8_t num, WStype_t type, uint8_t*
 
           // Zero-byte upload: complete immediately without waiting for BIN frames
           if (wsUploadSize == 0) {
+            // Explicit close() required: file-scope global persists beyond function scope
             wsUploadFile.close();
             wsLastCompleteName = wsUploadFileName;
             wsLastCompleteSize = 0;
@@ -1397,6 +1399,7 @@ void CrossPointWebServer::onWebSocketEvent(uint8_t num, WStype_t type, uint8_t*
 
       // Check if upload complete
       if (wsUploadReceived >= wsUploadSize) {
+        // Explicit close() required: file-scope global persists beyond function scope
         wsUploadFile.close();
         wsUploadInProgress = false;
         wsUploadClientNum = 255;

src/util/ScreenshotUtil.cpp

@@ -70,6 +70,7 @@ bool ScreenshotUtil::saveFramebufferAsBmp(const char* filename, const uint8_t* f
   }
 
   if (write_error) {
+    // Explicitly close() file before calling Storage.remove()
     file.close();
     Storage.remove(filename);
     return false;
@@ -80,6 +81,7 @@ bool ScreenshotUtil::saveFramebufferAsBmp(const char* filename, const uint8_t* f
   constexpr size_t kMaxRowSize = 68;
   if (rowSizePadded > kMaxRowSize) {
     LOG_ERR("SCR", "Row size %u exceeds buffer capacity", rowSizePadded);
+    // Explicitly close() file before calling Storage.remove()
     file.close();
     Storage.remove(filename);
     return false;
@@ -106,6 +108,7 @@ bool ScreenshotUtil::saveFramebufferAsBmp(const char* filename, const uint8_t* f
     memset(rowBuffer, 0, rowSizePadded);  // Clear the buffer for the next row
   }
 
+  // Explicitly close() file before calling Storage.remove()
   file.close();
 
   if (write_error) {