feat: Add dictionary word lookup feature with cached index

Implements StarDict-based dictionary lookup from the reader menu,
adapted from upstream PR #857 with /.dictionary/ folder path,
std::vector compatibility (PR #802), HTML definition rendering,
orientation-aware button hints, side button hints with CCW text
rotation, sparse index caching to SD card, pronunciation line
filtering, and reorganized reader menu with bookmark stubs.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/Epub/Epub/Page.h

@@ -28,6 +28,7 @@ class PageLine final : public PageElement {
  public:
   PageLine(std::shared_ptr<TextBlock> block, const int16_t xPos, const int16_t yPos)
       : PageElement(xPos, yPos), block(std::move(block)) {}
+  const std::shared_ptr<TextBlock>& getBlock() const { return block; }
   void render(GfxRenderer& renderer, int fontId, int xOffset, int yOffset) override;
   bool serialize(FsFile& file) override;
   static std::unique_ptr<PageLine> deserialize(FsFile& file);

lib/Epub/Epub/blocks/TextBlock.h

@@ -27,6 +27,9 @@ class TextBlock final : public Block {
   ~TextBlock() override = default;
   void setBlockStyle(const BlockStyle& blockStyle) { this->blockStyle = blockStyle; }
   const BlockStyle& getBlockStyle() const { return blockStyle; }
+  const std::vector<std::string>& getWords() const { return words; }
+  const std::vector<uint16_t>& getWordXpos() const { return wordXpos; }
+  const std::vector<EpdFontFamily::Style>& getWordStyles() const { return wordStyles; }
   bool isEmpty() override { return words.empty(); }
   void layout(GfxRenderer& renderer) override {};
   // given a renderer works out where to break the words into lines

lib/GfxRenderer/GfxRenderer.cpp

@@ -905,6 +905,92 @@ void GfxRenderer::drawTextRotated90CW(const int fontId, const int x, const int y
   }
 }
 
+void GfxRenderer::drawTextRotated90CCW(const int fontId, const int x, const int y, const char* text, const bool black,
+                                       const EpdFontFamily::Style style) const {
+  // Cannot draw a NULL / empty string
+  if (text == nullptr || *text == '\0') {
+    return;
+  }
+
+  if (fontMap.count(fontId) == 0) {
+    Serial.printf("[%lu] [GFX] Font %d not found\n", millis(), fontId);
+    return;
+  }
+  const auto font = fontMap.at(fontId);
+
+  // No printable characters
+  if (!font.hasPrintableChars(text, style)) {
+    return;
+  }
+
+  // For 90° counter-clockwise rotation:
+  // Mirror of CW: glyphY maps to -X direction, glyphX maps to +Y direction
+  // Text reads from top to bottom
+
+  const int advanceY = font.getData(style)->advanceY;
+  const int ascender = font.getData(style)->ascender;
+
+  int yPos = y;  // Current Y position (increases as we draw characters)
+
+  uint32_t cp;
+  while ((cp = utf8NextCodepoint(reinterpret_cast<const uint8_t**>(&text)))) {
+    const EpdGlyph* glyph = font.getGlyph(cp, style);
+    if (!glyph) {
+      glyph = font.getGlyph(REPLACEMENT_GLYPH, style);
+    }
+    if (!glyph) {
+      continue;
+    }
+
+    const int is2Bit = font.getData(style)->is2Bit;
+    const uint32_t offset = glyph->dataOffset;
+    const uint8_t width = glyph->width;
+    const uint8_t height = glyph->height;
+    const int left = glyph->left;
+    const int top = glyph->top;
+
+    const uint8_t* bitmap = &font.getData(style)->bitmap[offset];
+
+    if (bitmap != nullptr) {
+      for (int glyphY = 0; glyphY < height; glyphY++) {
+        for (int glyphX = 0; glyphX < width; glyphX++) {
+          const int pixelPosition = glyphY * width + glyphX;
+
+          // 90° counter-clockwise rotation transformation:
+          // screenX = mirrored CW X (right-to-left within advanceY span)
+          // screenY = yPos + (left + glyphX) (downward)
+          const int screenX = x + advanceY - 1 - (ascender - top + glyphY);
+          const int screenY = yPos + left + glyphX;
+
+          if (is2Bit) {
+            const uint8_t byte = bitmap[pixelPosition / 4];
+            const uint8_t bit_index = (3 - pixelPosition % 4) * 2;
+            const uint8_t bmpVal = 3 - (byte >> bit_index) & 0x3;
+
+            if (renderMode == BW && bmpVal < 3) {
+              drawPixel(screenX, screenY, black);
+            } else if (renderMode == GRAYSCALE_MSB && (bmpVal == 1 || bmpVal == 2)) {
+              drawPixel(screenX, screenY, false);
+            } else if (renderMode == GRAYSCALE_LSB && bmpVal == 1) {
+              drawPixel(screenX, screenY, false);
+            }
+          } else {
+            const uint8_t byte = bitmap[pixelPosition / 8];
+            const uint8_t bit_index = 7 - (pixelPosition % 8);
+
+            if ((byte >> bit_index) & 1) {
+              drawPixel(screenX, screenY, black);
+            }
+          }
+        }
+      }
+    }
+
+    // Move to next character position (going down, so increase Y)
+    yPos += glyph->advanceX;
+  }
+}
+
 uint8_t* GfxRenderer::getFrameBuffer() const { return frameBuffer; }
 
 size_t GfxRenderer::getBufferSize() { return HalDisplay::BUFFER_SIZE; }

lib/GfxRenderer/GfxRenderer.h

@@ -111,9 +111,11 @@ class GfxRenderer {
   std::string truncatedText(int fontId, const char* text, int maxWidth,
                             EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
 
-  // Helper for drawing rotated text (90 degrees clockwise, for side buttons)
+  // Helpers for drawing rotated text (for side buttons)
   void drawTextRotated90CW(int fontId, int x, int y, const char* text, bool black = true,
                            EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
+  void drawTextRotated90CCW(int fontId, int x, int y, const char* text, bool black = true,
+                            EpdFontFamily::Style style = EpdFontFamily::REGULAR) const;
   int getTextHeight(int fontId) const;
 
   // Grayscale functions

src/activities/reader/DictionaryDefinitionActivity.cpp

@@ -0,0 +1,537 @@
+#include "DictionaryDefinitionActivity.h"
+
+#include <GfxRenderer.h>
+
+#include <algorithm>
+#include <cctype>
+#include <cstdlib>
+
+#include "CrossPointSettings.h"
+#include "MappedInputManager.h"
+#include "components/UITheme.h"
+#include "fontIds.h"
+
+void DictionaryDefinitionActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<DictionaryDefinitionActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void DictionaryDefinitionActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      renderScreen();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void DictionaryDefinitionActivity::onEnter() {
+  Activity::onEnter();
+  renderingMutex = xSemaphoreCreateMutex();
+  wrapText();
+  updateRequired = true;
+  xTaskCreate(&DictionaryDefinitionActivity::taskTrampoline, "DictDefTask", 4096, this, 1, &displayTaskHandle);
+}
+
+void DictionaryDefinitionActivity::onExit() {
+  Activity::onExit();
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+// ---------------------------------------------------------------------------
+// Check if a Unicode codepoint is likely renderable by the e-ink bitmap font.
+// Keeps Latin text, combining marks, common punctuation, currency, and letterlike symbols.
+// Skips IPA extensions, Greek, Cyrillic, Arabic, CJK, and other non-Latin scripts.
+// ---------------------------------------------------------------------------
+bool DictionaryDefinitionActivity::isRenderableCodepoint(uint32_t cp) {
+  if (cp <= 0x024F) return true;                       // Basic Latin + Latin Extended-A/B
+  if (cp >= 0x0300 && cp <= 0x036F) return true;       // Combining Diacritical Marks
+  if (cp >= 0x2000 && cp <= 0x206F) return true;       // General Punctuation
+  if (cp >= 0x20A0 && cp <= 0x20CF) return true;       // Currency Symbols
+  if (cp >= 0x2100 && cp <= 0x214F) return true;       // Letterlike Symbols
+  if (cp >= 0x2190 && cp <= 0x21FF) return true;       // Arrows
+  return false;
+}
+
+// ---------------------------------------------------------------------------
+// HTML entity decoder
+// ---------------------------------------------------------------------------
+std::string DictionaryDefinitionActivity::decodeEntity(const std::string& entity) {
+  // Named entities
+  if (entity == "amp") return "&";
+  if (entity == "lt") return "<";
+  if (entity == "gt") return ">";
+  if (entity == "quot") return "\"";
+  if (entity == "apos") return "'";
+  if (entity == "nbsp" || entity == "thinsp" || entity == "ensp" || entity == "emsp") return " ";
+  if (entity == "ndash") return "\xE2\x80\x93";  // U+2013
+  if (entity == "mdash") return "\xE2\x80\x94";   // U+2014
+  if (entity == "lsquo") return "\xE2\x80\x98";
+  if (entity == "rsquo") return "\xE2\x80\x99";
+  if (entity == "ldquo") return "\xE2\x80\x9C";
+  if (entity == "rdquo") return "\xE2\x80\x9D";
+  if (entity == "hellip") return "\xE2\x80\xA6";
+  if (entity == "lrm" || entity == "rlm" || entity == "zwj" || entity == "zwnj") return "";
+
+  // Numeric entities: &#123; or &#x1F;
+  if (!entity.empty() && entity[0] == '#') {
+    unsigned long cp = 0;
+    if (entity.size() > 1 && (entity[1] == 'x' || entity[1] == 'X')) {
+      cp = std::strtoul(entity.c_str() + 2, nullptr, 16);
+    } else {
+      cp = std::strtoul(entity.c_str() + 1, nullptr, 10);
+    }
+    if (cp > 0 && cp < 0x80) {
+      return std::string(1, static_cast<char>(cp));
+    }
+    if (cp >= 0x80 && cp < 0x800) {
+      char buf[3] = {static_cast<char>(0xC0 | (cp >> 6)), static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
+      return std::string(buf, 2);
+    }
+    if (cp >= 0x800 && cp < 0x10000) {
+      char buf[4] = {static_cast<char>(0xE0 | (cp >> 12)), static_cast<char>(0x80 | ((cp >> 6) & 0x3F)),
+                     static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
+      return std::string(buf, 3);
+    }
+    if (cp >= 0x10000 && cp < 0x110000) {
+      char buf[5] = {static_cast<char>(0xF0 | (cp >> 18)), static_cast<char>(0x80 | ((cp >> 12) & 0x3F)),
+                     static_cast<char>(0x80 | ((cp >> 6) & 0x3F)), static_cast<char>(0x80 | (cp & 0x3F)), '\0'};
+      return std::string(buf, 4);
+    }
+  }
+
+  return "";  // unknown entity — drop it
+}
+
+// ---------------------------------------------------------------------------
+// HTML → TextAtom list
+// ---------------------------------------------------------------------------
+std::vector<DictionaryDefinitionActivity::TextAtom> DictionaryDefinitionActivity::parseHtml(const std::string& html) {
+  std::vector<TextAtom> atoms;
+
+  bool isBold = false;
+  bool isItalic = false;
+  bool inSvg = false;
+  int svgDepth = 0;
+  std::vector<ListState> listStack;
+  std::string currentWord;
+
+  auto currentStyle = [&]() -> EpdFontFamily::Style {
+    if (isBold && isItalic) return EpdFontFamily::BOLD_ITALIC;
+    if (isBold) return EpdFontFamily::BOLD;
+    if (isItalic) return EpdFontFamily::ITALIC;
+    return EpdFontFamily::REGULAR;
+  };
+
+  auto flushWord = [&]() {
+    if (!currentWord.empty() && !inSvg) {
+      atoms.push_back({currentWord, currentStyle(), false, 0});
+      currentWord.clear();
+    }
+  };
+
+  auto indentPx = [&]() -> int {
+    // 15 pixels per nesting level (the first level has no extra indent)
+    int depth = static_cast<int>(listStack.size());
+    return (depth > 1) ? (depth - 1) * 15 : 0;
+  };
+
+  // Skip any leading non-HTML text (e.g. pronunciation guides like "/ˈsɪm.pəl/, /ˈsɪmpəl/")
+  // that appears before the first tag in sametypesequence=h entries.
+  size_t i = 0;
+  {
+    size_t firstTag = html.find('<');
+    if (firstTag != std::string::npos) i = firstTag;
+  }
+
+  while (i < html.size()) {
+    // ------- HTML tag -------
+    if (html[i] == '<') {
+      flushWord();
+
+      size_t tagEnd = html.find('>', i);
+      if (tagEnd == std::string::npos) break;
+
+      std::string tagContent = html.substr(i + 1, tagEnd - i - 1);
+
+      // Extract tag name: first token, lowercased, trailing '/' stripped.
+      size_t space = tagContent.find(' ');
+      std::string tagName = (space != std::string::npos) ? tagContent.substr(0, space) : tagContent;
+      for (auto& c : tagName) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
+      if (!tagName.empty() && tagName.back() == '/') tagName.pop_back();
+
+      // --- SVG handling (skip all content inside <svg>…</svg>) ---
+      if (tagName == "svg") {
+        inSvg = true;
+        svgDepth = 1;
+      } else if (inSvg) {
+        if (tagName == "svg") {
+          svgDepth++;
+        } else if (tagName == "/svg") {
+          svgDepth--;
+          if (svgDepth <= 0) inSvg = false;
+        }
+      }
+
+      if (!inSvg) {
+        // --- Inline style tags ---
+        if (tagName == "b" || tagName == "strong") {
+          isBold = true;
+        } else if (tagName == "/b" || tagName == "/strong") {
+          isBold = false;
+        } else if (tagName == "i" || tagName == "em") {
+          isItalic = true;
+        } else if (tagName == "/i" || tagName == "/em") {
+          isItalic = false;
+
+          // --- Block-level tags → newlines ---
+        } else if (tagName == "p" || tagName == "h1" || tagName == "h2" || tagName == "h3" || tagName == "h4") {
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
+          // Headings get bold style applied to following text
+          if (tagName != "p") isBold = true;
+        } else if (tagName == "/p" || tagName == "/h1" || tagName == "/h2" || tagName == "/h3" || tagName == "/h4") {
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
+          isBold = false;
+        } else if (tagName == "br") {
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
+
+          // --- Separator between definition entries ---
+        } else if (tagName == "/html") {
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, 0});
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, 0});  // extra blank line
+          isBold = false;
+          isItalic = false;
+          // Skip any raw text between </html> and the next tag — this is where
+          // pronunciation guides (e.g. /ˈsɪmpəl/, /ksɛpt/) live in this dictionary.
+          size_t nextTag = html.find('<', tagEnd + 1);
+          i = (nextTag != std::string::npos) ? nextTag : html.size();
+          continue;
+
+          // --- Lists ---
+        } else if (tagName == "ol") {
+          bool alpha = tagContent.find("lower-alpha") != std::string::npos;
+          listStack.push_back({0, alpha});
+        } else if (tagName == "ul") {
+          listStack.push_back({0, false});
+        } else if (tagName == "/ol" || tagName == "/ul") {
+          if (!listStack.empty()) listStack.pop_back();
+        } else if (tagName == "li") {
+          atoms.push_back({"", EpdFontFamily::REGULAR, true, indentPx()});
+          if (!listStack.empty()) {
+            auto& ls = listStack.back();
+            ls.counter++;
+            std::string marker;
+            if (ls.isAlpha && ls.counter >= 1 && ls.counter <= 26) {
+              marker = std::string(1, static_cast<char>('a' + ls.counter - 1)) + ". ";
+            } else if (ls.isAlpha) {
+              marker = std::to_string(ls.counter) + ". ";
+            } else {
+              marker = std::to_string(ls.counter) + ". ";
+            }
+            atoms.push_back({marker, EpdFontFamily::REGULAR, false, 0});
+          } else {
+            // Unordered list or bare <li>
+            atoms.push_back({"\xE2\x80\xA2 ", EpdFontFamily::REGULAR, false, 0});
+          }
+        }
+        // All other tags (span, div, code, sup, sub, table, etc.) are silently ignored;
+        // their text content will still be emitted.
+      }
+
+      i = tagEnd + 1;
+      continue;
+    }
+
+    // Skip content inside SVG
+    if (inSvg) {
+      i++;
+      continue;
+    }
+
+    // ------- HTML entity -------
+    if (html[i] == '&') {
+      size_t semicolon = html.find(';', i);
+      if (semicolon != std::string::npos && semicolon - i < 16) {
+        std::string entity = html.substr(i + 1, semicolon - i - 1);
+        std::string decoded = decodeEntity(entity);
+        if (!decoded.empty()) {
+          // Treat decoded chars like normal text (could be space etc.)
+          for (char dc : decoded) {
+            if (dc == ' ') {
+              flushWord();
+            } else {
+              currentWord += dc;
+            }
+          }
+        }
+        i = semicolon + 1;
+        continue;
+      }
+      // Not a valid entity — emit '&' literally
+      currentWord += '&';
+      i++;
+      continue;
+    }
+
+    // ------- IPA pronunciation (skip /…/ and […] containing non-ASCII) -------
+    if (html[i] == '/' || html[i] == '[') {
+      char closeDelim = (html[i] == '/') ? '/' : ']';
+      size_t end = html.find(closeDelim, i + 1);
+      if (end != std::string::npos && end - i < 80) {
+        bool hasNonAscii = false;
+        for (size_t j = i + 1; j < end; j++) {
+          if (static_cast<unsigned char>(html[j]) > 127) {
+            hasNonAscii = true;
+            break;
+          }
+        }
+        if (hasNonAscii) {
+          flushWord();
+          i = end + 1;  // skip entire IPA section including delimiters
+          continue;
+        }
+      }
+      // Not IPA — fall through to treat as regular character
+    }
+
+    // ------- Whitespace -------
+    if (html[i] == ' ' || html[i] == '\t' || html[i] == '\n' || html[i] == '\r') {
+      flushWord();
+      i++;
+      continue;
+    }
+
+    // ------- Regular character (with non-renderable character filter) -------
+    {
+      unsigned char byte = static_cast<unsigned char>(html[i]);
+      if (byte < 0x80) {
+        // ASCII — always renderable
+        currentWord += html[i];
+        i++;
+      } else {
+        // Multi-byte UTF-8: decode codepoint and check if renderable
+        int seqLen = 1;
+        uint32_t cp = 0;
+        if ((byte & 0xE0) == 0xC0) {
+          seqLen = 2;
+          cp = byte & 0x1F;
+        } else if ((byte & 0xF0) == 0xE0) {
+          seqLen = 3;
+          cp = byte & 0x0F;
+        } else if ((byte & 0xF8) == 0xF0) {
+          seqLen = 4;
+          cp = byte & 0x07;
+        } else {
+          i++;
+          continue;
+        }  // invalid start byte
+
+        if (i + static_cast<size_t>(seqLen) > html.size()) {
+          i++;
+          continue;
+        }
+
+        bool valid = true;
+        for (int j = 1; j < seqLen; j++) {
+          unsigned char cb = static_cast<unsigned char>(html[i + j]);
+          if ((cb & 0xC0) != 0x80) {
+            valid = false;
+            break;
+          }
+          cp = (cp << 6) | (cb & 0x3F);
+        }
+
+        if (valid && isRenderableCodepoint(cp)) {
+          for (int j = 0; j < seqLen; j++) {
+            currentWord += html[i + j];
+          }
+        }
+        // else: silently skip non-renderable character
+
+        i += valid ? seqLen : 1;
+      }
+    }
+  }
+
+  flushWord();
+  return atoms;
+}
+
+// ---------------------------------------------------------------------------
+// Word-wrap the parsed HTML atoms into positioned line segments
+// ---------------------------------------------------------------------------
+void DictionaryDefinitionActivity::wrapText() {
+  wrappedLines.clear();
+
+  const bool landscape = orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||
+                         orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW;
+  const int screenWidth = renderer.getScreenWidth();
+  const int lineHeight = renderer.getLineHeight(readerFontId);
+  const int sidePadding = landscape ? 50 : 20;
+  constexpr int topArea = 50;
+  constexpr int bottomArea = 50;
+  const int maxWidth = screenWidth - 2 * sidePadding;
+  const int spaceWidth = renderer.getSpaceWidth(readerFontId);
+
+  linesPerPage = (renderer.getScreenHeight() - topArea - bottomArea) / lineHeight;
+  if (linesPerPage < 1) linesPerPage = 1;
+
+  auto atoms = parseHtml(definition);
+
+  std::vector<Segment> currentLine;
+  int currentX = 0;
+  int baseIndent = 0;  // indent for continuation lines within the same block
+
+  for (const auto& atom : atoms) {
+    // ---- Newline directive ----
+    if (atom.isNewline) {
+      // Collapse multiple consecutive blank lines
+      if (currentLine.empty() && !wrappedLines.empty() && wrappedLines.back().empty()) {
+        // Already have a blank line; update indent but don't push another
+        baseIndent = atom.indent;
+        currentX = baseIndent;
+        continue;
+      }
+      wrappedLines.push_back(std::move(currentLine));
+      currentLine.clear();
+      baseIndent = atom.indent;
+      currentX = baseIndent;
+      continue;
+    }
+
+    // ---- Text word ----
+    int wordWidth = renderer.getTextWidth(readerFontId, atom.text.c_str(), atom.style);
+    int gap = (currentX > baseIndent) ? spaceWidth : 0;
+
+    // Wrap if this word won't fit
+    if (currentX + gap + wordWidth > maxWidth && currentX > baseIndent) {
+      wrappedLines.push_back(std::move(currentLine));
+      currentLine.clear();
+      currentX = baseIndent;
+      gap = 0;
+    }
+
+    int16_t x = static_cast<int16_t>(currentX + gap);
+    currentLine.push_back({atom.text, x, atom.style});
+    currentX = x + wordWidth;
+  }
+
+  // Flush last line
+  if (!currentLine.empty()) {
+    wrappedLines.push_back(std::move(currentLine));
+  }
+
+  totalPages = (static_cast<int>(wrappedLines.size()) + linesPerPage - 1) / linesPerPage;
+  if (totalPages < 1) totalPages = 1;
+}
+
+void DictionaryDefinitionActivity::loop() {
+  const bool prevPage = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
+                        mappedInput.wasReleased(MappedInputManager::Button::Left);
+  const bool nextPage = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                        mappedInput.wasReleased(MappedInputManager::Button::Right);
+
+  if (prevPage && currentPage > 0) {
+    currentPage--;
+    updateRequired = true;
+  }
+
+  if (nextPage && currentPage < totalPages - 1) {
+    currentPage++;
+    updateRequired = true;
+  }
+
+  if (mappedInput.wasReleased(MappedInputManager::Button::Back) ||
+      mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+    onBack();
+    return;
+  }
+}
+
+void DictionaryDefinitionActivity::renderScreen() {
+  renderer.clearScreen();
+
+  const bool landscape = orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||
+                         orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW;
+  const int sidePadding = landscape ? 50 : 20;
+  constexpr int titleY = 10;
+  const int lineHeight = renderer.getLineHeight(readerFontId);
+  constexpr int bodyStartY = 50;
+
+  // Title: the word in bold (UI font)
+  renderer.drawText(UI_12_FONT_ID, sidePadding, titleY, headword.c_str(), true, EpdFontFamily::BOLD);
+
+  // Separator line
+  renderer.drawLine(sidePadding, 40, renderer.getScreenWidth() - sidePadding, 40);
+
+  // Body: styled definition lines
+  int startLine = currentPage * linesPerPage;
+  for (int i = 0; i < linesPerPage && (startLine + i) < static_cast<int>(wrappedLines.size()); i++) {
+    int y = bodyStartY + i * lineHeight;
+    const auto& line = wrappedLines[startLine + i];
+    for (const auto& seg : line) {
+      renderer.drawText(readerFontId, sidePadding + seg.x, y, seg.text.c_str(), true, seg.style);
+    }
+  }
+
+  // Pagination indicator (bottom right)
+  if (totalPages > 1) {
+    std::string pageInfo = std::to_string(currentPage + 1) + "/" + std::to_string(totalPages);
+    int textWidth = renderer.getTextWidth(SMALL_FONT_ID, pageInfo.c_str());
+    renderer.drawText(SMALL_FONT_ID, renderer.getScreenWidth() - sidePadding - textWidth,
+                      renderer.getScreenHeight() - 50, pageInfo.c_str());
+  }
+
+  // Button hints (bottom face buttons — hide Confirm stub like Home Screen)
+  const auto labels = mappedInput.mapLabels("\xC2\xAB Back", "", "\xC2\xAB Page", "Page \xC2\xBB");
+  GUI.drawButtonHints(renderer, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+
+  // Side button hints (drawn in portrait coordinates for correct placement)
+  {
+    const auto origOrientation = renderer.getOrientation();
+    renderer.setOrientation(GfxRenderer::Orientation::Portrait);
+    const int portW = renderer.getScreenWidth();
+
+    constexpr int sideButtonWidth = 30;
+    constexpr int sideButtonHeight = 78;
+    constexpr int sideButtonGap = 5;
+    constexpr int sideTopY = 345;
+    constexpr int cornerRadius = 6;
+    const int sideX = portW - sideButtonWidth;
+    const int sideButtonY[2] = {sideTopY, sideTopY + sideButtonHeight + sideButtonGap};
+    const char* sideLabels[2] = {"\xC2\xAB Page", "Page \xC2\xBB"};
+    const bool useCCW = (orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW);
+
+    for (int i = 0; i < 2; i++) {
+      renderer.fillRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, false);
+      renderer.drawRoundedRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, 1, cornerRadius, true, false,
+                               true, false, true);
+
+      const std::string truncated = renderer.truncatedText(SMALL_FONT_ID, sideLabels[i], sideButtonHeight);
+      const int tw = renderer.getTextWidth(SMALL_FONT_ID, truncated.c_str());
+
+      if (useCCW) {
+        renderer.drawTextRotated90CCW(SMALL_FONT_ID, sideX,
+                                      sideButtonY[i] + (sideButtonHeight - tw) / 2, truncated.c_str());
+      } else {
+        renderer.drawTextRotated90CW(SMALL_FONT_ID, sideX,
+                                     sideButtonY[i] + (sideButtonHeight + tw) / 2, truncated.c_str());
+      }
+    }
+
+    renderer.setOrientation(origOrientation);
+  }
+
+  // Use half refresh when entering the screen for cleaner transition; fast refresh for page turns.
+  renderer.displayBuffer(firstRender ? HalDisplay::HALF_REFRESH : HalDisplay::FAST_REFRESH);
+  firstRender = false;
+}

src/activities/reader/DictionaryDefinitionActivity.h

@@ -0,0 +1,74 @@
+#pragma once
+#include <EpdFontFamily.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <string>
+#include <vector>
+
+#include "../Activity.h"
+
+class DictionaryDefinitionActivity final : public Activity {
+ public:
+  explicit DictionaryDefinitionActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                        const std::string& headword, const std::string& definition, int readerFontId,
+                                        uint8_t orientation, const std::function<void()>& onBack)
+      : Activity("DictionaryDefinition", renderer, mappedInput),
+        headword(headword),
+        definition(definition),
+        readerFontId(readerFontId),
+        orientation(orientation),
+        onBack(onBack) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+
+ private:
+  // A positioned text segment within a wrapped line (pre-calculated x offset and style).
+  struct Segment {
+    std::string text;
+    int16_t x;
+    EpdFontFamily::Style style;
+  };
+
+  // An intermediate token produced by the HTML parser before word-wrapping.
+  struct TextAtom {
+    std::string text;
+    EpdFontFamily::Style style;
+    bool isNewline;
+    int indent;  // pixels to indent the new line (for nested lists)
+  };
+
+  // Tracks ordered/unordered list nesting during HTML parsing.
+  struct ListState {
+    int counter;   // incremented per <li>, 0 = not yet used
+    bool isAlpha;  // true for list-style-type: lower-alpha
+  };
+
+  std::string headword;
+  std::string definition;
+  int readerFontId;
+  uint8_t orientation;
+  const std::function<void()> onBack;
+
+  std::vector<std::vector<Segment>> wrappedLines;
+  int currentPage = 0;
+  int linesPerPage = 0;
+  int totalPages = 0;
+  bool updateRequired = false;
+  bool firstRender = true;
+
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+
+  std::vector<TextAtom> parseHtml(const std::string& html);
+  static std::string decodeEntity(const std::string& entity);
+  static bool isRenderableCodepoint(uint32_t cp);
+  void wrapText();
+  void renderScreen();
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+};

src/activities/reader/DictionaryWordSelectActivity.cpp

@@ -0,0 +1,541 @@
+#include "DictionaryWordSelectActivity.h"
+
+#include <GfxRenderer.h>
+
+#include <algorithm>
+#include <climits>
+
+#include "CrossPointSettings.h"
+#include "MappedInputManager.h"
+#include "components/UITheme.h"
+#include "fontIds.h"
+#include "util/Dictionary.h"
+#include "util/LookupHistory.h"
+
+void DictionaryWordSelectActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<DictionaryWordSelectActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void DictionaryWordSelectActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      renderScreen();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void DictionaryWordSelectActivity::onEnter() {
+  Activity::onEnter();
+  renderingMutex = xSemaphoreCreateMutex();
+  extractWords();
+  mergeHyphenatedWords();
+  if (!rows.empty()) {
+    currentRow = static_cast<int>(rows.size()) / 3;
+    currentWordInRow = 0;
+  }
+  updateRequired = true;
+  xTaskCreate(&DictionaryWordSelectActivity::taskTrampoline, "DictWordSelTask", 4096, this, 1, &displayTaskHandle);
+}
+
+void DictionaryWordSelectActivity::onExit() {
+  Activity::onExit();
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+bool DictionaryWordSelectActivity::isLandscape() const {
+  return orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW ||
+         orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW;
+}
+
+bool DictionaryWordSelectActivity::isInverted() const {
+  return orientation == CrossPointSettings::ORIENTATION::INVERTED;
+}
+
+void DictionaryWordSelectActivity::extractWords() {
+  words.clear();
+  rows.clear();
+
+  for (const auto& element : page->elements) {
+    // PageLine is the only concrete PageElement type, identified by tag
+    const auto* line = static_cast<const PageLine*>(element.get());
+
+    const auto& block = line->getBlock();
+    if (!block) continue;
+
+    const auto& wordList = block->getWords();
+    const auto& xPosList = block->getWordXpos();
+
+    auto wordIt = wordList.begin();
+    auto xIt = xPosList.begin();
+
+    while (wordIt != wordList.end() && xIt != xPosList.end()) {
+      int16_t screenX = line->xPos + static_cast<int16_t>(*xIt) + marginLeft;
+      int16_t screenY = line->yPos + marginTop;
+      int16_t wordWidth = renderer.getTextWidth(fontId, wordIt->c_str());
+
+      words.push_back({*wordIt, screenX, screenY, wordWidth, 0});
+      ++wordIt;
+      ++xIt;
+    }
+  }
+
+  // Group words into rows by Y position
+  if (words.empty()) return;
+
+  int16_t currentY = words[0].screenY;
+  rows.push_back({currentY, {}});
+
+  for (size_t i = 0; i < words.size(); i++) {
+    // Allow small Y tolerance (words on same line may differ by a pixel)
+    if (std::abs(words[i].screenY - currentY) > 2) {
+      currentY = words[i].screenY;
+      rows.push_back({currentY, {}});
+    }
+    words[i].row = static_cast<int16_t>(rows.size() - 1);
+    rows.back().wordIndices.push_back(static_cast<int>(i));
+  }
+}
+
+void DictionaryWordSelectActivity::mergeHyphenatedWords() {
+  for (size_t r = 0; r + 1 < rows.size(); r++) {
+    if (rows[r].wordIndices.empty() || rows[r + 1].wordIndices.empty()) continue;
+
+    int lastWordIdx = rows[r].wordIndices.back();
+    const std::string& lastWord = words[lastWordIdx].text;
+    if (lastWord.empty()) continue;
+
+    // Check if word ends with hyphen (regular '-' or soft hyphen U+00AD: 0xC2 0xAD)
+    bool endsWithHyphen = false;
+    if (lastWord.back() == '-') {
+      endsWithHyphen = true;
+    } else if (lastWord.size() >= 2 && static_cast<uint8_t>(lastWord[lastWord.size() - 2]) == 0xC2 &&
+               static_cast<uint8_t>(lastWord[lastWord.size() - 1]) == 0xAD) {
+      endsWithHyphen = true;
+    }
+
+    if (!endsWithHyphen) continue;
+
+    int nextWordIdx = rows[r + 1].wordIndices.front();
+
+    // Set bidirectional continuation links for highlighting both parts
+    words[lastWordIdx].continuationIndex = nextWordIdx;
+    words[nextWordIdx].continuationOf = lastWordIdx;
+
+    // Build merged lookup text: remove trailing hyphen and combine
+    std::string firstPart = lastWord;
+    if (firstPart.back() == '-') {
+      firstPart.pop_back();
+    } else if (firstPart.size() >= 2 && static_cast<uint8_t>(firstPart[firstPart.size() - 2]) == 0xC2 &&
+               static_cast<uint8_t>(firstPart[firstPart.size() - 1]) == 0xAD) {
+      firstPart.erase(firstPart.size() - 2);
+    }
+    std::string merged = firstPart + words[nextWordIdx].text;
+    words[lastWordIdx].lookupText = merged;
+    words[nextWordIdx].lookupText = merged;
+    words[nextWordIdx].continuationIndex = nextWordIdx;  // self-ref so highlight logic finds the second part
+  }
+
+  // Remove empty rows that may result from merging (e.g., a row whose only word was a continuation)
+  rows.erase(std::remove_if(rows.begin(), rows.end(), [](const Row& r) { return r.wordIndices.empty(); }), rows.end());
+}
+
+void DictionaryWordSelectActivity::loop() {
+  if (words.empty()) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      onBack();
+    }
+    return;
+  }
+
+  bool changed = false;
+  const bool landscape = isLandscape();
+  const bool inverted = isInverted();
+
+  // Button mapping depends on physical orientation:
+  // - Portrait: side Up/Down = row nav, face Left/Right = word nav
+  // - Inverted: same axes but reversed directions (device is flipped 180)
+  // - Landscape: face Left/Right = row nav (swapped), side Up/Down = word nav
+  bool rowPrevPressed, rowNextPressed, wordPrevPressed, wordNextPressed;
+
+  if (landscape && orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW) {
+    rowPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::Left);
+    rowNextPressed = mappedInput.wasReleased(MappedInputManager::Button::Right);
+    wordPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                      mappedInput.wasReleased(MappedInputManager::Button::Down);
+    wordNextPressed = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
+                      mappedInput.wasReleased(MappedInputManager::Button::Up);
+  } else if (landscape) {
+    rowPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::Right);
+    rowNextPressed = mappedInput.wasReleased(MappedInputManager::Button::Left);
+    wordPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
+                      mappedInput.wasReleased(MappedInputManager::Button::Up);
+    wordNextPressed = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                      mappedInput.wasReleased(MappedInputManager::Button::Down);
+  } else if (inverted) {
+    rowPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                     mappedInput.wasReleased(MappedInputManager::Button::Down);
+    rowNextPressed = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
+                     mappedInput.wasReleased(MappedInputManager::Button::Up);
+    wordPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::Right);
+    wordNextPressed = mappedInput.wasReleased(MappedInputManager::Button::Left);
+  } else {
+    // Portrait (default)
+    rowPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::PageBack) ||
+                     mappedInput.wasReleased(MappedInputManager::Button::Up);
+    rowNextPressed = mappedInput.wasReleased(MappedInputManager::Button::PageForward) ||
+                     mappedInput.wasReleased(MappedInputManager::Button::Down);
+    wordPrevPressed = mappedInput.wasReleased(MappedInputManager::Button::Left);
+    wordNextPressed = mappedInput.wasReleased(MappedInputManager::Button::Right);
+  }
+
+  const int rowCount = static_cast<int>(rows.size());
+
+  // Helper: find closest word by X position in a target row
+  auto findClosestWord = [&](int targetRow) {
+    int wordIdx = rows[currentRow].wordIndices[currentWordInRow];
+    int currentCenterX = words[wordIdx].screenX + words[wordIdx].width / 2;
+    int bestMatch = 0;
+    int bestDist = INT_MAX;
+    for (int i = 0; i < static_cast<int>(rows[targetRow].wordIndices.size()); i++) {
+      int idx = rows[targetRow].wordIndices[i];
+      int centerX = words[idx].screenX + words[idx].width / 2;
+      int dist = std::abs(centerX - currentCenterX);
+      if (dist < bestDist) {
+        bestDist = dist;
+        bestMatch = i;
+      }
+    }
+    return bestMatch;
+  };
+
+  // Move to previous row (wrap to bottom)
+  if (rowPrevPressed) {
+    int targetRow = (currentRow > 0) ? currentRow - 1 : rowCount - 1;
+    currentWordInRow = findClosestWord(targetRow);
+    currentRow = targetRow;
+    changed = true;
+  }
+
+  // Move to next row (wrap to top)
+  if (rowNextPressed) {
+    int targetRow = (currentRow < rowCount - 1) ? currentRow + 1 : 0;
+    currentWordInRow = findClosestWord(targetRow);
+    currentRow = targetRow;
+    changed = true;
+  }
+
+  // Move to previous word (wrap to end of previous row)
+  if (wordPrevPressed) {
+    if (currentWordInRow > 0) {
+      currentWordInRow--;
+    } else if (rowCount > 1) {
+      currentRow = (currentRow > 0) ? currentRow - 1 : rowCount - 1;
+      currentWordInRow = static_cast<int>(rows[currentRow].wordIndices.size()) - 1;
+    }
+    changed = true;
+  }
+
+  // Move to next word (wrap to start of next row)
+  if (wordNextPressed) {
+    if (currentWordInRow < static_cast<int>(rows[currentRow].wordIndices.size()) - 1) {
+      currentWordInRow++;
+    } else if (rowCount > 1) {
+      currentRow = (currentRow < rowCount - 1) ? currentRow + 1 : 0;
+      currentWordInRow = 0;
+    }
+    changed = true;
+  }
+
+  if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+    int wordIdx = rows[currentRow].wordIndices[currentWordInRow];
+    const std::string& rawWord = words[wordIdx].lookupText;
+    std::string cleaned = Dictionary::cleanWord(rawWord);
+
+    if (cleaned.empty()) {
+      GUI.drawPopup(renderer, "No word");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      vTaskDelay(1000 / portTICK_PERIOD_MS);
+      updateRequired = true;
+      return;
+    }
+
+    // Show looking up popup, then release mutex so display task can run
+    xSemaphoreTake(renderingMutex, portMAX_DELAY);
+    Rect popupLayout = GUI.drawPopup(renderer, "Looking up...");
+    xSemaphoreGive(renderingMutex);
+
+    bool cancelled = false;
+    std::string definition = Dictionary::lookup(
+        cleaned,
+        [this, &popupLayout](int percent) {
+          xSemaphoreTake(renderingMutex, portMAX_DELAY);
+          GUI.fillPopupProgress(renderer, popupLayout, percent);
+          xSemaphoreGive(renderingMutex);
+        },
+        [this, &cancelled]() -> bool {
+          mappedInput.update();
+          if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+            cancelled = true;
+            return true;
+          }
+          return false;
+        });
+
+    if (cancelled) {
+      updateRequired = true;
+      return;
+    }
+
+    if (definition.empty()) {
+      GUI.drawPopup(renderer, "Not found");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      vTaskDelay(1500 / portTICK_PERIOD_MS);
+      updateRequired = true;
+      return;
+    }
+
+    LookupHistory::addWord(cachePath, cleaned);
+    onLookup(cleaned, definition);
+    return;
+  }
+
+  if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+    onBack();
+    return;
+  }
+
+  if (changed) {
+    updateRequired = true;
+  }
+}
+
+void DictionaryWordSelectActivity::renderScreen() {
+  renderer.clearScreen();
+
+  // Render the page content
+  page->render(renderer, fontId, marginLeft, marginTop);
+
+  if (!words.empty() && currentRow < static_cast<int>(rows.size())) {
+    int wordIdx = rows[currentRow].wordIndices[currentWordInRow];
+    const auto& w = words[wordIdx];
+
+    // Draw inverted highlight behind selected word
+    const int lineHeight = renderer.getLineHeight(fontId);
+    renderer.fillRect(w.screenX - 1, w.screenY - 1, w.width + 2, lineHeight + 2, true);
+    renderer.drawText(fontId, w.screenX, w.screenY, w.text.c_str(), false);
+
+    // Highlight the other half of a hyphenated word (whether selecting first or second part)
+    int otherIdx = (w.continuationOf >= 0) ? w.continuationOf : -1;
+    if (otherIdx < 0 && w.continuationIndex >= 0 && w.continuationIndex != wordIdx) {
+      otherIdx = w.continuationIndex;
+    }
+    if (otherIdx >= 0) {
+      const auto& other = words[otherIdx];
+      renderer.fillRect(other.screenX - 1, other.screenY - 1, other.width + 2, lineHeight + 2, true);
+      renderer.drawText(fontId, other.screenX, other.screenY, other.text.c_str(), false);
+    }
+  }
+
+  drawHints();
+
+  renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+}
+
+void DictionaryWordSelectActivity::drawHints() {
+  // Draw button hints in portrait orientation (matching physical buttons and theme).
+  // Any hint whose area would overlap the selected word highlight is completely skipped,
+  // leaving the page content underneath visible.
+  const auto origOrientation = renderer.getOrientation();
+
+  // Get portrait dimensions for overlap math
+  renderer.setOrientation(GfxRenderer::Orientation::Portrait);
+  const int portW = renderer.getScreenWidth();   // 480 in portrait
+  const int portH = renderer.getScreenHeight();  // 800 in portrait
+  renderer.setOrientation(origOrientation);
+
+  // Bottom button constants (match LyraTheme::drawButtonHints)
+  constexpr int buttonHeight = 40;     // LyraMetrics::values.buttonHintsHeight
+  constexpr int buttonWidth = 80;
+  constexpr int cornerRadius = 6;
+  constexpr int textYOffset = 7;
+  constexpr int smallButtonHeight = 15;
+  constexpr int buttonPositions[] = {58, 146, 254, 342};
+
+  // Side button constants (match LyraTheme::drawSideButtonHints)
+  constexpr int sideButtonWidth = 30;   // LyraMetrics::values.sideButtonHintsWidth
+  constexpr int sideButtonHeight = 78;
+  constexpr int sideButtonGap = 5;
+  constexpr int sideTopY = 345;         // topHintButtonY
+  const int sideX = portW - sideButtonWidth;
+  const int sideButtonY[2] = {sideTopY, sideTopY + sideButtonHeight + sideButtonGap};
+
+  // Labels for face and side buttons depend on orientation,
+  // because the physical-to-logical mapping rotates with the screen.
+  const char* facePrev;   // label for physical Left face button
+  const char* faceNext;   // label for physical Right face button
+  const char* sideTop;    // label for physical top side button (PageBack)
+  const char* sideBottom; // label for physical bottom side button (PageForward)
+
+  const bool landscape = isLandscape();
+  const bool inverted = isInverted();
+
+  if (landscape && orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CW) {
+    facePrev = "Line Up";    faceNext = "Line Dn";
+    sideTop = "Word \xC2\xBB";   sideBottom = "\xC2\xAB Word";
+  } else if (landscape) {  // LANDSCAPE_CCW
+    facePrev = "Line Dn";    faceNext = "Line Up";
+    sideTop = "\xC2\xAB Word";   sideBottom = "Word \xC2\xBB";
+  } else if (inverted) {
+    facePrev = "Word \xC2\xBB";  faceNext = "\xC2\xAB Word";
+    sideTop = "Line Dn";     sideBottom = "Line Up";
+  } else {  // Portrait (default)
+    facePrev = "\xC2\xAB Word";  faceNext = "Word \xC2\xBB";
+    sideTop = "Line Up";     sideBottom = "Line Dn";
+  }
+
+  const auto labels = mappedInput.mapLabels("\xC2\xAB Back", "Select", facePrev, faceNext);
+  const char* btnLabels[] = {labels.btn1, labels.btn2, labels.btn3, labels.btn4};
+  const char* sideLabels[] = {sideTop, sideBottom};
+
+  // ---- Determine which hints overlap the selected word ----
+  bool hideHint[4] = {false, false, false, false};
+  bool hideSide[2] = {false, false};
+
+  if (!words.empty() && currentRow < static_cast<int>(rows.size())) {
+    const int lineHeight = renderer.getLineHeight(fontId);
+
+    // Collect bounding boxes of the selected word (and its continuation) in current-orientation coords.
+    struct Box {
+      int x, y, w, h;
+    };
+    Box boxes[2];
+    int boxCount = 0;
+
+    int wordIdx = rows[currentRow].wordIndices[currentWordInRow];
+    const auto& sel = words[wordIdx];
+    boxes[0] = {sel.screenX - 1, sel.screenY - 1, sel.width + 2, lineHeight + 2};
+    boxCount = 1;
+
+    int otherIdx = (sel.continuationOf >= 0) ? sel.continuationOf : -1;
+    if (otherIdx < 0 && sel.continuationIndex >= 0 && sel.continuationIndex != wordIdx) {
+      otherIdx = sel.continuationIndex;
+    }
+    if (otherIdx >= 0) {
+      const auto& other = words[otherIdx];
+      boxes[1] = {other.screenX - 1, other.screenY - 1, other.width + 2, lineHeight + 2};
+      boxCount = 2;
+    }
+
+    // Convert each box from the current orientation to portrait coordinates,
+    // then check overlap against both bottom and side button hints.
+    for (int b = 0; b < boxCount; b++) {
+      int px, py, pw, ph;
+
+      if (origOrientation == GfxRenderer::Orientation::Portrait) {
+        px = boxes[b].x;
+        py = boxes[b].y;
+        pw = boxes[b].w;
+        ph = boxes[b].h;
+      } else if (origOrientation == GfxRenderer::Orientation::PortraitInverted) {
+        px = portW - boxes[b].x - boxes[b].w;
+        py = portH - boxes[b].y - boxes[b].h;
+        pw = boxes[b].w;
+        ph = boxes[b].h;
+      } else if (origOrientation == GfxRenderer::Orientation::LandscapeClockwise) {
+        px = boxes[b].y;
+        py = portH - boxes[b].x - boxes[b].w;
+        pw = boxes[b].h;
+        ph = boxes[b].w;
+      } else {
+        px = portW - boxes[b].y - boxes[b].h;
+        py = boxes[b].x;
+        pw = boxes[b].h;
+        ph = boxes[b].w;
+      }
+
+      // Bottom button overlap
+      int hintTop = portH - buttonHeight;
+      if (py + ph > hintTop) {
+        for (int i = 0; i < 4; i++) {
+          if (px + pw > buttonPositions[i] && px < buttonPositions[i] + buttonWidth) {
+            hideHint[i] = true;
+          }
+        }
+      }
+
+      // Side button overlap
+      if (px + pw > sideX) {
+        for (int s = 0; s < 2; s++) {
+          if (py + ph > sideButtonY[s] && py < sideButtonY[s] + sideButtonHeight) {
+            hideSide[s] = true;
+          }
+        }
+      }
+    }
+  }
+
+  // ---- Draw all hints in portrait mode ----
+  // Hidden buttons are skipped entirely so the page content underneath stays visible.
+  renderer.setOrientation(GfxRenderer::Orientation::Portrait);
+
+  // Bottom face buttons
+  for (int i = 0; i < 4; i++) {
+    if (hideHint[i]) continue;
+
+    const int x = buttonPositions[i];
+    renderer.fillRect(x, portH - buttonHeight, buttonWidth, buttonHeight, false);
+
+    if (btnLabels[i] != nullptr && btnLabels[i][0] != '\0') {
+      renderer.drawRoundedRect(x, portH - buttonHeight, buttonWidth, buttonHeight, 1, cornerRadius, true, true, false,
+                               false, true);
+      const int tw = renderer.getTextWidth(SMALL_FONT_ID, btnLabels[i]);
+      const int tx = x + (buttonWidth - 1 - tw) / 2;
+      renderer.drawText(SMALL_FONT_ID, tx, portH - buttonHeight + textYOffset, btnLabels[i]);
+    } else {
+      renderer.drawRoundedRect(x, portH - smallButtonHeight, buttonWidth, smallButtonHeight, 1, cornerRadius, true,
+                               true, false, false, true);
+    }
+  }
+
+  // Side buttons (custom-drawn with background, overlap hiding, truncation, and rotation)
+  const bool useCCW = (orientation == CrossPointSettings::ORIENTATION::LANDSCAPE_CCW);
+
+  for (int i = 0; i < 2; i++) {
+    if (hideSide[i]) continue;
+    if (sideLabels[i] == nullptr || sideLabels[i][0] == '\0') continue;
+
+    // Solid background
+    renderer.fillRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, false);
+
+    // Outline (rounded on inner side, square on screen edge — matches theme)
+    renderer.drawRoundedRect(sideX, sideButtonY[i], sideButtonWidth, sideButtonHeight, 1, cornerRadius, true, false,
+                             true, false, true);
+
+    // Truncate text if it would overflow the button height
+    const std::string truncated = renderer.truncatedText(SMALL_FONT_ID, sideLabels[i], sideButtonHeight);
+    const int tw = renderer.getTextWidth(SMALL_FONT_ID, truncated.c_str());
+
+    if (useCCW) {
+      // Text reads top-to-bottom (90° CCW rotation): y starts near top of button
+      renderer.drawTextRotated90CCW(SMALL_FONT_ID, sideX,
+                                    sideButtonY[i] + (sideButtonHeight - tw) / 2, truncated.c_str());
+    } else {
+      // Text reads bottom-to-top (90° CW rotation): y starts near bottom of button
+      renderer.drawTextRotated90CW(SMALL_FONT_ID, sideX,
+                                   sideButtonY[i] + (sideButtonHeight + tw) / 2, truncated.c_str());
+    }
+  }
+
+  renderer.setOrientation(origOrientation);
+}

src/activities/reader/DictionaryWordSelectActivity.h

@@ -0,0 +1,80 @@
+#pragma once
+#include <Epub/Page.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "../Activity.h"
+
+class DictionaryWordSelectActivity final : public Activity {
+ public:
+  explicit DictionaryWordSelectActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                        std::unique_ptr<Page> page, int fontId, int marginLeft, int marginTop,
+                                        const std::string& cachePath, uint8_t orientation,
+                                        const std::function<void()>& onBack,
+                                        const std::function<void(const std::string&, const std::string&)>& onLookup)
+      : Activity("DictionaryWordSelect", renderer, mappedInput),
+        page(std::move(page)),
+        fontId(fontId),
+        marginLeft(marginLeft),
+        marginTop(marginTop),
+        cachePath(cachePath),
+        orientation(orientation),
+        onBack(onBack),
+        onLookup(onLookup) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+
+ private:
+  struct WordInfo {
+    std::string text;
+    std::string lookupText;
+    int16_t screenX;
+    int16_t screenY;
+    int16_t width;
+    int16_t row;
+    int continuationIndex;
+    int continuationOf;
+    WordInfo(const std::string& t, int16_t x, int16_t y, int16_t w, int16_t r)
+        : text(t), lookupText(t), screenX(x), screenY(y), width(w), row(r), continuationIndex(-1), continuationOf(-1) {}
+  };
+
+  struct Row {
+    int16_t yPos;
+    std::vector<int> wordIndices;
+  };
+
+  std::unique_ptr<Page> page;
+  int fontId;
+  int marginLeft;
+  int marginTop;
+  std::string cachePath;
+  uint8_t orientation;
+  const std::function<void()> onBack;
+  const std::function<void(const std::string&, const std::string&)> onLookup;
+
+  std::vector<WordInfo> words;
+  std::vector<Row> rows;
+  int currentRow = 0;
+  int currentWordInRow = 0;
+  bool updateRequired = false;
+
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+
+  bool isLandscape() const;
+  bool isInverted() const;
+  void extractWords();
+  void mergeHyphenatedWords();
+  void renderScreen();
+  void drawHints();
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+};

src/activities/reader/EpubReaderActivity.cpp

@@ -15,6 +15,8 @@
 #include "RecentBooksStore.h"
 #include "components/UITheme.h"
 #include "fontIds.h"
+#include "util/Dictionary.h"
+#include "util/LookupHistory.h"
 
 namespace {
 // pagesPerRefresh now comes from SETTINGS.getRefreshFrequency()
@@ -232,10 +234,11 @@ void EpubReaderActivity::loop() {
       bookProgress = epub->calculateProgress(currentSpineIndex, chapterProgress) * 100.0f;
     }
     const int bookProgressPercent = clampPercent(static_cast<int>(bookProgress + 0.5f));
+    const bool hasDictionary = Dictionary::exists();
     exitActivity();
     enterNewActivity(new EpubReaderMenuActivity(
         this->renderer, this->mappedInput, epub->getTitle(), currentPage, totalPages, bookProgressPercent,
-        SETTINGS.orientation, [this](const uint8_t orientation) { onReaderMenuBack(orientation); },
+        SETTINGS.orientation, hasDictionary, [this](const uint8_t orientation) { onReaderMenuBack(orientation); },
         [this](EpubReaderMenuActivity::MenuAction action) { onReaderMenuConfirm(action); }));
     xSemaphoreGive(renderingMutex);
   }
@@ -396,6 +399,40 @@ void EpubReaderActivity::jumpToPercent(int percent) {
 
 void EpubReaderActivity::onReaderMenuConfirm(EpubReaderMenuActivity::MenuAction action) {
   switch (action) {
+    case EpubReaderMenuActivity::MenuAction::ADD_BOOKMARK: {
+      // Stub — bookmark feature coming soon
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      GUI.drawPopup(renderer, "Coming soon");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      xSemaphoreGive(renderingMutex);
+      vTaskDelay(1500 / portTICK_PERIOD_MS);
+      break;
+    }
+    case EpubReaderMenuActivity::MenuAction::GO_TO_BOOKMARK: {
+      // Stub — bookmark feature coming soon
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      GUI.drawPopup(renderer, "Coming soon");
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+      xSemaphoreGive(renderingMutex);
+      vTaskDelay(1500 / portTICK_PERIOD_MS);
+      break;
+    }
+    case EpubReaderMenuActivity::MenuAction::DELETE_DICT_CACHE: {
+      if (Dictionary::cacheExists()) {
+        Dictionary::deleteCache();
+        xSemaphoreTake(renderingMutex, portMAX_DELAY);
+        GUI.drawPopup(renderer, "Dictionary cache deleted");
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+        xSemaphoreGive(renderingMutex);
+      } else {
+        xSemaphoreTake(renderingMutex, portMAX_DELAY);
+        GUI.drawPopup(renderer, "No cache to delete");
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+        xSemaphoreGive(renderingMutex);
+      }
+      vTaskDelay(1500 / portTICK_PERIOD_MS);
+      break;
+    }
     case EpubReaderMenuActivity::MenuAction::SELECT_CHAPTER: {
       // Calculate values BEFORE we start destroying things
       const int currentP = section ? section->currentPage : 0;
@@ -463,6 +500,92 @@ void EpubReaderActivity::onReaderMenuConfirm(EpubReaderMenuActivity::MenuAction
       xSemaphoreGive(renderingMutex);
       break;
     }
+    case EpubReaderMenuActivity::MenuAction::LOOKUP: {
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+
+      // Compute margins (same logic as renderScreen)
+      int orientedMarginTop, orientedMarginRight, orientedMarginBottom, orientedMarginLeft;
+      renderer.getOrientedViewableTRBL(&orientedMarginTop, &orientedMarginRight, &orientedMarginBottom,
+                                       &orientedMarginLeft);
+      orientedMarginTop += SETTINGS.screenMargin;
+      orientedMarginLeft += SETTINGS.screenMargin;
+      orientedMarginRight += SETTINGS.screenMargin;
+      orientedMarginBottom += SETTINGS.screenMargin;
+
+      if (SETTINGS.statusBar != CrossPointSettings::STATUS_BAR_MODE::NONE) {
+        auto metrics = UITheme::getInstance().getMetrics();
+        const bool showProgressBar =
+            SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::BOOK_PROGRESS_BAR ||
+            SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::ONLY_BOOK_PROGRESS_BAR ||
+            SETTINGS.statusBar == CrossPointSettings::STATUS_BAR_MODE::CHAPTER_PROGRESS_BAR;
+        orientedMarginBottom += statusBarMargin - SETTINGS.screenMargin +
+                                (showProgressBar ? (metrics.bookProgressBarHeight + progressBarMarginTop) : 0);
+      }
+
+      // Load the current page
+      auto pageForLookup = section ? section->loadPageFromSectionFile() : nullptr;
+      const int readerFontId = SETTINGS.getReaderFontId();
+      const std::string bookCachePath = epub->getCachePath();
+      const uint8_t currentOrientation = SETTINGS.orientation;
+
+      exitActivity();
+
+      if (pageForLookup) {
+        enterNewActivity(new DictionaryWordSelectActivity(
+            renderer, mappedInput, std::move(pageForLookup), readerFontId, orientedMarginLeft, orientedMarginTop,
+            bookCachePath, currentOrientation,
+            [this]() {
+              // On back from word select
+              pendingSubactivityExit = true;
+            },
+            [this, bookCachePath, readerFontId, currentOrientation](const std::string& headword,
+                                                                    const std::string& definition) {
+              // On successful lookup - show definition
+              exitActivity();
+              enterNewActivity(new DictionaryDefinitionActivity(renderer, mappedInput, headword, definition,
+                                                                readerFontId, currentOrientation,
+                                                                [this]() { pendingSubactivityExit = true; }));
+            }));
+      }
+
+      xSemaphoreGive(renderingMutex);
+      break;
+    }
+    case EpubReaderMenuActivity::MenuAction::LOOKED_UP_WORDS: {
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      const std::string bookCachePath = epub->getCachePath();
+      const int readerFontId = SETTINGS.getReaderFontId();
+      const uint8_t currentOrientation = SETTINGS.orientation;
+
+      exitActivity();
+      enterNewActivity(new LookedUpWordsActivity(
+          renderer, mappedInput, bookCachePath,
+          [this]() {
+            // On back from looked up words
+            pendingSubactivityExit = true;
+          },
+          [this, bookCachePath, readerFontId, currentOrientation](const std::string& headword) {
+            // Look up the word and show definition with progress bar
+            Rect popupLayout = GUI.drawPopup(renderer, "Looking up...");
+
+            std::string definition = Dictionary::lookup(
+                headword, [this, &popupLayout](int percent) { GUI.fillPopupProgress(renderer, popupLayout, percent); });
+
+            if (definition.empty()) {
+              GUI.drawPopup(renderer, "Not found");
+              renderer.displayBuffer(HalDisplay::FAST_REFRESH);
+              vTaskDelay(1500 / portTICK_PERIOD_MS);
+              return;
+            }
+
+            exitActivity();
+            enterNewActivity(new DictionaryDefinitionActivity(renderer, mappedInput, headword, definition, readerFontId,
+                                                              currentOrientation,
+                                                              [this]() { pendingSubactivityExit = true; }));
+          }));
+      xSemaphoreGive(renderingMutex);
+      break;
+    }
     case EpubReaderMenuActivity::MenuAction::GO_HOME: {
       // Defer go home to avoid race condition with display task
       pendingGoHome = true;

src/activities/reader/EpubReaderActivity.h

@@ -5,7 +5,10 @@
 #include <freertos/semphr.h>
 #include <freertos/task.h>
 
+#include "DictionaryDefinitionActivity.h"
+#include "DictionaryWordSelectActivity.h"
 #include "EpubReaderMenuActivity.h"
+#include "LookedUpWordsActivity.h"
 #include "activities/ActivityWithSubactivity.h"
 
 class EpubReaderActivity final : public ActivityWithSubactivity {

src/activities/reader/EpubReaderMenuActivity.h

@@ -14,13 +14,27 @@
 class EpubReaderMenuActivity final : public ActivityWithSubactivity {
  public:
   // Menu actions available from the reader menu.
-  enum class MenuAction { SELECT_CHAPTER, GO_TO_PERCENT, ROTATE_SCREEN, GO_HOME, SYNC, DELETE_CACHE };
+  enum class MenuAction {
+    ADD_BOOKMARK,
+    LOOKUP,
+    LOOKED_UP_WORDS,
+    ROTATE_SCREEN,
+    SELECT_CHAPTER,
+    GO_TO_BOOKMARK,
+    GO_TO_PERCENT,
+    GO_HOME,
+    SYNC,
+    DELETE_CACHE,
+    DELETE_DICT_CACHE
+  };
 
   explicit EpubReaderMenuActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, const std::string& title,
                                   const int currentPage, const int totalPages, const int bookProgressPercent,
-                                  const uint8_t currentOrientation, const std::function<void(uint8_t)>& onBack,
+                                  const uint8_t currentOrientation, const bool hasDictionary,
+                                  const std::function<void(uint8_t)>& onBack,
                                   const std::function<void(MenuAction)>& onAction)
       : ActivityWithSubactivity("EpubReaderMenu", renderer, mappedInput),
+        menuItems(buildMenuItems(hasDictionary)),
         title(title),
         pendingOrientation(currentOrientation),
         currentPage(currentPage),
@@ -39,11 +53,7 @@ class EpubReaderMenuActivity final : public ActivityWithSubactivity {
     std::string label;
   };
 
-  // Fixed menu layout (order matters for up/down navigation).
+  std::vector<MenuItem> menuItems;
-  const std::vector<MenuItem> menuItems = {
-      {MenuAction::SELECT_CHAPTER, "Go to Chapter"}, {MenuAction::ROTATE_SCREEN, "Reading Orientation"},
-      {MenuAction::GO_TO_PERCENT, "Go to %"},        {MenuAction::GO_HOME, "Go Home"},
-      {MenuAction::SYNC, "Sync Progress"},           {MenuAction::DELETE_CACHE, "Delete Book Cache"}};
 
   int selectedIndex = 0;
   bool updateRequired = false;
@@ -60,6 +70,26 @@ class EpubReaderMenuActivity final : public ActivityWithSubactivity {
   const std::function<void(uint8_t)> onBack;
   const std::function<void(MenuAction)> onAction;
 
+  static std::vector<MenuItem> buildMenuItems(bool hasDictionary) {
+    std::vector<MenuItem> items;
+    items.push_back({MenuAction::ADD_BOOKMARK, "Add Bookmark"});
+    if (hasDictionary) {
+      items.push_back({MenuAction::LOOKUP, "Lookup Word"});
+      items.push_back({MenuAction::LOOKED_UP_WORDS, "Lookup Word History"});
+    }
+    items.push_back({MenuAction::ROTATE_SCREEN, "Reading Orientation"});
+    items.push_back({MenuAction::SELECT_CHAPTER, "Table of Contents"});
+    items.push_back({MenuAction::GO_TO_BOOKMARK, "Go to Bookmark"});
+    items.push_back({MenuAction::GO_TO_PERCENT, "Go to %"});
+    items.push_back({MenuAction::GO_HOME, "Close Book"});
+    items.push_back({MenuAction::SYNC, "Sync Progress"});
+    items.push_back({MenuAction::DELETE_CACHE, "Delete Book Cache"});
+    if (hasDictionary) {
+      items.push_back({MenuAction::DELETE_DICT_CACHE, "Delete Dictionary Cache"});
+    }
+    return items;
+  }
+
   static void taskTrampoline(void* param);
   [[noreturn]] void displayTaskLoop();
   void renderScreen();

src/activities/reader/LookedUpWordsActivity.cpp

@@ -0,0 +1,196 @@
+#include "LookedUpWordsActivity.h"
+
+#include <GfxRenderer.h>
+
+#include <algorithm>
+
+#include "MappedInputManager.h"
+#include "components/UITheme.h"
+#include "fontIds.h"
+#include "util/LookupHistory.h"
+
+void LookedUpWordsActivity::taskTrampoline(void* param) {
+  auto* self = static_cast<LookedUpWordsActivity*>(param);
+  self->displayTaskLoop();
+}
+
+void LookedUpWordsActivity::displayTaskLoop() {
+  while (true) {
+    if (updateRequired && !subActivity) {
+      updateRequired = false;
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      renderScreen();
+      xSemaphoreGive(renderingMutex);
+    }
+    vTaskDelay(10 / portTICK_PERIOD_MS);
+  }
+}
+
+void LookedUpWordsActivity::onEnter() {
+  ActivityWithSubactivity::onEnter();
+  renderingMutex = xSemaphoreCreateMutex();
+  words = LookupHistory::load(cachePath);
+  updateRequired = true;
+  xTaskCreate(&LookedUpWordsActivity::taskTrampoline, "LookedUpTask", 4096, this, 1, &displayTaskHandle);
+}
+
+void LookedUpWordsActivity::onExit() {
+  ActivityWithSubactivity::onExit();
+  xSemaphoreTake(renderingMutex, portMAX_DELAY);
+  if (displayTaskHandle) {
+    vTaskDelete(displayTaskHandle);
+    displayTaskHandle = nullptr;
+  }
+  vSemaphoreDelete(renderingMutex);
+  renderingMutex = nullptr;
+}
+
+void LookedUpWordsActivity::loop() {
+  if (subActivity) {
+    subActivity->loop();
+    return;
+  }
+
+  if (words.empty()) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Back) ||
+        mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+      onBack();
+    }
+    return;
+  }
+
+  // Delete confirmation mode: wait for confirm (delete) or back (cancel)
+  if (deleteConfirmMode) {
+    if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+      if (ignoreNextConfirmRelease) {
+        // Ignore the release from the initial long press
+        ignoreNextConfirmRelease = false;
+      } else {
+        // Confirm delete
+        LookupHistory::removeWord(cachePath, words[pendingDeleteIndex]);
+        words.erase(words.begin() + pendingDeleteIndex);
+        if (selectedIndex >= static_cast<int>(words.size())) {
+          selectedIndex = std::max(0, static_cast<int>(words.size()) - 1);
+        }
+        deleteConfirmMode = false;
+        updateRequired = true;
+      }
+    }
+    if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+      deleteConfirmMode = false;
+      ignoreNextConfirmRelease = false;
+      updateRequired = true;
+    }
+    return;
+  }
+
+  // Detect long press on Confirm to trigger delete
+  constexpr unsigned long DELETE_HOLD_MS = 700;
+  if (mappedInput.isPressed(MappedInputManager::Button::Confirm) && mappedInput.getHeldTime() >= DELETE_HOLD_MS) {
+    deleteConfirmMode = true;
+    ignoreNextConfirmRelease = true;
+    pendingDeleteIndex = selectedIndex;
+    updateRequired = true;
+    return;
+  }
+
+  buttonNavigator.onNext([this] {
+    selectedIndex = ButtonNavigator::nextIndex(selectedIndex, static_cast<int>(words.size()));
+    updateRequired = true;
+  });
+
+  buttonNavigator.onPrevious([this] {
+    selectedIndex = ButtonNavigator::previousIndex(selectedIndex, static_cast<int>(words.size()));
+    updateRequired = true;
+  });
+
+  if (mappedInput.wasReleased(MappedInputManager::Button::Confirm)) {
+    onSelectWord(words[selectedIndex]);
+    return;
+  }
+
+  if (mappedInput.wasReleased(MappedInputManager::Button::Back)) {
+    onBack();
+    return;
+  }
+}
+
+void LookedUpWordsActivity::renderScreen() {
+  renderer.clearScreen();
+
+  constexpr int sidePadding = 20;
+  constexpr int titleY = 15;
+  constexpr int startY = 60;
+  constexpr int lineHeight = 30;
+
+  // Title
+  const int titleX =
+      (renderer.getScreenWidth() - renderer.getTextWidth(UI_12_FONT_ID, "Lookup History", EpdFontFamily::BOLD)) / 2;
+  renderer.drawText(UI_12_FONT_ID, titleX, titleY, "Lookup History", true, EpdFontFamily::BOLD);
+
+  if (words.empty()) {
+    renderer.drawCenteredText(UI_10_FONT_ID, 300, "No words looked up yet");
+  } else {
+    const int screenHeight = renderer.getScreenHeight();
+    const int pageItems = std::max(1, (screenHeight - startY - 40) / lineHeight);
+    const int pageStart = selectedIndex / pageItems * pageItems;
+
+    for (int i = 0; i < pageItems; i++) {
+      int idx = pageStart + i;
+      if (idx >= static_cast<int>(words.size())) break;
+
+      const int displayY = startY + i * lineHeight;
+      const bool isSelected = (idx == selectedIndex);
+
+      if (isSelected) {
+        renderer.fillRect(0, displayY - 2, renderer.getScreenWidth() - 1, lineHeight);
+      }
+
+      renderer.drawText(UI_10_FONT_ID, sidePadding, displayY, words[idx].c_str(), !isSelected);
+    }
+  }
+
+  if (deleteConfirmMode && pendingDeleteIndex < static_cast<int>(words.size())) {
+    // Draw delete confirmation overlay
+    const std::string& word = words[pendingDeleteIndex];
+    std::string displayWord = word;
+    if (displayWord.size() > 20) {
+      displayWord.erase(17);
+      displayWord += "...";
+    }
+    std::string msg = "Delete '" + displayWord + "'?";
+
+    constexpr int margin = 15;
+    constexpr int popupY = 200;
+    const int textWidth = renderer.getTextWidth(UI_12_FONT_ID, msg.c_str(), EpdFontFamily::BOLD);
+    const int textHeight = renderer.getLineHeight(UI_12_FONT_ID);
+    const int w = textWidth + margin * 2;
+    const int h = textHeight + margin * 2;
+    const int x = (renderer.getScreenWidth() - w) / 2;
+
+    renderer.fillRect(x - 2, popupY - 2, w + 4, h + 4, true);
+    renderer.fillRect(x, popupY, w, h, false);
+
+    const int textX = x + (w - textWidth) / 2;
+    const int textY = popupY + margin - 2;
+    renderer.drawText(UI_12_FONT_ID, textX, textY, msg.c_str(), true, EpdFontFamily::BOLD);
+
+    // Button hints for delete mode
+    const auto labels = mappedInput.mapLabels("Cancel", "Delete", "", "");
+    GUI.drawButtonHints(renderer, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+  } else {
+    // "Hold select to delete" hint above button hints
+    if (!words.empty()) {
+      const char* deleteHint = "Hold select to delete";
+      const int hintWidth = renderer.getTextWidth(SMALL_FONT_ID, deleteHint);
+      renderer.drawText(SMALL_FONT_ID, (renderer.getScreenWidth() - hintWidth) / 2, renderer.getScreenHeight() - 70,
+                        deleteHint);
+    }
+
+    // Normal button hints
+    const auto labels = mappedInput.mapLabels("\xC2\xAB Back", "Select", "^", "v");
+    GUI.drawButtonHints(renderer, labels.btn1, labels.btn2, labels.btn3, labels.btn4);
+  }
+
+  renderer.displayBuffer();
+}

src/activities/reader/LookedUpWordsActivity.h

@@ -0,0 +1,48 @@
+#pragma once
+#include <freertos/FreeRTOS.h>
+#include <freertos/semphr.h>
+#include <freertos/task.h>
+
+#include <functional>
+#include <string>
+#include <vector>
+
+#include "../ActivityWithSubactivity.h"
+#include "util/ButtonNavigator.h"
+
+class LookedUpWordsActivity final : public ActivityWithSubactivity {
+ public:
+  explicit LookedUpWordsActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, const std::string& cachePath,
+                                 const std::function<void()>& onBack,
+                                 const std::function<void(const std::string&)>& onSelectWord)
+      : ActivityWithSubactivity("LookedUpWords", renderer, mappedInput),
+        cachePath(cachePath),
+        onBack(onBack),
+        onSelectWord(onSelectWord) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+
+ private:
+  std::string cachePath;
+  const std::function<void()> onBack;
+  const std::function<void(const std::string&)> onSelectWord;
+
+  std::vector<std::string> words;
+  int selectedIndex = 0;
+  bool updateRequired = false;
+  ButtonNavigator buttonNavigator;
+
+  // Delete confirmation state
+  bool deleteConfirmMode = false;
+  bool ignoreNextConfirmRelease = false;
+  int pendingDeleteIndex = 0;
+
+  TaskHandle_t displayTaskHandle = nullptr;
+  SemaphoreHandle_t renderingMutex = nullptr;
+
+  void renderScreen();
+  static void taskTrampoline(void* param);
+  [[noreturn]] void displayTaskLoop();
+};

src/util/Dictionary.cpp

@@ -0,0 +1,328 @@
+#include "Dictionary.h"
+
+#include <HalStorage.h>
+
+#include <algorithm>
+#include <cctype>
+#include <cstring>
+
+namespace {
+constexpr const char* IDX_PATH = "/.dictionary/dictionary.idx";
+constexpr const char* DICT_PATH = "/.dictionary/dictionary.dict";
+constexpr const char* CACHE_PATH = "/.dictionary/dictionary.cache";
+constexpr uint32_t CACHE_MAGIC = 0x44494358;  // "DICX"
+
+// g_ascii_strcasecmp equivalent: compare lowercasing only ASCII A-Z.
+int asciiCaseCmp(const char* s1, const char* s2) {
+  const auto* p1 = reinterpret_cast<const unsigned char*>(s1);
+  const auto* p2 = reinterpret_cast<const unsigned char*>(s2);
+  while (*p1 && *p2) {
+    unsigned char c1 = *p1, c2 = *p2;
+    if (c1 >= 'A' && c1 <= 'Z') c1 += 32;
+    if (c2 >= 'A' && c2 <= 'Z') c2 += 32;
+    if (c1 != c2) return static_cast<int>(c1) - static_cast<int>(c2);
+    ++p1;
+    ++p2;
+  }
+  return static_cast<int>(*p1) - static_cast<int>(*p2);
+}
+
+// StarDict index comparison: case-insensitive first, then case-sensitive tiebreaker.
+// This matches the stardict_strcmp used by StarDict to sort .idx entries.
+int stardictCmp(const char* s1, const char* s2) {
+  int ci = asciiCaseCmp(s1, s2);
+  if (ci != 0) return ci;
+  return std::strcmp(s1, s2);
+}
+}  // namespace
+
+std::vector<uint32_t> Dictionary::sparseOffsets;
+uint32_t Dictionary::totalWords = 0;
+bool Dictionary::indexLoaded = false;
+
+bool Dictionary::exists() { return Storage.exists(IDX_PATH); }
+
+bool Dictionary::cacheExists() { return Storage.exists(CACHE_PATH); }
+
+void Dictionary::deleteCache() {
+  Storage.remove(CACHE_PATH);
+  // Reset in-memory state so next lookup rebuilds from the .idx file.
+  sparseOffsets.clear();
+  totalWords = 0;
+  indexLoaded = false;
+}
+
+std::string Dictionary::cleanWord(const std::string& word) {
+  if (word.empty()) return "";
+
+  // Find first alphanumeric character
+  size_t start = 0;
+  while (start < word.size() && !std::isalnum(static_cast<unsigned char>(word[start]))) {
+    start++;
+  }
+
+  // Find last alphanumeric character
+  size_t end = word.size();
+  while (end > start && !std::isalnum(static_cast<unsigned char>(word[end - 1]))) {
+    end--;
+  }
+
+  if (start >= end) return "";
+
+  std::string result = word.substr(start, end - start);
+  // Lowercase
+  std::transform(result.begin(), result.end(), result.begin(), [](unsigned char c) { return std::tolower(c); });
+  return result;
+}
+
+// ---------------------------------------------------------------------------
+// Cache: persists the sparse offset table to SD card so subsequent boots skip
+// the full .idx scan.  The cache is invalidated when the .idx file size changes.
+//
+// Format: [magic 4B][idxFileSize 4B][totalWords 4B][count 4B][offsets N×4B]
+// All values are stored in native byte order (little-endian on ESP32).
+// ---------------------------------------------------------------------------
+bool Dictionary::loadCachedIndex() {
+  FsFile idx;
+  if (!Storage.openFileForRead("DICT", IDX_PATH, idx)) return false;
+  const uint32_t idxFileSize = static_cast<uint32_t>(idx.fileSize());
+  idx.close();
+
+  FsFile cache;
+  if (!Storage.openFileForRead("DICT", CACHE_PATH, cache)) return false;
+
+  // Read and validate header
+  uint32_t header[4];  // magic, idxFileSize, totalWords, count
+  if (cache.read(reinterpret_cast<uint8_t*>(header), 16) != 16) {
+    cache.close();
+    return false;
+  }
+
+  if (header[0] != CACHE_MAGIC || header[1] != idxFileSize) {
+    cache.close();
+    return false;
+  }
+
+  totalWords = header[2];
+  const uint32_t count = header[3];
+
+  sparseOffsets.resize(count);
+  const int bytesToRead = static_cast<int>(count * sizeof(uint32_t));
+  if (cache.read(reinterpret_cast<uint8_t*>(sparseOffsets.data()), bytesToRead) != bytesToRead) {
+    cache.close();
+    sparseOffsets.clear();
+    totalWords = 0;
+    return false;
+  }
+
+  cache.close();
+  indexLoaded = true;
+  return true;
+}
+
+void Dictionary::saveCachedIndex(uint32_t idxFileSize) {
+  FsFile cache;
+  if (!Storage.openFileForWrite("DICT", CACHE_PATH, cache)) return;
+
+  const uint32_t count = static_cast<uint32_t>(sparseOffsets.size());
+  uint32_t header[4] = {CACHE_MAGIC, idxFileSize, totalWords, count};
+
+  cache.write(reinterpret_cast<const uint8_t*>(header), 16);
+  cache.write(reinterpret_cast<const uint8_t*>(sparseOffsets.data()), count * sizeof(uint32_t));
+  cache.close();
+}
+
+// Scan the .idx file to build a sparse offset table for fast lookups.
+// Records the file offset of every SPARSE_INTERVAL-th entry.
+bool Dictionary::loadIndex(const std::function<void(int percent)>& onProgress,
+                           const std::function<bool()>& shouldCancel) {
+  // Try loading from cache first (nearly instant)
+  if (loadCachedIndex()) return true;
+
+  FsFile idx;
+  if (!Storage.openFileForRead("DICT", IDX_PATH, idx)) return false;
+
+  const uint32_t fileSize = static_cast<uint32_t>(idx.fileSize());
+
+  sparseOffsets.clear();
+  totalWords = 0;
+
+  uint32_t pos = 0;
+  int lastReportedPercent = -1;
+
+  while (pos < fileSize) {
+    if (shouldCancel && (totalWords % 100 == 0) && shouldCancel()) {
+      idx.close();
+      sparseOffsets.clear();
+      totalWords = 0;
+      return false;
+    }
+
+    if (totalWords % SPARSE_INTERVAL == 0) {
+      sparseOffsets.push_back(pos);
+    }
+
+    // Skip word (read until null terminator)
+    int ch;
+    do {
+      ch = idx.read();
+      if (ch < 0) {
+        pos = fileSize;
+        break;
+      }
+      pos++;
+    } while (ch != 0);
+
+    if (pos >= fileSize) break;
+
+    // Skip 8 bytes (4-byte offset + 4-byte size)
+    uint8_t skip[8];
+    if (idx.read(skip, 8) != 8) break;
+    pos += 8;
+
+    totalWords++;
+
+    if (onProgress && fileSize > 0) {
+      int percent = static_cast<int>(static_cast<uint64_t>(pos) * 90 / fileSize);
+      if (percent > lastReportedPercent + 4) {
+        lastReportedPercent = percent;
+        onProgress(percent);
+      }
+    }
+  }
+
+  idx.close();
+  indexLoaded = true;
+
+  // Persist to cache so next boot is instant
+  if (totalWords > 0) saveCachedIndex(fileSize);
+
+  return totalWords > 0;
+}
+
+// Read a null-terminated word string from the current file position.
+std::string Dictionary::readWord(FsFile& file) {
+  std::string word;
+  while (true) {
+    int ch = file.read();
+    if (ch <= 0) break;  // null terminator (0) or error (-1)
+    word += static_cast<char>(ch);
+  }
+  return word;
+}
+
+// Read a definition from the .dict file at the given offset and size.
+std::string Dictionary::readDefinition(uint32_t offset, uint32_t size) {
+  FsFile dict;
+  if (!Storage.openFileForRead("DICT", DICT_PATH, dict)) return "";
+
+  dict.seekSet(offset);
+
+  std::string def(size, '\0');
+  int bytesRead = dict.read(reinterpret_cast<uint8_t*>(&def[0]), size);
+  dict.close();
+
+  if (bytesRead < 0) return "";
+  if (static_cast<uint32_t>(bytesRead) < size) def.resize(bytesRead);
+  return def;
+}
+
+// Binary search the sparse offset table, then linear scan within the matching segment.
+// Uses StarDict's sort order: case-insensitive first, then case-sensitive tiebreaker.
+// The exact match is case-insensitive so e.g. "simple" matches "Simple".
+std::string Dictionary::searchIndex(const std::string& word, const std::function<bool()>& shouldCancel) {
+  if (sparseOffsets.empty()) return "";
+
+  FsFile idx;
+  if (!Storage.openFileForRead("DICT", IDX_PATH, idx)) return "";
+
+  // Binary search the sparse offset table to find the right segment.
+  int lo = 0, hi = static_cast<int>(sparseOffsets.size()) - 1;
+
+  while (lo < hi) {
+    if (shouldCancel && shouldCancel()) {
+      idx.close();
+      return "";
+    }
+
+    int mid = lo + (hi - lo + 1) / 2;
+    idx.seekSet(sparseOffsets[mid]);
+    std::string key = readWord(idx);
+
+    if (stardictCmp(key.c_str(), word.c_str()) <= 0) {
+      lo = mid;
+    } else {
+      hi = mid - 1;
+    }
+  }
+
+  // Linear scan within the segment starting at sparseOffsets[lo].
+  idx.seekSet(sparseOffsets[lo]);
+
+  int maxEntries = SPARSE_INTERVAL;
+  if (lo == static_cast<int>(sparseOffsets.size()) - 1) {
+    maxEntries = static_cast<int>(totalWords - static_cast<uint32_t>(lo) * SPARSE_INTERVAL);
+  }
+
+  // Scan entries, preferring an exact case-sensitive match over a case-insensitive one.
+  // In stardict order, all case variants of a word are adjacent (e.g. "Professor" then "professor"),
+  // and they may have different definitions.  We want the lowercase entry when the user searched
+  // for a lowercase word, falling back to any case variant.
+  uint32_t bestOffset = 0, bestSize = 0;
+  bool found = false;
+
+  for (int i = 0; i < maxEntries; i++) {
+    if (shouldCancel && shouldCancel()) {
+      idx.close();
+      return "";
+    }
+
+    std::string key = readWord(idx);
+    if (key.empty()) break;
+
+    // Read offset and size (4 bytes each, big-endian)
+    uint8_t buf[8];
+    if (idx.read(buf, 8) != 8) break;
+
+    uint32_t dictOffset = (static_cast<uint32_t>(buf[0]) << 24) | (static_cast<uint32_t>(buf[1]) << 16) |
+                          (static_cast<uint32_t>(buf[2]) << 8) | static_cast<uint32_t>(buf[3]);
+    uint32_t dictSize = (static_cast<uint32_t>(buf[4]) << 24) | (static_cast<uint32_t>(buf[5]) << 16) |
+                        (static_cast<uint32_t>(buf[6]) << 8) | static_cast<uint32_t>(buf[7]);
+
+    if (asciiCaseCmp(key.c_str(), word.c_str()) == 0) {
+      // Case-insensitive match — remember the first one as fallback
+      if (!found) {
+        bestOffset = dictOffset;
+        bestSize = dictSize;
+        found = true;
+      }
+      // Exact case-sensitive match — use immediately
+      if (key == word) {
+        idx.close();
+        return readDefinition(dictOffset, dictSize);
+      }
+    } else if (found) {
+      // We've moved past all case variants of this word — stop
+      break;
+    } else if (stardictCmp(key.c_str(), word.c_str()) > 0) {
+      // Past the target in StarDict sort order — stop scanning
+      break;
+    }
+  }
+
+  idx.close();
+  return found ? readDefinition(bestOffset, bestSize) : "";
+}
+
+std::string Dictionary::lookup(const std::string& word, const std::function<void(int percent)>& onProgress,
+                               const std::function<bool()>& shouldCancel) {
+  if (!indexLoaded) {
+    if (!loadIndex(onProgress, shouldCancel)) return "";
+  }
+
+  // searchIndex uses StarDict sort order + case-insensitive match,
+  // so a single pass handles all casing variants.
+  std::string result = searchIndex(word, shouldCancel);
+  if (onProgress) onProgress(100);
+  return result;
+}

src/util/Dictionary.h

@@ -0,0 +1,31 @@
+#pragma once
+#include <cstdint>
+#include <functional>
+#include <string>
+#include <vector>
+
+class FsFile;
+
+class Dictionary {
+ public:
+  static bool exists();
+  static bool cacheExists();
+  static void deleteCache();
+  static std::string lookup(const std::string& word, const std::function<void(int percent)>& onProgress = nullptr,
+                            const std::function<bool()>& shouldCancel = nullptr);
+  static std::string cleanWord(const std::string& word);
+
+ private:
+  static constexpr int SPARSE_INTERVAL = 512;
+
+  static std::vector<uint32_t> sparseOffsets;
+  static uint32_t totalWords;
+  static bool indexLoaded;
+
+  static bool loadIndex(const std::function<void(int percent)>& onProgress, const std::function<bool()>& shouldCancel);
+  static bool loadCachedIndex();
+  static void saveCachedIndex(uint32_t idxFileSize);
+  static std::string searchIndex(const std::string& word, const std::function<bool()>& shouldCancel);
+  static std::string readWord(FsFile& file);
+  static std::string readDefinition(uint32_t offset, uint32_t size);
+};

src/util/LookupHistory.cpp

@@ -0,0 +1,88 @@
+#include "LookupHistory.h"
+
+#include <HalStorage.h>
+
+#include <algorithm>
+
+std::string LookupHistory::filePath(const std::string& cachePath) { return cachePath + "/lookups.txt"; }
+
+bool LookupHistory::hasHistory(const std::string& cachePath) {
+  FsFile f;
+  if (!Storage.openFileForRead("LKH", filePath(cachePath), f)) {
+    return false;
+  }
+  bool nonEmpty = f.available() > 0;
+  f.close();
+  return nonEmpty;
+}
+
+std::vector<std::string> LookupHistory::load(const std::string& cachePath) {
+  std::vector<std::string> words;
+  FsFile f;
+  if (!Storage.openFileForRead("LKH", filePath(cachePath), f)) {
+    return words;
+  }
+
+  std::string line;
+  while (f.available() && static_cast<int>(words.size()) < MAX_ENTRIES) {
+    char c;
+    if (f.read(reinterpret_cast<uint8_t*>(&c), 1) != 1) break;
+    if (c == '\n') {
+      if (!line.empty()) {
+        words.push_back(line);
+        line.clear();
+      }
+    } else {
+      line += c;
+    }
+  }
+  if (!line.empty() && static_cast<int>(words.size()) < MAX_ENTRIES) {
+    words.push_back(line);
+  }
+  f.close();
+  return words;
+}
+
+void LookupHistory::removeWord(const std::string& cachePath, const std::string& word) {
+  if (word.empty()) return;
+
+  auto existing = load(cachePath);
+
+  FsFile f;
+  if (!Storage.openFileForWrite("LKH", filePath(cachePath), f)) {
+    return;
+  }
+
+  for (const auto& w : existing) {
+    if (w != word) {
+      f.write(reinterpret_cast<const uint8_t*>(w.c_str()), w.size());
+      f.write(reinterpret_cast<const uint8_t*>("\n"), 1);
+    }
+  }
+  f.close();
+}
+
+void LookupHistory::addWord(const std::string& cachePath, const std::string& word) {
+  if (word.empty()) return;
+
+  // Check if already present
+  auto existing = load(cachePath);
+  if (std::any_of(existing.begin(), existing.end(), [&word](const std::string& w) { return w == word; })) return;
+
+  // Cap at max entries
+  if (static_cast<int>(existing.size()) >= MAX_ENTRIES) return;
+
+  FsFile f;
+  if (!Storage.openFileForWrite("LKH", filePath(cachePath), f)) {
+    return;
+  }
+
+  // Rewrite existing entries plus new one
+  for (const auto& w : existing) {
+    f.write(reinterpret_cast<const uint8_t*>(w.c_str()), w.size());
+    f.write(reinterpret_cast<const uint8_t*>("\n"), 1);
+  }
+  f.write(reinterpret_cast<const uint8_t*>(word.c_str()), word.size());
+  f.write(reinterpret_cast<const uint8_t*>("\n"), 1);
+  f.close();
+}

src/util/LookupHistory.h

@@ -0,0 +1,15 @@
+#pragma once
+#include <string>
+#include <vector>
+
+class LookupHistory {
+ public:
+  static std::vector<std::string> load(const std::string& cachePath);
+  static void addWord(const std::string& cachePath, const std::string& word);
+  static void removeWord(const std::string& cachePath, const std::string& word);
+  static bool hasHistory(const std::string& cachePath);
+
+ private:
+  static std::string filePath(const std::string& cachePath);
+  static constexpr int MAX_ENTRIES = 500;
+};