Add SD catalog as default EPUB container backend

Changes the container backend strategy to use SD catalog by default for all EPUBs. On first open or stale index, builds the catalog once by borrowing the framebuffer (which can be released since e-ink holds the loading popup image). Subsequent opens use the fast path with compact resident tables. Falls back to legacy in-RAM open if catalog build fails due to IoError or OOM.
Add catalog-backed book cover extraction support
2026-08-13 14:21:57 -07:00 · 2026-07-08 14:08:15 -04:00 · 2026-07-08 13:51:58 -04:00 · 2026-07-08 13:41:16 -04:00 · 2026-07-08 05:43:38 -04:00 · 2026-07-08 04:46:25 -04:00
244 changed files with 6432 additions and 93713 deletions
@@ -1,3 +1,4 @@
-[submodule "open-x4-sdk"]
-	path = open-x4-sdk
-	url = https://github.com/crosspoint-reader/community-sdk.git
+[submodule "freeink-sdk"]
+	path = freeink-sdk
+	url = https://github.com/Free-Ink/freeink-sdk.git
+	branch = main
@@ -7,7 +7,7 @@ Mission: Provide a lightweight, high-performance reading experience focused on E
 * Role: Senior Embedded Systems Engineer (ESP-IDF/Arduino-ESP32 specialized).
 * Primary Constraint: 380KB RAM is the hard ceiling. Stability is non-negotiable.
 * Evidence-Based Reasoning: Before proposing a change, you MUST cite the specific file path and line numbers that justify the modification.
-* Anti-Hallucination: Do not assume the existence of libraries or ESP-IDF functions. If you are unsure of an API's availability for the ESP32-C3 RISC-V target, check the open-x4-sdk or official docs first.
+* Anti-Hallucination: Do not assume the existence of libraries or ESP-IDF functions. If you are unsure of an API's availability for the ESP32-C3 RISC-V target, check the freeink-sdk source or the FreeInk SDK docs (https://freeink.org/llms.txt for an LLM-readable index) first.
 * No Unfounded Claims: Do not claim performance gains or memory savings without explaining the technical mechanism (e.g., DRAM vs IRAM usage).
 * Resource Justification: You must justify any new heap allocation (new, malloc, std::vector) or explain why a stack/static alternative was rejected.
 * Verification: After suggesting a fix, instruct the user on how to verify it (e.g., monitoring heap via Serial or checking a specific cache file).
@@ -127,7 +127,7 @@ These flags in `platformio.ini` fundamentally affect firmware behavior:
  * lib/hal/: Hardware Abstraction Layer (HalDisplay, HalGPIO, HalStorage)
  * lib/I18n/: Internationalization (translations in `translations/*.yaml`, generated string tables)
 * src/activities/: UI logic using the Activity Lifecycle (onEnter, loop, onExit)
-* open-x4-sdk/: Low-level SDK (EInkDisplay, InputManager, BatteryMonitor, SDCardManager)
+* freeink-sdk/: Low-level SDK (EInkDisplay, InputManager, BatteryMonitor, SDCardManager)
 * .crosspoint/: SD-based binary cache for EPUB metadata and pre-rendered layout sections

 ### Hardware Abstraction Layer (HAL)
@@ -8,6 +8,8 @@ CrossPoint is open-source e-reader firmware - community-built, fully hackable, f

 ![CrossPoint Reader running on Xteink device](./docs/images/cover.jpg)

+> If you're planning to buy an Xteink device, consider purchasing an **X3/X4 Developer Edition** through https://crosspointreader.com. CrossPoint receives a small share of each sale, helping fund development costs.
+
 ## What can CrossPoint do?

 - **Reader engine**: EPUB 2/3 rendering with embedded-style option, image handling, hyphenation, kerning, chapter navigation, footnotes, bookmarks, go-to-percent, auto page turn, orientation control, focus reading, KOReader progress sync and more. 
@@ -67,10 +69,6 @@ USB port or browser before assuming the device is locked. Only reach for the unl
 > Flashing any other firmware on a USB-locked device may **permanently brick the device** or leave it **permanently
 > stuck on that firmware with no recovery path**. Once USB flashing is re-locked, your only way back is via OTA, and if
 > the firmware you flashed doesn't support OTA, **there is no way out**.
-> 
-> **The Papyrix fork has removed OTA update support from its code.** If you flash Papyrix onto a
-> USB-locked unit, you will have **zero update or recovery path** and will be stuck on it forever. **Do not flash
-> Papyrix (or any other unsupported firmware) on a locked device.**

 ## Install firmware

@@ -249,7 +247,7 @@ One of the best things about open source is that anyone can take the code in a d

 - [papyrix-reader](https://github.com/bigbag/papyrix-reader) — Adds FB2 and MD format support. Actively maintained with Arabic script support. Custom themes via SD card.

- [crosspet](https://github.com/trilwu/crosspet) — A Vietnamese fork that adds a Tamagotchi-style virtual chicken that grows based on your reading milestones (pages read, streaks, care). Also: Flashcards, Weather, Pomodoro timer, and mini-games.
+- ~~[crosspet](https://github.com/trilwu/crosspet) — A Vietnamese fork that adds a Tamagotchi-style virtual chicken that grows based on your reading milestones (pages read, streaks, care). Also: Flashcards, Weather, Pomodoro timer, and mini-games.~~ (Unmaintained)

 - [crosspoint-reader-cjk](https://github.com/aBER0724/crosspoint-reader-cjk) — Purpose-built for Chinese, Japanese, and Korean reading.

@@ -5,6 +5,7 @@ Welcome to the **CrossPoint** firmware. This guide outlines the hardware control
 - [CrossPoint User Guide](#crosspoint-user-guide)
  - [1. Hardware Overview](#1-hardware-overview)
    - [Button Layout](#button-layout)
+    - [Taking a Screenshot](#taking-a-screenshot)
  - [2. Power \& Startup](#2-power--startup)
    - [Power On / Off](#power-on--off)
    - [First Launch](#first-launch)
@@ -14,7 +15,11 @@ Welcome to the **CrossPoint** firmware. This guide outlines the hardware control
    - [3.3 Browse Files Screen](#33-browse-files-screen)
    - [3.4 Recent Books Screen](#34-recent-books-screen)
    - [3.5 File Transfer Screen](#35-file-transfer-screen)
-      - [3.5.1 Calibre Wireless Transfers](#351-calibre-wireless-transfers)
+    - [3.5.1 Calibre Wireless Transfers](#351-calibre-wireless-transfers)
+      - [Installing the Plugin in Calibre](#installing-the-plugin-in-calibre)
+      - [Configuring the CrossPoint Plugin in Calibre](#configuring-the-crosspoint-plugin-in-calibre)
+      - [Uploading Books](#uploading-books)
+      - [Removing a Book](#removing-a-book)
    - [3.6 Settings](#36-settings)
      - [3.6.1 Display](#361-display)
      - [3.6.2 Reader](#362-reader)
@@ -23,21 +28,25 @@ Welcome to the **CrossPoint** firmware. This guide outlines the hardware control
      - [3.6.5 OPDS Servers (Multiple Libraries)](#365-opds-servers-multiple-libraries)
      - [3.6.6 Web Settings (Wi-Fi + OPDS)](#366-web-settings-wi-fi--opds)
      - [3.6.7 KOReader Sync Quick Setup](#367-koreader-sync-quick-setup)
+        - [Option A: Free Public Server (`sync.koreader.rocks`)](#option-a-free-public-server-synckoreaderrocks)
+        - [Option B: Self-Hosted Server (Docker Compose)](#option-b-self-hosted-server-docker-compose)
    - [3.7 Sleep Screen](#37-sleep-screen)
+      - [Cover settings](#cover-settings)
+      - [Custom images](#custom-images)
    - [3.8 Custom Fonts (SD Card)](#38-custom-fonts-sd-card)
  - [4. Reading Mode](#4-reading-mode)
-      - [Page Turning](#page-turning)
-      - [Chapter Navigation](#chapter-navigation)
-      - [Auto Page Turn](#auto-page-turn)
-      - [Tilt Page Turn (X3 only)](#tilt-page-turn-x3-only)
-      - [Footnote Navigation](#footnote-navigation)
-      - [System Navigation](#system-navigation)
-      - [Supported Languages](#supported-languages)
+    - [Page Turning](#page-turning)
+    - [Chapter Navigation](#chapter-navigation)
+    - [Auto Page Turn](#auto-page-turn)
+    - [Tilt Page Turn (X3 only)](#tilt-page-turn-x3-only)
+    - [Footnote Navigation](#footnote-navigation)
+    - [System Navigation](#system-navigation)
+    - [Supported Languages](#supported-languages)
  - [5. Reader Menu](#5-reader-menu)
-      - [5.1 Chapter Selection](#51-chapter-selection)
-      - [5.2 Bookmarks](#52-bookmarks)
-  - [6. Current Limitations & Roadmap](#6-current-limitations--roadmap)
-  - [7. Troubleshooting Issues & Escaping Bootloop](#7-troubleshooting-issues--escaping-bootloop)
+    - [5.1 Chapter Selection](#51-chapter-selection)
+    - [5.2 Bookmarks](#52-bookmarks)
+  - [6. Current Limitations \& Roadmap](#6-current-limitations--roadmap)
+  - [7. Troubleshooting Issues \& Escaping Bootloop](#7-troubleshooting-issues--escaping-bootloop)

 ## 1. Hardware Overview

@@ -122,19 +131,43 @@ A **Wi-Fi signal strength indicator** (dBm) is displayed on-screen during joined

 CrossPoint supports sending books from Calibre using the CrossPoint Reader device plugin.

-1. Install the plugin in Calibre:
-   
-   - Head to https://github.com/crosspoint-reader/calibre-plugins/releases to download the latest version of the crosspoint_reader plugin.
-   
-   - Download the zip file.
-   
-   - Open Calibre → Preferences → Plugins → Load plugin from file → Select the zip file.
+#### Installing the Plugin in Calibre

-2. On the device: File Transfer -> Calibre Wireless, then join a network.
+If you don't already have the plugin installed:

-3. Make sure your computer is on the same Wi-Fi network.
+1. Head to https://github.com/crosspoint-reader/calibre-plugins/releases to download the latest version of the crosspoint_reader plugin.
+2. Download the zip file.
+3. Open Calibre → Preferences → Plugins → Load plugin from file → Select the zip file.
+4. Restart Calibre.

-4. In Calibre, click "Send to device" to transfer books.
+#### Configuring the CrossPoint Plugin in Calibre
+1. In Calibre select Preferences.
+2. In the Preferences dialog select Plugins.
+3. In Plugins search for "crosspoint".
+4. Click on "Customize plugin".
+5. Update the value for "Host" to match the IP for your device.
+6. Leave the other settings as they are.
+7. [optional] Modify the "Upload path" to point to a subfolder other than the root "/" folder. Enter this as a path relative to the root folder. Example: `/mybooks`
+8. Restart Calibre.
+
+<img width="420" height="385" alt="Image" src="https://github.com/user-attachments/assets/01fc7e33-a9a7-48ba-9e26-2e68d1f9daec" />
+
+#### Uploading Books
+
+To upload a book using the CrossPoint plugin in Calibre:
+
+1. On the device: File Transfer -> Calibre Wireless, then join a network.
+2. Select one or more books.
+3. Right-click on that selection.
+4. Select "Send to Device" > "Send to main memory"
+
+The CrossPoint plugin will connect to your device, create a folder for the book's author in the root folder (or the folder you configured for the plugin), then copy the book into that folder.
+
+<img width="783" height="310" alt="Image" src="https://github.com/user-attachments/assets/741b0909-2e1d-4f16-8af0-2c43fbda5ce6" />
+
+#### Removing a Book
+
+Books cannot be removed from your device through Calibre. Use the web interface instead.

 ### 3.6 Settings

@@ -150,6 +183,7 @@ The Settings screen allows you to configure the device's behavior. There are a f
  - "Cover" - The book cover image (Note: this is experimental and may not work as expected)
  - "None" - A blank screen
  - "Cover + Custom" - The book cover image while actively reading, falls back to "Custom" behavior otherwise
+  - "Quick resume" - The text of the last page read will be displayed on the sleep screen and a moon icon is shown on the edge of the screen. Waking up the device will return to the same page of the opened book. This is useful for quickly resuming reading without waiting for the device to fully wake up and load the book.

 - **Sleep Screen Cover Mode**: How to display the book cover when "Cover" sleep screen is selected:
  
@@ -162,6 +196,8 @@ The Settings screen allows you to configure the device's behavior. There are a f
  - "Contrast" - The image will be displayed as a black & white image without grayscale conversion
  - "Inverted" - The image will be inverted as in white & black and will be displayed without grayscale conversion

+- **Quick Resume on Timeout**: Whether to enable the "Quick Resume" sleep screen when the device goes to sleep due to inactivity (System > Time to Sleep). This is useful for quickly resuming reading without waiting for the device to fully wake up and load the book. This overwrites the Sleep Screen Cover Mode when enabled.
+
 - **Status Bar**: Configure the status bar displayed while reading:
  
  - "None" - No status bar
@@ -4,7 +4,7 @@

 .DESCRIPTION
    Formats all C/C++ source and header files in the repository, excluding
-    generated, vendored, and build directories (open-x4-sdk, builtinFonts,
+    generated, vendored, and build directories (freeink-sdk, builtinFonts,
    hyphenation tries, uzlib, .pio, *.generated.h).

    The clang-format binary path is resolved once and cached in
@@ -92,7 +92,7 @@ function Resolve-ClangFormat {
 $clangFormat = Resolve-ClangFormat

 $exclude = @(
-    'open-x4-sdk'
+    'freeink-sdk'
    'lib\EpdFont\builtinFonts'
    'lib\Epub\Epub\hyphenation\generated'
    'lib\uzlib'
@@ -8,7 +8,7 @@ At a high level, it is firmware that uses an activity-driven application archite

 ```mermaid
 graph TD
-    A[Hardware: ESP32-C3 + SD + E-ink + Buttons] --> B[open-x4-sdk]
+    A[Hardware: ESP32-C3 + SD + E-ink + Buttons] --> B[freeink-sdk]
    B --> C[lib/hal wrappers]
    C --> D[src/main.cpp runtime loop]
    D --> E[Activities layer]
@@ -195,10 +195,10 @@ When editing related source assets, regenerate via normal build steps/scripts.
 - `src/`: app orchestration, settings/state, and activity implementations
 - `src/network/`: web server and OTA/update networking
 - `src/components/`: theming and shared UI components
- `lib/hal/`: hardware abstraction wrappers around open-x4-sdk
+- `lib/hal/`: hardware abstraction wrappers around freeink-sdk
 - `lib/Epub/`: EPUB parser, layout, CSS handling, and hyphenation
 - `lib/`: supporting libraries (fonts, text, filesystem helpers, etc.)
- `open-x4-sdk/`: hardware SDK submodule (display, input, storage, battery)
+- `freeink-sdk/`: hardware SDK submodule (display, input, storage, battery). Docs: https://freeink.org/docs
 - `docs/`: user and technical documentation

 ## Embedded constraints that shape design
@@ -90,13 +90,13 @@ if (parsedSize != fileSize) {

 ## `section.bin`

-### Version 25
+### Version 29

 Each file in `sections/*.bin` stores one laid-out spine section. The header is
 also the cache-busting key: if any layout-affecting setting differs from the
 current reader settings, the section is discarded and rebuilt.

-Version 25 includes:
+Version 29 includes:

 - cache-busting fields for paragraph alignment, hyphenation, embedded CSS,
  image rendering mode, and Focus Reading
@@ -105,6 +105,12 @@ Version 25 includes:
 - paragraph and list-item LUTs used by KOReader sync page refinement
 - optional per-word Focus Reading split metadata
 - per-page footnote entries
+- serialized word style bits for underline, strikethrough, superscript, and
+  subscript
+- flat TextBlock word storage (v29): per-word arrays plus one shared
+  NUL-terminated text blob, replacing v28's length-prefixed word strings. The
+  on-disk order mirrors the in-RAM arena so the firmware reads a whole block
+  payload with a single allocation and a single SD read

 ImHex pattern:

@@ -113,7 +119,7 @@ import std.mem;
 import std.string;
 import std.core;

-#define EXPECTED_VERSION 25
+#define EXPECTED_VERSION 29
 #define MAX_STRING_LENGTH 65535
 #define FOOTNOTE_NUMBER_LEN 32
 #define FOOTNOTE_HREF_LEN 96
@@ -174,14 +180,20 @@ struct BlockStyle {

 struct TextBlock {
    u16 wordCount;
-    String words[wordCount];
-    s16 wordXPos[wordCount];
-    WordStyle wordStyle[wordCount];
-
    u8 hasFocus;
-    if (hasFocus != 0) {
-        u8 wordFocusBoundary[wordCount] [[comment("UTF-8 byte boundary between bold prefix and suffix")]];
-        u16 wordFocusSuffixX[wordCount] [[comment("Suffix x offset from word start")]];
+    u16 textBytes [[comment("Total size of text[], including one NUL per word")]];
+
+    if (wordCount > 0) {
+        u16 textOff[wordCount] [[comment("Byte offset of word i's text within text[]")]];
+        s16 wordXPos[wordCount];
+        if (hasFocus != 0) {
+            u16 wordFocusSuffixX[wordCount] [[comment("Suffix x offset from word start")]];
+        }
+        WordStyle wordStyle[wordCount];
+        if (hasFocus != 0) {
+            u8 wordFocusBoundary[wordCount] [[comment("UTF-8 byte boundary between bold prefix and suffix")]];
+        }
+        char text[textBytes] [[comment("All words back to back, each NUL-terminated")]];
    }

    BlockStyle blockStyle;
@@ -154,6 +154,21 @@ uint32_t EpdFont::applyLigatures(uint32_t cp, const char*& text) const {
  return cp;
 }

+bool EpdFont::hasGlyph(const uint32_t cp) const {
+  const int count = data->intervalCount;
+  if (count > 0) {
+    const EpdUnicodeInterval* intervals = data->intervals;
+    const auto it =
+        std::upper_bound(intervals, intervals + count, cp,
+                         [](uint32_t value, const EpdUnicodeInterval& interval) { return value < interval.first; });
+    if (it != intervals && cp <= (it - 1)->last) return true;
+  }
+  if (data->glyphMissHandler) {
+    return data->glyphMissHandler(data->glyphMissCtx, cp) != nullptr;
+  }
+  return false;
+}
+
 const EpdGlyph* EpdFont::getGlyph(const uint32_t cp) const {
  const int count = data->intervalCount;
  if (count == 0 && !data->glyphMissHandler) return nullptr;
@@ -12,6 +12,12 @@ class EpdFont {

  const EpdGlyph* getGlyph(uint32_t cp) const;

+  /// True when the font actually provides `cp` (interval table or on-demand
+  /// SD load) — unlike getGlyph(), never satisfied by the replacement glyph.
+  /// Used by layout shaping to decide whether a substitution (ligature,
+  /// Arabic presentation form) can really be drawn.
+  bool hasGlyph(uint32_t cp) const;
+
  /// Returns the kerning adjustment (4.4 fixed-point in pixels) between two codepoints.
  /// Returns 0 if no kerning data exists for the pair.
  int8_t getKerning(uint32_t leftCp, uint32_t rightCp) const;
@@ -1,7 +1,7 @@
 #include "EpdFontFamily.h"

 const EpdFont* EpdFontFamily::getFont(const Style style) const {
-  // Extract font style bits (ignore UNDERLINE bit for font selection)
+  // Extract font style bits; render-time overlay bits do not affect font selection.
  const bool hasBold = (style & BOLD) != 0;
  const bool hasItalic = (style & ITALIC) != 0;

@@ -28,10 +28,16 @@ const EpdGlyph* EpdFontFamily::getGlyph(const uint32_t cp, const Style style) co
  return getFont(style)->getGlyph(cp);
 }

+bool EpdFontFamily::hasGlyph(const uint32_t cp, const Style style) const { return getFont(style)->hasGlyph(cp); }
+
 int8_t EpdFontFamily::getKerning(const uint32_t leftCp, const uint32_t rightCp, const Style style) const {
  return getFont(style)->getKerning(leftCp, rightCp);
 }

+uint32_t EpdFontFamily::getLigature(const uint32_t leftCp, const uint32_t rightCp, const Style style) const {
+  return getFont(style)->getLigature(leftCp, rightCp);
+}
+
 uint32_t EpdFontFamily::applyLigatures(const uint32_t cp, const char*& text, const Style style) const {
  return getFont(style)->applyLigatures(cp, text);
 }
@@ -17,6 +17,7 @@ class EpdFontFamily {
    SUP = 16,           // superscript: glyph scaled 50%, raised ~40% of ascender
    SUB = 32,           // subscript: glyph scaled 50%, lowered ~25% of ascender
  };
+  static constexpr uint8_t TEXT_DECORATION_MASK = static_cast<uint8_t>(UNDERLINE | STRIKETHROUGH);

  explicit EpdFontFamily(const EpdFont* regular, const EpdFont* bold = nullptr, const EpdFont* italic = nullptr,
                         const EpdFont* boldItalic = nullptr)
@@ -25,8 +26,13 @@ class EpdFontFamily {
  void getTextDimensions(const char* string, int* w, int* h, Style style = REGULAR) const;
  const EpdFontData* getData(Style style = REGULAR) const;
  const EpdGlyph* getGlyph(uint32_t cp, Style style = REGULAR) const;
+  bool hasGlyph(uint32_t cp, Style style = REGULAR) const;
  int8_t getKerning(uint32_t leftCp, uint32_t rightCp, Style style = REGULAR) const;
+  uint32_t getLigature(uint32_t leftCp, uint32_t rightCp, Style style = REGULAR) const;
  uint32_t applyLigatures(uint32_t cp, const char*& text, Style style = REGULAR) const;
+  static constexpr bool hasTextDecoration(const Style style) {
+    return (static_cast<uint8_t>(style) & TEXT_DECORATION_MASK) != 0;
+  }

 private:
  const EpdFont* regular;
@@ -33,12 +33,24 @@ void FontDecompressor::freePageBuffer() {
 }

 void FontDecompressor::freeHotGroup() {
-  hotGroup.clear();
-  hotGroup.shrink_to_fit();
+  free(hotGroup);
+  hotGroup = nullptr;
+  hotGroupCapacity = 0;
  hotGroupFont = nullptr;
  hotGroupIndex = UINT16_MAX;
-  hotGlyphBuf.clear();
-  hotGlyphBuf.shrink_to_fit();
+  free(hotGlyphBuf);
+  hotGlyphBuf = nullptr;
+  hotGlyphBufCapacity = 0;
+}
+
+bool FontDecompressor::ensureCapacity(uint8_t*& buf, uint32_t& capacity, uint32_t needed) {
+  if (capacity >= needed) return true;
+  // Grow-only, free-then-malloc: every caller fully rewrites the buffer after a grow, so the
+  // old contents are dead -- freeing first gives the allocator its best shot on a tight heap.
+  free(buf);
+  buf = static_cast<uint8_t*>(malloc(needed));  // owned by FontDecompressor, freed in freeHotGroup()
+  capacity = buf ? needed : 0;
+  return buf != nullptr;
 }

 uint16_t FontDecompressor::getGroupIndex(const EpdFontData* fontData, uint32_t glyphIndex) {
@@ -170,24 +182,20 @@ const uint8_t* FontDecompressor::getBitmap(const EpdFontData* fontData, const Ep
  }

  // Check if hot group already has this group decompressed — if not, decompress it
-  if (!(!hotGroup.empty() && hotGroupFont == fontData && hotGroupIndex == groupIndex)) {
+  if (!(hotGroup != nullptr && hotGroupFont == fontData && hotGroupIndex == groupIndex)) {
    stats.cacheMisses++;
    const EpdFontGroup& group = fontData->groups[groupIndex];

-    hotGroup.resize(group.uncompressedSize);
-    if (hotGroup.empty()) {
+    // ensureCapacity may free the buffer, so the cached-group identity dies with it either way.
+    hotGroupFont = nullptr;
+    hotGroupIndex = UINT16_MAX;
+    if (!ensureCapacity(hotGroup, hotGroupCapacity, group.uncompressedSize)) {
      LOG_ERR("FDC", "Failed to allocate %u bytes for hot group %u", group.uncompressedSize, groupIndex);
-      hotGroupFont = nullptr;
-      hotGroupIndex = UINT16_MAX;
      stats.getBitmapTimeUs += micros() - tStart;
      return nullptr;
    }

-    if (!decompressGroup(fontData, groupIndex, hotGroup.data(), group.uncompressedSize)) {
-      hotGroup.clear();
-      hotGroup.shrink_to_fit();
-      hotGroupFont = nullptr;
-      hotGroupIndex = UINT16_MAX;
+    if (!decompressGroup(fontData, groupIndex, hotGroup, group.uncompressedSize)) {
      stats.getBitmapTimeUs += micros() - tStart;
      return nullptr;
    }
@@ -200,18 +208,16 @@ const uint8_t* FontDecompressor::getBitmap(const EpdFontData* fontData, const Ep
  }

  // Compact just the requested glyph from byte-aligned data into scratch buffer
-  if (glyph->dataLength > hotGlyphBuf.size()) {
-    hotGlyphBuf.resize(glyph->dataLength);
-  }
-  if (hotGlyphBuf.empty()) {
+  if (!ensureCapacity(hotGlyphBuf, hotGlyphBufCapacity, glyph->dataLength)) {
+    LOG_ERR("FDC", "Failed to allocate %u bytes for glyph scratch", (unsigned)glyph->dataLength);
    stats.getBitmapTimeUs += micros() - tStart;
    return nullptr;
  }

  uint32_t alignedOff = getAlignedOffset(fontData, groupIndex, glyphIndex);
-  compactSingleGlyph(&hotGroup[alignedOff], hotGlyphBuf.data(), glyph->width, glyph->height);
+  compactSingleGlyph(&hotGroup[alignedOff], hotGlyphBuf, glyph->width, glyph->height);
  stats.getBitmapTimeUs += micros() - tStart;
-  return hotGlyphBuf.data();
+  return hotGlyphBuf;
 }

 // --- Prewarm: pre-decompress glyph bitmaps for a page of text ---
@@ -2,8 +2,6 @@

 #include <InflateReader.h>

-#include <vector>
-
 #include "EpdFontData.h"

 class FontDecompressor {
@@ -67,13 +65,22 @@ class FontDecompressor {

  // Hot group: last decompressed group (byte-aligned) for non-prewarmed fallback path.
  // Kept in byte-aligned format; individual glyphs are compacted on demand into hotGlyphBuf.
+  // Nothrow high-water malloc buffers, NOT std::vector: getBitmap() runs on the render path,
+  // and under -fno-exceptions a vector resize that hits OOM abort()s the firmware instead of
+  // failing (field crash: hotGroup.resize() -> std::bad_alloc -> abort with ~11 KB free).
+  // ensureCapacity() returns false on OOM so the caller can skip the glyph gracefully.
  const EpdFontData* hotGroupFont = nullptr;
  uint16_t hotGroupIndex = UINT16_MAX;
-  std::vector<uint8_t> hotGroup;
+  uint8_t* hotGroup = nullptr;  // owned; freed in freeHotGroup()/dtor
+  uint32_t hotGroupCapacity = 0;

  // Scratch buffer for compacting a single glyph from the hot group.
-  // Valid until the next getBitmap() call.
-  std::vector<uint8_t> hotGlyphBuf;
+  // Valid until the next getBitmap() call. Same ownership/OOM contract as hotGroup.
+  uint8_t* hotGlyphBuf = nullptr;
+  uint32_t hotGlyphBufCapacity = 0;
+
+  // Grow (never shrink) an owned buffer to at least `needed` bytes; false on OOM, buffer freed.
+  static bool ensureCapacity(uint8_t*& buf, uint32_t& capacity, uint32_t needed);

  void freePageBuffer();
  void freeHotGroup();
@@ -1061,6 +1061,28 @@ void SdCardFont::mergeIntoAdvanceTable(uint8_t styleIdx, const AdvanceEntry* sor
  advanceTableSize_[styleIdx] = k;
 }

+bool SdCardFont::hasGlyphMeta(uint8_t styleIdx, uint32_t codepoint) const {
+  styleIdx &= (MAX_STYLES - 1);
+  const PerStyle& s = styles_[styleIdx];
+  if (!loaded_ || !s.present) return false;
+  return findGlobalGlyphIndex(s, codepoint) >= 0;
+}
+
+uint16_t SdCardFont::ensureAdvance(uint8_t styleIdx, uint32_t codepoint) {
+  styleIdx &= (MAX_STYLES - 1);
+  if (!loaded_ || !styles_[styleIdx].present) return 0;
+  const uint16_t cached = getAdvance(codepoint, styleIdx);
+  if (cached != 0) return cached;
+  // 0 is either "not in table" or a genuine zero-width glyph; only pay the
+  // SD read when the resident interval table says the glyph exists.
+  if (findGlobalGlyphIndex(styles_[styleIdx], codepoint) < 0) return 0;
+  uint32_t cp = codepoint;
+  fetchAdvancesForCodepoints(&cp, 1, static_cast<uint8_t>(1u << styleIdx));
+  return getAdvance(codepoint, styleIdx);
+}
+
+uint8_t SdCardFont::styleIdxFromMissCtx(void* ctx) { return static_cast<OverflowContext*>(ctx)->styleIdx; }
+
 bool SdCardFont::hasAdvanceTable() const {
  for (uint8_t i = 0; i < MAX_STYLES; i++) {
    if (advanceTable_[i]) return true;
@@ -55,6 +55,23 @@ class SdCardFont {
  // Returns the 12.4 fixed-point advance, or 0 if not found.
  uint16_t getAdvance(uint32_t codepoint, uint8_t style) const;

+  // Layout-side metric access — the per-glyph path CpFontAdapter uses while
+  // the FreeInkBook engine measures a chapter. Neither touches bitmap data:
+  // going through getGlyph() would stream every occurrence's bitmap through
+  // the 8-slot overflow ring (one SD read per character — a crawling build).
+  //
+  // hasGlyphMeta answers existence from the resident interval table (no I/O).
+  bool hasGlyphMeta(uint8_t styleIdx, uint32_t codepoint) const;
+  // ensureAdvance returns the 12.4 fixed-point advanceX, fetching the glyph
+  // METADATA from SD once on a miss and merging it into the persistent
+  // advance table (so each unique codepoint costs one small read per
+  // session). Returns 0 when the style lacks the codepoint.
+  uint16_t ensureAdvance(uint8_t styleIdx, uint32_t codepoint);
+
+  // Recover the style index from an EpdFontData::glyphMissCtx (see
+  // fromMissCtx below for recovering the SdCardFont itself).
+  static uint8_t styleIdxFromMissCtx(void* ctx);
+
  // Returns true if advance table is populated for at least one style.
  bool hasAdvanceTable() const;

@@ -33,6 +33,7 @@ import sys
 import tempfile
 import threading
 import time
+import socket
 import urllib.request
 from concurrent.futures import ProcessPoolExecutor, as_completed
 from pathlib import Path
@@ -49,17 +50,44 @@ INSTANCE_DIR = SCRIPT_DIR / "instanced_fonts"
 DEFAULT_FALLBACK_FONT = EPDFONTS_DIR / "builtinFonts/source/NotoSans/NotoSans-Regular.ttf"


-def download_font(url: str, dest: Path) -> Path:
-    """Download a font file if not already cached. Returns the local path."""
+_orig_getaddrinfo = socket.getaddrinfo
+
+
+def _ipv4_only_getaddrinfo(*args, **kwargs):
+    """getaddrinfo variant that drops AAAA records (IPv4 only)."""
+    return [ai for ai in _orig_getaddrinfo(*args, **kwargs) if ai[0] == socket.AF_INET]
+
+
+def download_font(url: str, dest: Path, retries: int = 3) -> Path:
+    """Download a font file if not already cached. Returns the local path.
+
+    Some sources (e.g. mirrors.ctan.org) are round-robin redirectors that land
+    on a different mirror each request; a mirror may advertise an IPv6 address a
+    host without an IPv6 route cannot reach ([Errno 101] Network is unreachable).
+    Retry on failure, forcing IPv4 resolution after the first attempt.
+    """
    if dest.exists():
        return dest
    dest.parent.mkdir(parents=True, exist_ok=True)
    print(f"  Downloading {dest.name}...")
-    try:
-        urllib.request.urlretrieve(url, dest)
-    except Exception as e:
-        dest.unlink(missing_ok=True)
-        raise RuntimeError(f"Failed to download {url}: {e}") from e
+    last_err = None
+    for attempt in range(1, retries + 1):
+        force_ipv4 = attempt > 1
+        if force_ipv4:
+            socket.getaddrinfo = _ipv4_only_getaddrinfo
+        try:
+            urllib.request.urlretrieve(url, dest)
+            break
+        except Exception as e:  # noqa: BLE001 - reported via RuntimeError below
+            last_err = e
+            dest.unlink(missing_ok=True)
+            if attempt < retries:
+                print(f"  Attempt {attempt} failed ({e}); retrying (IPv4-only)...")
+        finally:
+            if force_ipv4:
+                socket.getaddrinfo = _orig_getaddrinfo
+    else:
+        raise RuntimeError(f"Failed to download {url}: {last_err}") from last_err
    size_kb = dest.stat().st_size / 1024
    print(f"  Downloaded {dest.name} ({size_kb:.0f} KB)")
    return dest
@@ -132,7 +132,16 @@ families:
      bold:       {url: "https://raw.githubusercontent.com/impallari/Libre-Baskerville/master/fonts/ttf/LibreBaskerville-Bold.ttf"}
      italic:     {url: "https://raw.githubusercontent.com/impallari/Libre-Baskerville/master/fonts/ttf/LibreBaskerville-Italic.ttf"}
      bolditalic: {url: "https://raw.githubusercontent.com/impallari/Libre-Baskerville/master/fonts/ttf/LibreBaskerville-BoldItalic.ttf"}
-    
+
+  - name: Vollkorn
+    description: "A serif for bread and butter use by Friedrich Althausen (Latin, Greek, Cyrillic)"
+    intervals: latin-ext,greek,cyrillic
+    sizes: [12, 14, 16, 18]
+    styles:
+      regular:    {url: "https://raw.githubusercontent.com/google/fonts/main/ofl/vollkorn/Vollkorn%5Bwght%5D.ttf", variable: {wght: 400}}
+      bold:       {url: "https://raw.githubusercontent.com/google/fonts/main/ofl/vollkorn/Vollkorn%5Bwght%5D.ttf", variable: {wght: 700}}
+      italic:     {url: "https://raw.githubusercontent.com/google/fonts/main/ofl/vollkorn/Vollkorn-Italic%5Bwght%5D.ttf", variable: {wght: 400}}
+      bolditalic: {url: "https://raw.githubusercontent.com/google/fonts/main/ofl/vollkorn/Vollkorn-Italic%5Bwght%5D.ttf", variable: {wght: 700}}

  # ── Sans-serif ─────────────────────────────────────────────────────────

@@ -1,77 +0,0 @@
-#pragma once
-
-#include <Print.h>
-
-#include <memory>
-#include <string>
-#include <unordered_map>
-#include <vector>
-
-#include "Epub/BookMetadataCache.h"
-#include "Epub/css/CssParser.h"
-
-class ZipFile;
-
-class Epub {
-  // the ncx file (EPUB 2)
-  std::string tocNcxItem;
-  // the nav file (EPUB 3)
-  std::string tocNavItem;
-  // where is the EPUBfile?
-  std::string filepath;
-  // the base path for items in the EPUB file
-  std::string contentBasePath;
-  // Uniq cache key based on filepath
-  std::string cachePath;
-  // Spine and TOC cache
-  std::unique_ptr<BookMetadataCache> bookMetadataCache;
-  // CSS parser for styling
-  std::unique_ptr<CssParser> cssParser;
-  // CSS files
-  std::vector<std::string> cssFiles;
-
-  bool findContentOpfFile(std::string* contentOpfFile) const;
-  bool parseContentOpf(BookMetadataCache::BookMetadata& bookMetadata, bool writeSpineEntries = true);
-  bool parseTocNcxFile() const;
-  bool parseTocNavFile() const;
-  void discoverCssFilesFromZip();
-  void parseCssFiles() const;
-
- public:
-  explicit Epub(std::string filepath, const std::string& cacheDir) : filepath(std::move(filepath)) {
-    // create a cache key based on the filepath
-    cachePath = cacheDir + "/epub_" + std::to_string(std::hash<std::string>{}(this->filepath));
-  }
-  ~Epub() = default;
-  std::string& getBasePath() { return contentBasePath; }
-  bool load(bool buildIfMissing = true, bool skipLoadingCss = false);
-  bool clearCache() const;
-  void setupCacheDir() const;
-  const std::string& getCachePath() const;
-  const std::string& getPath() const;
-  const std::string& getTitle() const;
-  const std::string& getAuthor() const;
-  const std::string& getLanguage() const;
-  std::string getCoverBmpPath(bool cropped = false) const;
-  bool generateCoverBmp(bool cropped = false) const;
-  std::string getThumbBmpPath() const;
-  std::string getThumbBmpPath(int height) const;
-  bool generateThumbBmp(int height) const;
-  uint8_t* readItemContentsToBytes(const std::string& itemHref, size_t* size = nullptr,
-                                   bool trailingNullByte = false) const;
-  bool readItemContentsToStream(const std::string& itemHref, Print& out, size_t chunkSize) const;
-  bool getItemSize(const std::string& itemHref, size_t* size) const;
-  BookMetadataCache::SpineEntry getSpineItem(int spineIndex) const;
-  BookMetadataCache::TocEntry getTocItem(int tocIndex) const;
-  int getSpineItemsCount() const;
-  int getTocItemsCount() const;
-  int getSpineIndexForTocIndex(int tocIndex) const;
-  int getTocIndexForSpineIndex(int spineIndex) const;
-  size_t getCumulativeSpineItemSize(int spineIndex) const;
-  int getSpineIndexForTextReference() const;
-
-  size_t getBookSize() const;
-  float calculateProgress(int currentSpineIndex, float currentSpineRead) const;
-  CssParser* getCssParser() const { return cssParser.get(); }
-  int resolveHrefToSpineIndex(const std::string& href) const;
-};