Fix image decode overflow and viewport clipping issues

Prevent integer overflow when validating large image dimensions by using 64-bit arithmetic. Add periodic yielding during JPEG/PNG decode to prevent watchdog timeouts on multi-second operations. Clamp image top margins to prevent full-height images from overflowing page bottom and failing bounds checks. Increase max source pixels from 3MP to 8MP to support high-resolution ebook covers while keeping decode times reasonable.

.claude/skills/README.md

@@ -0,0 +1,33 @@
+# CrossPoint Reader: Claude Code skills
+
+Project skills for Claude Code. Claude auto-discovers them and loads one when the
+task matches its `description`; you do not invoke them by hand. They encode how
+this project wants C/C++ written: the judgment calls and self-review gates that
+keep the firmware small, stable, and reviewable.
+
+These are written for capable agents, not beginners. They are principle- and
+decision-focused on purpose. They deliberately avoid line-number citations,
+which drift; they anchor on durable names (APIs, types, macros, files).
+
+This is separate from `.skills/SKILL.md`, the GitHub coding-agent guide that
+mirrors CLAUDE.md. CLAUDE.md stays the always-loaded rule set; these skills are
+the applied decision procedures that load on demand and add the judgment layer
+CLAUDE.md does not carry.
+
+| Skill | Loads when you are... |
+|---|---|
+| `heap-discipline` | allocating memory: new/malloc/vector/string, buffers, caches |
+| `control-flow-clarity` | writing branching logic, state flags, modes, if/else ladders |
+| `hal-and-abstractions` | touching storage, input, display, settings, i18n, rendering |
+| `scope-discipline` | adding a feature, activity, lib, setting, or dependency |
+| `refactor-for-review` | refactoring, cleaning up, or preparing a change for PR |
+
+Each skill ends with a self-review checklist Claude runs against its own diff
+before handing it back. Reviewing a PR? Those checklists double as a fast rubric.
+
+## Maintaining these
+
+Edit the `SKILL.md` under each directory. Keep them tight. Do not restate
+CLAUDE.md; add the judgment CLAUDE.md cannot afford to carry. Trigger quality
+lives in the `description` field: it must name the situations that should pull
+the skill in, in the words a contributor's task would use.

.claude/skills/control-flow-clarity/SKILL.md

@@ -0,0 +1,56 @@
+---
+name: control-flow-clarity
+description: Branching and state-modeling clarity in C/C++. Use when writing or refactoring logic that branches on discrete values: if/else-if ladders, status flags, mode or state ints, or anything that should be an enum plus an exhaustive switch. Covers enum class over magic ints, exhaustive switch over nested if, early-return guard clauses, table dispatch, and when each is the right call.
+---
+
+# Control-Flow Clarity
+
+The goal: a reviewer verifies correctness by reading, not by tracing. Branching
+that mirrors the problem's shape is self-evident; branching that encodes it in
+ad-hoc ints and nesting forces the reader to reconstruct intent.
+
+## Core moves
+
+- **Model a closed set of states/modes as an `enum class`, not ints or bools.**
+  A variable kept honest by a comment ("0 = hidden, 1 = showing, 2 = confirm")
+  is a latent bug. Make it an enum and the comment becomes the type.
+- **Dispatch on an enum with an exhaustive `switch`, no `default`.** This
+  codebase relies on it: omitting `default` lets the compiler flag the
+  unhandled case when someone adds an enum value. A `default:` that swallows the
+  unknown case throws that safety away. Add `default` only when "every other
+  value does nothing" is a deliberate, documented decision.
+- **Replace nested `if/else-if` ladders that branch on one discriminant with a
+  `switch`.** If each branch only maps input to a value, prefer a lookup table
+  (`static constexpr` array) over both.
+- **Prefer early-return guard clauses over nested success bodies.** Handle the
+  error/empty/skip cases first and return; keep the main path at the left
+  margin.
+
+## When NOT to switch
+
+- Branches test unrelated conditions, not one discriminant: a guarded `if`
+  sequence is honest; a switch would be forced.
+- Two outcomes on a genuine boolean: keep the `if`.
+- The discriminant is an open or unbounded set (arbitrary ints, strings): table
+  or map, not a switch.
+
+## Enum hygiene
+
+- `enum class` by default for type safety. Plain `enum` only when values must
+  implicitly convert (e.g. a value that doubles as a UI dropdown index), and
+  then give it a trailing `_COUNT` sentinel for safe bounds/iteration, matching
+  the existing settings enums.
+- Name the discriminant after what it selects, not its storage:
+  `Orientation orientation`, not `uint8_t mode`.
+- No magic numeric codes for states. If you write a comment mapping numbers to
+  meanings, you owe an enum.
+
+## Self-review
+
+- [ ] No int/bool standing in for a closed set of modes; it is an `enum class`.
+- [ ] Enum dispatch is an exhaustive `switch` with no catch-all `default` (or
+      the `default` is a documented deliberate choice).
+- [ ] No nested if/else-if ladder on a single discriminant that should be a
+      switch or a table.
+- [ ] Error/skip cases are early-return guards; the happy path is not buried.
+- [ ] No magic numbers where a named enum or `constexpr` would state the intent.

.claude/skills/hal-and-abstractions/SKILL.md

@@ -0,0 +1,59 @@
+---
+name: hal-and-abstractions
+description: Layering and abstraction discipline for the firmware. Use when touching storage, input, display, settings, i18n, or rendering, or any code that could reach into the SDK. Covers routing through the HAL (HalStorage / HalGPIO / HalDisplay) instead of raw SDK classes, MappedInputManager logical buttons instead of raw GPIO indices, UITheme/GUI for all rendering, the singleton macros, tr() for user-facing text, and where a new abstraction boundary belongs.
+---
+
+# HAL and Abstractions
+
+CLAUDE.md lists the HAL classes and the SdFat-concurrency reason they exist.
+This is when and how to route through them, and where to draw a new boundary.
+
+## Route through the layer, always
+
+- **SD card I/O:** `Storage` (HalStorage) and `HalFile`. Never `SdFat`,
+  `FsFile`, `SdSpiCard`, `FsBaseFile`, or `SDCardManager` directly. The HAL
+  serializes every SD access through one mutex; bypassing it races the SPI state
+  machine and panics FreeRTOS (CLAUDE.md has the failure mode). This is a
+  correctness boundary, not a style preference.
+- **Display:** `HalDisplay` over `EInkDisplay`. **Input:** `HalGPIO` over
+  `InputManager`.
+- **Rendering:** everything through the `GUI` macro (UITheme) and the renderer's
+  oriented metrics. No hardcoded fonts, colors, coordinates, or 800/480
+  literals; ask the renderer for width/height and use the oriented viewable
+  area.
+- **Input in activities:** `MappedInputManager::Button` logical enums
+  (`Button::Confirm`, `Button::PageForward`, ...). Never raw `HalGPIO::BTN_*`
+  indices outside `ButtonRemapActivity`. Logical buttons survive user remapping
+  and orientation; raw indices do not.
+- **Shared state:** the singleton macros (`SETTINGS`, `APP_STATE`, `GUI`,
+  `Storage`, `I18N`), not threaded pointers.
+
+## User-facing text
+
+Every string a user reads goes through `tr(STR_*)`. Add the key to the English
+YAML, regenerate with `scripts/gen_i18n.py`, then use the `StrId`. Log lines
+(`LOG_*`) stay hardcoded.
+
+## Drawing a new boundary
+
+When you need an SDK capability the HAL does not expose yet, **add the method to
+the HAL; do not reach around it.** The new method inherits the mutex, logging,
+and error contract the rest of the HAL carries. A one-off direct SDK call in an
+activity is exactly the layering violation the mutex discipline cannot tolerate.
+
+Keep abstractions thin. A wrapper that only renames an SDK call without adding
+the mutex, logging, or an error contract is dead weight. Add a layer only when
+it carries one of those contracts or hides a real implementation choice.
+
+## Self-review
+
+- [ ] No direct SdFat / FsFile / SDCardManager / EInkDisplay / InputManager use
+      outside `lib/hal`.
+- [ ] File access uses `HalFile`; no `.close()` on a local handle
+      (DESTRUCTOR_CLOSES_FILE); members closed in `onExit`.
+- [ ] Input uses `MappedInputManager::Button`, not raw `BTN_*` indices.
+- [ ] Rendering goes through GUI/UITheme and oriented metrics; no 800/480 or
+      hardcoded fonts/coords.
+- [ ] User-facing strings use `tr(STR_*)`; new keys added to YAML and
+      regenerated.
+- [ ] Any new SDK capability is exposed as a HAL method, not called inline.

.claude/skills/heap-discipline/SKILL.md

@@ -0,0 +1,65 @@
+---
+name: heap-discipline
+description: Memory allocation discipline for the ESP32-C3 (~380KB RAM, no PSRAM, single 48KB framebuffer). Use whenever writing or reviewing code that allocates: new / malloc / std::vector / std::string, buffers, caches, or anything held across a loop or an activity lifecycle. Covers makeUniqueNoThrow vs raw new/malloc, fragmentation avoidance, reserve-before-push_back, alloc-once-reuse, stack vs heap sizing, and the chunked grayscale buffer pattern.
+---
+
+# Heap Discipline (ESP32-C3)
+
+CLAUDE.md states the allocation rules. This is the procedure you run while
+writing the code and the gate you run before handing it back.
+
+The constraint that makes every call matter: ~380KB RAM, no PSRAM, one 48KB
+framebuffer. **Fragmentation, not total usage, is what kills this device.**
+Free-heap can read fine while the largest free block is too small for the next
+allocation. Optimize for not leaving holes, not just for using fewer bytes.
+
+## Allocation decision procedure
+
+Ask in order; stop at the first yes.
+
+1. **Stack?** Local, bounded, under ~256 bytes total: plain array/struct. No
+   heap, no fragmentation. Keep frames lean; the task stack is small.
+2. **Compile-time constant?** `static constexpr` lives in flash, costs zero DRAM.
+3. **Allocated once and reused for an activity's lifetime?** Allocate in
+   `onEnter`, hold in a member, release in `onExit`. Never per-frame, never
+   per-iteration.
+4. **Dynamic and fallible?** `makeUniqueNoThrow<T>(...)` /
+   `makeUniqueNoThrow<T[]>(n)` from `lib/Memory/Memory.h`. Null-check, `LOG_ERR`
+   with the size, return false. It frees on every exit path.
+5. **A C/SDK API takes ownership and frees it itself?** Only then raw
+   `new (std::nothrow)` / `malloc`, with a comment naming who frees it.
+
+Bare `new` / `new[]` is never correct here: under `-fno-exceptions` it calls
+`abort()` on OOM instead of returning null.
+
+## Fragmentation rules
+
+- `std::vector`: `reserve(n)` before any `push_back` loop. Each growth is
+  alloc-copy-free (three heap ops) and leaves a hole. Unknown n: estimate high.
+- No repeated `new`/`delete` or growing containers inside a loop or render path.
+  Hoist the allocation out of the loop.
+- Large contiguous blocks fragment worst. Full-screen-class buffers use the
+  chunked `storeBwBuffer` / `restoreBwBuffer` path in `GfxRenderer` so they
+  never demand one contiguous 48KB block. Reuse that path. Do not malloc a
+  second full-screen buffer.
+- `std::string` / Arduino `String`: acceptable on cold paths (file I/O, one-shot
+  setup). Banned on hot/render paths. Build text with a stack `char[]` +
+  `snprintf`; if a `std::string` is unavoidable, `reserve` it first.
+
+## Justify every allocation
+
+Per CLAUDE.md's evidence rule: when you add a heap allocation, state in one line
+why stack/static/reuse was rejected and the worst-case size. If you cannot name
+the size, you cannot budget it, and you should not allocate it.
+
+## Self-review before handoff
+
+- [ ] No bare `new`/`new[]`. Every fallible alloc is `makeUniqueNoThrow`, or a
+      raw alloc with an explicit owner comment.
+- [ ] Every allocation is null-checked with `LOG_ERR` before the error return.
+- [ ] No allocation inside a loop or render path that could be hoisted.
+- [ ] Every `push_back` loop has a preceding `reserve`.
+- [ ] Anything allocated in `onEnter` is released in `onExit`; member `HalFile`
+      closed there too.
+- [ ] No second full-screen buffer; grayscale uses store/restoreBwBuffer.
+- [ ] Each new allocation carries a one-line size + why-not-stack/static note.

.claude/skills/refactor-for-review/SKILL.md

@@ -0,0 +1,59 @@
+---
+name: refactor-for-review
+description: Producing small, single-concern, reviewable changes. Use when refactoring, cleaning up, restructuring, decomposing, or preparing a change for PR, especially in this multi-contributor AI-assisted codebase that is prone to sprawl diffs. Covers one-concern-per-commit, extracting helpers without widening scope, not bundling unrelated edits, decomposing oversized activities, comment hygiene, and a pre-handoff self-review checklist.
+---
+
+# Refactor for Review
+
+This is a multi-contributor, AI-assisted codebase, and the dominant failure mode
+is the sprawl diff: a one-line intent that touches thirty files. The goal is a
+change a reviewer can verify in one sitting. Cleaner structure that makes the
+next change easier is the win, not lines added.
+
+## One concern per change
+
+- A commit/PR does one thing. A bug fix is not also a rename is not also a
+  reformat. If you spot an unrelated improvement mid-change, leave it or capture
+  it separately; do not fold it in.
+- When the working tree has bundled two changes, separate them with the
+  copy-affected-files-aside, reset, re-apply one concern, restore the rest
+  pattern, not by committing the tangle.
+- Refactor and behavior change do not ride together. A pure refactor must not
+  alter behavior; a behavior change should not drag a refactor along. If both
+  are needed: two commits, refactor first.
+
+## Keep the diff narrow
+
+- Extract a helper to remove real duplication or to name a concept, not to chase
+  abstraction. Three-plus copies, or a block that needs a name to be understood:
+  extract. Two similar lines: leave them.
+- No "while I'm here" scope creep. A signature or type change that ripples to
+  many call sites is its own PR: map every caller first, update them in one
+  topological pass, and land it separately, not as a rider on a feature.
+- Match the surrounding code: comment density, naming, idiom. The diff should
+  read like the file, not like a different author.
+
+## Decompose oversized units
+
+An activity or function that has outgrown one screen of responsibility (multiple
+unrelated state machines, or a file far larger than its siblings) is a
+decomposition candidate. Extract a cohesive sub-responsibility into its own
+unit, as a standalone behavior-preserving refactor, verified on its own, never
+mixed into a feature change.
+
+## Comments earn their place
+
+Comments explain why: an invariant, a defense, a past incident, a non-obvious
+constraint. Never what the next line already says. Delete narration, phase-marker
+comments ("now we loop over..."), and restated function names. If a comment and
+the code it sits on say the same thing, the comment is the thing to cut.
+
+## Self-review before handoff
+
+- [ ] The change does exactly one thing; nothing unrelated rode along.
+- [ ] Refactor and behavior change are not mixed in one commit.
+- [ ] No "while I'm here" creep; rename/signature ripples are split out.
+- [ ] Extractions remove real duplication or name a real concept, not
+      speculative abstraction.
+- [ ] New comments say why, not what; no narration or phase markers.
+- [ ] A reviewer can understand the diff without running it.

.claude/skills/scope-discipline/SKILL.md

@@ -0,0 +1,54 @@
+---
+name: scope-discipline
+description: Feature-scope discipline for a dedicated e-reader (not a Swiss Army knife). Use when adding a feature, a new activity, a new lib, a setting, or a dependency, or when a request would grow the firmware's surface. Covers the SCOPE.md test, the RAM-cost vs reading-benefit gate, preferring no-code or existing-mechanism solutions, awareness of the existing activity surface, and how to push back on out-of-scope asks.
+---
+
+# Scope Discipline
+
+The mission: do one thing exceptionally well, focused reading on constrained
+hardware. `SCOPE.md` is the source of truth for what is in and out. Read it
+before adding surface. This is the gate to run before writing a new feature.
+
+## The gate
+
+Before adding a feature, activity, lib, setting, or dependency, answer in order:
+
+1. **Is it in `SCOPE.md`?** Explicitly out: interactive apps (notepad,
+   calculator, games), active connectivity (RSS, news, browser), media/audio
+   playback. If it is out, say so and stop.
+2. **Does it materially improve focused reading?** If the benefit is
+   "nice to have" or serves a different use case, it is out. This is not a PDA.
+3. **What does it cost in RAM and in the largest-free-block budget?** A feature
+   that adds steady-state RAM or a large transient allocation needs a reading
+   benefit that clearly outweighs it. Quantify with `firmware_size_history.py`
+   and `script_profile_mem.sh` rather than guessing.
+4. **Can it be done with no new code?** Prefer an existing activity, an existing
+   setting, or a doc over a new code path. The cheapest feature is the one
+   already built.
+
+If a request fails the gate, push back with the specific reason and the
+`SCOPE.md` basis, and offer the in-scope alternative. Make the call and say why;
+do not just hand over a menu.
+
+## Surface awareness
+
+The firmware already carries dozens of activities. Each new one is permanent
+RAM, permanent maintenance, and another thing every future refactor must not
+break. Default to extending an existing activity or setting before adding a new
+screen. New top-level surface needs a real justification, not "it would be
+convenient."
+
+## Settings are not free
+
+A new setting is a field to persist, migrate, validate, translate, and render,
+plus combinatorial test burden. Add one only when users genuinely need the
+choice; otherwise pick a sensible fixed default.
+
+## Self-review
+
+- [ ] Checked against `SCOPE.md`; not on the out-of-scope list.
+- [ ] Stated the concrete reading benefit, not a generic "useful."
+- [ ] Named the RAM/size cost (measured, not guessed) and why the benefit wins.
+- [ ] Checked whether an existing activity/setting/doc already covers it.
+- [ ] New setting (if any) is justified by a real user need, not added
+      "just in case."

.githooks/pre-commit

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# Run formatter from repository root regardless of current directory.
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+cd "${REPO_ROOT}"
+
+# Capture the files already staged for commit so we only re-stage those
+# paths after formatting.
+staged_files=()
+while IFS= read -r -d '' file; do
+  staged_files+=("${file}")
+done < <(git diff --cached --name-only -z --diff-filter=ACMR)
+
+# Intentionally format all currently modified tracked C/C++ files.
+# The helper handles no-op cases and exits 0 when nothing matches.
+echo "Running clang-format fix before commit..."
+./bin/clang-format-fix
+
+# Ensure formatting changes are included in the pending commit without
+# staging unrelated tracked modifications from other files in the
+# working tree.
+if ((${#staged_files[@]})); then
+  git add -- "${staged_files[@]}"
+fi

.github/FUNDING.yml

@@ -1,2 +1 @@
-github: [daveallie]
-ko_fi: daveallie
+custom: ["https://app.royalty.dev/crosspoint-reader/crosspoint-reader"]

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,13 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Scope or Roadmap Question (start here if unsure)
+    url: https://github.com/crosspoint-reader/crosspoint-reader/discussions
+    about: |
+      Not sure if your idea fits CrossPoint's scope? Start a Discussion before filing an issue.
+      See SCOPE.md and ROADMAP.md for what is in, out, and currently paused.
+  - name: Read the Scope document
+    url: https://github.com/crosspoint-reader/crosspoint-reader/blob/master/SCOPE.md
+    about: The authoritative list of what CrossPoint will and will not accept.
+  - name: Read the Roadmap
+    url: https://github.com/crosspoint-reader/crosspoint-reader/blob/master/ROADMAP.md
+    about: Current phase, what is being closed out, and what comes next.

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,80 @@
+name: Feature Request
+description: Propose a new feature, enhancement, or change to CrossPoint
+title: "Short, descriptive title of the request"
+labels: ["enhancement", "needs-scope-review"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to propose a change to CrossPoint!
+
+        **Before you continue, please read [SCOPE.md](../blob/master/SCOPE.md) and [ROADMAP.md](../blob/master/ROADMAP.md).**
+
+        CrossPoint is intentionally narrow. Most rejected proposals are rejected for scope reasons that are already
+        documented. The checklist below exists to save both of us time.
+
+        If you are not sure whether your idea fits, open a [Discussion](../../discussions) first instead of filing
+        this issue.
+
+  - type: checkboxes
+    id: scope-check
+    attributes:
+      label: Scope Self-Check (required)
+      description: Please confirm each of the following. If any are unchecked, your issue will likely be closed.
+      options:
+        - label: I have read SCOPE.md and ROADMAP.md.
+          required: true
+        - label: This is **not** a new theme or theming change (themes are temporarily closed pending the move to SD-loaded themes).
+          required: true
+        - label: This is **not** a new external network connector (sync engine, cloud storage, remote file access, OPDS extensions beyond what exists, or any new "talk to a server" feature).
+          required: true
+        - label: This is **not** an interactive app (game, calculator, notepad), writing/authoring tool, RSS/news/browser feature, media playback feature, or PDF rendering.
+          required: true
+        - label: The stock firmware does **not** already handle this well.
+          required: true
+        - label: No other popular CrossPoint fork already handles this well (or, if one does, I explain below why CrossPoint still needs it).
+          required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem this solves
+      description: What user-facing problem or reading-experience gap does this address? Be concrete.
+      placeholder: e.g., "When reading in landscape, paragraph breaks are inconsistent because..."
+    validations:
+      required: true
+
+  - type: textarea
+    id: stock-gap
+    attributes:
+      label: Why the stock firmware (and other forks) do not already solve this
+      description: Explain which existing solutions you checked and why they fall short. This is the core scope filter.
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposal
+    attributes:
+      label: Proposed change
+      description: A short description of what you would build or change. Focus on user impact; implementation details can come later.
+    validations:
+      required: true
+
+  - type: textarea
+    id: tradeoffs
+    attributes:
+      label: Memory / flash / complexity cost
+      description: |
+        CrossPoint runs on 380KB of RAM. Roughly how much DRAM, flash, or code complexity does this add?
+        "Don't know" is a valid answer, but please attempt an estimate.
+      placeholder: e.g., "Adds ~2KB flash for the new font tables, no DRAM impact at runtime."
+    validations:
+      required: false
+
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional context
+      description: Anything else relevant (links, screenshots, related discussions).
+    validations:
+      required: false

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,16 +3,34 @@
 * **What is the goal of this PR?** (e.g., Implements the new feature for file uploading.)
 * **What changes are included?**
 
+## Scope Check
+
+CrossPoint is intentionally narrow. See [SCOPE.md](../blob/master/SCOPE.md) and [ROADMAP.md](../blob/master/ROADMAP.md).
+Please confirm:
+
+- [ ] I have read SCOPE.md and ROADMAP.md.
+- [ ] This PR is **not** a new built-in theme (themes are temporarily closed pending the move to SD-loaded themes).
+- [ ] This PR is **not** a new external network connector (sync engine, cloud storage, remote file access, etc.).
+- [ ] This PR is **not** an interactive app, writing tool, RSS/news/browser, media playback, or PDF feature.
+- [ ] The stock firmware does not already handle this well, **and** no other popular CrossPoint fork already does
+      (or, if one does, I explain why CrossPoint still needs it below).
+- [ ] If this PR touches `freeink-sdk/`, `lib/hal/`, the bootloader, OTA, or recovery code, I have coordinated with
+      the relevant maintainer.
+
+**If this PR was opened against the previous (broader) scope and was already in flight under Phase 0, link the
+relevant Discussion or issue so reviewers can see the history.**
+
 ## Additional Context
 
-* Add any other information that might be helpful for the reviewer (e.g., performance implications, potential risks, 
+* Add any other information that might be helpful for the reviewer (e.g., performance implications, potential risks,
   specific areas to focus on).
+* Memory / flash impact, if known.
 
 ---
 
 ### AI Usage
 
-While CrossPoint doesn't have restrictions on AI tools in contributing, please be transparent about their usage as it 
+While CrossPoint doesn't have restrictions on AI tools in contributing, please be transparent about their usage as it
 helps set the right context for reviewers.
 
 Did you use AI tools to help write this code? _**< YES | PARTIALLY | NO >**_

.github/workflows/ci.yml

@@ -53,10 +53,18 @@ jobs:
       - name: Install PlatformIO Core
         run: uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.19.zip
 
+      - name: Cache PlatformIO packages
+        uses: actions/cache@v4
+        with:
+          path: ~/.platformio
+          key: pio-${{ runner.os }}-${{ hashFiles('platformio.ini') }}
+          restore-keys: pio-${{ runner.os }}-
+
       - name: Run cppcheck
         run: pio check --fail-on-defect low --fail-on-defect medium --fail-on-defect high
 
-  build:
+  build-default:
+    name: Build default
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
@@ -76,10 +84,17 @@ jobs:
       - name: Install PlatformIO Core
         run: uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.19.zip
 
-      - name: Build CrossPoint
+      - name: Cache PlatformIO packages
+        uses: actions/cache@v4
+        with:
+          path: ~/.platformio
+          key: pio-${{ runner.os }}-${{ hashFiles('platformio.ini') }}
+          restore-keys: pio-${{ runner.os }}-
+
+      - name: Build default firmware
         run: |
           set -euo pipefail
-          pio run | tee pio.log
+          pio run -e default | tee pio.log
 
       - name: Extract firmware stats
 
@@ -102,14 +117,89 @@ jobs:
           path: .pio/build/default/firmware.bin
           if-no-files-found: error
 
+  build-sticky:
+    name: Build sticky
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.14'
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+        with:
+          version: "latest"
+          enable-cache: false
+
+      - name: Install PlatformIO Core
+        run: uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.19.zip
+
+      - name: Cache PlatformIO packages
+        uses: actions/cache@v4
+        with:
+          path: ~/.platformio
+          key: pio-${{ runner.os }}-${{ hashFiles('platformio.ini') }}
+          restore-keys: pio-${{ runner.os }}-
+
+      - name: Build sticky firmware
+        run: |
+          set -euo pipefail
+          pio run -e sticky | tee pio.log
+
+      - name: Extract firmware stats
+        run: |
+          set -euo pipefail
+          ram_line="$(grep -E "RAM:\\s" -m1 pio.log || true)"
+          flash_line="$(grep -E "Flash:\\s" -m1 pio.log || true)"
+          echo "ram_line=${ram_line}" >> "$GITHUB_OUTPUT"
+          echo "flash_line=${flash_line}" >> "$GITHUB_OUTPUT"
+          {
+            echo "## Sticky firmware build stats"
+            if [ -n "$ram_line" ]; then echo "- ${ram_line}"; else echo "- RAM: not found"; fi
+            if [ -n "$flash_line" ]; then echo "- ${flash_line}"; else echo "- Flash: not found"; fi
+          } >> "$GITHUB_STEP_SUMMARY"
+
+  unit-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - name: Install build tools
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y cmake ninja-build
+
+      - name: Cache googletest source
+        uses: actions/cache@v4
+        with:
+          path: build/test/_deps/googletest-src
+          key: ${{ runner.os }}-googletest-${{ hashFiles('test/CMakeLists.txt') }}
+
+      - name: Configure
+        run: cmake -S test -B build/test -G Ninja -DCMAKE_BUILD_TYPE=Release
+
+      - name: Build
+        run: cmake --build build/test
+
+      - name: Run tests
+        run: ctest --test-dir build/test --output-on-failure -j
+
   # This job is used as the PR required actions check, allows for changes to other steps in the future without breaking
   # PR requirements.
   test-status:
     name: Test Status
     needs:
-      - build
+      - build-default
+      - build-sticky
       - clang-format
       - cppcheck
+      - unit-tests
     if: always()
     runs-on: ubuntu-latest
     steps:

.github/workflows/release-fonts.yml

@@ -0,0 +1,106 @@
+name: Build & Publish SD Card Fonts
+
+# Fonts change rarely — run manually when font sources or the conversion
+# pipeline are updated.  Publishes .cpfont files + fonts.json manifest as
+# GitHub Release assets on the crosspoint-fonts repo so font releases don't
+# clutter the firmware releases page.
+#
+# Requires a repository secret FONTS_REPO_TOKEN — a fine-grained PAT (or
+# classic PAT) with contents:write permission on the target fonts repo.
+on:
+  workflow_dispatch:
+
+env:
+  FONTS_REPO: crosspoint-reader/crosspoint-fonts
+
+jobs:
+  build-fonts:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.14'
+
+      - name: Install font tools
+        run: pip install freetype-py fonttools pyyaml
+
+      - name: Install system dependencies
+        run: sudo apt-get update && sudo apt-get install -y libfreetype6-dev
+
+      - name: Read version constants
+        id: versions
+        run: |
+          cd lib/EpdFont/scripts
+          echo "binary=$(python3 -c 'from cpfont_version import CPFONT_VERSION; print(CPFONT_VERSION)')" >> "$GITHUB_OUTPUT"
+          echo "metadata=$(python3 -c 'from cpfont_version import FONTS_MANIFEST_VERSION; print(FONTS_MANIFEST_VERSION)')" >> "$GITHUB_OUTPUT"
+
+      - name: Build SD card fonts
+        run: python3 lib/EpdFont/scripts/build-sd-fonts.py --clean --verbose -j 1
+
+      - name: Flatten output for release assets
+        run: |
+          mkdir -p dist
+          find lib/EpdFont/scripts/output -name '*.cpfont' -exec cp {} dist/ \;
+
+      - name: Compute release tags
+        id: tags
+        env:
+          GH_TOKEN: ${{ secrets.FONTS_REPO_TOKEN }}
+        run: |
+          BASE="sd-fonts-m${{ steps.versions.outputs.metadata }}-b${{ steps.versions.outputs.binary }}"
+          echo "base=$BASE" >> "$GITHUB_OUTPUT"
+
+          # Find the highest existing revision for this m/b pair
+          LAST=$(gh release list --repo "${{ env.FONTS_REPO }}" \
+            --json tagName --jq \
+            '[.[] | select(.tagName | startswith("'"${BASE}-r"'")) | .tagName | split("-r")[1] | tonumber] | max // 0')
+          NEXT=$((LAST + 1))
+          echo "revision=$NEXT" >> "$GITHUB_OUTPUT"
+          echo "versioned=${BASE}-r${NEXT}" >> "$GITHUB_OUTPUT"
+
+      - name: Generate manifest
+        run: |
+          python3 scripts/generate-font-manifest.py \
+            --input dist \
+            --base-url "https://github.com/${{ env.FONTS_REPO }}/releases/download/${{ steps.tags.outputs.base }}/" \
+            --output dist/fonts.json \
+            --descriptions-from lib/EpdFont/scripts/sd-fonts.yaml
+
+      - name: Publish versioned release to fonts repo
+        env:
+          GH_TOKEN: ${{ secrets.FONTS_REPO_TOKEN }}
+        run: |
+          VERSIONED="${{ steps.tags.outputs.versioned }}"
+          TITLE="SD Card Fonts (${VERSIONED#sd-fonts-})"
+
+          gh release create "$VERSIONED" dist/* \
+            --repo "${{ env.FONTS_REPO }}" \
+            --title "$TITLE" \
+            --notes "Pre-built \`.cpfont\` font files for CrossPoint Reader.
+
+          Download individual files or use **Settings > System > Manage Fonts** on the device.
+
+          See [SD Card Fonts documentation](https://github.com/${{ github.repository }}/blob/main/docs/sd-card-fonts.md) for details."
+
+      - name: Update stable tag for device downloads
+        env:
+          GH_TOKEN: ${{ secrets.FONTS_REPO_TOKEN }}
+        run: |
+          BASE="${{ steps.tags.outputs.base }}"
+
+          # Delete the old stable release for this m/b pair (the versioned releases are kept)
+          gh release delete "$BASE" --repo "${{ env.FONTS_REPO }}" --yes 2>/dev/null || true
+
+          gh release create "$BASE" dist/* \
+            --repo "${{ env.FONTS_REPO }}" \
+            --title "SD Card Fonts (${BASE#sd-fonts-})" \
+            --notes "Current font build for manifest v${{ steps.versions.outputs.metadata }}, binary format v${{ steps.versions.outputs.binary }}. Devices with this firmware version download from this release.
+
+          This is revision **${{ steps.tags.outputs.revision }}** — see [\`${{ steps.tags.outputs.versioned }}\`](https://github.com/${{ env.FONTS_REPO }}/releases/tag/${{ steps.tags.outputs.versioned }}) for the immutable copy.
+
+          Download individual files or use **Settings > System > Manage fonts** on the device."

.github/workflows/release.yml

@@ -1,40 +0,0 @@
-name: Compile Release
-on:
-  push:
-    tags:
-      - '*'
-
-jobs:
-  build-release:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6
-        with:
-          submodules: recursive
-
-      - uses: actions/setup-python@v6
-        with:
-          python-version: '3.14'
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@v7
-        with:
-          version: "latest"
-          enable-cache: false
-
-      - name: Install PlatformIO Core
-        run: uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.19.zip
-
-      - name: Build CrossPoint
-        run: pio run -e gh_release
-
-      - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: CrossPoint-${{ github.ref_name }}
-          path: |
-            .pio/build/gh_release/bootloader.bin
-            .pio/build/gh_release/firmware.bin
-            .pio/build/gh_release/firmware.elf
-            .pio/build/gh_release/firmware.map
-            .pio/build/gh_release/partitions.bin

.github/workflows/release_candidate.yml

@@ -25,6 +25,13 @@ jobs:
       - name: Install PlatformIO Core
         run: uv pip install --system -U https://github.com/pioarduino/platformio-core/archive/refs/tags/v6.1.19.zip
 
+      - name: Cache PlatformIO packages
+        uses: actions/cache@v4
+        with:
+          path: ~/.platformio
+          key: pio-${{ runner.os }}-${{ hashFiles('platformio.ini') }}
+          restore-keys: pio-${{ runner.os }}-
+
       - name: Extract env
         run: |
           echo "SHORT_SHA=${GITHUB_SHA::7}" >> $GITHUB_ENV

.gitignore

@@ -2,6 +2,8 @@
 .idea
 .DS_Store
 .vscode
+open-x4-sdk
+fs_
 lib/EpdFont/fontsrc
 lib/I18n/I18nKeys.h
 lib/I18n/I18nStrings.h
@@ -15,3 +17,18 @@ build
 .history/
 /.venv
 *.local*
+*.cpfont
+lib/EpdFont/scripts/downloaded_fonts/
+lib/EpdFont/scripts/instanced_fonts/
+lib/EpdFont/scripts/output/
+# Claude Code: share project skills with the team, keep local agent state
+# (worktrees, scheduled-task locks, settings.local, scout CLEANUP.md) out.
+.claude/*
+!.claude/skills/
+/managed_components
+/.dummy
+/CMakeLists.txt
+/dependencies.lock
+/sdkconfig.*
+sdkconfig.sticky
+flake.*

.gitmodules

@@ -1,3 +1,4 @@
-[submodule "open-x4-sdk"]
-	path = open-x4-sdk
-	url = https://github.com/open-x4-epaper/community-sdk.git
+[submodule "freeink-sdk"]
+	path = freeink-sdk
+	url = https://github.com/Free-Ink/freeink-sdk.git
+	branch = main

AGENTS.md

@@ -0,0 +1 @@
+/home/urit/Documents/CrossPoint/crosspoint-reader/.skills/SKILL.md

README.md

@@ -1,104 +1,196 @@
 # CrossPoint Reader
 
-Firmware for the **Xteink X4** e-paper display reader (unaffiliated with Xteink).
-Built using **PlatformIO** and targeting the **ESP32-C3** microcontroller.
+[![Fund contributors](https://img.shields.io/badge/%F0%9F%91%91_Fund_contributors-royalty.dev-BB953A?style=for-the-badge&labelColor=1a1a1a)](https://app.royalty.dev/crosspoint-reader/crosspoint-reader)
 
-CrossPoint Reader is a purpose-built firmware designed to be a drop-in, fully open-source replacement for the official 
-Xteink firmware. It aims to match or improve upon the standard EPUB reading experience.
+CrossPoint is open-source e-reader firmware - community-built, fully hackable, free forever. It's maintained by a growing community of developers and readers who believe your device should do what you want - not what a manufacturer decided for you.
 
-![](./docs/images/cover.jpg)
+**Now running on:** ESP32C3-based Xteink [X4](https://www.xteink.com/products/xteink-x4) and [X3](https://www.xteink.com/products/xteink-x3).
 
-## Motivation
+![CrossPoint Reader running on Xteink device](./docs/images/cover.jpg)
 
-E-paper devices are fantastic for reading, but most commercially available readers are closed systems with limited 
-customisation. The **Xteink X4** is an affordable, e-paper device, however the official firmware remains closed.
-CrossPoint exists partly as a fun side-project and partly to open up the ecosystem and truely unlock the device's
-potential.
+> 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.
 
-CrossPoint Reader aims to:
-* Provide a **fully open-source alternative** to the official firmware.
-* Offer a **document reader** capable of handling EPUB content on constrained hardware.
-* Support **customisable font, layout, and display** options.
-* Run purely on the **Xteink X4 hardware**.
+## What can CrossPoint do?
 
-This project is **not affiliated with Xteink**; it's built as a community project.
+- **Reader engine**: EPUB 2/3 rendering with embedded-style option, image handling, hyphenation, kerning, chapter navigation, footnotes, bookmarks, dictionary lookups ([StarDict](docs/dictionary.md)), go-to-percent, auto page turn, orientation control, focus reading, KOReader progress sync and more. 
 
-## Features & Usage
+- **Various formats**: native handling for `.epub`, `.xtc/.xtch`, `.txt`, and `.bmp`.
 
-- [x] EPUB parsing and rendering (EPUB 2 and EPUB 3)
-- [x] Image support within EPUB
-- [x] Saved reading position
-- [x] File explorer with file picker
-  - [x] Basic EPUB picker from root directory
-  - [x] Support nested folders
-  - [ ] EPUB picker with cover art
-- [x] Custom sleep screen
-  - [x] Cover sleep screen
-- [x] Wifi book upload
-- [x] Wifi OTA updates
-- [x] KOReader Sync integration for cross-device reading progress
-- [x] Configurable font, layout, and display options
-  - [ ] User provided fonts
-  - [ ] Full UTF support
-- [x] Screen rotation
+- **Screenshots.**
 
-Multi-language support: Read EPUBs in various languages, including English, Spanish, French, German, Italian, Portuguese, Russian, Ukrainian, Polish, Swedish, Norwegian, [and more](./USER_GUIDE.md#supported-languages).
+- **Custom fonts**: install your favorite fonts on the SD card.
 
-See [the user guide](./USER_GUIDE.md) for instructions on operating CrossPoint, including the
-[KOReader Sync quick setup](./USER_GUIDE.md#365-koreader-sync-quick-setup).
+- **Tilt page turn (X3 only)**.
 
-For more details about the scope of the project, see the [SCOPE.md](SCOPE.md) document.
+- **Library workflow**: folder browser, hidden-file toggle, long-press delete, recent books, SD-cache management.
 
-## Installing
+- **Wireless workflows**:
+  
+  - File transfer web UI
+  - EPUB Optimizer
+  - Web settings UI/API (edit many device settings from browser)
+  - WebSocket fast uploads
+  - WebDAV handler
+  - AP mode (hotspot) and STA mode (join existing Wi-Fi), both with QR helpers
+  - Calibre wireless connect flow
+  - OPDS browser with saved servers (up to 8), search, pagination, and direct download
+  - OTA update checks and installs from GitHub releases
 
-### Web (latest firmware)
+- **Customization**: multiple themes (Classic, Lyra, Lyra Extended, RoundedRaff), sleep screen modes, front/side button remapping, status bar controls, power-button behavior, refresh cadence, and more.
 
-1. Connect your Xteink X4 to your computer via USB-C and wake/unlock the device
-2. Go to https://xteink.dve.al/ and click "Flash CrossPoint firmware"
+- **Localization**: 24 UI languages and counting. RTL support.
 
-To revert back to the official firmware, you can flash the latest official firmware from https://xteink.dve.al/, or swap
-back to the other partition using the "Swap boot partition" button here https://xteink.dve.al/debug.
+### Coming soon:
 
-### Web (specific firmware version)
+- More themes.
 
-1. Connect your Xteink X4 to your computer via USB-C
-2. Download the `firmware.bin` file from the release of your choice via the [releases page](https://github.com/crosspoint-reader/crosspoint-reader/releases)
-3. Go to https://xteink.dve.al/ and flash the firmware file using the "OTA fast flash controls" section
+- Much more! stay tuned.
 
-To revert back to the official firmware, you can flash the latest official firmware from https://xteink.dve.al/, or swap
-back to the other partition using the "Swap boot partition" button here https://xteink.dve.al/debug.
+---
+
+## USB-locked devices (Xteink Unlocker)
+
+Some Xteink units purchased from third-party stores (e.g. AliExpress) ship with USB flashing locked from the factory.
+If your device is locked, you will need to use the **Xteink Unlocker** tool available at
+https://crosspointreader.com/#unlock-tool before you can flash CrossPoint.
+
+**You do not need this tool if you bought your device directly from xteink.com.** Those units are not locked.
+
+**Not sure if your device is locked?** Power it on, connect the USB-C cable, and try flashing via the web flasher first (see
+[Install firmware](#install-firmware) below). If the browser's serial device picker does not show your device, try a different
+USB port or browser before assuming the device is locked. Only reach for the unlocker if the device still doesn't appear.
+
+> ### ⚠️ WARNING: READ THIS BEFORE USING THE UNLOCKER ⚠️
+> 
+> **The only officially supported firmwares in the unlock tool are CrossPoint and CrossInk.**
+> 
+> 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**.
+
+## Install firmware
+
+### Web installer (recommended)
+
+1. Connect your device to your computer via USB-C and wake/unlock the device
+2. Go to https://crosspointreader.com/#flash-tools, select device (X3 or X4), and choose an official CrossPoint release.
+
+### Web installer (specific version)
+
+1. Connect your device to your computer via USB-C and wake/unlock the device
+2. Download a `firmware.bin` from [Releases](https://github.com/crosspoint-reader/crosspoint-reader/releases), local build, or continuous integration artifact.
+3. Go to https://crosspointreader.com/#flash-tools, select device (X3 or X4), click "Custom .bin" and upload a `firmware.bin`.
+
+### Revert to Official Firmware
+
+To revert to the official firmware, you can also flash the latest official firmware using https://crosspointreader.com/#flash-tools.
+
+### Command line
+
+1. Install [`esptool`](https://github.com/espressif/esptool):
+
+```bash
+pip install esptool
+```
+
+2. Download `firmware.bin` from the [releases page](https://github.com/crosspoint-reader/crosspoint-reader/releases).
+3. Connect your device via USB-C.
+4. Find the device port. On Linux, run `dmesg` after connecting. On macOS:
+
+```bash
+log stream --predicate 'subsystem == "com.apple.iokit"' --info
+```
+
+5. Flash:
+
+```bash
+esptool.py --chip esp32c3 --port /dev/ttyACM0 --baud 921600 write_flash 0x10000 /path/to/firmware.bin
+```
+
+Adjust `/dev/ttyACM0` to match your system.
 
 ### Manual
 
-See [Development](#development) below.
+See [Development quick start](#development-quick-start) below.
 
-## Development
+---
+
+## Custom SD-card fonts
+
+Convert your own TTF/OTF files into `.cpfont` files that load from the SD card. No firmware reflash is needed.
+
+1. Go to https://crosspointreader.com/fonts and open the "SD-card font builder" form.
+2. Upload up to four styles (regular, bold, italic, bold-italic), set the family name, point sizes, and Unicode range.
+3. Download the generated `.cpfont` files.
+4. Copy them to your SD card under `/fonts/YourFont/` (or `/.fonts/YourFont/` to hide the folder).
+5. Select the font on the device from the font settings.
+
+Conversion runs the firmware repo's `lib/EpdFont/scripts/fontconvert_sdcard.py` script unmodified, so output matches a local host build.
+
+---
+
+## Documentation
+
+- [User Guide](./USER_GUIDE.md)
+- [Web server usage](./docs/webserver.md)
+- [Web server endpoints](./docs/webserver-endpoints.md)
+- [Project scope](./SCOPE.md)
+- [Contributing docs](./docs/contributing/README.md)
+- [Touch and UI development](./docs/contributing/touch-and-ui.md) - FreeInkUI components for new screens, the touch bridge for existing ones, and build envs for the non-Xteink touch devices
+
+---
+
+## Development quick start
 
 ### Prerequisites
 
-* **PlatformIO Core** (`pio`) or **VS Code + PlatformIO IDE**
-* Python 3.8+
-* USB-C cable for flashing the ESP32-C3
-* Xteink X4
+- [pioarduino](https://github.com/pioarduino/pioarduino) or VS Code + pioarduino plugin
+- Python 3.8+
+- `clang-format` 21
+- USB-C cable supporting data transfer
 
-### Checking out the code
+### Setup
 
-CrossPoint uses PlatformIO for building and flashing the firmware. To get started, clone the repository:
-
-```
+```bash
 git clone --recursive https://github.com/crosspoint-reader/crosspoint-reader
+cd crosspoint-reader
 
-# Or, if you've already cloned without --recursive:
+# if cloned without --recursive:
 git submodule update --init --recursive
 ```
 
-### Flashing your device
+### Nix/NixOS
 
-Connect your Xteink X4 to your computer via USB-C and run the following command.
+Nix/NixOS users can enter the development shell with either `nix develop` (flakes) or `nix-shell`:
 
-```sh
+```bash
+nix develop -f nix
+# or
+nix-shell nix
+```
+
+To flash a connected ESP32-C3 device, enable PlatformIO's udev rules in your NixOS configuration:
+
+```nix
+services.udev.packages = with pkgs; [ platformio-core.udev ];
+```
+
+After rebuilding the system configuration, reconnect the device or reload udev rules.
+
+### Build / flash / monitor
+
+```bash
 pio run --target upload
 ```
+
+### Contributor pre-PR checks
+
+```bash
+./bin/clang-format-fix
+pio check -e default
+pio run -e default
+```
+
 ### Debugging
 
 After flashing the new features, it’s recommended to capture detailed logs from the serial port.
@@ -108,7 +200,9 @@ First, make sure all required Python packages are installed:
 ```python
 python3 -m pip install pyserial colorama matplotlib
 ```
-after that run the script:
+
+After that run the script:
+
 ```sh
 # For Linux
 # This was tested on Debian and should work on most Linux systems.
@@ -117,63 +211,77 @@ python3 scripts/debugging_monitor.py
 # For macOS
 python3 scripts/debugging_monitor.py /dev/cu.usbmodem2101
 ```
+
 Minor adjustments may be required for Windows.
 
-## Internals
-
-CrossPoint Reader is pretty aggressive about caching data down to the SD card to minimise RAM usage. The ESP32-C3 only
-has ~380KB of usable RAM, so we have to be careful. A lot of the decisions made in the design of the firmware were based
-on this constraint.
-
-### Data caching
-
-The first time chapters of a book are loaded, they are cached to the SD card. Subsequent loads are served from the 
-cache. This cache directory exists at `.crosspoint` on the SD card. The structure is as follows:
-
-
-```
-.crosspoint/
-├── epub_12471232/       # Each EPUB is cached to a subdirectory named `epub_<hash>`
-│   ├── progress.bin     # Stores reading progress (chapter, page, etc.)
-│   ├── cover.bmp        # Book cover image (once generated)
-│   ├── book.bin         # Book metadata (title, author, spine, table of contents, etc.)
-│   └── sections/        # All chapter data is stored in the sections subdirectory
-│       ├── 0.bin        # Chapter data (screen count, all text layout info, etc.)
-│       ├── 1.bin        #     files are named by their index in the spine
-│       └── ...
-│
-└── epub_189013891/
-```
-
-Deleting the `.crosspoint` directory will clear the entire cache. 
-
-Due the way it's currently implemented, the cache is not automatically cleared when a book is deleted and moving a book
-file will use a new cache directory, resetting the reading progress.
-
-For more details on the internal file structures, see the [file formats document](./docs/file-formats.md).
-
-## Contributing
-
-Contributions are very welcome!
-
-If you are new to the codebase, start with the [contributing docs](./docs/contributing/README.md).
-
-If you're looking for a way to help out, take a look at the [ideas discussion board](https://github.com/crosspoint-reader/crosspoint-reader/discussions/categories/ideas).
-If there's something there you'd like to work on, leave a comment so that we can avoid duplicated effort.
-
-Everyone here is a volunteer, so please be respectful and patient. For more details on our goverance and community 
-principles, please see [GOVERNANCE.md](GOVERNANCE.md).
-
-### To submit a contribution:
-
-1. Fork the repo
-2. Create a branch (`feature/dithering-improvement`)
-3. Make changes
-4. Submit a PR
-
 ---
 
-CrossPoint Reader is **not affiliated with Xteink or any manufacturer of the X4 hardware**.
+## Internals
 
-Huge shoutout to [**diy-esp32-epub-reader** by atomic14](https://github.com/atomic14/diy-esp32-epub-reader), which was a project I took a lot of inspiration from as I
-was making CrossPoint.
+CrossPoint Reader is pretty aggressive about caching data down to the SD card to minimise RAM usage. The ESP32-C3 only has ~380KB of usable RAM, so we have to be careful. A lot of the decisions made in the design of the firmware were based on this constraint.
+
+### Data caching
+
+The first time chapters of a book are loaded, they are cached to the SD card. Subsequent loads are served from the
+cache. This cache directory exists at `.crosspoint` on the SD card. The structure is as follows:
+
+```text
+.crosspoint/
+├── epub_<hash>/         # one directory per book, named by content hash
+│   ├── progress.bin     # reading position (chapter, page, etc.)
+│   ├── cover.bmp        # generated cover image
+│   ├── book.bin         # metadata: title, author, spine, TOC
+│   ├── css_rules.cache  # parsed CSS rule cache
+│   ├── img_*            # rendered image cache files
+│   └── sections/        # per-chapter layout cache
+│       ├── 0.bin
+│       ├── 1.bin
+│       └── ...
+├── settings.json        # device settings
+├── state.json           # resume/runtime state
+└── recent.json          # recent books list
+```
+
+Removing `/.crosspoint` clears all cached metadata and forces a full regeneration on next open. Book deletes, overwrites, and moves done through the firmware or web UI clear or re-key matching caches; manual SD-card edits may leave stale cache directories behind.
+
+For more details on the internal file structures, see the [file formats document](./docs/file-formats.md).
+
+---
+
+## Contributing
+
+Contributions are welcome. If you're new to the codebase, start with the [contributing docs](./docs/contributing/README.md). For things to work on, check the [ideas discussion board](https://github.com/crosspoint-reader/crosspoint-reader/discussions/categories/ideas) — leave a comment before starting so we don't duplicate effort.
+
+Everyone here is a volunteer, so please be respectful and patient. For governance and community expectations, see [GOVERNANCE.md](./GOVERNANCE.md).
+
+---
+
+## Community forks
+
+One of the best things about open source is that anyone can take the code in a different direction. If you need something outside CrossPoint's [scope](./SCOPE.md), check out the community forks:
+
+- [CrossInk](https://github.com/uxjulia/CrossInk) — Typography and reading tracking: Bionic Reading (bolds word stems to create fixation points), guide dots between words, improved paragraph indents, and replaces the default fonts with ChareInk/Lexend/Bitter.
+
+- [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.~~ (Unmaintained)
+
+- [crosspoint-reader-cjk](https://github.com/aBER0724/crosspoint-reader-cjk) — Purpose-built for Chinese, Japanese, and Korean reading.
+
+- [inx](https://github.com/obijuankenobiii/inx) — Completely reimagines the user interface with tabbed navigation.
+
+- ~~[PlusPoint](https://github.com/ngxson/pluspoint-reader) — custom JS apps support.~~ (Unmaintained)
+
+- [crosspoint-reader-papers3](https://github.com/juicecultus/crosspoint-reader-papers3) — Crosspoint port for M5Stack Paper S3. 
+
+- [t5s3-reader](https://github.com/ShallowGreen123/t5s3-reader) — Crosspoint port for LilyGo T5 ePaper S3 / T5S3 4.7-inch e-paper device.
+
+**Note:** Many of these features will make their way into CrossPoint over time. We maintain a slower pace to ensure rock-solid stability and squash bugs before they reach your device.
+
+Want to build your own device? Be sure to check out the [de-link](https://github.com/iandchasse/de-link) project.
+
+---
+
+CrossPoint Reader is **not affiliated with Xteink or any device manufacturer**.
+
+Huge shoutout to [diy-esp32-epub-reader](https://github.com/atomic14/diy-esp32-epub-reader), which inspired this project.