diff --git a/.agents/skills/build-cadmus-native/SKILL.md b/.agents/skills/build-cadmus-native/SKILL.md
index 58845f4a..9cba1d9e 100644
--- a/.agents/skills/build-cadmus-native/SKILL.md
+++ b/.agents/skills/build-cadmus-native/SKILL.md
@@ -29,14 +29,17 @@ it when documentation sources change.
 
 ## One-time setup
 
-### Download runtime assets (optional)
+### Runtime assets
+
+**Required for Kobo builds** — run both before `cargo xtask build-kobo`:
 
 ```bash
 cargo xtask download-assets
+cargo xtask download-fonts
 ```
 
-Pulls static assets (fonts, icons, etc.) from the latest GitHub release. Not
-strictly required for compilation, but the emulator and some tests expect them.
+`download-assets` pulls Plato runtime directories (`bin/`, `resources/`,
+`hyphenation-patterns/`). `download-fonts` assembles the `fonts/`.
 
 Native dependencies (MuPDF, libwebp, and the C wrapper) are now built
 automatically by `build.rs` when you run any Cargo command that compiles
diff --git a/.github/actions/build-kobo/action.yml b/.github/actions/build-kobo/action.yml
index a2bea6fd..a3b108d1 100644
--- a/.github/actions/build-kobo/action.yml
+++ b/.github/actions/build-kobo/action.yml
@@ -49,6 +49,11 @@ runs:
     - name: Cache Plato static assets
       uses: ./.github/actions/cache-assets
 
+    - name: Cache bundled fonts
+      uses: ./.github/actions/cache-fonts
+      with:
+        gh-token: ${{ inputs.gh-token }}
+
     - name: Install system packages
       uses: ./.github/actions/apt
 
diff --git a/.github/actions/cache-fonts/action.yml b/.github/actions/cache-fonts/action.yml
new file mode 100644
index 00000000..225870f5
--- /dev/null
+++ b/.github/actions/cache-fonts/action.yml
@@ -0,0 +1,56 @@
+name: Cache bundled fonts
+description: >
+  Restore or save the assembled fonts/ directory. The cache key incorporates
+  pinned release versions from download_fonts.rs and the gitlink SHAs of the
+  Noto and Google font submodules so the key changes when any font source
+  moves. On cache miss, downloads fonts via cargo xtask download-fonts.
+
+  Defaults to restore-only. Pass `mode: save` in the cache-warmup job to
+  write a fresh cache.
+
+inputs:
+  gh-token:
+    description: "GitHub token for downloading release assets"
+    required: true
+  mode:
+    description: "`restore` (default) or `save` (read-write)"
+    required: false
+    default: restore
+
+outputs:
+  cache-hit:
+    description: "Whether a matching cache entry was found"
+    value: ${{ steps.save.outputs.cache-hit || steps.restore.outputs.cache-hit }}
+
+runs:
+  using: composite
+  steps:
+    - name: Compute font submodule hash
+      id: font-submodules
+      shell: bash
+      run: |
+        sha=$(git ls-tree HEAD thirdparty/noto-fonts thirdparty/google-fonts | sha256sum | cut -c1-12)
+        echo "hash=$sha" >> "$GITHUB_OUTPUT"
+
+    - name: Restore bundled fonts cache
+      if: inputs.mode == 'restore'
+      id: restore
+      uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: fonts/
+        key: fonts-${{ hashFiles('xtask/src/tasks/download_fonts/**') }}-${{ steps.font-submodules.outputs.hash }}
+
+    - name: Save bundled fonts cache
+      if: inputs.mode == 'save'
+      id: save
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: fonts/
+        key: fonts-${{ hashFiles('xtask/src/tasks/download_fonts/**') }}-${{ steps.font-submodules.outputs.hash }}
+
+    - name: Download bundled fonts
+      if: steps.restore.outputs.cache-hit != 'true' && steps.save.outputs.cache-hit != 'true'
+      shell: bash
+      env:
+        GH_TOKEN: ${{ inputs.gh-token }}
+      run: cargo xtask download-fonts
diff --git a/.github/workflows/cargo.yml b/.github/workflows/cargo.yml
index f8f77eab..e902e56b 100644
--- a/.github/workflows/cargo.yml
+++ b/.github/workflows/cargo.yml
@@ -43,6 +43,7 @@ jobs:
               - '.github/actions/build-kobo/**'
               - '.github/actions/build-docs-epub/**'
               - '.github/actions/cargo-cache/**'
+              - '.github/actions/cache-fonts/**'
               - '.github/actions/install-doc-tools/**'
               - 'build-scripts/**'
               - '.gitmodules'
@@ -186,6 +187,11 @@ jobs:
         if: steps.cargo-llvm-cov-cache.outputs.cache-hit != 'true'
         uses: taiki-e/install-action@9458fed45835344deb5e69e06e831be047c96abf # cargo-llvm-cov
 
+      - name: Cache bundled fonts
+        uses: ./.github/actions/cache-fonts
+        with:
+          mode: save
+          gh-token: ${{ secrets.GITHUB_TOKEN }}
       - name: Download documentation EPUB
         if: steps.cache.outputs.cache-hit != 'true'
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
@@ -361,6 +367,11 @@ jobs:
         if: runner.os == 'macOS'
         run: brew install sdl2 freetype harfbuzz openjpeg jpeg-turbo libpng jbig2dec gumbo-parser djvulibre pkg-config
 
+      - name: Restore bundled fonts
+        uses: ./.github/actions/cache-fonts
+        with:
+          gh-token: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Restore shared cargo cache
         uses: ./.github/actions/cargo-cache
         with:
diff --git a/.gitignore b/.gitignore
index ef27cb96..27727aab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@
 /css/*-user.css
 /hyphenation-patterns
 /dictionaries
+/fonts
 /dist
 /bundle
 docs/book/
diff --git a/.gitmodules b/.gitmodules
index f82768a8..ba675a3c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -54,3 +54,13 @@
 	path = thirdparty/mdbook-i18n-helpers
 	url = https://github.com/OGKevin/mdbook-i18n-helpers.git
 	branch = ogkevin/push/qsonrqyvotux
+[submodule "thirdparty/noto-fonts"]
+	path = thirdparty/noto-fonts
+	url = https://github.com/notofonts/noto-fonts
+	branch = v20201206-phase3
+	shallow = true
+[submodule "thirdparty/google-fonts"]
+	path = thirdparty/google-fonts
+	url = https://github.com/google/fonts
+	branch = main
+	shallow = true
diff --git a/contrib/Settings-sample.toml b/contrib/Settings-sample.toml
index 7567c248..1513a424 100644
--- a/contrib/Settings-sample.toml
+++ b/contrib/Settings-sample.toml
@@ -166,7 +166,7 @@ corner-width = 0.4
 # Note: this does not exist by default.
 font-path = "/mnt/onboard/fonts"
 # The default serif font.
-font-family = "Libertinus Serif"
+font-family = "Libron"
 # The default, minimum and maximum font sizes, in points.
 font-size = 11.0
 min-font-size = 5.5
diff --git a/crates/build-deps/src/markers.rs b/crates/build-deps/src/markers.rs
index 6074fae6..7acff102 100644
--- a/crates/build-deps/src/markers.rs
+++ b/crates/build-deps/src/markers.rs
@@ -90,9 +90,27 @@ pub fn is_built(root: &Path, dir: &Path, submodule_path: &str) -> bool {
 pub fn mark_built(root: &Path, dir: &Path, name: &str, submodule_path: &str) -> Result<()> {
     let hash = submodule_commit(root, submodule_path)
         .with_context(|| format!("failed to resolve submodule commit for {submodule_path}"))?;
-    let marker_path = dir.join(BUILT_MARKER);
-    std::fs::write(&marker_path, hash.as_bytes())
-        .with_context(|| format!("failed to write build marker for {name}"))?;
+    mark_version(dir, name, &hash)
+}
+
+/// Returns `true` when `dir` has a `.built` marker whose content matches
+/// `expected`.
+///
+/// Use this for pinned release tags or other version strings when there is no
+/// submodule gitlink to compare against.
+pub fn is_version_current(dir: &Path, expected: &str) -> bool {
+    std::fs::read_to_string(built_marker_path(dir)).is_ok_and(|stored| stored.trim() == expected)
+}
+
+/// Write a `.built` marker in `dir` with `version`, recording that `name`
+/// is up to date at that revision.
+///
+/// # Errors
+///
+/// Returns an error if the marker file cannot be written.
+pub fn mark_version(dir: &Path, name: &str, version: &str) -> Result<()> {
+    std::fs::write(built_marker_path(dir), version.as_bytes())
+        .with_context(|| format!("failed to write version marker for {name}"))?;
     Ok(())
 }
 
diff --git a/crates/core/src/document/html/engine.rs b/crates/core/src/document/html/engine.rs
index 1ddda9ce..5c1281dd 100644
--- a/crates/core/src/document/html/engine.rs
+++ b/crates/core/src/document/html/engine.rs
@@ -34,7 +34,7 @@ use paragraph_breaker::{standard_fit, total_fit};
 use percent_encoding::percent_decode_str;
 use septem::Roman;
 use std::convert::TryFrom;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use xi_unicode::LineBreakIterator;
 
@@ -102,16 +102,18 @@ impl Engine {
         self.hyphenation_patterns.clone().unwrap()
     }
 
+    /// Lazily loads [`build_default_reader_fonts`] from the install `fonts/` directory.
     #[inline]
     pub fn load_fonts(&mut self) {
         if self.fonts.is_none() {
-            self.fonts = build_fonts(&self.install_dir).ok();
+            self.fonts = build_default_reader_fonts(&self.install_dir).ok();
         }
     }
 
+    /// Lazily loads [`build_default_reader_fonts`] from `root_dir/fonts/`.
     pub fn load_fonts_from(&mut self, root_dir: std::path::PathBuf) {
         if self.fonts.is_none() {
-            self.fonts = build_fonts(&root_dir).ok();
+            self.fonts = build_default_reader_fonts(&root_dir).ok();
         }
     }
 
@@ -142,8 +144,14 @@ impl Engine {
         self.text_align = text_align;
     }
 
+    /// Sets the reading font from `family_name`, searching bundled install fonts
+    /// before `search_path`.
     pub fn set_font_family(&mut self, family_name: &str, search_path: &str) {
-        if let Ok(serif_family) = FontFamily::from_name(family_name, search_path) {
+        let install_fonts = self.install_dir.join("fonts");
+        if let Ok(serif_family) = FontFamily::from_name_in_paths(
+            family_name,
+            &[install_fonts.as_path(), Path::new(search_path)],
+        ) {
             self.load_fonts();
             if let Some(fonts) = self.fonts.as_mut() {
                 fonts.serif = serif_family;
@@ -2461,21 +2469,26 @@ fn format_list_prefix(kind: ListStyleType, index: usize) -> Option<String> {
     }
 }
 
-fn build_fonts(install_dir: &std::path::Path) -> Result<Fonts, Error> {
+/// Loads bundled default stacks for CSS generic font families (`serif`,
+/// `sans-serif`, `monospace`, `cursive`, `fantasy`) used by the HTML reader.
+///
+/// User-selected reading fonts replace only the `serif` stack via
+/// [`Engine::set_font_family`].
+fn build_default_reader_fonts(install_dir: &std::path::Path) -> Result<Fonts, Error> {
     let opener = FontOpener::new()?;
     let font_path = |name: &str| -> std::path::PathBuf { install_dir.join("fonts").join(name) };
     let mut fonts = Fonts {
         serif: FontFamily {
-            regular: opener.open(font_path("LibertinusSerif-Regular.otf").as_path())?,
-            italic: opener.open(font_path("LibertinusSerif-Italic.otf").as_path())?,
-            bold: opener.open(font_path("LibertinusSerif-Bold.otf").as_path())?,
-            bold_italic: opener.open(font_path("LibertinusSerif-BoldItalic.otf").as_path())?,
+            regular: opener.open(font_path("Libron-Regular.ttf").as_path())?,
+            italic: opener.open(font_path("Libron-Italic.ttf").as_path())?,
+            bold: opener.open(font_path("Libron-Bold.ttf").as_path())?,
+            bold_italic: opener.open(font_path("Libron-BoldItalic.ttf").as_path())?,
         },
         sans_serif: FontFamily {
-            regular: opener.open(font_path("NotoSans-Regular.ttf").as_path())?,
-            italic: opener.open(font_path("NotoSans-Italic.ttf").as_path())?,
-            bold: opener.open(font_path("NotoSans-Bold.ttf").as_path())?,
-            bold_italic: opener.open(font_path("NotoSans-BoldItalic.ttf").as_path())?,
+            regular: opener.open(font_path("NV_Jost-Regular.ttf").as_path())?,
+            italic: opener.open(font_path("NV_Jost-Italic.ttf").as_path())?,
+            bold: opener.open(font_path("NV_Jost-Bold.ttf").as_path())?,
+            bold_italic: opener.open(font_path("NV_Jost-BoldItalic.ttf").as_path())?,
         },
         monospace: FontFamily {
             regular: opener.open(font_path("SourceCodeVariable-Roman.otf").as_path())?,
diff --git a/crates/core/src/font/mod.rs b/crates/core/src/font/mod.rs
index 75733e82..c6cc356d 100644
--- a/crates/core/src/font/mod.rs
+++ b/crates/core/src/font/mod.rs
@@ -596,15 +596,39 @@ pub fn family_names<P: AsRef<Path>>(search_path: P) -> Result<BTreeSet<String>,
 }
 
 impl FontFamily {
+    /// Resolves `family_name` by searching `search_paths` in order.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error when `search_paths` is empty or the family cannot be
+    /// found in any path.
+    pub fn from_name_in_paths(
+        family_name: &str,
+        search_paths: &[impl AsRef<Path>],
+    ) -> Result<FontFamily, Error> {
+        let mut last_err = None;
+        for path in search_paths {
+            match Self::from_name_in_directory(family_name, path.as_ref()) {
+                Ok(family) => return Ok(family),
+                Err(err) => last_err = Some(err),
+            }
+        }
+        Err(last_err.unwrap_or_else(|| format_err!("no font search paths provided")))
+    }
+
     pub fn from_name<P: AsRef<Path>>(
         family_name: &str,
         search_path: P,
     ) -> Result<FontFamily, Error> {
+        Self::from_name_in_paths(family_name, &[search_path.as_ref()])
+    }
+
+    fn from_name_in_directory(family_name: &str, search_path: &Path) -> Result<FontFamily, Error> {
         let opener = FontOpener::new()?;
         let glob = Glob::new("**/*.[ot]tf")?.compile_matcher();
         let mut styles = FxHashMap::default();
 
-        for entry in WalkDir::new(search_path.as_ref())
+        for entry in WalkDir::new(search_path)
             .min_depth(1)
             .into_iter()
             .filter_entry(|e| !e.is_hidden())
@@ -2777,3 +2801,38 @@ impl From<FtError> for FreetypeError {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::path::PathBuf;
+
+    fn workspace_fonts_dir() -> PathBuf {
+        PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("../../fonts")
+    }
+
+    #[test]
+    fn from_name_in_paths_finds_family_in_later_path() {
+        let fonts = workspace_fonts_dir();
+        if !fonts.join("Libron-Regular.ttf").exists() {
+            return;
+        }
+        let empty = tempfile::tempdir().unwrap();
+        FontFamily::from_name_in_paths("Libron", &[empty.path(), fonts.as_path()]).unwrap();
+    }
+
+    #[test]
+    fn from_name_in_paths_errors_when_paths_empty() {
+        let result = FontFamily::from_name_in_paths("Libron", &[] as &[&Path]);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn from_name_delegates_to_from_name_in_paths() {
+        let fonts = workspace_fonts_dir();
+        if !fonts.join("Libron-Regular.ttf").exists() {
+            return;
+        }
+        FontFamily::from_name("Libron", &fonts).unwrap();
+    }
+}
diff --git a/crates/core/src/ota/cleanup.rs b/crates/core/src/ota/cleanup.rs
index 8029d4a2..1d2ff871 100644
--- a/crates/core/src/ota/cleanup.rs
+++ b/crates/core/src/ota/cleanup.rs
@@ -83,7 +83,7 @@ mod tests {
         std::fs::create_dir_all(install_dir.join("icons")).unwrap();
         std::fs::create_dir_all(install_dir.join("libs")).unwrap();
 
-        std::fs::write(install_dir.join("fonts/NotoSans-Regular.ttf"), b"owned").unwrap();
+        std::fs::write(install_dir.join("fonts/Libron-Regular.ttf"), b"owned").unwrap();
         std::fs::write(install_dir.join("fonts/custom.ttf"), b"user").unwrap();
         std::fs::write(install_dir.join("icons/home.svg"), b"owned").unwrap();
         std::fs::write(install_dir.join("libs/libfoo.so.1"), b"owned").unwrap();
@@ -91,7 +91,7 @@ mod tests {
 
         clean_bundled_files(&install_dir).unwrap();
 
-        assert!(!install_dir.join("fonts/NotoSans-Regular.ttf").exists());
+        assert!(!install_dir.join("fonts/Libron-Regular.ttf").exists());
         assert!(install_dir.join("fonts/custom.ttf").exists());
         assert!(!install_dir.join("icons/home.svg").exists());
         assert!(!install_dir.join("libs/libfoo.so.1").exists());
diff --git a/crates/core/src/settings/mod.rs b/crates/core/src/settings/mod.rs
index bb566bf3..79d71fcc 100644
--- a/crates/core/src/settings/mod.rs
+++ b/crates/core/src/settings/mod.rs
@@ -120,7 +120,7 @@ pub const DEFAULT_MARGIN_WIDTH: i32 = 8;
 // Default line height in ems.
 pub const DEFAULT_LINE_HEIGHT: f32 = 1.2;
 // Default font family name.
-pub const DEFAULT_FONT_FAMILY: &str = "Libertinus Serif";
+pub const DEFAULT_FONT_FAMILY: &str = "Libron";
 // Default text alignment.
 pub const DEFAULT_TEXT_ALIGN: TextAlign = TextAlign::Left;
 pub const HYPHEN_PENALTY: i32 = 50;
diff --git a/crates/core/src/view/reader/mod.rs b/crates/core/src/view/reader/mod.rs
index bd26cea6..57e9e23d 100644
--- a/crates/core/src/view/reader/mod.rs
+++ b/crates/core/src/view/reader/mod.rs
@@ -2708,6 +2708,9 @@ impl Reader {
             let mut families = family_names(&context.settings.reader.font_path)
                 .map_err(|e| error!("Can't get family names: {:#}.", e))
                 .unwrap_or_default();
+            if let Ok(install_families) = family_names(context.device.install_path("fonts")) {
+                families.extend(install_families);
+            }
             let current_family = self
                 .info
                 .reader
@@ -3364,13 +3367,7 @@ impl Reader {
 
         {
             let mut doc = self.doc.lock().unwrap();
-            let font_path = if font_family == DEFAULT_FONT_FAMILY {
-                "fonts"
-            } else {
-                &context.settings.reader.font_path
-            };
-
-            doc.set_font_family(font_family, font_path);
+            doc.set_font_family(font_family, &context.settings.reader.font_path);
 
             if self.synthetic {
                 let current_page = self.current_page.min(doc.pages_count() - 1);
diff --git a/devenv.nix b/devenv.nix
index 649503f4..96ef0f0c 100644
--- a/devenv.nix
+++ b/devenv.nix
@@ -402,8 +402,7 @@ in
   dotenv.enable = true;
 
   env = {
-    # override this in devenv.local.nix to the right place for your test cadmus root dir
-    # TEST_ROOT_DIR = "$DEVENV_ROOT" ;
+    TEST_ROOT_DIR = config.devenv.root;
 
     RUST_LOG = "cadmus_core=trace,cadmus=trace";
     RUST_BACKTRACE = "1";
diff --git a/docs/po/messages.pot b/docs/po/messages.pot
index d860a803..e6ec4448 100644
--- a/docs/po/messages.pot
+++ b/docs/po/messages.pot
@@ -1,7 +1,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: Cadmus Documentation\n"
-"POT-Creation-Date: 2026-07-09T12:27:48+02:00\n"
+"POT-Creation-Date: 2026-07-14T20:06:37+02:00\n"
 "MIME-Version: 1.0\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 "Content-Transfer-Encoding: 8bit\n"
@@ -24,7 +24,7 @@ msgstr ""
 msgid "Test builds"
 msgstr ""
 
-#: src/SUMMARY.md:7 src/installation/ota.md:1
+#: src/SUMMARY.md:7 src/installation/ota.md:1 src/fonts.md:108
 msgid "OTA updates"
 msgstr ""
 
@@ -44,133 +44,137 @@ msgstr ""
 msgid "Uninstalling Cadmus"
 msgstr ""
 
-#: src/SUMMARY.md:12 src/SUMMARY.md:17 src/settings/index.md:1
+#: src/SUMMARY.md:12 src/SUMMARY.md:18 src/settings/index.md:1 src/fonts.md:102
 #: src/ui/settings/index.md:1
 msgid "Settings"
 msgstr ""
 
-#: src/SUMMARY.md:13 src/ui/index.md:1
+#: src/SUMMARY.md:13 src/fonts.md:1
+msgid "Fonts"
+msgstr ""
+
+#: src/SUMMARY.md:14 src/ui/index.md:1
 msgid "User Interface"
 msgstr ""
 
-#: src/SUMMARY.md:14 src/ui/filechooser.md:1
+#: src/SUMMARY.md:15 src/ui/filechooser.md:1
 msgid "File Chooser"
 msgstr ""
 
-#: src/SUMMARY.md:15 src/ui/keyboard.md:1
+#: src/SUMMARY.md:16 src/ui/keyboard.md:1
 msgid "Keyboard"
 msgstr ""
 
-#: src/SUMMARY.md:16 src/ui/dictionary.md:1
+#: src/SUMMARY.md:17 src/ui/dictionary.md:1
 msgid "Dictionary"
 msgstr ""
 
-#: src/SUMMARY.md:18 src/installation/migration.md:112
+#: src/SUMMARY.md:19 src/installation/migration.md:112
 #: src/ui/settings/dictionaries.md:1
 msgid "Dictionaries"
 msgstr ""
 
-#: src/SUMMARY.md:19 src/library/index.md:1
+#: src/SUMMARY.md:20 src/library/index.md:1
 msgid "Library"
 msgstr ""
 
-#: src/SUMMARY.md:20
+#: src/SUMMARY.md:21
 msgid "Importing"
 msgstr ""
 
-#: src/SUMMARY.md:21 src/time-sync.md:1
+#: src/SUMMARY.md:22 src/time-sync.md:1
 msgid "Automatic Time Syncing"
 msgstr ""
 
-#: src/SUMMARY.md:22 src/auto-frontlight.md:1
+#: src/SUMMARY.md:23 src/auto-frontlight.md:1
 msgid "Automatic Frontlight"
 msgstr ""
 
-#: src/SUMMARY.md:23 src/database-backup.md:1
+#: src/SUMMARY.md:24 src/database-backup.md:1
 msgid "Database Backup"
 msgstr ""
 
-#: src/SUMMARY.md:24 src/installation/ota.md:86 src/troubleshooting/index.md:1
+#: src/SUMMARY.md:25 src/installation/ota.md:86 src/troubleshooting/index.md:1
 msgid "Troubleshooting"
 msgstr ""
 
-#: src/SUMMARY.md:25
+#: src/SUMMARY.md:26
 msgid "CHANGELOG"
 msgstr ""
 
-#: src/SUMMARY.md:29
+#: src/SUMMARY.md:30
 msgid "Contributor Guide"
 msgstr ""
 
-#: src/SUMMARY.md:31
+#: src/SUMMARY.md:32
 msgid "Development Environment"
 msgstr ""
 
-#: src/SUMMARY.md:32
+#: src/SUMMARY.md:33
 msgid "SSH"
 msgstr ""
 
-#: src/SUMMARY.md:33
+#: src/SUMMARY.md:34
 msgid "Code Style and Linting"
 msgstr ""
 
-#: src/SUMMARY.md:34
+#: src/SUMMARY.md:35
 msgid "Event System"
 msgstr ""
 
-#: src/SUMMARY.md:35 src/settings/index.md:723
+#: src/SUMMARY.md:36 src/settings/index.md:778
 msgid "Telemetry"
 msgstr ""
 
-#: src/SUMMARY.md:36
+#: src/SUMMARY.md:37
 msgid "Logging"
 msgstr ""
 
-#: src/SUMMARY.md:37
+#: src/SUMMARY.md:38
 msgid "Tracing"
 msgstr ""
 
-#: src/SUMMARY.md:38
+#: src/SUMMARY.md:39
 msgid "Profiling"
 msgstr ""
 
-#: src/SUMMARY.md:39
+#: src/SUMMARY.md:40
 msgid "Website"
 msgstr ""
 
-#: src/SUMMARY.md:40
+#: src/SUMMARY.md:41
 msgid "User guide"
 msgstr ""
 
-#: src/SUMMARY.md:41
+#: src/SUMMARY.md:42
 msgid "Translations"
 msgstr ""
 
-#: src/SUMMARY.md:42
+#: src/SUMMARY.md:43
 msgid "For developers"
 msgstr ""
 
-#: src/SUMMARY.md:43
+#: src/SUMMARY.md:44
 msgid "SQLite & SQLx"
 msgstr ""
 
-#: src/SUMMARY.md:44
+#: src/SUMMARY.md:45
 msgid "Library Database"
 msgstr ""
 
-#: src/SUMMARY.md:45
+#: src/SUMMARY.md:46
 msgid "Runtime Migrations"
 msgstr ""
 
-#: src/SUMMARY.md:49
+#: src/SUMMARY.md:50
 msgid "Investigations"
 msgstr ""
 
-#: src/SUMMARY.md:51
+#: src/SUMMARY.md:52
 msgid "Intro"
 msgstr ""
 
-#: src/SUMMARY.md:52
+#: src/SUMMARY.md:53
 msgid "DHCP IP Address Changes on WiFi Toggle"
 msgstr ""
 
@@ -1071,18 +1075,18 @@ msgstr ""
 
 #: src/settings/index.md:299 src/settings/index.md:315
 #: src/settings/index.md:329 src/settings/index.md:348
-#: src/settings/index.md:362 src/settings/index.md:382
-#: src/settings/index.md:398 src/settings/index.md:428
-#: src/settings/index.md:444 src/settings/index.md:460
-#: src/settings/index.md:476 src/settings/index.md:492
-#: src/settings/index.md:514 src/settings/index.md:535
-#: src/settings/index.md:550 src/settings/index.md:567
-#: src/settings/index.md:573 src/settings/index.md:579
-#: src/settings/index.md:587 src/settings/index.md:612
-#: src/settings/index.md:629 src/settings/index.md:641
-#: src/settings/index.md:649 src/settings/index.md:666
-#: src/settings/index.md:694 src/settings/index.md:751
-#: src/settings/index.md:766
+#: src/settings/index.md:363 src/settings/index.md:385
+#: src/settings/index.md:401 src/settings/index.md:433
+#: src/settings/index.md:449 src/settings/index.md:465
+#: src/settings/index.md:481 src/settings/index.md:497
+#: src/settings/index.md:519 src/settings/index.md:540
+#: src/settings/index.md:602 src/settings/index.md:619
+#: src/settings/index.md:625 src/settings/index.md:631
+#: src/settings/index.md:639 src/settings/index.md:664
+#: src/settings/index.md:681 src/settings/index.md:694
+#: src/settings/index.md:702 src/settings/index.md:721
+#: src/settings/index.md:749 src/settings/index.md:806
+#: src/settings/index.md:821
 msgid "✏️"
 msgstr ""
 
@@ -1128,359 +1132,393 @@ msgid ""
 "will also set the correct timezone. Uses time.cloudflare.com and ipapi.co."
 msgstr ""
 
-#: src/settings/index.md:360
+#: src/settings/index.md:361
 msgid "`auto-frontlight`"
 msgstr ""
 
-#: src/settings/index.md:364
+#: src/settings/index.md:365
 msgid ""
 "Automatically adjust the frontlight warmth and brightness based on the sun's "
 "position at the device's location."
 msgstr ""
 
-#: src/settings/index.md:366
+#: src/settings/index.md:367
 msgid "During the day warmth is at its minimum."
 msgstr ""
 
-#: src/settings/index.md:367
+#: src/settings/index.md:368
 msgid "Around sunrise and sunset warmth ramps gradually between zero and full."
 msgstr ""
 
-#: src/settings/index.md:368
+#: src/settings/index.md:369
 msgid ""
 "After sunset brightness is reduced to `auto-frontlight-night-brightness` and "
 "warmth stays at its maximum until sunrise."
 msgstr ""
 
-#: src/settings/index.md:370
+#: src/settings/index.md:372
 msgid ""
 "Coordinates are auto-detected during each time sync (via ipapi.co) and "
 "stored in `auto-frontlight-last-coordinates`. Set "
 "`auto-frontlight-manual-coordinates` to override the detected location."
 msgstr ""
 
-#: src/settings/index.md:380
+#: src/settings/index.md:383
 msgid "`auto-frontlight-night-brightness`"
 msgstr ""
 
-#: src/settings/index.md:384
+#: src/settings/index.md:387
 msgid ""
 "Frontlight brightness level (0.0–100.0) applied when the sun is below the "
 "horizon."
 msgstr ""
 
-#: src/settings/index.md:386
+#: src/settings/index.md:389
 msgid "This setting is optional. When not set, a default of `1.0` is used."
 msgstr ""
 
-#: src/settings/index.md:396
+#: src/settings/index.md:399
 msgid "`auto-frontlight-manual-coordinates`"
 msgstr ""
 
-#: src/settings/index.md:400
+#: src/settings/index.md:403
 msgid ""
 "GPS coordinates `[latitude, longitude]` to use for sun-position calculations "
 "instead of the auto-detected location. Takes priority over "
 "`auto-frontlight-last-coordinates`."
 msgstr ""
 
-#: src/settings/index.md:402
+#: src/settings/index.md:406
 msgid "This setting is optional."
 msgstr ""
 
-#: src/settings/index.md:412
+#: src/settings/index.md:416
 msgid "`auto-frontlight-last-coordinates`"
 msgstr ""
 
-#: src/settings/index.md:414
+#: src/settings/index.md:418
 msgid ""
 "GPS coordinates `[latitude, longitude]` last detected during a time sync. "
 "Written automatically — do not edit this by hand; set "
 "`auto-frontlight-manual-coordinates` to override the location instead."
 msgstr ""
 
-#: src/settings/index.md:416
+#: src/settings/index.md:421
 msgid "This setting is optional and managed automatically."
 msgstr ""
 
-#: src/settings/index.md:426
+#: src/settings/index.md:431
 msgid "`auto-suspend`"
 msgstr ""
 
-#: src/settings/index.md:430
+#: src/settings/index.md:435
 msgid ""
 "Number of minutes of inactivity after which the device will automatically go "
 "to sleep."
 msgstr ""
 
-#: src/settings/index.md:432 src/settings/index.md:448
+#: src/settings/index.md:437 src/settings/index.md:453
 msgid "Zero means never."
 msgstr ""
 
-#: src/settings/index.md:442
+#: src/settings/index.md:447
 msgid "`auto-power-off`"
 msgstr ""
 
-#: src/settings/index.md:446
+#: src/settings/index.md:451
 msgid "Delay in days after which a suspended device will power off."
 msgstr ""
 
-#: src/settings/index.md:458
+#: src/settings/index.md:463
 msgid "`button-scheme`"
 msgstr ""
 
-#: src/settings/index.md:462
+#: src/settings/index.md:467
 msgid ""
 "Defines how the back and forward buttons are mapped to page forward and page "
 "backward actions."
 msgstr ""
 
-#: src/settings/index.md:464
+#: src/settings/index.md:469
 msgid "Possible values: `\"natural\"`, `\"inverted\"`."
 msgstr ""
 
-#: src/settings/index.md:474
+#: src/settings/index.md:479
 msgid "`locale`"
 msgstr ""
 
-#: src/settings/index.md:478
+#: src/settings/index.md:483
 msgid ""
 "The preferred language for the user interface, using BCP 47 format (e.g., "
 "`\"en-US\"`, `\"de-DE\"`)."
 msgstr ""
 
-#: src/settings/index.md:480
+#: src/settings/index.md:485
 msgid "This setting is optional. When not set, `en-GB` is used."
 msgstr ""
 
-#: src/settings/index.md:490
+#: src/settings/index.md:495
 msgid "`startup-mode`"
 msgstr ""
 
-#: src/settings/index.md:494
+#: src/settings/index.md:499
 msgid "What to show when Cadmus starts."
 msgstr ""
 
-#: src/settings/index.md:496
+#: src/settings/index.md:501
 msgid "`\"home\"` — open the home screen (default)."
 msgstr ""
 
-#: src/settings/index.md:497
+#: src/settings/index.md:502
 msgid ""
 "`\"last-file\"` — re-open the last book you were reading. If there is no "
 "unfinished book in the selected library, the home screen is shown instead."
 msgstr ""
 
-#: src/settings/index.md:508
+#: src/settings/index.md:513
 msgid "Reader"
 msgstr ""
 
-#: src/settings/index.md:510
+#: src/settings/index.md:515
 msgid "Settings that control the reading experience."
 msgstr ""
 
-#: src/settings/index.md:512
+#: src/settings/index.md:517
 msgid "`reader.finished`"
 msgstr ""
 
-#: src/settings/index.md:516
+#: src/settings/index.md:521
 msgid "What to do when you finish reading a book."
 msgstr ""
 
-#: src/settings/index.md:518 src/settings/index.md:592
+#: src/settings/index.md:523 src/settings/index.md:644
 msgid "Possible values:"
 msgstr ""
 
-#: src/settings/index.md:520
+#: src/settings/index.md:525
 msgid "`\"notify\"` (show a notification)"
 msgstr ""
 
-#: src/settings/index.md:521
+#: src/settings/index.md:526
 msgid "`\"close\"` (close the book and go back)"
 msgstr ""
 
-#: src/settings/index.md:522
+#: src/settings/index.md:527
 msgid "`\"go-to-next\"` (open the next book in the library)."
 msgstr ""
 
-#: src/settings/index.md:533
+#: src/settings/index.md:538
 msgid "`reader.dithered-kinds`"
 msgstr ""
 
-#: src/settings/index.md:537
+#: src/settings/index.md:542
 msgid "File extensions rendered with dithering by default."
 msgstr ""
 
-#: src/settings/index.md:548
+#: src/settings/index.md:553
+msgid "`reader.font-path`"
+msgstr ""
+
+#: src/settings/index.md:555
+msgid ""
+"The directory Cadmus scans for additional reading fonts. Bundled Cadmus "
+"fonts are always available regardless of this setting. See "
+"[Fonts](../fonts.md) for details on installing custom fonts."
+msgstr ""
+
+#: src/settings/index.md:568
+msgid "`reader.font-family`"
+msgstr ""
+
+#: src/settings/index.md:570
+msgid ""
+"The default reading font family name. New installs default to `Libron`. "
+"Existing configurations using `Libertinus Serif` continue to work because "
+"Libertinus remains bundled."
+msgstr ""
+
+#: src/settings/index.md:583
+msgid "`reader.font-size`"
+msgstr ""
+
+#: src/settings/index.md:585
+msgid "The default font size in points."
+msgstr ""
+
+#: src/settings/index.md:598
+msgid "See [Fonts](../fonts.md) for more info."
+msgstr ""
+
+#: src/settings/index.md:600
 msgid "Libraries"
 msgstr ""
 
-#: src/settings/index.md:552
+#: src/settings/index.md:604
 msgid "Document library configuration. Each library has a name, path, and mode."
 msgstr ""
 
-#: src/settings/index.md:565
+#: src/settings/index.md:617
 msgid "`libraries.name`"
 msgstr ""
 
-#: src/settings/index.md:569
+#: src/settings/index.md:621
 msgid "Display name for the library."
 msgstr ""
 
-#: src/settings/index.md:571
+#: src/settings/index.md:623
 msgid "`libraries.path`"
 msgstr ""
 
-#: src/settings/index.md:575
+#: src/settings/index.md:627
 msgid "Directory path containing documents."
 msgstr ""
 
-#: src/settings/index.md:577
+#: src/settings/index.md:629
 msgid "`libraries.mode`"
 msgstr ""
 
-#: src/settings/index.md:581
+#: src/settings/index.md:633
 msgid "Library indexing mode."
 msgstr ""
 
-#: src/settings/index.md:583
+#: src/settings/index.md:635
 msgid "Possible values: `\"database\"`, `\"filesystem\"`."
 msgstr ""
 
-#: src/settings/index.md:585
+#: src/settings/index.md:637
 msgid "`libraries.finished`"
 msgstr ""
 
-#: src/settings/index.md:589
+#: src/settings/index.md:641
 msgid ""
 "Override the `reader.finished` setting for this specific library. When set, "
 "this takes precedence over the global reader setting."
 msgstr ""
 
-#: src/settings/index.md:594
+#: src/settings/index.md:646
 msgid "`\"notify\"`"
 msgstr ""
 
-#: src/settings/index.md:595
+#: src/settings/index.md:647
 msgid "`\"close\"`"
 msgstr ""
 
-#: src/settings/index.md:596
+#: src/settings/index.md:648
 msgid "`\"go-to-next\"`."
 msgstr ""
 
-#: src/settings/index.md:597
+#: src/settings/index.md:649
 msgid "Leave unset to inherit the global `reader.finished` setting."
 msgstr ""
 
-#: src/settings/index.md:610
+#: src/settings/index.md:662
 msgid "Intermissions"
 msgstr ""
 
-#: src/settings/index.md:614
+#: src/settings/index.md:666
 msgid "Defines the images displayed when entering an intermission state."
 msgstr ""
 
-#: src/settings/index.md:627
+#: src/settings/index.md:679
 msgid "`intermissions.suspend`"
 msgstr ""
 
-#: src/settings/index.md:631
+#: src/settings/index.md:683
 msgid "Image displayed when the device enters sleep mode."
 msgstr ""
 
-#: src/settings/index.md:633
+#: src/settings/index.md:685
 msgid ""
 "Setting this to `\"calendar:\"` also enables the calendar refresh: every 5 "
 "minutes, the device wakes, shows the calendar, and then goes back to sleep "
 "automatically."
 msgstr ""
 
-#: src/settings/index.md:637
+#: src/settings/index.md:689
 msgid ""
 "Possible values: `\"logo:\"` (built-in logo), `\"cover:\"` (current book "
 "cover), `\"calendar:\"` (built-in calendar), or a path to a custom image "
 "file."
 msgstr ""
 
-#: src/settings/index.md:639
+#: src/settings/index.md:692
 msgid "`intermissions.power-off`"
 msgstr ""
 
-#: src/settings/index.md:643
+#: src/settings/index.md:696
 msgid "Image displayed when the device powers off."
 msgstr ""
 
-#: src/settings/index.md:645 src/settings/index.md:653
+#: src/settings/index.md:698 src/settings/index.md:706
 msgid ""
 "Possible values: `\"logo:\"` (built-in logo), `\"cover:\"` (current book "
 "cover), or a path to a custom image file."
 msgstr ""
 
-#: src/settings/index.md:647
+#: src/settings/index.md:700
 msgid "`intermissions.share`"
 msgstr ""
 
-#: src/settings/index.md:651
+#: src/settings/index.md:704
 msgid "Image displayed when entering USB sharing mode."
 msgstr ""
 
-#: src/settings/index.md:655
+#: src/settings/index.md:708
 msgid "Import"
 msgstr ""
 
-#: src/settings/index.md:657
+#: src/settings/index.md:710
 msgid ""
 "These settings control how Cadmus imports documents from your device. They "
 "are available in the **Settings → Import** menu."
 msgstr ""
 
-#: src/settings/index.md:660
+#: src/settings/index.md:713
 msgid ""
 "Import scanning happens automatically on startup using incremental file "
 "checking — files are only re-scanned if their modification time or size has "
 "changed since the last import."
 msgstr ""
 
-#: src/settings/index.md:662
+#: src/settings/index.md:716
 msgid ""
 "To trigger a full re-scan of all files regardless of cached values, use the "
 "**Force Full Import** action button in the Import settings category."
 msgstr ""
 
-#: src/settings/index.md:664
+#: src/settings/index.md:719
 msgid "`import.sync-metadata`"
 msgstr ""
 
-#: src/settings/index.md:668
+#: src/settings/index.md:723
 msgid "Re-extract metadata (title, author, etc.) whenever a document changes."
 msgstr ""
 
-#: src/settings/index.md:679
+#: src/settings/index.md:734
 msgid "`import.metadata-kinds`"
 msgstr ""
 
-#: src/settings/index.md:681
+#: src/settings/index.md:736
 msgid "File extensions of documents whose metadata is extracted during import."
 msgstr ""
 
-#: src/settings/index.md:692
+#: src/settings/index.md:747
 msgid "`import.allowed-kinds`"
 msgstr ""
 
-#: src/settings/index.md:696
+#: src/settings/index.md:751
 msgid "File extensions of documents considered during the import process."
 msgstr ""
 
-#: src/settings/index.md:707
+#: src/settings/index.md:762
 msgid "OTA"
 msgstr ""
 
-#: src/settings/index.md:709
+#: src/settings/index.md:764
 msgid "The OTA feature downloads builds from GitHub."
 msgstr ""
 
-#: src/settings/index.md:711
+#: src/settings/index.md:766
 msgid ""
 "Authentication for main branch and PR builds uses **GitHub device auth "
 "flow**. When you select a build that requires authentication, Cadmus will "
@@ -1489,191 +1527,492 @@ msgid ""
 "once you authorize."
 msgstr ""
 
-#: src/settings/index.md:717
+#: src/settings/index.md:772
 msgid ""
 "The token is saved to disk after the first authorization so you will not be "
 "prompted again on subsequent downloads."
 msgstr ""
 
-#: src/settings/index.md:720
+#: src/settings/index.md:775
 msgid ""
 "For step-by-step instructions with screenshots, see the [OTA "
 "updates](../installation/ota.md) guide."
 msgstr ""
 
-#: src/settings/index.md:725
+#: src/settings/index.md:780
 msgid ""
 "Cadmus writes JSON logs to disk. When the build enables the `tracing` "
 "feature, it can also export logs to an OpenTelemetry endpoint."
 msgstr ""
 
-#: src/settings/index.md:728
+#: src/settings/index.md:783
 msgid "These settings are available in the **Settings → Telemetry** menu."
 msgstr ""
 
-#: src/settings/index.md:731
+#: src/settings/index.md:786
 msgid ""
 "Changes to these settings only take effect after restarting Cadmus. The "
 "application initializes telemetry on startup."
 msgstr ""
 
-#: src/settings/index.md:734
+#: src/settings/index.md:789
 msgid "`logging`"
 msgstr ""
 
-#: src/settings/index.md:749
+#: src/settings/index.md:804
 msgid "`logging.enabled`"
 msgstr ""
 
-#: src/settings/index.md:753
+#: src/settings/index.md:808
 msgid "Enable or disable structured JSON logging."
 msgstr ""
 
-#: src/settings/index.md:764
+#: src/settings/index.md:819
 msgid "`logging.level`"
 msgstr ""
 
-#: src/settings/index.md:768
+#: src/settings/index.md:823
 msgid "Minimum log level to record."
 msgstr ""
 
-#: src/settings/index.md:770
+#: src/settings/index.md:825
 msgid ""
 "Possible values: `\"trace\"`, `\"debug\"`, `\"info\"`, `\"warn\"`, "
 "`\"error\"`."
 msgstr ""
 
-#: src/settings/index.md:781
+#: src/settings/index.md:836
 msgid "`logging.max-files`"
 msgstr ""
 
-#: src/settings/index.md:783
+#: src/settings/index.md:838
 msgid ""
 "Number of log files to keep. Only the most recent N files are kept — older "
 "ones are deleted automatically when Cadmus starts."
 msgstr ""
 
-#: src/settings/index.md:786 src/settings/index.md:879
+#: src/settings/index.md:841 src/settings/index.md:936
 msgid "Default: `3`"
 msgstr ""
 
-#: src/settings/index.md:787
+#: src/settings/index.md:842
 msgid "Set to `0` to keep all log files."
 msgstr ""
 
-#: src/settings/index.md:798
+#: src/settings/index.md:853
 msgid "`logging.otlp-endpoint`"
 msgstr ""
 
-#: src/settings/index.md:800
+#: src/settings/index.md:855
 msgid "✏️ (only when the `tracing` feature is enabled)"
 msgstr ""
 
-#: src/settings/index.md:802
+#: src/settings/index.md:857
 msgid "Optional OTLP endpoint for exporting logs to an OpenTelemetry collector."
 msgstr ""
 
-#: src/settings/index.md:813 src/settings/index.md:834
+#: src/settings/index.md:868 src/settings/index.md:889
 msgid "Environment override:"
 msgstr ""
 
-#: src/settings/index.md:815
+#: src/settings/index.md:870
 msgid ""
 "`OTEL_EXPORTER_OTLP_ENDPOINT` takes precedence over `logging.otlp-endpoint`."
 msgstr ""
 
-#: src/settings/index.md:817
+#: src/settings/index.md:872
 msgid "`logging.pyroscope-endpoint`"
 msgstr ""
 
-#: src/settings/index.md:819
+#: src/settings/index.md:874
 msgid "✏️ (only when the `profiling` feature is enabled)"
 msgstr ""
 
-#: src/settings/index.md:821
+#: src/settings/index.md:876
 msgid ""
 "Optional Pyroscope server URL for continuous profiling. When set, Cadmus "
 "starts both a heap profiling agent (via jemalloc) and a CPU profiling agent "
 "(via pprof) that push profiles to this endpoint."
 msgstr ""
 
-#: src/settings/index.md:836
+#: src/settings/index.md:891
 msgid ""
 "`PYROSCOPE_SERVER_URL` takes precedence over `logging.pyroscope-endpoint`."
 msgstr ""
 
-#: src/settings/index.md:838
+#: src/settings/index.md:893
 msgid "`logging.enable-kern-log`"
 msgstr ""
 
-#: src/settings/index.md:840 src/settings/index.md:856
+#: src/settings/index.md:895 src/settings/index.md:911
 msgid "🧪 📱 ✏️"
 msgstr ""
 
-#: src/settings/index.md:842
+#: src/settings/index.md:897
 msgid ""
 "Captures kernel logs via `logread -F` and forwards them to structured "
 "logging with the target `cadmus_core::logging:kern`."
 msgstr ""
 
-#: src/settings/index.md:854
+#: src/settings/index.md:909
 msgid "`logging.enable-dbus-log`"
 msgstr ""
 
-#: src/settings/index.md:858
+#: src/settings/index.md:913
 msgid ""
 "Captures D-Bus signals via the built-in zbus-based DbusMonitorTask and "
 "forwards them to structured logging."
 msgstr ""
 
-#: src/settings/index.md:870
+#: src/settings/index.md:925
 msgid "Settings Retention"
 msgstr ""
 
-#: src/settings/index.md:872
+#: src/settings/index.md:927
 msgid ""
 "Cadmus stores each version's settings in a separate file in the `Settings/` "
 "directory (for example, `Settings-v1.2.3.toml`). This ensures backward and "
 "forward compatibility when you upgrade."
 msgstr ""
 
-#: src/settings/index.md:875
+#: src/settings/index.md:931
 msgid "`settings-retention`"
 msgstr ""
 
-#: src/settings/index.md:877
+#: src/settings/index.md:933
 msgid ""
 "Number of recent version settings files to keep. Only the most recent N "
 "version files are kept. When a new version is saved, older versions beyond "
 "this limit are deleted automatically."
 msgstr ""
 
-#: src/settings/index.md:880
+#: src/settings/index.md:937
 msgid "Set to `0` to keep all version files"
 msgstr ""
 
-#: src/settings/index.md:890
+#: src/settings/index.md:947
 msgid "`db-backup-retention`"
 msgstr ""
 
-#: src/settings/index.md:892
+#: src/settings/index.md:949
 msgid ""
 "Number of database backups to keep. When a new backup is created and the "
 "total would exceed this limit, the oldest backups are deleted automatically."
 msgstr ""
 
-#: src/settings/index.md:895 src/database-backup.md:76
+#: src/settings/index.md:952 src/database-backup.md:76
 msgid "Default: `2`"
 msgstr ""
 
-#: src/settings/index.md:896 src/database-backup.md:77
+#: src/settings/index.md:953 src/database-backup.md:77
 msgid "Set to `0` to disable backups entirely."
 msgstr ""
 
-#: src/settings/index.md:898
+#: src/settings/index.md:955
 msgid "See [Database Backup](../database-backup.md) for more details."
 msgstr ""
 
+#: src/fonts.md:3
+msgid ""
+"Cadmus ships with reading fonts optimized for e-ink displays, plus "
+"additional fonts for the app interface and in-book HTML fallbacks. You can "
+"switch fonts while reading or install your own."
+msgstr ""
+
+#: src/fonts.md:7
+msgid "Pre-installed reading fonts"
+msgstr ""
+
+#: src/fonts.md:9
+msgid "Cadmus's reading fonts come from two open-source projects:"
+msgstr ""
+
+#: src/fonts.md:11
+msgid ""
+"[ebook-fonts](https://github.com/nicoverbruggen/ebook-fonts) by Nico "
+"Verbruggen — reading fonts tuned for e-ink displays. See the [interactive "
+"showcase](https://ebook-fonts.nicoverbruggen.be/) to preview them."
+msgstr ""
+
+#: src/fonts.md:14
+msgid ""
+"[Libertinus](https://github.com/alerque/libertinus) — classic serif, sans, "
+"and mono families, plus Nico's metric-tweaked **NV Libertinus** from the "
+"ebook-fonts extra collection."
+msgstr ""
+
+#: src/fonts.md:17
+msgid "ebook-fonts (Core Collection)"
+msgstr ""
+
+#: src/fonts.md:19 src/fonts.md:33 src/fonts.md:47
+msgid "Font"
+msgstr ""
+
+#: src/fonts.md:19 src/fonts.md:33
+msgid "Style"
+msgstr ""
+
+#: src/fonts.md:21
+msgid "Libron"
+msgstr ""
+
+#: src/fonts.md:21
+msgid "Serif (default)"
+msgstr ""
+
+#: src/fonts.md:22
+msgid "Sourcerer"
+msgstr ""
+
+#: src/fonts.md:22 src/fonts.md:23 src/fonts.md:24 src/fonts.md:25
+#: src/fonts.md:27 src/fonts.md:35 src/fonts.md:36
+msgid "Serif"
+msgstr ""
+
+#: src/fonts.md:23
+msgid "Cartisse"
+msgstr ""
+
+#: src/fonts.md:24
+msgid "NV Charis"
+msgstr ""
+
+#: src/fonts.md:25
+msgid "NV Garamond"
+msgstr ""
+
+#: src/fonts.md:26
+msgid "NV Bitter"
+msgstr ""
+
+#: src/fonts.md:26
+msgid "Slab serif"
+msgstr ""
+
+#: src/fonts.md:27
+msgid "NV Palatium"
+msgstr ""
+
+#: src/fonts.md:28
+msgid "NV Jost"
+msgstr ""
+
+#: src/fonts.md:28 src/fonts.md:37
+msgid "Sans"
+msgstr ""
+
+#: src/fonts.md:29
+msgid "NV Legible Next"
+msgstr ""
+
+#: src/fonts.md:29
+msgid "Sans (accessibility)"
+msgstr ""
+
+#: src/fonts.md:31
+msgid "Libertinus"
+msgstr ""
+
+#: src/fonts.md:35
+msgid "NV Libertinus"
+msgstr ""
+
+#: src/fonts.md:36
+msgid "Libertinus Serif"
+msgstr ""
+
+#: src/fonts.md:37
+msgid "Libertinus Sans"
+msgstr ""
+
+#: src/fonts.md:38
+msgid "Libertinus Mono"
+msgstr ""
+
+#: src/fonts.md:38
+msgid "Monospace"
+msgstr ""
+
+#: src/fonts.md:40
+msgid "Other packaged fonts"
+msgstr ""
+
+#: src/fonts.md:42
+msgid ""
+"Cadmus also ships fonts from "
+"[Noto](https://github.com/notofonts/noto-fonts), [Source Code "
+"Pro](https://github.com/adobe-fonts/source-code-pro), and [Google "
+"Fonts](https://github.com/googlefonts/google-fonts) for the app interface "
+"and HTML rendering fallbacks:"
+msgstr ""
+
+#: src/fonts.md:47
+msgid "Used for"
+msgstr ""
+
+#: src/fonts.md:49
+msgid "Noto Sans"
+msgstr ""
+
+#: src/fonts.md:49
+msgid "Menus, settings, and other app text"
+msgstr ""
+
+#: src/fonts.md:50
+msgid "Noto Serif"
+msgstr ""
+
+#: src/fonts.md:50
+msgid "Serif text in the app interface"
+msgstr ""
+
+#: src/fonts.md:51
+msgid "Source Code Pro"
+msgstr ""
+
+#: src/fonts.md:51
+msgid "Monospace in the app and code blocks in books"
+msgstr ""
+
+#: src/fonts.md:52
+msgid "Varela Round"
+msgstr ""
+
+#: src/fonts.md:52
+msgid "On-screen keyboard"
+msgstr ""
+
+#: src/fonts.md:53
+msgid "Cormorant"
+msgstr ""
+
+#: src/fonts.md:53
+msgid "Startup and intermission screens"
+msgstr ""
+
+#: src/fonts.md:54
+msgid "Parisienne"
+msgstr ""
+
+#: src/fonts.md:54
+msgid "Decorative cursive text in EPUB/HTML content"
+msgstr ""
+
+#: src/fonts.md:55
+msgid "Delius"
+msgstr ""
+
+#: src/fonts.md:55
+msgid "Decorative fantasy text in EPUB/HTML content"
+msgstr ""
+
+#: src/fonts.md:57
+msgid "Changing the font while reading"
+msgstr ""
+
+#: src/fonts.md:59
+msgid "Open a book in the reader."
+msgstr ""
+
+#: src/fonts.md:60
+msgid "Tap the **font family** button in the reader toolbar."
+msgstr ""
+
+#: src/fonts.md:61
+msgid "Select a font from the list."
+msgstr ""
+
+#: src/fonts.md:63
+msgid ""
+"The menu shows fonts from Cadmus's packaged collection and any fonts in your "
+"custom font directory (see below). When you select a font, Cadmus resolves "
+"the family name using the order described in [How Cadmus resolves "
+"fonts](#how-cadmus-resolves-fonts)."
+msgstr ""
+
+#: src/fonts.md:67
+msgid "How Cadmus resolves fonts"
+msgstr ""
+
+#: src/fonts.md:69
+msgid ""
+"When you pick a font in the reader or reopen a book with a saved "
+"[`font-family`](settings/index.md#readerfont-family), Cadmus looks for that "
+"family name in two places, **in this order**:"
+msgstr ""
+
+#: src/fonts.md:73
+msgid ""
+"**Packaged fonts** — shipped with Cadmus and updated via "
+"[OTA](installation/ota.md)"
+msgstr ""
+
+#: src/fonts.md:74
+msgid ""
+"**Your custom font directory** — "
+"[`reader.font-path`](settings/index.md#readerfont-path) (default "
+"`/mnt/onboard/fonts/`)"
+msgstr ""
+
+#: src/fonts.md:77
+msgid ""
+"If the same family name exists in both places, the **packaged** copy is used."
+msgstr ""
+
+#: src/fonts.md:79
+msgid ""
+"Your chosen family replaces Cadmus's default **serif** stack for reflowable "
+"books. Paragraphs the book styles as sans-serif, monospace, cursive, or "
+"fantasy keep those respective packaged fallbacks. If Cadmus cannot find the "
+"family name, the previous font is kept."
+msgstr ""
+
+#: src/fonts.md:84
+msgid "Installing additional fonts"
+msgstr ""
+
+#: src/fonts.md:86
+msgid ""
+"To add your own fonts, copy `.ttf` or `.otf` files into your custom font "
+"directory (by default at the root of your Kobo device):"
+msgstr ""
+
+#: src/fonts.md:97
+msgid "Cadmus scans that directory recursively, so fonts can live in subfolders."
+msgstr ""
+
+#: src/fonts.md:99
+msgid ""
+"Point Cadmus at your custom directory with "
+"[`reader.font-path`](settings/index.md#readerfont-path) if you use a "
+"different location."
+msgstr ""
+
+#: src/fonts.md:104
+msgid ""
+"Font options can also be set in your settings file. See the [Reader "
+"settings](settings/index.md#reader) section for `font-family`, `font-path`, "
+"`font-size`, and related entries."
+msgstr ""
+
+#: src/fonts.md:110
+msgid ""
+"[OTA updates](installation/ota.md) replace Cadmus-packaged fonts before "
+"installing the new release. Cadmus removes **each shipped font file "
+"individually** — it does not delete the whole `fonts/` directory — so any "
+"extra files you placed in Cadmus's install `fonts/` folder survive the "
+"update if they are not part of the release."
+msgstr ""
+
+#: src/fonts.md:116
+msgid ""
+"Under normal use, your custom fonts live in a **separate directory** "
+"([`reader.font-path`](settings/index.md#readerfont-path), default "
+"`/mnt/onboard/fonts/`) and are never touched by OTA. Packaged fonts stay in "
+"Cadmus's install directory."
+msgstr ""
+
 #: src/ui/index.md:3
 msgid ""
 "This section explains the different parts of Cadmus you interact with while "
diff --git a/docs/src/SUMMARY.md b/docs/src/SUMMARY.md
index 53625215..758a60a3 100644
--- a/docs/src/SUMMARY.md
+++ b/docs/src/SUMMARY.md
@@ -10,6 +10,7 @@
   - [Using with KFMon](installation/kfmon.md)
   - [Uninstalling Cadmus](installation/uninstall.md)
 - [Settings](settings/index.md)
+- [Fonts](fonts.md)
 - [User Interface](ui/index.md)
   - [File Chooser](ui/filechooser.md)
   - [Keyboard](ui/keyboard.md)
diff --git a/docs/src/contributing/devenv-setup.md b/docs/src/contributing/devenv-setup.md
index 20d867f8..dab70399 100644
--- a/docs/src/contributing/devenv-setup.md
+++ b/docs/src/contributing/devenv-setup.md
@@ -24,13 +24,14 @@ This guide covers setup on both Linux and macOS.
 
    ```bash
    cargo xtask download-assets
+   cargo xtask download-fonts
    ```
 
    > [!NOTE]
    > `cadmus-core` generates some compile-time metadata from the bundled asset
-   > directories. For Kobo builds, make sure `bin/`, `resources/`, and
-   > `hyphenation-patterns/` are present before `cargo xtask build-kobo` so the
-   > generated asset list is complete.
+   > directories. For Kobo builds, make sure `bin/`, `resources/`,
+   > `hyphenation-patterns/`, and `fonts/` are present before
+   > `cargo xtask build-kobo` so the generated asset list is complete.
    >
    > Thirdparty C/C++ dependencies (MuPDF, libwebp, zlib, etc.) are tracked as git
    > submodules and built automatically by `build.rs` when you run `cargo build` or
@@ -49,6 +50,7 @@ Once inside the devenv shell, these commands are available:
 | Command                       | Description                                                 |
 | ----------------------------- | ----------------------------------------------------------- |
 | `cargo xtask download-assets` | Download packaged Plato runtime assets                      |
+| `cargo xtask download-fonts`  | Download bundled font files into `fonts/`                   |
 | `cargo xtask test`            | Run the test suite across the feature matrix                |
 | `cargo xtask run-emulator`    | Run the emulator                                            |
 | `cargo xtask build-kobo`      | Cross-compile for Kobo device                               |
@@ -95,7 +97,7 @@ The `docs:build` task uses `execIfModified` to only rebuild when documentation f
 
 ## Kobo Build Notes
 
-- `cargo xtask download-assets` must run before `cargo xtask build-kobo`.
+- `cargo xtask download-assets` and `cargo xtask download-fonts` must run before `cargo xtask build-kobo`.
 - OTA updates delete Cadmus-owned bundled files before reboot, then Kobo
   extracts the new `KoboRoot.tgz` over the install directory.
 - User files outside the generated Cadmus-owned asset list must be preserved.
diff --git a/docs/src/fonts.md b/docs/src/fonts.md
new file mode 100644
index 00000000..ec252705
--- /dev/null
+++ b/docs/src/fonts.md
@@ -0,0 +1,119 @@
+# Fonts
+
+Cadmus ships with reading fonts optimized for e-ink displays, plus
+additional fonts for the app interface and in-book HTML fallbacks. You can switch
+fonts while reading or install your own.
+
+## Pre-installed reading fonts
+
+Cadmus's reading fonts come from two open-source projects:
+
+- [ebook-fonts](https://github.com/nicoverbruggen/ebook-fonts) by Nico Verbruggen —
+  reading fonts tuned for e-ink displays. See the [interactive showcase](https://ebook-fonts.nicoverbruggen.be/)
+  to preview them.
+- [Libertinus](https://github.com/alerque/libertinus) — classic serif, sans, and mono families,
+  plus Nico's metric-tweaked **NV Libertinus** from the ebook-fonts extra collection.
+
+### ebook-fonts (Core Collection)
+
+| Font            | Style                |
+| --------------- | -------------------- |
+| Libron          | Serif (default)      |
+| Sourcerer       | Serif                |
+| Cartisse        | Serif                |
+| NV Charis       | Serif                |
+| NV Garamond     | Serif                |
+| NV Bitter       | Slab serif           |
+| NV Palatium     | Serif                |
+| NV Jost         | Sans                 |
+| NV Legible Next | Sans (accessibility) |
+
+### Libertinus
+
+| Font             | Style     |
+| ---------------- | --------- |
+| NV Libertinus    | Serif     |
+| Libertinus Serif | Serif     |
+| Libertinus Sans  | Sans      |
+| Libertinus Mono  | Monospace |
+
+## Other packaged fonts
+
+Cadmus also ships fonts from [Noto](https://github.com/notofonts/noto-fonts),
+[Source Code Pro](https://github.com/adobe-fonts/source-code-pro), and
+[Google Fonts](https://github.com/googlefonts/google-fonts) for the app interface
+and HTML rendering fallbacks:
+
+| Font            | Used for                                      |
+| --------------- | --------------------------------------------- |
+| Noto Sans       | Menus, settings, and other app text           |
+| Noto Serif      | Serif text in the app interface               |
+| Source Code Pro | Monospace in the app and code blocks in books |
+| Varela Round    | On-screen keyboard                            |
+| Cormorant       | Startup and intermission screens              |
+| Parisienne      | Decorative cursive text in EPUB/HTML content  |
+| Delius          | Decorative fantasy text in EPUB/HTML content  |
+
+## Changing the font while reading
+
+1. Open a book in the reader.
+2. Tap the **font family** button in the reader toolbar.
+3. Select a font from the list.
+
+The menu shows fonts from Cadmus's packaged collection and any fonts in your
+custom font directory (see below). When you select a font, Cadmus resolves the
+family name using the order described in [How Cadmus resolves fonts](#how-cadmus-resolves-fonts).
+
+## How Cadmus resolves fonts
+
+When you pick a font in the reader or reopen a book with a saved
+[`font-family`](settings/index.md#readerfont-family), Cadmus looks for that family
+name in two places, **in this order**:
+
+1. **Packaged fonts** — shipped with Cadmus and updated via [OTA](installation/ota.md)
+2. **Your custom font directory** — [`reader.font-path`](settings/index.md#readerfont-path)
+   (default `/mnt/onboard/fonts/`)
+
+If the same family name exists in both places, the **packaged** copy is used.
+
+Your chosen family replaces Cadmus's default **serif** stack for reflowable
+books. Paragraphs the book styles as sans-serif, monospace, cursive, or fantasy
+keep those respective packaged fallbacks. If Cadmus cannot find the family name,
+the previous font is kept.
+
+## Installing additional fonts
+
+To add your own fonts, copy `.ttf` or `.otf` files into your custom font
+directory (by default at the root of your Kobo device):
+
+<!-- i18n:skip-start -->
+
+```text
+/mnt/onboard/fonts/
+```
+
+<!-- i18n:skip-end -->
+
+Cadmus scans that directory recursively, so fonts can live in subfolders.
+
+Point Cadmus at your custom directory with [`reader.font-path`](settings/index.md#readerfont-path)
+if you use a different location.
+
+## Settings
+
+Font options can also be set in your settings file. See the
+[Reader settings](settings/index.md#reader) section for `font-family`,
+`font-path`, `font-size`, and related entries.
+
+## OTA updates
+
+[OTA updates](installation/ota.md) replace Cadmus-packaged fonts before
+installing the new release. Cadmus removes **each shipped font file
+individually** — it does not delete the whole `fonts/` directory — so any
+extra files you placed in Cadmus's install `fonts/` folder survive the update
+if they are not part of the release.
+
+Under normal use, your custom fonts live in a **separate directory**
+([`reader.font-path`](settings/index.md#readerfont-path), default
+`/mnt/onboard/fonts/`) and are never touched by OTA. Packaged fonts stay in
+Cadmus's install directory.
diff --git a/docs/src/settings/index.md b/docs/src/settings/index.md
index 92dcbd45..ba480798 100644
--- a/docs/src/settings/index.md
+++ b/docs/src/settings/index.md
@@ -18,7 +18,7 @@ Settings can be changed via **Main Menu → Settings**, which opens the built-in
 <!-- i18n:skip-start -->
 
 ```toml
-{{#include ../../../contrib/Settings-sample.toml}}
+{{ #include ../../../contrib/Settings-sample.toml}}
 ```
 
 <!-- i18n:skip-end -->
@@ -80,7 +80,8 @@ auto-share = false
 
 ✏️
 
-Automatically synchronize the device time via NTP when WiFi connects. This will also set the correct timezone. Uses time.cloudflare.com and ipapi.co.
+Automatically synchronize the device time via NTP when WiFi connects. This will also set the correct timezone. Uses
+time.cloudflare.com and ipapi.co.
 
 <!-- i18n:skip-start -->
 
@@ -98,9 +99,11 @@ Automatically adjust the frontlight warmth and brightness based on the sun's pos
 
 - During the day warmth is at its minimum.
 - Around sunrise and sunset warmth ramps gradually between zero and full.
-- After sunset brightness is reduced to `auto-frontlight-night-brightness` and warmth stays at its maximum until sunrise.
+- After sunset brightness is reduced to `auto-frontlight-night-brightness` and warmth stays at its maximum until
+  sunrise.
 
-Coordinates are auto-detected during each time sync (via ipapi.co) and stored in `auto-frontlight-last-coordinates`. Set `auto-frontlight-manual-coordinates` to override the detected location.
+Coordinates are auto-detected during each time sync (via ipapi.co) and stored in `auto-frontlight-last-coordinates`. Set
+`auto-frontlight-manual-coordinates` to override the detected location.
 
 <!-- i18n:skip-start -->
 
@@ -130,7 +133,8 @@ auto-frontlight-night-brightness = 10.0
 
 ✏️
 
-GPS coordinates `[latitude, longitude]` to use for sun-position calculations instead of the auto-detected location. Takes priority over `auto-frontlight-last-coordinates`.
+GPS coordinates `[latitude, longitude]` to use for sun-position calculations instead of the auto-detected location.
+Takes priority over `auto-frontlight-last-coordinates`.
 
 This setting is optional.
 
@@ -144,7 +148,8 @@ auto-frontlight-manual-coordinates = [51.5074, -0.1278]
 
 ### `auto-frontlight-last-coordinates`
 
-GPS coordinates `[latitude, longitude]` last detected during a time sync. Written automatically — do not edit this by hand; set `auto-frontlight-manual-coordinates` to override the location instead.
+GPS coordinates `[latitude, longitude]` last detected during a time sync. Written automatically — do not edit this by
+hand; set `auto-frontlight-manual-coordinates` to override the location instead.
 
 This setting is optional and managed automatically.
 
@@ -278,6 +283,53 @@ dithered-kinds = ["cbz", "png", "jpg", "jpeg", "webp"]
 
 <!-- i18n:skip-end -->
 
+### `reader.font-path`
+
+The directory Cadmus scans for additional reading fonts. Bundled Cadmus fonts
+are always available regardless of this setting. See [Fonts](../fonts.md) for
+details on installing custom fonts.
+
+<!-- i18n:skip-start -->
+
+```toml
+[reader]
+font-path = "/mnt/onboard/fonts"
+```
+
+<!-- i18n:skip-end -->
+
+### `reader.font-family`
+
+The default reading font family name. New installs default to `Libron`.
+Existing configurations using `Libertinus Serif` continue to work because
+Libertinus remains bundled.
+
+<!-- i18n:skip-start -->
+
+```toml
+[reader]
+font-family = "Libron"
+```
+
+<!-- i18n:skip-end -->
+
+### `reader.font-size`
+
+The default font size in points.
+
+<!-- i18n:skip-start -->
+
+```toml
+[reader]
+font-size = 11.0
+min-font-size = 5.5
+max-font-size = 16.5
+```
+
+<!-- i18n:skip-end -->
+
+See [Fonts](../fonts.md) for more info.
+
 ## Libraries
 
 ✏️
@@ -367,7 +419,8 @@ Setting this to `"calendar:"` also enables the calendar refresh: every 5
 minutes, the device wakes, shows the calendar, and then goes back to sleep
 automatically.
 
-- Possible values: `"logo:"` (built-in logo), `"cover:"` (current book cover), `"calendar:"` (built-in calendar), or a path to a custom image file.
+- Possible values: `"logo:"` (built-in logo), `"cover:"` (current book cover), `"calendar:"` (built-in calendar), or a
+  path to a custom image file.
 
 ### `intermissions.power-off`
 
@@ -390,9 +443,11 @@ Image displayed when entering USB sharing mode.
 These settings control how Cadmus imports documents from your device.
 They are available in the **Settings → Import** menu.
 
-Import scanning happens automatically on startup using incremental file checking — files are only re-scanned if their modification time or size has changed since the last import.
+Import scanning happens automatically on startup using incremental file checking — files are only re-scanned if their
+modification time or size has changed since the last import.
 
-To trigger a full re-scan of all files regardless of cached values, use the **Force Full Import** action button in the Import settings category.
+To trigger a full re-scan of all files regardless of cached values, use the **Force Full Import** action button in the
+Import settings category.
 
 ### `import.sync-metadata`
 
@@ -602,12 +657,14 @@ enable-dbus-log = false
 
 ## Settings Retention
 
-Cadmus stores each version's settings in a separate file in the `Settings/` directory (for example, `Settings-v1.2.3.toml`).
+Cadmus stores each version's settings in a separate file in the `Settings/` directory (for example,
+`Settings-v1.2.3.toml`).
 This ensures backward and forward compatibility when you upgrade.
 
 ### `settings-retention`
 
-Number of recent version settings files to keep. Only the most recent N version files are kept. When a new version is saved, older versions beyond this limit are deleted automatically.
+Number of recent version settings files to keep. Only the most recent N version files are kept. When a new version is
+saved, older versions beyond this limit are deleted automatically.
 
 - Default: `3`
 - Set to `0` to keep all version files
diff --git a/fonts/Cormorant-Regular.ttf b/fonts/Cormorant-Regular.ttf
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diff --git a/fonts/LibertinusSerif-Bold.otf b/fonts/LibertinusSerif-Bold.otf
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diff --git a/fonts/VarelaRound-Regular.ttf b/fonts/VarelaRound-Regular.ttf
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Binary files a/fonts/VarelaRound-Regular.ttf and /dev/null differ
diff --git a/renovate.json b/renovate.json
index 5f2db716..37b9e06b 100644
--- a/renovate.json
+++ b/renovate.json
@@ -65,6 +65,19 @@
       "groupName": "mupdf",
       "groupSlug": "mupdf",
       "addLabels": ["thirdparty"]
+    },
+    {
+      "description": "Group bundled font release pins and font git submodules",
+      "matchManagers": ["custom.regex", "git-submodules"],
+      "matchPackageNames": [
+        "nicoverbruggen/ebook-fonts",
+        "alerque/libertinus",
+        "adobe-fonts/source-code-pro",
+        "thirdparty/noto-fonts",
+        "thirdparty/google-fonts"
+      ],
+      "groupName": "bundled fonts",
+      "groupSlug": "bundled-fonts"
     }
   ],
   "customManagers": [
@@ -186,6 +199,42 @@
       "depNameTemplate": "baskerville/plato",
       "versioningTemplate": "semver"
     },
+    {
+      "customType": "regex",
+      "managerFilePatterns": [
+        "/^xtask\\/src\\/tasks\\/download_fonts\\/.*\\.rs$/"
+      ],
+      "matchStrings": [
+        "EBOOK_FONTS_VERSION: &str = \\\"(?<currentValue>[^\\\"]+)\\\""
+      ],
+      "datasourceTemplate": "github-releases",
+      "depNameTemplate": "nicoverbruggen/ebook-fonts",
+      "versioningTemplate": "semver-coerced"
+    },
+    {
+      "customType": "regex",
+      "managerFilePatterns": [
+        "/^xtask\\/src\\/tasks\\/download_fonts\\/.*\\.rs$/"
+      ],
+      "matchStrings": [
+        "LIBERTINUS_VERSION: &str = \\\"(?<currentValue>[^\\\"]+)\\\""
+      ],
+      "datasourceTemplate": "github-releases",
+      "depNameTemplate": "alerque/libertinus",
+      "versioningTemplate": "semver-coerced"
+    },
+    {
+      "customType": "regex",
+      "managerFilePatterns": [
+        "/^xtask\\/src\\/tasks\\/download_fonts\\/.*\\.rs$/"
+      ],
+      "matchStrings": [
+        "SOURCE_CODE_RELEASE: &str = \\\"(?<currentValue>[^\\\"]+)\\\""
+      ],
+      "datasourceTemplate": "github-releases",
+      "depNameTemplate": "adobe-fonts/source-code-pro",
+      "versioningTemplate": "semver-coerced"
+    },
     {
       "customType": "regex",
       "managerFilePatterns": ["/^crates\\/build-deps\\/src\\/versions\\.rs$/"],
diff --git a/thirdparty/google-fonts b/thirdparty/google-fonts
new file mode 160000
index 00000000..ec0464b9
--- /dev/null
+++ b/thirdparty/google-fonts
@@ -0,0 +1 @@
+Subproject commit ec0464b978de222073645d6d3366f3fdf03376d8
diff --git a/thirdparty/noto-fonts b/thirdparty/noto-fonts
new file mode 160000
index 00000000..20bc5918
--- /dev/null
+++ b/thirdparty/noto-fonts
@@ -0,0 +1 @@
+Subproject commit 20bc5918912503bc1537a407a694738c33c048aa
diff --git a/xtask/src/lib.rs b/xtask/src/lib.rs
index 66132c6f..209aea49 100644
--- a/xtask/src/lib.rs
+++ b/xtask/src/lib.rs
@@ -26,6 +26,7 @@
 //! | [`install-importer`](tasks::install_importer) | Install the Cadmus importer crate |
 //! | [`docs`](tasks::docs) | Build the full documentation website |
 //! | [`download-assets`](tasks::download_assets) | Download static asset dirs from the latest release |
+//! | [`download-fonts`](tasks::download_fonts) | Download bundled font files into `fonts/` |
 //! | [`dist`](tasks::dist) | Assemble the Kobo distribution directory |
 //! | [`bundle`](tasks::bundle) | Package a `KoboRoot.tgz` ready for device installation |
 //! | [`setup`](tasks::setup) | Build thirdparty deps (SQLite) needed before `cargo build` |
@@ -81,6 +82,8 @@ pub enum Command {
     Docs(DocsArgs),
     /// Download static asset directories from the latest GitHub release.
     DownloadAssets,
+    /// Download bundled font files into the workspace `fonts/` directory.
+    DownloadFonts,
     /// Assemble the Kobo distribution directory from build outputs.
     Dist(DistArgs),
     /// Package a KoboRoot.tgz ready for device installation.
@@ -108,6 +111,7 @@ pub fn run() -> Result<()> {
         Command::InstallImporter(args) => tasks::install_importer::run(args),
         Command::Docs(args) => tasks::docs::run(args),
         Command::DownloadAssets => tasks::download_assets::run(),
+        Command::DownloadFonts => tasks::download_fonts::run(),
         Command::Dist(args) => tasks::dist::run(args),
         Command::Bundle(args) => tasks::bundle::run(args),
         Command::Setup(args) => tasks::setup::run(args),
diff --git a/xtask/src/tasks/dist.rs b/xtask/src/tasks/dist.rs
index 0ddb9136..7fc8b7a5 100644
--- a/xtask/src/tasks/dist.rs
+++ b/xtask/src/tasks/dist.rs
@@ -126,9 +126,14 @@ fn copy_assets(root: &Path, dist_dir: &Path) -> Result<()> {
     for dir in dirs {
         let src = root.join(dir);
         if !src.exists() {
+            let hint = if dir == "fonts" {
+                "Run `cargo xtask download-fonts` to download it."
+            } else {
+                "Run `cargo xtask download-assets` to download it."
+            };
             bail!(
                 "Required asset directory '{}' not found.\n\
-                 Run `cargo xtask download-assets` to download it.",
+                 {hint}",
                 src.display()
             );
         }
diff --git a/xtask/src/tasks/download_fonts/font/ebook.rs b/xtask/src/tasks/download_fonts/font/ebook.rs
new file mode 100644
index 00000000..9c66b03f
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/ebook.rs
@@ -0,0 +1,213 @@
+use std::path::Path;
+
+use anyhow::{Context, Result};
+use build_deps::markers;
+
+use crate::tasks::download_fonts::util;
+use crate::tasks::util::{fs, github};
+
+const REPO: &str = "nicoverbruggen/ebook-fonts";
+/// Tracked by Renovate via a regex manager in `renovate.json`.
+pub const EBOOK_FONTS_VERSION: &str = "v2026.07.02";
+const CORE_ASSET: &str = "other-core-fonts.zip";
+const EXTRA_ASSET: &str = "other-extra-fonts.zip";
+
+const CORE_FILES: &[&str] = &[
+    "Cartisse-Bold.ttf",
+    "Cartisse-BoldItalic.ttf",
+    "Cartisse-Italic.ttf",
+    "Cartisse-Regular.ttf",
+    "Libron-Bold.ttf",
+    "Libron-BoldItalic.ttf",
+    "Libron-Italic.ttf",
+    "Libron-Regular.ttf",
+    "NV_Bitter-Bold.ttf",
+    "NV_Bitter-BoldItalic.ttf",
+    "NV_Bitter-Italic.ttf",
+    "NV_Bitter-Regular.ttf",
+    "NV_Charis-Bold.ttf",
+    "NV_Charis-BoldItalic.ttf",
+    "NV_Charis-Italic.ttf",
+    "NV_Charis-Regular.ttf",
+    "NV_Garamond-Bold.ttf",
+    "NV_Garamond-BoldItalic.ttf",
+    "NV_Garamond-Italic.ttf",
+    "NV_Garamond-Regular.ttf",
+    "NV_Jost-Bold.ttf",
+    "NV_Jost-BoldItalic.ttf",
+    "NV_Jost-Italic.ttf",
+    "NV_Jost-Regular.ttf",
+    "NV_Legible_Next-Bold.ttf",
+    "NV_Legible_Next-BoldItalic.ttf",
+    "NV_Legible_Next-Italic.ttf",
+    "NV_Legible_Next-Regular.ttf",
+    "NV_Palatium-Bold.ttf",
+    "NV_Palatium-BoldItalic.ttf",
+    "NV_Palatium-Italic.ttf",
+    "NV_Palatium-Regular.ttf",
+    "Sourcerer-Bold.ttf",
+    "Sourcerer-BoldItalic.ttf",
+    "Sourcerer-Italic.ttf",
+    "Sourcerer-Regular.ttf",
+];
+
+const EXTRA_FILES: &[&str] = &[
+    "NV_Libertinus-Bold.ttf",
+    "NV_Libertinus-BoldItalic.ttf",
+    "NV_Libertinus-Italic.ttf",
+    "NV_Libertinus-Regular.ttf",
+];
+
+pub fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    if is_complete(fonts_dir) {
+        return Ok(());
+    }
+
+    if !markers::is_version_current(fonts_dir, EBOOK_FONTS_VERSION) {
+        remove_managed_files(fonts_dir)?;
+    }
+
+    let cache_dir = root.join(format!(".cache/ebook-fonts/{EBOOK_FONTS_VERSION}"));
+
+    let core_archive = download_release_asset(&cache_dir, CORE_ASSET)?;
+    util::extract_cached_archive(
+        &core_archive,
+        || download_release_asset(&cache_dir, CORE_ASSET).map(|_| ()),
+        |archive| {
+            fs::extract_zip_matching_flat(archive, fonts_dir, "", ".ttf")
+                .context("failed to extract core fonts from ebook-fonts archive")
+        },
+    )?;
+
+    let extra_archive = download_release_asset(&cache_dir, EXTRA_ASSET)?;
+    util::extract_cached_archive(
+        &extra_archive,
+        || download_release_asset(&cache_dir, EXTRA_ASSET).map(|_| ()),
+        |archive| {
+            fs::extract_zip_matching_flat(archive, fonts_dir, "NV_Libertinus", ".ttf")
+                .context("failed to extract extra fonts from ebook-fonts extra archive")
+        },
+    )?;
+
+    markers::mark_version(fonts_dir, "ebook-fonts", EBOOK_FONTS_VERSION)?;
+    Ok(())
+}
+
+pub fn is_complete(fonts_dir: &Path) -> bool {
+    managed_files().all(|name| fonts_dir.join(name).exists())
+        && markers::is_version_current(fonts_dir, EBOOK_FONTS_VERSION)
+}
+
+fn managed_files() -> impl Iterator<Item = &'static str> {
+    CORE_FILES.iter().chain(EXTRA_FILES.iter()).copied()
+}
+
+fn remove_managed_files(fonts_dir: &Path) -> Result<()> {
+    for name in managed_files() {
+        let path = fonts_dir.join(name);
+        if path.exists() {
+            std::fs::remove_file(&path)
+                .with_context(|| format!("failed to remove stale font file {name}"))?;
+        }
+    }
+    Ok(())
+}
+
+fn download_release_asset(cache_dir: &Path, asset: &str) -> Result<std::path::PathBuf> {
+    util::ensure_cached_release_asset(cache_dir, asset, || {
+        println!("Fetching {asset} from {REPO} {EBOOK_FONTS_VERSION}…");
+        github::fetch_release_asset(REPO, EBOOK_FONTS_VERSION, asset)
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use std::fs;
+    use std::path::Path;
+
+    use super::*;
+
+    fn write_test_zip(path: &Path, entries: &[(&str, &[u8])]) {
+        let file = fs::File::create(path).unwrap();
+        let mut writer = zip::ZipWriter::new(file);
+        let options = zip::write::SimpleFileOptions::default()
+            .compression_method(zip::CompressionMethod::Stored);
+
+        for (name, contents) in entries {
+            writer.start_file(*name, options).unwrap();
+            std::io::Write::write_all(&mut writer, contents).unwrap();
+        }
+
+        writer.finish().unwrap();
+    }
+
+    fn touch_managed_files(fonts_dir: &Path, contents: &[u8]) {
+        for name in managed_files() {
+            fs::write(fonts_dir.join(name), contents).unwrap();
+        }
+    }
+
+    fn seed_ebook_cache(root: &Path, libron_contents: &[u8]) {
+        let cache_dir = root.join(format!(".cache/ebook-fonts/{EBOOK_FONTS_VERSION}"));
+        fs::create_dir_all(&cache_dir).unwrap();
+
+        let core_entries: Vec<(&str, &[u8])> = CORE_FILES
+            .iter()
+            .map(|name| {
+                let content = if *name == "Libron-Regular.ttf" {
+                    libron_contents
+                } else {
+                    b"core".as_slice()
+                };
+                (*name, content)
+            })
+            .collect();
+        write_test_zip(&cache_dir.join(CORE_ASSET), &core_entries);
+
+        let extra_entries: Vec<(&str, &[u8])> = EXTRA_FILES
+            .iter()
+            .map(|name| (*name, b"extra".as_slice()))
+            .collect();
+        write_test_zip(&cache_dir.join(EXTRA_ASSET), &extra_entries);
+    }
+
+    #[test]
+    fn is_complete_false_when_version_stale() {
+        let fonts_dir = tempfile::tempdir().unwrap();
+        touch_managed_files(fonts_dir.path(), b"font");
+        markers::mark_version(fonts_dir.path(), "ebook-fonts", "v2020.01.01").unwrap();
+
+        assert!(!is_complete(fonts_dir.path()));
+    }
+
+    #[test]
+    fn is_complete_true_when_up_to_date() {
+        let fonts_dir = tempfile::tempdir().unwrap();
+        touch_managed_files(fonts_dir.path(), b"font");
+        markers::mark_version(fonts_dir.path(), "ebook-fonts", EBOOK_FONTS_VERSION).unwrap();
+
+        assert!(is_complete(fonts_dir.path()));
+    }
+
+    #[test]
+    fn install_refreshes_on_stale_version() {
+        let root = tempfile::tempdir().unwrap();
+        let fonts_dir = tempfile::tempdir().unwrap();
+        seed_ebook_cache(root.path(), b"fresh");
+
+        fs::write(fonts_dir.path().join("Libron-Regular.ttf"), b"stale").unwrap();
+        markers::mark_version(fonts_dir.path(), "ebook-fonts", "v2020.01.01").unwrap();
+
+        install(root.path(), fonts_dir.path()).unwrap();
+
+        assert_eq!(
+            fs::read(fonts_dir.path().join("Libron-Regular.ttf")).unwrap(),
+            b"fresh"
+        );
+        assert!(markers::is_version_current(
+            fonts_dir.path(),
+            EBOOK_FONTS_VERSION
+        ));
+        assert!(is_complete(fonts_dir.path()));
+    }
+}
diff --git a/xtask/src/tasks/download_fonts/font/google.rs b/xtask/src/tasks/download_fonts/font/google.rs
new file mode 100644
index 00000000..9690fa0c
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/google.rs
@@ -0,0 +1,29 @@
+use std::path::Path;
+
+use anyhow::Result;
+
+use super::super::util;
+
+const SUBMODULE: &str = "thirdparty/google-fonts";
+const MARKER_NAME: &str = "google-fonts";
+
+const FILES: &[(&str, &str)] = &[
+    (
+        "VarelaRound-Regular.ttf",
+        "ofl/varelaround/VarelaRound-Regular.ttf",
+    ),
+    ("Cormorant-Regular.ttf", "ofl/cormorant/Cormorant[wght].ttf"),
+    (
+        "Parisienne-Regular.ttf",
+        "ofl/parisienne/Parisienne-Regular.ttf",
+    ),
+    ("Delius-Regular.ttf", "ofl/delius/Delius-Regular.ttf"),
+];
+
+pub(crate) fn is_complete(root: &Path, fonts_dir: &Path) -> bool {
+    util::is_submodule_install_current(root, fonts_dir, SUBMODULE, MARKER_NAME, FILES)
+}
+
+pub(crate) fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    util::install_from_submodule(root, SUBMODULE, fonts_dir, MARKER_NAME, FILES)
+}
diff --git a/xtask/src/tasks/download_fonts/font/libertinus.rs b/xtask/src/tasks/download_fonts/font/libertinus.rs
new file mode 100644
index 00000000..bd72dc5b
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/libertinus.rs
@@ -0,0 +1,66 @@
+use std::path::Path;
+
+use anyhow::{Context, Result};
+
+use crate::tasks::download_fonts::util;
+use crate::tasks::util::{fs, github};
+
+const REPO: &str = "alerque/libertinus";
+/// Tracked by Renovate via a regex manager in `renovate.json`.
+///
+/// GitHub release tags use a `v` prefix; archive names and in-zip paths omit it
+/// (e.g. tag `v7.051` → asset `Libertinus-7.051.zip`).
+pub const LIBERTINUS_VERSION: &str = "v7.051";
+
+const FILES: &[&str] = &[
+    "LibertinusSerif-Regular.otf",
+    "LibertinusSerif-Italic.otf",
+    "LibertinusSerif-Bold.otf",
+    "LibertinusSerif-BoldItalic.otf",
+    "LibertinusSans-Regular.otf",
+    "LibertinusSans-Italic.otf",
+    "LibertinusSans-Bold.otf",
+    "LibertinusMono-Regular.otf",
+];
+
+pub fn is_complete(fonts_dir: &Path) -> bool {
+    FILES.iter().all(|name| fonts_dir.join(name).exists())
+}
+
+pub fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    if is_complete(fonts_dir) {
+        return Ok(());
+    }
+
+    let cache_dir = root.join(format!(".cache/libertinus/{LIBERTINUS_VERSION}"));
+    let archive_version = LIBERTINUS_VERSION
+        .strip_prefix('v')
+        .unwrap_or(LIBERTINUS_VERSION);
+    let asset_name = format!("Libertinus-{archive_version}.zip");
+
+    let archive = util::ensure_cached_release_asset(&cache_dir, &asset_name, || {
+        println!("Fetching {asset_name} from {REPO} {LIBERTINUS_VERSION}…");
+        github::fetch_release_asset(REPO, LIBERTINUS_VERSION, &asset_name)
+    })?;
+
+    let otf_prefix = format!("Libertinus-{archive_version}/static/OTF/");
+    let entries: Vec<(String, String)> = FILES
+        .iter()
+        .map(|name| (format!("{otf_prefix}{name}"), (*name).to_string()))
+        .collect();
+
+    util::extract_cached_archive(
+        &archive,
+        || {
+            util::ensure_cached_release_asset(&cache_dir, &asset_name, || {
+                println!("Re-fetching {asset_name} from {REPO} {LIBERTINUS_VERSION}…");
+                github::fetch_release_asset(REPO, LIBERTINUS_VERSION, &asset_name)
+            })
+            .map(|_| ())
+        },
+        |archive| {
+            fs::extract_zip_entries_flat(archive, fonts_dir, &entries)
+                .context("failed to extract Libertinus fonts")
+        },
+    )
+}
diff --git a/xtask/src/tasks/download_fonts/font/mod.rs b/xtask/src/tasks/download_fonts/font/mod.rs
new file mode 100644
index 00000000..05d7ebc9
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/mod.rs
@@ -0,0 +1,46 @@
+//! Bundled font sources for [`super::run`].
+//!
+//! Each submodule corresponds to one upstream (ebook-fonts, Libertinus, Noto,
+//! Source Code, Google Fonts) and exposes its own [`install`](ebook::install)
+//! and [`is_complete`](ebook::is_complete).  [`install`] and [`is_complete`]
+//! at this level orchestrate every source.
+
+use std::path::Path;
+
+use anyhow::{Context, Result};
+
+use build_deps::ensure_submodules;
+
+pub mod ebook;
+pub mod google;
+pub mod libertinus;
+pub mod noto;
+pub mod source_code;
+
+/// Installs every bundled font source into `fonts_dir`.
+///
+/// Downloads are cached under `root/.cache/`.  Submodule-backed sources rely on
+/// [`ensure_submodules`] from `build-deps`.  Existing destination files are left
+/// untouched.
+///
+/// # Errors
+///
+/// Returns an error if any source fails to download or extract.
+pub fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    ensure_submodules(root).context("failed to initialise git submodules")?;
+    ebook::install(root, fonts_dir)?;
+    libertinus::install(root, fonts_dir)?;
+    noto::install(root, fonts_dir)?;
+    source_code::install(root, fonts_dir)?;
+    google::install(root, fonts_dir)?;
+    Ok(())
+}
+
+/// Returns `true` when every bundled font source is already present in `fonts_dir`.
+pub fn is_complete(root: &Path, fonts_dir: &Path) -> bool {
+    ebook::is_complete(fonts_dir)
+        && libertinus::is_complete(fonts_dir)
+        && noto::is_complete(root, fonts_dir)
+        && source_code::is_complete(fonts_dir)
+        && google::is_complete(root, fonts_dir)
+}
diff --git a/xtask/src/tasks/download_fonts/font/noto.rs b/xtask/src/tasks/download_fonts/font/noto.rs
new file mode 100644
index 00000000..ffb64433
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/noto.rs
@@ -0,0 +1,48 @@
+use std::path::Path;
+
+use anyhow::Result;
+
+use super::super::util;
+
+const SUBMODULE: &str = "thirdparty/noto-fonts";
+const MARKER_NAME: &str = "noto-fonts";
+
+const FILES: &[(&str, &str)] = &[
+    (
+        "NotoSans-Regular.ttf",
+        "hinted/ttf/NotoSans/NotoSans-Regular.ttf",
+    ),
+    (
+        "NotoSans-Italic.ttf",
+        "hinted/ttf/NotoSans/NotoSans-Italic.ttf",
+    ),
+    ("NotoSans-Bold.ttf", "hinted/ttf/NotoSans/NotoSans-Bold.ttf"),
+    (
+        "NotoSans-BoldItalic.ttf",
+        "hinted/ttf/NotoSans/NotoSans-BoldItalic.ttf",
+    ),
+    (
+        "NotoSerif-Regular.ttf",
+        "hinted/ttf/NotoSerif/NotoSerif-Regular.ttf",
+    ),
+    (
+        "NotoSerif-Italic.ttf",
+        "hinted/ttf/NotoSerif/NotoSerif-Italic.ttf",
+    ),
+    (
+        "NotoSerif-Bold.ttf",
+        "hinted/ttf/NotoSerif/NotoSerif-Bold.ttf",
+    ),
+    (
+        "NotoSerif-BoldItalic.ttf",
+        "hinted/ttf/NotoSerif/NotoSerif-BoldItalic.ttf",
+    ),
+];
+
+pub(crate) fn is_complete(root: &Path, fonts_dir: &Path) -> bool {
+    util::is_submodule_install_current(root, fonts_dir, SUBMODULE, MARKER_NAME, FILES)
+}
+
+pub(crate) fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    util::install_from_submodule(root, SUBMODULE, fonts_dir, MARKER_NAME, FILES)
+}
diff --git a/xtask/src/tasks/download_fonts/font/source_code.rs b/xtask/src/tasks/download_fonts/font/source_code.rs
new file mode 100644
index 00000000..ba0abba0
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/font/source_code.rs
@@ -0,0 +1,60 @@
+use std::path::Path;
+
+use anyhow::{Context, Result};
+
+use crate::tasks::download_fonts::util;
+use crate::tasks::util::{fs, github};
+
+const REPO: &str = "adobe-fonts/source-code-pro";
+/// Tracked by Renovate via a regex manager in `renovate.json`.
+pub const SOURCE_CODE_RELEASE: &str = "2.042R-u/1.062R-i/1.026R-vf";
+/// Asset name bundled in [`SOURCE_CODE_RELEASE`]; update manually when the
+/// upstream release layout changes.
+const VF_ASSET: &str = "VF-source-code-VF-1.026R.zip";
+
+const FILES: &[&str] = &[
+    "SourceCodeVariable-Roman.otf",
+    "SourceCodeVariable-Italic.otf",
+];
+
+const ZIP_ENTRIES: &[(&str, &str)] = &[
+    (
+        "VF/SourceCodeVF-Upright.otf",
+        "SourceCodeVariable-Roman.otf",
+    ),
+    (
+        "VF/SourceCodeVF-Italic.otf",
+        "SourceCodeVariable-Italic.otf",
+    ),
+];
+
+pub fn is_complete(fonts_dir: &Path) -> bool {
+    FILES.iter().all(|name| fonts_dir.join(name).exists())
+}
+
+pub fn install(root: &Path, fonts_dir: &Path) -> Result<()> {
+    if is_complete(fonts_dir) {
+        return Ok(());
+    }
+
+    let cache_dir = root.join(format!(".cache/source-code-pro/{SOURCE_CODE_RELEASE}"));
+    let archive = util::ensure_cached_release_asset(&cache_dir, VF_ASSET, || {
+        println!("Fetching {VF_ASSET} from {REPO} {SOURCE_CODE_RELEASE}…");
+        github::fetch_release_asset(REPO, SOURCE_CODE_RELEASE, VF_ASSET)
+    })?;
+
+    util::extract_cached_archive(
+        &archive,
+        || {
+            util::ensure_cached_release_asset(&cache_dir, VF_ASSET, || {
+                println!("Re-fetching {VF_ASSET} from {REPO} {SOURCE_CODE_RELEASE}…");
+                github::fetch_release_asset(REPO, SOURCE_CODE_RELEASE, VF_ASSET)
+            })
+            .map(|_| ())
+        },
+        |archive| {
+            fs::extract_zip_entries_flat(archive, fonts_dir, ZIP_ENTRIES)
+                .context("failed to extract Source Code VF fonts")
+        },
+    )
+}
diff --git a/xtask/src/tasks/download_fonts/mod.rs b/xtask/src/tasks/download_fonts/mod.rs
new file mode 100644
index 00000000..8ee494db
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/mod.rs
@@ -0,0 +1,59 @@
+//! `cargo xtask download-fonts` — download bundled font files for Cadmus.
+//!
+//! Assembles the `fonts/` directory from reader sources and pinned UI
+//! upstreams. Each source lives under [`font`] and exposes an `install`
+//! function.
+//!
+//! ## Caching
+//!
+//! Release archives are cached locally under `.cache/` during download.
+//! CI restores the assembled `fonts/` directory via the `cache-fonts` action.
+//! Noto and Google UI fonts are copied from git submodules under `thirdparty/`.
+
+mod font;
+mod util;
+
+use std::path::Path;
+
+use anyhow::{Context, Result, bail};
+
+use crate::tasks::util::workspace;
+
+pub use font::ebook::EBOOK_FONTS_VERSION;
+pub use font::libertinus::LIBERTINUS_VERSION;
+pub use font::source_code::SOURCE_CODE_RELEASE;
+
+/// Downloads and assembles the workspace `fonts/` directory.
+///
+/// Skips network I/O when every expected file is already present.
+///
+/// # Errors
+///
+/// Returns an error if any download or extraction step fails.
+pub fn run() -> Result<()> {
+    let root = workspace::root()?;
+    let fonts_dir = root.join("fonts");
+
+    if all_fonts_present(&root, &fonts_dir) {
+        println!("All font files already present in fonts/, skipping download.");
+        return Ok(());
+    }
+
+    std::fs::create_dir_all(&fonts_dir).context("failed to create fonts/ directory")?;
+
+    font::install(&root, &fonts_dir)?;
+
+    if !all_fonts_present(&root, &fonts_dir) {
+        bail!("fonts/ is still incomplete after download-fonts");
+    }
+
+    let file_count = std::fs::read_dir(&fonts_dir)
+        .map(|entries| entries.filter_map(Result::ok).count())
+        .unwrap_or(0);
+    println!("fonts/ is ready ({file_count} files).");
+    Ok(())
+}
+
+fn all_fonts_present(root: &Path, fonts_dir: &Path) -> bool {
+    fonts_dir.exists() && font::is_complete(root, fonts_dir)
+}
diff --git a/xtask/src/tasks/download_fonts/util.rs b/xtask/src/tasks/download_fonts/util.rs
new file mode 100644
index 00000000..4db3200c
--- /dev/null
+++ b/xtask/src/tasks/download_fonts/util.rs
@@ -0,0 +1,417 @@
+//! Shared helpers for font sources.
+//!
+//! Font submodules under [`super::font`] copy files from `thirdparty/` via
+//! [`install_from_submodule`].  Release archives are extracted with helpers in
+//! [`crate::tasks::util::fs`].
+
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context, Result};
+use build_deps::markers;
+
+use crate::tasks::util::github::{self, Asset};
+
+fn submodule_marker_dir(fonts_dir: &Path, name: &str) -> PathBuf {
+    fonts_dir.join(format!(".markers/{name}"))
+}
+
+/// Returns `true` when `files` are present and the submodule gitlink matches
+/// the recorded marker under `fonts_dir/.markers/{name}/`.
+pub(crate) fn is_submodule_install_current(
+    root: &Path,
+    fonts_dir: &Path,
+    submodule: &str,
+    name: &str,
+    files: &[(&str, &str)],
+) -> bool {
+    let marker_dir = submodule_marker_dir(fonts_dir, name);
+    files.iter().all(|(dest, _)| fonts_dir.join(dest).exists())
+        && markers::is_built(root, &marker_dir, submodule)
+}
+
+/// Copies `files` from a submodule into `fonts_dir`.
+///
+/// Each entry is `(dest_filename, path_relative_to_submodule_root)`. When the
+/// submodule gitlink changes, managed destination files are removed and
+/// recopied.
+///
+/// Call [`build_deps::ensure_submodules`] before invoking this function.
+///
+/// # Errors
+///
+/// Returns an error if the submodule is missing a source file or a copy fails.
+pub(crate) fn install_from_submodule(
+    root: &Path,
+    submodule: &str,
+    fonts_dir: &Path,
+    name: &str,
+    files: &[(&str, &str)],
+) -> Result<()> {
+    let marker_dir = submodule_marker_dir(fonts_dir, name);
+    if is_submodule_install_current(root, fonts_dir, submodule, name, files) {
+        return Ok(());
+    }
+
+    if !markers::is_built(root, &marker_dir, submodule) {
+        for (dest_name, _) in files {
+            let dest = fonts_dir.join(dest_name);
+            if dest.exists() {
+                std::fs::remove_file(&dest)
+                    .with_context(|| format!("failed to remove stale font file {dest_name}"))?;
+            }
+        }
+    }
+
+    let submodule_root = root.join(submodule);
+    if !submodule_root.is_dir() {
+        anyhow::bail!(
+            "{submodule} not found — run `git submodule update --init --recursive` first"
+        );
+    }
+
+    for &(dest_name, rel_path) in files {
+        let dest = fonts_dir.join(dest_name);
+        let src = submodule_root.join(rel_path);
+        if !src.is_file() {
+            anyhow::bail!(
+                "missing font file {} in submodule {submodule}",
+                src.display()
+            );
+        }
+        println!("Copying {dest_name} from {submodule}/{rel_path}…");
+        std::fs::copy(&src, &dest)
+            .with_context(|| format!("failed to copy {dest_name} from {submodule}"))?;
+    }
+
+    std::fs::create_dir_all(&marker_dir).with_context(|| {
+        format!(
+            "failed to create submodule marker directory {}",
+            marker_dir.display()
+        )
+    })?;
+    markers::mark_built(root, &marker_dir, name, submodule)?;
+    Ok(())
+}
+
+/// Returns the path to a cached release archive, downloading it when missing.
+///
+/// # Errors
+///
+/// Returns an error if the cache directory cannot be created or the download
+/// fails.
+pub(crate) fn ensure_cached_release_asset(
+    cache_dir: &Path,
+    asset_name: &str,
+    fetch: impl FnOnce() -> Result<Asset>,
+) -> Result<PathBuf> {
+    ensure_cached_release_asset_with(cache_dir, asset_name, fetch, github::download_asset)
+}
+
+pub(crate) fn ensure_cached_release_asset_with(
+    cache_dir: &Path,
+    asset_name: &str,
+    fetch: impl FnOnce() -> Result<Asset>,
+    download: impl FnOnce(&Asset, &Path) -> Result<()>,
+) -> Result<PathBuf> {
+    std::fs::create_dir_all(cache_dir)
+        .with_context(|| format!("failed to create cache dir {}", cache_dir.display()))?;
+
+    let archive = cache_dir.join(asset_name);
+    if !archive.exists() {
+        let asset = fetch()?;
+        println!("Downloading {asset_name}…");
+        download(&asset, &archive).with_context(|| format!("failed to download {asset_name}"))?;
+    } else {
+        println!("Using cached {asset_name}");
+    }
+
+    Ok(archive)
+}
+
+/// Extracts a cached archive, re-downloading once when extraction fails.
+///
+/// # Errors
+///
+/// Returns an error if download or extraction fails after one retry.
+pub(crate) fn extract_cached_archive<F>(
+    archive: &Path,
+    redownload: impl FnOnce() -> Result<()>,
+    extract: F,
+) -> Result<()>
+where
+    F: Fn(&Path) -> Result<()>,
+{
+    match extract(archive) {
+        Ok(()) => Ok(()),
+        Err(first) => {
+            std::fs::remove_file(archive).ok();
+            redownload().with_context(|| {
+                format!(
+                    "failed to re-download {} after corrupt cache",
+                    archive.display()
+                )
+            })?;
+            extract(archive).with_context(|| {
+                format!(
+                    "failed to extract {} after re-download: {first:#}",
+                    archive.display()
+                )
+            })
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::cell::Cell;
+    use std::fs;
+    use std::path::Path;
+
+    use super::*;
+    use crate::tasks::util::fs::extract_zip_matching_flat;
+    use crate::tasks::util::github::Asset;
+    use crate::tasks::util::workspace;
+
+    const GOOGLE_SUBMODULE: &str = "thirdparty/google-fonts";
+    const GOOGLE_MARKER: &str = "google-fonts";
+    const TEST_FILE: (&str, &str) = (
+        "VarelaRound-Regular.ttf",
+        "ofl/varelaround/VarelaRound-Regular.ttf",
+    );
+
+    fn write_test_zip(path: &Path, entries: &[(&str, &[u8])]) {
+        let file = std::fs::File::create(path).unwrap();
+        let mut writer = zip::ZipWriter::new(file);
+        let options = zip::write::SimpleFileOptions::default()
+            .compression_method(zip::CompressionMethod::Stored);
+
+        for (name, contents) in entries {
+            writer.start_file(*name, options).unwrap();
+            std::io::Write::write_all(&mut writer, contents).unwrap();
+        }
+
+        writer.finish().unwrap();
+    }
+
+    fn dummy_asset() -> Asset {
+        Asset {
+            browser_download_url: "https://example.com/asset.zip".to_owned(),
+            name: "asset.zip".to_owned(),
+            digest: None,
+        }
+    }
+
+    fn google_marker_dir(fonts_dir: &Path) -> PathBuf {
+        fonts_dir.join(format!(".markers/{GOOGLE_MARKER}"))
+    }
+
+    fn write_google_marker(fonts_dir: &Path, sha: &str) {
+        let marker_dir = google_marker_dir(fonts_dir);
+        fs::create_dir_all(&marker_dir).unwrap();
+        markers::mark_version(&marker_dir, GOOGLE_MARKER, sha).unwrap();
+    }
+
+    #[test]
+    fn extract_succeeds_on_valid_archive() {
+        let tmp = tempfile::tempdir().unwrap();
+        let archive = tmp.path().join("fonts.zip");
+        write_test_zip(&archive, &[("Libron-Regular.ttf", b"font")]);
+
+        let extract_dir = tmp.path().join("out");
+        extract_cached_archive(
+            &archive,
+            || Ok(()),
+            |path| extract_zip_matching_flat(path, &extract_dir, "", ".ttf"),
+        )
+        .unwrap();
+
+        assert!(archive.exists());
+        assert_eq!(
+            fs::read(extract_dir.join("Libron-Regular.ttf")).unwrap(),
+            b"font"
+        );
+    }
+
+    #[test]
+    fn extract_retries_after_corrupt_archive() {
+        let tmp = tempfile::tempdir().unwrap();
+        let archive = tmp.path().join("fonts.zip");
+        fs::write(&archive, b"not a zip").unwrap();
+
+        let extract_dir = tmp.path().join("out");
+        extract_cached_archive(
+            &archive,
+            || {
+                write_test_zip(&archive, &[("Libron-Regular.ttf", b"fresh")]);
+                Ok(())
+            },
+            |path| extract_zip_matching_flat(path, &extract_dir, "", ".ttf"),
+        )
+        .unwrap();
+
+        assert_eq!(
+            fs::read(extract_dir.join("Libron-Regular.ttf")).unwrap(),
+            b"fresh"
+        );
+    }
+
+    #[test]
+    fn ensure_cached_uses_existing_file() {
+        let tmp = tempfile::tempdir().unwrap();
+        let cache_dir = tmp.path().join("cache");
+        let asset_name = "other-core-fonts.zip";
+        let archive = cache_dir.join(asset_name);
+        fs::create_dir_all(&cache_dir).unwrap();
+        fs::write(&archive, b"cached").unwrap();
+
+        let fetch_called = Cell::new(false);
+        let path = ensure_cached_release_asset_with(
+            &cache_dir,
+            asset_name,
+            || {
+                fetch_called.set(true);
+                Ok(dummy_asset())
+            },
+            |_, _| Ok(()),
+        )
+        .unwrap();
+
+        assert_eq!(path, archive);
+        assert!(!fetch_called.get());
+        assert_eq!(fs::read(&archive).unwrap(), b"cached");
+    }
+
+    #[test]
+    fn ensure_cached_downloads_when_missing() {
+        let tmp = tempfile::tempdir().unwrap();
+        let cache_dir = tmp.path().join("cache");
+        let asset_name = "other-core-fonts.zip";
+        let fixture = tmp.path().join("fixture.zip");
+        write_test_zip(&fixture, &[("Libron-Regular.ttf", b"downloaded")]);
+
+        let fetch_called = Cell::new(false);
+        let path = ensure_cached_release_asset_with(
+            &cache_dir,
+            asset_name,
+            || {
+                fetch_called.set(true);
+                Ok(dummy_asset())
+            },
+            |_, dest| {
+                fs::copy(&fixture, dest)?;
+                Ok(())
+            },
+        )
+        .unwrap();
+
+        assert!(fetch_called.get());
+        assert_eq!(path, cache_dir.join(asset_name));
+        assert!(path.exists());
+    }
+
+    #[test]
+    fn is_submodule_install_current_false_without_files() {
+        let root = workspace::root().unwrap();
+        let sha = markers::submodule_commit(&root, GOOGLE_SUBMODULE).unwrap();
+        let fonts_dir = tempfile::tempdir().unwrap();
+        write_google_marker(fonts_dir.path(), &sha);
+
+        assert!(!is_submodule_install_current(
+            &root,
+            fonts_dir.path(),
+            GOOGLE_SUBMODULE,
+            GOOGLE_MARKER,
+            &[TEST_FILE],
+        ));
+    }
+
+    #[test]
+    fn is_submodule_install_current_false_with_stale_marker() {
+        let root = workspace::root().unwrap();
+        let fonts_dir = tempfile::tempdir().unwrap();
+        fs::write(fonts_dir.path().join(TEST_FILE.0), b"font").unwrap();
+        write_google_marker(fonts_dir.path(), "0".repeat(40).as_str());
+
+        assert!(!is_submodule_install_current(
+            &root,
+            fonts_dir.path(),
+            GOOGLE_SUBMODULE,
+            GOOGLE_MARKER,
+            &[TEST_FILE],
+        ));
+    }
+
+    #[test]
+    #[ignore = "requires initialized thirdparty/google-fonts submodule"]
+    fn install_from_submodule_copies_and_skips() {
+        let root = workspace::root().unwrap();
+        let fonts_dir = tempfile::tempdir().unwrap();
+        let files = &[TEST_FILE];
+
+        install_from_submodule(
+            &root,
+            GOOGLE_SUBMODULE,
+            fonts_dir.path(),
+            GOOGLE_MARKER,
+            files,
+        )
+        .unwrap();
+        assert!(fonts_dir.path().join(TEST_FILE.0).exists());
+
+        fs::write(fonts_dir.path().join(TEST_FILE.0), b"junk").unwrap();
+        install_from_submodule(
+            &root,
+            GOOGLE_SUBMODULE,
+            fonts_dir.path(),
+            GOOGLE_MARKER,
+            files,
+        )
+        .unwrap();
+        assert_eq!(
+            fs::read(fonts_dir.path().join(TEST_FILE.0)).unwrap(),
+            b"junk"
+        );
+        assert!(is_submodule_install_current(
+            &root,
+            fonts_dir.path(),
+            GOOGLE_SUBMODULE,
+            GOOGLE_MARKER,
+            files,
+        ));
+    }
+
+    #[test]
+    #[ignore = "requires initialized thirdparty/google-fonts submodule"]
+    fn install_from_submodule_removes_stale_dest_on_revision_change() {
+        let root = workspace::root().unwrap();
+        let fonts_dir = tempfile::tempdir().unwrap();
+        let files = &[TEST_FILE];
+        let expected = fs::read(root.join(GOOGLE_SUBMODULE).join(TEST_FILE.1)).unwrap();
+
+        install_from_submodule(
+            &root,
+            GOOGLE_SUBMODULE,
+            fonts_dir.path(),
+            GOOGLE_MARKER,
+            files,
+        )
+        .unwrap();
+
+        write_google_marker(fonts_dir.path(), "0".repeat(40).as_str());
+        fs::write(fonts_dir.path().join(TEST_FILE.0), b"junk").unwrap();
+
+        install_from_submodule(
+            &root,
+            GOOGLE_SUBMODULE,
+            fonts_dir.path(),
+            GOOGLE_MARKER,
+            files,
+        )
+        .unwrap();
+
+        assert_eq!(
+            fs::read(fonts_dir.path().join(TEST_FILE.0)).unwrap(),
+            expected
+        );
+    }
+}
diff --git a/xtask/src/tasks/mod.rs b/xtask/src/tasks/mod.rs
index 6d5d3e34..5c482519 100644
--- a/xtask/src/tasks/mod.rs
+++ b/xtask/src/tasks/mod.rs
@@ -11,6 +11,7 @@ pub mod clippy;
 pub mod dist;
 pub mod docs;
 pub mod download_assets;
+pub mod download_fonts;
 pub mod fmt;
 pub mod install_importer;
 pub mod run_emulator;
diff --git a/xtask/src/tasks/util/fs.rs b/xtask/src/tasks/util/fs.rs
index 54b4eeb1..baa287de 100644
--- a/xtask/src/tasks/util/fs.rs
+++ b/xtask/src/tasks/util/fs.rs
@@ -289,6 +289,105 @@ pub fn extract_zip_paths(src: &Path, dest_dir: &Path, prefixes: &[&str]) -> Resu
     Ok(())
 }
 
+/// Extracts zip entries whose basename matches `prefix` and `suffix` into
+/// `dest_dir` using only the filename (no nested directories).
+///
+/// Existing destination files are skipped.
+///
+/// # Errors
+///
+/// Returns an error if the archive cannot be read or a matched entry fails to
+/// extract.
+pub fn extract_zip_matching_flat(
+    src: &Path,
+    dest_dir: &Path,
+    prefix: &str,
+    suffix: &str,
+) -> Result<()> {
+    std::fs::create_dir_all(dest_dir).with_context(|| {
+        format!(
+            "failed to create destination directory {}",
+            dest_dir.display()
+        )
+    })?;
+
+    let file = std::fs::File::open(src)
+        .with_context(|| format!("failed to open archive {}", src.display()))?;
+    let mut archive = zip::ZipArchive::new(file)
+        .with_context(|| format!("failed to read zip {}", src.display()))?;
+
+    for i in 0..archive.len() {
+        let mut entry = archive
+            .by_index(i)
+            .with_context(|| format!("failed to read entry {i} from {}", src.display()))?;
+        let name = entry.name().to_owned();
+        if entry.is_dir() {
+            continue;
+        }
+        let Some(filename) = Path::new(&name).file_name().and_then(|n| n.to_str()) else {
+            continue;
+        };
+        if !filename.starts_with(prefix) || !filename.ends_with(suffix) {
+            continue;
+        }
+        let dest = dest_dir.join(filename);
+        if dest.exists() {
+            continue;
+        }
+        let mut out = std::fs::File::create(&dest)
+            .with_context(|| format!("failed to create file {}", dest.display()))?;
+        std::io::copy(&mut entry, &mut out)
+            .with_context(|| format!("failed to write {}", dest.display()))?;
+    }
+
+    Ok(())
+}
+
+/// Extracts named zip entries into `dest_dir`, optionally renaming on extract.
+///
+/// Each `entries` pair is `(path_inside_zip, dest_filename)`.  Existing
+/// destination files are skipped.
+///
+/// # Errors
+///
+/// Returns an error if the archive cannot be read, an entry is missing, or
+/// extraction fails.
+pub fn extract_zip_entries_flat(
+    src: &Path,
+    dest_dir: &Path,
+    entries: &[(impl AsRef<str>, impl AsRef<str>)],
+) -> Result<()> {
+    std::fs::create_dir_all(dest_dir).with_context(|| {
+        format!(
+            "failed to create destination directory {}",
+            dest_dir.display()
+        )
+    })?;
+
+    let file = std::fs::File::open(src)
+        .with_context(|| format!("failed to open archive {}", src.display()))?;
+    let mut archive = zip::ZipArchive::new(file)
+        .with_context(|| format!("failed to read zip {}", src.display()))?;
+
+    for (zip_path, dest_name) in entries {
+        let zip_path = zip_path.as_ref();
+        let dest_name = dest_name.as_ref();
+        let dest = dest_dir.join(dest_name);
+        if dest.exists() {
+            continue;
+        }
+        let mut entry = archive
+            .by_name(zip_path)
+            .with_context(|| format!("entry '{zip_path}' not found in {}", src.display()))?;
+        let mut out = std::fs::File::create(&dest)
+            .with_context(|| format!("failed to create file {}", dest.display()))?;
+        std::io::copy(&mut entry, &mut out)
+            .with_context(|| format!("failed to write {}", dest.display()))?;
+    }
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -407,4 +506,140 @@ mod tests {
         assert!(extract_dir.join("libs/libfoo.so").exists());
         assert!(!extract_dir.join("other/skip.txt").exists());
     }
+
+    fn write_test_zip(path: &Path, entries: &[(&str, &[u8])]) {
+        let file = std::fs::File::create(path).unwrap();
+        let mut writer = zip::ZipWriter::new(file);
+        let options = zip::write::SimpleFileOptions::default()
+            .compression_method(zip::CompressionMethod::Stored);
+
+        for (name, contents) in entries {
+            writer.start_file(*name, options).unwrap();
+            std::io::Write::write_all(&mut writer, contents).unwrap();
+        }
+
+        writer.finish().unwrap();
+    }
+
+    #[test]
+    fn extract_zip_matching_flat_extracts_matching_basenames() {
+        let tmp = tempfile::tempdir().unwrap();
+
+        let zip_path = tmp.path().join("fonts.zip");
+        write_test_zip(
+            &zip_path,
+            &[
+                ("nested/KF-Libron-Regular.otf", b"libron"),
+                ("nested/KF-Libron-Bold.otf", b"bold"),
+                ("nested/Other-Regular.otf", b"other"),
+                ("readme.txt", b"skip"),
+            ],
+        );
+
+        let extract_dir = tmp.path().join("fonts");
+        extract_zip_matching_flat(&zip_path, &extract_dir, "KF-Libron", ".otf").unwrap();
+
+        assert_eq!(
+            fs::read(extract_dir.join("KF-Libron-Regular.otf")).unwrap(),
+            b"libron"
+        );
+        assert_eq!(
+            fs::read(extract_dir.join("KF-Libron-Bold.otf")).unwrap(),
+            b"bold"
+        );
+        assert!(!extract_dir.join("Other-Regular.otf").exists());
+        assert!(!extract_dir.join("readme.txt").exists());
+    }
+
+    #[test]
+    fn extract_zip_matching_flat_skips_existing_files() {
+        let tmp = tempfile::tempdir().unwrap();
+
+        let zip_path = tmp.path().join("fonts.zip");
+        write_test_zip(&zip_path, &[("nested/KF-Libron-Regular.otf", b"new")]);
+
+        let extract_dir = tmp.path().join("fonts");
+        fs::create_dir_all(&extract_dir).unwrap();
+        fs::write(extract_dir.join("KF-Libron-Regular.otf"), b"existing").unwrap();
+
+        extract_zip_matching_flat(&zip_path, &extract_dir, "KF-Libron", ".otf").unwrap();
+
+        assert_eq!(
+            fs::read(extract_dir.join("KF-Libron-Regular.otf")).unwrap(),
+            b"existing"
+        );
+    }
+
+    #[test]
+    fn extract_zip_entries_flat_extracts_and_renames_entries() {
+        let tmp = tempfile::tempdir().unwrap();
+
+        let zip_path = tmp.path().join("release.zip");
+        write_test_zip(
+            &zip_path,
+            &[
+                ("SourceCodePro-Regular.otf", b"regular"),
+                ("SourceCodePro-Bold.otf", b"bold"),
+            ],
+        );
+
+        let extract_dir = tmp.path().join("fonts");
+        extract_zip_entries_flat(
+            &zip_path,
+            &extract_dir,
+            &[
+                ("SourceCodePro-Regular.otf", "Source Code Pro Regular.otf"),
+                ("SourceCodePro-Bold.otf", "Source Code Pro Bold.otf"),
+            ],
+        )
+        .unwrap();
+
+        assert_eq!(
+            fs::read(extract_dir.join("Source Code Pro Regular.otf")).unwrap(),
+            b"regular"
+        );
+        assert_eq!(
+            fs::read(extract_dir.join("Source Code Pro Bold.otf")).unwrap(),
+            b"bold"
+        );
+    }
+
+    #[test]
+    fn extract_zip_entries_flat_skips_existing_files() {
+        let tmp = tempfile::tempdir().unwrap();
+
+        let zip_path = tmp.path().join("release.zip");
+        write_test_zip(&zip_path, &[("SourceCodePro-Regular.otf", b"new")]);
+
+        let extract_dir = tmp.path().join("fonts");
+        fs::create_dir_all(&extract_dir).unwrap();
+        fs::write(extract_dir.join("Source Code Pro Regular.otf"), b"existing").unwrap();
+
+        extract_zip_entries_flat(
+            &zip_path,
+            &extract_dir,
+            &[("SourceCodePro-Regular.otf", "Source Code Pro Regular.otf")],
+        )
+        .unwrap();
+
+        assert_eq!(
+            fs::read(extract_dir.join("Source Code Pro Regular.otf")).unwrap(),
+            b"existing"
+        );
+    }
+
+    #[test]
+    fn extract_zip_entries_flat_errors_on_missing_entry() {
+        let tmp = tempfile::tempdir().unwrap();
+
+        let zip_path = tmp.path().join("release.zip");
+        write_test_zip(&zip_path, &[("SourceCodePro-Regular.otf", b"regular")]);
+
+        let extract_dir = tmp.path().join("fonts");
+        let err =
+            extract_zip_entries_flat(&zip_path, &extract_dir, &[("missing.otf", "missing.otf")])
+                .unwrap_err();
+
+        assert!(err.to_string().contains("entry 'missing.otf' not found"));
+    }
 }
diff --git a/xtask/src/tasks/util/github.rs b/xtask/src/tasks/util/github.rs
index dfc280f5..8a95c0e2 100644
--- a/xtask/src/tasks/util/github.rs
+++ b/xtask/src/tasks/util/github.rs
@@ -15,7 +15,7 @@
 //! avoids 403 rate-limit errors in GitHub Actions where the token is always
 //! available.
 
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use anyhow::{Context, Result};
 use serde::Deserialize;
@@ -24,7 +24,7 @@ use serde::Deserialize;
 /// when available, an `Authorization: Bearer` token from the environment.
 ///
 /// Checks `GH_TOKEN` first, then `GITHUB_TOKEN`.
-fn client() -> Result<reqwest::blocking::Client> {
+pub(crate) fn client() -> Result<reqwest::blocking::Client> {
     let mut builder = reqwest::blocking::Client::builder().user_agent("cargo-xtask/cadmus");
 
     if let Some(token) = std::env::var("GH_TOKEN")
@@ -157,6 +157,12 @@ pub fn download_asset(asset: &Asset, dest: &Path) -> Result<()> {
             .with_context(|| format!("failed to create parent directory for {}", dest.display()))?;
     }
 
+    let temp = {
+        let mut path = dest.as_os_str().to_os_string();
+        path.push(".part");
+        PathBuf::from(path)
+    };
+
     let bytes = client()?
         .get(&asset.browser_download_url)
         .send()
@@ -176,8 +182,15 @@ pub fn download_asset(asset: &Asset, dest: &Path) -> Result<()> {
             )
         })?;
 
-    std::fs::write(dest, &bytes)
-        .with_context(|| format!("failed to write downloaded file to {}", dest.display()))
+    std::fs::write(&temp, &bytes)
+        .with_context(|| format!("failed to write downloaded file to {}", temp.display()))?;
+    std::fs::rename(&temp, dest).with_context(|| {
+        format!(
+            "failed to move downloaded file from {} to {}",
+            temp.display(),
+            dest.display()
+        )
+    })
 }
 
 fn fetch_release_from_url(url: &str) -> Result<Release> {