diff --git a/.gitignore b/.gitignore
index a666135..008bea8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,9 @@ bin/
 lib/
 obj/
 
+# Flatpak
+.flatpak-builder/
+
 # Prerequisites
 *.d
 
diff --git a/AGENTS.md b/AGENTS.md
index 26f56bb..0b0b4a9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -30,6 +30,8 @@ meson compile -C build
 - Version `1.0.0` is stamped in FOUR places: `meson.build`, `flake.nix`, `default.nix`, and the `<releases>` entry in `resources/io.github.bemagri.nomines.metainfo.xml`. Bump all four together.
 - Release sanity: `nix build .` (validates the flake), `desktop-file-validate` + `appstreamcli validate --no-net` on the resources (wired up as meson tests).
 - The metainfo screenshot URL points at `raw.githubusercontent.com/bemagri/nomines/main/...` — it 404s until the repo is published; replace if the repo moves.
+- Flatpak: `io.github.bemagri.nomines.yml` builds libsigc++/glibmm/cairomm/pangomm/gtkmm from tarballs against the GNOME 46 runtime (matches the gtkmm 4.14/glib 2.80 stack we develop against), then the app from the `v1.0.0` git tag. The pinned `commit:` must match the pushed tag. The leaderboard needs the `--filesystem=xdg-config/nomines:create` finish-arg — don't drop it. Local builds land in `.flatpak-builder/` (gitignored); `flatpak-builder --user --install --force-clean build-flatpak io.github.bemagri.nomines.yml`.
+- Flatpak module version traps (all verified by building): gtkmm 4.14 needs pangomm >= 2.50 (which still installs `pangomm-2.48.pc`; 2.48.x is too old), and cairomm tarballs live on `cairographics.org/releases`, not download.gnome.org. `appstream-compose: false` is set in the manifest because flatpak-builder's compose fetches the (still-404) metainfo screenshot URL — remove it once the repo is public. Flatpak's icon validation can't decode SVGs, so PNG icons (128/512) are installed under the app-id name and the svg is cleanup-removed; keep that convention.
 
 ## Gotchas
 
diff --git a/README.md b/README.md
index 2c09fe5..617e6ff 100644
--- a/README.md
+++ b/README.md
@@ -100,6 +100,20 @@ The Nix flake also provides a development shell with all dependencies:
 nix develop
 ```
 
+## Building a Flatpak
+
+NoMines ships a Flatpak manifest (`io.github.bemagri.nomines.yml`) that builds
+the gtkmm stack (libsigc++, glibmm, gtkmm) against the GNOME 46 runtime:
+
+```bash
+flatpak install -y flathub org.gnome.Platform//46 org.gnome.Sdk//46
+flatpak-builder --user --install --force-clean build-flatpak io.github.bemagri.nomines.yml
+flatpak run io.github.bemagri.nomines
+```
+
+Note: the manifest's `commit` must match the pushed `v1.0.0` tag (update it if
+the history is rebased before pushing).
+
 ## Contributing
 
 Contributions are welcome! Please feel free to submit a Pull Request.
diff --git a/io.github.bemagri.nomines.yml b/io.github.bemagri.nomines.yml
new file mode 100644
index 0000000..7362284
--- /dev/null
+++ b/io.github.bemagri.nomines.yml
@@ -0,0 +1,112 @@
+# Flatpak manifest for NoMines.
+#
+# The GNOME runtime pins the exact gtk4/glib versions the gtkmm stack is
+# built against: 46 = gtk 4.14 + glib 2.80, matching gtkmm 4.14/glibmm 2.80.
+#
+# Build locally:
+#   flatpak install -y flathub org.gnome.Platform//46 org.gnome.Sdk//46
+#   flatpak-builder --user --install --force-clean build-flatpak io.github.bemagri.nomines.yml
+#   flatpak run io.github.bemagri.nomines
+
+app-id: io.github.bemagri.nomines
+runtime: org.gnome.Platform
+runtime-version: '46'
+sdk: org.gnome.Sdk
+command: nomines
+
+# flatpak-builder's appstreamcli compose fetches the metainfo screenshot URL;
+# it 404s until the repo is published. Remove this line once the repo is
+# public (Flathub CI runs its own compose/validation anyway).
+appstream-compose: false
+
+finish-args:
+  - --share=ipc
+  - --socket=fallback-x11
+  - --socket=wayland
+  - --device=dri
+  # Leaderboard persistence (~/.config/nomines/leaderboard.ini)
+  - --filesystem=xdg-config/nomines:create
+
+build-options:
+  no-debuginfo: true
+
+cleanup:
+  - /include
+  - /lib/pkgconfig
+  - /lib/cmake
+  - /lib/girepository-1.0
+  - /lib/*.a
+  - /lib/*.la
+  - /share/aclocal
+  - /share/doc
+  - /share/gir-1.0
+  - /share/gtk-doc
+  - /share/pkgconfig
+  # flatpak's icon validation can't decode SVGs; the PNGs suffice
+  - /share/icons/hicolor/scalable/apps/*.svg
+
+modules:
+  - name: libsigc++
+    buildsystem: meson
+    config-opts:
+      - -Dbuild-tests=false
+      - -Dbuild-examples=false
+    sources:
+      - type: archive
+        url: https://download.gnome.org/sources/libsigc++/3.6/libsigc++-3.6.0.tar.xz
+        sha256: c3d23b37dfd6e39f2e09f091b77b1541fbfa17c4f0b6bf5c89baef7229080e17
+
+  - name: glibmm
+    buildsystem: meson
+    config-opts:
+      - -Dmaintainer-mode=false
+      - -Dbuild-documentation=false
+      - -Dbuild-examples=false
+    sources:
+      - type: archive
+        url: https://download.gnome.org/sources/glibmm/2.80/glibmm-2.80.0.tar.xz
+        sha256: 539b0a29e15a96676c4f0594541250566c5ca44da5d4d87a3732fa2d07909e4a
+
+  - name: cairomm
+    buildsystem: meson
+    config-opts:
+      - -Dmaintainer-mode=false
+      - -Dbuild-documentation=false
+      - -Dbuild-examples=false
+      - -Dbuild-tests=false
+    sources:
+      - type: archive
+        url: https://www.cairographics.org/releases/cairomm-1.16.2.tar.xz
+        sha256: 6a63bf98a97dda2b0f55e34d1b5f3fb909ef8b70f9b8d382cb1ff3978e7dc13f
+
+  - name: pangomm
+    buildsystem: meson
+    config-opts:
+      - -Dmaintainer-mode=false
+      - -Dbuild-documentation=false
+    sources:
+      - type: archive
+        # gtkmm 4.14 needs pangomm >= 2.50.0 (which still installs the
+        # pangomm-2.48.pc name). 2.48.x is too old.
+        url: https://download.gnome.org/sources/pangomm/2.50/pangomm-2.50.2.tar.xz
+        sha256: 1bc5ab4ea3280442580d68318226dab36ceedfc3288f9d83711cf7cfab50a9fb
+
+  - name: gtkmm
+    buildsystem: meson
+    config-opts:
+      - -Dmaintainer-mode=false
+      - -Dbuild-documentation=false
+      - -Dbuild-demos=false
+      - -Dbuild-tests=false
+    sources:
+      - type: archive
+        url: https://download.gnome.org/sources/gtkmm/4.14/gtkmm-4.14.0.tar.xz
+        sha256: 9350a0444b744ca3dc69586ebd1b6707520922b6d9f4f232103ce603a271ecda
+
+  - name: nomines
+    buildsystem: meson
+    sources:
+      - type: git
+        url: https://github.com/bemagri/nomines
+        tag: v1.0.0
+        commit: 2dbf64a2e8c9bf828d69a4fc27f2af1bbfa780f2
diff --git a/meson.build b/meson.build
index e86beea..030954d 100644
--- a/meson.build
+++ b/meson.build
@@ -37,10 +37,22 @@ executable('nomines',
     install : true
 )
 
-# Install icon
+# Install icon (named after the app id so flatpak export picks it up;
+# PNG sizes are required by flatpak/flathub icon validation)
 install_data(
     'resources/nomines.svg',
-    install_dir: join_paths(get_option('datadir'), 'icons/hicolor/scalable/apps')
+    install_dir: join_paths(get_option('datadir'), 'icons/hicolor/scalable/apps'),
+    rename: 'io.github.bemagri.nomines.svg'
+)
+install_data(
+    'resources/nomines-128.png',
+    install_dir: join_paths(get_option('datadir'), 'icons/hicolor/128x128/apps'),
+    rename: 'io.github.bemagri.nomines.png'
+)
+install_data(
+    'resources/nomines-512.png',
+    install_dir: join_paths(get_option('datadir'), 'icons/hicolor/512x512/apps'),
+    rename: 'io.github.bemagri.nomines.png'
 )
 
 # Install desktop file
diff --git a/resources/io.github.bemagri.nomines.desktop b/resources/io.github.bemagri.nomines.desktop
index 4cb4394..f33e95d 100644
--- a/resources/io.github.bemagri.nomines.desktop
+++ b/resources/io.github.bemagri.nomines.desktop
@@ -4,7 +4,7 @@ GenericName=Minesweeper Game
 Comment=Classic minesweeper game with modern GTK UI
 Keywords=game;puzzle;mine;
 Exec=nomines
-Icon=nomines
+Icon=io.github.bemagri.nomines
 Terminal=false
 Type=Application
 Categories=Game;LogicGame;
diff --git a/resources/nomines-128.png b/resources/nomines-128.png
new file mode 100644
index 0000000..c2f2488
Binary files /dev/null and b/resources/nomines-128.png differ
diff --git a/resources/nomines-512.png b/resources/nomines-512.png
new file mode 100644
index 0000000..5f89294
Binary files /dev/null and b/resources/nomines-512.png differ