default.nix

@@ -71,6 +71,7 @@ in
       wordpress-plugins
       wordpress-themes
       kubo
+      fcitx5
       ;
   }
   // (

flake.nix

@@ -115,6 +115,7 @@
               kubo
               hydra
               hydra-unstable
+              fcitx5
               ;
           }
           // (

i18n/fcitx5/gen-unicode-data.nix

@@ -0,0 +1,29 @@
+{
+  python3,
+  unicode-character-database,
+  unihan-database,
+  stdenv,
+}:
+stdenv.mkDerivation {
+  pname = "fcitx5-unicode-data";
+  inherit (unicode-character-database) version;
+
+  src = ./.;
+
+  nativeBuildInputs = [python3];
+
+  buildPhase = ''
+    cp ${unicode-character-database}/share/unicode/UnicodeData.txt .
+    cp ${unicode-character-database}/share/unicode/NamesList.txt .
+    cp ${unicode-character-database}/share/unicode/Blocks.txt .
+    cp ${unihan-database}/share/unicode/Unihan_Readings.txt .
+
+    python3 gen.py
+  '';
+
+  installPhase = ''
+    mkdir $out
+    cp kcharselect-data $out
+    cp kcharselect-translation.cpp $out
+  '';
+}

i18n/fcitx5/patched-source.nix

@@ -0,0 +1,18 @@
+{
+  fcitx5,
+  stdenv,
+  callPackage,
+}: let
+  unicode-data = callPackage ./gen-unicode-data.nix {};
+in
+  stdenv.mkDerivation {
+    pname = "fcitx5-src";
+    inherit (fcitx5) version src;
+
+    buildPhase = "true";
+    installPhase = ''
+      cp -r $src $out
+      chmod -R +w $out
+      cp ${unicode-data}/* $out/src/modules/unicode
+    '';
+  }

overlay.nix

@@ -85,6 +85,9 @@ system: self: super: let
       wordpress-plugins = self.callPackage ./web/wordpress-plugins {};
       wordpress-themes = self.callPackage ./web/wordpress-themes {};
       kubo = self.callPackage ./ipfs/kubo {};
+      fcitx5 = super.fcitx5.overrideAttrs (_: {
+        src = self.callPackage ./i18n/fcitx5/patched-source.nix {inherit (super) fcitx5;};
+      });
     })
     riscv-overlay
   ];