diff --git a/tools/chatgui/build.sh b/tools/chatgui/build.sh
index c8b42f711..b09366fc9 100755
--- a/tools/chatgui/build.sh
+++ b/tools/chatgui/build.sh
@@ -29,6 +29,7 @@ while [[ $# -gt 0 ]]; do
 done
 [[ "$JOBS" =~ ^[1-9][0-9]*$ ]] || { log "ERROR: invalid job count: $JOBS"; exit 1; }
 CMAKE_ARGS=()
+bash "$SRC_DIR/install_deps_win.sh" 2>&1 | tee -a "$LOG_FILE"
 if [[ "$BUILD_INSTALLER" = 1 ]]; then
     bash "$SRC_DIR/package_win.sh" --check 2>&1 | tee -a "$LOG_FILE"
     CMAKE_ARGS+=(-DCMAKE_BUILD_TYPE=Release)
diff --git a/tools/chatgui/build_nix.sh b/tools/chatgui/build_nix.sh
index b0e826e5c..59ea67e10 100755
--- a/tools/chatgui/build_nix.sh
+++ b/tools/chatgui/build_nix.sh
@@ -56,9 +56,9 @@ install_deps() {
     if [ "$OS_ID" = linux ]; then
         sudo apt-get update
         sudo apt-get install -y build-essential cmake qt6-base-dev qt6-multimedia-dev qt6-image-formats-plugins qt6-tools-dev-tools qt6-translations-l10n librlottie-dev zlib1g-dev libssl-dev \
-            libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libswresample-dev
+            libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libswresample-dev libkf6syntaxhighlighting-dev
     else
-        sudo pkg install -y cmake qt6-base qt6-multimedia qt6-tools qt6-translations rlottie openssl ffmpeg
+        sudo pkg install -y cmake qt6-base qt6-multimedia qt6-tools qt6-translations rlottie openssl ffmpeg kf6-syntax-highlighting
     fi
 }
 
diff --git a/tools/chatgui/install_deps_win.sh b/tools/chatgui/install_deps_win.sh
new file mode 100644
index 000000000..7bfcdafe6
--- /dev/null
+++ b/tools/chatgui/install_deps_win.sh
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Установить только отсутствующие пакеты GUI из UCRT64. При готовом окружении сеть не используется.
+set -euo pipefail
+
+[[ ${MSYSTEM:-} = UCRT64 ]] || { echo 'ERROR: GUI dependencies require MSYS2 UCRT64' >&2; exit 1; }
+command -v pacman >/dev/null || { echo 'ERROR: pacman not found; run the build from MSYS2 UCRT64' >&2; exit 1; }
+
+required=(make git curl patch tar xz)
+for name in gcc cmake ninja pkgconf openssl zlib qt6-base qt6-tools qt6-translations qt6-imageformats qt6-multimedia syntax-highlighting; do
+    required+=("mingw-w64-ucrt-x86_64-$name")
+done
+installed=$(pacman -Qq) || { echo 'ERROR: cannot query installed MSYS2 packages' >&2; exit 1; }
+declare -A present=()
+while IFS= read -r name; do [[ -z "$name" ]] || present["$name"]=1; done <<< "$installed"
+missing=()
+for name in "${required[@]}"; do [[ -n ${present[$name]:-} ]] || missing+=("$name"); done
+if (( ${#missing[@]} == 0 )); then
+    echo "INFO: GUI dependencies present (${#required[@]} packages); no installation needed"
+    exit 0
+fi
+
+echo "INFO: installing missing GUI dependencies (${#missing[@]}): ${missing[*]}"
+pacman -S --needed --noconfirm "${missing[@]}" || {
+    echo 'ERROR: dependency installation failed; check the pacman output. If repositories are outdated, run pacman -Syu and retry.' >&2
+    exit 1
+}
+pacman -Q "${required[@]}" >/dev/null || { echo 'ERROR: GUI dependencies still missing after installation' >&2; exit 1; }
+echo 'INFO: GUI dependencies installed'