diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5b6407a..1a12a3e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,19 +8,30 @@ on:
 jobs:
   build:
     name: build (${{ matrix.platform }})
-    runs-on: ${{ matrix.runs-on }}
+    runs-on: ${{ (github.repository == 'commaai/dependencies' && (github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == 'commaai/dependencies')) && matrix.runs-on-namespace || matrix.runs-on }}
     strategy:
       fail-fast: false
       matrix:
         include:
           - platform: linux-x86_64
             runs-on: ubuntu-latest
+            runs-on-namespace: namespace-profile-amd64-8x16
           - platform: linux-arm64
             runs-on: ubuntu-24.04-arm
+            runs-on-namespace: namespace-profile-arm64-big
           - platform: macos
             runs-on: macos-latest
+            runs-on-namespace: namespace-profile-macos-8x14
     steps:
       - uses: actions/checkout@v6
+      - name: Select Xcode 16
+        if: runner.os == 'macOS'
+        run: |
+          XCODE=$(ls -d /Applications/Xcode_16*.app 2>/dev/null | sort -V | tail -1)
+          if [ -n "$XCODE" ]; then
+            echo "Selected: $XCODE"
+            sudo xcode-select -s "$XCODE"
+          fi
       - uses: actions/cache@v4
         with:
           key: build-cache-v2-${{ matrix.platform }}-${{ hashFiles('build.sh', 'setup.sh', '*/pyproject.toml', '*/setup.py', '*/build.sh') }}
diff --git a/build.sh b/build.sh
index 8b6b3d3..1e32c7e 100755
--- a/build.sh
+++ b/build.sh
@@ -48,6 +48,15 @@ if [[ -n "${BUILD_SH_IN_MANYLINUX:-}" ]]; then
       rm -rf "$pkg/$module/install" "$pkg/$module/toolchain" "$pkg/$module/bin"
     done
   fi
+
+  # Install all manylinux system deps upfront — individual build.sh scripts
+  # run in parallel via uv, so concurrent dnf calls would race on the cache.
+  if command -v dnf &>/dev/null; then
+    dnf install -y -q \
+      libX11-devel libXcursor-devel libXrandr-devel libXinerama-devel libXi-devel \
+      mesa-libGL-devel wayland-devel wayland-protocols-devel libxkbcommon-devel \
+      xorg-x11-server-Xvfb xorg-x11-xkb-utils xkeyboard-config
+  fi
 fi
 
 export CMAKE_C_COMPILER_LAUNCHER=ccache
diff --git a/imgui/build.sh b/imgui/build.sh
index 5c3b93a..0eb0978 100755
--- a/imgui/build.sh
+++ b/imgui/build.sh
@@ -39,12 +39,9 @@ fi
 git -C glfw-src fetch --depth 1 origin "$GLFW_COMMIT"
 git -C glfw-src checkout --force "$GLFW_COMMIT"
 
-# Install GLFW build dependencies
+# Install GLFW build dependencies (manylinux deps installed centrally in build.sh)
 if [[ "$(uname)" == "Linux" ]]; then
-  if command -v dnf &>/dev/null; then
-    dnf install -y libX11-devel libXcursor-devel libXrandr-devel libXinerama-devel libXi-devel mesa-libGL-devel \
-                   wayland-devel wayland-protocols-devel libxkbcommon-devel
-  elif command -v apt-get &>/dev/null; then
+  if command -v apt-get &>/dev/null; then
     if [ "$(id -u)" -eq 0 ]; then
       apt-get update && apt-get install -y libxcursor-dev libxi-dev libxinerama-dev libxrandr-dev libgl-dev \
                                            libwayland-dev wayland-protocols libxkbcommon-dev