diff --git a/.github/scatterlab/android-prebuilt.md b/.github/scatterlab/android-prebuilt.md
index 812ae102866..c20884c5292 100644
--- a/.github/scatterlab/android-prebuilt.md
+++ b/.github/scatterlab/android-prebuilt.md
@@ -65,6 +65,7 @@ env ORG_GRADLE_PROJECT_react.internal.useHermesStable=true \
 - ABI는 기본값(`armeabi-v7a,arm64-v8a,x86,x86_64`)을 그대로 둔다. 소비자의 `reactNativeArchitectures`와 같아야 한다.
 - Debug·Release 두 variant는 `components.default` 멀티 variant 퍼블리시로 한 번에 나온다(`publish.gradle`).
 - 빌드는 **zeta 의 네이티브 Android 출고가 도는 러너**(`[self-hosted, zeta-app-builder]`)에서 돈다 — SDK·NDK·CMake 가 이미 있고 조직 TLS 프록시도 이미 신뢰한다. 상류처럼 `reactnativecommunity/react-native-android` 컨테이너를 쓰는 길은 막혀 있다: dind ARC 러너의 잡 컨테이너 안에서는 git 이 github.com 을 검증하지 못하고(조직이 자체 CA로 TLS를 종단한다), `volumes:` 로도 못 고친다 — dind는 **docker 데몬 쪽** 파일시스템을 마운트하지 그 CA를 가진 러너의 것을 마운트하지 않는다. `ANDROID_HOME` 은 `deploy-native.yml` 과 같은 값을 쓴다.
+- 러너의 Android SDK에 `cmake;3.30.5` 와 `ndk;27.1.12297006` 이 있어야 한다. zeta 앱 빌드는 prebuilt AAR을 링크할 뿐 ReactCommon을 컴파일하지 않아 이 둘을 쓸 일이 없었다. 워크플로가 `sdkmanager` 로 직접 설치하고 설치 여부를 디렉터리 존재로 확인한다 — 라벨 뒤에 머신이 여러 대라 손으로 깔면 한 대만 고쳐진다. 버전은 `libs.versions.toml`(ndkVersion)·`ReactAndroid/build.gradle.kts`(cmakeVersion)를 따르며 **base를 올릴 때 함께 맞춘다**.
 - ccache를 러너에 유지한다. 없으면 매 실행이 전체 C++ 재컴파일이다.
 - 빌드 산출물은 수 GB다. `if: always()`로 정리한다.
 
diff --git a/.github/workflows/scatterlab-prebuild-android.yml b/.github/workflows/scatterlab-prebuild-android.yml
index 758eec8f892..f9f5f4c199d 100644
--- a/.github/workflows/scatterlab-prebuild-android.yml
+++ b/.github/workflows/scatterlab-prebuild-android.yml
@@ -167,6 +167,38 @@ jobs:
 
       - uses: ./.github/actions/yarn-install
 
+      # zeta's app build links the prebuilt react-android AAR and never compiles
+      # ReactCommon, so nothing has ever needed these on this runner - the first real run
+      # died with `[CXX1300] CMake '3.30.5' was not found in SDK, PATH, or by cmake.dir
+      # property.` (run 34554813265). Installing here rather than by hand because the
+      # label carries several machines (runs landed on `actions-runner-a` and `runner-c`),
+      # so a manual install only fixes whichever one you were looking at.
+      #
+      # Versions must match packages/react-native/gradle/libs.versions.toml (ndkVersion)
+      # and ReactAndroid/build.gradle.kts (cmakeVersion) - upstream builds against that
+      # pair. sdkmanager is idempotent, so this is a no-op once a machine is warm.
+      - name: Ensure the CMake and NDK ReactAndroid builds against
+        run: |
+          set -euo pipefail
+          SDKMANAGER=""
+          for candidate in "$ANDROID_HOME"/cmdline-tools/latest/bin/sdkmanager \
+                           "$ANDROID_HOME"/cmdline-tools/*/bin/sdkmanager \
+                           "$ANDROID_HOME"/tools/bin/sdkmanager; do
+            if [ -x "$candidate" ]; then SDKMANAGER="$candidate"; break; fi
+          done
+          if [ -z "$SDKMANAGER" ]; then
+            echo "::error::No sdkmanager under $ANDROID_HOME. This runner cannot install the CMake/NDK ReactAndroid needs."
+            exit 1
+          fi
+          echo "sdkmanager: $SDKMANAGER"
+          yes 2>/dev/null | "$SDKMANAGER" --install 'cmake;3.30.5' 'ndk;27.1.12297006'
+          # Prove it landed rather than trusting sdkmanager's exit code, which stays 0 for
+          # a package it silently declined to install.
+          for required in "$ANDROID_HOME/cmake/3.30.5" "$ANDROID_HOME/ndk/27.1.12297006"; do
+            [ -d "$required" ] || { echo "::error::$required is still missing after sdkmanager ran"; exit 1; }
+          done
+          echo "cmake 3.30.5 and ndk 27.1.12297006 present"
+
       # Without a warm ccache every run is a full C++ rebuild of ReactCommon.
       # CCACHE_DIR is set explicitly: ccache's default differs per platform, and the cache
       # action needs the same path the compiler actually writes to.