diff --git a/artifacts/runtime/env_sync.sh b/artifacts/runtime/env_sync.sh
index 8f8d75a78..a61c98800 100755
--- a/artifacts/runtime/env_sync.sh
+++ b/artifacts/runtime/env_sync.sh
@@ -67,6 +67,10 @@ sync_python_env() {
       && PYTHONPATH="$DIR" "$DIR/.venv/bin/python3" "$DIR/iqpilot/system/runtime_wheels_verify.py"; then
     RUNTIME_WHEELS_READY=1
   fi
+  if [ ! -f "$DIR/prebuilt" ] && [ ! -x "$DIR/.venv/bin/python3" ]; then
+    PACKAGES_READY=0
+    RUNTIME_WHEELS_READY=0
+  fi
   if [ "$PACKAGES_READY" != "1" ] || [ "$RUNTIME_WHEELS_READY" != "1" ]; then
     UV_CACHE_DIR="$DIR/.uv-cache"
     if [ ! -x "$DIR/.venv/bin/python3" ]; then
@@ -114,6 +118,9 @@ sync_python_env() {
       printf '%s\n' "$RUNTIME_WHEEL_LOCK_SHA" > "$DIR/.iqpilot-runtime-wheel-lock-sha256"
     fi
   fi
+  if [ ! -f "$DIR/prebuilt" ] && [ ! -x "$DIR/.venv/bin/python3" ]; then
+    return 1
+  fi
   if [ -n "$VENV_SITE_PACKAGES" ]; then
     printf 'import site; site.addsitedir("%s")\n' "$BASE_SITE_PACKAGES" | sudo tee "$VENV_SITE_PACKAGES/iqpilot-system-venv.pth" >/dev/null
   fi
diff --git a/launch_chffrplus.sh b/launch_chffrplus.sh
index 05b2a06a4..9dbb1cd3d 100755
--- a/launch_chffrplus.sh
+++ b/launch_chffrplus.sh
@@ -173,6 +173,9 @@ function launch {
   # for local dev edits or a failed apply-time prep, under the boot spinner as before.
   source "$DIR/artifacts/runtime/env_sync.sh"
   sync_python_env || return 1
+  if [ ! -f "$DIR/prebuilt" ] && [ ! -x "$DIR/.venv/bin/python3" ]; then
+    return 1
+  fi
   export PATH="$DIR/.venv/bin:$PATH"
 
   RUNTIME_COMPAT_ROOT="$DIR/.iqpilot/runtime_root"