diff --git a/.github/scripts/package-artifacts.sh b/.github/scripts/package-artifacts.sh
index e9771517..9e88fa87 100755
--- a/.github/scripts/package-artifacts.sh
+++ b/.github/scripts/package-artifacts.sh
@@ -21,10 +21,16 @@ echo "==> app.tar.gz from source (git archive HEAD)"
 git archive --format=tar.gz -o app.tar.gz HEAD \
   agent deploy langgraph.json pyproject.toml uv.lock README.md
 
+# List the archive ONCE into a variable. (`tar -tzf ... | grep -q ...` is unsafe
+# under `set -o pipefail`: grep -q exits on first match, SIGPIPEs tar -> "write
+# error" -> the pipeline reports non-zero even though grep succeeded, a false
+# failure. Listing once avoids the pipe entirely.)
+APP_LIST="$(tar -tzf app.tar.gz)"
+
 # Sanity: the box's `uv sync --frozen` needs pyproject.toml + uv.lock at the root,
 # and the package itself (agent/). Fail loudly here rather than on the box.
 for required in pyproject.toml uv.lock agent/server.py langgraph.json; do
-  tar -tzf app.tar.gz | grep -qx "${required}" || {
+  printf '%s\n' "${APP_LIST}" | grep -qx "${required}" || {
     echo "ERROR: app.tar.gz is missing ${required}" >&2
     exit 1
   }
@@ -36,9 +42,9 @@ done
 # extensions so credential-handling *source* (e.g. team_credentials.py) is not a
 # false positive.
 SECRET_RE='(^|/)(\.env(\..+)?|id_rsa|.*\.(pem|key|p12|pfx)|.*(secret|credential|password|token)s?\.(json|ya?ml|txt|env|ini|cfg))$'
-if tar -tzf app.tar.gz | grep -qiE "${SECRET_RE}"; then
+if printf '%s\n' "${APP_LIST}" | grep -qiE "${SECRET_RE}"; then
   echo "ERROR: app.tar.gz contains a secret-shaped file — refusing to publish:" >&2
-  tar -tzf app.tar.gz | grep -iE "${SECRET_RE}" >&2
+  printf '%s\n' "${APP_LIST}" | grep -iE "${SECRET_RE}" >&2
   exit 1
 fi