diff --git a/actions/setup/sh/create_gh_aw_tmp_dir.sh b/actions/setup/sh/create_gh_aw_tmp_dir.sh
index 1e5d9323963..1639c17eee4 100755
--- a/actions/setup/sh/create_gh_aw_tmp_dir.sh
+++ b/actions/setup/sh/create_gh_aw_tmp_dir.sh
@@ -34,4 +34,37 @@ mkdir -p /tmp/gh-aw/sandbox/agent/logs
 # rather than deep inside AWF, surfacing the problem at an earlier step.
 mkdir -p /tmp/gh-aw/sandbox/firewall/logs
 mkdir -p /tmp/gh-aw/sandbox/firewall/audit
+
+# Rootless AWF writes per-run chroot files (including generated /etc/hosts) under
+# os.tmpdir(). Pin TMPDIR to a runner-owned subtree so writeConfigs never lands in a
+# stale root-owned /tmp/awf-* path on persistent runners.
+if [ -d /tmp/gh-aw/awf-tmp ] && [ ! -w /tmp/gh-aw/awf-tmp ]; then
+  echo "Pre-flight: /tmp/gh-aw/awf-tmp is not writable; reclaiming with sudo"
+  if command -v sudo >/dev/null 2>&1; then
+    sudo -n rm -rf /tmp/gh-aw/awf-tmp 2>/dev/null || echo "::warning::sudo rm failed for /tmp/gh-aw/awf-tmp; gh-aw may fail with permission errors. Try: sudo rm -rf /tmp/gh-aw/awf-tmp"
+  else
+    echo "::warning::sudo unavailable; cannot reclaim /tmp/gh-aw/awf-tmp; gh-aw may fail with permission errors. Remove /tmp/gh-aw/awf-tmp with admin privileges."
+  fi
+fi
+mkdir -p /tmp/gh-aw/awf-tmp
+
+# Fast pre-flight probe: fail early with a clear message if AWF's temp root can't
+# create/write the chroot hosts file it needs during config generation.
+AWF_CHROOT_PROBE_DIR="$(mktemp -d /tmp/gh-aw/awf-tmp/chroot-preflight-XXXXXX)"
+if ! printf '127.0.0.1 localhost\n' > "${AWF_CHROOT_PROBE_DIR}/hosts"; then
+  echo "::error::Pre-flight check failed: cannot write to /tmp/gh-aw/awf-tmp."
+  echo "::error::Check directory ownership and remove stale directories (for example: sudo rm -rf /tmp/gh-aw/awf-tmp)."
+  exit 1
+fi
+rm -rf "${AWF_CHROOT_PROBE_DIR}"
+
+# Persist TMPDIR for subsequent workflow steps (including Execute GitHub Copilot CLI).
+if [ -n "${GITHUB_ENV:-}" ]; then
+  {
+    echo "TMPDIR=/tmp/gh-aw/awf-tmp"
+    echo "TMP=/tmp/gh-aw/awf-tmp"
+    echo "TEMP=/tmp/gh-aw/awf-tmp"
+  } >> "${GITHUB_ENV}"
+fi
+
 echo "Created /tmp/gh-aw/agent directory for agentic workflow temporary files"
diff --git a/actions/setup/sh/create_gh_aw_tmp_dir_test.sh b/actions/setup/sh/create_gh_aw_tmp_dir_test.sh
index 089c03fa4e9..930258a467a 100644
--- a/actions/setup/sh/create_gh_aw_tmp_dir_test.sh
+++ b/actions/setup/sh/create_gh_aw_tmp_dir_test.sh
@@ -46,6 +46,7 @@ bash "${SCRIPT}" >/dev/null 2>&1
 assert "creates /tmp/gh-aw/agent" "[ -d /tmp/gh-aw/agent ]"
 assert "creates /tmp/gh-aw/sandbox/firewall/logs" "[ -d /tmp/gh-aw/sandbox/firewall/logs ]"
 assert "creates /tmp/gh-aw/sandbox/firewall/audit" "[ -d /tmp/gh-aw/sandbox/firewall/audit ]"
+assert "creates /tmp/gh-aw/awf-tmp" "[ -d /tmp/gh-aw/awf-tmp ]"
 echo ""
 
 # ── Test 3: No-op when firewall dir already exists and is writable ───────────
@@ -86,6 +87,32 @@ chmod u+rwx /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
 assert "prints Pre-flight reclaim message when subdir is non-writable" "printf '%s' \"${OUTPUT}\" | grep -q 'Pre-flight'"
 echo ""
 
+# ── Test 6: Exports TMPDIR/TMP/TEMP via GITHUB_ENV for subsequent steps ───────
+echo "Test 6: Exports tmp env vars via GITHUB_ENV"
+rm -rf /tmp/gh-aw
+GITHUB_ENV_FILE="$(mktemp)"
+set +e
+GITHUB_ENV="${GITHUB_ENV_FILE}" bash "${SCRIPT}" >/dev/null 2>&1
+EXIT_CODE=$?
+set -e
+assert "exits 0 when GITHUB_ENV is set" "[ '${EXIT_CODE}' -eq 0 ]"
+assert "creates /tmp/gh-aw/awf-tmp when GITHUB_ENV is set" "[ -d /tmp/gh-aw/awf-tmp ]"
+assert "exports TMPDIR" "grep -qx 'TMPDIR=/tmp/gh-aw/awf-tmp' '${GITHUB_ENV_FILE}'"
+assert "exports TMP" "grep -qx 'TMP=/tmp/gh-aw/awf-tmp' '${GITHUB_ENV_FILE}'"
+assert "exports TEMP" "grep -qx 'TEMP=/tmp/gh-aw/awf-tmp' '${GITHUB_ENV_FILE}'"
+rm -f "${GITHUB_ENV_FILE}"
+echo ""
+
+# ── Test 7: Succeeds when GITHUB_ENV is unset (local execution) ───────────────
+echo "Test 7: Succeeds when GITHUB_ENV is unset"
+rm -rf /tmp/gh-aw
+set +e
+env -u GITHUB_ENV bash "${SCRIPT}" >/dev/null 2>&1
+EXIT_CODE=$?
+set -e
+assert "exits 0 when GITHUB_ENV is unset" "[ '${EXIT_CODE}' -eq 0 ]"
+echo ""
+
 echo "Tests passed: ${TESTS_PASSED}"
 echo "Tests failed: ${TESTS_FAILED}"