diff --git a/scripts/wait_readyz.sh b/scripts/wait_readyz.sh
index adcf49e..85a827f 100755
--- a/scripts/wait_readyz.sh
+++ b/scripts/wait_readyz.sh
@@ -16,6 +16,9 @@ while (( SECONDS < deadline )); do
     if [[ "$status" == "ready" ]]; then
       elapsed=$((SECONDS - start))
       echo "readyz: status=ready in ${elapsed}s"
+      # Timing lands in /tmp by default, which suits CI and Docker. Set
+      # STATEWAVE_COLD_TIMING_FILE to write elsewhere — e.g. where /tmp is
+      # missing or read-only, or to keep the value as a build artifact.
       printf '%s\n' "$elapsed" > "${STATEWAVE_COLD_TIMING_FILE:-/tmp/statewave_cold_ready_seconds}"
       exit 0
     fi