diff --git a/tools/benchmark-watch-install.sh b/tools/benchmark-watch-install.sh
index 1e5f30f..d4c2136 100755
--- a/tools/benchmark-watch-install.sh
+++ b/tools/benchmark-watch-install.sh
@@ -27,7 +27,11 @@
 # Measured on the Xiaomi phone (Android 12, MIUI 14): an adb-started install raises the dialog after
 # about 1.7 s with a ten second deny countdown, so there is time for one dump and one tap; the same
 # dialog is FLAG_SECURE, so a screencap of it shows whatever is behind it.
-set -euo pipefail
+# No `-e`: this is a watcher that has to survive for the whole run, and a single failed adb call must not
+# end it. It ended silently once before, in the middle of a benchmark run, which is why it looked like it
+# had "stopped running" — a helper ending in `| head -1` takes a SIGPIPE when `head` exits first, and
+# `pipefail` plus `-e` turned that into an exit.
+set -uo pipefail
 
 seconds=600
 interval=2
@@ -83,7 +87,7 @@ is_installer() {
 
 # The window token, so the same dialog is not answered twice while it closes.
 window_token() {
-    sed -n 's/.*mCurrentFocus=Window{\([0-9a-f]*\).*/\1/p' <<<"$1" | head -1
+    sed -n 's/.*mCurrentFocus=Window{\([0-9a-f]*\).*/\1/p' <<<"$1" | head -1 || true
 }
 
 # The activity that owns the focused window. Dialogs each get their own window token, so the token
@@ -91,7 +95,7 @@ window_token() {
 # which is exactly what happens when a run installs twice in quick succession. The activity name is
 # stable across both, and it is still specific enough that a tap can only ever land on an installer.
 installer_activity() {
-    sed -n 's/.*u0 \([^ }]*\).*/\1/p' <<<"$1" | head -1
+    sed -n 's/.*u0 \([^ }]*\).*/\1/p' <<<"$1" | head -1 || true
 }
 
 # Prints "<x> <y> <label>" for the dialog's Install button, or nothing at all.
@@ -201,9 +205,16 @@ answer_dialog() {
 
 deadline=$((SECONDS + seconds))
 burst_until=0
+last_beat=$SECONDS
 echo "benchmark-watch-install: watching for $seconds s (idle poll ${interval}s, burst after a dialog)"
 
 while [ $SECONDS -lt $deadline ]; do
+    # A heartbeat, so "is it still running?" can be answered by reading the log instead of guessing.
+    if [ $((SECONDS - last_beat)) -ge 30 ]; then
+        echo "  $(date +%H:%M:%S) still watching: $taps answered, $opened_windows window(s) seen"
+        last_beat=$SECONDS
+    fi
+
     focus=$(focused_window)
     if is_installer "$focus"; then
         answer_dialog "$focus"