bench: fd-scan tool; BRINGUP session record - dry drills, homing witness, panic drill

scripts/bench/fdscan.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+# Runs ON the board. While forgectrl spawns helper children (the update
+# check's curl, the snapshot's media-ctl/v4l2-ctl), scan every child for a
+# descriptor on the pulse device. Expected: none - only the controller
+# inherits /dev/glowforge (F_SETFD cleared for that one spawn); every other
+# child gets the O_CLOEXEC default. Usage: fdscan.sh <panel-token>
+TOK="$1"
+P=$(pidof forgectrl)
+[ -n "$P" ] || { echo "forgectrl not running"; exit 1; }
+CTRL=$(pidof grblHAL_glowforge)
+echo "forgectrl pid $P, controller pid ${CTRL:-none}"
+# Kick the helpers off in the background.
+( curl -s -X POST -H "X-ForgeFIRM-Token: $TOK" http://127.0.0.1:8080/update/check >/tmp/upd.out 2>&1 ) &
+( curl -s -o /tmp/snap.jpg http://127.0.0.1:8080/cam/snapshot ) &
+hits=0; seen=0; names=""
+i=0
+while [ $i -lt 60 ]; do          # ~6 s of scanning at 10 Hz
+  for c in $(pgrep -P "$P"); do
+    seen=$((seen+1))
+    n=$(cat /proc/$c/comm 2>/dev/null)
+    names="$names $n"
+    if ls -l /proc/$c/fd 2>/dev/null | grep -q glowforge; then
+      if [ "$c" != "$CTRL" ]; then hits=$((hits+1)); echo "HIT: child $c ($n) holds the pulse device"; ls -l /proc/$c/fd | grep glowforge; fi
+    fi
+  done
+  i=$((i+1)); usleep 100000 2>/dev/null || sleep 0.1
+done
+wait
+echo "children observed: $(echo $names | tr ' ' '\n' | sort | uniq -c | tr '\n' ';')"
+echo "controller holds pulse fd: $(ls -l /proc/$CTRL/fd 2>/dev/null | grep -c glowforge)"
+echo "update/check reply: $(cat /tmp/upd.out | head -c 200)"
+echo "snapshot bytes: $(wc -c < /tmp/snap.jpg 2>/dev/null)"
+echo "non-controller children holding the pulse device: $hits  ($([ $hits -eq 0 ] && echo PASS || echo FAIL))"