diff --git a/scripts/glasspane-stress-test.sh b/scripts/glasspane-stress-test.sh
new file mode 100755
index 0000000..879d4a4
--- /dev/null
+++ b/scripts/glasspane-stress-test.sh
@@ -0,0 +1,79 @@
+#!/bin/sh
+# Glasspane stress test — concurrent agent spawn + state tracking.
+# Requires: colibri-daemon running, python3.11, root (for nc to socket)
+set -eu
+
+SOCKET="${COLIBRI_SOCKET:-/var/run/colibri/colibri.sock}"
+PASS=0
+FAIL=0
+NC="mdo -u root nc -U $SOCKET -w 5"
+
+assert_pane_count() {
+    _desc="$1"; _expected="$2"
+    _json=$(printf '{"cmd":"glasspane-snapshot"}\n' | timeout 5 $NC 2>/dev/null | tail -1)
+    _count=$(echo "$_json" | python3.11 -c "import json,sys;print(len(json.load(sys.stdin)['data']['panes']))" 2>/dev/null || echo "0")
+    if [ "$_count" -ge "$_expected" ]; then
+        echo "  PASS: $_desc → $_count panes"
+        PASS=$((PASS + 1))
+    else
+        echo "  FAIL: $_desc (expected >= $_expected, got $_count)"
+        FAIL=$((FAIL + 1))
+    fi
+}
+
+assert_states_contain() {
+    _desc="$1"; shift
+    _json=$(printf '{"cmd":"glasspane-snapshot"}\n' | timeout 5 $NC 2>/dev/null | tail -1)
+    _states=$(echo "$_json" | python3.11 -c "import json,sys;d=json.load(sys.stdin)['data'];print(','.join(p['state'] for p in d['panes']))" 2>/dev/null || echo "ERROR")
+    for _exp in "$@"; do
+        case "$_states" in
+            *"$_exp"*)
+                echo "  PASS: $_desc → $_states"
+                PASS=$((PASS + 1))
+                return
+                ;;
+        esac
+    done
+    echo "  FAIL: $_desc (expected one of: $*, got $_states)"
+    FAIL=$((FAIL + 1))
+}
+
+echo "=== Glasspane Stress Test ==="
+echo "Socket: $SOCKET"
+echo ""
+
+# 1. Concurrent multi-spawn — spawn 3 smoke agents at once
+echo "--- Concurrent spawn (3 agents) ---"
+for _ in 1 2 3; do
+    printf '{"cmd":"spawn-agent","provider":"local","model":"/usr/local/bin/colibri-smoke-agent"}\n' | timeout 5 $NC >/dev/null 2>&1 &
+done
+wait
+sleep 2
+assert_pane_count "3 concurrent spawns" 3
+assert_states_contain "All agents done" "done"
+
+# 2. State transitions: working → done
+echo ""
+echo "--- State transitions ---"
+cat > /tmp/gst-working.sh << 'AGENT'
+#!/bin/sh
+echo '{"type":"turn_start"}'
+sleep 3
+echo '{"type":"turn_end"}'
+AGENT
+chmod +x /tmp/gst-working.sh
+
+timeout 5 sh -c "printf '{\"cmd\":\"spawn-agent\",\"provider\":\"local\",\"model\":\"/tmp/gst-working.sh\"}\n' | $NC" >/dev/null 2>&1 &
+SPAWN_PID=$!
+sleep 1
+assert_states_contain "Agent working mid-execution" "working"
+wait $SPAWN_PID 2>/dev/null || true
+sleep 3
+assert_states_contain "Agent finished → done" "done"
+rm -f /tmp/gst-working.sh
+
+echo ""
+echo "=== Results: $PASS passed, $FAIL failed ==="
+[ "$FAIL" -eq 0 ] && echo "✅ Glasspane state machine OK" && exit 0
+echo "❌ Glasspane test failures"
+exit 1