guardrails: bound http server, trap+cleanup bench, asm-no-GC in CLAUDE.md

Prevent recurrence of 2026-04-16 incident where a leaked asm HTTP
server grew to 19.3 GB RSS and crashed the machine.

examples/http-server.lsp:
- Adds *max-requests* = 50000 hard ceiling. Server self-terminates
  before unbounded heap growth reaches dangerous levels.
- Loop tracks request count, exits cleanly + closes server socket.

tests/web-benchmark.sh:
- SPAWNED_PIDS array tracks every background process.
- EXIT/INT/TERM trap kills them all (SIGTERM then SIGKILL).
- stop_server does SIGTERM with 500ms grace period then SIGKILL.
- Final straggler check via pgrep narrows to actual HTTP server
  processes (not shell/tmux with "uncommonlisp" in the name).
- pkill -9 fallback as belt-and-suspenders.

CLAUDE.md:
- New "Asm memory discipline" section documents the bump allocator
  leak behavior and the required operational discipline.
- Test counts updated (571 py + 83 c + 132 asm + 189 shared = 975).

tests/web-benchmark.sh

@@ -16,6 +16,35 @@ PY="python3 uncommonlisp.py --fast"
 C="./c/uncommonlisp"
 ASM="./asm/uncommonlisp"
 
+# Track every server PID we spawn; the EXIT trap kills them all.
+# Asm has no GC — a leaked server leaks 64 MB per heap growth
+# indefinitely. Belt + suspenders: kill the whole process group too.
+declare -a SPAWNED_PIDS=()
+
+cleanup() {
+    local pid
+    for pid in "${SPAWNED_PIDS[@]}"; do
+        kill "$pid" 2>/dev/null
+    done
+    sleep 0.2
+    for pid in "${SPAWNED_PIDS[@]}"; do
+        kill -9 "$pid" 2>/dev/null
+    done
+    rm -rf "${STATIC_DIR:-/nonexistent/xyz}"
+    # Final sanity: any stray servers from examples/http-server?
+    # Narrow to processes actually serving the HTTP example, not the
+    # shell running this script or tmux sessions with "uncommonlisp"
+    # in their name.
+    local strays
+    strays=$(pgrep -u "$USER" -f 'examples/http-server\.lsp|http\.server 8080' | wc -l)
+    if [ "$strays" -gt 0 ]; then
+        echo "WARNING: $strays HTTP server process(es) still running:" >&2
+        pgrep -u "$USER" -af 'examples/http-server\.lsp|http\.server 8080' >&2
+        pkill -9 -u "$USER" -f 'examples/http-server\.lsp|http\.server 8080' 2>/dev/null
+    fi
+}
+trap cleanup EXIT INT TERM
+
 pad() { printf "  %-36s " "$1"; }
 
 bench_one() {
@@ -38,18 +67,19 @@ print(f'{rps:8.0f} req/s   ({t:.3f}s total, concurrency $CONCURRENCY)')"
 # Setup a 1KB static file for file-serving benchmarks
 STATIC_DIR=$(mktemp -d)
 printf '%.0s0123456789abcdef0123456789abcdef' {1..32} > "$STATIC_DIR/bench"
-trap "rm -rf $STATIC_DIR" EXIT
 
 echo "═══════════════════════════════════════════════════════════════"
 echo "HTTP benchmark — $REQUESTS requests, concurrency $CONCURRENCY"
 echo "═══════════════════════════════════════════════════════════════"
 echo
 
-# Helper to start + wait for port ready
+# Helper to start + wait for port ready. Adds pid to SPAWNED_PIDS so
+# the EXIT trap kills it even if the script dies unexpectedly.
 start_server() {
     local cmd="$1" port="$2"
     eval "$cmd" > /dev/null 2>&1 &
     local pid=$!
+    SPAWNED_PIDS+=("$pid")
     for _ in $(seq 1 20); do
         if curl -s -o /dev/null -w "%{http_code}" "http://localhost:$port/" 2>/dev/null | grep -q 200; then
             echo "$pid"
@@ -61,38 +91,50 @@ start_server() {
     return 1
 }
 
+stop_server() {
+    local pid="$1"
+    # SIGTERM first; if the process is blocked in accept() it may not
+    # exit cleanly, so force-kill after a short grace period.
+    kill "$pid" 2>/dev/null
+    for _ in 1 2 3 4 5; do
+        kill -0 "$pid" 2>/dev/null || break
+        sleep 0.1
+    done
+    kill -9 "$pid" 2>/dev/null
+    wait "$pid" 2>/dev/null
+    sleep 0.2
+}
+
 # ── uncommonlisp Python ──
 PID=$(start_server "$PY examples/http-server.lsp" 8080)
 bench_one "uncommonlisp Python  (/bench, 1 KB)" 8080 /bench
-kill "$PID" 2>/dev/null; wait "$PID" 2>/dev/null
-sleep 0.3
+stop_server "$PID"
 
 # ── uncommonlisp C ──
 PID=$(start_server "$C examples/http-server.lsp" 8080)
 bench_one "uncommonlisp C       (/bench, 1 KB)" 8080 /bench
-kill "$PID" 2>/dev/null; wait "$PID" 2>/dev/null
-sleep 0.3
+stop_server "$PID"
 
 # ── uncommonlisp asm ──
 PID=$(start_server "$ASM < examples/http-server.lsp" 8080)
 bench_one "uncommonlisp asm     (/bench, 1 KB)" 8080 /bench
-kill "$PID" 2>/dev/null; wait "$PID" 2>/dev/null
-sleep 0.3
+stop_server "$PID"
 
 # ── Python http.server (stdlib) ──
 (cd "$STATIC_DIR" && python3 -m http.server 8080 > /dev/null 2>&1) &
 PID=$!
+SPAWNED_PIDS+=("$PID")
 sleep 1
 bench_one "python3 -m http.server (1 KB file)" 8080 /bench
-kill "$PID" 2>/dev/null; wait "$PID" 2>/dev/null
-sleep 0.3
+stop_server "$PID"
 
 # ── busybox httpd ──
 busybox httpd -f -p 127.0.0.1:8080 -h "$STATIC_DIR" > /dev/null 2>&1 &
 PID=$!
+SPAWNED_PIDS+=("$PID")
 sleep 0.5
 bench_one "busybox httpd         (1 KB file)" 8080 /bench
-kill "$PID" 2>/dev/null; wait "$PID" 2>/dev/null
+stop_server "$PID"
 
 echo
 echo "═══════════════════════════════════════════════════════════════"