diff --git a/CLAUDE.md b/CLAUDE.md
index a06d2ef..afacd23 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -48,9 +48,35 @@ Then ask fox what the mission is.
 
 - Python unit/integration: `tests.py` (571 tests)
 - C unit/integration/JIT/continuations/portal: `c/test.c` (83 tests)
-- Assembly unit/integration/functional: `asm/test.sh` (75 tests)
-- Shared functional: `tests/functional.lsp` (181 tests, runs in Python + C)
-- Total: 910 verified assertions via `make test-all`
+- Assembly unit/integration/functional: `asm/test.sh` (132 tests)
+- Shared functional: `tests/functional.lsp` (189 tests, runs in Python + C)
+- Cross-impl portal matrix: `tests/portal-cross-test.sh` (9 cells)
+- Portal benchmark: `tests/portal-benchmark.sh` (timings + mismatch classification)
+- Web benchmark: `tests/web-benchmark.sh` (all three impls + Python http.server + busybox)
+- Total: **975 verified assertions** via `make test-all`
+
+## Asm memory discipline — the heap does not shrink
+
+The asm implementation uses a bump allocator (r15). Every allocation
+(`string-append`, `tcp-recv`, `make-pair`, `number->string`, etc.)
+grows r15 monotonically. When r15 hits r13 (heap limit),
+`heap_grow` mmaps ANOTHER 64 MB chunk. **Nothing is ever freed.**
+
+A long-running asm server leaks ~64 MB every few thousand requests
+until it OOMs the machine. This actually crashed fox's machine on
+2026-04-16 — a benchmark server grew to 19.3 GB RSS / 30 GB virt.
+
+**Never leave an asm server running in the background.** Specifically:
+
+- Every background spawn in a bench script gets an EXIT trap:
+  `trap 'kill ${PIDS[@]} 2>/dev/null' EXIT`
+- For sustained-throughput benchmarks, bound iterations **inside the
+  .lsp** (e.g., `(if (> n 1000) (exit 0) (loop (+ n 1)))`) — never
+  rely on external kill signals alone.
+- Before declaring a session done, verify:
+  `ps -u fox -o pid,rss,cmd | grep uncommonlisp | grep -v grep` (no output = clean)
+- C has Boehm GC via `GC_MALLOC`. Python has Python's GC. Asm has
+  neither. Risk scales with how long the asm process lives.
 
 ## MOAD Scanner
 
diff --git a/examples/http-server.lsp b/examples/http-server.lsp
index 8c0aaac..eb160c2 100644
--- a/examples/http-server.lsp
+++ b/examples/http-server.lsp
@@ -15,6 +15,13 @@
 (define *crlf* "\r\n")
 (define *crlf-crlf* "\r\n\r\n")
 
+;;; Hard request ceiling. The asm impl has no GC: every request
+;;; bump-allocates heap cells that never get reclaimed. An unbounded
+;;; server leaks ~64 MB per heap growth until OOM. This ceiling makes
+;;; the server self-terminate long before it starves the machine.
+;;; Benchmarks that want a different cap should `set!` it after load.
+(define *max-requests* 50000)
+
 ;;; ── HTTP helpers ─────────────────────────────────────────────
 
 (define (http-response status ctype body)
@@ -77,14 +84,20 @@
 
 (define (serve)
   (let ((server (tcp-listen *port*)))
-    (display "uncommonlisp http server on :") (display *port*) (newline)
-    (let loop ()
-      (let ((client (tcp-accept server)))
-        (let ((req (tcp-recv client 4096)))
-          (if (and req (> (string-length req) 0))
-              (tcp-send client (handle-request req))
-              #f))
-        (tcp-close client))
-      (loop))))
+    (display "uncommonlisp http server on :") (display *port*)
+    (display " (max ") (display *max-requests*) (display " requests)") (newline)
+    (let loop ((n 0))
+      (if (>= n *max-requests*)
+          (begin
+            (display "request cap reached, exiting\n")
+            (tcp-close server))
+          (begin
+            (let ((client (tcp-accept server)))
+              (let ((req (tcp-recv client 4096)))
+                (if (and req (> (string-length req) 0))
+                    (tcp-send client (handle-request req))
+                    #f))
+              (tcp-close client))
+            (loop (+ n 1)))))))
 
 (serve)
diff --git a/tests/web-benchmark.sh b/tests/web-benchmark.sh
index 55f8a09..65920c7 100755
--- a/tests/web-benchmark.sh
+++ b/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 "═══════════════════════════════════════════════════════════════"