diff --git a/install.sh b/install.sh
index f81ac7f45..24b139420 100755
--- a/install.sh
+++ b/install.sh
@@ -66,6 +66,82 @@ else
   C_GREEN='' C_BOLD='' C_DIM='' C_RED='' C_YELLOW='' C_CYAN='' C_RESET=''
 fi
 
+# ---------------------------------------------------------------------------
+# Cleanup — kill backgrounded processes and remove temp files on exit/signal.
+# ---------------------------------------------------------------------------
+_cleanup_pids=()
+_cleanup_files=()
+
+remove_tracked_pid() {
+  local target="$1"
+  local kept=()
+  local value
+  if (( ${#_cleanup_pids[@]} == 0 )); then
+    return
+  fi
+  for value in "${_cleanup_pids[@]}"; do
+    if [[ "$value" != "$target" ]]; then
+      kept+=("$value")
+    fi
+  done
+  if (( ${#kept[@]} )); then
+    _cleanup_pids=("${kept[@]}")
+  else
+    _cleanup_pids=()
+  fi
+}
+
+remove_tracked_file() {
+  local target="$1"
+  local kept=()
+  local value
+  if (( ${#_cleanup_files[@]} == 0 )); then
+    return
+  fi
+  for value in "${_cleanup_files[@]}"; do
+    if [[ "$value" != "$target" ]]; then
+      kept+=("$value")
+    fi
+  done
+  if (( ${#kept[@]} )); then
+    _cleanup_files=("${kept[@]}")
+  else
+    _cleanup_files=()
+  fi
+}
+
+cleanup() {
+  local rc=$?
+  set +e
+  if (( ${#_cleanup_pids[@]} )); then
+    for pid in "${_cleanup_pids[@]}"; do
+      kill "$pid" 2>/dev/null || true
+    done
+  fi
+  if (( ${#_cleanup_files[@]} )); then
+    for f in "${_cleanup_files[@]}"; do
+      rm -rf "$f"
+    done
+  fi
+  return "$rc"
+}
+
+# Handle signals by running cleanup and then re-raising so the parent sees
+# the correct signal exit status instead of silently continuing.
+trap_signal() {
+  local sig="$1"
+  cleanup
+  trap - "$sig"
+  kill -s "$sig" "$$"
+}
+
+register_cleanup_traps() {
+  trap cleanup EXIT
+  trap 'trap_signal INT' INT
+  trap 'trap_signal TERM' TERM
+  trap 'trap_signal HUP' HUP
+}
+
 # ---------------------------------------------------------------------------
 # Helpers
 # ---------------------------------------------------------------------------
@@ -206,8 +282,10 @@ spin() {
 
   local log
   log=$(mktemp)
+  _cleanup_files+=("$log")
   "$@" >"$log" 2>&1 &
   local pid=$! i=0
+  _cleanup_pids+=("$pid")
   local frames=('⠋' '⠙' '⠹' '⠸' '⠼' '⠴' '⠦' '⠧' '⠇' '⠏')
 
   while kill -0 "$pid" 2>/dev/null; do
@@ -228,6 +306,9 @@ spin() {
     printf "\n"
   fi
   rm -f "$log"
+  # Untrack resources so cleanup() does not act on stale/recycled entries.
+  remove_tracked_pid "$pid"
+  remove_tracked_file "$log"
   return $status
 }
 
@@ -372,9 +453,11 @@ install_nodejs() {
   local NVM_SHA256="4b7412c49960c7d31e8df72da90c1fb5b8cccb419ac99537b737028d497aba4f"
   local nvm_tmp
   nvm_tmp="$(mktemp)"
+  _cleanup_files+=("$nvm_tmp")
   curl -fsSL "https://raw.githubusercontent.com/nvm-sh/nvm/${NVM_VERSION}/install.sh" -o "$nvm_tmp" \
     || {
       rm -f "$nvm_tmp"
+      remove_tracked_file "$nvm_tmp"
       error "Failed to download nvm installer"
     }
   local actual_hash
@@ -388,11 +471,13 @@ install_nodejs() {
   fi
   if [[ "$actual_hash" != "$NVM_SHA256" ]]; then
     rm -f "$nvm_tmp"
+    remove_tracked_file "$nvm_tmp"
     error "nvm installer integrity check failed\n  Expected: $NVM_SHA256\n  Actual:   $actual_hash"
   fi
   info "nvm installer integrity verified"
   spin "Installing nvm..." bash "$nvm_tmp"
   rm -f "$nvm_tmp"
+  remove_tracked_file "$nvm_tmp"
   ensure_nvm_loaded
   spin "Installing Node.js 22..." bash -c ". \"$NVM_DIR/nvm.sh\" && nvm install 22 --no-progress"
   ensure_nvm_loaded
@@ -494,6 +579,10 @@ pre_extract_openclaw() {
   info "Pre-extracting openclaw@${openclaw_version} with system tar (GH-503 workaround)…"
   local tmpdir
   tmpdir="$(mktemp -d)"
+  trap 'rm -rf "$tmpdir"' EXIT INT TERM HUP
+  # Not tracked in _cleanup_files: this function runs in a child shell via
+  # spin()/bash -c, so array mutations do not reach the parent.  The child
+  # cleans up tmpdir itself; on interrupt, spin() kills the child PID.
   if npm pack "openclaw@${openclaw_version}" --pack-destination "$tmpdir" >/dev/null 2>&1; then
     local tgz
     tgz="$(find "$tmpdir" -maxdepth 1 -name 'openclaw-*.tgz' -print -quit)"
@@ -666,6 +755,7 @@ post_install_message() {
 # Main
 # ---------------------------------------------------------------------------
 main() {
+  register_cleanup_traps
   # Parse flags
   NON_INTERACTIVE=""
   for arg in "$@"; do
diff --git a/test/install-preflight.test.js b/test/install-preflight.test.js
index e24fe17e4..bbd39b124 100644
--- a/test/install-preflight.test.js
+++ b/test/install-preflight.test.js
@@ -1101,6 +1101,25 @@ describe("installer pure helpers", () => {
     );
   }
 
+  it("does not install cleanup traps when sourced", () => {
+    const r = spawnSync(
+      "bash",
+      [
+        "-c",
+        `source "${INSTALLER}" 2>/dev/null; [[ -z "$(trap -p EXIT)" && -z "$(trap -p INT)" && -z "$(trap -p TERM)" && -z "$(trap -p HUP)" ]] && echo clean`,
+      ],
+      {
+        cwd: path.join(import.meta.dirname, ".."),
+        encoding: "utf-8",
+        env: {
+          HOME: os.tmpdir(),
+          PATH: TEST_SYSTEM_PATH,
+        },
+      },
+    );
+    expect(r.stdout.trim()).toBe("clean");
+  });
+
   // -- version_gte --
 
   it("version_gte: equal versions return 0", () => {