diff --git a/scripts/ci/deploy-site.sh b/scripts/ci/deploy-site.sh
index b83ff25..79bec6b 100755
--- a/scripts/ci/deploy-site.sh
+++ b/scripts/ci/deploy-site.sh
@@ -10,8 +10,20 @@ set -euo pipefail
 # shellcheck source=scripts/ci/lib-ssh.sh
 . scripts/ci/lib-ssh.sh
 
+# setup_ssh registers the EXIT cleanup trap itself (before writing the key),
+# so a mid-setup failure still cleans up — see lib-ssh.sh.
 setup_ssh
-trap teardown_ssh EXIT
+
+# Guard against deploying a missing/empty build: `rsync --delete` against an
+# empty source would wipe the live site.
+if [ ! -d web/website/dist ]; then
+  echo "==> deploy-site: web/website/dist/ does not exist — refusing to deploy" >&2
+  exit 1
+fi
+if ! find web/website/dist -mindepth 1 -print -quit | grep -q .; then
+  echo "==> deploy-site: web/website/dist/ is empty — refusing to deploy" >&2
+  exit 1
+fi
 
 DEPLOY_TARGET="root@${DEPLOY_HOST}:/var/www/pangolin-site/"
 echo "==> deploy-site: rsync web/website/dist/ -> ${DEPLOY_TARGET}"
diff --git a/scripts/ci/lib-ssh.sh b/scripts/ci/lib-ssh.sh
index e36ce72..fc7cb9f 100755
--- a/scripts/ci/lib-ssh.sh
+++ b/scripts/ci/lib-ssh.sh
@@ -3,10 +3,12 @@
 # (site / server). `source` this from deploy-*.sh.
 #
 # Provides:
-#   setup_ssh     -> writes $DEPLOY_SSH_KEY to a temp private key (mode 600),
-#                    registers the deploy host in known_hosts, and exports
-#                    SSH / RSYNC_SSH (ssh command strings) + SSH_KEY_FILE.
-#   teardown_ssh  -> removes the temp private key.
+#   setup_ssh     -> registers the EXIT cleanup trap first, then writes
+#                    $DEPLOY_SSH_KEY to a temp private key (mode 600),
+#                    registers the deploy host in a dedicated known_hosts
+#                    file, and exports SSH / RSYNC_SSH (ssh command strings)
+#                    + SSH_KEY_FILE.
+#   teardown_ssh  -> removes the temp private key + known_hosts file.
 #
 # Requires env: DEPLOY_SSH_KEY (PEM content of the deploy private key,
 # authorized for root on the target host).
@@ -21,9 +23,15 @@
 DEPLOY_HOST="${DEPLOY_HOST:-103.119.13.48}"
 DEPLOY_PORT="${DEPLOY_PORT:-22}"
 SSH_KEY_FILE="${SSH_KEY_FILE:-/tmp/pangolin_deploy_key.$$}"
+SSH_KNOWN_HOSTS_FILE="${SSH_KNOWN_HOSTS_FILE:-/tmp/pangolin_deploy_known_hosts.$$}"
 
 # setup_ssh — write the deploy key, register known_hosts, export SSH/RSYNC_SSH.
 setup_ssh() {
+  # Register cleanup FIRST: if anything below fails mid-setup (e.g. a
+  # transient ssh-keyscan error under `set -e`), the private key file must
+  # still be removed on exit rather than leaking.
+  trap teardown_ssh EXIT
+
   if [ -z "${DEPLOY_SSH_KEY:-}" ]; then
     echo "==> setup_ssh: DEPLOY_SSH_KEY is empty" >&2
     return 1
@@ -32,22 +40,30 @@ setup_ssh() {
   mkdir -p ~/.ssh
   chmod 700 ~/.ssh
 
+  # Pre-create the key file with restrictive perms *before* writing any key
+  # material into it, so there is no window at the default umask between
+  # file creation and chmod.
+  install -m 600 /dev/null "${SSH_KEY_FILE}"
+
   # `printf '%s\n'` 末尾补一个换行：Forgejo/Gitea 存 secret 会去掉结尾换行,
   # 而缺结尾换行的 OpenSSH 格式私钥会被判为 "invalid format" 拒绝加载,
   # 退化成无密钥 → Permission denied。多补的换行对已含结尾换行的 PEM 无害。
   printf '%s\n' "${DEPLOY_SSH_KEY}" > "${SSH_KEY_FILE}"
-  chmod 600 "${SSH_KEY_FILE}"
 
-  ssh-keyscan -p "${DEPLOY_PORT}" -H "${DEPLOY_HOST}" >> ~/.ssh/known_hosts 2>/dev/null
+  # Populate a dedicated known_hosts file via TOFU keyscan. This is
+  # belt-and-suspenders: `accept-new` below will pin the host key on first
+  # real connection regardless, so a transient keyscan failure must not
+  # abort the deploy.
+  ssh-keyscan -p "${DEPLOY_PORT}" -H "${DEPLOY_HOST}" >> "${SSH_KNOWN_HOSTS_FILE}" 2>/dev/null || true
 
-  SSH="ssh -i ${SSH_KEY_FILE} -p ${DEPLOY_PORT} -o StrictHostKeyChecking=no"
-  RSYNC_SSH="ssh -i ${SSH_KEY_FILE} -p ${DEPLOY_PORT} -o StrictHostKeyChecking=no"
-  export SSH RSYNC_SSH SSH_KEY_FILE DEPLOY_HOST DEPLOY_PORT
-  echo "==> setup_ssh: key written to ${SSH_KEY_FILE}, known_hosts updated for ${DEPLOY_HOST}:${DEPLOY_PORT}"
+  SSH="ssh -i ${SSH_KEY_FILE} -p ${DEPLOY_PORT} -o StrictHostKeyChecking=accept-new -o UserKnownHostsFile=${SSH_KNOWN_HOSTS_FILE}"
+  RSYNC_SSH="ssh -i ${SSH_KEY_FILE} -p ${DEPLOY_PORT} -o StrictHostKeyChecking=accept-new -o UserKnownHostsFile=${SSH_KNOWN_HOSTS_FILE}"
+  export SSH RSYNC_SSH SSH_KEY_FILE SSH_KNOWN_HOSTS_FILE DEPLOY_HOST DEPLOY_PORT
+  echo "==> setup_ssh: key written to ${SSH_KEY_FILE}, known_hosts pinned (accept-new) for ${DEPLOY_HOST}:${DEPLOY_PORT}"
 }
 
-# teardown_ssh — remove the temp private key.
+# teardown_ssh — remove the temp private key + known_hosts file.
 teardown_ssh() {
-  rm -f "${SSH_KEY_FILE}"
+  rm -f "${SSH_KEY_FILE}" "${SSH_KNOWN_HOSTS_FILE}"
   echo "==> teardown_ssh: removed ${SSH_KEY_FILE}"
 }