feat(docker): add host command bridge

docker/Dockerfile

@@ -1,6 +1,9 @@
 # syntax=docker/dockerfile:1.7
 
 ARG NODE_VERSION=22-bookworm-slim
+ARG DOCKER_CLI_VERSION=29-cli
+
+FROM docker:${DOCKER_CLI_VERSION} AS docker-cli
 
 FROM node:${NODE_VERSION} AS package
 
@@ -32,6 +35,7 @@ ENV NODE_ENV=production \
   PI_WEB_DATA_DIR=/data/pi-web \
   PI_WEB_SESSIOND_SOCKET=/data/pi-web/sessiond.sock \
   PI_CODING_AGENT_DIR=/data/pi-agent \
+  HOSTEXEC_IMAGE=alpine:3.22 \
   SHELL=/bin/bash \
   TERM=xterm-256color
 
@@ -50,6 +54,8 @@ RUN apt-get update \
 
 COPY --from=package /usr/local/lib/node_modules /usr/local/lib/node_modules
 COPY --from=package /usr/local/bin /usr/local/bin
+COPY --from=docker-cli /usr/local/bin/docker /usr/local/bin/docker
+COPY --chmod=0755 bin/hostexec /usr/local/bin/hostexec
 
 WORKDIR /workspace
 USER node

docker/bin/hostexec

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+usage() {
+  cat >&2 <<'EOF'
+Usage: hostexec <command...>
+
+Run a command on the Docker host by starting a temporary privileged helper
+container through the mounted Docker socket and entering the host namespaces.
+EOF
+}
+
+if [ "$#" -eq 0 ]; then
+  usage
+  exit 64
+fi
+
+if ! command -v docker >/dev/null 2>&1; then
+  echo "hostexec: docker CLI not found in this container" >&2
+  exit 127
+fi
+
+docker_host="${DOCKER_HOST:-unix:///var/run/docker.sock}"
+if [[ "$docker_host" == unix://* ]]; then
+  socket_path="${docker_host#unix://}"
+  if [ ! -S "$socket_path" ]; then
+    echo "hostexec: Docker socket is not accessible as a Unix socket at $socket_path" >&2
+    exit 69
+  fi
+fi
+
+helper_image="${HOSTEXEC_IMAGE:-alpine:3.22}"
+tty_args=(--interactive)
+if [ -t 0 ] && [ -t 1 ]; then
+  tty_args+=(--tty)
+fi
+
+exec docker run \
+  --rm \
+  "${tty_args[@]}" \
+  --pull=missing \
+  --privileged \
+  --security-opt label=disable \
+  --pid=host \
+  --network=host \
+  --volume /:/host:rw \
+  "$helper_image" \
+  nsenter -t 1 -m -u -i -n -p -- "$@"

docker/compose.yml

@@ -14,6 +14,7 @@ x-pi-web-environment: &pi-web-environment
   PI_WEB_DATA_DIR: /data/pi-web
   PI_WEB_SESSIOND_SOCKET: /data/pi-web/sessiond.sock
   PI_CODING_AGENT_DIR: /data/pi-agent
+  HOSTEXEC_IMAGE: ${HOSTEXEC_IMAGE:-alpine:3.22}
   PI_WEB_MAX_UPLOAD_BYTES: ${PI_WEB_MAX_UPLOAD_BYTES:-67108864}
 
 x-pi-web-volumes: &pi-web-volumes
@@ -46,6 +47,8 @@ services:
     user: "${PI_WEB_UID:-1000}:${PI_WEB_GID:-1000}"
     group_add:
       - "${DOCKER_GID:-0}"
+    security_opt:
+      - label=disable
     environment: *pi-web-environment
     volumes: *pi-web-volumes
     healthcheck:
@@ -66,6 +69,8 @@ services:
     user: "${PI_WEB_UID:-1000}:${PI_WEB_GID:-1000}"
     group_add:
       - "${DOCKER_GID:-0}"
+    security_opt:
+      - label=disable
     environment:
       <<: *pi-web-environment
       PI_WEB_HOST: 0.0.0.0