Make the Box sandbox runtime optional. When ``box.enabled`` is false in
config (or when an enabled Box fails to connect), every dependent feature
degrades to the same disabled-state UX rather than crashing or silently
falling back to less safe code paths.
Backend:
- config.yaml: new top-level ``box.enabled: true`` flag (default true)
- BoxService:
- Read box.enabled on construction
- initialize() short-circuits when disabled — no remote WS connect, no
stdio subprocess fork
- _on_runtime_disconnect is a no-op when disabled (no reconnect loop
on a deliberately-off service)
- get_status() now exposes ``enabled`` so the frontend can tell
"disabled in config" from "configured but failed"
- MCP stdio loader (mcp_stdio.uses_box_stdio): requires box_service to
be available, not just installed
- MCP _init_stdio_python_server: when ap.box_service exists but is
unavailable, refuse the stdio server with an actionable error instead
of silently falling through to host-stdio (which bypasses the sandbox
the operator asked for). Setups without ap.box_service installed at
all keep the legacy host-stdio fallback for pre-Box dev mode
- SkillService._require_box_for_write: refuses create/update/install/
write_skill_file when ap.box_service is installed but unavailable.
Distinguishes disabled vs failed in the error message so the UI can
surface the right hint. Legacy setups (no ap.box_service) keep the
local fallback path — that distinction is what keeps the existing
local-skills tests valid
Tests:
- Box disabled-state behavior (4 cases)
- Skill write refusal in disabled & failed states (7 cases)
- MCP stdio runtime info policy updated to match new refuse-when-down
behavior
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Extract self-contained box runtime modules (actions, backend, client,
errors, models, runtime, security, server) to langbot-plugin-sdk and
update all imports to use `langbot_plugin.box.*`. Keep only service
and
connector in LangBot core as they depend on the Application context.
- Update docker-compose to use `langbot_plugin.box.server` entry
point
- Update pyproject.toml to use local SDK via `tool.uv.sources`
- Remove migrated source files and their unit/integration tests
- Update remaining test imports to match new module paths
## Summary
When Podman/Docker is available, all stdio-mode MCP servers now automatically
run inside Box containers with dependency installation, path rewriting, and
lifecycle management. When no container runtime exists, LangBot starts normally
and stdio MCP falls back to host-direct execution.
## What changed
### MCP stdio → Box integration (mcp.py)
- Add `MCPServerBoxConfig` pydantic model for structured box configuration
with validation and defaults (network, host_path_mode, timeouts, resources)
- Auto-infer `host_path` from command/args with venv detection: recognizes
`.venv/bin/python` patterns and walks up to the project root
- Rewrite host paths to container `/workspace` paths transparently
- Replace venv python commands with container-native `python`
- Auto-detect `pyproject.toml`/`setup.py`/`requirements.txt` and run
`pip install` inside the container before starting the MCP server
- Copy project to `/tmp` before install to handle read-only mounts
- Add retry with exponential backoff (3 retries, 2s/4s/8s delays)
- Add Box managed process health monitoring (poll every 5s)
- Fix session leak: `_cleanup_box_stdio_session()` now runs in `finally`
block of `_lifecycle_loop`, covering all exit paths
- Fix retry logic: `_ready_event` is only set after all retries exhaust
or on success, not on first failure
- Enhance `get_runtime_info_dict()` with `box_session_id` and `box_enabled`
### Box security (security.py — new)
- `validate_sandbox_security()` blocks dangerous host paths:
`/etc`, `/proc`, `/sys`, `/dev`, `/root`, `/boot`, `/run`,
docker.sock, podman socket
- Called at the start of `CLISandboxBackend.start_session()`
### Box models (models.py)
- Add `BoxHostMountMode.NONE` — skips volume mount entirely
- Adjust `validate_host_mount_consistency` to allow arbitrary workdir
when `host_path_mode=NONE`
### Box backend (backend.py)
- Add `validate_sandbox_security()` call in `start_session()`
- Add `langbot.box.config_hash` label on containers for drift detection
- Handle `BoxHostMountMode.NONE` — skip `-v` mount arg
- Add `cleanup_orphaned_containers()` to base class (no-op default) and
CLI implementation (single batched `rm -f` command)
### Box runtime (runtime.py)
- Call `cleanup_orphaned_containers()` during `initialize()` to remove
lingering containers from previous runs
### Box service (service.py)
- Graceful degradation: `initialize()` catches runtime errors and sets
`available=False` instead of crashing LangBot startup
- Add `available` property and guard on `execute_sandbox_tool()`
- Add `skip_host_mount_validation` parameter to `build_spec()` and
`create_session()` — MCP paths are admin-configured and trusted,
bypassing `allowed_host_mount_roots` restrictions meant for
LLM-generated sandbox_exec commands
### Default behavior
- stdio MCP servers automatically use Box when `box_service.available`
is True (Podman/Docker detected); no explicit `box` config needed
- When no container runtime exists, falls back to host-direct stdio
- MCP Box defaults: `network=on` (for pip install), `read_only_rootfs=false`
(for site-packages), `host_path_mode=ro`, `startup_timeout=120s`
### Tests
- `test_box_security.py`: blocked paths, safe paths, subpath rejection
- `test_mcp_box_integration.py`: config model, path rewriting, venv
unwrap, host_path inference, payload building, runtime info, box
availability check
- `test_box_service.py`: `BoxHostMountMode.NONE` validation tests
