mesa-core 1.2.1

Reference implementation of the MESA specification: a semantic safety and coordination layer for AI-operated smart environments.

mesa-core

mesa-core decides whether an AI agent should be allowed to act on a smart-home device, and how cautious it should be about it.

When an assistant tries to turn on a light, unlock the front door, or change the thermostat, mesa-core answers three questions: is this allowed, should the user confirm it first, and why. It ships with safe defaults (a light is fine to control automatically; unlike a lock) that you refine for each home.

It is the reference implementation of the MESA specification. It has no runtime dependencies and never talks to Home Assistant directly: you hand it device state through callback functions, and it hands you decisions.

pip install mesa-core

Quick look

from mesa_core import MesaEnforcer, ProfileStore
from mesa_core.backends import MemoryBackend

enforcer = MesaEnforcer(ProfileStore(backend=MemoryBackend()))

# An AI agent wants to unlock the front door. Should it?
result = enforcer.evaluate("lock.front_door", "lock.unlock")

result.allowed   # False
result.reason    # "Entity is prohibited by policy: lock.front_door"

How decisions work

• Every device has a control mode: act freely, ask the user first, read-only, or never act.
• Devices you have not configured fall back to safe defaults: lights act freely, locks and alarm panels are off-limits, everything else asks first.
• Rules can be set for a single device, an area, or a whole device type, and are combined with a bias toward caution: the more restrictive rule wins, and anything that cannot be checked blocks rather than allows.
• You can add finer limits (cap the speaker volume after 10pm) and time-based rules (no blinds before sunrise).

Asking the user to confirm

When a device is set to confirm first, evaluate returns a challenge instead of a yes. Show the action to the user, then call again with the token from the approved challenge.

result = enforcer.evaluate("cover.garage", "cover.open_cover")
if result.confirmation_challenge:
    # present result.confirmation_challenge to the user; once approved,
    # build a confirmation_token from it and re-submit the same call:
    result = enforcer.evaluate(
        "cover.garage", "cover.open_cover",
        confirmation_token=approved_token,
    )

Reading a device's profile

ProfileStore resolves the effective profile after inheritance and defaults. Use a file backend to persist profiles under your HA config:

from mesa_core import ProfileStore
from mesa_core.backends import JsonFileBackend

store = ProfileStore(backend=JsonFileBackend("/config/mesa/"))
profile = store.get_effective("light.living_room_ceiling")
profile.operational_boundaries.control_mode   # ControlMode.AUTONOMOUS

Exposing it to an AI agent (MCP)

Register MESA's tools into an MCP server so the agent can look up profiles and caller context for itself.

from mesa_core.mcp import register_mesa_tools

register_mesa_tools(store, adapter="fastmcp", server=app)

Adapters ship for FastMCP and the MCP Python SDK (pip install "mesa-core[fastmcp]" or "mesa-core[mcp]"). Any other framework can implement a small registration protocol.

Passing lease_manager=LeaseManager(store) also registers the advisory coordination tools (mesa_request_lease, mesa_release_lease), which let cooperating agents signal short-lived intent to each other. They are signals, not locks; see Enrichment Section 21 before relying on them.

With a get_semantic_moments callback, mesa_get_profile can also surface the purpose-specific triggers and conditions an entity participates in (Home Assistant 2026.7+), live from HA, for agent context only.

Loading profiles shipped by integrations

An HA integration can ship a mesa_profile.json describing its own devices. Load it with:

from mesa_core import import_from_integration

profile = import_from_integration("/config/custom_components/my_integration")
if profile is not None:
    store.set_integration_profile(profile.entity_id, profile)

Documentation

• MESA Overview - the problem MESA solves, in plain terms
• Getting Started - write your first profile
• Specification - the full normative reference
• Enrichment - optional advanced domains
• Module Proposal - how this library is built

Status

mesa-core v1.2.1 is ready for use: profile storage and inheritance, enforcement with confirmation, temporal constraints including solar conditions, the MCP retrieval tools, privacy controls, the advisory lease protocol, and portable profile export/import are all implemented. Multi-agent lease preemption is planned for v2.

git clone https://github.com/sfox38/mesa-core
cd mesa-core
pip install -e ".[dev]"
pytest tests/ -v       # test suite
ruff check . && mypy   # lint and type check