mcp-hs4

Production-oriented MCP server for HomeSeer HS4.

This project provides MCP tools, resources, and prompts so MCP-compatible LLM agents can read and control HS4 safely with auditability, guarded writes, and local-sidecar deployment.

Start Here

1. Install and build:

npm install
npm run build

2. Configure environment:

cp .env.example .env
# set HS4_BASE_URL and any auth/guard settings needed for your installation

3. Run server (production path):

node dist/index.js

4. Optional development mode:

npm run dev

5. Register in Codex CLI:

codex mcp add hs4 \
  --env HS4_BASE_URL=http://127.0.0.1 \
  --env HS4_REQUIRE_CONFIRM=true \
  --env HS4_SAFE_MODE=read_write \
  --env MCP_LOG_LEVEL=info \
  -- node /absolute/path/to/mcp-hs4/dist/index.js

6. Smoke test:

codex mcp list
codex mcp get hs4 --json
codex exec --skip-git-repo-check -C /absolute/path/to/mcp-hs4 \
  "Use only hs4 MCP tools. Run hs4.selftest.run and summarize any warnings."

Related MCP server: hass-mcp-server

At a Glance

• Contract namespaces: hs4.*, hs4.admin.*

• Runtime: Node 20+, TypeScript

• Transports: stdio (default), http (streamable MCP endpoint)

• Safety defaults: confirm+intent+reason guardrails, dry-run-first intent tools, audit logging

• Write reliability: post-write verification with fallback logic in hs4.devices.set

Architecture

MCP Client (Codex / Claude / Cursor / Cline)
  -> MCP transport (stdio or HTTP)
mcp-hs4 server
  -> HS4 JSON API (/JSON?request=...)
  -> HS4 script route (/runscript.html)
HomeSeer HS4

Project Scope

• This repository is strictly the HomeSeer 4 MCP server implementation (mcp-hs4).

• Client-specific adapters, UIs, and app integrations belong in separate repositories.

• Public API contract in this repo is hs4.* and hs4.admin.*.

Current Status

• Runtime: TypeScript/Node 20+

• MCP SDK: @modelcontextprotocol/sdk

• HS4 integration target: JSON API (/JSON?request=...) plus script command path (/runscript.html)

• Contract version: 1.0.0

• Deployment profiles: stdio for local MCP client process spawning (default), streamable-http for optional local LAN service mode

Implemented MCP Surface

Namespaces

• hs4.* standard read and control operations

• hs4.admin.* privileged administration operations (disabled by default)

Tools

Registered tools are listed below. For release verification, confirm the runtime contract with hs4://capabilities/matrix.

Core tools:

• hs4.health.get

• hs4.help.route

• hs4.resolve.devices

• hs4.resolve.events

• hs4.resolve.cameras

• hs4.change.prepare

• hs4.change.commit

• hs4.intent.device_set_by_name

• hs4.intent.event_run_by_name

• hs4.intent.scene_activate

• hs4.selftest.run

• hs4.devices.list

• hs4.devices.get

• hs4.devices.controls.get

• hs4.devices.status.get

• hs4.devices.set

• hs4.events.list

• hs4.events.get

• hs4.events.definition.get

• hs4.events.run

• hs4.scripts.run

• hs4.plugins.function.call

• hs4.plugins.list

• hs4.cameras.list

• hs4.cameras.snapshot.get

• hs4.cameras.pan

• hs4.audit.query

Admin tools:

• hs4.admin.users.list

• hs4.admin.users.create

• hs4.admin.users.update

• hs4.admin.users.delete

• hs4.admin.users.set_role

• hs4.admin.plugins.catalog.get

• hs4.admin.plugins.install

• hs4.admin.plugins.update

• hs4.admin.plugins.remove

• hs4.admin.plugins.set_enabled

• hs4.admin.plugins.restart

• hs4.admin.interfaces.list

• hs4.admin.interfaces.add

• hs4.admin.interfaces.update

• hs4.admin.interfaces.remove

• hs4.admin.interfaces.restart

• hs4.admin.interfaces.diagnostics

• hs4.admin.system.backup.start

• hs4.admin.system.restore.start

• hs4.admin.system.service.restart

• hs4.admin.system.shutdown

• hs4.admin.system.config.get

• hs4.admin.system.config.set

• hs4.admin.cameras.config.list

• hs4.admin.cameras.config.create

• hs4.admin.cameras.config.update

• hs4.admin.cameras.config.delete

• hs4.admin.cameras.stream_profile.set

• hs4.admin.cameras.recording.set

• hs4.admin.events.create

• hs4.admin.events.update

• hs4.admin.events.delete

• hs4.admin.config.device_metadata.set

• hs4.admin.config.categories.list

• hs4.admin.config.category.upsert

• hs4.admin.config.category.delete

Resources

• hs4://devices/catalog

• hs4://devices/catalog/full

• hs4://devices/status

• hs4://devices/status/full

• hs4://events/catalog

• hs4://capabilities/matrix

• hs4://audit/recent

• hs4://state/summary

• hs4://catalog/aliases

• hs4://agent/contract

• hs4://admin/users

• hs4://admin/interfaces

• hs4://admin/plugins

• hs4://admin/cameras/config

• hs4://admin/policy/state (includes admin execution mode and related routing policy state)

• hs4://admin/audit/diff

Prompts

• hs4_safe_control

• hs4_scene_operator

• hs4_diagnostics

• hs4_agent_contract

• hs4_admin_change_control

• hs4_admin_backup_restore

• hs4_admin_plugin_lifecycle

Guarded Write Model

Mutating tools are policy-gated by default.

Base guard requirements for all mutating tools:

• confirm=true required (unless dry-run)

• intent and reason required (unless dry-run)

• Global read-only mode via HS4_SAFE_MODE=read_only

• Optional allowlists for device refs, event ids, script ids, camera ids, plugin functions

• Mutation attempts and outcomes are audit-logged

Admin tool guard model (hs4.admin.*):

• Inputs include operationTier, domain, maintenanceWindowId, changeTicket, and riskLevel

• operationTier currently defaults to operator

• When operationTier=admin, policy enforces:

• HS4_ADMIN_ENABLED=true

• Domain-specific admin flag enabled for the selected domain

• maintenanceWindowId present (and matching configured allowlist/required id when set)

• changeTicket present when HS4_ADMIN_REQUIRE_CHANGE_TICKET=true

Admin Execution Modes

Admin tools support three execution routing modes:

• adapter (default): use adapter-backed admin execution paths first.

• direct: use direct HS4 admin execution paths.

• auto: try direct execution and cache unsupported operations so subsequent calls route straight to adapter.

Execution routing is controlled by:

• HS4_ADMIN_EXECUTION_MODE default: adapter

• HS4_ADMIN_DIRECT_FALLBACK default: true (allow direct/auto paths to fall back to adapter when direct execution is unsupported)

• HS4_ADMIN_CAPABILITY_CACHE_TTL_SEC default: 300 (cache TTL, in seconds, for unsupported direct-operation capability checks)

Production recommendation:

• Keep HS4_ADMIN_EXECUTION_MODE=adapter, HS4_ADMIN_DIRECT_FALLBACK=true, and HS4_ADMIN_CAPABILITY_CACHE_TTL_SEC=300 unless you have a validated operational reason to force direct.

• hs4://admin/policy/state reports the active admin execution mode and related routing policy state so operators can verify runtime behavior.

Two-phase mutation model (hs4.change.*):

• hs4.change.prepare validates and stages a mutation as a dry-run plan.

• hs4.change.commit executes the prepared token if policy checks still pass.

• Prepared tokens are TTL-bound and can be persisted across restarts.

Device write reliability (hs4.devices.set):

• Default mutation mode is control_value; use set_status only when explicitly required.

• verify=true by default; writes are followed by targeted fresh-state readback.

• mode=set_status with a value may be auto-switched to control_value when control pairs indicate that path is safer.

• If set_status does not converge, the server attempts a guarded control_value fallback when feasible.

• Non-converged writes return HS4_ERROR instead of reporting a false success.

• Successful write responses include convergence context (requestedMode, mode, verification, optional modeAutoSwitch, optional fallback).

• dryRun=true validates policy and schema only; it does not perform live write verification.

Resolver and intent targeting behavior:

• hs4.resolve.devices now returns recommended=true on the best mutation target and includes recommendedRef.

• For ambiguous parent/master vs endpoint matches, resolver ranking prefers actionable endpoints (for example child refs with control pairs) unless the query explicitly asks for master, scene, parent, or root.

• hs4.intent.device_set_by_name and device-fallback hs4.intent.scene_activate include resolution metadata and can emit warnings with code PARENT_OR_WRAPPER_TARGET when a wrapper/master target is chosen while an endpoint alternative exists.

• hs4.intent.scene_activate supports deterministic path control with preferPath (auto, event, device_fallback).

• hs4.intent.scene_activate returns selection metadata (selectedPath, reason, topEventScore, topDeviceScore, eventMinScore) so clients can explain why an event or device fallback path was selected.

Actionable error contract (all tools):

• Every error includes: code, message, retryable, fixHint, suggestedNextToolCalls.

• Tool-specific context remains under details.

Contract Naming

Tool names in this project follow the hs4.* and hs4.admin.* contract shown above.

Admin payload delta example

Standard script call:

{
  "command": "my_script(arg1)",
  "confirm": true,
  "intent": "recover interface",
  "reason": "operator request"
}

Admin mutation call:

{
  "command": "my_script(arg1)",
  "confirm": true,
  "intent": "recover interface",
  "reason": "operator request",
  "operationTier": "admin",
  "domain": "system",
  "maintenanceWindowId": "MW-2026-02-23-02",
  "changeTicket": "CHG-4821",
  "riskLevel": "medium"
}

Detailed Setup and Client Integration

1) Install dependencies

npm install

2) Configure env

cp .env.example .env
# edit values as needed

3) Run in stdio mode (default)

npm run dev

Client Setup

This server is primarily designed to be used as an MCP stdio server (the client spawns node dist/index.js). HTTP mode is optional and mainly useful when a client only supports streamable HTTP MCP.

Common stdio config pattern

• Command: node

• Args: <absolute-path>/dist/index.js

• Env: set HS4_* and MCP_* variables (do not put credentials in HS4_BASE_URL)

Example environment values:

{
  "HS4_BASE_URL": "http://127.0.0.1",
  "HS4_REQUIRE_CONFIRM": "true",
  "HS4_SAFE_MODE": "read_write",
  "MCP_LOG_LEVEL": "info"
}

Codex CLI (recommended)

Register:

codex mcp add hs4 \
  --env HS4_BASE_URL=http://127.0.0.1 \
  --env HS4_REQUIRE_CONFIRM=true \
  --env HS4_SAFE_MODE=read_write \
  --env MCP_LOG_LEVEL=info \
  -- node /absolute/path/to/mcp-hs4/dist/index.js

Verify registration:

codex mcp list
codex mcp get hs4 --json

Prompt-level test:

codex exec --skip-git-repo-check -C /absolute/path/to/mcp-hs4 \
  "Use only hs4 MCP tools. Run hs4.selftest.run and summarize any warnings."

LLM Prompt Cookbook

Use these prompts as copy/paste starters for Codex or other MCP-capable agents. Device names shown here are examples; replace them with names from your own HS4 installation.

1. Deterministic event-first scene activation

Use only hs4 MCP tools.
Objective: activate "movie time".

Workflow:
1) Dry-run `hs4.intent.scene_activate` with:
   - objective: "movie time"
   - preferPath: "event"
   - execute: false
   - dryRun: true
   - confirm: true
   - intent: "Activate movie time scene"
   - reason: "Event-first deterministic scene activation"
2) If step 1 returns NOT_FOUND, run a second dry-run with preferPath: "device_fallback".
3) Execute only the successful path (`execute: true`, `dryRun: false`).
4) Report: `path`, `selection.selectedPath`, `selection.reason`, and any `warnings`.

2. Deterministic device-fallback scene activation

Use only hs4 MCP tools.
Objective: activate "coffee bar" using direct device fallback.

Workflow:
1) Dry-run `hs4.intent.scene_activate` with:
   - objective: "coffee bar"
   - preferPath: "device_fallback"
   - fallbackDeviceValue: 99
   - execute: false
   - dryRun: true
   - confirm: true
   - intent: "Direct device fallback activation"
   - reason: "Prefer endpoint control over event path"
2) Execute the same call only if dry-run succeeds.
3) Return `selection` metadata and any `PARENT_OR_WRAPPER_TARGET` warnings.

3. Endpoint-first light control (avoid wrapper/master ghost success)

Use only hs4 MCP tools.
Goal: turn on coffee bar and bar overhead to max.

Workflow:
1) Resolve candidates with `hs4.resolve.devices` for "coffee bar" and "bar overhead light", `includeEvidence=true`.
2) Choose each query's `recommendedRef` when available.
3) Write with `hs4.devices.set` using:
   - mode: "control_value"
   - value: 99
   - verify: true
   - confirm: true
   - intent/reason filled
4) Immediately read back using `hs4.devices.get` (`includeControls=true`) for written refs.
5) Report per-ref: requested mode, applied mode, verification result, status, and value.

4. Wrapper/master-safe intent flow

Use only hs4 MCP tools.
Goal: act on "bar overhead light master" safely.

Workflow:
1) Run `hs4.intent.device_set_by_name` dry-run with query "bar overhead light master", mode "control_value", value 99.
2) If warnings include code `PARENT_OR_WRAPPER_TARGET`, re-run dry-run using the warning `suggestedRef` with `hs4.devices.set`.
3) Execute only after the second dry-run confirms endpoint targeting.
4) Return both runs and explain which target was committed and why.

5. Physical-state mismatch recovery prompt

Use only hs4 MCP tools.
User says: "HS4 reports on, but the light is physically off."

Workflow:
1) Read current state with `hs4.devices.get` (`includeControls=true`).
2) Apply recovery pulse with `hs4.devices.set` (`mode=control_value`, `value=0`, `verify=true`) then `value=99`, both with confirm/intent/reason.
3) Re-read state after each write.
4) If still mismatched, run `hs4.intent.scene_activate` dry-run with `preferPath=device_fallback`, then execute if clean.
5) Report exact tool outputs and where convergence failed or succeeded.

Claude Desktop

Add an MCP server entry (client UI/paths vary by OS and version; look for an MCP servers config section). Most installations accept a config shaped like:

{
  "mcpServers": {
    "hs4": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-hs4/dist/index.js"],
      "env": {
        "HS4_BASE_URL": "http://127.0.0.1",
        "HS4_REQUIRE_CONFIRM": "true",
        "HS4_SAFE_MODE": "read_write",
        "MCP_LOG_LEVEL": "info"
      }
    }
  }
}

Cursor

Cursor’s MCP UI/config evolves quickly; use the same stdio pattern:

• Add MCP server named hs4

• Command node

• Args .../dist/index.js

• Env includes HS4_BASE_URL, HS4_REQUIRE_CONFIRM, HS4_SAFE_MODE

Cline (VS Code)

Cline’s MCP settings also evolve; use the same stdio pattern:

• Add MCP server named hs4

• Command node

• Args .../dist/index.js

• Env includes HS4_BASE_URL, HS4_REQUIRE_CONFIRM, HS4_SAFE_MODE

4) Optional: run as HTTP MCP service

MCP_TRANSPORT=http MCP_HTTP_HOST=127.0.0.1 MCP_HTTP_PORT=7422 npm run dev

Health endpoint in HTTP mode:

curl http://127.0.0.1:7422/healthz

When exposing beyond loopback, set an auth token and include Authorization: Bearer <token> on POST /mcp (and /healthz unless disabled):

MCP_TRANSPORT=http \
MCP_HTTP_HOST=0.0.0.0 \
MCP_HTTP_ALLOW_NON_LOOPBACK=true \
MCP_HTTP_AUTH_TOKEN=replace-me \
npm run dev

HTTP Client Compatibility (JSON-only clients)

Some MCP clients send Accept: application/json only on POST /mcp.

• MCP_HTTP_ACCEPT_MODE=compat (default) allows these clients.

• MCP_HTTP_ALLOW_JSON_ONLY=true (default) enables a compatibility fallback that still preserves streamable clients.

• MCP_HTTP_ACCEPT_MODE=strict enforces explicit application/json and text/event-stream.

Compatibility probes:

# JSON-only client probe (should pass in compat mode)
curl -si -X POST http://127.0.0.1:7422/mcp \
  -H 'content-type: application/json' \
  -H 'accept: application/json' \
  --data '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"diag","version":"0"}}}'

# Strict streamable probe
curl -si -X POST http://127.0.0.1:7422/mcp \
  -H 'content-type: application/json' \
  -H 'accept: application/json, text/event-stream' \
  --data '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"diag","version":"0"}}}'

Token-protected probe:

curl -si -X POST http://127.0.0.1:7422/mcp \
  -H 'content-type: application/json' \
  -H 'accept: application/json' \
  -H 'authorization: Bearer replace-me' \
  --data '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"diag","version":"0"}}}'

Build and Test

npm run typecheck
npm run build
npm test

Environment Variables

See .env.example for complete list. Important ones:

• HS4_BASE_URL default: http://127.0.0.1

• HS4_USER, HS4_PASS

• HS4_SAFE_MODE one of read_write, read_only

• HS4_REQUIRE_CONFIRM default: true

• HS4_MAX_DEVICES_DEFAULT_CAP default: 250 (global default cap for device-heavy reads)

• HS4_STATUS_CACHE_TTL_MS default: 1500 (0 disables status cache)

• HS4_SCRIPT_PAGE_PATH default: /runscript.html

• HS4_EVENTS_DATA_PATH default: /usr/local/HomeSeer/Data/HomeSeerData_2.json/events.json

• HS4_EVENT_GROUPS_DATA_PATH default: /usr/local/HomeSeer/Data/HomeSeerData_2.json/eventgroups.json

• HS4_ALIAS_LEARNED_ENABLED default: true (enable learned aliases for resolver tools)

• HS4_ALIAS_CONFIG_PATH optional path to alias JSON (device:<ref>, event:<id>, camera:<id> keys)

• HS4_CHANGE_TOKEN_TTL_SEC default: 900

• HS4_CHANGE_TOKEN_MAX_ENTRIES default: 2000

• HS4_CHANGE_TOKEN_PERSIST_PATH optional JSONL persistence path for prepared tokens

• HS4_ALLOWED_DEVICE_REFS, HS4_ALLOWED_EVENT_IDS, HS4_ALLOWED_CAMERA_IDS

• HS4_ALLOWED_SCRIPTS (lower-case ids)

• HS4_ALLOWED_PLUGIN_FUNCTIONS in plugin:function format (lower-case)

• HS4_ADMIN_ENABLED default: false

• HS4_ADMIN_USERS_ENABLED default: false

• HS4_ADMIN_PLUGINS_ENABLED default: false

• HS4_ADMIN_INTERFACES_ENABLED default: false

• HS4_ADMIN_SYSTEM_ENABLED default: false

• HS4_ADMIN_CAMERAS_ENABLED default: false

• HS4_ADMIN_EVENTS_ENABLED default: false

• HS4_ADMIN_CONFIG_ENABLED default: false

• HS4_ADMIN_MAINTENANCE_WINDOW_ID optional strict window id

• HS4_ADMIN_ALLOWED_MAINTENANCE_WINDOW_IDS optional allowlist

• HS4_ADMIN_REQUIRE_CHANGE_TICKET default: true

• HS4_ADMIN_ROLLBACK_ENABLED default: true

• HS4_ADMIN_EXECUTION_MODE one of adapter, direct, auto (default: adapter)

• HS4_ADMIN_DIRECT_FALLBACK default: true (recommended in production to preserve guarded fallback to adapter when direct is unsupported)

• HS4_ADMIN_CAPABILITY_CACHE_TTL_SEC default: 300 (admin routing capability cache TTL in seconds; keep non-zero in production)

• HS4_ADMIN_ALLOWED_USER_IDS, HS4_ADMIN_ALLOWED_PLUGIN_IDS, HS4_ADMIN_ALLOWED_INTERFACE_IDS, HS4_ADMIN_ALLOWED_CATEGORY_IDS

• MCP_TRANSPORT one of stdio, http

• MCP_HTTP_ALLOW_NON_LOOPBACK default: false (must be true to intentionally bind non-loopback HTTP hosts)

• MCP_HTTP_ACCEPT_MODE one of compat, strict (default: compat)

• MCP_HTTP_ALLOW_JSON_ONLY default: true (json-only Accept fallback in compat mode)

• MCP_HTTP_AUTH_TOKEN optional bearer token for HTTP auth (required for non-loopback when MCP_HTTP_AUTH_REQUIRED_NON_LOOPBACK=true)

• MCP_HTTP_AUTH_REQUIRED_NON_LOOPBACK default: true (startup fails on non-loopback HTTP bind without token)

• MCP_HTTP_AUTH_PROTECT_HEALTHZ default: true (health endpoint also requires bearer token when auth is enabled)

• MCP_AUDIT_PERSIST_PATH (optional JSONL audit sink)

HS4 Script Execution Note

hs4.scripts.run uses POST /runscript.html with:

• action=run_script_command

• scriptcommand=<command>

This behavior is based on HS4 UI implementation patterns in /usr/local/HomeSeer/html/runscript.html (path may vary by installation). It is powerful; use strict allowlists in production.

Documentation

• Research: docs/01_research/

• Architecture: docs/02_architecture/

• Operations and hardening: docs/04_operations/

• Admin enhancements backlog: docs/05_roadmap/admin_full_parity.txt

Project Policies

• Contribution guide: CONTRIBUTING.md

• Security policy: SECURITY.md