# SMS Assist (Lessen) — One Open API v2

> SMS Assist, now Lessen, runs the "One" Platform for facilities maintenance, repair, and work-order management across residential and commercial properties. The One Open API v2 is a GraphQL API split into a Client surface (create/track reactive and recurrent work orders, residents, locations, invoices, proposals, Turn/Reno projects) and a Vendor surface (assets, communications, messages, work orders for affiliate technicians), with a rich webhook event catalog, SSO/SCIM, and isolated sandbox and production environments. Legacy REST v1 and Affiliate API v1 were sunset in favor of v2 GraphQL.

## APIs
- [One Open API v2 - Client (GraphQL)](https://meshlive.lessen.com/one-graph-client/graphql): Client work-order, invoice, proposal, resident, location, and Turn/Reno operations.
- [One Open API v2 - Vendor (GraphQL/HTTP)](https://meshlive.lessen.com/one-graph-vendor/graphql): Vendor/affiliate asset, communication, and work-order operations.

## Docs
- [Developer Portal](https://developers.lessen.com/)
- [Documentation home](https://developers.lessen.com/docs/)
- [Client API Overview](https://developers.lessen.com/docs/#/client/overview)
- [Vendor API Overview](https://developers.lessen.com/docs/#/vendor/overview)
- [Authentication (Client)](https://developers.lessen.com/docs/#/client/authentication/client)
- [Authentication (Vendor)](https://developers.lessen.com/docs/#/vendor/authentication/vendor)
- [Environments](https://developers.lessen.com/docs/#/client/environment/client)
- [About Webhooks](https://developers.lessen.com/docs/#/client/guides/webhook/about-webhooks)
- [Webhook Event Topics v2](https://developers.lessen.com/docs/#/client/guides/webhook/webhooks-events-v2)
- [SSO & SCIM](https://developers.lessen.com/docs/#/client/sso/overview)
- [Client Release Notes](https://developers.lessen.com/docs/#/client/releaseNotes/client)
- [Vendor Release Notes](https://developers.lessen.com/docs/#/vendor/releaseNotes/vendor)

## Auth
- Token-based bearer auth. POST HTTP Basic Auth credentials to the environment /token endpoint to obtain an access_token, then send it as a bearer token on every GraphQL request. Tokens expire per `expires_in` (Unix epoch). Unauthorized calls return 401.
- Client token: https://meshlive.lessen.com/one-graph-client/token
- Vendor token: https://meshlive.lessen.com/one-graph-vendor/token

## Environments
- Sandbox/Stage: https://meshstage.lessen.com
- Production: https://meshlive.lessen.com
- GraphiQL explorer: https://meshstage.lessen.com/one-graph-client/ui/graphiql
- Voyager schema map: https://meshstage.lessen.com/one-graph-client/ui/voyager

## Operations
- Status: https://status.lessen.com/
- Blog / Resources: https://www.lessen.com/resources
- Terms of Use: https://www.lessen.com/legal/terms-of-use
- Privacy Policy: https://www.lessen.com/legal/privacy-policy

## Artifacts
- Authentication: authentication/sms-assist-authentication.yml
- Conventions: conventions/sms-assist-conventions.yml
- Lifecycle: lifecycle/sms-assist-lifecycle.yml
- Changelog: changelog/sms-assist-changelog.yml
- Errors: errors/sms-assist-problem-types.yml
- Webhooks: asyncapi/sms-assist-webhooks.yml
- Sandbox: sandbox/sms-assist-sandbox.yml
- Data model: data-model/sms-assist-data-model.yml
- Conformance: conformance/sms-assist-conformance.yml
- MCP (candidate): mcp/sms-assist-mcp.yml
- Agent skills: skills/_index.yml