---
title: Drivers and Adapters
description: Implement a host profile without importing host or transport policy into the portable Kernel.
---

## Runtime Driver checklist

A real Driver provides scheduling, wakeups, monotonic timers, joins,
cooperative cancellation, and shutdown translation. Target compilation alone is
not runtime proof; each profile needs scheduler, timer, readiness, cancellation,
and shutdown smoke evidence.

## Execution Adapter checklist

An Adapter owns:

- the execution-class identifier advertised to Plan validation;
- Plugin factory or process generation;
- typed endpoint creation and Adapter-specific dispatch;
- framing, isolation, and resource ownership;
- failure classification and restart cleanup; and
- conformance against the published runtime Interface.

## Current owners

| Implementation | Repository |
| --- | --- |
| Tokio Runner, native Adapter, browser and WASIp2 Drivers | `LioRael/lenso-runtime-rust` |
| Bun SDK, child-process Adapter, and prepared Host runtime | `LioRael/lenso-bun-adapter` |
| Descriptor code generation and portable value conformance | `LioRael/lenso-protocols` |

The Bun Adapter uses JSON-RPC over HTTP in production and implements Request,
bidirectional Stream, and volatile Event dispatch. Those are Adapter/wire
choices, not Capability or Kernel semantics. Plugin authors use the published
`@lenso/bun` server and `lenso plugin dev`; they do not implement
the handshake or process protocol. See
[Bun Plugin authoring](/docs/core/bun-plugin-authoring) for the complete scaffold and
development path.

The CLI declares and prepares TypeScript/Bun Hosts; `lenso-host-runtime`
assembles the Rust Kernel and Bun/Process Adapters. See [TypeScript Host](/docs/core/typescript-host)
for the entrypoint and current limits.