# Migration Guide

Source: https://langbot.app/docs/en/plugin/dev/migration

This tutorial highlights certain considerations. Please read the current version plugin tutorial first, then use this document as a reference for plugin migration.

## Migrating from 3.x Supported Asynchronous Plugins

> Plugin characteristics::
>
> - Main time period: 2024.2 \~ 2025.8
> - Registration method: Using `@handler` decorators to register event listeners and `@llm_func` decorators to register content functions (tools) in the plugin class in `main.py`; all handler functions are asynchronous functions (async def)

- Plugin and component registration method: Changed from the previous single plugin class decorator registration method to manifest file registration method. See [Manifest File](https://langbot.app/docs/en/plugin/dev/basic-info.md); and separated different types of components independently. For details, see [Adding Components](https://langbot.app/docs/en/plugin/dev/components/add.md).
- Message chain entities: Now refactored. The construction method of each message chain element now requires explicit passing of **named parameters**. See [Message Platform Entities](https://langbot.app/docs/en/plugin/dev/apis/messages.md).
- Event listeners: Provides backward compatibility, but no longer provides `query: Query` object in context. For details, see [Pipeline Events](https://langbot.app/docs/en/plugin/dev/apis/pipeline-events.md).
- Command components: Now refactored. See [Command Components](https://langbot.app/docs/en/plugin/dev/components/command.md).

## Migrating from 2.x and 3.x Supported Synchronous Plugins

> Plugin characteristics::
>
> - Main time period: 2023.1 \~ 2024.2
> - Registration method: Using `@on` decorators to register event listeners and `@func` decorators to register content functions (tools) in the plugin class in `main.py`; all handler functions are synchronous functions (def)

- Synchronous to asynchronous: Plugin runtime has now changed to fully asynchronous (based on asyncio). Please change all plugin code involving IO operations to asynchronous writing.
- For detailed content, please refer to the above 3.x asynchronous plugin migration guide.