Chat agents

Maintain conversation history, stream replies, and coordinate model and tool calls.

Libraries Runtime.AIChat Runtime.Think
npm @cloudflare/ai-chat 0.11.0
Upstream/API Think experimental; see the F# binding boundary below

Conversation and execution

The chat layer owns the conversation, message persistence, and streaming response lifecycle. A model provider supplies inference; MCP and Code Mode supply ways to use tools. Files and repository history can live in their own workspaces and Artifacts repositories.

The upstream AI Chat guide describes resumable streams, persistent messages, tool approval, and recovery. Configure conversation identity and history retention separately from the execution environment used by a tool call.

F# binding boundary

The current bindings describe AIChatAgent and Think as F# interfaces. They cannot directly be used as imported base classes for an F# class. Exported helper functions are available from F#, including the history migration below. The Agents SDK page demonstrates the supported F# Durable Object lifecycle pattern.

Chat History Upgrade

autoTransformMessages converts a conversation saved in the AI SDK v4 message format to v5 UIMessage objects. Apps built on v5 can then read chat history stored before the upgrade.

open Fable.Core

module Workers = FSharp.CloudEdge.Runtime.Workers
module Migration = FSharp.CloudEdge.Runtime.AIChat.AiChatV5Migration

[<ExportDefault>]
let worker: Workers.ExportedHandler<obj, obj, obj, obj> =
    Workers.ExportedHandler.Create(
        fetch = fun request _ _ ->
            async {
                let! stored = request.json<obj[]> () |> Async.AwaitPromise
                let upgraded = Migration.Exports.autoTransformMessages stored
                return Workers.Exports.Response.json upgraded
            }
            |> Async.StartAsPromise
            |> U2.Case1
    )

Emitted JavaScript

import { awaitPromise, startAsPromise } from "./fable_modules/fable-library-js.5.13.0/Async.js";
import { singleton } from "./fable_modules/fable-library-js.5.13.0/AsyncBuilder.js";
import { autoTransformMessages } from "@cloudflare/ai-chat/ai-chat-v5-migration";

export const worker = {
    fetch: (request, _arg, _arg_1) => startAsPromise(singleton.Delay(() => singleton.Bind(awaitPromise(request.json()), (_arg_2) => {
        const upgraded = autoTransformMessages(_arg_2);
        return singleton.Return(globalThis.Response.json(upgraded));
    }))),
};

export default worker;

History migrations

Treat persisted conversation history as application data with a version. When upgrading the message representation, test the conversion against existing conversations before changing the code that reads them. The example demonstrates the v4-to-v5 conversion helper; it is not a complete chat agent or a promise that arbitrary later message formats need no migration.

Testing and feedback

Useful test cases include history migration with stored messages and chat lifecycle behavior through your JavaScript adapter.

Verify bindings explains how to run checks and report an issue. Include a small reproduction and the package versions used; working examples are welcome too.

NuGet packages

Runtime.AIChat 0.1.0, Runtime.Think 0.1.0, Runtime.Workers 0.1.0.

See installation and release availability.

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