MentorChatReducer class

The reducer that keeps MentorAgent's built-in in-memory history bounded: it keeps the most recent whole turns that fit in MentorChatReducer.MaxMessages, and every tool call together with its result.

Why not MessageCountingChatReducer. The framework's reducer drops every message that carries a function call or a function result. From the next turn on, the model no longer sees the data a tool read, and answers a follow-up ("and the second one?") by guessing or by calling the tool again. This reducer counts those messages like any other and cuts only where a turn starts.

How it cuts. A turn starts at a user message (one that only answers a tool approval does not start a turn). Turns are kept newest first while they fit; the first that does not fit is dropped with everything older, so a turn is never kept in part. When the newest turn alone is over the budget, its question and its most recent messages are kept. A tool result, or an approval response, whose call was cut away is removed with it: the model never sees a result without the call that produced it. The first system message, if any, is always kept and not counted, as MessageCountingChatReducer does.

It is stateless, so one instance can serve every session. Use it in a history provider of your own: new InMemoryChatHistoryProvider(new() { ChatReducer = new MentorChatReducer(50) }).

Namespace: Novior.MentorAgent.Core. Package: Novior.MentorAgent.

public sealed class MentorChatReducer : IChatReducer

dotnet add package Novior.MentorAgent

public MentorChatReducer(int maxMessages)

Creates a reducer that keeps at most maxMessages messages.

Parameters

• maxMessages: The budget, counting every message except the first system message — tool calls and tool results included. Must be at least 1.

public int MaxMessages { get; }

The most messages the reduced history holds, not counting the first system message.

public Task<IEnumerable<ChatMessage>> ReduceAsync(IEnumerable<ChatMessage> messages, CancellationToken cancellationToken = default)