src/vs/platform/agentHost/common/state/chatAttachmentContext.ts
80 LOC · 79 covered · 1 uncovered · 10 ranges · 1057 concepts · 7 introducers · 512 tests
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/*---------------------------------------------------------------------------------------------
chatAttachmentContext.ts ×3
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import { MessageAttachmentKind, ResponsePartKind, type MessageChatAttachment, type SimpleMessageAttachment, type Turn } from './protocol/state.js';
/**
* Model-facing preamble that frames the resolved transcript for the SDK. It is
* intentionally hard-coded English (like Claude's `<system-reminder>` text):
* this string is consumed by the model, not shown in the UI, so it must not be
* localized.
*/
const CHAT_TRANSCRIPT_PREAMBLE =
'The user referenced another chat in the same session. ' +
'The transcript below is that chat up to the selected turn, provided as background context. ' +
'Treat it as reference material that may or may not be relevant to the new question.';
/**
* Returns the referenced chat's turns bounded through {@link endTurn}, inclusive.
* Throws when {@link endTurn} is not a retained completed turn.
*/
export function boundChatTranscriptTurns(turns: readonly Turn[], endTurn: string): readonly Turn[] {
if (index < 0) {
throw new Error(`Chat attachment endTurn ${endTurn} was not found in the retained transcript.`);
chatAttachmentContext.ts ×1
}
}
/**
* Formats bounded transcript turns into a plain-text conversation for the
* model. Only user message text and assistant markdown are rendered; tool
* calls, reasoning, and other parts are omitted to keep the context bounded.
*
* This never expands nested attachments, so a {@link MessageChatAttachment}
* referenced inside the source transcript is not recursively resolved.
*/
export function formatChatTranscript(turns: readonly Turn[]): string {
for (const turn of turns) {
const userText = turn.message?.text?.trim();
if (userText) {
blocks.push(`User: ${userText}`);
}
const assistantText = turn.responseParts
.map(part => (part.kind === ResponsePartKind.Markdown ? part.content : ''))
.join('')
.trim();
if (assistantText) {
blocks.push(`Assistant: ${assistantText}`);
}
}
return blocks.join('\n\n');
}
/**
* Resolves a {@link MessageChatAttachment} into an SDK-compatible
* {@link SimpleMessageAttachment}: the bounded transcript rendered as the
* attachment's {@link SimpleMessageAttachment.modelRepresentation}. Every
* provider adapter already inlines a `Simple` attachment's model
* representation, so this keeps transcript formatting in one place instead of
* duplicating it per agent.
*
* The resolution is non-recursive: it renders {@link sourceTurns} directly and
* never re-resolves chat attachments found within them.
*/
export function resolveChatAttachment(attachment: MessageChatAttachment, sourceTurns: readonly Turn[]): SimpleMessageAttachment {
const bounded = boundChatTranscriptTurns(sourceTurns, attachment.endTurn);
chatAttachmentContext.ts ×2
const transcript = formatChatTranscript(bounded);
const modelRepresentation = transcript
: CHAT_TRANSCRIPT_PREAMBLE;
type: MessageAttachmentKind.Simple,
label: attachment.label,
modelRepresentation,
...(attachment.range !== undefined ? { range: attachment.range } : {}),
};
}