73 lines
2.3 KiB
TypeScript
73 lines
2.3 KiB
TypeScript
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/**
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* Pure helpers for AI chat in-session jump navigation (user-turn TOC).
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*/
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export const CHAT_JUMP_MIN_ENTRIES = 3;
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export const CHAT_JUMP_LABEL_MAX = 36;
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export type ChatJumpMessage = {
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id: string;
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role: string;
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content?: string;
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};
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export type ChatJumpEntry = {
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messageId: string;
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label: string;
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/** 1-based index among user turns */
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index: number;
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};
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export function chatMessageDomId(messageId: string): string {
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return `ai-chat-msg-${messageId}`;
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}
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export function truncateChatJumpLabel(text: string, maxLen = CHAT_JUMP_LABEL_MAX): string {
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const normalized = text.replace(/\s+/g, ' ').trim();
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if (!normalized) return '';
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if (normalized.length <= maxLen) return normalized;
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const ellipsis = '...';
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return `${normalized.slice(0, Math.max(1, maxLen - ellipsis.length)).trimEnd()}${ellipsis}`;
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}
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export function buildChatJumpEntries(
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messages: ReadonlyArray<ChatJumpMessage>,
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options?: {
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minEntries?: number;
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maxLabelLen?: number;
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emptyLabel?: string;
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},
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): ChatJumpEntry[] {
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const minEntries = options?.minEntries ?? CHAT_JUMP_MIN_ENTRIES;
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const maxLabelLen = options?.maxLabelLen ?? CHAT_JUMP_LABEL_MAX;
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const emptyLabel = options?.emptyLabel ?? '...';
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const entries: ChatJumpEntry[] = [];
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for (const message of messages) {
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if (message.role !== 'user') continue;
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const label = truncateChatJumpLabel(message.content ?? '', maxLabelLen) || emptyLabel;
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entries.push({
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messageId: message.id,
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label,
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index: entries.length + 1,
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});
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}
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return entries.length >= minEntries ? entries : [];
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}
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/**
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* Expand the rendered tail window so a jump target is mounted in the DOM.
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* Call again whenever the message list grows while the jump target remains
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* active; a one-shot expand at jump time is not enough if the tail is
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* `slice(-count)` and later appends would otherwise slide the window forward.
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*/
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export function resolveTailCountForJumpTarget(
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visibleMessages: ReadonlyArray<{ id: string }>,
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targetMessageId: string,
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currentTailCount: number,
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): number {
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const targetIndex = visibleMessages.findIndex((message) => message.id === targetMessageId);
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if (targetIndex < 0) return currentTailCount;
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const requiredTail = visibleMessages.length - targetIndex;
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return Math.max(currentTailCount, requiredTail);
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}
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