89 lines
2.9 KiB
TypeScript
89 lines
2.9 KiB
TypeScript
import { formatModerationTextEvidenceForPrompt } from "./indonesianTextNormalizer.js";
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import { formatMediaEvidenceForPrompt } from "../message-capture/messageMetadata.js";
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import type { MessageRecord } from "../message-capture/types.js";
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import { encoding_for_model as encodingForModel } from "tiktoken";
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export interface ConversationContextInput {
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contextBefore: MessageRecord[];
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targets: MessageRecord[];
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maxTokens: number;
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}
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let _encoder: ReturnType<typeof encodingForModel> | null = null;
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function getEncoder(): ReturnType<typeof encodingForModel> {
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if (!_encoder) {
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_encoder = encodingForModel("gpt-4o");
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}
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return _encoder;
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}
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/**
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* Formats a timestamp to ISO 8601 string
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*/
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function formatTimestamp(ms: number): string {
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return new Date(ms).toISOString();
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}
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/**
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* Estimates token count for a string (pessimistic approximation for Indonesian slang & JSON overhead)
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*/
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export function estimateTokens(text: string): number {
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// Use tiktoken for accurate token counting (+15 overhead for JSON structure)
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return getEncoder().encode(text).length + 15;
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}
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/**
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* Formats a single message for context or target display
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*/
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export async function formatMessageForPrompt(
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msg: MessageRecord,
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label: "context" | "target",
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): Promise<string> {
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const content = msg.edited_content ?? msg.content;
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const timestamp = formatTimestamp(msg.created_at);
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const textEvidence = await formatModerationTextEvidenceForPrompt(content);
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const textSuffix = textEvidence ? ` ${textEvidence}` : "";
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const mediaEvidence = formatMediaEvidenceForPrompt(msg.metadata);
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const mediaSuffix = mediaEvidence ? ` ${mediaEvidence}` : "";
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return `[${label}] id=${msg.id} time=${timestamp} user=${msg.username}: ${content}${textSuffix}${mediaSuffix}`;
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}
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/**
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* Builds conversation historical context without including targets.
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* Calculates how much token budget targets use, and fills the rest with context.
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*/
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export async function buildConversationContext(
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input: ConversationContextInput,
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): Promise<string[]> {
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const { contextBefore, targets, maxTokens } = input;
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// Calculate tokens used by targets (parallel)
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const targetLines = await Promise.all(
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targets.map((msg) => formatMessageForPrompt(msg, "target")),
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);
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let usedTokens = targetLines.reduce(
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(sum, line) => sum + estimateTokens(line),
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0,
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);
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const contextLines = await Promise.all(
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contextBefore.map((msg) => formatMessageForPrompt(msg, "context")),
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);
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const selectedContextLines: string[] = [];
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// Go backwards through context, taking most recent first
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for (let i = contextLines.length - 1; i >= 0; i--) {
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const line = contextLines[i];
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const lineTokens = estimateTokens(line);
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if (usedTokens + lineTokens <= maxTokens) {
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// Unshift so oldest context is first in the array
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selectedContextLines.unshift(line);
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usedTokens += lineTokens;
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}
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}
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return selectedContextLines;
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}
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