pi-auto-reinject/src/kept.ts

import type { SessionEntry } from "@earendil-works/pi-coding-agent";
import { parseSkillBlocksFromText } from "./detect.js";
import type { TrackedSkill } from "./state.js";

/** Branch slice from firstKeptEntryId through tail (SPEC §6.4). */
export function getKeptEntries(branch: SessionEntry[], firstKeptEntryId: string): SessionEntry[] {
	const startIndex = branch.findIndex((entry) => entry.id === firstKeptEntryId);
	if (startIndex < 0) {
		return [];
	}
	return branch.slice(startIndex);
}

function extractUserMessageText(content: unknown): string {
	if (typeof content === "string") {
		return content;
	}
	if (!Array.isArray(content)) {
		return "";
	}
	const parts: string[] = [];
	for (const part of content) {
		if (!part || typeof part !== "object") {
			continue;
		}
		const block = part as { type?: string; text?: string };
		if (block.type === "text" && typeof block.text === "string") {
			parts.push(block.text);
		}
	}
	return parts.join("\n");
}

/** Skill names already present as blocks in kept user messages (SPEC §6.4). */
export function skillsPresentInKeptWindow(
	keptEntries: SessionEntry[],
	skillNames: readonly string[],
): Set<string> {
	const present = new Set<string>();
	const namesToCheck = new Set(skillNames);
	if (namesToCheck.size === 0) {
		return present;
	}

	for (const entry of keptEntries) {
		if (entry.type !== "message" || entry.message.role !== "user") {
			continue;
		}
		const text = extractUserMessageText(entry.message.content);
		for (const block of parseSkillBlocksFromText(text)) {
			if (namesToCheck.has(block.name)) {
				present.add(block.name);
			}
		}
	}
	return present;
}

/** Tracked skills missing from kept window but still registered (SPEC §5.2, §6.4). */
export function filterSkillsNeedingReinject(
	tracked: readonly TrackedSkill[],
	keptPresent: ReadonlySet<string>,
	registeredNames: ReadonlySet<string>,
): string[] {
	const needing: string[] = [];
	for (const skill of tracked) {
		if (registeredNames.has(skill.name) && !keptPresent.has(skill.name)) {
			needing.push(skill.name);
		}
	}
	return needing;
}