Merge commit '67b361f0e99135c578d5764c915b413f457dd67a' as 'third_party/pi'

third_party/pi/packages/agent/src/harness/compaction/utils.ts

@@ -0,0 +1,132 @@
+import { contentText, type Message } from "@earendil-works/pi-ai";
+import type { AgentMessage } from "../../types.ts";
+
+/** File paths touched by a session branch or compaction range. */
+export interface FileOperations {
+	/** Files read but not necessarily modified. */
+	read: Set<string>;
+	/** Files written by full-file write operations. */
+	written: Set<string>;
+	/** Files modified by edit operations. */
+	edited: Set<string>;
+}
+
+/** Create an empty file-operation accumulator. */
+export function createFileOps(): FileOperations {
+	return {
+		read: new Set(),
+		written: new Set(),
+		edited: new Set(),
+	};
+}
+
+/** Add file operations from assistant tool calls to an accumulator. */
+export function extractFileOpsFromMessage(message: AgentMessage, fileOps: FileOperations): void {
+	if (message.role !== "assistant") return;
+	if (!("content" in message) || !Array.isArray(message.content)) return;
+
+	for (const block of message.content) {
+		if (typeof block !== "object" || block === null) continue;
+		if (!("type" in block) || block.type !== "toolCall") continue;
+		if (!("arguments" in block) || !("name" in block)) continue;
+
+		const args = block.arguments as Record<string, unknown> | undefined;
+		if (!args) continue;
+
+		const path = typeof args.path === "string" ? args.path : undefined;
+		if (!path) continue;
+
+		switch (block.name) {
+			case "read":
+				fileOps.read.add(path);
+				break;
+			case "write":
+				fileOps.written.add(path);
+				break;
+			case "edit":
+				fileOps.edited.add(path);
+				break;
+		}
+	}
+}
+
+/** Compute sorted read-only and modified file lists from accumulated operations. */
+export function computeFileLists(fileOps: FileOperations): { readFiles: string[]; modifiedFiles: string[] } {
+	const modified = new Set([...fileOps.edited, ...fileOps.written]);
+	const readOnly = [...fileOps.read].filter((f) => !modified.has(f)).sort();
+	const modifiedFiles = [...modified].sort();
+	return { readFiles: readOnly, modifiedFiles };
+}
+
+/** Format file lists as summary metadata tags. */
+export function formatFileOperations(readFiles: string[], modifiedFiles: string[]): string {
+	const sections: string[] = [];
+	if (readFiles.length > 0) {
+		sections.push(`<read-files>\n${readFiles.join("\n")}\n</read-files>`);
+	}
+	if (modifiedFiles.length > 0) {
+		sections.push(`<modified-files>\n${modifiedFiles.join("\n")}\n</modified-files>`);
+	}
+	if (sections.length === 0) return "";
+	return `\n\n${sections.join("\n\n")}`;
+}
+
+const TOOL_RESULT_MAX_CHARS = 2000;
+
+function safeJsonStringify(value: unknown): string {
+	try {
+		return JSON.stringify(value) ?? "undefined";
+	} catch {
+		return "[unserializable]";
+	}
+}
+
+function truncateForSummary(text: string, maxChars: number): string {
+	if (text.length <= maxChars) return text;
+	const truncatedChars = text.length - maxChars;
+	return `${text.slice(0, maxChars)}\n\n[... ${truncatedChars} more characters truncated]`;
+}
+
+/** Serialize LLM messages to plain text for summarization prompts. */
+export function serializeConversation(messages: Message[]): string {
+	const parts: string[] = [];
+
+	for (const msg of messages) {
+		if (msg.role === "user") {
+			const content = contentText(msg.content, "");
+			if (content) parts.push(`[User]: ${content}`);
+		} else if (msg.role === "assistant") {
+			const thinkingParts: string[] = [];
+			const toolCalls: string[] = [];
+
+			for (const block of msg.content) {
+				if (block.type === "thinking") {
+					thinkingParts.push(block.thinking);
+				} else if (block.type === "toolCall") {
+					const args = block.arguments as Record<string, unknown>;
+					const argsStr = Object.entries(args)
+						.map(([k, v]) => `${k}=${safeJsonStringify(v)}`)
+						.join(", ");
+					toolCalls.push(`${block.name}(${argsStr})`);
+				}
+			}
+
+			if (thinkingParts.length > 0) {
+				parts.push(`[Assistant thinking]: ${thinkingParts.join("\n")}`);
+			}
+			if (msg.content.some((block) => block.type === "text")) {
+				parts.push(`[Assistant]: ${contentText(msg.content)}`);
+			}
+			if (toolCalls.length > 0) {
+				parts.push(`[Assistant tool calls]: ${toolCalls.join("; ")}`);
+			}
+		} else if (msg.role === "toolResult") {
+			const content = contentText(msg.content, "");
+			if (content) {
+				parts.push(`[Tool result]: ${truncateForSummary(content, TOOL_RESULT_MAX_CHARS)}`);
+			}
+		}
+	}
+
+	return parts.join("\n\n");
+}