Use Pi runtime hooks for research context hygiene

extensions/research-tools/resume.ts

@@ -0,0 +1,92 @@
+import { existsSync, readdirSync, readFileSync, statSync } from "node:fs";
+import { join, resolve } from "node:path";
+
+import type { ExtensionAPI, ExtensionContext } from "@mariozechner/pi-coding-agent";
+
+type ResumeArtifact = {
+	path: string;
+	mtimeMs: number;
+};
+
+function collectFiles(root: string, predicate: (path: string) => boolean): ResumeArtifact[] {
+	if (!existsSync(root)) return [];
+	const files: ResumeArtifact[] = [];
+	for (const entry of readdirSync(root, { withFileTypes: true })) {
+		const path = join(root, entry.name);
+		if (entry.isDirectory()) {
+			files.push(...collectFiles(path, predicate));
+			continue;
+		}
+		if (!entry.isFile() || !predicate(path)) continue;
+		try {
+			files.push({ path, mtimeMs: statSync(path).mtimeMs });
+		} catch {}
+	}
+	return files;
+}
+
+function tail(text: string, maxChars: number): string {
+	return text.length <= maxChars ? text : text.slice(text.length - maxChars);
+}
+
+export function buildResumePacket(cwd: string, maxChars = 4_000): string | undefined {
+	const plans = collectFiles(resolve(cwd, "outputs", ".plans"), (path) => path.endsWith(".md"))
+		.sort((a, b) => b.mtimeMs - a.mtimeMs)
+		.slice(0, 3);
+	const stateFiles = collectFiles(resolve(cwd, "outputs", ".state"), (path) => /\.(json|jsonl|md)$/i.test(path))
+		.sort((a, b) => b.mtimeMs - a.mtimeMs)
+		.slice(0, 5);
+	const changelogPath = resolve(cwd, "CHANGELOG.md");
+
+	if (plans.length === 0 && stateFiles.length === 0 && !existsSync(changelogPath)) {
+		return undefined;
+	}
+
+	const lines: string[] = [
+		"[feynman resume packet]",
+		"This is a bounded project-state summary from disk. Prefer these paths over guessing prior workflow state.",
+	];
+
+	if (plans.length > 0) {
+		lines.push("", "Recent plans:");
+		for (const plan of plans) {
+			lines.push(`- ${plan.path}`);
+		}
+		const newestPlan = plans[0]!;
+		try {
+			lines.push("", `Newest plan tail (${newestPlan.path}):`, tail(readFileSync(newestPlan.path, "utf8"), 1_500));
+		} catch {}
+	}
+
+	if (stateFiles.length > 0) {
+		lines.push("", "Recent state files:");
+		for (const file of stateFiles) {
+			lines.push(`- ${file.path}`);
+		}
+	}
+
+	if (existsSync(changelogPath)) {
+		try {
+			lines.push("", "CHANGELOG tail:", tail(readFileSync(changelogPath, "utf8"), 1_200));
+		} catch {}
+	}
+
+	return tail(lines.join("\n"), maxChars);
+}
+
+export function registerResumePacket(pi: ExtensionAPI): void {
+	pi.on("session_start", async (_event, ctx: ExtensionContext) => {
+		if (process.env.FEYNMAN_RESUME_PACKET === "off") return;
+		const packet = buildResumePacket(ctx.cwd);
+		if (!packet) return;
+		pi.sendMessage(
+			{
+				customType: "feynman_resume_packet",
+				content: packet,
+				display: false,
+				details: { source: "outputs/.plans outputs/.state CHANGELOG.md" },
+			},
+			{ triggerTurn: false, deliverAs: "nextTurn" },
+		);
+	});
+}