Fix session file and elapsed replay state

frontend/app/app/api/claw/files/route.ts

@@ -16,15 +16,24 @@ export async function GET(req: Request) {
 
 	const url = new URL(req.url);
 	const requestedPath = url.searchParams.get("path");
-	const sessionId = url.searchParams.get("session_id");
+	const sessionId = normalizeSessionId(url.searchParams.get("session_id"));
 	if (!requestedPath && sessionId) {
 		return Response.json({
+			session_id: sessionId,
 			input: await listSessionFiles(account.id, sessionId, "input"),
 			output: await listSessionFiles(account.id, sessionId, "output"),
 		});
 	}
 	if (!requestedPath) {
-		return Response.json({ error: "缺少文件路径或会话 ID" }, { status: 400 });
+		const latestSessionId = await findLatestSessionId(account.id);
+		if (!latestSessionId) {
+			return Response.json({ session_id: null, input: [], output: [] });
+		}
+		return Response.json({
+			session_id: latestSessionId,
+			input: await listSessionFiles(account.id, latestSessionId, "input"),
+			output: await listSessionFiles(account.id, latestSessionId, "output"),
+		});
 	}
 
 	const accountRoot = path.resolve(accountBaseRoot(account.id));
@@ -87,6 +96,37 @@ async function listSessionFiles(
 	}
 }
 
+function normalizeSessionId(value: string | null) {
+	const trimmed = value?.trim();
+	return trimmed || null;
+}
+
+async function findLatestSessionId(accountId: string) {
+	const sessionsRoot = path.join(accountBaseRoot(accountId), "sessions");
+	try {
+		const entries = await readdir(sessionsRoot, { withFileTypes: true });
+		const candidates = await Promise.all(
+			entries
+				.filter((entry) => entry.isDirectory())
+				.map(async (entry) => {
+					const sessionDir = path.join(sessionsRoot, entry.name);
+					const sessionFile = path.join(sessionDir, "session.json");
+					try {
+						const sessionStat = await stat(sessionFile);
+						return { id: entry.name, modifiedAt: sessionStat.mtimeMs };
+					} catch {
+						const dirStat = await stat(sessionDir);
+						return { id: entry.name, modifiedAt: dirStat.mtimeMs };
+					}
+				}),
+		);
+		candidates.sort((a, b) => b.modifiedAt - a.modifiedAt);
+		return candidates.at(0)?.id ?? null;
+	} catch {
+		return null;
+	}
+}
+
 function contentTypeFor(filePath: string) {
 	const ext = path.extname(filePath).toLowerCase();
 	if (ext === ".json") return "application/json; charset=utf-8";