fix: load all thread pages in thread lists (#1044)

* fix(frontend): load all thread pages in thread lists

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

frontend/src/app/mock/api/threads/search/route.ts

@@ -1,27 +1,84 @@
 import fs from "fs";
 import path from "path";
 
-export function POST() {
+type ThreadSearchRequest = {
+  limit?: number;
+  offset?: number;
+  sortBy?: "updated_at" | "created_at";
+  sortOrder?: "asc" | "desc";
+};
+
+type MockThreadSearchResult = Record<string, unknown> & {
+  thread_id: string;
+  updated_at: string | undefined;
+};
+
+export async function POST(request: Request) {
+  const body = ((await request.json().catch(() => ({}))) ?? {}) as ThreadSearchRequest;
+
+  const rawLimit = body.limit;
+  let limit = 50;
+  if (typeof rawLimit === "number") {
+    const normalizedLimit = Math.max(0, Math.floor(rawLimit));
+    if (!Number.isNaN(normalizedLimit)) {
+      limit = normalizedLimit;
+    }
+  }
+
+  const rawOffset = body.offset;
+  let offset = 0;
+  if (typeof rawOffset === "number") {
+    const normalizedOffset = Math.max(0, Math.floor(rawOffset));
+    if (!Number.isNaN(normalizedOffset)) {
+      offset = normalizedOffset;
+    }
+  }
+  const sortBy = body.sortBy ?? "updated_at";
+  const sortOrder = body.sortOrder ?? "desc";
+
   const threadsDir = fs.readdirSync(
     path.resolve(process.cwd(), "public/demo/threads"),
     {
       withFileTypes: true,
     },
   );
+
   const threadData = threadsDir
-    .map((threadId) => {
+    .map<MockThreadSearchResult | null>((threadId) => {
       if (threadId.isDirectory() && !threadId.name.startsWith(".")) {
-        const threadData = fs.readFileSync(
-          path.resolve(`public/demo/threads/${threadId.name}/thread.json`),
-          "utf8",
-        );
+        const threadData = JSON.parse(
+          fs.readFileSync(
+            path.resolve(`public/demo/threads/${threadId.name}/thread.json`),
+            "utf8",
+          ),
+        ) as Record<string, unknown>;
+
         return {
+          ...threadData,
           thread_id: threadId.name,
-          values: JSON.parse(threadData).values,
+          updated_at:
+            typeof threadData.updated_at === "string"
+              ? threadData.updated_at
+              : typeof threadData.created_at === "string"
+                ? threadData.created_at
+                : undefined,
         };
       }
-      return false;
+      return null;
     })
-    .filter(Boolean);
-  return Response.json(threadData);
+    .filter((thread): thread is MockThreadSearchResult => thread !== null)
+    .sort((a, b) => {
+      const aTimestamp = a[sortBy];
+      const bTimestamp = b[sortBy];
+      const aParsed =
+        typeof aTimestamp === "string" ? Date.parse(aTimestamp) : 0;
+      const bParsed =
+        typeof bTimestamp === "string" ? Date.parse(bTimestamp) : 0;
+      const aValue = Number.isNaN(aParsed) ? 0 : aParsed;
+      const bValue = Number.isNaN(bParsed) ? 0 : bParsed;
+      return sortOrder === "asc" ? aValue - bValue : bValue - aValue;
+    });
+
+  const pagedThreads = threadData.slice(offset, offset + limit);
+  return Response.json(pagedThreads);
 }