fix: use searchChatMessages instead of getChatHistory for channel scanning

getChatHistory fails silently in supergroups with hidden history for new
members, returning only system messages. searchChatMessages with document
and photo filters works regardless of history visibility settings.

Also adds getChats call after TDLib client creation to populate the chat
list, preventing 'Chat not found' errors.

worker/src/tdlib/download.ts

@@ -154,114 +154,98 @@ export async function getChannelMessages(
   const photos: TelegramPhoto[] = [];
   const boundary = lastProcessedMessageId ? Number(lastProcessedMessageId) : null;
 
-  // Open the chat so TDLib loads remote messages, then load chat history
-  // from the server. getChat forces TDLib to fetch chat metadata and
-  // getChatHistory with from_message_id=0 triggers a server-side fetch.
-  await invokeWithTimeout(client, {
-    _: "openChat",
-    chat_id: Number(chatId),
-  });
-
-  // Force TDLib to load the full chat list which populates chat state
+  // Open the chat so TDLib can access it
   try {
-    await invokeWithTimeout(client, {
-      _: "getChat",
-      chat_id: Number(chatId),
-    });
+    await invokeWithTimeout(client, { _: "openChat", chat_id: Number(chatId) });
   } catch {
-    // Ignore - chat may already be loaded
+    // Ignore — may already be open
   }
 
-  // Give TDLib time to sync chat data from the server
-  await sleep(2000);
-
-  let currentFromId = 0;
   let totalScanned = 0;
   let pageCount = 0;
 
-  // eslint-disable-next-line no-constant-condition
-  while (true) {
-    if (pageCount >= MAX_SCAN_PAGES) {
-      log.warn(
-        { chatId: chatId.toString(), pageCount, totalScanned },
-        "Hit max page limit for channel scan, stopping"
-      );
-      break;
-    }
-    pageCount++;
+  // Use searchChatMessages with document filter — this works even when
+  // getChatHistory is restricted (e.g. hidden history for new members).
+  // We search for documents first, then photos separately.
+  for (const filter of [
+    { _: "searchMessagesFilterDocument" as const, kind: "document" },
+    { _: "searchMessagesFilterPhoto" as const, kind: "photo" },
+  ]) {
+    let fromMessageId = 0;
 
-    const previousFromId = currentFromId;
+    // eslint-disable-next-line no-constant-condition
+    while (true) {
+      if (pageCount >= MAX_SCAN_PAGES) {
+        log.warn(
+          { chatId: chatId.toString(), pageCount, totalScanned },
+          "Hit max page limit for channel scan, stopping"
+        );
+        break;
+      }
+      pageCount++;
 
-    const result = await invokeWithTimeout<{ messages: TdMessage[] }>(client, {
-      _: "getChatHistory",
-      chat_id: Number(chatId),
-      from_message_id: currentFromId,
-      offset: 0,
-      limit: Math.min(limit, 100),
-      only_local: false,
-    });
+      const result = await invokeWithTimeout<{ messages: TdMessage[]; total_count?: number }>(client, {
+        _: "searchChatMessages",
+        chat_id: Number(chatId),
+        query: "",
+        from_message_id: fromMessageId,
+        offset: 0,
+        limit: Math.min(limit, 100),
+        filter,
+        message_thread_id: 0,
+      });
 
-    if (!result.messages || result.messages.length === 0) break;
+      if (!result.messages || result.messages.length === 0) break;
 
-    totalScanned += result.messages.length;
+      totalScanned += result.messages.length;
 
-    for (const msg of result.messages) {
-      // Check for archive documents
-      const doc = msg.content?.document;
-      if (doc?.file_name && doc.document && isArchiveAttachment(doc.file_name)) {
-        archives.push({
-          id: BigInt(msg.id),
-          fileName: doc.file_name,
-          fileId: String(doc.document.id),
-          fileSize: BigInt(doc.document.size),
-          date: new Date(msg.date * 1000),
-        });
-        continue;
+      for (const msg of result.messages) {
+        // Check for archive documents
+        const doc = msg.content?.document;
+        if (doc?.file_name && doc.document && isArchiveAttachment(doc.file_name)) {
+          // Skip if we've already processed past this message
+          if (boundary && msg.id <= boundary) continue;
+          archives.push({
+            id: BigInt(msg.id),
+            fileName: doc.file_name,
+            fileId: String(doc.document.id),
+            fileSize: BigInt(doc.document.size),
+            date: new Date(msg.date * 1000),
+          });
+          continue;
+        }
+
+        // Check for photo messages (potential previews)
+        const photo = msg.content?.photo;
+        const caption = msg.content?.caption?.text ?? "";
+        if (photo?.sizes && photo.sizes.length > 0) {
+          if (boundary && msg.id <= boundary) continue;
+          const smallest = photo.sizes[0];
+          photos.push({
+            id: BigInt(msg.id),
+            date: new Date(msg.date * 1000),
+            caption,
+            fileId: String(smallest.photo.id),
+            fileSize: smallest.photo.size || smallest.photo.expected_size,
+          });
+        }
       }
 
-      // Check for photo messages (potential previews)
-      const photo = msg.content?.photo;
-      const caption = msg.content?.caption?.text ?? "";
-      if (photo?.sizes && photo.sizes.length > 0) {
-        const smallest = photo.sizes[0];
-        photos.push({
-          id: BigInt(msg.id),
-          date: new Date(msg.date * 1000),
-          caption,
-          fileId: String(smallest.photo.id),
-          fileSize: smallest.photo.size || smallest.photo.expected_size,
-        });
-      }
+      onProgress?.(totalScanned);
+
+      // Advance pagination
+      fromMessageId = result.messages[result.messages.length - 1].id;
+      if (result.messages.length < Math.min(limit, 100)) break;
+
+      await sleep(config.apiDelayMs);
     }
-
-    // Report scanning progress after each page
-    onProgress?.(totalScanned);
-
-    currentFromId = result.messages[result.messages.length - 1].id;
-
-    // Stuck detection: if from_message_id didn't advance, break to prevent infinite loop
-    if (currentFromId === previousFromId) {
-      log.warn(
-        { chatId: chatId.toString(), currentFromId, totalScanned },
-        "Pagination stuck (from_message_id not advancing), breaking"
-      );
-      break;
-    }
-
-    // Stop scanning once we've gone past the boundary (this page is the lookback)
-    if (boundary && currentFromId < boundary) break;
-
-    if (result.messages.length < Math.min(limit, 100)) break;
-
-    // Rate limit delay
-    await sleep(config.apiDelayMs);
   }
 
   // Close the chat after scanning
   await invokeWithTimeout(client, {
     _: "closeChat",
     chat_id: Number(chatId),
-  }).catch(() => {}); // Ignore close errors
+  }).catch(() => {});
 
   log.info(
     { chatId: chatId.toString(), archives: archives.length, photos: photos.length, totalScanned, pages: pageCount },