fix: mail grouping loads all mails at once with large page_size, no infinite scroll during grouping

frontend/src/api/mail.ts

@@ -487,10 +487,11 @@ export function syncFolder(folderId: string): Promise<{ synced: number; error?:
 
 // ─── Mails ──────────────────────────────────────────────────────────────────
 
-export function fetchMails(folderId: string, page: number, sortBy?: string, sortOrder?: string): Promise<MailListResult> {
+export function fetchMails(folderId: string, page: number, sortBy?: string, sortOrder?: string, pageSize?: number): Promise<MailListResult> {
   const params = new URLSearchParams({ folder_id: folderId, page: String(page) });
   if (sortBy) params.set('sort_by', sortBy);
   if (sortOrder) params.set('sort_order', sortOrder);
+  if (pageSize) params.set('page_size', String(pageSize));
   return apiGet<MailListResult>(`/mail?${params.toString()}`);
 }
 

frontend/src/pages/Mail.tsx

@@ -193,11 +193,14 @@ export function MailPage() {
           setMailsTotal(result.total);
         }
       } else {
-        const result = await fetchMails(currentFolderId, mailsPage, sortBy, sortOrder);
+        // When grouping is active, load all mails at once (no pagination)
+        const isGrouping = mailGroupState.conditions.length > 0;
+        const pageToLoad = isGrouping ? 1 : mailsPage;
+        const result = await fetchMails(currentFolderId, pageToLoad, sortBy, sortOrder, isGrouping ? 10000 : undefined);
         // Only update if still on the same folder
         if (selectedFolderIdRef.current === currentFolderId) {
-          // Append for infinite scroll (page > 1), replace on page 1 or folder change
+          // Append for infinite scroll (page > 1), replace on page 1 or folder change or grouping
-          setMails(mailsPage > 1 ? (prev) => [...prev, ...result.mails] : result.mails);
+          setMails(!isGrouping && mailsPage > 1 ? (prev) => [...prev, ...result.mails] : result.mails);
           setMailsTotal(result.total);
         }
       }
@@ -209,7 +212,7 @@ export function MailPage() {
       }
     }
     setLoadingMails(false);
-  }, [selectedFolderId, mailsPage, searchQuery, sortBy, sortOrder]);
+  }, [selectedFolderId, mailsPage, searchQuery, sortBy, sortOrder, mailGroupState]);
 
   useEffect(() => {
     loadMails();
@@ -908,7 +911,7 @@ export function MailPage() {
                 setMailsPage((p) => p + 1);
               }
             }}
-            hasMore={mails.length < mailsTotal}
+            hasMore={mailGroupState.conditions.length === 0 && mails.length < mailsTotal}
           />
         </ResizablePanel>
 
@@ -979,7 +982,7 @@ export function MailPage() {
                   setMailsPage((p) => p + 1);
                 }
               }}
-              hasMore={mails.length < mailsTotal}
+              hasMore={mailGroupState.conditions.length === 0 && mails.length < mailsTotal}
             />
           </div>
         )}