Tighten block transaction drilldown paging

frontend/src/pages/blocks/[number].tsx

@@ -21,6 +21,8 @@ export default function BlockDetailPage() {
   const [blockTransactions, setBlockTransactions] = useState<Transaction[]>([])
   const [loading, setLoading] = useState(true)
   const [transactionsLoading, setTransactionsLoading] = useState(true)
+  const [transactionsError, setTransactionsError] = useState(false)
+  const [hasNextTransactionsPage, setHasNextTransactionsPage] = useState(false)
   const [transactionPage, setTransactionPage] = useState(1)
   const blockTransactionPageSize = 25
 
@@ -39,12 +41,17 @@ export default function BlockDetailPage() {
 
   const loadBlockTransactions = useCallback(async () => {
     setTransactionsLoading(true)
+    setTransactionsError(false)
     try {
-      const { ok, data } = await transactionsApi.listByBlockSafe(chainId, blockNumber, transactionPage, blockTransactionPageSize)
-      setBlockTransactions(ok ? data : [])
+      const { ok, data, hasNextPage } = await transactionsApi.listByBlockSafe(chainId, blockNumber, transactionPage, blockTransactionPageSize)
+      setBlockTransactions(data)
+      setHasNextTransactionsPage(hasNextPage)
+      setTransactionsError(!ok)
     } catch (error) {
       console.error('Failed to load block transactions:', error)
       setBlockTransactions([])
+      setHasNextTransactionsPage(false)
+      setTransactionsError(true)
     } finally {
       setTransactionsLoading(false)
     }
@@ -57,6 +64,8 @@ export default function BlockDetailPage() {
     if (!isValidBlock) {
       setLoading(false)
       setTransactionsLoading(false)
+      setTransactionsError(false)
+      setHasNextTransactionsPage(false)
       setBlock(null)
       setBlockTransactions([])
       return
@@ -81,8 +90,6 @@ export default function BlockDetailPage() {
   const gasUtilization = block && block.gas_limit > 0
     ? Math.round((block.gas_used / block.gas_limit) * 100)
     : null
-  const canGoNextTransactionsPage = blockTransactions.length === blockTransactionPageSize
-
   const transactionColumns = [
     {
       header: 'Hash',
@@ -232,7 +239,9 @@ export default function BlockDetailPage() {
                   columns={transactionColumns}
                   data={blockTransactions}
                   emptyMessage={
-                    block.transaction_count > 0
+                    transactionsError
+                      ? 'Unable to load indexed block transactions right now. Please retry from this page in a moment.'
+                      : block.transaction_count > 0
                       ? 'No indexed block transactions were returned for this page yet.'
                       : 'This block does not contain any indexed transactions.'
                   }
@@ -255,7 +264,7 @@ export default function BlockDetailPage() {
                       <button
                         type="button"
                         onClick={() => setTransactionPage((current) => current + 1)}
-                        disabled={transactionsLoading || !canGoNextTransactionsPage}
+                        disabled={transactionsLoading || !hasNextTransactionsPage}
                         className="rounded bg-gray-200 px-4 py-2 text-gray-900 disabled:cursor-not-allowed disabled:opacity-50 dark:bg-gray-800 dark:text-gray-100"
                       >
                         Next tx page

frontend/src/services/api/transactions.test.ts

@@ -27,6 +27,7 @@ describe('transactionsApi.listByBlockSafe', () => {
             timestamp: '2026-04-16T09:40:12.000000Z',
           },
         ],
+        next_page_params: { page: 2, page_size: 10 },
       }),
     })
 
@@ -36,12 +37,25 @@ describe('transactionsApi.listByBlockSafe', () => {
 
     expect(result.ok).toBe(true)
     expect(result.data).toHaveLength(1)
+    expect(result.hasNextPage).toBe(true)
     expect(result.data[0]?.hash).toBe('0xabc')
     expect(fetchMock).toHaveBeenCalledTimes(1)
     expect(fetchMock.mock.calls[0]?.[0]).toEqual(
       expect.stringContaining('/api/v2/blocks/123/transactions?page=1&page_size=10'),
     )
   })
+
+  it('returns a non-throwing failure result when the block transaction request fails', async () => {
+    vi.stubGlobal('fetch', vi.fn().mockRejectedValue(new Error('network down')))
+
+    const result = await transactionsApi.listByBlockSafe(138, 123, 1, 10)
+
+    expect(result).toEqual({
+      ok: false,
+      data: [],
+      hasNextPage: false,
+    })
+  })
 })
 
 describe('transactionsApi.diagnoseMissing', () => {

frontend/src/services/api/transactions.ts

@@ -76,6 +76,11 @@ export interface TransactionLookupDiagnostic {
   rpc_url?: string
 }
 
+export interface BlockTransactionListPage {
+  data: Transaction[]
+  next_page_params: Record<string, unknown> | null
+}
+
 const CHAIN_138_PUBLIC_RPC_URL = 'https://rpc-http-pub.d-bis.org'
 
 function resolvePublicRpcUrl(chainId: number): string | null {
@@ -227,26 +232,37 @@ export const transactionsApi = {
       return { ok: false, data: [] }
     }
   },
-  listByBlock: async (chainId: number, blockNumber: number, page = 1, pageSize = 25): Promise<ApiResponse<Transaction[]>> => {
+  listByBlock: async (chainId: number, blockNumber: number, page = 1, pageSize = 25): Promise<ApiResponse<BlockTransactionListPage>> => {
     const params = new URLSearchParams({
       page: page.toString(),
       page_size: pageSize.toString(),
     })
-    const raw = await fetchBlockscoutJson<{ items?: unknown[] }>(`/api/v2/blocks/${blockNumber}/transactions?${params.toString()}`)
+    const raw = await fetchBlockscoutJson<{ items?: unknown[]; next_page_params?: Record<string, unknown> | null }>(
+      `/api/v2/blocks/${blockNumber}/transactions?${params.toString()}`
+    )
     const data = Array.isArray(raw?.items) ? raw.items.map((item) => normalizeTransaction(item as never, chainId)) : []
-    return { data }
+    return {
+      data: {
+        data,
+        next_page_params: raw?.next_page_params ?? null,
+      },
+    }
   },
   listByBlockSafe: async (
     chainId: number,
     blockNumber: number,
     page = 1,
     pageSize = 25,
-  ): Promise<{ ok: boolean; data: Transaction[] }> => {
+  ): Promise<{ ok: boolean; data: Transaction[]; hasNextPage: boolean }> => {
     try {
       const { data } = await transactionsApi.listByBlock(chainId, blockNumber, page, pageSize)
-      return { ok: true, data }
+      return {
+        ok: true,
+        data: data.data,
+        hasNextPage: data.next_page_params != null,
+      }
     } catch {
-      return { ok: false, data: [] }
+      return { ok: false, data: [], hasNextPage: false }
     }
   },
 }