bug: eth_getLogs on rpc.testnet.arc.network times out / fails silently for wide block ranges, breaking indexers and dApp analytics

[osr21]

https://rpc.testnet.arc.network does not return results for eth_getLogs requests spanning the full chain (current head ~43.3M blocks). Requests hang past 60s and never return, with no limit exceeded style error.

Reproduce (ethers v6):

const p = new ethers.JsonRpcProvider('https://rpc.testnet.arc.network');
// any deployed contract, e.g. our LendingPool 0x4dc7A9BbcB1139cDeDf5274272F541461ef4d20E
await p.getLogs({
  address: '0x4dc7A9BbcB1139cDeDf5274272F541461ef4d20E',
  topics: [ethers.id('Supply(address,address,uint256)')],
  fromBlock: 0,
  toBlock: 'latest',
});   // → hangs > 60s, never resolves

Workarounds we had to use:

• Chunking to ≤10k blocks — still 4000+ sequential requests to scan history; impractical from a browser
• Falling back to the Arcscan v2 REST API to list contract activity

Impact:

• Subgraph/indexer cold-starts require scanning from deploy block — currently not viable against the public RPC
• Any dApp showing historical events (liquidations feed, position history, leaderboards) can't use the public RPC directly
• useLogs-style React hooks degrade to "mock data" fallbacks

Asks:

1. Document the actual eth_getLogs block-range and result-size limits in the RPC docs — currently unstated
2. Return a clear error (e.g. -32005 limit exceeded) instead of timing out so clients can chunk automatically
3. Consider raising the limit, or recommend a partner archive node / subgraph endpoint for indexing workloads

Discovered while building ArcLend.

[osr21]

Safe batch size confirmed: 10,000 blocks per request

After testing, batching at 10,000 blocks reliably returns without timeout.

async function getAllLogs(provider: ethers.Provider, filter: ethers.Filter) {
  const latest = await provider.getBlockNumber();
  const BATCH  = 10_000;
  const logs: ethers.Log[] = [];

  for (let from = 0; from <= latest; from += BATCH) {
    const chunk = await provider.getLogs({
      ...filter,
      fromBlock: from,
      toBlock:   Math.min(from + BATCH - 1, latest),
    });
    logs.push(...chunk);
  }
  return logs;
}

Note: Arc Testnet is currently at ~43 M+ blocks, so iterating from block 0 takes ~4,300 batches. For most practical use cases, it's better to start from a known deployment block rather than from 0.