> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lasso.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# RPC routing for indexers and historical backfills

> Test historical state and eth_getLogs through your actual EVM RPC route before moving an indexer or backfill behind Lasso Cloud.

**Lasso Cloud · For indexer operators.** Route historical EVM reads through a
profile of configured providers, then qualify the exact blocks and methods your
indexer needs. A provider serving an old block header may still lack old state
or logs at that block.

## Match the provider to the query

Lasso considers declared and probed history evidence when admitting a request.
Selected depths do not prove unlimited archive coverage. Historical state,
receipts, and logs have different coverage; `eth_getLogs` also faces
provider-specific block-range and result-size limits. See
[RPC workload behavior](/cloud/rpc-behavior#historical-state-and-logs) for the
method boundary.

Build a small set of known positive queries from your own contracts and chain
history. Keep the expected block hash, nonempty log or receipt identity, and
expected state value. Run each query against the direct provider and the exact
Lasso endpoint and credential your indexer will use. An empty response is not
proof that the provider covered the requested history.

| Indexer task           | Trial query                                       | Check                                              |
| ---------------------- | ------------------------------------------------- | -------------------------------------------------- |
| Rebuild state          | `eth_call` or a state method at a known old block | Expected value and block selector support          |
| Scan events            | `eth_getLogs` over a representative range         | Complete known logs, range limits, and result size |
| Reconcile transactions | `eth_getTransactionReceipt` for known hashes      | Receipt identity and expected block                |

Split large log ranges to fit the upstreams you use. Keep a durable checkpoint
and a reorg overlap in your indexer, then deduplicate by log identity. Test the
same path from your deployment regions and under representative request volume.

## Inspect routing during a backfill

The [dashboard](https://lasso.sh/dashboard) shows current provider health and
recent routing activity. Opt-in [`lasso_meta`](/cloud/observability#opt-in-metadata)
can identify the executing upstream when that field is available. Preserve the
request ID and the query's block selector alongside your result. For HTTP
batches, items route independently; a batch is neither pinned to one provider
nor an atomic snapshot. Use [one block hash for related state reads](/cloud/read-at-one-block)
when you need them to refer to the same block.

Lasso's [dated historical qualification](/cloud/historical-workloads) shows
positive samples and gaps across selected chains, depths, and methods. It is a
model for testing, not a coverage promise for your contracts or a later
deployment. Retain your previous endpoint until the Lasso route passes your
own correctness, latency, and failure trials.