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RPC workload behavior

Routing guarantees depend on the operation. Classify the workload before choosing a rollout and recovery plan.

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Stateless reads

Methods such as eth_chainId, eth_blockNumber, current balances, transaction receipts, and many contract calls are the cleanest failover candidates. Lasso can try another eligible provider when a failure is safe to retry. Applications must still tolerate ordinary chain reorganization and provider freshness differences.

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Historical state and logs

Historical block, state, and log coverage varies independently across provider plans. Lasso analyzes block references and provider capabilities, but a probe is evidence from selected depths and representative calls—not proof of unlimited history. eth_getLogs also has provider-specific block-range and result-size limits. Split large ranges, paginate with an overlap appropriate for reorg handling, and verify the exact range used by an indexer. A provider that serves old logs may still lack old state, and the reverse is also possible.

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Trace and debug methods

Trace namespaces are often plan-gated or client-specific. Include only providers that support the exact trace method and parameters your application sends. Treat a successful representative probe as a starting point, then test real payload shapes and timeouts.

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Transaction broadcast

eth_sendRawTransaction sends the signed bytes to one selected upstream under one deadline. Lasso does not automatically retry or fan out after dispatch because a lost response may still mean the transaction was applied. Production senders should own signing, nonce allocation, idempotency, reconciliation by transaction hash, rebroadcast policy, and receipt/finality tracking.

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Stateful HTTP filters

Lasso currently rejects eth_newFilter, eth_newBlockFilter, eth_newPendingTransactionFilter, eth_getFilterChanges, eth_getFilterLogs, and eth_uninstallFilter locally with -32601. Their IDs are provider-local, and Lasso does not yet have an accepted affinity lifecycle for creation, follow-up calls, owner loss, and expiry. Use eth_getLogs for historical scans and WebSocket subscriptions for real-time delivery.

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WebSocket subscriptions

Lasso multiplexes compatible upstream subscriptions and can fail over within a profile. On provider changes it can gap-fill newHeads and log subscriptions with bounded HTTP backfill and duplicate suppression. The launch subset accepts only newHeads and logs; pending-transaction subscriptions are not included. Recovery that exceeds its time, replay, buffer, or ancestry bounds closes the affected client explicitly. Lasso does not continue after a silent partial backfill. Within-profile subscription failover should not be confused with system-profile HTTP fallback. Cross-profile subscription fallback is not part of the current guarantee. Clients must reconnect after network interruption, handle duplicate or delayed events, and keep their own durable checkpoint for indexer-grade processing.