Synthetic Transactions on Sei

Sei supports synthetic transactions—Cosmos-originated operations that are wrapped and surfaced through the EVM RPC layer. These include association flows, governance events, and distribution payouts. This guide explains how they appear through JSON-RPC and how to index them correctly after v6.1.11.

Key Properties

Definition	Cosmos-originated transactions emitted through the EVM log interface (associations, governance, distribution).
Flag	`synthetic: true` in log metadata (`v6.1.11`).
Gas accounting	Excluded from block/receipt `gasUsed`; costs settle in the Cosmos ante handler.
Association method	`sei_associate` handles signature-based link between Sei and EVM addresses.
Indexing	Use the `sei_` namespace to stream synthetic logs alongside EVM logs.

Association Flow (`sei_associate`)


{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "sei_associate",
  "params": [
    {
      "custom_message": "Link my account",
      "r": "0x...",
      "s": "0x...",
      "v": "0x1c"
    }
  ]
}

Sends a synthetic transaction without gas fees; verification happens in the Cosmos ante handler.
Resulting logs appear under sei_seiAssociation with synthetic: true.
Indexers should persist the association tuple (seiAddress, evmAddress) and treat the event as finalized once included in a block.

Indexing Strategy

Dual namespace polling

Query both eth_getLogs and sei_getLogs (or sei_subscribe) to capture synthetic envelopes alongside EVM events.

Synthetic segregation

Store synthetic logs in a dedicated table keyed by {tx_hash, module} for downstream reconciliation.

Cosmos cross-reference

If enrichment is needed, join against module-specific gRPC queries (e.g., distribution rewards) using the event payload.

Interaction With Gas Accounting

Synthetic envelopes do not alter receipt gasUsed (see rpc-gas-accounting).
When computing block-level gas metrics, exclude synthetic logs entirely; they are informational signals only.
Estimating gas for synthetic flows is unnecessary—sei_associate and similar methods are processed outside the EVM gas model.

Troubleshooting

Error	Cause	Fix
`Missing synthetic flag`	Node running pre-`v6.1.11` binary.	Upgrade to `v6.1.11` or later; the flag is added at log emission time.
`Association not visible via eth_getLogs`	Querying `eth_` namespace only.	Switch to `sei_getLogs` or include the `sei_` namespace to fetch synthetic events.
`Duplicate association events`	Client resubmitted association payload.	Treat the first inclusion as canonical; later duplicates can be ignored.