Feature request: add support for anonymous events with 4 indexed parameters

[iceanddust]

Summary

Envio does not currently support indexing anonymous Solidity events that use all 4 topic slots for indexed parameters. Since anonymous events don't emit the event signature as topic0, they can use all 4 topic slots for indexed data — but Envio's codegen assumes topic0 is always the event selector and only supports up to 3 indexed parameters.

Current Behavior

• Adding indexed to all 4 parameters in config.yaml causes codegen to fail because LogSelection.parseEventFiltersOrThrow only supports up to ~topic3.
• Removing indexed from the event definitions allows codegen to pass, but the indexer cannot match the events on-chain since the topic layout doesn't match.
• The generated code in Types.res.js sets "anonymous": false in the ABI and uses a sighash for topic0 filtering, neither of which apply to anonymous events.

Expected Behavior

Envio should support anonymous events by:

1. Allowing 4 indexed parameters in event definitions (since topic0 is not used for the event selector)
2. Setting "anonymous": true in the generated ABI
3. Skipping sighash/topic0 filtering for anonymous events

Testing steps

You can test the indexing of an annonymous event by using this contract:

• Chain ID: Mainnet
• Contract name: LockstakeMigrator
• Contract address: 0x473d777f608C3C24B441AB6bD4bBcA6b7F9AF90B
• Event:

event Migrate(
    address indexed oldUrn,
    address indexed newUrn,
    address indexed caller,
    uint256 indexed ink
) anonymous;

[DZakh]

Hi, thanks for the very detailed issue. It'll be very useful for implementation. Unfortunately after I've done a research spike, the change required is quite big, and won't be included to our roadmap until we finish v3.

[iceanddust]

Hey! That is actually fine since my team and I found a workaround for these events, and we won't need to add them to the Envio indexer for the time being :)