Gloas consensus logic for attestations

[michaelsproul]

Update attestation consensus logic for the Gloas fork.

This covers get_attestation_participation_flag_indices and process_attestation at the spec level. Inside LH we have split process_attestation into several parts for use in different places, so we update those component functions:

• verify_attestation_for_state covers the new check on the attestation data index. This function is called from verify_attestation_for_block_inclusion which is otherwise the same (no other changes in Gloas compared to Electra).
• A new variant of process_attestation{s} is added covering the Gloas case. It would have been possible to abstract the existing Electra logic, but with this logic already being quite gnarly I can see the case for a separate function (this is how Shane had it set up on his branch). I've made some tweaks so that it follows the flow of the spec , although there are few places where differences are required due to Rust's ownership/borrowing.

Many credits to @shane-moore for writing this logic. I just adapted and reviewed it.

Additional Info

All EF tests for attestations are passing 🎉

Co-authored-by: Shane K Moore <41407272+shane-moore@users.noreply.github.com>

[jimmygchen]

This looks great, I've got nothing to add. Let's merge 👍

[mergify]

Merge Queue Status

🟠 Waiting for merge conditions (rule: default)

Entered the queue at: 2026-02-09 04:54 UTC.
Checks are running on draft #8774 (dashboard).
Merge ETA: 2026-02-09 05:26 UTC. Buckle up 🚀

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