Gloas payload cache

[dknopik]

Issue Addressed

In Gloas, beacon blocks are imported into fork choice immediately - the payload envelope and data columns arrive
separately. KZG commitments moved from the column sidecar into the execution payload bid, so the existing
DataAvailabilityChecker (which assumes block and data are coupled) can't be used for Gloas.

Proposed Changes

• Introduced PendingPayloadCache to keep track of payload and data columns per block root.
• Added gossip column verification
• Added support for Gloas data column reconstruction
• Payload envelope verification simplified: removed MaybeAvailableEnvelope, ExecutedEnvelope, EnvelopeImportData

Not yet implemented (tracked with TODOs):

• Proper lookup sync for Gloas columns arriving before blocks
• Partial column merging for Gloas
• Moving load_gloas_payload_bid disk reads off the async runtime
• Backfill/range sync for Gloas

Based on @eserilev's PR and work in progress. See also #9202 for verification.

[mergify]

Some required checks have failed. Could you please take a look @dknopik? 🙏

[jimmygchen]

Thanks for addressing the comments @eserilev

I've fixed the conflicts with unstable and also reverted the commit "PriorKnownUnpublished should still propagate columns" *(973590a) to fix CI as it caused a regression.

GossipDataColumnError::PriorKnownUnpublished occurs when we have blobs from the EL, but have not publish some of the columns due to gradual column publication
- they are scheduled to be published in the background, and we don't want to re-process them again hence we want to return None during block publishing.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-05-13 06:34 UTC · Rule: default
• ✅ Checks passed · on draft merge queue: embarking unstable (9101ddc) and #9209 together #9300
• ✅ Merged — 2026-05-13 07:03 UTC · at e879090085712e846b6e0040016a439afd1eff64 · squash

This pull request spent 29 minutes 21 seconds in the queue, including 27 minutes 27 seconds running CI.

Required conditions to merge

• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • Gloas payload cache #9209
• #changes-requested-reviews-by = 0 [🛡 GitHub branch protection]
  • Gloas payload cache #9209
• check-success=local-testnet-success
• check-success=test-suite-success