Let exits use consolidation queue (EIP-8080)

[barnabasbusa]

Summary

Implements EIP-8080 ("Let exits use the consolidation queue") at the Gloas fork.

Spec change

Single function override in specs/gloas/beacon-chain.md — Modified compute_exit_epoch_and_update_churn. Adds a routing prefix that checks whether the exit queue has grown longer than the consolidation queue; if so, the exit is satisfied through compute_consolidation_epoch_and_update_churn with exit_balance converted by the 2/3 factor that reflects the relative weak-subjectivity weight of exit vs. consolidation churn.

Intro bullet list updated to reference EIP-8080.

No new constants, no new state fields, no fork transition logic.

Composition with EIP-8061 (#5061)

This PR is written against current master, so the inner churn-limit call in the preserved tail of compute_exit_epoch_and_update_churn is still get_activation_exit_churn_limit(state) (the Electra form). If #5061 lands first, this PR needs a one-line update in the same function to switch to get_exit_churn_limit(state) — mechanical rebase, no semantic change.

The EIP-8080 addition and the EIP-8061 rewrite are orthogonal: 8080 adds a routing prefix, 8061 changes the churn-limit accessor in the tail. They compose cleanly regardless of merge order.

Design notes

• The comparison uses the adjusted earliest_exit_epoch / earliest_consolidation_epoch (both max()-clamped to activation_exit_epoch), matching the "full function" form in the EIP and the correction in ethereum/EIPs#10883.
• The Gwei(2 * exit_balance // 3) wrap is required by the mypy type check (the Gwei typed constant is not auto-coerced from the divided int).
• Weak-subjectivity budget is unchanged — one unit of exit churn corresponds to 2/3 of a unit of consolidation churn, so the total weak-subjectivity impact is preserved whether consolidation churn is spent on consolidations or on rerouted exits.

Tests

Six unit tests under tests/core/pyspec/eth_consensus_specs/test/gloas/unittests/test_compute_exit_epoch_and_update_churn.py:

• No routing when exit and consolidation queues are equal length
• No routing when consolidation queue is longer than exit queue
• Routes through consolidation queue when exit queue is longer
• 2/3 conversion factor applied to exit_balance when routed
• One-epoch difference is enough to trigger routing (edge case)
• Exit-queue state fields (earliest_exit_epoch, exit_balance_to_consume) are preserved across a routing call

Local verification: make lint clean, all 6 tests pass on the minimal preset.

Test plan

• CI passes on all presets
• Rebase onto Add EIP-8061 churn adjustment tests and config #5061 (or vice versa) once either PR lands and sync the per_epoch_churn accessor accordingly
• Cross-client review, especially around the interaction with earliest_consolidation_epoch bookkeeping when exits and consolidations arrive in the same block

Related

• EIP text: https://eips.ethereum.org/EIPS/eip-8080
• EIP spec-inconsistency fix: Update EIP-8080: Fix specification inconsistency in compute_exit_epoc… EIPs#10883
• EIP test-case additions: Update EIP-8080: Add test cases for EIP-8080 EIPs#11290
• Composes with Add EIP-8061 churn adjustment tests and config #5061 (EIP-8061: increase exit and consolidation churn)