fix: skip finalization advance for stale finalized sources#802
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latifkasuli wants to merge 1 commit into
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fix: skip finalization advance for stale finalized sources#802latifkasuli wants to merge 1 commit into
latifkasuli wants to merge 1 commit into
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Summary
This fixes an Lstar finalization edge case where an attestation with a source checkpoint at or behind the current finalized boundary could justify a newer target, then incorrectly enter the finalization-advance scan from below the finalized boundary.
Finalized sources are valid justification anchors:
JustifiedSlots.is_slot_justified()treats slots at or belowlatest_finalized.slotas already justified. But once such an attestation crossed the supermajority threshold, the finalization logic scannedsource.slot + 1 .. target.slotand calledSlot.is_justifiable_after(finalized_slot)on candidate slots beforefinalized_slot, triggeringCandidate slot must not be before finalized slot.The fix gates finalization advancement on
source.slot > finalized_slot. Stale finalized sources may still justify newer targets, but they no longer try to rewind or scan below the finalized boundary.Validation
uv run --group test fill tests/consensus/lstar/state_transition/test_finalization.py --fork=Lstar --clean -quv run --group lint ruff check src/lean_spec/forks/lstar/spec.py tests/consensus/lstar/state_transition/test_finalization.pyuv run --group lint ruff format --check src/lean_spec/forks/lstar/spec.py tests/consensus/lstar/state_transition/test_finalization.py