Module cutover 

Legacy → new-protocol cutover machinery.

Three concerns live here:

• extract_pre_cutover_seed walks a live legacy SystemContextHandle and produces a PreCutoverSeed.
• CutoverGate latches once legacy has crossed into the new version, extracts the seed, and dispatches it into the new coordinator.
• forward_legacy_timeout_votes and forward_legacy_epoch_changes tail the legacy event stream and bridge those events into the coordinator’s client API so the new protocol can form TC2s and refresh its peer set at epoch boundaries.

Structs

CutoverGate

Latches once legacy crosses into the new protocol. The single API production and tests share: poll check on every coordinator loop iteration; once it returns true the cutover has happened and subsequent calls short-circuit.

Functions

extract_pre_cutover_seed

Walk legacy state to produce a PreCutoverSeed; None on a broken walk.

forward_legacy_epoch_changes

Forward legacy epoch transitions into bump_network_epoch. epoch_height == 0 disables forwarding.

forward_legacy_timeout_votes

Forward legacy TimeoutVote2 events into the new-protocol timeout collectors so the first new leader can form TC2 at the boundary.