LTMigrator

LTMigrator.vy — upgrade path without forcing users to withdraw.

Constants / Immutables

Name	Notes
`STABLECOIN`	crvUSD
`FACTORY_OWNER`	MFOwner — validates LTs are factory-issued

Signature	Purpose
`preview_migrate_plain(lt_from, lt_to, shares_in, debt_coefficient) → shares_out`	View — unstaked path
`preview_migrate_staked(lt_from, lt_to, shares_in, debt_coefficient) → shares_out`	View — staked path
`migrate_plain(lt_from, lt_to, shares_in, min_out, debt_coefficient)`	Execute unstaked migration
`migrate_staked(lt_from, lt_to, shares_in, min_out, debt_coefficient)`	Execute staked migration

debt_coefficient default 1e18. Scale down (e.g. 0.9e18) to migrate with reduced leverage.

String	Cause
`lt_to deprecated`	Target LT has been disabled in the factory owner (`disabled_lts[lt_to] == True`). The DAO sets this when winding a market down via `lt_allocate_stablecoins(lt, 0)`. Migrate to a different LT.
`not enough out`	`shares_out < min_out` in staked migration

Validate both LTs belong to a factory (via FACTORY_OWNER.lt_in_factory()) and that the target is not disabled (disabled_lts[lt_to] == False).
collect_fees() on source AMM (so fee accruals do not contaminate measurements).
lt_from.withdraw(shares_in, 0) → receive asset + debt unwound through Cryptoswap.
Temporarily inflate target's stablecoin_allocation to max((pool_value + additional_crvusd) × 2.2, previous_allocation) on target LT — gives the deposit headroom against the AMM.max_debt() / 2 cap.
lt_to.deposit(assets, debt × debt_coefficient / 1e18, min_out, receiver) into target.
Restore allocation to its previous value.
For staked: unstake from source gauge before, re-stake into target gauge after.