> ## Documentation Index > Fetch the complete documentation index at: https://xoxno.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Stellar lending Blend migration > Atomically repay Blend debt, withdraw collateral and supply, and open an equivalent XOXNO position in one transaction. `migrate_from_blend` moves a Blend V2 position to XOXNO in one transaction. The controller repays Blend debt, withdraws collateral and non-collateral supply, deposits the withdrawn assets as XOXNO collateral, and runs a final health check before persisting state. ## Entrypoint ```rust theme={"system"} migrate_from_blend( caller: Address, account_id: u64, // 0 creates a new account spoke_id: u32, hub_id: u32, blend_pool: Address, // must be governance-approved collateral_assets: Vec
, // WithdrawCollateral, sweep-all supply_assets: Vec
, // Withdraw (non-collateral supply), sweep-all debt_caps: Vec<(Address, i128)>, // (debt_asset, max_repay_cap) ) -> u64 ``` | Parameter | Semantics | | ------------------- | -------------------------------------------------------------------------------------------------------------- | | `caller` | Must authorize the call. Owns the Blend position and the resulting XOXNO account. | | `account_id` | `0` creates a fresh account; non-zero merges into an existing account owned by `caller`. | | `blend_pool` | Target Blend pool. Must pass `is_blend_pool_approved` or the call reverts with `#42 BlendPoolNotApproved`. | | `collateral_assets` | Blend collateral tokens to withdraw. Each uses `WithdrawCollateral` with `i128::MAX` internally. | | `supply_assets` | Blend non-collateral supply to withdraw. Each uses `Withdraw` with `i128::MAX`. Deposited as XOXNO collateral. | | `debt_caps` | Per debt asset, the maximum the controller may borrow to repay Blend. Must be ≥ actual Blend debt. | At least one of `{collateral_assets, supply_assets, debt_caps}` must be non-empty. ## Atomic flow ```mermaid theme={"system"} flowchart TD A["migrate_from_blend"] --> B{"debt_caps empty?"} B -->|no| C["Phase 1: repay"] B -->|yes| D{"collateral or supply?"} C --> C1["Snapshot controller balances"] C1 --> C2["open_migration_borrow per debt (fee=0)"] C2 --> C3["Authorize transfer controller → blend_pool"] C3 --> C4["Blend submit: Repay per debt"] C4 --> C5["Reconcile Blend refunds → exact debt"] C5 --> D D -->|yes| E["Phase 2: withdraw"] D -->|no| F["strategy_finalize"] E --> E1["Fresh snapshot for withdraw assets"] E1 --> E2["Blend submit: WithdrawCollateral + Withdraw"] E2 --> E3["Deposit withdrawn tokens as XOXNO collateral"] E3 --> F F --> G["Health factor / LTV / min-collateral check"] G --> H["Emit BlendMigrationEvent"] ``` The entire flow runs inside one controller call. Any revert rolls back all Blend and XOXNO state changes. ## Debt sourcing Migration does not use the flash-loan receiver pattern. It uses an internal zero-fee strategy borrow: | Mechanism | `flash_loan` | Migration borrow | | ----------------- | ------------------------------------- | --------------------------------------------------- | | Entrypoint | `controller.flash_loan` | `open_migration_borrow` inside `migrate_from_blend` | | Pool call | `pool.flash_loan` → receiver callback | `pool.create_strategy` | | Fee | Configured bps | 0 | | Debt outcome | Repaid in same callback | Permanent debt on the migrated account | | Receiver contract | Required | None | | Solvency check | At callback end | At `strategy_finalize` | ## Refund reconciliation `debt_caps` are upper bounds, not exact debt amounts. When Blend repays less than the cap, Blend refunds the surplus to the controller. `reconcile_debt_refunds` detects the refund via balance delta and calls `repay_debt_from_controller`. The migrated XOXNO debt equals the actual Blend debt, not the cap. ## Looped positions When the same token is both collateral and debt (for example USDC collateral plus USDC debt), the controller uses a two-phase submit: 1. **Phase 1** — repay debt with an isolated balance snapshot so refunds do not alias with withdrawals. 2. **Phase 2** — withdraw collateral and supply with a fresh snapshot. The same asset may appear in both `collateral_assets` and `debt_caps`. Duplicate debt entries in `debt_caps` revert with `#AssetsAreTheSame`. ## Blend request types | Request | Constant | Amount | Purpose | | ------------------ | ----------------------------- | ---------------------- | --------------------------- | | Repay | `REQ_REPAY = 5` | `cap` from `debt_caps` | Clear Blend debt | | WithdrawCollateral | `REQ_WITHDRAW_COLLATERAL = 3` | `i128::MAX` | Sweep all collateral | | Withdraw | `REQ_WITHDRAW = 1` | `i128::MAX` | Sweep non-collateral supply | Non-collateral Blend supply becomes collateral on XOXNO. XOXNO has no non-collateral supply concept. ## Authorization | Leg | Who authorizes | | ---------------------------------------- | -------------------------------------------------------------- | | `migrate_from_blend` | `caller.require_auth()` | | Blend `submit(from=caller)` | Caller in the transaction auth tree (per phase) | | `transfer(controller → blend_pool, cap)` | Controller `authorize_as_current_contract` before repay submit | ## Reentry guard `guarded_submit` sets `FlashLoanOngoing` during Blend calls. Mutating controller entrypoints reject reentry while the guard is set (`#400 FlashLoanOngoing`). ## Governance Blend pools are allow-listed through governance: ```bash theme={"system"} # Schedule via governance (production): propose_approve_blend_pool(proposer, blend_pool_address, salt) # → execute after timelock ``` Approved pools are listed in `configs/blend_pools.json`. Query approval with `is_blend_pool_approved(blend_pool)`. ## Events ```rust theme={"system"} BlendMigrationEvent { topics: ["strategy", "blend_migration"], account_id, blend_pool, collateral_count, supply_count, debt_count, } ``` ## Failure modes | Condition | Error | | ----------------------------------------------------------- | ------------------------------------------- | | Empty `collateral_assets`, `supply_assets`, and `debt_caps` | `#InvalidPayments` | | Unapproved `blend_pool` | `#42 BlendPoolNotApproved` | | Duplicate debt asset in `debt_caps` | `#AssetsAreTheSame` | | `debt_cap` below actual Blend debt | Blend health check revert (atomic rollback) | | End state fails health / LTV / min collateral | `#InsufficientCollateral` at finalize | | Caller does not own target account | Ownership mismatch | ## Example invoke ```bash theme={"system"} stellar contract invoke --id --network \ --source \ -- migrate_from_blend \ --caller \ --account-id 0 \ --spoke-id 1 \ --hub-id 1 \ --blend-pool \ --collateral-assets '[]' \ --supply-assets '[]' \ --debt-caps '[["", "1000000000"]]' ``` Set each `debt_cap` to at least the actual Blend debt for that asset. Use `get_account_positions` and Blend views to size caps before invoking. ## Next Multiply, swap debt, swap collateral, and repay-with-collateral flows. The flash-loan receiver pattern — distinct from migration's zero-fee borrow. Account model, health factor, and spoke constraints after migration. Full `migrate_from_blend` signature and related admin entrypoints.