DA-02 · LESSON 07

UNIT state versus vault state

KEY DEFINITIONS

Terms used in this lesson

UNIT: Ducat’s dollar-pegged stablecoin, the asset a borrower can create against bitcoin collateral.
Vault: A set of Bitcoin outputs and spending rules that holds collateral and represents the current loan state.
Runes: A Bitcoin metaprotocol that assigns fungible-token meaning to transaction outputs through off-chain interpretation.
UTXO: Unspent transaction output: one discrete chunk of bitcoin that can be used as a transaction input.
Collateral: An asset pledged against a debt; it can be used to cover the debt if agreed conditions are breached.
Validator: Software or a participant that independently checks state transitions under a system's rules. The exact role depends on the protocol being discussed.
BTC: The common market ticker for bitcoin.
Outpoint: A transaction ID plus output number that identifies one exact prior output.

Rune token allocations, vault UTXOs, collateral values, and debt records are related protocol views but are not one interchangeable state object.

55 min Difficulty 4/5 Not started

VISUAL MODEL

See the whole mechanism before going step by step

Use the diagrams to orient yourself. Then the guided explanation below teaches every part in depth.

4 explanatory views

CONCEPT-SPECIFIC MAP · ducat vaultA Ducat action moves one Bitcoin-anchored vault state to a successorSelect any state to inspect its exact role.

RELATIONSHIP MAPInputs, rule, and outputs

01
PREDECESSORCurrent vault outpoint
The current Bitcoin output anchors collateral and identifies the state being spent.
02
REQUESTUNIT state versus vault state
The UNIT state versus vault state workflow proposes one exact action and successor state.
03
POLICYProfile, oracle, signatures
Applicable policy, price evidence, authorization, and transaction shape are checked.
04
BITCOIN SPENDScript-valid transaction
Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules.
05
SUCCESSORNew outpoint and state
Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

Rule shown: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state.

STAGE 1 OF 5PREDECESSOR: Current vault outpoint

The current Bitcoin output anchors collateral and identifies the state being spent.

Governing relationship: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state. Complete path: 1. PREDECESSOR, Current vault outpoint. The current Bitcoin output anchors collateral and identifies the state being spent. 2. REQUEST, UNIT state versus vault state. The UNIT state versus vault state workflow proposes one exact action and successor state. 3. POLICY, Profile, oracle, signatures. Applicable policy, price evidence, authorization, and transaction shape are checked. 4. BITCOIN SPEND, Script-valid transaction. Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules. 5. SUCCESSOR, New outpoint and state. Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

1. State transitionWhat exists, what changes, and what results

BEFORE

The word ledger here means a reconstructed view, not a mutable database that can override Bitcoin.

MECHANISM

A transfer may consume UNIT outputs only, while a deposit consumes the vault and BTC funding without issuing UNIT.

AFTER

Validators relate UNIT and vault state only when a defined action requires it. Ownership of tokens does not identify the debtor, and ownership of a vault does not identify ev…

Text equivalent: Starting from The word ledger here means a reconstructed view, not a mutable database that can override Bitcoin. The mechanism begins when A transfer may consume UNIT outputs only, while a deposit consumes the vault and BTC funding without issuing UNIT. The resulting lesson is Validators relate UNIT and vault state only when a defined action requires it. Ownership of tokens does not identify the debtor, and ownership of a vault does not identify every token output.

2. Mechanism pathSelect a stage to inspect its job

STAGE 1 OF 4

Read separate inputs

A transfer may consume UNIT outputs only, while a deposit consumes the vault and BTC funding without issuing UNIT.

Complete path: 1. Read separate inputs: A transfer may consume UNIT outputs only, while a deposit consumes the vault and BTC funding without issuing UNIT. 2. Apply action-specific relations: Borrow and repay require a debt differential that matches the related UNIT issue or burn. 3. Create separate successors: The token allocation and the vault successor can appear in related transactions with different outpoints and scripts. 4. Reject mismatched views: Validators must not accept a claimed debt decrease when the required UNIT burn is absent or inconsistent.

3. Rule and failure boundaryWhat accepts the result and where it can stop

ACCEPTED PATH

The worked case executes the named inputs and checks in the displayed order. Validators must not accept a claimed debt decrease when the required UNIT burn is absent or inconsistent.

CHANGED CONDITION

A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. UNIT can be received, transferred, or held independently. Debt belongs to a specific vault state.

Important distinction: A user's total UNIT wallet balance is the debt of the vaults they own. UNIT can be received, transferred, or held independently. Debt belongs to a specific vault state.

Text equivalent: The accepted path is enforced by The worked case executes the named inputs and checks in the displayed order. Validators must not accept a claimed debt decrease when the required UNIT burn is absent or inconsistent. If the required condition changes, A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. UNIT can be received, transferred, or held independently. Debt belongs to a specific vault state.

Loading lesson visuals...

Learn the idea

UNIT state maps token amounts to Bitcoin outputs. Vault state maps one loan's collateral, debt, owner, and spending commitments to its current vault output. Validators relate these views during specific actions, but neither view is a substitute for the other.

GUIDED EXPLANATION1/4 ideas inspected

Read separate inputs

A transfer may consume UNIT outputs only, while a deposit consumes the vault and BTC funding without issuing UNIT.

The worked example follows the explanation

Inspect every idea above to open it.

Important distinction“A user's total UNIT wallet balance is the debt of the vaults they own.”

UNIT can be received, transferred, or held independently. Debt belongs to a specific vault state.

FINISH LEARNING FIRST

The questions unlock after every required learning activity

Inspect every guided idea, open the worked example, rebuild its mechanism, and complete the deterministic lesson tool. Your progress is saved automatically.