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feat: update Apex Vault contract for Clarity 4 compliance and yield handling #1

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feat: update Apex Vault contract for Clarity 4 compliance and yield handling #1

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234 changes: 61 additions & 173 deletions contracts/apex-vault-real.clar
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Original file line number Diff line number Diff line change
@@ -1,211 +1,99 @@
;; title: apex-vault-real
;; version: 2.0.0
;; version: 2.0.1
;; summary: Apex Yield Vault - Yield-bearing vault for USDCx
;; description: A DeFi vault that accepts USDCx deposits and issues apUSDCx share tokens.
;; Implements block-based yield simulation for demo purposes.
;; Integrates with the official Circle USDCx token on Stacks.
;; Written for Clarity 4 with asset restriction safety.

;; traits
;;
(impl-trait .sip-010-trait.sip-010-trait)

;; token definitions
;;
(define-fungible-token ap-usdcx)

;; constants
;;
(define-constant ERR-ZERO-AMOUNT (err u1001))
(define-constant ERR-NOT-TOKEN-OWNER (err u100))

;; USDCx token contract (official Circle deployment on Stacks Testnet)
(define-constant USDCX-CONTRACT 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.usdcx)

;; Yield parameters: 10 basis points per 100 blocks (~13.5% APY at 10min blocks)
;; NOTE: This is simulated yield for demo. Production would integrate with Zest/Bitflow.
(define-constant YIELD-RATE-BPS u10)
(define-constant BLOCKS-PER-ACCRUE u100)

;; data vars
;;
(define-data-var total-assets uint u0)
(define-data-var last-accrue-block uint stacks-block-height)

;; data maps
;;

;; private functions
;;

;; Accrue yield based on elapsed blocks
;; accrue yield based on blocks elapsed
(define-private (accrue-yield-internal)
(let (
(current-block stacks-block-height)
(last-block (var-get last-accrue-block))
(blocks-elapsed (- current-block last-block))
(periods (/ blocks-elapsed BLOCKS-PER-ACCRUE))
)
(let ((current-block stacks-block-height)
(last-block (var-get last-accrue-block))
(blocks-elapsed (- current-block last-block))
(periods (/ blocks-elapsed BLOCKS-PER-ACCRUE)))
(if (> periods u0)
(let (
(assets (var-get total-assets))
;; Yield = assets * periods * YIELD-RATE-BPS / 10000
(yield-amount (/ (* assets (* periods YIELD-RATE-BPS)) u10000))
)
(var-set total-assets (+ assets yield-amount))
(var-set last-accrue-block current-block)
true
)
false
)
)
)

;; read only functions
;;

;; Get total assets in vault
(define-read-only (get-total-assets)
(var-get total-assets)
)

;; Get current exchange rate (assets per share, 6 decimals)
(let ((assets (var-get total-assets))
(yield-amount (/ (* assets (* periods YIELD-RATE-BPS)) u10000)))
(var-set total-assets (+ assets yield-amount))
(var-set last-accrue-block current-block)
true)
false)))

;; read-only functions
(define-read-only (get-total-assets) (var-get total-assets))
(define-read-only (get-exchange-rate)
(let ((supply (ft-get-supply ap-usdcx)))
(if (is-eq supply u0)
u1000000 ;; 1.0 with 6 decimals
(/ (* (var-get total-assets) u1000000) supply)
)
)
)

;; Preview shares received for deposit amount
u1000000
(/ (* (var-get total-assets) u1000000) supply))))
(define-read-only (preview-deposit (amount uint))
(let ((supply (ft-get-supply ap-usdcx)))
(if (is-eq supply u0)
amount
(/ (* amount supply) (var-get total-assets))
)
)
)

;; Preview assets received for share amount
amount
(/ (* amount supply) (var-get total-assets)))))
(define-read-only (preview-withdraw (shares uint))
(let ((supply (ft-get-supply ap-usdcx)))
(if (is-eq supply u0)
u0
(/ (* shares (var-get total-assets)) supply)
)
)
)

;; Get last accrue block
(define-read-only (get-last-accrue-block)
(var-get last-accrue-block)
)

;; Get contract principal (Clarity 4)
(define-read-only (get-vault-principal)
current-contract
)

;; SIP-010: Get name
(define-read-only (get-name)
(ok "Apex Yield USDC")
)

;; SIP-010: Get symbol
(define-read-only (get-symbol)
(ok "apUSDCx")
)

;; SIP-010: Get decimals
(define-read-only (get-decimals)
(ok u6)
)

;; SIP-010: Get balance
(define-read-only (get-balance (who principal))
(ok (ft-get-balance ap-usdcx who))
)

;; SIP-010: Get total supply
(define-read-only (get-total-supply)
(ok (ft-get-supply ap-usdcx))
)

;; SIP-010: Get token URI
(define-read-only (get-token-uri)
(ok none)
)

;; public functions
;;

;; Deposit USDCx and receive apUSDCx shares
;; Uses the official Circle USDCx token deployed at ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.usdcx
(if (is-eq supply u0) u0
(/ (* shares (var-get total-assets)) supply))))
(define-read-only (get-last-accrue-block) (var-get last-accrue-block))
(define-read-only (get-vault-principal) current-contract)
(define-read-only (get-name) (ok "Apex Yield USDC"))
(define-read-only (get-symbol) (ok "apUSDCx"))
(define-read-only (get-decimals) (ok u6))
(define-read-only (get-balance (who principal)) (ok (ft-get-balance ap-usdcx who)))
(define-read-only (get-total-supply) (ok (ft-get-supply ap-usdcx)))
(define-read-only (get-token-uri) (ok none))

;; deposit USDCx and mint apUSDCx
(define-public (deposit (amount uint))
(let (
(shares (preview-deposit amount))
(sender tx-sender)
(vault-principal current-contract)
)
(begin (accrue-yield-internal))
(asserts! (> amount u0) ERR-ZERO-AMOUNT)

;; Transfer USDCx from user to vault (using real Circle USDCx token)
(try! (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.usdcx transfer amount sender vault-principal none))

;; Mint shares to user
(try! (ft-mint? ap-usdcx shares sender))

;; Update total assets
(var-set total-assets (+ (var-get total-assets) amount))

(print { event: "deposit", amount: amount, shares: shares, user: sender })
(ok shares)
)
)

;; Withdraw USDCx by burning apUSDCx shares
;; Uses Clarity 4 as-contract? with explicit asset allowances for security
(let ((shares (preview-deposit amount))
(sender tx-sender)
(vault-principal current-contract))
(begin
(accrue-yield-internal)
(asserts! (> amount u0) ERR-ZERO-AMOUNT)
(try! (contract-call? USDCX-CONTRACT transfer amount sender vault-principal none))
(try! (ft-mint? ap-usdcx shares sender))
(var-set total-assets (+ (var-get total-assets) amount))
(print { event: "deposit", amount: amount, shares: shares, user: sender })
(ok shares))))

;; withdraw USDCx by burning apUSDCx
(define-public (withdraw (shares uint))
(let (
(assets (preview-withdraw shares))
(sender tx-sender)
)
(begin (accrue-yield-internal))
(asserts! (> shares u0) ERR-ZERO-AMOUNT)

;; Burn shares from user
(try! (ft-burn? ap-usdcx shares sender))

;; Transfer USDCx from vault to user using Clarity 4 as-contract? with FT allowance
;; Uses the real Circle USDCx token - fungible token is named "usdcx-token" in the contract
(try! (as-contract?
((with-ft 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.usdcx "usdcx-token" assets))
(unwrap-panic (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.usdcx transfer assets tx-sender sender none))
))

;; Update total assets
(var-set total-assets (- (var-get total-assets) assets))

(print { event: "withdraw", amount: assets, shares: shares, user: sender })
(ok assets)
)
)

;; Manually trigger yield accrual (for demo/testing)
(define-public (harvest)
(ok (accrue-yield-internal))
)

;; SIP-010: Transfer shares between users
(let ((assets (preview-withdraw shares))
(sender tx-sender)
(vault-principal current-contract))
(begin
(accrue-yield-internal)
(asserts! (> shares u0) ERR-ZERO-AMOUNT)
(try! (ft-burn? ap-usdcx shares sender))
(try! (as-contract (contract-call? USDCX-CONTRACT transfer assets vault-principal sender none)))
(var-set total-assets (- (var-get total-assets) assets))
(print { event: "withdraw", amount: assets, shares: shares, user: sender })
(ok assets))))

;; manually accrue yield
(define-public (harvest) (ok (accrue-yield-internal)))

;; transfer apUSDCx shares
(define-public (transfer (amount uint) (sender principal) (recipient principal) (memo (optional (buff 34))))
(begin
(asserts! (is-eq tx-sender sender) ERR-NOT-TOKEN-OWNER)
(try! (ft-transfer? ap-usdcx amount sender recipient))
(match memo to-print (print to-print) 0x)
(ok true)
)
)
(ok true)))