Sylan Vesting

Owner‑managed, non‑upgradeable vesting contract for SYL. Supports cliff + linear vesting with slice periods, revocable schedules, and pull‑payment withdrawals. Uses Solady libraries (Ownable, ReentrancyGuard, SafeTransferLib) and a minimal ERC‑20 interface.

Timestamps in this contract are seconds (Solidity block.timestamp), not milliseconds.

What it does

Lock an amount of SYL for a beneficiary and release it linearly after an optional cliff.
Allow the owner to revoke revocable schedules (releasing any vested portion first).
Keep a running total of allocated tokens so the owner can only withdraw unallocated balances.

Data model


struct VestingSchedule {
  address  beneficiary;          // who receives tokens
  uint256  cliff;                // timestamp = start + cliffSeconds
  uint256  start;                // vesting start (unix seconds)
  uint256  duration;             // total duration (seconds)
  uint256  slicePeriodSeconds;   // vest accrues in these step sizes (>=1)
  bool     revocable;            // can owner revoke?
  uint256  amountTotal;          // total allocated to this schedule
  uint256  released;             // amount already claimed
  bool     revoked;              // if true, no more vesting accrues
}

Schedule ID: keccak256(abi.encodePacked(holder, index))
Helpers: computeNextVestingScheduleIdForHolder(holder), computeVestingScheduleIdForAddressAndIndex(holder, index).

Lifecycle

1) Create

createVestingSchedule(beneficiary, start, cliffSeconds, duration, slicePeriodSeconds, revocable, amount) — onlyOwner

Checks:

amount > 0, duration > 0, slicePeriodSeconds ≥ 1, duration ≥ cliffSeconds
Contract getWithdrawableAmount() ≥ amount
Records schedule under a new scheduleId and increments the holder’s schedule count.
Emits VestingCreated(scheduleId, beneficiary, amount)

2) Release

release(scheduleId, amount) — callable by beneficiary or owner

Computes releasable via _computeReleasableAmount (see Math).
Transfers amount SYL to beneficiary and bumps released.
Emits TokensReleased(scheduleId, beneficiary, amount)

3) Revoke (optional)

revoke(scheduleId) — onlyOwner

Requires revocable == true and not already revoked.
First releases any currently vested amount, then marks the schedule revoked.
Unreleased remainder is removed from vestingSchedulesTotalAmount.
Emits VestingRevoked(scheduleId, beneficiary, unreleasedAmount)

4) Withdraw unallocated

withdraw(amount) — onlyOwner

Transfers out tokens that are not locked by active schedules.
Guarded by nonReentrant and checks amount ≤ getWithdrawableAmount().
Emits TokensWithdrawn(to, amount)

Math (releasable amount)

Let t = block.timestamp.

If t < cliff or revoked == true → 0.
If t ≥ start + duration → amountTotal - released (everything left).
Else linear with slicing:
- timeFromCliff = t - cliff
- vestedSeconds = floor(timeFromCliff / slice) * slice
- vestedAmount = amountTotal * vestedSeconds / duration
- releasable = max(vestedAmount - released, 0)

getCurrentTime() is an internal virtual helper returning block.timestamp (useful for testing via inheritance/mocks).

External interface (selected)

Writes

createVestingSchedule(address,uint256,uint256,uint256,uint256,bool,uint256)
release(bytes32,uint256)
revoke(bytes32)
withdraw(uint256)

Reads

getVestingSchedule(bytes32) → VestingSchedule
computeReleasableAmount(bytes32) → uint256
getReleasableAmountForBeneficiary(address) → uint256 (sums across that address)
getVestingSchedulesCountByBeneficiary(address) → uint256
getVestingSchedulesCount() → uint256
getVestingSchedulesTotalAmount() → uint256
getVestingScheduleByAddressAndIndex(address,uint256) → VestingSchedule
getVestingIdAtIndex(uint256) → bytes32
getToken() → address
getWithdrawableAmount() → uint256
computeNextVestingScheduleIdForHolder(address) → bytes32
computeVestingScheduleIdForAddressAndIndex(address,uint256) → bytes32

Receive/Fallback

receive() and fallback() are present (no-op) to avoid accidental reverts on ETH transfers.

Events

VestingCreated(bytes32 scheduleId, address beneficiary, uint256 amount)
TokensReleased(bytes32 scheduleId, address beneficiary, uint256 amount)
VestingRevoked(bytes32 scheduleId, address beneficiary, uint256 unreleasedAmount)
TokensWithdrawn(address to, uint256 amount)

Minimal ABI (client claims)

For UIs that only let a beneficiary claim and inspect schedules:


[
  {"type":"function","stateMutability":"view","name":"getVestingSchedulesCountByBeneficiary","inputs":[{"name":"beneficiary","type":"address"}],"outputs":[{"type":"uint256"}]},
  {"type":"function","stateMutability":"view","name":"getVestingScheduleByAddressAndIndex","inputs":[{"name":"holder","type":"address"},{"name":"index","type":"uint256"}],"outputs":[{"type":"tuple","components":[
    {"name":"beneficiary","type":"address"},
    {"name":"cliff","type":"uint256"},
    {"name":"start","type":"uint256"},
    {"name":"duration","type":"uint256"},
    {"name":"slicePeriodSeconds","type":"uint256"},
    {"name":"revocable","type":"bool"},
    {"name":"amountTotal","type":"uint256"},
    {"name":"released","type":"uint256"},
    {"name":"revoked","type":"bool"}
  ]}]},
  {"type":"function","stateMutability":"view","name":"computeReleasableAmount","inputs":[{"name":"scheduleId","type":"bytes32"}],"outputs":[{"type":"uint256"}]},
  {"type":"function","stateMutability":"nonpayable","name":"release","inputs":[{"name":"scheduleId","type":"bytes32"},{"name":"amount","type":"uint256"}],"outputs":[]}
]

Integration tips

Decimals: token uses 18 decimals; format UI amounts accordingly.
Claim UX: display computeReleasableAmount(id) and allow partial or full release.
Safety: wrap release in a try/catch or pre‑read the releasable amount to avoid spurious reverts.
Admin UI: hide revoke unless revocable == true; warn that revoke is final and only frees the unreleased portion.

Admin & security notes

Only the owner can create schedules, revoke, and withdraw unallocated tokens.
withdraw(amount) cannot reduce reserved funds below active allocations (vestingSchedulesTotalAmount).
Consider holding ownership in a Gnosis Safe; keep the vesting contract funded before creating schedules.

Verification checklist

Schedules created for correct beneficiaries/amounts (unit tests).
Cliff/duration/slice parameters reviewed; duration ≥ cliff.
getWithdrawableAmount() always ≥ 0; treasury top‑ups tested.
Revoke path tested releases vested portion first.
getReleasableAmountForBeneficiary matches sum of individual schedules.

Out of scope for this page

Token roles & upgrades → Sylan Token page.
Addresses/ABIs → Architecture → Addresses & ABIs.
Presale/vesting allocations → see Presale and project tokenomics docs.