Redemption Maturity

XPowerNfts cannot be redeemed for XPOW before their maturity date. This lock period is the fundamental tradeoff in the XPower tier system: higher levels offer greater denomination (and consequently higher staking rewards), but require longer capital commitment.

The Maturity Function

The maturity year for an NFT is computed from its mint year and level:

$$\text{maturityYear}=\text{mintYear}+2^{\lfloor \ell /3\rfloor }-1$$

Where $\lfloor \ell /3\rfloor$ is the integer division of the level by 3, producing the tier index $t$:

$$t=\frac{\ell }{3}\in \{0,1,2,\dots ,33\}$$

The maturity offset — the number of years the NFT is locked beyond its mint year — is:

$t$	Level $\ell$	Offset $2^t-1$
0	0	0 years
1	3	1 year
2	6	3 years
3	9	7 years
4	12	15 years
5	15	31 years
6	18	63 years
7	21	127 years
8	24	255 years
9	27	511 years
10	30	1,023 years
15	45	32,767 years
20	60	1,048,575 years
25	75	33,554,431 years
30	90	1,073,741,823 years
33	99	8,589,934,591 years

Redemption Check

The on-chain redemption check is:

function _redeemable(uint256 id) private view returns (bool) {
    return yearOf(id) + 2 ** (levelOf(id) / 3) - 1 <= year() || migratable();
}

An NFT is redeemable when:

$$\text{yearOf(id)}+2^{\lfloor \text{levelOf(id)}/3\rfloor }-1\le \text{year()}$$

Or during an active migration period (migratable() == true), which provides a temporary escape window for holders of otherwise immature NFTs (see the Migration documentation for details).

Single Burn

When burn(address, id, amount) is called on an immature NFT, the transaction reverts with IrredeemableIssue(id). There is no partial redemption, no penalty mechanism, and no grace period — the NFT is simply locked until its maturity year arrives.

Batch Burn

For burnBatch, all IDs in the batch are checked for maturity before any burns execute. If any ID fails the maturity check, the entire batch reverts with IrredeemableIssue(failingId). This "all-or-nothing" approach prevents partial batch execution when some IDs are still locked.

Exponential Growth of Lock Periods

The maturity offset grows exponentially with the tier index because each 3-level step doubles the lock period:

$$\text{offset}(t+1)=2^{t+1}-1=2\times 2^t-1=2\times (\text{offset}(t)+1)-1$$

This mirrors the denomination growth: denomination increases by 1,000× every 3 levels while the lock period roughly doubles. The net effect is that reward potential (denomination) grows much faster than lock duration, creating an incentive to stake at higher levels despite the longer lock.

Growth Rate Comparison

Metric	Growth per 3 levels
Denomination $D$	$\times \mathrm{1,000}$
Maturity offset	$2^{t+1}-1\approx 2\times (2^t-1)$

The denomination outpaces the lock duration by a factor of 500:1 per level step. This means the capital efficiency (XPOW per year locked) improves dramatically at higher levels.

Level-0: The Exception

Level 0 has offset $2^0-1=0$ — meaning level-0 NFTs are immediately redeemable. They can be minted and burned within the same transaction, effectively acting as a fully liquid ERC-1155 wrapper for 1 XPOW. This makes level-0 useful for:

• Testing the NFT mint/burn flow without capital lock
• Short-term holding with instant exit
• NFT holders who want exposure without time commitment

Maturity Table at Key Levels

The following table combines denomination and maturity for quick reference:

Level $\ell$	$t=\ell /3$	Denomination	Maturity Offset	Maturity (if minted in 2026)
0	0	1 XPOW	0 years	2026 (instant)
3	1	${10}^3$	1 year	2027
6	2	${10}^6$	3 years	2029
9	3	${10}^9$	7 years	2033
12	4	${10}^{12}$	15 years	2041
15	5	${10}^{15}$	31 years	2057
18	6	${10}^{18}$	63 years	2089
21	7	${10}^{21}$	127 years	2153
24	8	${10}^{24}$	255 years	2281
27	9	${10}^{27}$	511 years	2537
30	10	${10}^{30}$	1,023 years	3049
45	15	${10}^{45}$	32,767 years	~AD 34,793
60	20	${10}^{60}$	1,048,575 years	~AD 1,050,601
75	25	${10}^{75}$	33,554,431 years	~AD 33,556,457
99	33	${10}^{99}$	8,589,934,591 years	~AD 8,589,936,617

Time Horizon Analysis

Short-Term (0–10 years)

• Levels 0–6: Suitable for holders with 0–3 year time horizons
• Level 9 (7-year lock): Accessible within a typical decade-long investment window
• These levels represent the "liquid" tier of the protocol

Medium-Term (10–100 years)

• Levels 12–21: Lock periods of 15–127 years
• Suitable for institutional or multi-generational planning
• Level 21 (127 years) was minted in 2026 and matures in 2153 — most original minters will not live to redeem

Long-Term (100–1,000 years)

• Levels 24–30: 255–1,023 year lock periods
• These NFTs function more as perpetual capital instruments than redeemable deposits
• The denomination (${10}^{24}$–${10}^{30}$ XPOW) makes them suitable for protocol treasury or DAO-level positions

The "Effectively Permanent" Threshold

Around level 75 ($t=25$), the maturity offset exceeds 33 million years. This is longer than:

• The existence of hominids (~7 million years)
• The Chicxulub asteroid impact (~66 million years ago)
• Any meaningful human or institutional planning horizon

Levels at or above 75 can be considered effectively permanent — the XPOW will never be redeemable within any practical timeframe. These NFTs exist as:

• Theoretical upper bounds of the tier system
• Long-term protocol sinks that permanently remove XPOW from circulation
• Signaling instruments for extreme commitment

Early Redemption: Not Possible

The XPower protocol has no early redemption mechanism. There is no penalty fee, no partial release, and no governance override that can unlock immature NFTs. This is a deliberate design choice:

• Predictability: The lock period is mathematically determined and immutable — no discretionary authority can change it for existing NFTs
• Protocol stability: Locked XPOW provides a stable base for reward calculations and rate determination
• Commitment signaling: The inability to exit early forces honest time preference revelation, preventing speculation on short-term rate changes

The only exception is the migration mechanism (migratable() == true), which unlocks all NFTs during a contract upgrade window. Migration periods have a finite deadline (typically ~4 years) and require explicit opt-in by the NFT holder.

Maturity Year vs. Calendar Year

The maturity check uses the on-chain year() function, which returns the UTC calendar year as an integer:

function year() internal view returns (uint256) {
    return 1970 + (100 * block.timestamp) / CENTURY;
}

This means:

• Maturity is checked at year granularity, not block or second granularity
• An NFT with maturity year 2030 becomes redeemable at 2030-01-01 00:00:00 UTC (approximately)
• The check uses ≤ (not <), so maturityYear == currentYear passes
• Small variations in block timestamp near the year boundary may affect the exact cutoff by up to ~3.65 days (the precision of the centisecond factor in the year calculation)

Redeemability and Staking

An XPowerNft does not need to be unstaked to be redeemable — the maturity check is on the XPowerNft itself, not on the APowerNft. To redeem a staked NFT:

1. Unstake the APowerNft via NftTreasury.unstake() — receives the original XPowerNft back
2. Burn the XPowerNft via XPowerNft.burn() — receives the underlying XPOW

Staking does not extend the maturity period. The lock is determined solely by the XPowerNft's mint year and level. A staked NFT continues to "age" toward its maturity date and can be unstaked and redeemed as soon as it matures.

Practical Strategy

User Profile	Recommended Levels	Rationale
Short-term holder	0, 3, 6	0–3 year lock; still earns rewards when staked
Medium-term investor	9, 12	7–15 year lock; denomination starting at ${10}^9$
Long-term commitment	15, 21	31–127 year lock; significant earning power
Institutional / DAO	30, 45	1k–32k year lock; protocol-level positions
"Forever" sink	60+	Effectively permanent XPOW removal

Related Reading

• Levels and Denominations — full level table with denomination and maturity
• Minting and Upgrading — how to create and consolidate NFTs
• NFT System Overview — architecture and contract ownership