Hardfork Schedule

The Lethean chain defines 7 hardforks (HF0 through HF6), totalling ZANO_HARDFORKS_TOTAL = 7. Heights are specified as "after height", meaning the hardfork activates at height N+1.

Genesis

Parameter	Value
Genesis timestamp	2026-02-12 12:00 UTC
Unix timestamp	`1770897600`
Genesis nonce	`CURRENCY_FORMATION_VERSION + 101011010121`
Genesis block major version	1
Genesis block minor version	0

Hardfork Table

HF	ID	Mainnet height	Testnet height	Block major version	What changes
HF0	`ZANO_HARDFORK_00_INITAL`	0 (genesis)	0	0/1	CryptoNote base protocol. Hybrid PoW/PoS consensus from block 0. Classic ring signatures (NLSAG). Transparent amounts. Transaction version 0-1.
HF1	`ZANO_HARDFORK_01`	10,080	0	1	New transaction types. Enables HTLC (hash time-locked contracts), multisig inputs/outputs, and service attachments. ~7 days after launch.
HF2	`ZANO_HARDFORK_02`	10,080	10	1	Block time adjustment. Activates alongside HF1 on mainnet. On testnet, activates independently at height 10 for testing.
HF3	`ZANO_HARDFORK_03`	999,999,999	0	2	Block version 2. Increments `major_version` to 2 (`HF3_BLOCK_MAJOR_VERSION`). Preparation for Zarcanum. Future activation on mainnet.
HF4	`ZANO_HARDFORK_04_ZARCANUM`	999,999,999	100	3	Zarcanum privacy upgrade. Confidential transactions (hidden amounts). Stealth outputs (`tx_out_zarcanum`). CLSAG ring signatures (GG, GGX, GGXXG variants). Bulletproofs+ range proofs. Mandatory decoy set increased from 10 to 15. Minimum 2 outputs per transaction. Transaction version 2. Minimum coinage of 10 blocks for staking. 60-block transaction freeze period before hardfork activation (from HF5 onwards).
HF5	`ZANO_HARDFORK_05`	999,999,999	200	3	Confidential assets. Asset deployment, emission, update, and burn operations. Asset surjection proofs (BGE). Transaction version 3 with `hardfork_id` field. Minimum build version 601 (mainnet) / 2 (testnet).
HF6	`ZANO_HARDFORK_06`	999,999,999	999,999,999	3	Block time halving. PoW and PoS targets double from 120s to 240s. Blocks per day halve from ~1440 to ~720. Effectively halves the emission rate without changing the per-block reward. Minimum build version 601 (mainnet) / 2 (testnet). Reserved for future activation.

Transaction Version Progression

Transaction version	Constant	Introduced	Description
0	`TRANSACTION_VERSION_INITAL`	Genesis	Original CryptoNote format
1	`TRANSACTION_VERSION_PRE_HF4`	HF1	Extended format with HTLC, multisig
2	`TRANSACTION_VERSION_POST_HF4`	HF4	Zarcanum confidential transactions
3	`TRANSACTION_VERSION_POST_HF5`	HF5	Confidential assets, hardfork ID field

Block Version Progression

Block major version	Constant	Hardfork	Description
0	`BLOCK_MAJOR_VERSION_INITIAL`	Pre-HF1	Initial version
1	`HF1_BLOCK_MAJOR_VERSION`	HF1	After first hardfork
2	`HF3_BLOCK_MAJOR_VERSION`	HF3	Block format v2
3	`CURRENT_BLOCK_MAJOR_VERSION`	HF4+	Current format

Pre-Hardfork Transaction Freeze

Starting from HF5, a transaction freeze period of CURRENCY_PRE_HARDFORK_TX_FREEZE_PERIOD = 60 blocks applies before each hardfork activation. During this window, no new transactions (other than coinbase) are accepted into the mempool. This ensures the chain stabilises before consensus rule changes take effect.

Notes

Heights 999,999,999 indicate future activation. These hardforks are defined in code but not yet scheduled for mainnet.
On testnet, HF1 and HF3 activate at genesis (height 0), allowing immediate testing of all features.
HF4 (ZANO_HARDFORK_04_TIMESTAMP_ACTUAL) references the genesis timestamp 1770897600 for Zarcanum proof initialisation.
HF1 and HF2 share the same mainnet activation height (10,080), activating simultaneously approximately 7 days after chain launch.