Transactions

add-collateral

Lock additional miner collateral on your own hotkey.

Tops up the hotkey's registration collateral on the subnet — for example to meet a validator-published per-machine requirement on resource subnets. Prefers free alpha already staked on that hotkey (valued at the subnet moving price) and only buys the shortfall with TAO from the coldkey. The signing coldkey must own the hotkey. The locked alpha is real stake (it appreciates with the subnet pool) but is not withdrawable: it is released back to free stake through earned miner incentive at the drain ratio snapshot the hotkey already carries, survives deregistration, and is credited against the collateral requirement on re-registration. There is no direct withdrawal path — see set_min_collateral for maintaining a level without re-locking drained funds.

Any TAO→alpha buy is fill-or-kill against rate_tolerance above spot and must be submitted MEV-shielded — collateral purchases are not allowed to clear unshielded at an unbounded AMM price.

Signer	Origin	Pallet	Wraps
`coldkey`	signed account (pallet role may apply)	SubtensorModule	`SubtensorModule.add_collateral`

Parameters

Parameter	Type	Required	Description
`netuid`	integer	yes	Subnet to lock collateral on.
`amount_tao`	number \| `"all"`	yes	TAO-value of collateral to add. Uses free stake on the hotkey first; only the shortfall is bought (that remainder must meet the staking minimum).
`hotkey_ss58`	string	no	Miner hotkey the collateral attaches to. Defaults to the wallet hotkey.
`rate_tolerance`	number	no	Maximum price move slippage protection accepts, as a fraction (0.05 = 5%). Ignored when slippage protection is disabled.

Address parameters (--hotkey, --coldkey, --dest, ...) accept a raw ss58 address, an address-book or proxy-book name, or a local wallet/hotkey name.

CLI

Preview with --dry-run (shows fee, effects, and policy result without submitting), then submit:

btcli tx add-collateral \
  --netuid <int> \
  --amount-tao <amount|all> --dry-run
btcli tx add-collateral \
  --netuid <int> \
  --amount-tao <amount|all> -w my_coldkey

Python

import bittensor as bt
from bittensor.wallet import Wallet

wallet = Wallet(name="my_coldkey", hotkey="my_hotkey")
intent = bt.AddCollateral(netuid=1, amount_tao=1.0)

sub = bt.Subtensor()
plan = sub.plan(intent, wallet)   # fee, effects, policy — no submission
result = sub.execute(intent, wallet)
if not result.success:
    print(result.error.code, result.error.remediation)

(bt.Subtensor is also the async client — async with bt.Subtensor() as client: — see The client.) Or build the intent by op name, as an agent would:

result = sub.execute_tool("add_collateral", {...}, wallet)

On-chain implementation

SubtensorModule.add_collateral — pallets/subtensor/src/macros/dispatches.rs#L2444:

#[pallet::call_index(144)]
#[pallet::weight(<T as crate::pallet::Config>::WeightInfo::add_collateral())]
pub fn add_collateral(
    origin: OriginFor<T>,
    netuid: NetUid,
    hotkey: T::AccountId,
    tao: TaoBalance,
    limit_price: TaoBalance,
) -> DispatchResult {
    Self::do_add_collateral(origin, netuid, hotkey, tao, limit_price)
}

Delegates to do_add_collateral.

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