feat: add disassociate_hotkey extrinsic

[Rapiiidooo]

Description

Implements the reverse of try_associate_hotkey. The new disassociate_hotkey extrinsic allows a coldkey owner to remove the ownership link to a hotkey, provided the hotkey is not registered on any subnet and has no outstanding stake.

This was requested in #2519.

Related Issue(s)

• Closes Feature Request: Disassociate Hotkey #2519

Type of Change

• New feature (non-breaking change which adds functionality)

Breaking Change

No breaking change. This is a purely additive extrinsic.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run ./scripts/fix_rust.sh to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Implementation Details

New Extrinsic: disassociate_hotkey(origin, hotkey)

• call_index: 133
• Pays: Yes

Preconditions (all enforced with descriptive errors)

Check	Error
Hotkey must exist	HotKeyAccountNotExists
Caller must own the hotkey	NonAssociatedColdKey
Hotkey must not be registered on any subnet	HotkeyIsStillRegistered
Hotkey must have no outstanding stake (Alpha)	HotkeyHasOutstandingStake

State cleaned up on success

• Owner entry removed
• Hotkey removed from OwnedHotkeys
• Hotkey removed from StakingHotkeys
• Delegates entry removed (if present)
• HotkeyDisassociated event emitted

Tests (6 cases)

1. Happy path — associate then disassociate, verify full cleanup
2. Hotkey does not exist — returns HotKeyAccountNotExists
3. Non-owner — returns NonAssociatedColdKey
4. Still registered on subnet — returns HotkeyIsStillRegistered
5. Outstanding stake — returns HotkeyHasOutstandingStake
6. Reassociation — disassociate then re-associate with a different coldkey

Benchmark

Included for the new extrinsic.

Additional Notes

No runtime panics are possible in the implementation — all checks use ensure! macros and safe storage operations. The Alpha iterator check (iter_prefix().next().is_none()) short-circuits on the first entry, keeping the worst-case cost bounded.

[Rapiiidooo]

Tested also with local-dev-node :

Connecting to ws://127.0.0.1:9944...

== Associate hotkey ==
   coldkey (signer): Alice 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
   hotkey:           Bob   5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty

>>> SubtensorModule.try_associate_hotkey({'hotkey': '5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty'})
    signer: 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
    [OK] block: 0x4a226d5e172db4b182c919773d422f474d881cc79499b7ab5f39d1fdfd7c2fc5
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0508', 'module_id': 'Balances', 'event_id': 'Withdraw', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 255292}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Withdraw', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 255292}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0507', 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 0}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 0}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0507', 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n', 'amount': 255292}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n', 'amount': 255292}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0600', 'module_id': 'TransactionPayment', 'event_id': 'TransactionFeePaid', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'actual_fee': 255292, 'tip': 0}}, 'event_index': 6, 'module_id': 'TransactionPayment', 'event_id': 'TransactionFeePaid', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'actual_fee': 255292, 'tip': 0}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0000', 'module_id': 'System', 'event_id': 'ExtrinsicSuccess', 'attributes': {'dispatch_info': {'weight': {'ref_time': 510307000, 'proof_size': 0}, 'class': 'Normal', 'pays_fee': 'Yes'}}}, 'event_index': 0, 'module_id': 'System', 'event_id': 'ExtrinsicSuccess', 'attributes': {'dispatch_info': {'weight': {'ref_time': 510307000, 'proof_size': 0}, 'class': 'Normal', 'pays_fee': 'Yes'}}, 'topics': []}

<<< SubtensorModule.Owner(['5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty']) = 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY

<<< SubtensorModule.OwnedHotkeys(['5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY']) = ['5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty']

== Disassociate hotkey ==
   coldkey (signer): Alice 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
   hotkey:           Bob   5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty

>>> SubtensorModule.disassociate_hotkey({'hotkey': '5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty'})
    signer: 5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY
    [OK] block: 0x32d6c210834829812ab15c6125a7f6fa3e62a5fd9e941d98f8dc995df4e8741f
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0508', 'module_id': 'Balances', 'event_id': 'Withdraw', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 606367}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Withdraw', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 606367}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '077a', 'module_id': 'SubtensorModule', 'event_id': 'HotkeyDisassociated', 'attributes': {'coldkey': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'hotkey': '5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty'}}, 'event_index': 7, 'module_id': 'SubtensorModule', 'event_id': 'HotkeyDisassociated', 'attributes': {'coldkey': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'hotkey': '5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty'}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0507', 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 0}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'amount': 0}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0507', 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n', 'amount': 606367}}, 'event_index': 5, 'module_id': 'Balances', 'event_id': 'Deposit', 'attributes': {'who': '5Fxune7f71ZbpP2FoY3mhYcmM596Erhv1gRue4nsPwkxMR4n', 'amount': 606367}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0600', 'module_id': 'TransactionPayment', 'event_id': 'TransactionFeePaid', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'actual_fee': 606367, 'tip': 0}}, 'event_index': 6, 'module_id': 'TransactionPayment', 'event_id': 'TransactionFeePaid', 'attributes': {'who': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', 'actual_fee': 606367, 'tip': 0}, 'topics': []}
    event: {'phase': 'ApplyExtrinsic', 'extrinsic_idx': 6, 'event': {'event_index': '0000', 'module_id': 'System', 'event_id': 'ExtrinsicSuccess', 'attributes': {'dispatch_info': {'weight': {'ref_time': 1212457000, 'proof_size': 0}, 'class': 'Normal', 'pays_fee': 'Yes'}}}, 'event_index': 0, 'module_id': 'System', 'event_id': 'ExtrinsicSuccess', 'attributes': {'dispatch_info': {'weight': {'ref_time': 1212457000, 'proof_size': 0}, 'class': 'Normal', 'pays_fee': 'Yes'}}, 'topics': []}

<<< SubtensorModule.Owner(['5FHneW46xGXgs5mUiveU4sbTyGBzmstUspZC92UhjJM694ty']) = 5C4hrfjw9DjXZTzV3MwzrrAr9P1MJhSrvWGWqi1eSuyUpnhM

<<< SubtensorModule.OwnedHotkeys(['5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY']) = []

[open-junius]

I think we can remove the storage added in create_account_if_non_existent function. For other data like AutoStakeDestination and AutoStakeDestinationColdkeys, I am not sure if we should remove them in disassociate method. will add team to review it.