fix(staking): include netuid in ChildKeyTakeSet event

[RUNECTZ33]

Description

ChildkeyTake is a StorageDoubleMap<_, hotkey, _, netuid, u16> — per-(hotkey, netuid). The set_childkey_take dispatch accepts a netuid parameter:

pub fn do_set_childkey_take(
    coldkey: T::AccountId,
    hotkey: T::AccountId,
    netuid: NetUid,
    take: u16,
) -> DispatchResult { ... }

and the storage write at set_children.rs:764 uses that netuid:

ChildkeyTake::<T>::insert(hotkey.clone(), netuid, take);

But the emitted event at set_children.rs:774 carries only (hotkey, take):

Self::deposit_event(Event::ChildKeyTakeSet(hotkey.clone(), take));

Off-chain consumers (block explorers, validator monitors, takes-rate trackers) watching ChildKeyTakeSet have no way to correlate a take change to its subnet without re-deriving from the extrinsic args — fragile across runtime upgrades and not available to event-only subscribers.

The dispatch already has netuid in scope, so threading it through is mechanical.

Fix

Change the event signature to ChildKeyTakeSet(T::AccountId, NetUid, u16) and pass netuid at the single emission site in do_set_childkey_take.

Shape mirrors #2614 ("Add netuid to TransactionFeePaidWithAlpha event") which made the same observability fix on a different event.

Bumps spec_version 406 → 407.

Tests

Adds test_set_childkey_take_event_includes_netuid in pallets/subtensor/src/tests/children.rs. The event had no prior coverage (grep on the test tree returned no hits for ChildKeyTakeSet).

SKIP_WASM_BUILD=1 cargo test -p pallet-subtensor --lib -- \
  tests::children::test_set_childkey_take_event_includes_netuid
running 1 test
test tests::children::test_set_childkey_take_event_includes_netuid ... ok
test result: ok. 1 passed; 0 failed

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe):

Breaking Change

The event signature is extended by one positional argument. Consumers that decode events by position (Polkadot.js Apps, indexer libraries, off-chain workers) will need to update their parsers — same compatibility surface as #2614. No on-chain storage change; no migration required.

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

Related

• Companion observability fix to Add netuid to TransactionFeePaidWithAlpha event #2614 ("Add netuid to TransactionFeePaidWithAlpha event")
• Same author's adjacent PRs in flight: fix(coinbase): clear AutoStakeDestination on subnet dissolve #2652 (orphan storage cleanup on dissolve) and fix(weights): include netuid in BatchWeightItemFailed event #2654 (BatchWeightItemFailed event netuid). Each is independent in scope.

[open-junius]

looks good to me