Fetching proxies per account

[vkulinich-cl]

Detailed Description

Right now there is no option to fetch all proxies per account.

Context

UI needs to pull all proxies for current account for strategies feature.
We could use indexer for that, but when removing Pure (proxy.killPure), there is no event triggered to get know if proxy was removed or not (ex: https://hydration.subscan.io/tx/0xa834d20e36e30dd0b7ffd36b4c2ebf9a19db19d775b8c438982d20bef35019e1)

Also, we would like to display those proxies and be able to remove them even if indexer is down.

Currently, to kill pure, we need to know the block number and index of event when pure was created and without indexer is not possible. So probably it's a second issue

[iamyxsh]

Proxy management for strategies UI

The UI needs to pull all proxies for a given account and be able to kill pure proxies without depending on an indexer.

1. Reverse proxy lookup

Proxies storage maps delegator -> proxies, but the UI needs the opposite: given a delegate, find all delegators.

Plan is to add a ProxyApi runtime API with proxies_for_delegate(delegate) that iterates Proxies storage off-chain on the node. Same pattern as CurrenciesApi. No on-chain cost, no migration.

A reverse index StorageMap won't work here because remove_proxies does a bulk Proxies::take() without per-proxy events, so any reverse index would silently go stale.

const result = await api.call.proxyApi.proxiesForDelegate(delegateAccountId);
// Vec<(delegator, proxy_type, delay)>

2. Can't call kill_pure without an indexer

proxy.killPure needs the block height and extrinsic index from when create_pure was called. PureCreated event doesn't include these, so without an indexer the UI can't construct the call.

Plan is to add a PureProxyCreationInfo StorageMap in pallet-proxy (SDK fork). Stores { spawner, proxy_type, index, height, ext_index } keyed by pure proxy address. Populated during create_pure, cleared during kill_pure. ~8 bytes per entry, refundable deposit on kill. No migration for existing pure proxies since we can't distinguish them from regular accounts on-chain.

const info = await api.query.proxy.pureProxyCreationInfo(pureProxyAddress);
if (info.isSome) {
  const { spawner, proxyType, index, height, extIndex } = info.unwrap();
  api.tx.proxy.killPure(spawner, proxyType, index, height, extIndex);
}

Changes

Change	Repo
ProxyApi runtime API crate + impl	hydration-node
PureProxyCreationInfo storage	polkadot-sdk fork
Benchmarks, tests, weight regen	both

@mrq1911 @enthusiastmartin