`InitiateTransfer`, the new instruction introduced in XCMv5, allows
preserving the origin after a cross-chain transfer via the usage of the
`AliasOrigin` instruction. The receiving chain needs to be configured to
allow such this instruction to have its intended effect and not just
throw an error.

In this PR, I add the alias rules specified in the [RFC for origin
preservation](https://github.com/polkadot-fellows/RFCs/blob/main/text/0122-alias-origin-on-asset-transfers.md)
to westend chains so we can test these scenarios in the testnet.

The new scenarios include:
- Sending a cross-chain transfer from one system chain to another and
doing a Transact on the same message (1 hop)
- Sending a reserve asset transfer from one chain to another going
through asset hub and doing Transact on the same message (2 hops)

The updated chains are:
- Relay: added `AliasChildLocation`
- Collectives: added `AliasChildLocation` and
`AliasOriginRootUsingFilter<AssetHubLocation, Everything>`
- People: added `AliasChildLocation` and
`AliasOriginRootUsingFilter<AssetHubLocation, Everything>`
- Coretime: added `AliasChildLocation` and
`AliasOriginRootUsingFilter<AssetHubLocation, Everything>`

AssetHub already has `AliasChildLocation` and doesn't need the other
config item.
BridgeHub is not intended to be used by end users so I didn't add any
config item.
Only added `AliasChildOrigin` to the relay since we intend for it to be
used less.

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: command-bot <>

After finality started lagging on kusama around `2025-11-25 15:55:40`
nodes started being overloaded with messages and some restarted with
```
Subsystem approval-distribution-subsystem appears unresponsive when sending a message of type polkadot_node_subsystem_types::messages::ApprovalDistributionMessage. origin=polkadot_service::relay_chain_selection::SelectRelayChainInner<sc_client_db::Backend<sp_runtime::generic::block::Block<sp_runtime::generic::header::Header<u32, sp_runtime::traits::BlakeTwo256>, sp_runtime::OpaqueExtrinsic>>, polkadot_overseer::Handle>
```

I think this happened because our aggression in the current form is way
too spammy and create problems in situation where we already constructed
blocks with a load of candidates to check which what happened around
`#25933682` before and after. However aggression, does help in the
nightmare scenario where the network is segmented and sparsely
connected, so I tend to think we shouldn't completely remove it.

The current configuration is:
```
l1_threshold: Some(16),
l2_threshold: Some(28),
resend_unfinalized_period: Some(8),
```
The way aggression works right now :
1. After L1 is triggered all nodes send all messages they created to all
the other nodes and all messages they would have they already send
according to the topology.
2. Because of resend_unfinalized_period for each block all messages at
step 1) are sent every 8 blocks, so for example let's say we have blocks
1 to 24 unfinalized, then at block 25, all messages for block 1, 9 will
be resent, and consequently at block 26, all messages for block 2, 10
will be resent, this becomes worse as more blocks are created if backing
backpressure did not kick in yet. In total this logic makes that each
node receive 3 * total_number_of messages_per_block
3. L2 aggression is way too spammy, when L2 aggression is enabled all
nodes sends all messages of a block on GridXY, that means that all
messages are received and sent by node at least 2*sqrt(num_validators),
so on kusama would be 66 * NUM_MESSAGES_AT_FIRST_UNFINALIZED_BLOCK, so
even with a reasonable number of messages like 10K, which you can have
if you escalated because of no shows, you end-up sending and receiving
~660k messages at once, I think that's what makes the
approval-distribution to appear unresponsive on some nodes.
4. Duplicate messages are received by the nodes which turn, mark the
node as banned, which may create more no-shows.

## Proposed improvements:
1. Make L2 trigger way later 28 blocks, instead of 64, this should
literally the last resort, until then we should try to let the
approval-voting escalation mechanism to do its things and cover the
no-shows.
2. On L1 aggression don't send messages for blocks too far from the
first_unfinalized there is no point in sending the messages for block
20, if block 1 is still unfinalized.
3. On L1 aggression, send messages then back-off for 3 *
resend_unfinalized_period to give time for everyone to clear up their
queues.
4. If aggression is enabled accept duplicate messages from validators
and don't punish them by reducting their reputation which, which may
create no-shows.

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>
Co-authored-by: Andrei Sandu <54316454+sandreim@users.noreply.github.com>

# Description
Migrated polkadot-runtime-common auctions benchmarking to the new
benchmarking syntax v2.
This is part of #6202

---------

Co-authored-by: Giuseppe Re <giuseppe.re@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>

## Description

Our smoke tests transfer `WETH` from Sepolia to Westend-AssetHub breaks,
try to reregister `WETH` on AH but fails as following:


https://bridgehub-westend.subscan.io/xcm_message/westend-4796d6b3600aca32ef63b9953acf6a456cfd2fbe

https://assethub-westend.subscan.io/extrinsic/9731267-0?event=9731267-2

The reason is that the transact call encoded on BH to register the asset

https://github.com/paritytech/polkadot-sdk/blob/a77940ba

/bridges/snowbridge/primitives/router/src/inbound/mod.rs#L282-L289
```
0x3500020209079edaa8020300fff9976782d46cc05630d1f6ebab18b2324d6b1400ce796ae65569a670d0c1cc1ac12515a3ce21b5fbf729d63d7b289baad070139d01000000000000000000000000000000
```

the `asset_id` which is the xcm location can't be decoded on AH in V5

Issue initial post in
https://matrix.to/#/!qUtSTcfMJzBdPmpFKa:parity.io/$RNMAxIIOKGtBAqkgwiFuQf4eNaYpmOK-Pfw4d6vv1aU?via=parity.io&via=matrix.org&via=web3.foundation

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

The way we build the messages we need to send to approval-distribution
can result in a situation where is we have multiple assignments covered
by a coalesced approval, the messages are sent in this order:

ASSIGNMENT1, APPROVAL, ASSIGNMENT2, because we iterate over each
candidate and add to the queue of messages both the assignment and the
approval for that candidate, and when the approval reaches the
approval-distribution subsystem it won't be imported and gossiped
because one of the assignment for it is not known.

So in a network where a lot of nodes are restarting at the same time we
could end up in a situation where a set of the nodes correctly received
the assignments and approvals before the restart and approve their
blocks and don't trigger their assignments. The other set of nodes
should receive the assignments and approvals after the restart, but
because the approvals never get broacasted anymore because of this bug,
the only way they could approve is if other nodes start broadcasting
their assignments.

I think this bug contribute to the reason the network did not recovered
on `25-11-25 15:55:40` after the restarts.

Tested this scenario with a `zombienet` where `nodes` are finalising
blocks because of aggression and all nodes are restarted at once and
confirmed the network lags and doesn't recover before and it does after
the fix

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

Close: #5858

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

# Description

Sending XCM messages to other chains requires paying a "transport fee".
This can be paid either:
- from `origin` local account if `jit_withdraw = true`,
- taken from Holding register otherwise.

This currently works for following hops/scenarios:
1. On destination no transport fee needed (only sending costs, not
receiving),
2. Local/originating chain: just set JIT=true and fee will be paid from
signed account,
3. Intermediary hops - only if intermediary is acting as reserve between
two untrusted chains (aka only for `DepositReserveAsset` instruction) -
this was fixed in https://github.com/paritytech/polkadot-sdk/pull/3142

But now we're seeing more complex asset transfers that are mixing
reserve transfers with teleports depending on the involved chains.

# Example

E.g. transferring DOT between Relay and parachain, but through AH (using
AH instead of the Relay chain as parachain's DOT reserve).

In the `Parachain --1--> AssetHub --2--> Relay` scenario, DOT has to be
reserve-withdrawn in leg `1`, then teleported in leg `2`.
On the intermediary hop (AssetHub), `InitiateTeleport` fails to send
onward message because of missing transport fees. We also can't rely on
`jit_withdraw` because the original origin is lost on the way, and even
if it weren't we can't rely on the user having funded accounts on each
hop along the way.

# Solution/Changes

- Charge the transport fee in the executor from the transferred assets
(if available),
- Only charge from transferred assets if JIT_WITHDRAW was not set,
- Only charge from transferred assets if unless using XCMv5 `PayFees`
where we do not have this problem.

# Testing

Added regression tests in emulated transfers.

Fixes https://github.com/paritytech/polkadot-sdk/issues/4832
Fixes https://github.com/paritytech/polkadot-sdk/issues/6637

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>

After finality started lagging on kusama around 025-11-25 15:55:40
validators started seeing ocassionally this log, when importing votes
covering more than one assignment.
```
Possible bug: Vote import failed
```

That happens because the assumption that assignments from the same
validator would have the same required routing doesn't hold after you
enabled aggression, so you might end up receiving the first assignment
then you modify the routing for it in `enable_aggression` then your
receive the second assignment and the vote covering both assignments, so
the rouing for the first and second assingment wouldn't match and we
would fail to import the vote.

From the logs I've seen, I don't think this is the reason the network
didn't fully recover until the failsafe kicked it, because the votes had
been already imported in approval-voting before this error.

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

- change bench to default to old CLI
- fix profile to production

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: command-bot <>

Last feature we wanted for V5, changing `SetAssetClaimer` to be just one
of many possible "hints" that you can specify at the beginning of your
program to change its behaviour.

This makes it easier to add new hints in the future and have barriers
accept them.

---------

Co-authored-by: GitHub Action <action@github.com>

Co-authored-by: command-bot <>

Closes: https://github.com/paritytech/polkadot-sdk/issues/6585

Removing the `require_weight_at_most` parameter in V5 Transact had only
one problem. Converting a message from V5 to V4 to send to chains that
didn't upgrade yet. The conversion would not know what weight to give to
the Transact, since V4 and below require it.

To fix this, I added back the weight in the form of an `Option<Weight>`
called `fallback_max_weight`. This can be set to `None` if you don't
intend to deal with a chain that hasn't upgraded yet. If you set it to
`Some(_)`, the behaviour is the same. The plan is to totally remove this
in V6 since there will be a good conversion path from V6 to V5.

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

This might actually happen in non malicious cases.

Co-authored-by: eskimor <eskimor@no-such-url.com>

# Description
Migrated pallet-xcm-benchmarks to benchmaking syntax V2
This is part of #6202

---------

Co-authored-by: Giuseppe Re <giuseppe.re@parity.io>

The `query_weight_to_asset_fee` function was trying to convert versions
by using `try_as`, this function [doesn't convert from a versioned to a
concrete
type](https://github.com/paritytech/polkadot-sdk/blob/0156ca8f/polkadot/xcm/src/lib.rs#L131).
This would cause all calls with a lower version to fail.

The correct function to use is the good old
[try_into](https://github.com/paritytech/polkadot-sdk/blob/0156ca8f

/polkadot/xcm/src/lib.rs#L184).
Now those calls work :)

---------

Co-authored-by: command-bot <>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: GitHub Action <action@github.com>

This PR addresses two small fixes:  

1. Fixed a typo ("as as") found on the way.  
2. Resolved a bug in the `local/remote exporters` used for bridging.
Previously, they consumed `dest` and `msg` without returning them when
inner routers/exporters failed with `NotApplicable`. This PR ensures
compliance with the
[`SendXcm`](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/src/v5/traits.rs#L449-L450)
and
[`ExportXcm`](https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/xcm/xcm-executor/src/traits/export.rs#L44-L45)
traits.

---------

Co-authored-by: GitHub Action <action@github.com>

Closes #6415 

# Description

Remove unused message `ReportCollator` and test related to this message
on the collator protocol validator side.

cc: @tdimitrov



---------

Co-authored-by: Tsvetomir Dimitrov <tsvetomir@parity.io>
Co-authored-by: command-bot <>

Co-authored-by: Robert <robert@gonimo.com>
Co-authored-by: ordian <write@reusable.software>

Step in https://github.com/paritytech/polkadot-sdk/issues/3268

This PR adds the ability for these pallets to specify their source of
the block number. This is useful when these pallets are migrated from
the relay chain to a parachain and vice versa.

This change is backwards compatible:
1. If the `BlockNumberProvider` continues to use the system pallet's
block number
2. When a pallet deployed on the relay chain is moved to a parachain,
but still uses the relay chain's block number

However, we would need migrations if the deployed pallets are upgraded
on an existing parachain, and the `BlockNumberProvider` uses the relay
chain block number.

---------

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

This pull request forward all the logging directives given to the node
via `RUST_LOG` or `-l` to the workers, instead of only forwarding
`RUST_LOG`.

---------

Co-authored-by: GitHub Action <action@github.com>

Aims to implement Stage 3 of Validator Disbling as outlined here:
https://github.com/paritytech/polkadot-sdk/issues/4359

Features:
- [x] New Disabling Strategy (Staking level)
- [x] Re-enabling logic (Session level)
- [x] More generic disabling decision output
- [x] New Disabling Events

Testing & Security:
- [x] Unit tests
- [x] Mock tests
- [x] Try-runtime checks
- [x] Try-runtime tested on westend snap
- [x] Try-runtime CI tests
- [ ] Re-enabling Zombienet Test (?)
- [ ] SRLabs Audit

Closes #4745 
Closes #2418

---------

Co-authored-by: ordian <write@reusable.software>
Co-authored-by: Ankan <10196091+Ank4n@users.noreply.github.com>
Co-authored-by: Tsvetomir Dimitrov <tsvetomir@parity.io>

Since async backing parameters runtime api is released on all networks
the code in backing subsystem can be simplified by removing the usages
of `ProspectiveParachainsMode` and keeping only the branches of the code
under `ProspectiveParachainsMode::Enabled`.

The PR does that and reworks the tests in mod.rs to use async backing.
It's a preparation for
https://github.com/paritytech/polkadot-sdk/issues/5079

---------

Co-authored-by: Alin Dima <alin@parity.io>
Co-authored-by: command-bot <>

Follow up to https://github.com/paritytech/polkadot-sdk/pull/3685
Partially fixes https://github.com/paritytech/polkadot-sdk/issues/6403

The main PR introduced bare support for the new extension version byte
as well as extension weights and benchmarking.

This PR:
- Removes the redundant extension version byte from the signed v4
extrinsic, previously unused and defaulted to 0.
- Adds the extension version byte to the inherited implication passed to
`General` transactions.
- Whitelists the `pallet_authorship::Author`, `frame_system::Digest` and
`pallet_transaction_payment::NextFeeMultiplier` storage items as they
are read multiple times by extensions for each transaction, but are hot
in memory and currently overestimate the weight.
- Whitelists the benchmark caller for `CheckEra` and `CheckGenesis` as
the reads are performed for every transaction and overestimate the
weight.
- Updates the umbrella frame weight template to work with the system
extension changes.
- Plans on re-running the benchmarks at least for the `frame_system`
extensions.

---------

Signed-off-by: georgepisaltu <george.pisaltu@parity.io>
Co-authored-by: command-bot <>
Co-authored-by: gui <gui.thiolliere@gmail.com>

## Issue
[[#3421] backing: improve session buffering for runtime
information](https://github.com/paritytech/polkadot-sdk/issues/3421)

## Description
In the current implementation of the backing module, certain pieces of
information, which remain unchanged throughout a session, are fetched
multiple times via runtime API calls. The goal of this task was to
introduce a local cache to store such session-stable information and
perform the runtime API call only once per session.

This PR implements caching specifically for the validators list, node
features, executor parameters, minimum backing votes threshold, and
validator-to-group mapping, which were previously fetched from the
runtime or computed each time `PerRelayParentState` was built. Now, this
information is cached and reused within the session.

## TODO
* [X] Create a separate struct for per-session caches;
* [X] Cache validators list;
* [X] Cache node features;
* [X] Cache executor parameters;
* [X] Cache minimum backing votes threshold;
* [X] Cache validator-to-group mapping;
* [X] Update tests to reflect these changes;
* [X] Add prdoc.

## For the next PR
Cache validator groups and any other session-stable data (if present).

# Description

Part of https://github.com/paritytech/polkadot-sdk/issues/3326
Removes all pallet::getter occurrences from pallet-staking and replaces
them with explicit implementations.
Adds tests to verify that retrieval of affected entities works as
expected so via storage::getter.

## Review Notes

1. Traits added to the `derive` attribute are used in tests (either
directly or indirectly).
2. The getters had to be placed in a separate impl block since the other
one is annotated with `#[pallet::call]` and that requires
`#[pallet::call_index(0)]` annotation on each function in that block. So
I thought it's better to separate them.

---------

Co-authored-by: Dónal Murray <donal.murray@parity.io>
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

[Tx ext stage 2: 1/4] Add `TransactionSource` as argument in `TransactionExtension::validate` (#6323)

## Meta 

This PR is part of 4 PR:
* https://github.com/paritytech/polkadot-sdk/pull/6323
* https://github.com/paritytech/polkadot-sdk/pull/6324
* https://github.com/paritytech/polkadot-sdk/pull/6325
* https://github.com/paritytech/polkadot-sdk/pull/6326

## Description

One goal of transaction extension is to get rid or unsigned
transactions.
But unsigned transaction validation has access to the
`TransactionSource`.

The source is used for unsigned transactions that the node trust and
don't want to pay upfront.
Instead of using transaction source we could do: the transaction is
valid if it is signed by the block author, conceptually it should work,
but it doesn't look so easy.

This PR add `TransactionSource` to the validate function for transaction
extensions

# Description

The debug message was added to identify a potential memory leak.
However, recent observations show that pruning works as expected.
Therefore, it is best to remove this line, as it generates quite
annoying logs.


## Integration

Doesn't affect downstream projects.

---------

Co-authored-by: GitHub Action <action@github.com>

Added `ExecuteWithOrigin` instruction according to the old XCM RFC 38:
https://github.com/polkadot-fellows/xcm-format/pull/38.

This instruction allows you to descend or clear while going back again.

## TODO
- [x] Implementation
- [x] Unit tests
- [x] Integration tests
- [x] Benchmarks
- [x] PRDoc

## Future work

Modify `WithComputedOrigin` barrier to allow, for example, fees to be
paid with a descendant origin using this instruction.

---------

Signed-off-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: Andrii <ndk@parity.io>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>
Co-authored-by: Joseph Zhao <65984904+programskillforverification@users.noreply.github.com>
Co-authored-by: Nazar Mokrynskyi <nazar@mokrynskyi.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: command-bot <>

Closes #2082

change send xcm to use `xcm::executor::FeeManager` to determine if the
sender should be charged.

I had to change the `FeeManager` of the penpal config to ensure the same
test behaviour as before. For the other tests, I'm using the
`FeeManager` from the `xcm::executor::FeeManager` as this one is used to
check if the fee can be waived on the charge fees method.

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>
Co-authored-by: GitHub Action <action@github.com>

# Description

This seems to be an old artifact of the long closed
https://github.com/paritytech/substrate/issues/6827 that I noticed when
working on related code earlier.

## Integration

`NetworkStarter` was removed, simply remove its usage:
```diff
-let (network, system_rpc_tx, tx_handler_controller, start_network, sync_service) =
+let (network, system_rpc_tx, tx_handler_controller, sync_service) =
    build_network(BuildNetworkParams {
...
-start_network.start_network();
```

## Review Notes

Changes are trivial, the only reason for this to not be accepted is if
it is desired to not start network automatically for whatever reason, in
which case the description of network starter needs to change.

# Checklist

* [x] My PR includes a detailed description as outlined in the
"Description" and its two subsections above.
* [ ] My PR follows the [labeling requirements](

https://github.com/paritytech/polkadot-sdk/blob/master/docs/contributor/CONTRIBUTING.md#Process
) of this project (at minimum one label for `T` required)
* External contributors: ask maintainers to put the right label on your
PR.

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

Kudos to @EclesioMeloJunior for noticing it 

Also added a regression test for it. The existing unit test was
exercising only the case where the full chain is reverted

---------

Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

This PR introduces usage of `build_struct_json_patch` macro in all
runtimes (also guides) within the code base.

It also fixes macro to support _field init shorthand_, and _Struct
Update_ syntax which were missing in original implementation.

Follow up of #5700 and #5813

Fixes https://github.com/paritytech/polkadot-sdk/issues/6172

Fixes https://github.com/paritytech/polkadot-sdk/issues/5530

This PR introduces the removal of backing jobs that have been back
pressured for longer than `allowedAncestryLen`, as these candidates are
no longer viable.

It is reasonable to expect a result for a backing job execution within
`allowedAncestryLen` blocks. Therefore, we set the job TTL as a relay
block number and synchronize the validation host by sending activated
leaves.

---------

Co-authored-by: Andrei Sandu <54316454+sandreim@users.noreply.github.com>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>

# Description

This is a continuation of
https://github.com/paritytech/polkadot-sdk/pull/5666 that finally fixes
https://github.com/paritytech/polkadot-sdk/issues/5333.

This should allow developers to create custom syncing strategies or even
the whole syncing engine if they so desire. It also moved syncing engine
creation and addition of corresponding protocol outside
`build_network_advanced` method, which is something Bastian expressed as
desired in
https://github.com/paritytech/polkadot-sdk/issues/5#issuecomment-1700816458

Here I replaced strategy-specific types and methods in `SyncingStrategy`
trait with generic ones. Specifically `SyncingAction` is now used by all
strategies instead of strategy-specific types with conversions.
`StrategyKey` was an enum with a fixed set of options and now replaced
with an opaque type that strategies create privately and send to upper
layers as an opaque type. Requests and responses are now handled in a
generic way regardless of the strategy, which reduced and simplified
strategy API.

`PolkadotSyncingStrategy` now lives in its dedicated module (had to edit
.gitignore for this) like other strategies.

`build_network_advanced` takes generic `SyncingService` as an argument
alongside with a few other low-level types (that can probably be
extracted in the future as well) without any notion of specifics of the
way syncing is actually done. All the protocol and tasks are created
outside and not a part of the network anymore. It still adds a bunch of
protocols like for light client and some others that should eventually
be restructured making `build_network_advanced` just building generic
network and not application-specific protocols handling.

## Integration

Just like https://github.com/paritytech/polkadot-sdk/pull/5666
introduced `build_polkadot_syncing_strategy`, this PR introduces
`build_default_block_downloader`, but for convenience and to avoid
typical boilerplate a simpler high-level function
`build_default_syncing_engine` is added that will take care of creating
typical block downloader, syncing strategy and syncing engine, which is
what most users will be using going forward. `build_network` towards the
end of the PR was renamed to `build_network_advanced` and
`build_network`'s API was reverted to
pre-https://github.com/paritytech/polkadot-sdk/pull/5666, so most users
will not see much of a difference during upgrade unless they opt-in to
use new API.

## Review Notes

For `StrategyKey` I was thinking about using something like private type
and then storing `TypeId` inside instead of a static string in it, let
me know if that would preferred.

The biggest change happened to requests that different strategies make
and how their responses are handled. The most annoying thing here is
that block response decoding, in contrast to all other responses, is
dependent on request. This meant request had to be sent throughout the
system. While originally `Response` was `Vec<u8>`, I didn't want to
re-encode/decode request and response just to fit into that API, so I
ended up with `Box<dyn Any + Send>`. This allows responses to be truly
generic and each strategy will know how to downcast it back to the
concrete type when handling the response.

Import queue refactoring was needed to move `SyncingEngine` construction
out of `build_network` that awkwardly implemented for `SyncingService`,
but due to `&mut self` wasn't usable on `Arc<SyncingService>` for no
good reason. `Arc<SyncingService>` itself is of course useless, but
refactoring to replace it with just `SyncingService` was unfortunately
rejected in https://github.com/paritytech/polkadot-sdk/pull/5454

As usual I recommend to review this PR as a series of commits instead of
as the final diff, it'll make more sense that way.

# Checklist

* [x] My PR includes a detailed description as outlined in the
"Description" and its two subsections above.
* [x] My PR follows the [labeling requirements](

https://github.com/paritytech/polkadot-sdk/blob/master/docs/contributor/CONTRIBUTING.md#Process
) of this project (at minimum one label for `T` required)
* External contributors: ask maintainers to put the right label on your
PR.
* [x] I have made corresponding changes to the documentation (if
applicable)

https://github.com/paritytech/polkadot-sdk/issues/6343

closes https://github.com/paritytech/polkadot-sdk/issues/6358

Adds the following runtime api to pallet-nomination-pools.
`pool_accounts(pool_id)`: Returns `(bonded_account, reward_account)`
associated with the `pool_id`.

cc: @rossbulat



---------

Co-authored-by: command-bot <>
Co-authored-by: Branislav Kontur <bkontur@gmail.com>