diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 614582528d73..56716ec673f5 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -131,11 +131,6 @@ class Chain
 public:
     virtual ~Chain() = default;
 
-    // This method will remove the specified transaction and all of its descendants
-    // (transactions that spend outputs from this transaction or its descendants)
-    // from the mempool.
-    virtual bool removeTxFromMempool(const uint256& txid) = 0;
-
     //! Get current chain height, not including genesis block (returns 0 if
     //! chain only contains genesis block, nullopt if chain does not contain
     //! any blocks)
@@ -371,7 +366,7 @@ class Chain
     //! support for writing null values to settings.json.
     //! Depending on the action returned by the update function, this will either
     //! update the setting in memory or write the updated settings to disk.
-    virtual bool updateRwSetting(const std::string& name, SettingsUpdate update_function) = 0;
+    virtual bool updateRwSetting(const std::string& name, const SettingsUpdate& update_function) = 0;
 
     //! Replace a setting in <datadir>/settings.json with a new value.
     //! Null can be passed to erase the setting.
@@ -418,8 +413,7 @@ class ChainClient
     //! Load saved state.
     virtual bool load() = 0;
 
-    //! Start client execution and provide a scheduler. (Scheduler is
-    //! ignored if client is out-of-process).
+    //! Start client execution and provide a scheduler.
     virtual void start(CScheduler& scheduler) = 0;
 
     //! Shut down client.
diff --git a/src/interfaces/mining.h b/src/interfaces/mining.h
index 150295e5b7b4..589873da3229 100644
--- a/src/interfaces/mining.h
+++ b/src/interfaces/mining.h
@@ -81,6 +81,11 @@ class Mining
 public:
     virtual ~Mining() = default;
 
+    // This method will remove the specified transaction and all of its descendants
+    // (transactions that spend outputs from this transaction or its descendants)
+    // from the mempool.
+    virtual bool removeTxFromMempool(const uint256& txid) = 0;
+
     //! If this chain is exclusively used for testing
     virtual bool isTestChain() = 0;
 
diff --git a/src/ipc/CMakeLists.txt b/src/ipc/CMakeLists.txt
index 40154811124b..904d72f56e13 100644
--- a/src/ipc/CMakeLists.txt
+++ b/src/ipc/CMakeLists.txt
@@ -3,7 +3,6 @@
 # file COPYING or https://opensource.org/license/mit/.
 
 add_library(bitcoin_ipc STATIC EXCLUDE_FROM_ALL
-  capnp/chain.cpp
   capnp/mining.cpp
   capnp/protocol.cpp
   interfaces.cpp
@@ -11,10 +10,8 @@ add_library(bitcoin_ipc STATIC EXCLUDE_FROM_ALL
 )
 
 target_capnp_sources(bitcoin_ipc ${PROJECT_SOURCE_DIR}
-  capnp/chain.capnp
   capnp/common.capnp
   capnp/echo.capnp
-  capnp/handler.capnp
   capnp/init.capnp
   capnp/mining.capnp
 )
diff --git a/src/ipc/capnp/chain-types.h b/src/ipc/capnp/chain-types.h
deleted file mode 100644
index 2287f154426f..000000000000
--- a/src/ipc/capnp/chain-types.h
+++ /dev/null
@@ -1,91 +0,0 @@
-// Copyright (c) 2024 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_IPC_CAPNP_CHAIN_TYPES_H
-#define BITCOIN_IPC_CAPNP_CHAIN_TYPES_H
-
-#include <ipc/capnp/chain.capnp.proxy.h>
-#include <ipc/capnp/common.capnp.proxy-types.h>
-#include <ipc/capnp/handler.capnp.proxy-types.h>
-#include <interfaces/chain.h>
-#include <policy/fees.h>
-#include <rpc/server.h>
-
-//! Specialization of handleRpc needed because it takes a CRPCCommand& reference
-//! argument, so a manual cleanup callback is needed to free the passed
-//! CRPCCommand struct and proxy ActorCallback object.
-template <>
-struct mp::ProxyServerMethodTraits<ipc::capnp::messages::Chain::HandleRpcParams>
-{
-    using Context = ServerContext<ipc::capnp::messages::Chain,
-                                  ipc::capnp::messages::Chain::HandleRpcParams,
-                                  ipc::capnp::messages::Chain::HandleRpcResults>;
-    static ::capnp::Void invoke(Context& context);
-};
-
-//! Specialization of start method needed to provide CScheduler& reference
-//! argument.
-template <>
-struct mp::ProxyServerMethodTraits<ipc::capnp::messages::ChainClient::StartParams>
-{
-    using ChainContext = ServerContext<ipc::capnp::messages::ChainClient,
-                                       ipc::capnp::messages::ChainClient::StartParams,
-                                       ipc::capnp::messages::ChainClient::StartResults>;
-    static void invoke(ChainContext& context);
-};
-
-namespace mp {
-//! Overload CustomBuildMessage, CustomPassMessage, and CustomReadMessage to
-//! serialize interfaces::FoundBlock parameters. Custom conversion functions are
-//! needed because there is not a 1:1 correspondence between members of the C++
-//! FoundBlock class and the Cap'n Proto FoundBlockParam and FoundBlockResult
-//! structs. Separate param and result structs are needed because Cap'n Proto
-//! only has input and output parameters, not in/out parameters like C++.
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const interfaces::FoundBlock& dest,
-                        ipc::capnp::messages::FoundBlockParam::Builder&& builder);
-void CustomPassMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::FoundBlockParam::Reader& reader,
-                       ipc::capnp::messages::FoundBlockResult::Builder&& builder,
-                       std::function<void(const interfaces::FoundBlock&)>&& fn);
-void CustomReadMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::FoundBlockResult::Reader& reader,
-                       const interfaces::FoundBlock& dest);
-
-//! Overload CustomBuildMessage and CustomPassMessage to serialize
-//! interfaces::BlockInfo parameters. Custom conversion functions are needed
-//! because BlockInfo structs contain pointer and reference members, and custom
-//! code is needed to deal with their lifetimes. Specifics are described in the
-//! implementation of these functions.
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const interfaces::BlockInfo& block,
-                        ipc::capnp::messages::BlockInfo::Builder&& builder);
-void CustomPassMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::BlockInfo::Reader& reader,
-                       ::capnp::Void builder,
-                       std::function<void(const interfaces::BlockInfo&)>&& fn);
-
-//! CScheduler& server-side argument handling. Skips argument so it can
-//! be handled by ProxyServerMethodTraits ChainClient::Start code.
-template <typename Accessor, typename ServerContext, typename Fn, typename... Args>
-void CustomPassField(TypeList<CScheduler&>, ServerContext& server_context, const Fn& fn, Args&&... args)
-{
-    fn.invoke(server_context, std::forward<Args>(args)...);
-}
-
-//! CRPCCommand& server-side argument handling. Skips argument so it can
-//! be handled by ProxyServerMethodTraits Chain::HandleRpc code.
-template <typename Accessor, typename ServerContext, typename Fn, typename... Args>
-void CustomPassField(TypeList<const CRPCCommand&>, ServerContext& server_context, const Fn& fn, Args&&... args)
-{
-    fn.invoke(server_context, std::forward<Args>(args)...);
-}
-
-//! Override to avoid assert failures that would happen trying to serialize
-//! spent coins. Probably it would be best for Coin serialization code not
-//! to assert, but avoiding serialization in this case is harmless.
-bool CustomHasValue(InvokeContext& invoke_context, const Coin& coin);
-} // namespace mp
-
-#endif // BITCOIN_IPC_CAPNP_CHAIN_TYPES_H
diff --git a/src/ipc/capnp/chain.capnp b/src/ipc/capnp/chain.capnp
deleted file mode 100644
index d2d405074ab9..000000000000
--- a/src/ipc/capnp/chain.capnp
+++ /dev/null
@@ -1,196 +0,0 @@
-# Copyright (c) 2024 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-@0x94f21a4864bd2c65;
-
-using Cxx = import "/capnp/c++.capnp";
-$Cxx.namespace("ipc::capnp::messages");
-
-using Proxy = import "/mp/proxy.capnp";
-$Proxy.include("interfaces/chain.h");
-$Proxy.include("rpc/server.h");
-$Proxy.includeTypes("ipc/capnp/chain-types.h");
-
-using Common = import "common.capnp";
-using Handler = import "handler.capnp";
-
-interface Chain $Proxy.wrap("interfaces::Chain") {
-    destroy @0 (context :Proxy.Context) -> ();
-    getHeight @1 (context :Proxy.Context) -> (result :Int32, hasResult :Bool);
-    getBlockHash @2 (context :Proxy.Context, height :Int32) -> (result :Data);
-    haveBlockOnDisk @3 (context :Proxy.Context, height :Int32) -> (result :Bool);
-    getTipLocator @4 (context :Proxy.Context) -> (result :Data);
-    getActiveChainLocator @5 (context :Proxy.Context, blockHash :Data) -> (result :Data);
-    findLocatorFork @6 (context :Proxy.Context, locator :Data) -> (result :Int32, hasResult :Bool);
-    hasBlockFilterIndex @7 (context :Proxy.Context, filterType :UInt8) -> (result :Bool);
-    blockFilterMatchesAny @8 (context :Proxy.Context, filterType :UInt8, blockHash :Data, filterSet :List(Data)) -> (result :Bool, hasResult :Bool);
-    findBlock @9 (context :Proxy.Context, hash :Data, block :FoundBlockParam) -> (block :FoundBlockResult, result :Bool);
-    findFirstBlockWithTimeAndHeight @10 (context :Proxy.Context, minTime :Int64, minHeight :Int32, block :FoundBlockParam) -> (block :FoundBlockResult, result :Bool);
-    findAncestorByHeight @11 (context :Proxy.Context, blockHash :Data, ancestorHeight :Int32, ancestor :FoundBlockParam) -> (ancestor :FoundBlockResult, result :Bool);
-    findAncestorByHash @12 (context :Proxy.Context, blockHash :Data, ancestorHash :Data, ancestor :FoundBlockParam) -> (ancestor :FoundBlockResult, result :Bool);
-    findCommonAncestor @13 (context :Proxy.Context, blockHash1 :Data, blockHash2 :Data, ancestor :FoundBlockParam, block1 :FoundBlockParam, block2 :FoundBlockParam) -> (ancestor :FoundBlockResult, block1 :FoundBlockResult, block2 :FoundBlockResult, result :Bool);
-    findCoins @14 (context :Proxy.Context, coins :List(Common.Pair(Data, Data))) -> (coins :List(Common.Pair(Data, Data)));
-    guessVerificationProgress @15 (context :Proxy.Context, blockHash :Data) -> (result :Float64);
-    hasBlocks @16 (context :Proxy.Context, blockHash :Data, minHeight :Int32, maxHeight: Int32, hasMaxHeight :Bool) -> (result :Bool);
-    isRBFOptIn @17 (context :Proxy.Context, tx :Data) -> (result :Int32);
-    isInMempool @18 (context :Proxy.Context, txid :Data) -> (result :Bool);
-    hasDescendantsInMempool @19 (context :Proxy.Context, txid :Data) -> (result :Bool);
-    broadcastTransaction @20 (context :Proxy.Context, tx: Data, maxTxFee :Int64, relay :Bool) -> (error: Text, result :Bool);
-    getTransactionAncestry @21 (context :Proxy.Context, txid :Data) -> (ancestors :UInt64, descendants :UInt64, ancestorsize :UInt64, ancestorfees :Int64);
-    calculateIndividualBumpFees @22 (context :Proxy.Context, outpoints :List(Data), targetFeerate :Data) -> (result: List(Common.PairInt64(Data)));
-    calculateCombinedBumpFee @23 (context :Proxy.Context, outpoints :List(Data), targetFeerate :Data) -> (result :Int64, hasResult :Bool);
-    getPackageLimits @24 (context :Proxy.Context) -> (ancestors :UInt64, descendants :UInt64);
-    checkChainLimits @25 (context :Proxy.Context, tx :Data) -> (result :Common.ResultVoid);
-    estimateSmartFee @26 (context :Proxy.Context, numBlocks :Int32, conservative :Bool, wantCalc :Bool) -> (calc :FeeCalculation, result :Data);
-    estimateMaxBlocks @27 (context :Proxy.Context) -> (result :UInt32);
-    mempoolMinFee @28 (context :Proxy.Context) -> (result :Data);
-    relayMinFee @29 (context :Proxy.Context) -> (result :Data);
-    relayIncrementalFee @30 (context :Proxy.Context) -> (result :Data);
-    relayDustFee @31 (context :Proxy.Context) -> (result :Data);
-    havePruned @32 (context :Proxy.Context) -> (result :Bool);
-    getPruneHeight @33 (context :Proxy.Context) -> (result: Int32, hasResult: Bool);
-    isReadyToBroadcast @34 (context :Proxy.Context) -> (result :Bool);
-    isInitialBlockDownload @35 (context :Proxy.Context) -> (result :Bool);
-    shutdownRequested @36 (context :Proxy.Context) -> (result :Bool);
-    initMessage @37 (context :Proxy.Context, message :Text) -> ();
-    initWarning @38 (context :Proxy.Context, message :Common.BilingualStr) -> ();
-    initError @39 (context :Proxy.Context, message :Common.BilingualStr) -> ();
-    showProgress @40 (context :Proxy.Context, title :Text, progress :Int32, resumePossible :Bool) -> ();
-    handleNotifications @41 (context :Proxy.Context, notifications :ChainNotifications) -> (result :Handler.Handler);
-    waitForNotificationsIfTipChanged @42 (context :Proxy.Context, oldTip :Data) -> ();
-    handleRpc @43 (context :Proxy.Context, command :RPCCommand) -> (result :Handler.Handler);
-    rpcEnableDeprecated @44 (context :Proxy.Context, method :Text) -> (result :Bool);
-    rpcRunLater @45 (context :Proxy.Context, name :Text, fn: RunLaterCallback, seconds: Int64) -> ();
-    getSetting @46 (context :Proxy.Context, name :Text) -> (result :Text);
-    getSettingsList @47 (context :Proxy.Context, name :Text) -> (result :List(Text));
-    getRwSetting @48 (context :Proxy.Context, name :Text) -> (result :Text);
-    updateRwSetting @49 (context :Proxy.Context, name :Text, update: SettingsUpdateCallback) -> (result :Bool);
-    overwriteRwSetting @50 (context :Proxy.Context, name :Text, value :Text, action :Int32) -> (result :Bool);
-    deleteRwSettings @51 (context :Proxy.Context, name :Text, action: Int32) -> (result :Bool);
-    requestMempoolTransactions @52 (context :Proxy.Context, notifications :ChainNotifications) -> ();
-    hasAssumedValidChain @53 (context :Proxy.Context) -> (result :Bool);
-    removeTxFromMempool @54 (context :Proxy.Context, txid :Data) -> (result :Bool);
-}
-
-interface ChainNotifications $Proxy.wrap("interfaces::Chain::Notifications") {
-    destroy @0 (context :Proxy.Context) -> ();
-    transactionAddedToMempool @1 (context :Proxy.Context, tx :Data) -> ();
-    transactionRemovedFromMempool @2 (context :Proxy.Context, tx :Data, reason :Int32) -> ();
-    blockConnected @3 (context :Proxy.Context, role: UInt32, block :BlockInfo) -> ();
-    blockDisconnected @4 (context :Proxy.Context, block :BlockInfo) -> ();
-    updatedBlockTip @5 (context :Proxy.Context) -> ();
-    chainStateFlushed @6 (context :Proxy.Context, role: UInt32, locator :Data) -> ();
-}
-
-interface ChainClient $Proxy.wrap("interfaces::ChainClient") {
-    destroy @0 (context :Proxy.Context) -> ();
-    registerRpcs @1 (context :Proxy.Context) -> ();
-    verify @2 (context :Proxy.Context) -> (result :Bool);
-    load @3 (context :Proxy.Context) -> (result :Bool);
-    start @4 (context :Proxy.Context, scheduler :Void) -> ();
-    stop @5 (context :Proxy.Context) -> ();
-    setMockTime @6 (context :Proxy.Context, time :Int64) -> ();
-    schedulerMockForward @7 (context :Proxy.Context, time :Int64) -> ();
-}
-
-struct FeeCalculation $Proxy.wrap("FeeCalculation") {
-    est @0 :EstimationResult;
-    reason @1 :Int32;
-    desiredTarget @2 :Int32;
-    returnedTarget @3 :Int32;
-}
-
-struct EstimationResult $Proxy.wrap("EstimationResult")
-{
-    pass @0 :EstimatorBucket;
-    fail @1 :EstimatorBucket;
-    decay @2 :Float64;
-    scale @3 :UInt32;
-}
-
-struct EstimatorBucket $Proxy.wrap("EstimatorBucket")
-{
-    start @0 :Float64;
-    end @1 :Float64;
-    withinTarget @2 :Float64;
-    totalConfirmed @3 :Float64;
-    inMempool @4 :Float64;
-    leftMempool @5 :Float64;
-}
-
-struct RPCCommand $Proxy.wrap("CRPCCommand") {
-   category @0 :Text;
-   name @1 :Text;
-   actor @2 :ActorCallback;
-   argNames @3 :List(RPCArg);
-   uniqueId @4 :Int64 $Proxy.name("unique_id");
-}
-
-struct RPCArg {
-   name @0 :Text;
-   namedOnly @1: Bool;
-}
-
-interface ActorCallback $Proxy.wrap("ProxyCallback<CRPCCommand::Actor>") {
-    call @0 (context :Proxy.Context, request :JSONRPCRequest, response :Text, lastCallback :Bool) -> (error :Text $Proxy.exception("std::exception"), rpcError :Text $Proxy.exception("UniValue"), typeError :Text $Proxy.exception("UniValue::type_error"), response :Text, result: Bool);
-}
-
-struct JSONRPCRequest $Proxy.wrap("JSONRPCRequest") {
-    id @0 :Text;
-    method @1 :Text $Proxy.name("strMethod");
-    params @2 :Text;
-    mode @3 :UInt32;
-    uri @4 :Text $Proxy.name("URI");
-    authUser @5 :Text;
-    peerAddr @6 :Text;
-    version @7: Int32 $Proxy.name("m_json_version");
-}
-
-interface RunLaterCallback $Proxy.wrap("ProxyCallback<std::function<void()>>") {
-    destroy @0 (context :Proxy.Context) -> ();
-    call @1 (context :Proxy.Context) -> ();
-}
-
-struct FoundBlockParam {
-    wantHash @0 :Bool;
-    wantHeight @1 :Bool;
-    wantTime @2 :Bool;
-    wantMaxTime @3 :Bool;
-    wantMtpTime @4 :Bool;
-    wantInActiveChain @5 :Bool;
-    wantLocator @6 :Bool;
-    nextBlock @7: FoundBlockParam;
-    wantData @8 :Bool;
-}
-
-struct FoundBlockResult {
-    hash @0 :Data;
-    height @1 :Int32;
-    time @2 :Int64;
-    maxTime @3 :Int64;
-    mtpTime @4 :Int64;
-    inActiveChain @5 :Int64;
-    locator @6 :Data;
-    nextBlock @7: FoundBlockResult;
-    data @8 :Data;
-    found @9 :Bool;
-}
-
-struct BlockInfo $Proxy.wrap("interfaces::BlockInfo") {
-    # Fields skipped below with Proxy.skip are pointer fields manually handled
-    # by CustomBuildMessage / CustomPassMessage overloads.
-    hash @0 :Data $Proxy.skip;
-    prevHash @1 :Data $Proxy.skip;
-    height @2 :Int32 = -1;
-    fileNumber @3 :Int32 = -1 $Proxy.name("file_number");
-    dataPos @4 :UInt32 = 0 $Proxy.name("data_pos");
-    data @5 :Data $Proxy.skip;
-    undoData @6 :Data $Proxy.skip;
-    chainTimeMax @7 :UInt32 = 0 $Proxy.name("chain_time_max");
-}
-
-interface SettingsUpdateCallback $Proxy.wrap("ProxyCallback<interfaces::SettingsUpdate>") {
-    destroy @0 (context :Proxy.Context) -> ();
-    call @1 (context :Proxy.Context, value :Text) -> (value :Text, result: Int32, hasResult: Bool);
-}
diff --git a/src/ipc/capnp/chain.cpp b/src/ipc/capnp/chain.cpp
deleted file mode 100644
index 8a24b00a1e95..000000000000
--- a/src/ipc/capnp/chain.cpp
+++ /dev/null
@@ -1,205 +0,0 @@
-// Copyright (c) 2024 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#include <capnp/blob.h>
-#include <capnp/capability.h>
-#include <capnp/list.h>
-#include <coins.h>
-#include <interfaces/chain.h>
-#include <interfaces/handler.h>
-#include <interfaces/ipc.h>
-#include <ipc/capnp/chain-types.h>
-#include <ipc/capnp/chain.capnp.h>
-#include <ipc/capnp/chain.capnp.proxy.h>
-#include <ipc/capnp/chain.capnp.proxy-types.h>
-#include <ipc/capnp/common-types.h>
-#include <ipc/capnp/context.h>
-#include <ipc/capnp/handler.capnp.proxy.h>
-#include <mp/proxy-io.h>
-#include <mp/proxy-types.h>
-#include <mp/util.h>
-#include <primitives/block.h>
-#include <rpc/server.h>
-#include <streams.h>
-#include <uint256.h>
-#include <undo.h>
-
-#include <assert.h>
-#include <cstdint>
-#include <functional>
-#include <memory>
-#include <string>
-#include <utility>
-#include <vector>
-
-namespace mp {
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const interfaces::FoundBlock& dest,
-                        ipc::capnp::messages::FoundBlockParam::Builder&& builder)
-{
-    if (dest.m_hash) builder.setWantHash(true);
-    if (dest.m_height) builder.setWantHeight(true);
-    if (dest.m_time) builder.setWantTime(true);
-    if (dest.m_max_time) builder.setWantMaxTime(true);
-    if (dest.m_mtp_time) builder.setWantMtpTime(true);
-    if (dest.m_in_active_chain) builder.setWantInActiveChain(true);
-    if (dest.m_locator) builder.setWantLocator(true);
-    if (dest.m_next_block) CustomBuildMessage(invoke_context, *dest.m_next_block, builder.initNextBlock());
-    if (dest.m_data) builder.setWantData(true);
-}
-
-void FindBlock(const std::function<void()>& find,
-               const ipc::capnp::messages::FoundBlockParam::Reader& reader,
-               ipc::capnp::messages::FoundBlockResult::Builder&& builder,
-               interfaces::FoundBlock& found_block)
-{
-    uint256 hash;
-    int height = -1;
-    int64_t time = -1;
-    int64_t max_time = -1;
-    int64_t mtp_time = -1;
-    bool in_active_chain = -1;
-    CBlockLocator locator;
-    CBlock data;
-    if (reader.getWantHash()) found_block.hash(hash);
-    if (reader.getWantHeight()) found_block.height(height);
-    if (reader.getWantTime()) found_block.time(time);
-    if (reader.getWantMaxTime()) found_block.maxTime(max_time);
-    if (reader.getWantMtpTime()) found_block.mtpTime(mtp_time);
-    if (reader.getWantInActiveChain()) found_block.inActiveChain(in_active_chain);
-    if (reader.getWantLocator()) found_block.locator(locator);
-    if (reader.getWantData()) found_block.data(data);
-    if (reader.hasNextBlock()) {
-        interfaces::FoundBlock next_block;
-        found_block.nextBlock(next_block);
-        FindBlock(find, reader.getNextBlock(), builder.initNextBlock(), next_block);
-    } else {
-        find();
-    }
-    if (!found_block.found) return;
-    if (reader.getWantHash()) builder.setHash(ipc::capnp::ToArray(ipc::capnp::Serialize(hash)));
-    if (reader.getWantHeight()) builder.setHeight(height);
-    if (reader.getWantTime()) builder.setTime(time);
-    if (reader.getWantMaxTime()) builder.setMaxTime(max_time);
-    if (reader.getWantMtpTime()) builder.setMtpTime(mtp_time);
-    if (reader.getWantInActiveChain()) builder.setInActiveChain(in_active_chain);
-    if (reader.getWantLocator()) builder.setLocator(ipc::capnp::ToArray(ipc::capnp::Serialize(locator)));
-    if (reader.getWantData()) builder.setData(ipc::capnp::ToArray(ipc::capnp::Serialize(data)));
-    builder.setFound(true);
-}
-
-void CustomPassMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::FoundBlockParam::Reader& reader,
-                       ipc::capnp::messages::FoundBlockResult::Builder&& builder,
-                       std::function<void(const interfaces::FoundBlock&)>&& fn)
-{
-    interfaces::FoundBlock found_block;
-    FindBlock([&] { fn(found_block); }, reader, std::move(builder), found_block);
-}
-
-void CustomReadMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::FoundBlockResult::Reader& reader,
-                       const interfaces::FoundBlock& dest)
-{
-    if (!reader.getFound()) return;
-    if (dest.m_hash) *dest.m_hash = ipc::capnp::Unserialize<uint256>(reader.getHash());
-    if (dest.m_height) *dest.m_height = reader.getHeight();
-    if (dest.m_time) *dest.m_time = reader.getTime();
-    if (dest.m_max_time) *dest.m_max_time = reader.getMaxTime();
-    if (dest.m_mtp_time) *dest.m_mtp_time = reader.getMtpTime();
-    if (dest.m_in_active_chain) *dest.m_in_active_chain = reader.getInActiveChain();
-    if (dest.m_locator) *dest.m_locator = ipc::capnp::Unserialize<CBlockLocator>(reader.getLocator());
-    if (dest.m_next_block) CustomReadMessage(invoke_context, reader.getNextBlock(), *dest.m_next_block);
-    if (dest.m_data) *dest.m_data = ipc::capnp::Unserialize<CBlock>(reader.getData());
-    dest.found = true;
-}
-
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const interfaces::BlockInfo& block,
-                        ipc::capnp::messages::BlockInfo::Builder&& builder)
-{
-    // Pointer fields are annotated with Proxy.skip so need to be filled
-    // manually. Generated code would actually work correctly, though, so this
-    // could be dropped if there were a Proxy.skip(read_only=True) half-skip
-    // option.
-    builder.setHash(ipc::capnp::ToArray(block.hash));
-    if (block.prev_hash) builder.setPrevHash(ipc::capnp::ToArray(*block.prev_hash));
-    if (block.data) builder.setData(ipc::capnp::ToArray(ipc::capnp::Serialize(*block.data)));
-    if (block.undo_data) builder.setUndoData(ipc::capnp::ToArray(ipc::capnp::Serialize(*block.undo_data)));
-    // Copy the remaining fields using the code generated by Proxy.wrap.
-    mp::BuildOne<0>(mp::TypeList<interfaces::BlockInfo>(), invoke_context, builder, block);
-}
-
-void CustomPassMessage(InvokeContext& invoke_context,
-                        const ipc::capnp::messages::BlockInfo::Reader& reader,
-                        ::capnp::Void builder,
-                        std::function<void(const interfaces::BlockInfo&)>&& fn)
-{
-    // Pointer fields are annotated with Proxy.skip because code generator can't
-    // figure out pointer lifetimes to be able to implementat a ReadField
-    // implementation for the BlockInfo struct, and the default PassField
-    // function calls readfield. In theory though, code generator could create a
-    // PassField specialization for the struct which could allocate pointers for
-    // the lifetime of the call, like the code below is doing manually. This
-    // would take care of all pointer fields, though the BlockInfo.hash
-    // reference field would still need to be handled specially. Or even
-    // BlockInfo.hash field could be handled automatically if the generated code
-    // used C++20 designated member initialization.
-    const uint256 hash = ipc::capnp::ToBlob<uint256>(reader.getHash());
-    std::optional<const uint256> prev_hash;
-    std::optional<const CBlock> data;
-    std::optional<const CBlockUndo> undo_data;
-    interfaces::BlockInfo block{hash};
-    if (reader.hasPrevHash()) {
-        prev_hash.emplace(ipc::capnp::ToBlob<uint256>(reader.getPrevHash()));
-        block.prev_hash = &*prev_hash;
-    }
-    if (reader.hasData()) {
-        data.emplace(ipc::capnp::Unserialize<CBlock>(reader.getData()));
-        block.data = &*data;
-    }
-    if (reader.hasUndoData()) {
-        undo_data.emplace(ipc::capnp::Unserialize<CBlockUndo>(reader.getUndoData()));
-        block.undo_data = &*undo_data;
-    }
-    mp::ReadField(mp::TypeList<interfaces::BlockInfo>(), invoke_context,
-                  mp::Make<mp::ValueField>(reader), mp::ReadDestUpdate(block));
-    fn(block);
-}
-
-::capnp::Void ProxyServerMethodTraits<ipc::capnp::messages::Chain::HandleRpcParams>::invoke(
-    Context& context)
-{
-    auto params = context.call_context.getParams();
-    auto command = params.getCommand();
-
-    CRPCCommand::Actor actor;
-    ReadField(TypeList<decltype(actor)>(), context, Make<ValueField>(command.getActor()), ReadDestUpdate(actor));
-    std::vector<std::pair<std::string, bool>> args;
-    ReadField(TypeList<decltype(args)>(), context, Make<ValueField>(command.getArgNames()), ReadDestUpdate(args));
-
-    auto rpc_command = std::make_unique<CRPCCommand>(command.getCategory(), command.getName(), std::move(actor),
-                                               std::move(args), command.getUniqueId());
-    auto handler = context.proxy_server.m_impl->handleRpc(*rpc_command);
-    auto results = context.call_context.getResults();
-    auto result = kj::heap<ProxyServer<ipc::capnp::messages::Handler>>(std::shared_ptr<interfaces::Handler>(handler.release()), *context.proxy_server.m_context.connection);
-    result->m_context.cleanup_fns.emplace_back([rpc_command = rpc_command.release()] { delete rpc_command; });
-    results.setResult(kj::mv(result));
-    return {};
-}
-
-void ProxyServerMethodTraits<ipc::capnp::messages::ChainClient::StartParams>::invoke(ChainContext& context)
-{
-    // This method is never called because ChainClient::Start is overridden by
-    // WalletLoader::Start. The custom implementation is needed just because
-    // the CScheduler& argument this is supposed to pass is not serializable.
-    assert(0);
-}
-
-bool CustomHasValue(InvokeContext& invoke_context, const Coin& coin)
-{
-    // Spent coins cannot be serialized due to an assert in Coin::Serialize.
-    return !coin.IsSpent();
-}
-} // namespace mp
diff --git a/src/ipc/capnp/common-types.h b/src/ipc/capnp/common-types.h
index 333f90b5b254..934dae5faf3c 100644
--- a/src/ipc/capnp/common-types.h
+++ b/src/ipc/capnp/common-types.h
@@ -8,12 +8,9 @@
 #include <clientversion.h>
 #include <interfaces/types.h>
 #include <primitives/transaction.h>
-#include <protocol.h>
 #include <serialize.h>
 #include <streams.h>
 #include <univalue.h>
-#include <util/result.h>
-#include <util/translation.h>
 
 #include <cstddef>
 #include <mp/proxy-types.h>
@@ -21,10 +18,7 @@
 #include <mp/type-context.h>
 #include <mp/type-data.h>
 #include <mp/type-decay.h>
-#include <mp/type-exception.h>
-#include <mp/type-function.h>
 #include <mp/type-interface.h>
-#include <mp/type-map.h>
 #include <mp/type-message.h>
 #include <mp/type-number.h>
 #include <mp/type-optional.h>
@@ -33,29 +27,13 @@
 #include <mp/type-struct.h>
 #include <mp/type-threadmap.h>
 #include <mp/type-vector.h>
-#include <mp/type-void.h>
 #include <type_traits>
-#include <unordered_set>
 #include <utility>
 
 namespace ipc {
 namespace capnp {
-//! Convert kj::ArrayPtr to base_blob.
-template <typename T>
-inline T ToBlob(const kj::ArrayPtr<const kj::byte>& array)
-{
-    return T({array.begin(), array.begin() + array.size()});
-}
-
-//! Convert base_blob to kj::ArrayPtr.
-template <typename T>
-inline kj::ArrayPtr<const kj::byte> ToArray(const T& blob)
-{
-    return {reinterpret_cast<const kj::byte*>(blob.data()), blob.size()};
-}
-
 //! Construct a ParamStream wrapping a data stream with serialization parameters
-//! needed to pass transaction and address objects between bitcoin processes.
+//! needed to pass transaction objects between bitcoin processes.
 //! In the future, more params may be added here to serialize other objects that
 //! require serialization parameters. Params should just be chosen to serialize
 //! objects completely and ensure that serializing and deserializing objects
@@ -64,28 +42,7 @@ inline kj::ArrayPtr<const kj::byte> ToArray(const T& blob)
 template <typename S>
 auto Wrap(S& s)
 {
-    return ParamsStream{s, TX_WITH_WITNESS, CAddress::V2_NETWORK};
-}
-
-//! Serialize bitcoin value.
-template <typename T>
-DataStream Serialize(const T& value)
-{
-    DataStream stream;
-    auto wrapper{Wrap(stream)};
-    value.Serialize(wrapper);
-    return stream;
-}
-
-//! Deserialize bitcoin value.
-template <typename T>
-T Unserialize(const kj::ArrayPtr<const kj::byte>& data)
-{
-    SpanReader stream{{data.begin(), data.end()}};
-    T value;
-    auto wrapper{Wrap(stream)};
-    value.Unserialize(wrapper);
-    return value;
+    return ParamsStream{s, TX_WITH_WITNESS};
 }
 
 //! Detect if type has a deserialize_type constructor, which is
@@ -170,96 +127,6 @@ decltype(auto) CustomReadField(TypeList<UniValue>, Priority<1>, InvokeContext& i
     });
 }
 
-//! Overload CustomBuildField and CustomReadField to serialize
-//! UniValue::type_error exceptions as text strings.
-template <typename Value, typename Output>
-void CustomBuildField(TypeList<UniValue::type_error>, Priority<1>, InvokeContext& invoke_context,
-                      Value&& value, Output&& output)
-{
-    BuildField(TypeList<std::string>(), invoke_context, output, std::string(value.what()));
-}
-
-template <typename Input, typename ReadDest>
-decltype(auto) CustomReadField(TypeList<UniValue::type_error>, Priority<1>, InvokeContext& invoke_context,
-                               Input&& input, ReadDest&& read_dest)
-{
-    read_dest.construct(ReadField(TypeList<std::string>(), invoke_context, input, mp::ReadDestTemp<std::string>()));
-}
-
-//! Overload CustomBuildField and CustomReadField to serialize util::Result
-//! return values as common.capnp Result and ResultVoid structs
-template <typename LocalType, typename Value, typename Output>
-void CustomBuildField(TypeList<util::Result<LocalType>>, Priority<1>, InvokeContext& invoke_context, Value&& value,
-                      Output&& output)
-{
-    auto result = output.init();
-    if (value) {
-        if constexpr (!std::is_same_v<LocalType, void>) {
-            using ValueAccessor = typename ProxyStruct<typename decltype(result)::Builds>::ValueAccessor;
-            BuildField(TypeList<LocalType>(), invoke_context, Make<StructField, ValueAccessor>(result), *value);
-        }
-    } else {
-        BuildField(TypeList<bilingual_str>(), invoke_context, Make<ValueField>(result.initError()),
-                   util::ErrorString(value));
-    }
-}
-
-template <typename LocalType, typename Input, typename ReadDest>
-decltype(auto) CustomReadField(TypeList<util::Result<LocalType>>, Priority<1>, InvokeContext& invoke_context,
-                               Input&& input, ReadDest&& read_dest)
-{
-    auto result = input.get();
-    if (result.hasError()) {
-        bilingual_str error;
-        ReadField(mp::TypeList<bilingual_str>(), invoke_context, mp::Make<mp::ValueField>(result.getError()),
-                    mp::ReadDestUpdate(error));
-        read_dest.construct(util::Error{std::move(error)});
-    } else {
-        if constexpr (!std::is_same_v<LocalType, void>) {
-            assert (result.hasValue());
-            ReadField(mp::TypeList<LocalType>(), invoke_context, mp::Make<mp::ValueField>(result.getValue()),
-                mp::ReadDestEmplace(
-                    mp::TypeList<LocalType>(), [&](auto&&... args) -> auto& {
-                        return *read_dest.construct(LocalType{std::forward<decltype(args)>(args)...});
-                    }));
-        } else {
-            read_dest.construct();
-        }
-    }
-}
-
-// libmultiprocess only provides read/build functions for std::set, not
-// std::unordered_set, so copy and paste those functions here.
-// TODO: Move these to libmultiprocess and dedup std::set, std::unordered_set,
-// and std::vector implementations.
-template <typename LocalType, typename Hash, typename Input, typename ReadDest>
-decltype(auto) CustomReadField(TypeList<std::unordered_set<LocalType, Hash>>, Priority<1>,
-                               InvokeContext& invoke_context, Input&& input, ReadDest&& read_dest)
-{
-    return read_dest.update([&](auto& value) {
-        auto data = input.get();
-        value.clear();
-        for (auto item : data) {
-            ReadField(TypeList<LocalType>(), invoke_context, Make<ValueField>(item),
-                      ReadDestEmplace(
-                          TypeList<const LocalType>(), [&](auto&&... args) -> auto& {
-                              return *value.emplace(std::forward<decltype(args)>(args)...).first;
-                          }));
-        }
-    });
-}
-
-template <typename LocalType, typename Hash, typename Value, typename Output>
-void CustomBuildField(TypeList<std::unordered_set<LocalType, Hash>>, Priority<1>, InvokeContext& invoke_context,
-                      Value&& value, Output&& output)
-{
-    auto list = output.init(value.size());
-    size_t i = 0;
-    for (const auto& elem : value) {
-        BuildField(TypeList<LocalType>(), invoke_context, ListOutput<typename decltype(list)::Builds>(list, i), elem);
-        ++i;
-    }
-}
 } // namespace mp
 
 #endif // BITCOIN_IPC_CAPNP_COMMON_TYPES_H
diff --git a/src/ipc/capnp/common.capnp b/src/ipc/capnp/common.capnp
index 2c14da5b8451..b3359f3f07b8 100644
--- a/src/ipc/capnp/common.capnp
+++ b/src/ipc/capnp/common.capnp
@@ -14,28 +14,3 @@ struct BlockRef $Proxy.wrap("interfaces::BlockRef") {
     hash @0 :Data;
     height @1 :Int32;
 }
-
-struct BilingualStr $Proxy.wrap("bilingual_str") {
-    original @0 :Text;
-    translated @1 :Text;
-}
-
-struct Result(Value) {
-    value @0 :Value;
-    error @1: BilingualStr;
-}
-
-# Wrapper for util::Result<void>
-struct ResultVoid(Value) {
-    error @0: BilingualStr;
-}
-
-struct Pair(Key, Value) {
-    key @0 :Key;
-    value @1 :Value;
-}
-
-struct PairInt64(Key) {
-    key @0 :Key;
-    value @1 :Int64;
-}
diff --git a/src/ipc/capnp/handler-types.h b/src/ipc/capnp/handler-types.h
deleted file mode 100644
index 9246a2df86a6..000000000000
--- a/src/ipc/capnp/handler-types.h
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright (c) 2025 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_IPC_CAPNP_HANDLER_TYPES_H
-#define BITCOIN_IPC_CAPNP_HANDLER_TYPES_H
-
-#include <mp/type-context.h>
-
-#endif // BITCOIN_IPC_CAPNP_HANDLER_TYPES_H
diff --git a/src/ipc/capnp/handler.capnp b/src/ipc/capnp/handler.capnp
deleted file mode 100644
index 1d3c7296acf2..000000000000
--- a/src/ipc/capnp/handler.capnp
+++ /dev/null
@@ -1,17 +0,0 @@
-# Copyright (c) 2021 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-@0xebd8f46e2f369076;
-
-using Cxx = import "/capnp/c++.capnp";
-$Cxx.namespace("ipc::capnp::messages");
-
-using Proxy = import "/mp/proxy.capnp";
-$Proxy.include("interfaces/handler.h");
-$Proxy.includeTypes("ipc/capnp/handler-types.h");
-
-interface Handler $Proxy.wrap("interfaces::Handler") {
-    destroy @0 (context :Proxy.Context) -> ();
-    disconnect @1 (context :Proxy.Context) -> ();
-}
diff --git a/src/ipc/capnp/init-types.h b/src/ipc/capnp/init-types.h
index d44cd2490807..c3ddca27c047 100644
--- a/src/ipc/capnp/init-types.h
+++ b/src/ipc/capnp/init-types.h
@@ -5,7 +5,6 @@
 #ifndef BITCOIN_IPC_CAPNP_INIT_TYPES_H
 #define BITCOIN_IPC_CAPNP_INIT_TYPES_H
 
-#include <ipc/capnp/chain.capnp.proxy-types.h>
 #include <ipc/capnp/echo.capnp.proxy-types.h>
 #include <ipc/capnp/mining.capnp.proxy-types.h>
 
diff --git a/src/ipc/capnp/init.capnp b/src/ipc/capnp/init.capnp
index 81469921e952..1001ee533687 100644
--- a/src/ipc/capnp/init.capnp
+++ b/src/ipc/capnp/init.capnp
@@ -8,13 +8,11 @@ using Cxx = import "/capnp/c++.capnp";
 $Cxx.namespace("ipc::capnp::messages");
 
 using Proxy = import "/mp/proxy.capnp";
-$Proxy.include("interfaces/chain.h");
 $Proxy.include("interfaces/echo.h");
 $Proxy.include("interfaces/init.h");
 $Proxy.include("interfaces/mining.h");
 $Proxy.includeTypes("ipc/capnp/init-types.h");
 
-using Chain = import "chain.capnp";
 using Echo = import "echo.capnp";
 using Mining = import "mining.capnp";
 
@@ -22,5 +20,4 @@ interface Init $Proxy.wrap("interfaces::Init") {
     construct @0 (threadMap: Proxy.ThreadMap) -> (threadMap :Proxy.ThreadMap);
     makeEcho @1 (context :Proxy.Context) -> (result :Echo.Echo);
     makeMining @2 (context :Proxy.Context) -> (result :Mining.Mining);
-    makeChain @3 (context :Proxy.Context) -> (result :Chain.Chain);
 }
diff --git a/src/ipc/capnp/mining.capnp b/src/ipc/capnp/mining.capnp
index 8ee4745b8584..14e1b2394721 100644
--- a/src/ipc/capnp/mining.capnp
+++ b/src/ipc/capnp/mining.capnp
@@ -19,6 +19,7 @@ interface Mining $Proxy.wrap("interfaces::Mining") {
     waitTipChanged @3 (context :Proxy.Context, currentTip: Data, timeout: Float64) -> (result: Common.BlockRef);
     createNewBlock @4 (options: BlockCreateOptions) -> (result: BlockTemplate);
     checkBlock @5 (block: Data, options: BlockCheckOptions) -> (reason: Text, debug: Text, result: Bool);
+    removeTxFromMempool @6 (context :Proxy.Context, txid :Data) -> (result :Bool);
 }
 
 interface BlockTemplate $Proxy.wrap("interfaces::BlockTemplate") {
diff --git a/src/node/interfaces.cpp b/src/node/interfaces.cpp
index f97adfc8b9aa..9bc0a14f73ed 100644
--- a/src/node/interfaces.cpp
+++ b/src/node/interfaces.cpp
@@ -553,19 +553,6 @@ class ChainImpl : public Chain
         LOCK(::cs_main);
         return Assert(chainman().ActiveChain()[height])->GetBlockHash();
     }
-    bool removeTxFromMempool(const uint256& txid) override
-    {
-        NodeContext& node = m_node;
-        if (!node.mempool) return false;
-        CTxMemPool& mempool = *node.mempool;
-        LOCK(mempool.cs);
-        CTransactionRef tx = mempool.get(txid);
-        if (tx) {
-            mempool.removeRecursive(*tx, MemPoolRemovalReason::MANUAL);
-            return true;
-        }
-        return false;
-    }
     bool haveBlockOnDisk(int height) override
     {
         LOCK(::cs_main);
@@ -834,7 +821,7 @@ class ChainImpl : public Chain
         return result;
     }
     bool updateRwSetting(const std::string& name,
-                         interfaces::SettingsUpdate update_settings_func) override
+                         const interfaces::SettingsUpdate& update_settings_func) override
     {
         std::optional<interfaces::SettingsAction> action;
         args().LockSettings([&](common::Settings& settings) {
@@ -1000,6 +987,20 @@ class MinerImpl : public Mining
         return state.IsValid();
     }
 
+    bool removeTxFromMempool(const uint256& txid) override
+    {
+        NodeContext& node = m_node;
+        if (!node.mempool) return false;
+        CTxMemPool& mempool = *node.mempool;
+        LOCK(mempool.cs);
+        CTransactionRef tx = mempool.get(txid);
+        if (tx) {
+            mempool.removeRecursive(*tx, MemPoolRemovalReason::MANUAL);
+            return true;
+        }
+        return false;
+    }
+
     NodeContext* context() override { return &m_node; }
     ChainstateManager& chainman() { return *Assert(m_node.chainman); }
     KernelNotifications& notifications() { return *Assert(m_node.notifications); }
diff --git a/src/rpc/request.h b/src/rpc/request.h
index 498b3bc6d6aa..2fb234c1973a 100644
--- a/src/rpc/request.h
+++ b/src/rpc/request.h
@@ -61,8 +61,6 @@ class JSONRPCRequest
     std::string peerAddr;
     std::any context;
     JSONRPCVersion m_json_version = JSONRPCVersion::V1_LEGACY;
-    // Note: If you add fields to this struct, you should also update the
-    // JSONRPCRequest struct in ipc/capnp/chain.capnp.
 
     void parse(const UniValue& valRequest);
     [[nodiscard]] bool IsNotification() const { return !id.has_value() && m_json_version == JSONRPCVersion::V2; };