Squashed 'src/ipc/libmultiprocess/' changes from 28e056576a..e8de5c7b68

diff --git a/doc/versions.md b/doc/versions.md
index 83b5cf53..35ae76bd 100644
--- a/doc/versions.md
+++ b/doc/versions.md
@@ -7,11 +7,12 @@ Library versions are tracked with simple
 Versioning policy is described in the [version.h](../include/mp/version.h)
 include.
 
-## v12
+## v13
 - Current unstable version.
-- Adds an optional per-listener `max_connections` parameter to `ListenConnections()`
-  so servers can stop accepting new connections when a local connection cap is reached,
-  and resume accepting after existing connections disconnect.
+
+## [v12.0](https://github.com/bitcoin-core/libmultiprocess/commits/v12.0)
+- Adds an optional `max_connections` parameter to `ListenConnections` ([#269](https://github.com/bitcoin-core/libmultiprocess/pull/269)).
+- Used in Bitcoin Core 32.x and newer releases with [#35684](https://github.com/bitcoin/bitcoin/pull/35684).
 
 ## [v11.0](https://github.com/bitcoin-core/libmultiprocess/commits/v11.0)
 - Adds `makePool` method on `ThreadMap` to support thread pool routing, allowing requests without a specific client thread to be dispatched to a pool using a shortest-queue strategy ([#283](https://github.com/bitcoin-core/libmultiprocess/pull/283)).
@@ -24,76 +25,79 @@ include.
 - Fixes a race condition in a log print detected by TSan ([#286](https://github.com/bitcoin-core/libmultiprocess/pull/286)).
 - Build improvements: makes `target_capnp_sources` work correctly when libmultiprocess is used as a CMake subproject ([#289](https://github.com/bitcoin-core/libmultiprocess/pull/289)), adds `mp_headers` target for better lint tool support ([#291](https://github.com/bitcoin-core/libmultiprocess/pull/291)), and fixes compatibility with recent Nix and CMake 4.0 ([#238](https://github.com/bitcoin-core/libmultiprocess/pull/238)).
 - Test, CI, documentation, and minor code improvements: design document corrections ([#278](https://github.com/bitcoin-core/libmultiprocess/pull/278)), field constant comments ([#279](https://github.com/bitcoin-core/libmultiprocess/pull/279)), clang-tidy fix ([#292](https://github.com/bitcoin-core/libmultiprocess/pull/292)), new smoke test for double-precision float values ([#294](https://github.com/bitcoin-core/libmultiprocess/pull/294)), new test for recursive async IPC calls ([#301](https://github.com/bitcoin-core/libmultiprocess/pull/301)), removal of libevent from Core CI builds ([#299](https://github.com/bitcoin-core/libmultiprocess/pull/299)), and rename of `EventLoop::m_num_clients` to `m_num_refs` ([#302](https://github.com/bitcoin-core/libmultiprocess/pull/302)).
-- Used in Bitcoin Core master branch, pulled in by [#35661](https://github.com/bitcoin/bitcoin/pull/35661).
+- Used in Bitcoin Core 32.x and newer releases with [#35661](https://github.com/bitcoin/bitcoin/pull/35661).
 
 ## [v10.0](https://github.com/bitcoin-core/libmultiprocess/commits/v10.0)
 - Increases spawn test timeout to avoid spurious failures.
 - Uses `throwRecoverableException` instead of raw `throw` to improve runtime error messages in macOS builds.
-- Used in Bitcoin Core master branch, pulled in by [#34977](https://github.com/bitcoin/bitcoin/pull/34977). Also pulled into Bitcoin Core 31.x stable branch by [#35028](https://github.com/bitcoin/bitcoin/pull/35028).
+- Used in Bitcoin Core 31.0rc3 and newer releases with [#34977](https://github.com/bitcoin/bitcoin/pull/34977) and backport [#35028](https://github.com/bitcoin/bitcoin/pull/35028).
 
 ## [v9.0](https://github.com/bitcoin-core/libmultiprocess/commits/v9.0)
 - Fixes race conditions where worker thread could be used after destruction, where getParams() could be called after request cancel, and where m_on_cancel could be called after request finishes.
 - Adds `CustomHasField` hook to map Cap'n Proto null values to C++ null values.
 - Improves `CustomBuildField` for `std::optional` to use move semantics.
 - Adds LLVM 22 compatibility fix in type-map.
-- Used in Bitcoin Core master branch, pulled in by [#34804](https://github.com/bitcoin/bitcoin/pull/34804). Also pulled into Bitcoin Core 31.x stable branch by [#34952](https://github.com/bitcoin/bitcoin/pull/34952).
+- Used in Bitcoin Core 31.0rc3 and newer releases with [#34804](https://github.com/bitcoin/bitcoin/pull/34804) and backport [#34952](https://github.com/bitcoin/bitcoin/pull/34952).
 
 ## [v8.0](https://github.com/bitcoin-core/libmultiprocess/commits/v8.0)
 - Better support for non-libmultiprocess IPC clients: avoiding errors on unclean disconnects, and allowing simultaneous requests to worker threads which previously triggered "thread busy" errors.
-- Intermediate version used in Bitcoin Core master branch between 30.x and 31.x branches, pulled in by [#34422](https://github.com/bitcoin/bitcoin/pull/34422).
+- Used in Bitcoin Core 31.x and newer releases with [#34422](https://github.com/bitcoin/bitcoin/pull/34422).
 
 ## [v7.0](https://github.com/bitcoin-core/libmultiprocess/commits/v7.0)
 - Adds SpawnProcess race fix, cmake `target_capnp_sources` option, ci and documentation improvements. Adds `version.h` header declaring major and minor version numbers.
-- Intermediate version used in Bitcoin Core master branch between 30.x and 31.x branches, pulled in by [#34363](https://github.com/bitcoin/bitcoin/pull/34363).
+- Used in Bitcoin Core 31.x and newer releases with [#34363](https://github.com/bitcoin/bitcoin/pull/34363).
 
 ## [v7.0-pre2](https://github.com/bitcoin-core/libmultiprocess/commits/v7.0-pre2)
 - Fixes intermittent mptest hang and makes other minor improvements.
-- Used in Bitcoin Core 30.1 and 30.2 releases and 30.x branch, pulled in by [#33518](https://github.com/bitcoin/bitcoin/pull/33518) and [#33519](https://github.com/bitcoin/bitcoin/pull/33519).
+- Used in Bitcoin Core 30.1 and newer releases with [#33518](https://github.com/bitcoin/bitcoin/pull/33518) and backport [#33519](https://github.com/bitcoin/bitcoin/pull/33519).
 
 ## [v7.0-pre1](https://github.com/bitcoin-core/libmultiprocess/commits/v7.0-pre1)
 - Adds support for log levels to reduce logging and "thread busy" error to avoid a crash on misuse.
-- Minimum required version since Bitcoin Core 30.1, pulled in by [#33412](https://github.com/bitcoin/bitcoin/pull/33412), [#33518](https://github.com/bitcoin/bitcoin/pull/33518), and [#33519](https://github.com/bitcoin/bitcoin/pull/33519).
+- Used in Bitcoin Core 30.1 and newer releases with [#33412](https://github.com/bitcoin/bitcoin/pull/33412) and [#33518](https://github.com/bitcoin/bitcoin/pull/33518) and backport [#33519](https://github.com/bitcoin/bitcoin/pull/33519).
+- Minimum required version since Bitcoin Core 30.1 due to [#33517](https://github.com/bitcoin/bitcoin/pull/33517) and backport [#33609](https://github.com/bitcoin/bitcoin/pull/33609).
 
 ## [v6.0](https://github.com/bitcoin-core/libmultiprocess/commits/v6.0)
 - Adds CI scripts and build and test fixes.
-- Used in Bitcoin Core 30.0 release, pulled in by [#32345](https://github.com/bitcoin/bitcoin/pull/32345), [#33241](https://github.com/bitcoin/bitcoin/pull/33241), and [#33322](https://github.com/bitcoin/bitcoin/pull/33322).
+- Used in Bitcoin Core 30.x and newer releases with [#32345](https://github.com/bitcoin/bitcoin/pull/32345), [#33241](https://github.com/bitcoin/bitcoin/pull/33241), and [#33322](https://github.com/bitcoin/bitcoin/pull/33322).
 
 ## [v6.0-pre1](https://github.com/bitcoin-core/libmultiprocess/commits/v6.0-pre1)
 - Adds fixes for unclean shutdowns and thread sanitizer issues.
 - Drops `EventLoop::addClient` and `EventLoop::removeClient` methods,
   requiring clients to use new `EventLoopRef` class instead.
-- Minimum required version for Bitcoin Core 30.0 release, pulled in by [#31741](https://github.com/bitcoin/bitcoin/pull/31741), [#32641](https://github.com/bitcoin/bitcoin/pull/32641), and [#32345](https://github.com/bitcoin/bitcoin/pull/32345).
+- Used in Bitcoin Core 30.x and newer releases with [#31741](https://github.com/bitcoin/bitcoin/pull/31741), [#32641](https://github.com/bitcoin/bitcoin/pull/32641), and [#32345](https://github.com/bitcoin/bitcoin/pull/32345).
+- Minimum required version since Bitcoin Core 30.0 due to [#32345](https://github.com/bitcoin/bitcoin/pull/32345).
 
 ## [v5.0](https://github.com/bitcoin-core/libmultiprocess/commits/v5.0)
 - Adds build improvements and tidy/warning fixes.
-- Used in Bitcoin Core 29 releases, pulled in by [#31945](https://github.com/bitcoin/bitcoin/pull/31945).
+- Used in Bitcoin Core 29.x and newer releases with [#31945](https://github.com/bitcoin/bitcoin/pull/31945).
 
 ## [v5.0-pre1](https://github.com/bitcoin-core/libmultiprocess/commits/v5.0-pre1)
 - Adds many improvements to Bitcoin Core mining interface: splitting up type headers, fixing shutdown bugs, adding subtree build support.
 - Broke up `proxy-types.h` into `type-*.h` files requiring clients to explicitly
   include overloads needed for C++ ↔️ Cap'n Proto type conversions.
 - Now requires C++ 20 support.
-- Minimum required version for Bitcoin Core 29 releases, pulled in by [#30509](https://github.com/bitcoin/bitcoin/pull/30509), [#30510](https://github.com/bitcoin/bitcoin/pull/30510), [#31105](https://github.com/bitcoin/bitcoin/pull/31105), [#31740](https://github.com/bitcoin/bitcoin/pull/31740).
+- Used in Bitcoin Core 29.x and newer releases with [#30509](https://github.com/bitcoin/bitcoin/pull/30509), [#30510](https://github.com/bitcoin/bitcoin/pull/30510), [#31105](https://github.com/bitcoin/bitcoin/pull/31105), [#31740](https://github.com/bitcoin/bitcoin/pull/31740).
+- Minimum required version since Bitcoin Core 29.0 due to [#31740](https://github.com/bitcoin/bitcoin/pull/31740).
 
 ## [v4.0](https://github.com/bitcoin-core/libmultiprocess/commits/v4.0)
 - Added better cmake support, installing cmake package files so clients do not
   need to use pkgconfig.
-- Used in Bitcoin Core 28 releases, pulled in by [#30490](https://github.com/bitcoin/bitcoin/pull/30490) and [#30513](https://github.com/bitcoin/bitcoin/pull/30513).
+- Used in Bitcoin Core 28.x and newer releases with [#30490](https://github.com/bitcoin/bitcoin/pull/30490) and [#30513](https://github.com/bitcoin/bitcoin/pull/30513).
 
 ## [v3.0](https://github.com/bitcoin-core/libmultiprocess/commits/v3.0)
 - Dropped compatibility with Cap'n Proto versions before 0.7.
-- Used in Bitcoin Core 27 releases, pulled in by [#28735](https://github.com/bitcoin/bitcoin/pull/28735), [#28907](https://github.com/bitcoin/bitcoin/pull/28907), and [#29276](https://github.com/bitcoin/bitcoin/pull/29276).
+- Used in Bitcoin Core 27.x and newer releases with [#28735](https://github.com/bitcoin/bitcoin/pull/28735), [#28907](https://github.com/bitcoin/bitcoin/pull/28907), and [#29276](https://github.com/bitcoin/bitcoin/pull/29276).
 
 ## [v2.0](https://github.com/bitcoin-core/libmultiprocess/commits/v2.0)
 - Changed `PassField` function signature.
 - Now requires C++17 support.
-- Used in Bitcoin Core 25 and 26 releases, pulled in by [#26672](https://github.com/bitcoin/bitcoin/pull/26672).
+- Used in Bitcoin Core 25.x and newer releases with [#26672](https://github.com/bitcoin/bitcoin/pull/26672).
 
 ## [v1.0](https://github.com/bitcoin-core/libmultiprocess/commits/v1.0)
 - Dropped hardcoded includes in generated files, now requiring `include` and
   `includeTypes` annotations.
-- Used in Bitcoin Core 22, 23, and 24 releases, pulled in by [#19160](https://github.com/bitcoin/bitcoin/pull/19160).
+- Used in Bitcoin Core 22.x and newer releases with [#19160](https://github.com/bitcoin/bitcoin/pull/19160).
 
 ## [v0.0](https://github.com/bitcoin-core/libmultiprocess/commits/v0.0)
 - Initial version used in a downstream release.
-- Used in Bitcoin Core 21 releases, pulled in by [#16367](https://github.com/bitcoin/bitcoin/pull/16367), [#18588](https://github.com/bitcoin/bitcoin/pull/18588), and [#18677](https://github.com/bitcoin/bitcoin/pull/18677).
+- Used in Bitcoin Core 21.x and newer releases with [#16367](https://github.com/bitcoin/bitcoin/pull/16367), [#18588](https://github.com/bitcoin/bitcoin/pull/18588), and [#18677](https://github.com/bitcoin/bitcoin/pull/18677).
diff --git a/include/mp/type-data.h b/include/mp/type-data.h
index cdcdd30e..09c93df9 100644
--- a/include/mp/type-data.h
+++ b/include/mp/type-data.h
@@ -9,6 +9,7 @@
 
 #include <concepts>
 #include <span>
+#include <ranges>
 
 namespace mp {
 template <typename T, typename U>
@@ -33,7 +34,7 @@ requires (std::is_same_v<decltype(output.get()), ::capnp::Data::Builder> && IsBy
 {
     auto data = std::span{value};
     auto result = output.init(data.size());
-    memcpy(result.begin(), data.data(), data.size());
+    std::ranges::copy(data, result.begin());
 }
 
 template <typename LocalType, typename Input, typename ReadDest>
diff --git a/include/mp/version.h b/include/mp/version.h
index 4587a288..bbf54524 100644
--- a/include/mp/version.h
+++ b/include/mp/version.h
@@ -24,7 +24,7 @@
 //! pointing at the prior merge commit. The /doc/versions.md file should also be
 //! updated, noting any significant or incompatible changes made since the
 //! previous version.
-#define MP_MAJOR_VERSION 12
+#define MP_MAJOR_VERSION 13
 
 //! Minor version number. Should be incremented in stable branches after
 //! backporting changes. The /doc/versions.md file should also be updated to
diff --git a/test/mp/test/foo.capnp b/test/mp/test/foo.capnp
index 31736452..9e6213fd 100644
--- a/test/mp/test/foo.capnp
+++ b/test/mp/test/foo.capnp
@@ -27,6 +27,7 @@ interface FooInterface $Proxy.wrap("mp::test::FooImplementation") {
     callbackExtended @10 (context :Proxy.Context, callback :ExtendedCallback, arg: Int32) -> (result :Int32);
     passCustom @11 (arg :FooCustom) -> (result :FooCustom);
     passEmpty @12 (arg :FooEmpty) -> (result :FooEmpty);
+    passData @24 (arg :Data) -> (result :Data);
     passMessage @13 (arg :FooMessage) -> (result :FooMessage);
     passMutable @14 (arg :FooMutable) -> (arg :FooMutable);
     passEnum @15 (arg :Int32) -> (result :Int32);
@@ -55,10 +56,11 @@ interface FooFn $Proxy.wrap("ProxyCallback<std::function<int()>>") {
 struct FooStruct $Proxy.wrap("mp::test::FooStruct") {
     name @0 :Text;
     setInt @1 :List(Int32) $Proxy.name("set_int");
-    vBool @2 :List(Bool) $Proxy.name("v_bool");
+    vectorBool @2 :List(Bool) $Proxy.name("vector_bool");
     optionalInt @3 :Int32 $Proxy.name("optional_int");
     hasOptionalInt @4 :Bool;
     unorderedSetInt @5 :List(Int32) $Proxy.name("unordered_set_int");
+    mapStringInt @6 :List(StringIntPair) $Proxy.name("map_string_int");
 }
 
 struct FooCustom $Proxy.wrap("mp::test::FooCustom") {
@@ -81,3 +83,8 @@ struct Pair(T1, T2) {
     first @0 :T1;
     second @1 :T2;
 }
+
+struct StringIntPair {
+    first @0 :Text;
+    second @1 :Int32;
+}
diff --git a/test/mp/test/foo.h b/test/mp/test/foo.h
index 5b66b85e..779c8db1 100644
--- a/test/mp/test/foo.h
+++ b/test/mp/test/foo.h
@@ -22,9 +22,10 @@ struct FooStruct
 {
     std::string name;
     std::set<int> set_int;
-    std::vector<bool> v_bool;
+    std::vector<bool> vector_bool;
     std::optional<int> optional_int;
     std::unordered_set<int> unordered_set_int;
+    std::map<std::string, int> map_string_int;
 };
 
 enum class FooEnum : uint8_t { ONE = 1, TWO = 2, };
@@ -83,6 +84,7 @@ public:
     int callbackExtended(ExtendedCallback& callback, int arg) { return callback.callExtended(arg); }
     FooCustom passCustom(FooCustom foo) { return foo; }
     FooEmpty passEmpty(FooEmpty foo) { return foo; }
+    FooData passData(FooData foo) { return foo; }
     FooMessage passMessage(FooMessage foo) { foo.message += " call"; return foo; }
     void passMutable(FooMutable& foo) { foo.message += " call"; }
     FooEnum passEnum(FooEnum foo) { return foo; }
diff --git a/test/mp/test/test.cpp b/test/mp/test/test.cpp
index 1fc30691..7a0940c8 100644
--- a/test/mp/test/test.cpp
+++ b/test/mp/test/test.cpp
@@ -23,6 +23,7 @@
 #include <kj/memory.h>
 #include <kj/string.h>
 #include <kj/test.h>
+#include <map>
 #include <memory>
 #include <mp/proxy.h>
 #include <mp/proxy.capnp.h>
@@ -157,10 +158,12 @@ KJ_TEST("Call FooInterface methods")
     in.set_int.insert(1);
     in.unordered_set_int.insert(2);
     in.unordered_set_int.insert(1);
-    in.v_bool.push_back(false);
-    in.v_bool.push_back(true);
-    in.v_bool.push_back(false);
+    in.vector_bool.push_back(false);
+    in.vector_bool.push_back(true);
+    in.vector_bool.push_back(false);
     in.optional_int = 3;
+    in.map_string_int.emplace("a", 1);
+    in.map_string_int.emplace("b", 2);
     FooStruct out = foo->pass(in);
     KJ_EXPECT(in.name == out.name);
     KJ_EXPECT(in.set_int.size() == out.set_int.size());
@@ -171,11 +174,16 @@ KJ_TEST("Call FooInterface methods")
     for (const auto& elem : in.unordered_set_int) {
         KJ_EXPECT(out.unordered_set_int.count(elem) == 1);
     }
-    KJ_EXPECT(in.v_bool.size() == out.v_bool.size());
-    for (size_t i = 0; i < in.v_bool.size(); ++i) {
-        KJ_EXPECT(in.v_bool[i] == out.v_bool[i]);
+    KJ_EXPECT(in.vector_bool.size() == out.vector_bool.size());
+    for (size_t i = 0; i < in.vector_bool.size(); ++i) {
+        KJ_EXPECT(in.vector_bool[i] == out.vector_bool[i]);
     }
     KJ_EXPECT(in.optional_int == out.optional_int);
+    KJ_EXPECT(in.map_string_int.size() == out.map_string_int.size());
+    for (auto init{in.map_string_int.begin()}, outit{out.map_string_int.begin()}; init != in.map_string_int.end() && outit != out.map_string_int.end(); ++init, ++outit) {
+        KJ_EXPECT(init->first == outit->first);
+        KJ_EXPECT(init->second == outit->second);
+    }
 
     // Additional checks for std::optional member
     KJ_EXPECT(foo->pass(in).optional_int == 3);
@@ -231,6 +239,9 @@ KJ_TEST("Call FooInterface methods")
 
     foo->passEmpty(FooEmpty{});
 
+    FooData empty_data_out = foo->passData(FooData{});
+    KJ_EXPECT(empty_data_out.empty());
+
     FooMessage message1;
     message1.message = "init";
     FooMessage message2{foo->passMessage(message1)};