diff --git a/Makefile b/Makefile
index 768395d0..92d18709 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ SANITIZERS := run
 #     SANITIZERS += asan # TODO: tsan msan
 # endif
 
-.PHONY: default release debug doc run update check ce todo distclean clean codespell clang-tidy build test install all format unstage $(SANITIZERS)
+.PHONY: default release debug doc run update check ce todo distclean clean codespell clang-tidy build test install all format unstage $(SANITIZERS) module build-module test-module
 
 SYSROOT   ?=
 TOOLCHAIN ?=
@@ -134,6 +134,22 @@ build:
 test: build
 	ctest --test-dir $(BUILD) --rerun-failed --output-on-failure
 
+module build-module:
+	cmake -G Ninja -S $(SOURCEDIR) -B $(BUILD) $(TOOLCHAIN) $(SYSROOT) \
+	  -D CMAKE_EXPORT_COMPILE_COMMANDS=ON \
+	  -D CMAKE_SKIP_INSTALL_RULES=ON \
+	  -D CMAKE_CXX_STANDARD=23 \
+	  -D CMAKE_CXX_EXTENSIONS=ON \
+	  -D CMAKE_CXX_STANDARD_REQUIRED=ON \
+	  -D CMAKE_CXX_SCAN_FOR_MODULES=ON \
+	  -D BEMAN_USE_MODULES=ON \
+	  -D CMAKE_BUILD_TYPE=Release \
+	  -D CMAKE_CXX_COMPILER=$(CXX) --log-level=VERBOSE
+	cmake --build $(BUILD)
+
+test-module: build-module
+	ctest --test-dir $(BUILD) --rerun-failed --output-on-failure
+
 install: test
 	cmake --install $(BUILD) --prefix /opt/local
 
@@ -141,13 +157,13 @@ CMakeUserPresets.json:: cmake/CMakeUserPresets.json
 	ln -s $< $@
 
 # ==========================================================
-release: CMakeUserPresets.json
+appleclang-release llvm-release release: #-dk: I'm not sure why that is needed: CMakeUserPresets.json
 	cmake --preset $@ --log-level=TRACE # XXX --fresh
 	ln -fs $(BUILDROOT)/$@/compile_commands.json .
 	cmake --workflow --preset $@
 
 # ==========================================================
-debug: CMakeUserPresets.json
+appleclang-debug llvm-debug debug: #-dk: I'm not sure why that is needed: CMakeUserPresets.json
 	cmake --preset $@ --log-level=TRACE # XXX --fresh
 	ln -fs $(BUILDROOT)build/$@/compile_commands.json .
 	cmake --workflow --preset $@
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 71ffabca..464d782f 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -18,31 +18,33 @@ if(PROJECT_IS_TOP_LEVEL)
 endif()
 
 set(EXAMPLES
-    stackoverflow
+    allocator
+    doc-just
+    doc-just_error
+    doc-just_stopped
     inspect
+    intro-1-hello-world
+    intro-2-hello-async
+    intro-5-consumer
     playground
     sender-demo
-    when_all-cancel
+    stackoverflow
     stop_token
     stopping
-    allocator
-    intro-1-hello-world
-    intro-2-hello-async
-    intro-5-consumer
-    doc-just
-    doc-just_error
-    doc-just_stopped
+    when_all-cancel
 )
 
 if(BEMAN_USE_MODULES)
     list(APPEND EXAMPLES modules) # modules.cpp
 endif()
+# set(EXAMPLES)
 
 foreach(EXAMPLE ${EXAMPLES})
     set(EXAMPLE_TARGET ${PROJECT_NAME}.${EXAMPLE})
     add_executable(${EXAMPLE_TARGET})
     target_sources(${EXAMPLE_TARGET} PRIVATE ${EXAMPLE}.cpp)
     if(BEMAN_USE_MODULES)
+        # target_compile_definitions(${EXAMPLE_TARGET} PUBLIC BEMAN_HAS_MODULES)
         target_link_libraries(${EXAMPLE_TARGET} PRIVATE beman::execution)
     else()
         target_link_libraries(
diff --git a/examples/allocator.cpp b/examples/allocator.cpp
index 845275ff..3c00ed07 100644
--- a/examples/allocator.cpp
+++ b/examples/allocator.cpp
@@ -1,10 +1,17 @@
-#include <beman/execution/execution.hpp>
+// examples/allocator.cpp                                             -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
 #include <iostream>
 #include <string>
 #include <memory>
 #include <memory_resource>
 #include <span>
 #include <vector>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = beman::execution;
 
diff --git a/examples/doc-just.cpp b/examples/doc-just.cpp
index a63c2d59..d25ded01 100644
--- a/examples/doc-just.cpp
+++ b/examples/doc-just.cpp
@@ -1,9 +1,13 @@
 // examples/doc-just.cpp                                              -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <cassert>
 #include <string>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 namespace ex = beman::execution;
 using namespace std::string_literals;
 
diff --git a/examples/doc-just_error.cpp b/examples/doc-just_error.cpp
index c347485b..7acba327 100644
--- a/examples/doc-just_error.cpp
+++ b/examples/doc-just_error.cpp
@@ -1,9 +1,13 @@
 // examples/doc-just_error.cpp                                        -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <system_error>
 #include <cassert>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 namespace ex = beman::execution;
 
 namespace {
diff --git a/examples/doc-just_stopped.cpp b/examples/doc-just_stopped.cpp
index 60c854e9..b4fe76f0 100644
--- a/examples/doc-just_stopped.cpp
+++ b/examples/doc-just_stopped.cpp
@@ -1,10 +1,13 @@
 // examples/doc-just_stopped.cpp                                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <system_error>
 #include <cassert>
-#include <iostream> //-dk:TODO remove
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 namespace ex = beman::execution;
 
 namespace {
diff --git a/examples/inspect.cpp b/examples/inspect.cpp
index e6fcd470..366a6be1 100644
--- a/examples/inspect.cpp
+++ b/examples/inspect.cpp
@@ -1,16 +1,138 @@
 // examples/inspectc.pp                                               -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
-#include "meta.hpp"
 #include <iostream>
+#include <ostream>
 #include <sstream>
+#include <string>
 #include <typeinfo>
+#include <tuple>
+#include <variant>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = beman::execution;
 
 // ----------------------------------------------------------------------------
 
+namespace meta {
+// The code in this namespace is a fairly basic way to print types. It can
+// almost certainly be done better, in particular using reflection. However,
+// that's beside the point of this example. The important part for the
+// example is that meta::type<T>::name() yields a string representing the
+// type T in some reasonable way
+template <template <typename...> class, typename...>
+struct list {
+    static auto name() { return "unknown-list"; }
+};
+template <>
+struct list<::beman::execution::completion_signatures> {
+    static auto name() { return "ex::completion_signatures"; }
+};
+
+template <typename T>
+struct type {
+    static auto name() { return typeid(T).name(); }
+};
+template <typename T>
+struct type<T&> {
+    static auto name() { return typeid(T).name() + std::string("&"); }
+};
+template <typename T>
+struct type<T&&> {
+    static auto name() { return typeid(T).name() + std::string("&&"); }
+};
+template <typename T>
+struct type<T*> {
+    static auto name() { return typeid(T).name() + std::string("*"); }
+};
+template <typename T>
+struct type<const T> {
+    static auto name() { return typeid(T).name() + std::string("const"); }
+};
+template <typename T>
+struct type<volatile T> {
+    static auto name() { return typeid(T).name() + std::string("volatile"); }
+};
+template <typename T>
+struct type<const volatile T> {
+    static auto name() { return typeid(T).name() + std::string("const volatile"); }
+};
+// NOLINTBEGIN(hicpp-avoid-c-arrays)
+template <typename T, std::size_t N>
+struct type<T[N]> {
+    static auto name() { return typeid(T).name() + std::string("[") + std::to_string(N) + "]"; }
+};
+template <typename T, std::size_t N>
+struct type<T (&)[N]> {
+    static auto name() { return typeid(T).name() + std::string("(&)[") + std::to_string(N) + "]"; }
+};
+template <typename T, std::size_t N>
+struct type<T (*)[N]> {
+    static auto name() { return typeid(T).name() + std::string("(*)[") + std::to_string(N) + "]"; }
+};
+// NOLINTEND(hicpp-avoid-c-arrays)
+
+template <>
+struct type<::beman::execution::set_value_t> {
+    static auto name() { return "ex::set_value_t"; }
+};
+template <>
+struct type<::beman::execution::set_error_t> {
+    static auto name() { return "ex::set_error_t"; }
+};
+template <>
+struct type<::beman::execution::set_stopped_t> {
+    static auto name() { return "ex::set_stopped_t"; }
+};
+
+template <typename T>
+struct type<T()> {
+    static auto name() { return type<T>::name() + std::string("()"); }
+};
+template <typename T, typename A, typename... B>
+struct type<T(A, B...)> {
+    static auto name() {
+        return type<T>::name() + std::string("(") + (type<A>::name() + ... + (std::string(", ") + type<B>::name())) +
+               ")";
+    }
+};
+template <typename T>
+struct type<T (*)()> {
+    static auto name() { return type<T>::name() + std::string("(*)()"); }
+};
+template <typename T, typename A, typename... B>
+struct type<T (*)(A, B...)> {
+    static auto name() {
+        return type<T>::name() + std::string("(*)(") +
+               (type<A>::name() + ... + (std::string(", ") + type<B>::name())) + ")";
+    }
+};
+
+template <template <typename...> class L>
+struct type<L<>> {
+    static auto name() { return list<L>::name() + std::string("<>"); }
+};
+
+template <template <typename...> class L, typename T, typename... S>
+struct type<L<T, S...>> {
+    static auto name() {
+        return list<L>::name() + std::string("<") + (type<T>::name() + ... + (std::string(", ") + type<S>::name())) +
+               ">";
+    }
+};
+
+template <typename T>
+inline std::ostream& operator<<(std::ostream& out, const type<T>& t) {
+    return out << t.name();
+}
+} // namespace meta
+
+// ----------------------------------------------------------------------------
+
 namespace {
 struct logger_t {
     template <ex::sender Sndr, ex::receiver Rcvr, typename Log>
diff --git a/examples/intro-1-hello-world.cpp b/examples/intro-1-hello-world.cpp
index 87cb8d70..92fb6bc7 100644
--- a/examples/intro-1-hello-world.cpp
+++ b/examples/intro-1-hello-world.cpp
@@ -1,10 +1,16 @@
 // examples/intro-1-hello-world.cpp                                   -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <iostream>
+#include <optional>
 #include <string>
 #include <tuple>
+#include <variant>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = ::beman::execution;
 using namespace std::string_literals;
@@ -14,13 +20,14 @@ using namespace std::string_literals;
 
 int main() {
     // clang-format off
-     auto [result] = ex::sync_wait(
-         ex::when_all(
-             ex::just("hello, "s),
-             ex::just("world"s)
-         ) | ex::then([](auto const& s1, auto const& s2) { return s1 + s2; })
-         ).value_or(std::tuple(""s)
-     );
+    auto [result] =
+    ex::sync_wait(
+        ex::when_all(
+            ex::just("hello, "s),
+            ex::just("world"s)
+        ) | ex::then([](auto const& s1, auto const& s2) { return s1 + s2; })
+        ) .value_or(std::tuple(""s))
+        ;
     // clang-format on
 
     std::cout << result << '\n';
diff --git a/examples/intro-2-hello-async.cpp b/examples/intro-2-hello-async.cpp
index 7809160c..58483a0d 100644
--- a/examples/intro-2-hello-async.cpp
+++ b/examples/intro-2-hello-async.cpp
@@ -1,12 +1,18 @@
 // examples/intro-2-hello-async.cpp                                   -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
-#include "intro-timer.hpp"
 #include <chrono>
 #include <iostream>
+#include <queue>
 #include <string>
+#include <thread>
 #include <tuple>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
+#include "intro-timer.hpp"
 
 namespace ex = ::beman::execution;
 using namespace std::string_literals;
diff --git a/examples/intro-5-consumer.cpp b/examples/intro-5-consumer.cpp
index 2b2df822..126e3a27 100644
--- a/examples/intro-5-consumer.cpp
+++ b/examples/intro-5-consumer.cpp
@@ -1,7 +1,6 @@
 // examples/intro-5-consumer.cpp                                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <beman/execution/detail/suppress_push.hpp>
 #include <chrono>
 //-dk:TODO restore if that actually works #include <expected>
@@ -10,6 +9,11 @@
 #include <tuple>
 #include <variant>
 #include <cinttypes>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = ::beman::execution;
 using namespace std::string_literals;
diff --git a/examples/intro-timer.hpp b/examples/intro-timer.hpp
index a81ffe6e..6442e24d 100644
--- a/examples/intro-timer.hpp
+++ b/examples/intro-timer.hpp
@@ -1,17 +1,9 @@
 // examples/intro-timer.hpp                                           -*-C++-*-
-// ----------------------------------------------------------------------------
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-// ----------------------------------------------------------------------------
 
 #ifndef INCLUDED_EXAMPLES_INTRO_TIMER
 #define INCLUDED_EXAMPLES_INTRO_TIMER
 
-#include <beman/execution/execution.hpp>
-#include <chrono>
-#include <queue>
-#include <thread>
-#include <tuple>
-
 // ----------------------------------------------------------------------------
 
 namespace intro {
diff --git a/examples/just_stopped.cpp b/examples/just_stopped.cpp
index ad0c668a..fe0baee0 100644
--- a/examples/just_stopped.cpp
+++ b/examples/just_stopped.cpp
@@ -1,3 +1,6 @@
+// examples/just_stopped.cpp                                          -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
 #include <beman/execution/execution.hpp>
 namespace ex = beman::execution;
 
diff --git a/examples/meta.hpp b/examples/meta.hpp
index 96d8d4d6..3f6a04ca 100644
--- a/examples/meta.hpp
+++ b/examples/meta.hpp
@@ -4,11 +4,6 @@
 #ifndef INCLUDED_EXAMPLES_META
 #define INCLUDED_EXAMPLES_META
 
-#include <beman/execution/execution.hpp>
-#include <ostream>
-#include <string>
-#include <typeinfo>
-
 // ----------------------------------------------------------------------------
 
 namespace meta {
diff --git a/examples/modules.cpp b/examples/modules.cpp
index a86f861c..ea400d62 100644
--- a/examples/modules.cpp
+++ b/examples/modules.cpp
@@ -14,7 +14,7 @@ import std;
 
 #endif
 
-#ifdef BEMAN_USE_MODULES
+#ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
diff --git a/examples/playground.cpp b/examples/playground.cpp
index c4ea5220..f62cdea9 100644
--- a/examples/playground.cpp
+++ b/examples/playground.cpp
@@ -1,10 +1,15 @@
 // examples/playground.cpp                                            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <iostream>
 #include <string>
 #include <tuple>
+#include <variant>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = ::beman::execution;
 
diff --git a/examples/sender-demo.cpp b/examples/sender-demo.cpp
index d9ac194e..6f4c1aa3 100644
--- a/examples/sender-demo.cpp
+++ b/examples/sender-demo.cpp
@@ -1,9 +1,17 @@
-#include <beman/execution/execution.hpp>
-#include <type_traits>
-#include <string>
+// examples/sender-demo.cpp                                           -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <iostream>
 #include <memory_resource>
+#include <string>
+#include <type_traits>
 #include <utility>
-#include <iostream>
+#include <variant>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = beman::execution;
 
@@ -50,8 +58,8 @@ int main() {
         auto j = just_sender<std::pmr::string>{std::pmr::string("value")};
         auto t = std::move(j) | ex::then([](const std::pmr::string& v) { return v + " then"; });
         auto w = ex::when_all(std::move(t));
-        auto e = ex::detail::write_env(std::move(w),
-                                       ex::detail::make_env(ex::get_allocator, std::pmr::polymorphic_allocator<>()));
+        auto e =
+            ex::write_env(std::move(w), ex::detail::make_env(ex::get_allocator, std::pmr::polymorphic_allocator<>()));
 
         std::cout << "before start\n";
         auto r = ex::sync_wait(std::move(e));
diff --git a/examples/stackoverflow.cpp b/examples/stackoverflow.cpp
index b243fdee..617e2f2d 100644
--- a/examples/stackoverflow.cpp
+++ b/examples/stackoverflow.cpp
@@ -1,8 +1,16 @@
-#include <beman/execution/execution.hpp>
+// examples/allocator.cpp                                             -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
 #include <coroutine>
 #include <iostream>
+#include <memory>
 #include <type_traits>
 #include <utility>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 namespace ex = beman::execution;
 
diff --git a/examples/stop_token.cpp b/examples/stop_token.cpp
index fe9b467c..eb546678 100644
--- a/examples/stop_token.cpp
+++ b/examples/stop_token.cpp
@@ -1,13 +1,18 @@
 // examples/stop_token.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/stop_token.hpp>
 #include <condition_variable>
 #include <iostream>
 #include <exception>
 #include <latch>
 #include <mutex>
 #include <thread>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#include <beman/execution/stop_token.hpp>
+#endif
 
 namespace exec = beman::execution;
 
diff --git a/examples/stopping.cpp b/examples/stopping.cpp
index 86a92fa4..f4c8fd43 100644
--- a/examples/stopping.cpp
+++ b/examples/stopping.cpp
@@ -6,12 +6,16 @@
 // which gets started in a thread. To stop this thread
 // the corresponding stop source is requested to stop.
 
-#include <beman/execution/execution.hpp>
-#include <beman/execution/stop_token.hpp>
 #include <chrono>
 #include <iostream>
 #include <thread>
 #include <cassert>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#include <beman/execution/stop_token.hpp>
+#endif
 
 using namespace std::chrono;
 namespace ex = beman::execution;
diff --git a/examples/when_all-cancel.cpp b/examples/when_all-cancel.cpp
index 8fd3c6e3..eb445498 100644
--- a/examples/when_all-cancel.cpp
+++ b/examples/when_all-cancel.cpp
@@ -1,13 +1,21 @@
 // examples/when_all-cancel.cpp                                       -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
-#include <beman/execution/stop_token.hpp>
+#include <exception>
 #include <iostream>
 #include <optional>
+#include <string>
+#include <tuple>
 #include <type_traits>
 #include <utility>
+#include <variant>
 #include <cassert>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#include <beman/execution/stop_token.hpp>
+#endif
 
 namespace ex = beman::execution;
 
diff --git a/include/beman/execution/detail/affine_on.hpp b/include/beman/execution/detail/affine_on.hpp
index 45a3ea15..44078900 100644
--- a/include/beman/execution/detail/affine_on.hpp
+++ b/include/beman/execution/detail/affine_on.hpp
@@ -34,6 +34,19 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
+template <typename Ev>
+struct affine_on_env {
+    Ev   ev_;
+    auto query(const ::beman::execution::get_stop_token_t&) const noexcept -> ::beman::execution::never_stop_token {
+        return ::beman::execution::never_stop_token();
+    }
+    template <typename Q>
+    auto query(const Q& q) const noexcept -> decltype(q(this->ev_)) {
+        return q(this->ev_);
+    }
+};
+template <typename Ev>
+affine_on_env(const Ev&) -> affine_on_env<Ev>;
 
 /**
  * @brief The affine_on_t struct is a sender adaptor closure that transforms a sender
@@ -66,21 +79,6 @@ struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
      */
     auto operator()() const { return ::beman::execution::detail::sender_adaptor{*this}; }
 
-    template <typename Ev>
-    struct ao_env {
-        Ev   ev_;
-        auto query(const ::beman::execution::get_stop_token_t&) const noexcept
-            -> ::beman::execution::never_stop_token {
-            return ::beman::execution::never_stop_token();
-        }
-        template <typename Q>
-        auto query(const Q& q) const noexcept -> decltype(q(this->ev_)) {
-            return q(this->ev_);
-        }
-    };
-    template <typename Ev>
-    ao_env(const Ev&) -> ao_env<Ev>;
-
     /**
      * @brief affine_on is implemented by transforming it into a use of schedule_from.
      *
@@ -124,7 +122,7 @@ struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
                 ::beman::execution::schedule_from(
                     ::beman::execution::get_scheduler(ev),
                     ::beman::execution::write_env(::beman::execution::detail::forward_like<Sender>(child), ev)),
-                ao_env(ev));
+                beman::execution::detail::affine_on_env(ev));
         }
     }
 };
diff --git a/include/beman/execution/detail/apply_sender.hpp b/include/beman/execution/detail/apply_sender.hpp
index 55ab8cf1..2cc63a66 100644
--- a/include/beman/execution/detail/apply_sender.hpp
+++ b/include/beman/execution/detail/apply_sender.hpp
@@ -29,7 +29,7 @@ constexpr auto apply_sender(Domain domain, Tag, Sender&& sender, Args&&... args)
  * \brief Default function used to transform a second and its arguments.
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  */
-template <typename Domain, typename Tag, ::beman::execution::sender Sender, typename... Args>
+BEMAN_EXECUTION_EXPORT template <typename Domain, typename Tag, ::beman::execution::sender Sender, typename... Args>
     requires(not requires(Domain domain, Tag tag, Sender&& sender, Args&&... args) {
                 domain.apply_sender(Tag(), ::std::forward<Sender>(sender), ::std::forward<Args>(args)...);
             }) && requires(Tag tag, Sender&& sender, Args&&... args) {
diff --git a/include/beman/execution/detail/associate.hpp b/include/beman/execution/detail/associate.hpp
index d7413610..33d89713 100644
--- a/include/beman/execution/detail/associate.hpp
+++ b/include/beman/execution/detail/associate.hpp
@@ -21,7 +21,8 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
+BEMAN_EXECUTION_EXPORT template <::beman::execution::scope_token Token,
+                                 ::beman::execution::sender      Sender> //-dk:TODO detail export
 struct associate_data {
     using wrap_sender = ::std::remove_cvref_t<decltype(::std::declval<Token&>().wrap(::std::declval<Sender>()))>;
 
@@ -64,7 +65,7 @@ struct associate_data {
     Token                        token;
     ::std::optional<wrap_sender> sender;
 };
-template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
+BEMAN_EXECUTION_EXPORT template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
 associate_data(Token, Sender&&) -> associate_data<Token, Sender>;
 
 struct associate_t {
diff --git a/include/beman/execution/detail/await_result_type.hpp b/include/beman/execution/detail/await_result_type.hpp
index 51f82439..6de785d1 100644
--- a/include/beman/execution/detail/await_result_type.hpp
+++ b/include/beman/execution/detail/await_result_type.hpp
@@ -16,7 +16,7 @@ namespace beman::execution::detail {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-template <typename T, typename Promise>
+BEMAN_EXECUTION_EXPORT template <typename T, typename Promise> //-dk:TODO detail export
 using await_result_type =
     decltype(::beman::execution::detail::get_awaiter(::std::declval<T>(), ::std::declval<Promise&>()).await_resume());
 } // namespace beman::execution::detail
diff --git a/include/beman/execution/detail/basic_operation.hpp b/include/beman/execution/detail/basic_operation.hpp
index be78f56b..fd6f8d1a 100644
--- a/include/beman/execution/detail/basic_operation.hpp
+++ b/include/beman/execution/detail/basic_operation.hpp
@@ -25,7 +25,8 @@ namespace beman::execution::detail {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-template <typename Sender, typename Receiver>
+//-dk:TODO the export below shouldn't be needed, but MSVC++ seems to require it (2026-02-01)
+BEMAN_EXECUTION_EXPORT template <typename Sender, typename Receiver> //-dk:TODO detail export
     requires ::beman::execution::detail::
         //-dk:TODO why is the remove_cvref_t needed...?
     valid_specialization<::beman::execution::detail::state_type, std::remove_cvref_t<Sender>, Receiver>
diff --git a/include/beman/execution/detail/basic_state.hpp b/include/beman/execution/detail/basic_state.hpp
index 62d7b781..5542371b 100644
--- a/include/beman/execution/detail/basic_state.hpp
+++ b/include/beman/execution/detail/basic_state.hpp
@@ -20,7 +20,8 @@ namespace beman::execution::detail {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-template <typename Sender, typename Receiver>
+//-dk:TODO the export below shouldn't be needed, but MSVC++ seems to require it (2026-02-01)
+BEMAN_EXECUTION_EXPORT template <typename Sender, typename Receiver> //-dk:TODO detail export
 struct basic_state {
     basic_state(Sender&& sender, Receiver&& rcvr) noexcept(true)
         : receiver(::std::move(rcvr)),
diff --git a/include/beman/execution/detail/connect_all.hpp b/include/beman/execution/detail/connect_all.hpp
index afc36186..80d5b4c8 100644
--- a/include/beman/execution/detail/connect_all.hpp
+++ b/include/beman/execution/detail/connect_all.hpp
@@ -122,7 +122,8 @@ struct connect_all_t {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-inline constexpr connect_all_t connect_all{};
+//-dk:TODO the export below shouldn't be needed, but MSVC++ seems to require it (2026-02-01)
+BEMAN_EXECUTION_EXPORT constexpr connect_all_t connect_all{}; //-dk:TODO detail export
 } // namespace beman::execution::detail
 
 #include <beman/execution/detail/suppress_pop.hpp>
diff --git a/include/beman/execution/detail/default_impls.hpp b/include/beman/execution/detail/default_impls.hpp
index 5576c902..fc705570 100644
--- a/include/beman/execution/detail/default_impls.hpp
+++ b/include/beman/execution/detail/default_impls.hpp
@@ -36,34 +36,43 @@ struct default_impls {
         }
     };
     static constexpr auto get_attrs = get_attrs_impl{};
-    static constexpr auto get_env   = [](auto, auto&, const auto& receiver) noexcept -> decltype(auto) {
-        return ::beman::execution::detail::fwd_env(::beman::execution::get_env(receiver));
+    struct get_env_impl {
+        auto operator()(auto, auto&, const auto& receiver) const noexcept -> decltype(auto) {
+            return ::beman::execution::detail::fwd_env(::beman::execution::get_env(receiver));
+        }
     };
-    static constexpr auto get_state =
-        []<typename Sender, typename Receiver>(Sender&& sender, Receiver& receiver) noexcept -> decltype(auto) {
-        auto&& data{[&sender]() -> decltype(auto) {
-            if constexpr (requires {
-                              sender.size();
-                              sender.template get<1>();
-                          })
-                return sender.template get<1>();
-            else
-                return ::beman::execution::detail::get_sender_data(::std::forward<Sender>(sender)).data;
-        }()};
+    static constexpr auto get_env = get_env_impl{};
+    struct get_state_impl {
+        template <typename Sender, typename Receiver>
+        auto operator()(Sender&& sender, Receiver& receiver) const noexcept -> decltype(auto) {
+            auto&& data{[&sender]() -> decltype(auto) {
+                if constexpr (requires {
+                                  sender.size();
+                                  sender.template get<1>();
+                              })
+                    return sender.template get<1>();
+                else
+                    return ::beman::execution::detail::get_sender_data(::std::forward<Sender>(sender)).data;
+            }()};
 
-        return ::beman::execution::detail::allocator_aware_move(::beman::execution::detail::forward_like<Sender>(data),
-                                                                receiver);
+            return ::beman::execution::detail::allocator_aware_move(
+                ::beman::execution::detail::forward_like<Sender>(data), receiver);
+        }
     };
-    static constexpr auto start = [](auto&, auto&, auto&... ops) noexcept -> void {
-        (::beman::execution::start(ops), ...);
+    static constexpr auto get_state = get_state_impl{};
+    struct start_impl {
+        auto operator()(auto&, auto&, auto&... ops) const noexcept -> void { (::beman::execution::start(ops), ...); }
     };
-    static constexpr auto complete = []<typename Index, typename Receiver, typename Tag, typename... Args>(
-                                         Index, auto&, Receiver& receiver, Tag, Args&&... args) noexcept -> void
-        requires ::beman::execution::detail::callable<Tag, Receiver, Args...>
-    {
-        static_assert(Index::value == 0);
-        Tag()(::std::move(receiver), ::std::forward<Args>(args)...);
+    static constexpr auto start = start_impl{};
+    struct complete_impl {
+        template <typename Index, typename Receiver, typename Tag, typename... Args>
+            requires ::beman::execution::detail::callable<Tag, Receiver, Args...>
+        auto operator()(Index, auto&, Receiver& receiver, Tag, Args&&... args) const noexcept -> void {
+            static_assert(Index::value == 0);
+            Tag()(::std::move(receiver), ::std::forward<Args>(args)...);
+        }
     };
+    static constexpr auto complete = complete_impl{};
 };
 } // namespace beman::execution::detail
 
diff --git a/include/beman/execution/detail/env.hpp b/include/beman/execution/detail/env.hpp
index a5e9c072..9b87229b 100644
--- a/include/beman/execution/detail/env.hpp
+++ b/include/beman/execution/detail/env.hpp
@@ -12,8 +12,10 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <::beman::execution::detail::queryable>
-struct env_base;
+template <::beman::execution::detail::queryable Env>
+struct env_base {
+    Env env_;
+};
 
 template <typename E, typename Q>
 concept has_query = requires(const E& e) { e.query(::std::declval<Q>()); };
@@ -32,23 +34,11 @@ struct find_env<Q, E0, E...> {
 };
 } // namespace beman::execution::detail
 
-namespace beman::execution {
-BEMAN_EXECUTION_EXPORT template <::beman::execution::detail::queryable... Envs>
-struct env;
-
-template <::beman::execution::detail::queryable... Envs>
-env(Envs...) -> env<::std::unwrap_reference_t<Envs>...>;
-} // namespace beman::execution
-
 // ----------------------------------------------------------------------------
 
-template <::beman::execution::detail::queryable Env>
-struct beman::execution::detail::env_base {
-    Env env_;
-};
-
-template <::beman::execution::detail::queryable... Envs>
-struct beman::execution::env : ::beman::execution::detail::env_base<Envs>... {
+namespace beman::execution {
+BEMAN_EXECUTION_EXPORT template <::beman::execution::detail::queryable... Envs>
+struct env : ::beman::execution::detail::env_base<Envs>... {
     [[no_unique_address]] ::beman::execution::detail::non_assignable na_{};
 
     template <typename Q>
@@ -59,6 +49,10 @@ struct beman::execution::env : ::beman::execution::detail::env_base<Envs>... {
     }
 };
 
+template <::beman::execution::detail::queryable... Envs>
+env(Envs...) -> env<::std::unwrap_reference_t<Envs>...>;
+} // namespace beman::execution
+
 // ----------------------------------------------------------------------------
 
 #endif // INCLUDED_BEMAN_EXECUTION_DETAIL_ENV
diff --git a/include/beman/execution/detail/env_promise.hpp b/include/beman/execution/detail/env_promise.hpp
index 979546b6..b8594dad 100644
--- a/include/beman/execution/detail/env_promise.hpp
+++ b/include/beman/execution/detail/env_promise.hpp
@@ -16,7 +16,7 @@ namespace beman::execution::detail {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-template <typename Env>
+BEMAN_EXECUTION_EXPORT template <typename Env> //-dk:TODO detail export
 struct env_promise : ::beman::execution::detail::with_await_transform<Env> {
     auto get_return_object() noexcept -> void;
     auto initial_suspend() noexcept -> ::std::suspend_always;
diff --git a/include/beman/execution/detail/fwd_env.hpp b/include/beman/execution/detail/fwd_env.hpp
index 9c6b27e2..e85eaee4 100644
--- a/include/beman/execution/detail/fwd_env.hpp
+++ b/include/beman/execution/detail/fwd_env.hpp
@@ -19,7 +19,7 @@ namespace beman::execution::detail {
  * \headerfile beman/execution/execution.hpp <beman/execution/execution.hpp>
  * \internal
  */
-template <typename Env>
+BEMAN_EXECUTION_EXPORT template <typename Env> //-dk:TODO detail export
 class fwd_env {
   private:
     Env env;
diff --git a/include/beman/execution/detail/has_completions.hpp b/include/beman/execution/detail/has_completions.hpp
index ec756ff6..24d747ab 100644
--- a/include/beman/execution/detail/has_completions.hpp
+++ b/include/beman/execution/detail/has_completions.hpp
@@ -11,26 +11,11 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-#if not defined(__clang__)
-// The version of clang current (2024-09-01) installed on my Mac crashes
-// with this code - thus, there is a work-around.
 template <typename Receiver, typename Completions>
 concept has_completions = requires(Completions* completions) {
     []<::beman::execution::detail::valid_completion_for<Receiver>... Signatures>(
         ::beman::execution::completion_signatures<Signatures...>*) {}(completions);
 };
-#else
-template <typename, typename>
-struct has_completions_aux;
-template <typename Receiver, typename... Signature>
-struct has_completions_aux<Receiver, ::beman::execution::completion_signatures<Signature...>> {
-    static constexpr bool value =
-        (::beman::execution::detail::valid_completion_for<Signature, Receiver> && ... && true);
-};
-
-template <typename Receiver, typename Completions>
-concept has_completions = has_completions_aux<Receiver, Completions>::value;
-#endif
 } // namespace beman::execution::detail
 
 // ----------------------------------------------------------------------------
diff --git a/include/beman/execution/detail/indices_for.hpp b/include/beman/execution/detail/indices_for.hpp
index c5f9ce29..75358276 100644
--- a/include/beman/execution/detail/indices_for.hpp
+++ b/include/beman/execution/detail/indices_for.hpp
@@ -10,9 +10,10 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <typename Sender>
+//-dk:TODO the export below shouldn't be needed, but MSVC++ seems to require it (2026-02-01)
+BEMAN_EXECUTION_EXPORT template <typename Sender> //-dk:TODO detail export
 using indices_for = typename ::std::remove_reference_t<Sender>::indices_for;
-}
+} // namespace beman::execution::detail
 
 // ----------------------------------------------------------------------------
 
diff --git a/include/beman/execution/detail/join_env.hpp b/include/beman/execution/detail/join_env.hpp
index 01ee4592..a582d08a 100644
--- a/include/beman/execution/detail/join_env.hpp
+++ b/include/beman/execution/detail/join_env.hpp
@@ -21,33 +21,39 @@ class join_env {
     template <typename E1, typename E2>
     join_env(E1&& e1, E2&& e2) : env1(::std::forward<E1>(e1)), env2(::std::forward<E2>(e2)) {}
 
+    template <typename Query, typename... Args>
+        requires requires(Env1&, const Query& query, Args&&... args) {
+            env1.query(query, ::std::forward<Args>(args)...);
+        }
+    auto query(const Query& query, Args&&... args) noexcept -> decltype(auto) {
+        return this->env1.query(query, ::std::forward<Args>(args)...);
+    }
     template <typename Query, typename... Args>
         requires(
-            requires(Env1&, const Query& query, Args&&... args) {
+            not requires(Env1&, const Query& query, Args&&... args) {
                 env1.query(query, ::std::forward<Args>(args)...);
-            } ||
+            } &&
             requires(Env2& e2, const Query& query, Args&&... args) { e2.query(query, ::std::forward<Args>(args)...); })
     auto query(const Query& query, Args&&... args) noexcept -> decltype(auto) {
-        if constexpr (requires { env1.query(query, ::std::forward<Args>(args)...); }) {
-            return env1.query(query, ::std::forward<Args>(args)...);
-        } else {
-            return env2.query(query, ::std::forward<Args>(args)...);
+        return this->env2.query(query, ::std::forward<Args>(args)...);
+    }
+    template <typename Query, typename... Args>
+        requires requires(const Env1& e1, const Query& query, Args&&... args) {
+            { e1.query(query, ::std::forward<Args>(args)...) } noexcept;
         }
+    auto query(const Query& query, Args&&... args) const noexcept -> decltype(auto) {
+        return this->env1.query(query, ::std::forward<Args>(args)...);
     }
     template <typename Query, typename... Args>
         requires(
-            requires(const Env1&, const Query& query, Args&&... args) {
-                env1.query(query, ::std::forward<Args>(args)...);
-            } ||
+            not requires(const Env1& e1, const Query& query, Args&&... args) {
+                { e1.query(query, ::std::forward<Args>(args)...) } noexcept;
+            } &&
             requires(const Env2& e2, const Query& query, Args&&... args) {
-                e2.query(query, ::std::forward<Args>(args)...);
+                { e2.query(query, ::std::forward<Args>(args)...) } noexcept;
             })
     auto query(const Query& query, Args&&... args) const noexcept -> decltype(auto) {
-        if constexpr (requires { env1.query(query, ::std::forward<Args>(args)...); }) {
-            return env1.query(query, ::std::forward<Args>(args)...);
-        } else {
-            return env2.query(query, ::std::forward<Args>(args)...);
-        }
+        return this->env2.query(query, ::std::forward<Args>(args)...);
     }
 };
 
diff --git a/include/beman/execution/detail/make_env.hpp b/include/beman/execution/detail/make_env.hpp
index 1d92d9aa..535e84cc 100644
--- a/include/beman/execution/detail/make_env.hpp
+++ b/include/beman/execution/detail/make_env.hpp
@@ -11,7 +11,7 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <typename Query, typename Value>
+BEMAN_EXECUTION_EXPORT template <typename Query, typename Value> //-dk:TODO detail export
 class make_env {
   private:
     Value value;
diff --git a/include/beman/execution/detail/sender_adaptor.hpp b/include/beman/execution/detail/sender_adaptor.hpp
index 560c6d34..a23d3bdc 100644
--- a/include/beman/execution/detail/sender_adaptor.hpp
+++ b/include/beman/execution/detail/sender_adaptor.hpp
@@ -16,7 +16,7 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <typename Adaptor, typename... T>
+BEMAN_EXECUTION_EXPORT template <typename Adaptor, typename... T> //-dk:TODO detail export
 struct sender_adaptor : ::beman::execution::detail::product_type<::std::decay_t<Adaptor>, ::std::decay_t<T>...>,
                         ::beman::execution::sender_adaptor_closure<sender_adaptor<Adaptor, T...>> {
     template <::beman::execution::sender Sender, typename Self>
diff --git a/include/beman/execution/detail/simple_allocator.hpp b/include/beman/execution/detail/simple_allocator.hpp
index 90bde1c0..eab53f60 100644
--- a/include/beman/execution/detail/simple_allocator.hpp
+++ b/include/beman/execution/detail/simple_allocator.hpp
@@ -11,7 +11,7 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <typename Alloc>
+BEMAN_EXECUTION_EXPORT template <typename Alloc> //-dk:TODO detail export
 concept simple_allocator =
     requires(::std::remove_cvref_t<Alloc> alloc, ::std::size_t n) {
         { *alloc.allocate(n) } -> ::std::same_as<typename ::std::remove_cvref_t<Alloc>::value_type&>;
diff --git a/include/beman/execution/detail/stoppable_source.hpp b/include/beman/execution/detail/stoppable_source.hpp
index 570d80e0..3bad57a7 100644
--- a/include/beman/execution/detail/stoppable_source.hpp
+++ b/include/beman/execution/detail/stoppable_source.hpp
@@ -11,7 +11,7 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-template <typename Source>
+BEMAN_EXECUTION_EXPORT template <typename Source> //-dk:TODO detail export
 concept stoppable_source = requires(Source& source, const Source& csource) {
     { csource.get_token() } -> ::beman::execution::stoppable_token;
     { csource.stop_possible() } noexcept -> ::std::same_as<bool>;
diff --git a/include/beman/execution/detail/sync_wait.hpp b/include/beman/execution/detail/sync_wait.hpp
index 1c4bde65..ffceee6b 100644
--- a/include/beman/execution/detail/sync_wait.hpp
+++ b/include/beman/execution/detail/sync_wait.hpp
@@ -26,21 +26,22 @@
 // ----------------------------------------------------------------------------
 
 namespace beman::execution::detail {
-struct sync_wait_env {
+BEMAN_EXECUTION_EXPORT struct sync_wait_env { // dk:TODO detail export
     ::beman::execution::run_loop* loop{};
 
     auto query(::beman::execution::get_scheduler_t) const noexcept { return this->loop->get_scheduler(); }
     auto query(::beman::execution::get_delegation_scheduler_t) const noexcept { return this->loop->get_scheduler(); }
 };
 
-template <::beman::execution::sender_in<::beman::execution::detail::sync_wait_env> Sender>
+BEMAN_EXECUTION_EXPORT template <
+    ::beman::execution::sender_in<::beman::execution::detail::sync_wait_env> Sender> // dk:TODO detail export
 using sync_wait_result_type =
     ::std::optional<::beman::execution::value_types_of_t<Sender,
                                                          ::beman::execution::detail::sync_wait_env,
                                                          ::beman::execution::detail::decayed_tuple,
                                                          ::std::type_identity_t>>;
 
-template <typename Sender>
+BEMAN_EXECUTION_EXPORT template <typename Sender> // dk:TODO detail export
 struct sync_wait_state {
     ::beman::execution::run_loop loop{};
     ::std::exception_ptr         error{};
@@ -48,7 +49,7 @@ struct sync_wait_state {
     ::beman::execution::detail::sync_wait_result_type<Sender> result{};
 };
 
-template <typename Sender>
+BEMAN_EXECUTION_EXPORT template <typename Sender> // dk:TODO detail export
 struct sync_wait_receiver {
     using receiver_concept = ::beman::execution::receiver_t;
 
diff --git a/include/beman/execution/detail/valid_completion_for.hpp b/include/beman/execution/detail/valid_completion_for.hpp
index 51aae9e1..9b69b057 100644
--- a/include/beman/execution/detail/valid_completion_for.hpp
+++ b/include/beman/execution/detail/valid_completion_for.hpp
@@ -24,7 +24,7 @@ struct valid_completion_for_aux<Rcvr, Tag (*)(Args...)> {
     {}
 };
 
-template <typename Signature, typename Rcvr>
+BEMAN_EXECUTION_EXPORT template <typename Signature, typename Rcvr> // dk:TODO detail export
 concept valid_completion_for = requires(Signature* signature) {
 #if 1
     valid_completion_for_aux<Rcvr, Signature*>::test(signature);
diff --git a/src/beman/execution/execution.cppm b/src/beman/execution/execution.cppm
index 5827331d..1a954b35 100644
--- a/src/beman/execution/execution.cppm
+++ b/src/beman/execution/execution.cppm
@@ -11,43 +11,43 @@ module;
 #ifdef BEMAN_HAS_IMPORT_STD
 import std;
 #else
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <algorithm>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <atomic>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <cassert>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <concepts>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <condition_variable>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <coroutine>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <cstddef>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <cstdlib>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <exception>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <functional>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <memory>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <mutex>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <optional>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <system_error>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <thread>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <tuple>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <type_traits>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <utility>
-#line 240 "./bin/mk-module.py"
+#line 239 "./bin/mk-module.py"
 #include <variant>
 #endif
 
@@ -328,7 +328,7 @@ struct beman::execution::detail::non_assignable {
 
 #line 13 "include/beman/execution/detail/simple_allocator.hpp"
 namespace beman::execution::detail {
-template <typename Alloc>
+export /* --------- */ template <typename Alloc>
 concept simple_allocator =
     requires(::std::remove_cvref_t<Alloc> alloc, ::std::size_t n) {
         { *alloc.allocate(n) } -> ::std::same_as<typename ::std::remove_cvref_t<Alloc>::value_type&>;
@@ -442,33 +442,39 @@ class join_env {
     template <typename E1, typename E2>
     join_env(E1&& e1, E2&& e2) : env1(::std::forward<E1>(e1)), env2(::std::forward<E2>(e2)) {}
 
+    template <typename Query, typename... Args>
+        requires requires(Env1&, const Query& query, Args&&... args) {
+            env1.query(query, ::std::forward<Args>(args)...);
+        }
+    auto query(const Query& query, Args&&... args) noexcept -> decltype(auto) {
+        return this->env1.query(query, ::std::forward<Args>(args)...);
+    }
     template <typename Query, typename... Args>
         requires(
-            requires(Env1&, const Query& query, Args&&... args) {
+            not requires(Env1&, const Query& query, Args&&... args) {
                 env1.query(query, ::std::forward<Args>(args)...);
-            } ||
+            } &&
             requires(Env2& e2, const Query& query, Args&&... args) { e2.query(query, ::std::forward<Args>(args)...); })
     auto query(const Query& query, Args&&... args) noexcept -> decltype(auto) {
-        if constexpr (requires { env1.query(query, ::std::forward<Args>(args)...); }) {
-            return env1.query(query, ::std::forward<Args>(args)...);
-        } else {
-            return env2.query(query, ::std::forward<Args>(args)...);
+        return this->env2.query(query, ::std::forward<Args>(args)...);
+    }
+    template <typename Query, typename... Args>
+        requires requires(const Env1& e1, const Query& query, Args&&... args) {
+            { e1.query(query, ::std::forward<Args>(args)...) } noexcept;
         }
+    auto query(const Query& query, Args&&... args) const noexcept -> decltype(auto) {
+        return this->env1.query(query, ::std::forward<Args>(args)...);
     }
     template <typename Query, typename... Args>
         requires(
-            requires(const Env1&, const Query& query, Args&&... args) {
-                env1.query(query, ::std::forward<Args>(args)...);
-            } ||
+            not requires(const Env1& e1, const Query& query, Args&&... args) {
+                { e1.query(query, ::std::forward<Args>(args)...) } noexcept;
+            } &&
             requires(const Env2& e2, const Query& query, Args&&... args) {
-                e2.query(query, ::std::forward<Args>(args)...);
+                { e2.query(query, ::std::forward<Args>(args)...) } noexcept;
             })
     auto query(const Query& query, Args&&... args) const noexcept -> decltype(auto) {
-        if constexpr (requires { env1.query(query, ::std::forward<Args>(args)...); }) {
-            return env1.query(query, ::std::forward<Args>(args)...);
-        } else {
-            return env2.query(query, ::std::forward<Args>(args)...);
-        }
+        return this->env2.query(query, ::std::forward<Args>(args)...);
     }
 };
 
@@ -641,7 +647,7 @@ using decayed_tuple = ::std::tuple<::std::decay_t<T>...>;
 
 #line 13 "include/beman/execution/detail/make_env.hpp"
 namespace beman::execution::detail {
-template <typename Query, typename Value>
+export /* --------- */ template <typename Query, typename Value>
 class make_env {
   private:
     Value value;
@@ -982,7 +988,8 @@ struct indirect_meta_apply {
 
 #line 12 "include/beman/execution/detail/indices_for.hpp"
 namespace beman::execution::detail {
-template <typename Sender>
+
+export /* --------- */ template <typename Sender>
 using indices_for = typename ::std::remove_reference_t<Sender>::indices_for;
 }
 #line 12 "include/beman/execution/detail/decayed_typeof.hpp"
@@ -1004,8 +1011,10 @@ export /* --------- */ inline constexpr nostopstate_t nostopstate{};
 
 #line 14 "include/beman/execution/detail/env.hpp"
 namespace beman::execution::detail {
-template <::beman::execution::detail::queryable>
-struct env_base;
+template <::beman::execution::detail::queryable Env>
+struct env_base {
+    Env env_;
+};
 
 template <typename E, typename Q>
 concept has_query = requires(const E& e) { e.query(::std::declval<Q>()); };
@@ -1024,22 +1033,10 @@ struct find_env<Q, E0, E...> {
 };
 } // namespace beman::execution::detail
 
+#line 39 "include/beman/execution/detail/env.hpp"
 namespace beman::execution {
 export /* --------- */ template <::beman::execution::detail::queryable... Envs>
-struct env;
-
-template <::beman::execution::detail::queryable... Envs>
-env(Envs...) -> env<::std::unwrap_reference_t<Envs>...>;
-} // namespace beman::execution
-
-#line 45 "include/beman/execution/detail/env.hpp"
-template <::beman::execution::detail::queryable Env>
-struct beman::execution::detail::env_base {
-    Env env_;
-};
-
-template <::beman::execution::detail::queryable... Envs>
-struct beman::execution::env : ::beman::execution::detail::env_base<Envs>... {
+struct env : ::beman::execution::detail::env_base<Envs>... {
     [[no_unique_address]] ::beman::execution::detail::non_assignable na_{};
 
     template <typename Q>
@@ -1050,6 +1047,10 @@ struct beman::execution::env : ::beman::execution::detail::env_base<Envs>... {
     }
 };
 
+template <::beman::execution::detail::queryable... Envs>
+env(Envs...) -> env<::std::unwrap_reference_t<Envs>...>;
+} // namespace beman::execution
+
 #line 17 "include/beman/execution/detail/get_allocator.hpp"
 namespace beman::execution {
 export /* --------- */ struct get_allocator_t {
@@ -1159,7 +1160,7 @@ struct valid_completion_for_aux<Rcvr, Tag (*)(Args...)> {
     {}
 };
 
-template <typename Signature, typename Rcvr>
+export /* --------- */ template <typename Signature, typename Rcvr>
 concept valid_completion_for = requires(Signature* signature) {
 #if 1
     valid_completion_for_aux<Rcvr, Signature*>::test(signature);
@@ -1251,7 +1252,7 @@ concept completion_tag =
 namespace beman::execution::detail {
 
 #line 19 "include/beman/execution/detail/await_result_type.hpp"
-template <typename T, typename Promise>
+export /* --------- */ template <typename T, typename Promise>
 using await_result_type =
     decltype(::beman::execution::detail::get_awaiter(::std::declval<T>(), ::std::declval<Promise&>()).await_resume());
 } // namespace beman::execution::detail
@@ -1260,7 +1261,7 @@ using await_result_type =
 namespace beman::execution::detail {
 
 #line 22 "include/beman/execution/detail/fwd_env.hpp"
-template <typename Env>
+export /* --------- */ template <typename Env>
 class fwd_env {
   private:
     Env env;
@@ -2160,7 +2161,7 @@ using variant_or_empty = typename ::beman::execution::detail::variant_or_empty_h
 
 #line 13 "include/beman/execution/detail/stoppable_source.hpp"
 namespace beman::execution::detail {
-template <typename Source>
+export /* --------- */ template <typename Source>
 concept stoppable_source = requires(Source& source, const Source& csource) {
     { csource.get_token() } -> ::beman::execution::stoppable_token;
     { csource.stop_possible() } noexcept -> ::std::same_as<bool>;
@@ -2247,26 +2248,11 @@ concept has_as_awaitable = requires(T&& obj, Promise& promise) {
 
 #line 13 "include/beman/execution/detail/has_completions.hpp"
 namespace beman::execution::detail {
-#if not defined(__clang__)
-
-#line 17 "include/beman/execution/detail/has_completions.hpp"
 template <typename Receiver, typename Completions>
 concept has_completions = requires(Completions* completions) {
     []<::beman::execution::detail::valid_completion_for<Receiver>... Signatures>(
         ::beman::execution::completion_signatures<Signatures...>*) {}(completions);
 };
-#else
-template <typename, typename>
-struct has_completions_aux;
-template <typename Receiver, typename... Signature>
-struct has_completions_aux<Receiver, ::beman::execution::completion_signatures<Signature...>> {
-    static constexpr bool value =
-        (::beman::execution::detail::valid_completion_for<Signature, Receiver> && ... && true);
-};
-
-template <typename Receiver, typename Completions>
-concept has_completions = has_completions_aux<Receiver, Completions>::value;
-#endif
 } // namespace beman::execution::detail
 
 #line 23 "include/beman/execution/detail/default_impls.hpp"
@@ -2283,34 +2269,43 @@ struct default_impls {
         }
     };
     static constexpr auto get_attrs = get_attrs_impl{};
-    static constexpr auto get_env   = [](auto, auto&, const auto& receiver) noexcept -> decltype(auto) {
-        return ::beman::execution::detail::fwd_env(::beman::execution::get_env(receiver));
+    struct get_env_impl {
+        auto operator()(auto, auto&, const auto& receiver) const noexcept -> decltype(auto) {
+            return ::beman::execution::detail::fwd_env(::beman::execution::get_env(receiver));
+        }
     };
-    static constexpr auto get_state =
-        []<typename Sender, typename Receiver>(Sender&& sender, Receiver& receiver) noexcept -> decltype(auto) {
-        auto&& data{[&sender]() -> decltype(auto) {
-            if constexpr (requires {
-                              sender.size();
-                              sender.template get<1>();
-                          })
-                return sender.template get<1>();
-            else
-                return ::beman::execution::detail::get_sender_data(::std::forward<Sender>(sender)).data;
-        }()};
+    static constexpr auto get_env = get_env_impl{};
+    struct get_state_impl {
+        template <typename Sender, typename Receiver>
+        auto operator()(Sender&& sender, Receiver& receiver) const noexcept -> decltype(auto) {
+            auto&& data{[&sender]() -> decltype(auto) {
+                if constexpr (requires {
+                                  sender.size();
+                                  sender.template get<1>();
+                              })
+                    return sender.template get<1>();
+                else
+                    return ::beman::execution::detail::get_sender_data(::std::forward<Sender>(sender)).data;
+            }()};
 
-        return ::beman::execution::detail::allocator_aware_move(::beman::execution::detail::forward_like<Sender>(data),
-                                                                receiver);
+            return ::beman::execution::detail::allocator_aware_move(
+                ::beman::execution::detail::forward_like<Sender>(data), receiver);
+        }
     };
-    static constexpr auto start = [](auto&, auto&, auto&... ops) noexcept -> void {
-        (::beman::execution::start(ops), ...);
+    static constexpr auto get_state = get_state_impl{};
+    struct start_impl {
+        auto operator()(auto&, auto&, auto&... ops) const noexcept -> void { (::beman::execution::start(ops), ...); }
     };
-    static constexpr auto complete = []<typename Index, typename Receiver, typename Tag, typename... Args>(
-                                         Index, auto&, Receiver& receiver, Tag, Args&&... args) noexcept -> void
-        requires ::beman::execution::detail::callable<Tag, Receiver, Args...>
-    {
-        static_assert(Index::value == 0);
-        Tag()(::std::move(receiver), ::std::forward<Args>(args)...);
+    static constexpr auto start = start_impl{};
+    struct complete_impl {
+        template <typename Index, typename Receiver, typename Tag, typename... Args>
+            requires ::beman::execution::detail::callable<Tag, Receiver, Args...>
+        auto operator()(Index, auto&, Receiver& receiver, Tag, Args&&... args) const noexcept -> void {
+            static_assert(Index::value == 0);
+            Tag()(::std::move(receiver), ::std::forward<Args>(args)...);
+        }
     };
+    static constexpr auto complete = complete_impl{};
 };
 } // namespace beman::execution::detail
 
@@ -2411,7 +2406,7 @@ using gather_signatures = typename ::beman::execution::detail::gather_signatures
 namespace beman::execution::detail {
 
 #line 19 "include/beman/execution/detail/env_promise.hpp"
-template <typename Env>
+export /* --------- */ template <typename Env>
 struct env_promise : ::beman::execution::detail::with_await_transform<Env> {
     auto get_return_object() noexcept -> void;
     auto initial_suspend() noexcept -> ::std::suspend_always;
@@ -2727,8 +2722,8 @@ auto spawn_get_allocator(const Sndr& sndr, const Ev& ev) {
 #line 17 "include/beman/execution/detail/basic_state.hpp"
 namespace beman::execution::detail {
 
-#line 23 "include/beman/execution/detail/basic_state.hpp"
-template <typename Sender, typename Receiver>
+#line 24 "include/beman/execution/detail/basic_state.hpp"
+export /* --------- */ template <typename Sender, typename Receiver>
 struct basic_state {
     basic_state(Sender&& sender, Receiver&& rcvr) noexcept(true)
         : receiver(::std::move(rcvr)),
@@ -2885,7 +2880,7 @@ constexpr auto transform_sender(Domain dom, Sender&& sender, const Env&... env)
 
 #line 18 "include/beman/execution/detail/sender_adaptor.hpp"
 namespace beman::execution::detail {
-template <typename Adaptor, typename... T>
+export /* --------- */ template <typename Adaptor, typename... T>
 struct sender_adaptor : ::beman::execution::detail::product_type<::std::decay_t<Adaptor>, ::std::decay_t<T>...>,
                         ::beman::execution::sender_adaptor_closure<sender_adaptor<Adaptor, T...>> {
     template <::beman::execution::sender Sender, typename Self>
@@ -2946,7 +2941,7 @@ constexpr auto apply_sender(Domain domain, Tag, Sender&& sender, Args&&... args)
     return domain.apply_sender(Tag(), ::std::forward<Sender>(sender), ::std::forward<Args>(args)...);
 }
 #line 32 "include/beman/execution/detail/apply_sender.hpp"
-template <typename Domain, typename Tag, ::beman::execution::sender Sender, typename... Args>
+export /* --------- */ template <typename Domain, typename Tag, ::beman::execution::sender Sender, typename... Args>
     requires(not requires(Domain domain, Tag tag, Sender&& sender, Args&&... args) {
                 domain.apply_sender(Tag(), ::std::forward<Sender>(sender), ::std::forward<Args>(args)...);
             }) && requires(Tag tag, Sender&& sender, Args&&... args) {
@@ -3778,8 +3773,8 @@ struct connect_all_t {
     }
 };
 
-#line 125 "include/beman/execution/detail/connect_all.hpp"
-inline constexpr connect_all_t connect_all{};
+#line 126 "include/beman/execution/detail/connect_all.hpp"
+export /* --------- */ constexpr connect_all_t connect_all{};
 } // namespace beman::execution::detail
 
 #line 18 "include/beman/execution/detail/error_types_of_t.hpp"
@@ -3835,21 +3830,21 @@ using connect_all_result =
 
 #line 28 "include/beman/execution/detail/sync_wait.hpp"
 namespace beman::execution::detail {
-struct sync_wait_env {
+export /* --------- */ struct sync_wait_env {
     ::beman::execution::run_loop* loop{};
 
     auto query(::beman::execution::get_scheduler_t) const noexcept { return this->loop->get_scheduler(); }
     auto query(::beman::execution::get_delegation_scheduler_t) const noexcept { return this->loop->get_scheduler(); }
 };
 
-template <::beman::execution::sender_in<::beman::execution::detail::sync_wait_env> Sender>
+export /* --------- */ template <::beman::execution::sender_in<::beman::execution::detail::sync_wait_env> Sender>
 using sync_wait_result_type =
     ::std::optional<::beman::execution::value_types_of_t<Sender,
                                                          ::beman::execution::detail::sync_wait_env,
                                                          ::beman::execution::detail::decayed_tuple,
                                                          ::std::type_identity_t>>;
 
-template <typename Sender>
+export /* --------- */ template <typename Sender>
 struct sync_wait_state {
     ::beman::execution::run_loop loop{};
     ::std::exception_ptr         error{};
@@ -3857,7 +3852,7 @@ struct sync_wait_state {
     ::beman::execution::detail::sync_wait_result_type<Sender> result{};
 };
 
-template <typename Sender>
+export /* --------- */ template <typename Sender>
 struct sync_wait_receiver {
     using receiver_concept = ::beman::execution::receiver_t;
 
@@ -3926,8 +3921,8 @@ export /* --------- */ inline constexpr ::beman::execution::sync_wait_t sync_wai
 #line 22 "include/beman/execution/detail/basic_operation.hpp"
 namespace beman::execution::detail {
 
-#line 28 "include/beman/execution/detail/basic_operation.hpp"
-template <typename Sender, typename Receiver>
+#line 29 "include/beman/execution/detail/basic_operation.hpp"
+export /* --------- */ template <typename Sender, typename Receiver>
     requires ::beman::execution::detail::
 
         valid_specialization<::beman::execution::detail::state_type, std::remove_cvref_t<Sender>, Receiver>
@@ -5544,7 +5539,7 @@ export /* --------- */ inline constexpr write_env_t write_env{};
 
 #line 23 "include/beman/execution/detail/associate.hpp"
 namespace beman::execution::detail {
-template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
+export /* --------- */ template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
 struct associate_data {
     using wrap_sender = ::std::remove_cvref_t<decltype(::std::declval<Token&>().wrap(::std::declval<Sender>()))>;
 
@@ -5576,18 +5571,18 @@ struct associate_data {
             this->token.disassociate();
         }
     }
-#line 57 "include/beman/execution/detail/associate.hpp"
+#line 58 "include/beman/execution/detail/associate.hpp"
     auto release() -> ::std::optional<::std::pair<Token, wrap_sender>> {
         return this->sender ? (std::unique_ptr<std::optional<wrap_sender>, decltype([](auto* opt) { opt->reset(); })>(
                                    &this->sender),
                                ::std::optional{::std::pair{::std::move(this->token), ::std::move(*this->sender)}})
                             : ::std::optional<::std::pair<Token, wrap_sender>>{};
     }
-#line 64 "include/beman/execution/detail/associate.hpp"
+#line 65 "include/beman/execution/detail/associate.hpp"
     Token                        token;
     ::std::optional<wrap_sender> sender;
 };
-template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
+export /* --------- */ template <::beman::execution::scope_token Token, ::beman::execution::sender Sender>
 associate_data(Token, Sender&&) -> associate_data<Token, Sender>;
 
 struct associate_t {
@@ -5768,11 +5763,24 @@ struct impls_for<::beman::execution::detail::counting_scope_join_t> : ::beman::e
 
 #line 36 "include/beman/execution/detail/affine_on.hpp"
 namespace beman::execution::detail {
+template <typename Ev>
+struct affine_on_env {
+    Ev   ev_;
+    auto query(const ::beman::execution::get_stop_token_t&) const noexcept -> ::beman::execution::never_stop_token {
+        return ::beman::execution::never_stop_token();
+    }
+    template <typename Q>
+    auto query(const Q& q) const noexcept -> decltype(q(this->ev_)) {
+        return q(this->ev_);
+    }
+};
+template <typename Ev>
+affine_on_env(const Ev&) -> affine_on_env<Ev>;
 
-#line 46 "include/beman/execution/detail/affine_on.hpp"
+#line 59 "include/beman/execution/detail/affine_on.hpp"
 struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
 
-#line 54 "include/beman/execution/detail/affine_on.hpp"
+#line 67 "include/beman/execution/detail/affine_on.hpp"
     template <::beman::execution::sender Sender>
     auto operator()(Sender&& sender) const {
         return ::beman::execution::detail::transform_sender(
@@ -5780,25 +5788,10 @@ struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
             ::beman::execution::detail::make_sender(
                 *this, ::beman::execution::env<>{}, ::std::forward<Sender>(sender)));
     }
-#line 67 "include/beman/execution/detail/affine_on.hpp"
+#line 80 "include/beman/execution/detail/affine_on.hpp"
     auto operator()() const { return ::beman::execution::detail::sender_adaptor{*this}; }
 
-    template <typename Ev>
-    struct ao_env {
-        Ev   ev_;
-        auto query(const ::beman::execution::get_stop_token_t&) const noexcept
-            -> ::beman::execution::never_stop_token {
-            return ::beman::execution::never_stop_token();
-        }
-        template <typename Q>
-        auto query(const Q& q) const noexcept -> decltype(q(this->ev_)) {
-            return q(this->ev_);
-        }
-    };
-    template <typename Ev>
-    ao_env(const Ev&) -> ao_env<Ev>;
-
-#line 102 "include/beman/execution/detail/affine_on.hpp"
+#line 100 "include/beman/execution/detail/affine_on.hpp"
     template <::beman::execution::sender Sender, typename Env>
         requires ::beman::execution::detail::sender_for<Sender, affine_on_t> && requires(const Env& env) {
             { ::beman::execution::get_scheduler(env) } -> ::beman::execution::scheduler;
@@ -5824,7 +5817,7 @@ struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
                 ::beman::execution::schedule_from(
                     ::beman::execution::get_scheduler(ev),
                     ::beman::execution::write_env(::beman::execution::detail::forward_like<Sender>(child), ev)),
-                ao_env(ev));
+                beman::execution::detail::affine_on_env(ev));
         }
     }
 };
@@ -5833,7 +5826,7 @@ struct affine_on_t : ::beman::execution::sender_adaptor_closure<affine_on_t> {
 
 namespace beman::execution {
 
-#line 139 "include/beman/execution/detail/affine_on.hpp"
+#line 137 "include/beman/execution/detail/affine_on.hpp"
 export /* --------- */ using affine_on_t = beman::execution::detail::affine_on_t;
 export /* --------- */ inline constexpr affine_on_t affine_on{};
 } // namespace beman::execution
diff --git a/tests/beman/execution/CMakeLists.txt b/tests/beman/execution/CMakeLists.txt
index ec73465a..7e5cd496 100644
--- a/tests/beman/execution/CMakeLists.txt
+++ b/tests/beman/execution/CMakeLists.txt
@@ -1,34 +1,22 @@
 # src/beman/execution/tests/CMakeLists.txt
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-list(APPEND todo exec-associate.test)
-
 if(BEMAN_USE_MODULES)
     list(APPEND execution_tests execution-module.test stop-token-module.test)
 endif()
 
+set(execution_tests_todo exec-associate.test) #-dk:TODO
+
 list(
     APPEND execution_tests
+    allocator-requirements-general.test
     exec-affine-on.test
-    issue-174.test
-    issue-186.test
-    exec-scope-counting.test
-    exec-spawn.test
-    exec-stop-when.test
-    non_assignable.test
-    exec-prop.test
-    exec-env.test
-    exec-scope-simple-counting.test
-    exec-spawn-future.test
-    exec-scope-concepts.test
-    issue-144.test
-    exec-on.test
-    notify.test
     exec-awaitable.test
-    allocator-requirements-general.test
+    exec-bulk.test
     exec-connect.test
     exec-continues-on.test
     exec-domain-default.test
+    exec-env.test
     exec-fwd-env.test
     exec-general.test
     exec-get-allocator.test
@@ -42,8 +30,10 @@ list(
     exec-into-variant.test
     exec-just.test
     exec-let.test
+    exec-on.test
     exec-opstate-start.test
     exec-opstate.test
+    exec-prop.test
     exec-read-env.test
     exec-recv-concepts.test
     exec-recv.test
@@ -52,6 +42,9 @@ list(
     exec-sched.test
     exec-schedule-from.test
     exec-schedule.test
+    exec-scope-concepts.test
+    exec-scope-counting.test
+    exec-scope-simple-counting.test
     exec-set-error.test
     exec-set-stopped.test
     exec-set-value.test
@@ -59,25 +52,32 @@ list(
     exec-snd-concepts.test
     exec-snd-expos.test
     exec-snd-transform.test
-    exec-starts-on.test
+    exec-spawn-future.test
+    exec-spawn.test
     exec-split.test
+    exec-starts-on.test
+    exec-stop-when.test
     exec-sync-wait.test
     exec-then.test
     exec-utils-cmplsigs.test
     exec-when-all.test
     exec-with-awaitable-senders.test
     execution-queryable-concept.test
-    exec-bulk.test
     execution-syn.test
     forward-like.test
     function-objects.test
     functional-syn.test
+    issue-144.test
+    issue-174.test
+    issue-186.test
     meta-combine.test
     meta-contains.test
     meta-filter.test
     meta-prepend.test
     meta-transform.test
     meta-unique.test
+    non_assignable.test
+    notify.test
     stopcallback-cons.test
     stopcallback-general.test
     stopcallback-inplace-cons.test
@@ -107,6 +107,7 @@ list(
     thread.test
     utilities.test
 )
+# set(execution_tests <test>.test)
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
 
@@ -114,6 +115,7 @@ foreach(test ${execution_tests})
     set(TEST_EXE ${PROJECT_NAME}.${test})
     add_executable(${TEST_EXE} ${test}.cpp)
     if(BEMAN_USE_MODULES)
+        target_compile_definitions(${TEST_EXE} PUBLIC BEMAN_HAS_MODULES)
         target_link_libraries(${TEST_EXE} PRIVATE beman::execution)
     else()
         target_link_libraries(${TEST_EXE} PRIVATE beman::execution_headers)
diff --git a/tests/beman/execution/exec-affine-on.test.cpp b/tests/beman/execution/exec-affine-on.test.cpp
index 0d790799..a5f9f338 100644
--- a/tests/beman/execution/exec-affine-on.test.cpp
+++ b/tests/beman/execution/exec-affine-on.test.cpp
@@ -1,6 +1,10 @@
 // tests/beman/execution/exec-affine-on.test.cpp                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -23,12 +27,6 @@ import beman.execution;
 #include <beman/execution/detail/write_env.hpp>
 #endif
 
-#include <mutex>
-#include <condition_variable>
-#include <thread>
-
-#include <test/execution.hpp>
-
 // ----------------------------------------------------------------------------
 
 namespace {
diff --git a/tests/beman/execution/exec-associate.test.cpp b/tests/beman/execution/exec-associate.test.cpp
index 798a691e..a761027b 100644
--- a/tests/beman/execution/exec-associate.test.cpp
+++ b/tests/beman/execution/exec-associate.test.cpp
@@ -1,6 +1,10 @@
 // tests/beman/execution/exec-associate.test.cpp                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -12,10 +16,6 @@ import beman.execution;
 #include <beman/execution/detail/receiver.hpp>
 #include <beman/execution/detail/sync_wait.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <type_traits>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
@@ -139,7 +139,7 @@ static_assert(test_std::receiver<receiver>);
 
 template <test_std::sender Sender, test_std::scope_token Token>
 auto test_associate(Sender&& sender, Token&& token) -> void {
-    [[maybe_unused]] auto sndr = test_std::associate(std::forward<Sender>(sender), std::forward<Token>(token));
+    auto sndr = test_std::associate(std::forward<Sender>(sender), std::forward<Token>(token));
     static_assert(test_std::sender<decltype(sndr)>);
     test_std::sync_wait(std::move(sndr));
 }
diff --git a/tests/beman/execution/exec-awaitable.test.cpp b/tests/beman/execution/exec-awaitable.test.cpp
index ddc68b29..184e0f3c 100644
--- a/tests/beman/execution/exec-awaitable.test.cpp
+++ b/tests/beman/execution/exec-awaitable.test.cpp
@@ -1,21 +1,22 @@
 // src/beman/execution/tests/exec-awaitable.test.cpp                -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+// #include <beman/execution/detail/await_suspend_result.hpp>
+#include <beman/execution/detail/is_awaiter.hpp>
+#include <beman/execution/detail/get_awaiter.hpp>
+#include <beman/execution/detail/with_await_transform.hpp>
+#include <coroutine>
+#include <concepts>
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
-#include <beman/execution/detail/await_suspend_result.hpp>
-#include <beman/execution/detail/is_awaiter.hpp>
 #include <beman/execution/detail/is_awaitable.hpp>
-#include <beman/execution/detail/get_awaiter.hpp>
 #include <beman/execution/detail/await_result_type.hpp>
 #include <beman/execution/detail/has_as_awaitable.hpp>
-#include <beman/execution/detail/with_await_transform.hpp>
 #include <beman/execution/detail/env_promise.hpp>
 #include <test/execution.hpp>
 #endif
-#include <coroutine>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-bulk.test.cpp b/tests/beman/execution/exec-bulk.test.cpp
index c9213011..0678f288 100644
--- a/tests/beman/execution/exec-bulk.test.cpp
+++ b/tests/beman/execution/exec-bulk.test.cpp
@@ -1,18 +1,18 @@
 // src/beman/execution/tests/exec-bulk.test.cpp -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <cstdlib>
+#include <vector>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
+#include "beman/execution/detail/bulk.hpp"
+#include "beman/execution/detail/just.hpp"
 #include "beman/execution/detail/get_completion_signatures.hpp"
 #include "beman/execution/detail/get_env.hpp"
 #include "beman/execution/detail/sync_wait.hpp"
 #endif
-#include <cstdlib>
-#include <test/execution.hpp>
-#include <beman/execution/detail/bulk.hpp>
-#include <beman/execution/detail/just.hpp>
-#include <vector>
 
 namespace {
 auto test_bulk() {
diff --git a/tests/beman/execution/exec-env.test.cpp b/tests/beman/execution/exec-env.test.cpp
index 2cf8569f..40c9b9d8 100644
--- a/tests/beman/execution/exec-env.test.cpp
+++ b/tests/beman/execution/exec-env.test.cpp
@@ -1,6 +1,9 @@
 // tests/beman/execution/exec-env.test.cpp                            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <memory>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -10,8 +13,6 @@ import beman.execution;
 #include <beman/execution/detail/inplace_stop_source.hpp>
 #include <beman/execution/detail/prop.hpp>
 #endif
-#include <type_traits>
-#include <test/execution.hpp>
 
 namespace {}
 
diff --git a/tests/beman/execution/exec-fwd-env.test.cpp b/tests/beman/execution/exec-fwd-env.test.cpp
index a64bb658..72a0860b 100644
--- a/tests/beman/execution/exec-fwd-env.test.cpp
+++ b/tests/beman/execution/exec-fwd-env.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/exec-fwd-env.test.cpp                  -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-general.test.cpp b/tests/beman/execution/exec-general.test.cpp
index d2a0167f..05d5bb5c 100644
--- a/tests/beman/execution/exec-general.test.cpp
+++ b/tests/beman/execution/exec-general.test.cpp
@@ -1,18 +1,18 @@
 // src/beman/execution/tests/exec-general.test.cpp                  -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifdef BEMAN_HAS_MODULES
-import beman.execution;
-#else
-#include <beman/execution/execution.hpp>
-#endif
+#include <test/execution.hpp>
 #include <beman/execution/detail/movable_value.hpp>
 #include <beman/execution/detail/matching_sig.hpp>
 #include <beman/execution/detail/as_except_ptr.hpp>
-#include <test/execution.hpp>
 #include <concepts>
 #include <exception>
 #include <system_error>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-allocator.test.cpp b/tests/beman/execution/exec-get-allocator.test.cpp
index 60ec4657..89608040 100644
--- a/tests/beman/execution/exec-get-allocator.test.cpp
+++ b/tests/beman/execution/exec-get-allocator.test.cpp
@@ -1,9 +1,13 @@
 // src/beman/execution/tests/exec-get-allocator.test.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/execution.hpp>
 #include <test/execution.hpp>
 #include <concepts>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/execution.hpp>
+#endif
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-compl-sched.test.cpp b/tests/beman/execution/exec-get-compl-sched.test.cpp
index 9829335e..2ffb7c11 100644
--- a/tests/beman/execution/exec-get-compl-sched.test.cpp
+++ b/tests/beman/execution/exec-get-compl-sched.test.cpp
@@ -1,6 +1,8 @@
 // src/beman/execution/tests/exec-get-compl-sched.test.cpp          -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <concepts>
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -13,8 +15,6 @@ import beman.execution;
 #include <beman/execution/detail/set_stopped.hpp>
 #include <beman/execution/detail/set_value.hpp>
 #endif
-#include <concepts>
-#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-delegation-scheduler.test.cpp b/tests/beman/execution/exec-get-delegation-scheduler.test.cpp
index e0dc7909..22fffb5f 100644
--- a/tests/beman/execution/exec-get-delegation-scheduler.test.cpp
+++ b/tests/beman/execution/exec-get-delegation-scheduler.test.cpp
@@ -1,6 +1,8 @@
 // src/beman/execution/tests/exec-get-delegation-scheduler.test.cpp -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -10,8 +12,6 @@ import beman.execution;
 #include <beman/execution/detail/scheduler.hpp>
 #include <beman/execution/detail/sender.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-domain.test.cpp b/tests/beman/execution/exec-get-domain.test.cpp
index cb49e744..89c10c3d 100644
--- a/tests/beman/execution/exec-get-domain.test.cpp
+++ b/tests/beman/execution/exec-get-domain.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/exec-get-domain.test.cpp               -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-env.test.cpp b/tests/beman/execution/exec-get-env.test.cpp
index 436f154d..feb1b61a 100644
--- a/tests/beman/execution/exec-get-env.test.cpp
+++ b/tests/beman/execution/exec-get-env.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-get-env.test.cpp                  -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include "test/execution.hpp"
-#include <concepts>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-scheduler.test.cpp b/tests/beman/execution/exec-get-scheduler.test.cpp
index f940ff53..b4c54c8d 100644
--- a/tests/beman/execution/exec-get-scheduler.test.cpp
+++ b/tests/beman/execution/exec-get-scheduler.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-get-scheduler.test.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/get_scheduler.hpp>
 #include <beman/execution/detail/forwarding_query.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-get-stop-token.test.cpp b/tests/beman/execution/exec-get-stop-token.test.cpp
index 03fa880c..52c8d0e9 100644
--- a/tests/beman/execution/exec-get-stop-token.test.cpp
+++ b/tests/beman/execution/exec-get-stop-token.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-get-stop-token.test.cpp           -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #include <beman/execution/stop_token.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-getcomplsigs.test.cpp b/tests/beman/execution/exec-getcomplsigs.test.cpp
index 459f8870..5cfd2515 100644
--- a/tests/beman/execution/exec-getcomplsigs.test.cpp
+++ b/tests/beman/execution/exec-getcomplsigs.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/exec-getcomplsigs.test.cpp             -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-into-variant.test.cpp b/tests/beman/execution/exec-into-variant.test.cpp
index 096ef92c..915eb643 100644
--- a/tests/beman/execution/exec-into-variant.test.cpp
+++ b/tests/beman/execution/exec-into-variant.test.cpp
@@ -1,6 +1,11 @@
 // src/beman/execution/tests/exec-into-variant.test.cpp             -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <exception>
+#include <type_traits>
+#include <variant>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -11,11 +16,6 @@ import beman.execution;
 #include <beman/execution/detail/operation_state.hpp>
 #include <beman/execution/detail/sender.hpp>
 #endif
-#include <test/execution.hpp>
-
-#include <concepts>
-#include <exception>
-#include <type_traits>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-let.test.cpp b/tests/beman/execution/exec-let.test.cpp
index 650d4d47..a0be5e79 100644
--- a/tests/beman/execution/exec-let.test.cpp
+++ b/tests/beman/execution/exec-let.test.cpp
@@ -1,6 +1,13 @@
 // src/beman/execution/tests/exec-let.test.cpp                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <array>
+#include <cstdlib>
+#include <concepts>
+#include <memory_resource>
+#include <span>
+#include <vector>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -11,13 +18,6 @@ import beman.execution;
 #include <beman/execution/detail/read_env.hpp>
 #include <beman/execution/detail/sync_wait.hpp>
 #endif
-#include <test/execution.hpp>
-#include <array>
-#include <cstdlib>
-#include <concepts>
-#include <memory_resource>
-#include <span>
-#include <vector>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-opstate-start.test.cpp b/tests/beman/execution/exec-opstate-start.test.cpp
index 5a087a9d..681a0e4e 100644
--- a/tests/beman/execution/exec-opstate-start.test.cpp
+++ b/tests/beman/execution/exec-opstate-start.test.cpp
@@ -1,14 +1,13 @@
 // src/beman/execution/tests/exec-opstate-start.test.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-opstate.test.cpp b/tests/beman/execution/exec-opstate.test.cpp
index fa0c7ff9..4d7a4811 100644
--- a/tests/beman/execution/exec-opstate.test.cpp
+++ b/tests/beman/execution/exec-opstate.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/exec-opstate.test.cpp                  -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/operation_state.hpp>
 #endif
-#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-prop.test.cpp b/tests/beman/execution/exec-prop.test.cpp
index 9d4c198c..e3920cf3 100644
--- a/tests/beman/execution/exec-prop.test.cpp
+++ b/tests/beman/execution/exec-prop.test.cpp
@@ -1,15 +1,15 @@
 // tests/beman/execution/exec-prop.test.cpp                           -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/prop.hpp>
 #include <beman/execution/detail/forwarding_query.hpp>
 #endif
-#include <type_traits>
-#include <concepts>
-#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-read-env.test.cpp b/tests/beman/execution/exec-read-env.test.cpp
index 2e6b7ed9..5748a67a 100644
--- a/tests/beman/execution/exec-read-env.test.cpp
+++ b/tests/beman/execution/exec-read-env.test.cpp
@@ -1,6 +1,8 @@
 // src/beman/execution/tests/exec-read-env.test.cpp                 -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -14,8 +16,6 @@ import beman.execution;
 #include <beman/execution/detail/start.hpp>
 #include <beman/execution/detail/get_stop_token.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-recv.test.cpp b/tests/beman/execution/exec-recv.test.cpp
index 3b89d993..69785e1b 100644
--- a/tests/beman/execution/exec-recv.test.cpp
+++ b/tests/beman/execution/exec-recv.test.cpp
@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <beman/execution/execution.hpp>
-#include "test/execution.hpp"
+#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-run-loop-general.test.cpp b/tests/beman/execution/exec-run-loop-general.test.cpp
index 0b21ced8..d322e1c0 100644
--- a/tests/beman/execution/exec-run-loop-general.test.cpp
+++ b/tests/beman/execution/exec-run-loop-general.test.cpp
@@ -1,15 +1,15 @@
 // src/beman/execution/tests/exec-run-loop-general.test.cpp         -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/run_loop.hpp>
 #include <beman/execution/detail/scheduler.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <type_traits>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-run-loop-types.test.cpp b/tests/beman/execution/exec-run-loop-types.test.cpp
index 67f5252a..2f0be8e6 100644
--- a/tests/beman/execution/exec-run-loop-types.test.cpp
+++ b/tests/beman/execution/exec-run-loop-types.test.cpp
@@ -1,6 +1,9 @@
 // src/beman/execution/tests/exec-run-loop-types.test.cpp           -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <exception>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -16,9 +19,6 @@ import beman.execution;
 #include <beman/execution/detail/scheduler.hpp>
 #include <beman/execution/detail/sender.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <exception>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-sched.test.cpp b/tests/beman/execution/exec-sched.test.cpp
index ee1e1164..363791a9 100644
--- a/tests/beman/execution/exec-sched.test.cpp
+++ b/tests/beman/execution/exec-sched.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/exec-sched.test.cpp                    -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/scheduler.hpp>
 #endif
-#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-schedule-from.test.cpp b/tests/beman/execution/exec-schedule-from.test.cpp
index ae75b983..d16e338d 100644
--- a/tests/beman/execution/exec-schedule-from.test.cpp
+++ b/tests/beman/execution/exec-schedule-from.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-schedule-from.test.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/schedule_from.hpp>
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-schedule.test.cpp b/tests/beman/execution/exec-schedule.test.cpp
index 82c1568e..b786e074 100644
--- a/tests/beman/execution/exec-schedule.test.cpp
+++ b/tests/beman/execution/exec-schedule.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-schedule.test.cpp                 -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/schedule.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-scope-concepts.test.cpp b/tests/beman/execution/exec-scope-concepts.test.cpp
index b216f647..0947b738 100644
--- a/tests/beman/execution/exec-scope-concepts.test.cpp
+++ b/tests/beman/execution/exec-scope-concepts.test.cpp
@@ -1,6 +1,9 @@
 // tests/beman/execution/exec-scope-concepts.test.cpp                 -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -10,9 +13,6 @@ import beman.execution;
 #include <beman/execution/detail/completion_signatures.hpp>
 #include <beman/execution/detail/set_value.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-scope-counting.test.cpp b/tests/beman/execution/exec-scope-counting.test.cpp
index 85eeca8d..c5438a98 100644
--- a/tests/beman/execution/exec-scope-counting.test.cpp
+++ b/tests/beman/execution/exec-scope-counting.test.cpp
@@ -1,6 +1,10 @@
 // tests/beman/execution/exec-scope-counting.test.cpp                 -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <tuple>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -9,10 +13,7 @@ import beman.execution;
 #include <beman/execution/detail/just.hpp>
 #include <beman/execution/detail/sync_wait.hpp>
 #endif
-#include <test/execution.hpp>
 #include <test/inline_scheduler.hpp>
-#include <concepts>
-#include <type_traits>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-scope-simple-counting.test.cpp b/tests/beman/execution/exec-scope-simple-counting.test.cpp
index c9733448..f55b0fd4 100644
--- a/tests/beman/execution/exec-scope-simple-counting.test.cpp
+++ b/tests/beman/execution/exec-scope-simple-counting.test.cpp
@@ -1,6 +1,10 @@
 // tests/beman/execution/exec-scope-simple-counting.test.cpp          -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <tuple>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -9,10 +13,7 @@ import beman.execution;
 #include <beman/execution/detail/just.hpp>
 #include <beman/execution/detail/sync_wait.hpp>
 #endif
-#include <test/execution.hpp>
 #include <test/inline_scheduler.hpp>
-#include <concepts>
-#include <type_traits>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-set-error.test.cpp b/tests/beman/execution/exec-set-error.test.cpp
index 446a3e4c..8d446fcb 100644
--- a/tests/beman/execution/exec-set-error.test.cpp
+++ b/tests/beman/execution/exec-set-error.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-set-error.test.cpp                      -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include "test/execution.hpp"
-#include <concepts>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-set-stopped.test.cpp b/tests/beman/execution/exec-set-stopped.test.cpp
index f9bbf787..01e6929c 100644
--- a/tests/beman/execution/exec-set-stopped.test.cpp
+++ b/tests/beman/execution/exec-set-stopped.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-set-stopped.test.cpp              -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include "test/execution.hpp"
-#include <concepts>
-#include <utility>
 
 namespace {
 struct receiver {
diff --git a/tests/beman/execution/exec-set-value.test.cpp b/tests/beman/execution/exec-set-value.test.cpp
index bb79061e..d47dfa06 100644
--- a/tests/beman/execution/exec-set-value.test.cpp
+++ b/tests/beman/execution/exec-set-value.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/exec-set-value.test.cpp                -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-snd-apply.test.cpp b/tests/beman/execution/exec-snd-apply.test.cpp
index bd77e331..a4239dfd 100644
--- a/tests/beman/execution/exec-snd-apply.test.cpp
+++ b/tests/beman/execution/exec-snd-apply.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/exec-snd-apply.test.cpp                -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/apply_sender.hpp>
 #endif
-#include <test/execution.hpp>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-snd-expos.test.cpp b/tests/beman/execution/exec-snd-expos.test.cpp
index 1f3bdedf..ee604b79 100644
--- a/tests/beman/execution/exec-snd-expos.test.cpp
+++ b/tests/beman/execution/exec-snd-expos.test.cpp
@@ -70,14 +70,14 @@ struct env {
 
 struct env1 {
     int  value{};
-    auto query(custom_query_t<0>, int a) const { return this->value + a; }
-    auto query(custom_query_t<1>, int a) const { return this->value + a; }
+    auto query(custom_query_t<0>, int a) const noexcept { return this->value + a; }
+    auto query(custom_query_t<1>, int a) const noexcept { return this->value + a; }
 };
 
 struct env2 {
     int  value{};
-    auto query(custom_query_t<0>, int a) const { return this->value + a; }
-    auto query(custom_query_t<2>, int a) const { return this->value + a; }
+    auto query(custom_query_t<0>, int a) const noexcept { return this->value + a; }
+    auto query(custom_query_t<2>, int a) const noexcept { return this->value + a; }
 };
 
 struct test_sender {
diff --git a/tests/beman/execution/exec-snd-transform.test.cpp b/tests/beman/execution/exec-snd-transform.test.cpp
index 814e92df..168700ea 100644
--- a/tests/beman/execution/exec-snd-transform.test.cpp
+++ b/tests/beman/execution/exec-snd-transform.test.cpp
@@ -1,6 +1,9 @@
 // src/beman/execution/tests/exec-snd-transform.test.cpp            -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -9,9 +12,6 @@ import beman.execution;
 #include <beman/execution/execution.hpp>
 #include <beman/execution/detail/tag_of_t.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <type_traits>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-starts-on.test.cpp b/tests/beman/execution/exec-starts-on.test.cpp
index 78d3ea49..af325ecb 100644
--- a/tests/beman/execution/exec-starts-on.test.cpp
+++ b/tests/beman/execution/exec-starts-on.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/exec-starts-on.test.cpp                -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/detail/starts_on.hpp>
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-sync-wait.test.cpp b/tests/beman/execution/exec-sync-wait.test.cpp
index 73cbdb42..489bb0a7 100644
--- a/tests/beman/execution/exec-sync-wait.test.cpp
+++ b/tests/beman/execution/exec-sync-wait.test.cpp
@@ -1,17 +1,16 @@
 // src/beman/execution/tests/exec-sync-wait.test.cpp                -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <exception>
+#include <concepts>
+#include <utility>
+#include <tuple>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <beman/execution/detail/sync_wait.hpp>
-#include <test/execution.hpp>
-
-#include <exception>
-#include <concepts>
-#include <utility>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-then.test.cpp b/tests/beman/execution/exec-then.test.cpp
index 9e9e8234..4a285478 100644
--- a/tests/beman/execution/exec-then.test.cpp
+++ b/tests/beman/execution/exec-then.test.cpp
@@ -1,6 +1,12 @@
 // src/beman/execution/tests/exec-then.test.cpp                     -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <memory_resource>
+#include <optional>
+#include <tuple>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -15,9 +21,6 @@ import beman.execution;
 #include <beman/execution/detail/start.hpp>
 #include <beman/execution/detail/sync_wait.hpp>
 #endif
-#include <concepts>
-#include <memory_resource>
-#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/exec-when-all.test.cpp b/tests/beman/execution/exec-when-all.test.cpp
index 2da62207..900aec66 100644
--- a/tests/beman/execution/exec-when-all.test.cpp
+++ b/tests/beman/execution/exec-when-all.test.cpp
@@ -1,6 +1,13 @@
 // src/beman/execution/tests/exec-when-all.test.cpp                 -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <optional>
+#include <utility>
+#include <tuple>
+#include <variant>
+// #include <beman/execution/detail/suppress_push.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
@@ -9,12 +16,6 @@ import beman.execution;
 #include <beman/execution/detail/when_all_with_variant.hpp>
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <concepts>
-#include <optional>
-#include <utility>
-
-#include <beman/execution/detail/suppress_push.hpp>
 
 // ----------------------------------------------------------------------------
 
@@ -71,7 +72,7 @@ struct await_cancel {
         using stop_callback = test_std::stop_callback_for_t<token, callback>;
 
         Receiver                     receiver;
-        std::optional<stop_callback> cb;
+        std::optional<stop_callback> cb{};
         auto                         start() & noexcept {
             cb.emplace(test_std::get_stop_token(test_std::get_env(this->receiver)), &this->receiver);
         }
diff --git a/tests/beman/execution/exec-with-awaitable-senders.test.cpp b/tests/beman/execution/exec-with-awaitable-senders.test.cpp
index 2b34a2c7..083e0d7a 100644
--- a/tests/beman/execution/exec-with-awaitable-senders.test.cpp
+++ b/tests/beman/execution/exec-with-awaitable-senders.test.cpp
@@ -1,14 +1,13 @@
 // src/beman/execution/tests/exec-with-awaitable-senders.test.cpp   -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <coroutine>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-
-#include <coroutine>
 
 // This examples shows how to await on senders
 // but also how to use awaitables with sender algorithms
diff --git a/tests/beman/execution/execution-queryable-concept.test.cpp b/tests/beman/execution/execution-queryable-concept.test.cpp
index da186d39..e5a6cf8b 100644
--- a/tests/beman/execution/execution-queryable-concept.test.cpp
+++ b/tests/beman/execution/execution-queryable-concept.test.cpp
@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <beman/execution/execution.hpp>
-#include "test/execution.hpp"
+#include <test/execution.hpp>
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/function-objects.test.cpp b/tests/beman/execution/function-objects.test.cpp
index 4cb5b873..bbce2161 100644
--- a/tests/beman/execution/function-objects.test.cpp
+++ b/tests/beman/execution/function-objects.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/function-objects.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
 
 TEST(function_objects) {
     // section [function.objects] is empty
diff --git a/tests/beman/execution/functional-syn.test.cpp b/tests/beman/execution/functional-syn.test.cpp
index e3d0e78d..6b6d8739 100644
--- a/tests/beman/execution/functional-syn.test.cpp
+++ b/tests/beman/execution/functional-syn.test.cpp
@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <beman/execution/functional.hpp>
-#include "test/execution.hpp"
+#include <test/execution.hpp>
 #include <concepts>
 
 // ----------------------------------------------------------------------------
diff --git a/tests/beman/execution/include/test/inline_scheduler.hpp b/tests/beman/execution/include/test/inline_scheduler.hpp
index 694864fd..b6d133cc 100644
--- a/tests/beman/execution/include/test/inline_scheduler.hpp
+++ b/tests/beman/execution/include/test/inline_scheduler.hpp
@@ -1,11 +1,10 @@
 // tests/beman/execution/include/test/inline_scheduler.hpp            -*-C++-*-
-// ----------------------------------------------------------------------------
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-// ----------------------------------------------------------------------------
 
 #ifndef INCLUDED_TESTS_BEMAN_EXECUTION_INCLUDE_TEST_INLINE_SCHEDULER
 #define INCLUDED_TESTS_BEMAN_EXECUTION_INCLUDE_TEST_INLINE_SCHEDULER
 
+#if 0
 #include <beman/execution/detail/get_completion_scheduler.hpp>
 #include <beman/execution/detail/get_env.hpp>
 #include <beman/execution/detail/sender.hpp>
@@ -15,6 +14,7 @@
 #include <beman/execution/detail/scheduler.hpp>
 #include <beman/execution/detail/completion_signatures.hpp>
 #include <test/execution.hpp>
+#endif
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/include/test/stop_token.hpp b/tests/beman/execution/include/test/stop_token.hpp
index 2c573fe3..cb93287c 100644
--- a/tests/beman/execution/include/test/stop_token.hpp
+++ b/tests/beman/execution/include/test/stop_token.hpp
@@ -5,11 +5,6 @@
 #ifndef INCLUDED_TEST_STOP_TOKEN
 #define INCLUDED_TEST_STOP_TOKEN
 
-#ifdef BEMAN_HAS_MODULES
-import beman.execution;
-#else
-#include <beman/execution/stop_token.hpp>
-#endif
 #include <beman/execution/detail/immovable.hpp>
 #include <test/execution.hpp>
 
@@ -25,6 +20,11 @@ import beman.execution;
 #include <mutex>
 #include <ranges>
 #include <thread>
+#if false && defined(BEMAN_HAS_MODULES)
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 // ----------------------------------------------------------------------------
 
diff --git a/tests/beman/execution/issue-144.test.cpp b/tests/beman/execution/issue-144.test.cpp
index ecf2343a..a58086aa 100644
--- a/tests/beman/execution/issue-144.test.cpp
+++ b/tests/beman/execution/issue-144.test.cpp
@@ -1,12 +1,12 @@
 // tests/beman/execution/issue-144.test.cpp                           -*-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
 
 namespace bex = beman::execution;
 
diff --git a/tests/beman/execution/issue-174.test.cpp b/tests/beman/execution/issue-174.test.cpp
index dcdc3340..aa462d0d 100644
--- a/tests/beman/execution/issue-174.test.cpp
+++ b/tests/beman/execution/issue-174.test.cpp
@@ -1,14 +1,14 @@
 // tests/beman/execution/issue-174.test.cpp                            *-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <thread>
+#include <utility>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
-#include <thread>
-#include <utility>
 
 namespace ex = beman::execution;
 
diff --git a/tests/beman/execution/issue-186.test.cpp b/tests/beman/execution/issue-186.test.cpp
index 0233584f..623f1826 100644
--- a/tests/beman/execution/issue-186.test.cpp
+++ b/tests/beman/execution/issue-186.test.cpp
@@ -1,12 +1,12 @@
 // tests/beman/execution/issue-186.test.cpp                            *-C++-*-
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/execution.hpp>
 #endif
-#include <test/execution.hpp>
 
 namespace ex = beman::execution;
 
diff --git a/tests/beman/execution/stopcallback-cons.test.cpp b/tests/beman/execution/stopcallback-cons.test.cpp
index 8549a9d1..4212f735 100644
--- a/tests/beman/execution/stopcallback-cons.test.cpp
+++ b/tests/beman/execution/stopcallback-cons.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/stopcallback-cons.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <memory>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include <memory>
-#include <type_traits>
 
 TEST(stopcallback_cons) {
     // Reference: [stopcallback.cons] p1
diff --git a/tests/beman/execution/stopcallback-general.test.cpp b/tests/beman/execution/stopcallback-general.test.cpp
index 52cba985..7bd73d7c 100644
--- a/tests/beman/execution/stopcallback-general.test.cpp
+++ b/tests/beman/execution/stopcallback-general.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/stopcallback-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include <concepts>
-#include <type_traits>
 
 namespace {
 auto test_stop_callback_interface() -> void {
diff --git a/tests/beman/execution/stopcallback-inplace-cons.test.cpp b/tests/beman/execution/stopcallback-inplace-cons.test.cpp
index e24cd244..d0010e45 100644
--- a/tests/beman/execution/stopcallback-inplace-cons.test.cpp
+++ b/tests/beman/execution/stopcallback-inplace-cons.test.cpp
@@ -1,12 +1,13 @@
 // src/beman/execution/tests/stopcallback-inplace-cons.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 namespace {
 auto test_inplace_stopcallback_ctor() -> void {
diff --git a/tests/beman/execution/stopcallback-inplace-general.test.cpp b/tests/beman/execution/stopcallback-inplace-general.test.cpp
index cd5552ce..49816ff9 100644
--- a/tests/beman/execution/stopcallback-inplace-general.test.cpp
+++ b/tests/beman/execution/stopcallback-inplace-general.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/stopcallback-inplace-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <concepts>
+#include <type_traits>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include <concepts>
-#include <type_traits>
 
 TEST(stopcallback_inplace_general) {
     // Reference: [stopcallback.inplace.general]
diff --git a/tests/beman/execution/stopcallback-inplace.test.cpp b/tests/beman/execution/stopcallback-inplace.test.cpp
index f56a5045..87124880 100644
--- a/tests/beman/execution/stopcallback-inplace.test.cpp
+++ b/tests/beman/execution/stopcallback-inplace.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/stopcallback-inplace.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 TEST(stopcallback_inplace) {
     // section [stopcallback.inplace] is empty
diff --git a/tests/beman/execution/stopcallback.test.cpp b/tests/beman/execution/stopcallback.test.cpp
index 827398ac..bafe64af 100644
--- a/tests/beman/execution/stopcallback.test.cpp
+++ b/tests/beman/execution/stopcallback.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/stopcallback.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include <test/execution.hpp>
 
 TEST(stopcallback) {
     // section [stopcallback] is empty
diff --git a/tests/beman/execution/stopsource-cons.test.cpp b/tests/beman/execution/stopsource-cons.test.cpp
index 9322d5bf..0b364bb7 100644
--- a/tests/beman/execution/stopsource-cons.test.cpp
+++ b/tests/beman/execution/stopsource-cons.test.cpp
@@ -1,17 +1,17 @@
 // src/beman/execution/tests/stopsource-cons.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifdef BEMAN_HAS_MODULES
-import beman.execution;
-#else
-#include <beman/execution/stop_token.hpp>
-#endif
-#include "test/execution.hpp"
+#include <test/execution.hpp>
 #include <new>
 #include <stdexcept>
 #include <cassert>
 #include <cstddef>
 #include <cstring>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 namespace {
 bool fail{};
diff --git a/tests/beman/execution/stopsource-general.test.cpp b/tests/beman/execution/stopsource-general.test.cpp
index ae9f2442..c181f05e 100644
--- a/tests/beman/execution/stopsource-general.test.cpp
+++ b/tests/beman/execution/stopsource-general.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/stopsource-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifdef BEMAN_HAS_MODULES
+#include <test/execution.hpp>
+#include <test/stop_token.hpp>
+#include <cassert>
+#if false && defined(BEMAN_HAS_MODULES)
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include "test/stop_token.hpp"
-#include <cassert>
 
 TEST(stopsource_general) {
     try {
diff --git a/tests/beman/execution/stopsource-inplace-cons.test.cpp b/tests/beman/execution/stopsource-inplace-cons.test.cpp
index 5650a933..786bab4e 100644
--- a/tests/beman/execution/stopsource-inplace-cons.test.cpp
+++ b/tests/beman/execution/stopsource-inplace-cons.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/stopsource-inplace-cons.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <cassert>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include <cassert>
 
 TEST(stopsource_inplace_cons) {
     // Plan:
diff --git a/tests/beman/execution/stopsource-inplace-general.test.cpp b/tests/beman/execution/stopsource-inplace-general.test.cpp
index 6a684dc0..e7f813a1 100644
--- a/tests/beman/execution/stopsource-inplace-general.test.cpp
+++ b/tests/beman/execution/stopsource-inplace-general.test.cpp
@@ -1,9 +1,13 @@
 // src/beman/execution/tests/stopsource-inplace-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <test/stop_token.hpp>
+#if false && defined(BEMAN_HAS_MODULES)
+import beman.execution;
+#else
 #include <beman/execution/stop_token.hpp>
-#include "test/execution.hpp"
-#include "test/stop_token.hpp"
+#endif
 
 TEST(stopsource_inplace_general) {
     // Reference: [stopsource.inplace.general]
diff --git a/tests/beman/execution/stopsource-inplace-mem.test.cpp b/tests/beman/execution/stopsource-inplace-mem.test.cpp
index 829c3848..b5ca35b4 100644
--- a/tests/beman/execution/stopsource-inplace-mem.test.cpp
+++ b/tests/beman/execution/stopsource-inplace-mem.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/stopsource-inplace-mem.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 namespace {
 auto test_inplace_stop_source_get_token() -> void {
diff --git a/tests/beman/execution/stopsource-inplace.test.cpp b/tests/beman/execution/stopsource-inplace.test.cpp
index fef20312..7dab8cdf 100644
--- a/tests/beman/execution/stopsource-inplace.test.cpp
+++ b/tests/beman/execution/stopsource-inplace.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/stopsource-inplace.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(stopsource_inplace) {
     // section [stopsource.inplace] is empty
diff --git a/tests/beman/execution/stopsource-mem.test.cpp b/tests/beman/execution/stopsource-mem.test.cpp
index 2a605f59..5a2e4e28 100644
--- a/tests/beman/execution/stopsource-mem.test.cpp
+++ b/tests/beman/execution/stopsource-mem.test.cpp
@@ -1,12 +1,13 @@
 // src/beman/execution/tests/stopsource-mem.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <memory>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 namespace {
 auto test_stopsource_swap() -> void {
diff --git a/tests/beman/execution/stopsource.test.cpp b/tests/beman/execution/stopsource.test.cpp
index 7ca9ba20..74882c42 100644
--- a/tests/beman/execution/stopsource.test.cpp
+++ b/tests/beman/execution/stopsource.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/stopsource.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(stopsource) {
     // section [thread] is empty
diff --git a/tests/beman/execution/stoptoken-concepts.test.cpp b/tests/beman/execution/stoptoken-concepts.test.cpp
index fa7bdeaa..748d1552 100644
--- a/tests/beman/execution/stoptoken-concepts.test.cpp
+++ b/tests/beman/execution/stoptoken-concepts.test.cpp
@@ -1,9 +1,9 @@
 // src/beman/execution/tests/stoptoken-concepts.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/stop_token.hpp>
 #include <type_traits>
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#include <beman/execution/stop_token.hpp>
 
 namespace {
 namespace detail_stopppable_callback_for {
diff --git a/tests/beman/execution/stoptoken-general.test.cpp b/tests/beman/execution/stoptoken-general.test.cpp
index 501dced4..40a59e7b 100644
--- a/tests/beman/execution/stoptoken-general.test.cpp
+++ b/tests/beman/execution/stoptoken-general.test.cpp
@@ -1,13 +1,13 @@
 // src/beman/execution/tests/stoptoken-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifdef BEMAN_HAS_MODULES
+#include <test/execution.hpp>
+#include <test/stop_token.hpp>
+#if false && defined(BEMAN_HAS_MODULES)
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include "test/stop_token.hpp"
 
 TEST(stoptoken_general) {
     // [stoptoken.general] p1:
diff --git a/tests/beman/execution/stoptoken-inplace-general.test.cpp b/tests/beman/execution/stoptoken-inplace-general.test.cpp
index 552e40b5..241455bb 100644
--- a/tests/beman/execution/stoptoken-inplace-general.test.cpp
+++ b/tests/beman/execution/stoptoken-inplace-general.test.cpp
@@ -1,14 +1,14 @@
 // src/beman/execution/tests/stoptoken-inplace-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
+#include <type_traits>
+#include <cassert>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
-#include <type_traits>
-#include <cassert>
 
 TEST(stoptoken_inplace_general) {
     // Reference [stoptoken.inplace.general]
diff --git a/tests/beman/execution/stoptoken-inplace-members.test.cpp b/tests/beman/execution/stoptoken-inplace-members.test.cpp
index 4115289b..4d7e7a7c 100644
--- a/tests/beman/execution/stoptoken-inplace-members.test.cpp
+++ b/tests/beman/execution/stoptoken-inplace-members.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/stoptoken-inplace-members.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 namespace {
 auto test_inplace_stop_token_swap() -> void {
diff --git a/tests/beman/execution/stoptoken-inplace.test.cpp b/tests/beman/execution/stoptoken-inplace.test.cpp
index c5ec660c..3adc807b 100644
--- a/tests/beman/execution/stoptoken-inplace.test.cpp
+++ b/tests/beman/execution/stoptoken-inplace.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/stoptoken-inplace.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(stoptoken_inplace) {
     // section [stoptoken.inplace] is empty
diff --git a/tests/beman/execution/stoptoken-mem.test.cpp b/tests/beman/execution/stoptoken-mem.test.cpp
index 2b1836fa..1939d3a3 100644
--- a/tests/beman/execution/stoptoken-mem.test.cpp
+++ b/tests/beman/execution/stoptoken-mem.test.cpp
@@ -1,15 +1,15 @@
 // src/beman/execution/tests/stoptoken-mem.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#ifdef BEMAN_HAS_MODULES
+#include <array>
+#include <memory>
+#include <test/execution.hpp>
+#include <test/stop_token.hpp>
+#if false && defined(BEMAN_HAS_MODULES)
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include <array>
-#include <memory>
-#include "test/execution.hpp"
-#include "test/stop_token.hpp"
 
 namespace {
 auto test_stop_token_swap() -> void {
diff --git a/tests/beman/execution/stoptoken-never-general.test.cpp b/tests/beman/execution/stoptoken-never-general.test.cpp
index 148cd5e6..c3c62a56 100644
--- a/tests/beman/execution/stoptoken-never-general.test.cpp
+++ b/tests/beman/execution/stoptoken-never-general.test.cpp
@@ -1,12 +1,12 @@
 // src/beman/execution/tests/stoptoken-never-general.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #ifdef BEMAN_HAS_MODULES
 import beman.execution;
 #else
 #include <beman/execution/stop_token.hpp>
 #endif
-#include "test/execution.hpp"
 
 TEST(stoptoken_never_general) {
     // Reference: [stoptoken.never.general]
diff --git a/tests/beman/execution/stoptoken-never.test.cpp b/tests/beman/execution/stoptoken-never.test.cpp
index abb8f0c9..e4fe5c72 100644
--- a/tests/beman/execution/stoptoken-never.test.cpp
+++ b/tests/beman/execution/stoptoken-never.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/stoptoken-never.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(stoptoken_never) {
     // section [stoptoken.never] is empty
diff --git a/tests/beman/execution/stoptoken.test.cpp b/tests/beman/execution/stoptoken.test.cpp
index b1a5250b..0518e6aa 100644
--- a/tests/beman/execution/stoptoken.test.cpp
+++ b/tests/beman/execution/stoptoken.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/stoptoken.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(stoptoken) {
     // section [stoptoken] is empty
diff --git a/tests/beman/execution/thread-stoptoken-intro.test.cpp b/tests/beman/execution/thread-stoptoken-intro.test.cpp
index 45b1351c..7d68b80c 100644
--- a/tests/beman/execution/thread-stoptoken-intro.test.cpp
+++ b/tests/beman/execution/thread-stoptoken-intro.test.cpp
@@ -1,11 +1,15 @@
 // src/beman/execution/tests/thread-stoptoken-intro.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include <beman/execution/stop_token.hpp>
 #include <beman/execution/detail/immovable.hpp>
-#include "test/execution.hpp"
-#include "test/stop_token.hpp"
+#include <test/execution.hpp>
+#include <test/stop_token.hpp>
 #include <utility>
+#if false && defined(BEMAN_HAS_MODULES)
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 namespace {
 struct test_source : test_detail::immovable {
diff --git a/tests/beman/execution/thread-stoptoken-syn.compile.test.cpp b/tests/beman/execution/thread-stoptoken-syn.compile.test.cpp
index 0c1bfef0..0e2b36ad 100644
--- a/tests/beman/execution/thread-stoptoken-syn.compile.test.cpp
+++ b/tests/beman/execution/thread-stoptoken-syn.compile.test.cpp
@@ -1,8 +1,8 @@
 // src/beman/execution/tests/thread-stoptoken-syn.compile.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <test/execution.hpp>
 #include <beman/execution/stop_token.hpp>
-#include "test/execution.hpp"
 
 namespace {
 template <typename>
diff --git a/tests/beman/execution/thread-stoptoken.test.cpp b/tests/beman/execution/thread-stoptoken.test.cpp
index f65d973f..fe257c21 100644
--- a/tests/beman/execution/thread-stoptoken.test.cpp
+++ b/tests/beman/execution/thread-stoptoken.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/thread-stoptoken.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(thread_stoptoken) {
     // section [thread.stoptoken] is empty
diff --git a/tests/beman/execution/thread.test.cpp b/tests/beman/execution/thread.test.cpp
index a432840f..d57184e9 100644
--- a/tests/beman/execution/thread.test.cpp
+++ b/tests/beman/execution/thread.test.cpp
@@ -1,7 +1,12 @@
 // src/beman/execution/tests/thread.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#else
+#include <beman/execution/stop_token.hpp>
+#endif
 
 TEST(thread) {
     // section [thread] is empty
diff --git a/tests/beman/execution/utilities.test.cpp b/tests/beman/execution/utilities.test.cpp
index f826c849..1cdf019e 100644
--- a/tests/beman/execution/utilities.test.cpp
+++ b/tests/beman/execution/utilities.test.cpp
@@ -1,7 +1,10 @@
 // src/beman/execution/tests/utilities.test.cpp
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-#include "test/execution.hpp"
+#include <test/execution.hpp>
+#ifdef BEMAN_HAS_MODULES
+import beman.execution;
+#endif
 
 TEST(utilities) {
     // section [utilities] is empty