diff --git a/docs/dev/clang-tidy-fixes-2026-04.md b/docs/dev/clang-tidy-fixes-2026-04.md
index 66c4174f..75a942ea 100644
--- a/docs/dev/clang-tidy-fixes-2026-04.md
+++ b/docs/dev/clang-tidy-fixes-2026-04.md
@@ -90,9 +90,6 @@
   - [PR #560](https://github.com/Framework-R-D/phlex/pull/560)
 - [x] [cppcoreguidelines-use-default-member-init](https://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/use-default-member-init.html) (5)
   - [PR #556](https://github.com/Framework-R-D/phlex/pull/556)
-- [x] [google-explicit-constructor](https://clang.llvm.org/extra/clang-tidy/checks/google/explicit-constructor.html) (38)
-  - _a.k.a._ [misc-explicit-constructor](https://clang.llvm.org/extra/clang-tidy/checks/misc/explicit-constructor.html) (`clang-tidy` >= 23.0.0)
-  - [PR #581](https://github.com/Framework-R-D/phlex/pull/581)
 - [ ] [modernize-avoid-c-arrays](https://clang.llvm.org/extra/clang-tidy/checks/modernize/avoid-c-arrays.html) (17)
 - [ ] [modernize-avoid-c-style-cast](https://clang.llvm.org/extra/clang-tidy/checks/modernize/avoid-c-style-cast.html) (82)
 - [ ] [modernize-concat-nested-namespaces](https://clang.llvm.org/extra/clang-tidy/checks/modernize/concat-nested-namespaces.html) (1)
@@ -104,32 +101,27 @@
 - [ ] [modernize-use-designated-initializers](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-designated-initializers.html) (69)
 - [ ] [modernize-use-equals-default](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-equals-default.html) (7)
 - [ ] [modernize-use-integer-sign-comparison](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-integer-sign-comparison.html) (7)
-- [x] [modernize-use-nullptr](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-nullptr.html) (194)
-  - [PR #592](https://github.com/Framework-R-D/phlex/pull/592)
+- [ ] [modernize-use-nullptr](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-nullptr.html) (194)
 - [ ] [modernize-use-ranges](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-ranges.html) (5)
 - [ ] [modernize-use-starts-ends-with](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-starts-ends-with.html) (6)
 - [ ] [modernize-use-std-numbers](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-std-numbers.html) (2)
 - [ ] [modernize-use-using](https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-using.html) (3)
 - [x] [performance-avoid-endl](https://clang.llvm.org/extra/clang-tidy/checks/performance/avoid-endl.html) (27)
   - [PR #563](https://github.com/Framework-R-D/phlex/pull/563)
-- [x] [performance-enum-size](https://clang.llvm.org/extra/clang-tidy/checks/performance/enum-size.html) (2)
-  - [PR #583](https://github.com/Framework-R-D/phlex/pull/583)
+- [ ] [performance-enum-size](https://clang.llvm.org/extra/clang-tidy/checks/performance/enum-size.html) (2)
 - [x] [performance-faster-string-find](https://clang.llvm.org/extra/clang-tidy/checks/performance/faster-string-find.html) (4)
   - [PR #584](https://github.com/Framework-R-D/phlex/pull/584)
-- [ ] [performance-inefficient-string-concatenation](https://clang.llvm.org/extra/clang-tidy/checks/performance/inefficient-string-concatenation.html) (2)
-- [x] [performance-inefficient-vector-operation](https://clang.llvm.org/extra/clang-tidy/checks/performance/inefficient-vector-operation.html) (1)
-  - [PR #586](https://github.com/Framework-R-D/phlex/pull/586)
+- [x] [performance-inefficient-string-concatenation](https://clang.llvm.org/extra/clang-tidy/checks/performance/inefficient-string-concatenation.html) (2)
+  - [PR #585](https://github.com/Framework-R-D/phlex/pull/585)
+- [ ] [performance-inefficient-vector-operation](https://clang.llvm.org/extra/clang-tidy/checks/performance/inefficient-vector-operation.html) (1)
 - [ ] [performance-move-const-arg](https://clang.llvm.org/extra/clang-tidy/checks/performance/move-const-arg.html) (1)
 - [ ] [performance-no-automatic-move](https://clang.llvm.org/extra/clang-tidy/checks/performance/no-automatic-move.html) (1)
 - [x] [performance-no-int-to-ptr](https://clang.llvm.org/extra/clang-tidy/checks/performance/no-int-to-ptr.html) (15)
   - [PR #564](https://github.com/Framework-R-D/phlex/pull/564)
-- [x] [performance-type-promotion-in-math-fn](https://clang.llvm.org/extra/clang-tidy/checks/performance/type-promotion-in-math-fn.html) (2)
-  - Resolved incidentally by [PR #551](https://github.com/Framework-R-D/phlex/pull/551)
-- [x] [performance-unnecessary-copy-initialization](https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-copy-initialization.html) (1)
-  - [PR #590](https://github.com/Framework-R-D/phlex/pull/590)
+- [ ] [performance-type-promotion-in-math-fn](https://clang.llvm.org/extra/clang-tidy/checks/performance/type-promotion-in-math-fn.html) (2)
+- [ ] [performance-unnecessary-copy-initialization](https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-copy-initialization.html) (1)
 - [ ] [performance-unnecessary-value-param](https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-value-param.html) (44)
-- [x] [portability-template-virtual-member-function](https://clang.llvm.org/extra/clang-tidy/checks/portability/template-virtual-member-function.html) (2)
-  - [PR #591](https://github.com/Framework-R-D/phlex/pull/591)
+- [ ] [portability-template-virtual-member-function](https://clang.llvm.org/extra/clang-tidy/checks/portability/template-virtual-member-function.html) (2)
 - [ ] [readability-avoid-const-params-in-decls](https://clang.llvm.org/extra/clang-tidy/checks/readability/avoid-const-params-in-decls.html) (7)
 - [ ] [readability-braces-around-statements](https://clang.llvm.org/extra/clang-tidy/checks/readability/braces-around-statements.html) (74)
 - [ ] [readability-const-return-type](https://clang.llvm.org/extra/clang-tidy/checks/readability/const-return-type.html) (1)
diff --git a/phlex/core/framework_graph.cpp b/phlex/core/framework_graph.cpp
index f79f7cfc..1428de5e 100644
--- a/phlex/core/framework_graph.cpp
+++ b/phlex/core/framework_graph.cpp
@@ -4,11 +4,11 @@
 #include "phlex/core/edge_maker.hpp"
 #include "phlex/model/product_store.hpp"
 
-#include "fmt/std.h"
 #include "spdlog/cfg/env.h"
 #include "spdlog/spdlog.h"
 
 #include <cassert>
+#include <format>
 #include <iostream>
 
 namespace phlex::experimental {
@@ -120,8 +120,8 @@ namespace phlex::experimental {
             make_edge(predicate->sender(), it->second.predicate_port());
             continue;
           }
-          throw std::runtime_error("A non-existent filter with the name '" + predicate_name +
-                                   "' was specified for " + name);
+          throw std::runtime_error(std::format(
+            "A non-existent filter with the name '{}' was specified for {}", predicate_name, name));
         }
       }
       return result;
diff --git a/plugins/python/src/pymodule.cpp b/plugins/python/src/pymodule.cpp
index 6e4e3df0..e915ab02 100644
--- a/plugins/python/src/pymodule.cpp
+++ b/plugins/python/src/pymodule.cpp
@@ -120,9 +120,8 @@ static void add_cmake_prefix_paths_to_syspath(char const* cmake_prefix_path)
   // Build site-packages paths from each CMAKE_PREFIX_PATH token
   while (std::getline(iss, path_entry, ':')) {
     if (!path_entry.empty()) {
-      std::string version_str =
-        std::to_string(PY_MAJOR_VERSION) + "." + std::to_string(PY_MINOR_VERSION);
-      std::string site_packages = path_entry + "/lib/python" + version_str + "/site-packages";
+      std::string site_packages = path_entry + "/lib/python" + std::to_string(PY_MAJOR_VERSION) +
+                                  "." + std::to_string(PY_MINOR_VERSION) + "/site-packages";
       site_package_paths.push_back(site_packages);
     }
   }
diff --git a/test/framework_graph.cpp b/test/framework_graph.cpp
index ae4cd095..5ac65653 100644
--- a/test/framework_graph.cpp
+++ b/test/framework_graph.cpp
@@ -3,6 +3,7 @@
 #include "plugins/layer_generator.hpp"
 
 #include "catch2/catch_test_macros.hpp"
+#include "catch2/matchers/catch_matchers_string.hpp"
 
 #include <stdexcept>
 
@@ -78,3 +79,26 @@ TEST_CASE("Stop driver when workflow throws exception", "[graph]")
   CHECK(g.execution_count("throw_exception") == 0ull);
   CHECK(g.execution_count("downstream_of_exception") == 0ull);
 }
+
+TEST_CASE("Throw when predicate specified by consumer does not exist", "[graph]")
+{
+  experimental::layer_generator gen;
+  gen.add_layer("event", {"job", 1, 1});
+
+  experimental::framework_graph g{driver_for_test(gen)};
+  g.provide(
+     "provide_num",
+     [](data_cell_index const& id) -> unsigned int { return id.number(); },
+     concurrency::unlimited)
+    .output_product("input", "num", "event");
+
+  g.observe(
+     "observe_num", [](unsigned int const) {}, concurrency::unlimited)
+    .input_family(product_query{.creator = "input", .layer = "event", .suffix = "num"})
+    .experimental_when("missing_predicate");
+
+  CHECK_THROWS_WITH(
+    g.execute(),
+    Catch::Matchers::ContainsSubstring(
+      "A non-existent filter with the name 'missing_predicate' was specified for observe_num"));
+}