diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5c8906451..36d564e78 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -101,20 +101,6 @@ jobs:
             python: '3.12'
             args: >
               -DCMAKE_CXX_FLAGS="/DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT /GR /EHsc"
-          # Exercise PYBIND11_SMART_HOLDER_DISABLE
-          # with recent (or ideally latest) released Python version.
-          - runs-on: ubuntu-latest
-            python: '3.12'
-            args: >
-              -DCMAKE_CXX_FLAGS="-DPYBIND11_SMART_HOLDER_DISABLE"
-          - runs-on: macos-13
-            python: '3.12'
-            args: >
-              -DCMAKE_CXX_FLAGS="-DPYBIND11_SMART_HOLDER_DISABLE"
-          - runs-on: windows-2022
-            python: '3.12'
-            args: >
-              -DCMAKE_CXX_FLAGS="/DPYBIND11_SMART_HOLDER_DISABLE /GR /EHsc"
         exclude:
           # The setup-python action currently doesn't have graalpy for windows
           - python: 'graalpy-24.1'
diff --git a/include/pybind11/attr.h b/include/pybind11/attr.h
index dc9570f92..5380fd555 100644
--- a/include/pybind11/attr.h
+++ b/include/pybind11/attr.h
@@ -339,9 +339,7 @@ struct type_record {
     /// Solves pybind/pybind11#1446
     bool release_gil_before_calling_cpp_dtor : 1;
 
-#ifdef PYBIND11_HAS_INTERNALS_WITH_SMART_HOLDER_SUPPORT
     holder_enum_t holder_enum_v = holder_enum_t::undefined;
-#endif
 
     PYBIND11_NOINLINE void add_base(const std::type_info &base, void *(*caster)(void *) ) {
         auto *base_info = detail::get_type_info(base, false);
diff --git a/include/pybind11/detail/common.h b/include/pybind11/detail/common.h
index eab3e1c0d..765812a4b 100644
--- a/include/pybind11/detail/common.h
+++ b/include/pybind11/detail/common.h
@@ -22,6 +22,8 @@
 // Additional convention: 0xD = dev
 #define PYBIND11_VERSION_HEX 0x030000D1
 
+#define PYBIND11_SMART_HOLDER_ENABLED // TODO(rwgk): purge
+
 // Define some generic pybind11 helper macros for warning management.
 //
 // Note that compiler-specific push/pop pairs are baked into the
@@ -605,11 +607,8 @@ struct instance {
     bool simple_instance_registered : 1;
     /// If true, get_internals().patients has an entry for this object
     bool has_patients : 1;
-// Cannot use PYBIND11_INTERNALS_VERSION >= 106 here without refactoring.
-#if PYBIND11_VERSION_MAJOR >= 3
     /// If true, this Python object needs to be kept alive for the lifetime of the C++ value.
     bool is_alias : 1;
-#endif
 
     /// Initializes all of the above type/values/holders data (but not the instance values
     /// themselves)
diff --git a/include/pybind11/detail/internals.h b/include/pybind11/detail/internals.h
index beba642aa..a206b17dd 100644
--- a/include/pybind11/detail/internals.h
+++ b/include/pybind11/detail/internals.h
@@ -37,15 +37,11 @@
 /// further ABI-incompatible changes may be made before the ABI is officially
 /// changed to the new version.
 #ifndef PYBIND11_INTERNALS_VERSION
-#    if PYBIND11_VERSION_MAJOR >= 3
-#        define PYBIND11_INTERNALS_VERSION 106
-#    else
-#        define PYBIND11_INTERNALS_VERSION 6
-#    endif
+#    define PYBIND11_INTERNALS_VERSION 7
 #endif
 
-#if PYBIND11_INTERNALS_VERSION < 6
-#    error "PYBIND11_INTERNALS_VERSION 6 is the minimum for all platforms for pybind11v3."
+#if PYBIND11_INTERNALS_VERSION < 7
+#    error "PYBIND11_INTERNALS_VERSION 7 is the minimum for all platforms for pybind11v3."
 #endif
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
@@ -215,10 +211,6 @@ struct internals {
     }
 };
 
-#if PYBIND11_INTERNALS_VERSION >= 106
-
-#    define PYBIND11_HAS_INTERNALS_WITH_SMART_HOLDER_SUPPORT
-
 enum class holder_enum_t : uint8_t {
     undefined,
     std_unique_ptr, // Default, lacking interop with std::shared_ptr.
@@ -227,13 +219,6 @@ enum class holder_enum_t : uint8_t {
     custom_holder,
 };
 
-#endif
-
-#if defined(PYBIND11_HAS_INTERNALS_WITH_SMART_HOLDER_SUPPORT)                                     \
-    && !defined(PYBIND11_SMART_HOLDER_DISABLE)
-#    define PYBIND11_SMART_HOLDER_ENABLED
-#endif
-
 /// Additional type information which does not fit into the PyTypeObject.
 /// Changes to this struct also require bumping `PYBIND11_INTERNALS_VERSION`.
 struct type_info {
@@ -262,9 +247,7 @@ struct type_info {
     bool default_holder : 1;
     /* true if this is a type registered with py::module_local */
     bool module_local : 1;
-#ifdef PYBIND11_HAS_INTERNALS_WITH_SMART_HOLDER_SUPPORT
     holder_enum_t holder_enum_v = holder_enum_t::undefined;
-#endif
 };
 
 #define PYBIND11_INTERNALS_ID                                                                     \
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index a09aafec6..dfbcbcf0f 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -1448,9 +1448,7 @@ protected:
         tinfo->simple_ancestors = true;
         tinfo->default_holder = rec.default_holder;
         tinfo->module_local = rec.module_local;
-#ifdef PYBIND11_HAS_INTERNALS_WITH_SMART_HOLDER_SUPPORT
         tinfo->holder_enum_v = rec.holder_enum_v;
-#endif
 
         with_internals([&](internals &internals) {
             auto tindex = std::type_index(*rec.type);