@@ -32,6 +32,9 @@ typedef struct {
     PyDictValues *ma_values;
 } PyDictObject;
 
+#define PyAnyDict_CheckExact(ob) PyDict_CheckExact(ob)
+#define PyAnyDict_Check(ob) PyDict_Check(ob)
+
 PyAPI_FUNC(PyObject *) _PyDict_GetItem_KnownHash(PyObject *mp, PyObject *key,
                                                  Py_hash_t hash);
 // PyDict_GetItemStringRef() can be used instead
 
@@ -316,6 +316,7 @@ PyAPI_FUNC(void) _PyObjectArray_Free(PyObject **array, PyObject **scratch);
 
 PyAPI_FUNC(PyObject *) _PyEval_GetANext(PyObject *aiter);
 PyAPI_FUNC(void) _PyEval_LoadGlobalStackRef(PyObject *globals, PyObject *builtins, PyObject *name, _PyStackRef *writeto);
+PyAPI_FUNC(PyObject*) _PyMapping_GetOptionalItem2(PyObject *obj, PyObject *key, int *err);
 PyAPI_FUNC(PyObject *) _PyEval_GetAwaitable(PyObject *iterable, int oparg);
 PyAPI_FUNC(PyObject *) _PyEval_LoadName(PyThreadState *tstate, _PyInterpreterFrame *frame, PyObject *name);
 PyAPI_FUNC(int)
 
@@ -23,6 +23,11 @@ PyAPI_FUNC(int) _PyDict_DelItemIf(PyObject *mp, PyObject *key,
                                   int (*predicate)(PyObject *value, void *arg),
                                   void *arg);
 
+// Atomically replace an existing value if it is expected (by identity).
+// Return 1 if replaced, 0 if absent or different, or -1 on error.
+extern int _PyDict_ReplaceItemIf(PyObject *dict, PyObject *key,
+                               PyObject *expected, PyObject *replacement);
+
 // "KnownHash" variants
 // Export for '_asyncio' shared extension
 PyAPI_FUNC(int) _PyDict_SetItem_KnownHash(PyObject *mp, PyObject *key,
@@ -134,10 +139,10 @@ extern Py_ssize_t _PyDictKeys_StringLookup(PyDictKeysObject* dictkeys, PyObject
  *
  * Returns DKIX_EMPTY if the key is not present.
  */
-extern Py_ssize_t _PyDictKeys_StringLookupAndVersion(PyDictKeysObject* dictkeys, PyObject *key, uint32_t *version);
-extern Py_ssize_t _PyDictKeys_StringLookupSplit(PyDictKeysObject* dictkeys, PyObject *key);
-PyAPI_FUNC(PyObject *)_PyDict_LoadGlobal(PyDictObject *, PyDictObject *, PyObject *);
-PyAPI_FUNC(void) _PyDict_LoadGlobalStackRef(PyDictObject *, PyDictObject *, PyObject *, _PyStackRef *);
+PyAPI_FUNC(Py_ssize_t) _PyDictKeys_StringLookupAndVersion(PyDictKeysObject* dictkeys, PyObject *key, uint32_t *version);
+PyAPI_FUNC(Py_ssize_t) _PyDictKeys_StringLookupSplit(PyDictKeysObject* dictkeys, PyObject *key);
+// Return the borrowed source dictionary, or NULL if absent or on error.
+PyAPI_FUNC(PyObject *) _PyDict_LoadGlobalStackRef(PyDictObject *, PyDictObject *, PyObject *, _PyStackRef *);
 
 // Loads the __builtins__ object from the globals dict. Returns a new reference.
 extern PyObject *_PyDict_LoadBuiltinsFromGlobals(PyObject *globals);
 
@@ -17,7 +17,6 @@ typedef struct {
     int mode;
     int startup_mode;
     PyObject *filter;
-    PyObject *importing_modules;
     PyObject *modules;
     PyObject *pending_submodules;
     PyObject *builtins_import_name;
@@ -54,20 +53,16 @@ extern int _PyImport_FixupBuiltin(
     PyObject *modules
     );
 
-extern PyObject * _PyImport_ResolveName(
-    PyThreadState *tstate, PyObject *name, PyObject *globals, int level);
 extern PyObject * _PyImport_GetAbsName(
     PyThreadState *tstate, PyObject *name, PyObject *globals, int level);
 // Symbol is exported for the JIT on Windows builds.
 PyAPI_FUNC(PyObject *) _PyImport_LoadLazyImportTstate(
     PyThreadState *tstate, PyObject *lazy_import);
-typedef enum {
-    _Py_LAZY_SUBMODULE_ERROR = -1,
-    _Py_LAZY_SUBMODULE_NOT_FOUND = 0,
-    _Py_LAZY_SUBMODULE_LOADED = 1,
-} _PyLazySubmoduleImportResult;
-extern _PyLazySubmoduleImportResult _PyImport_TryLoadLazySubmodule(
-    PyObject *mod_name, PyObject *attr_name, PyObject **result);
+// Bind a pending child on module before removing its registration. Return a
+// new reference, NULL without an exception if absent, or NULL on error.
+// Set recheck_dict if a concurrent lookup may have already bound the child.
+extern PyObject * _PyImport_TryLoadLazySubmodule(
+    PyObject *module, PyObject *attr_name, int *recheck_dict);
 extern PyObject * _PyImport_LazyImportModuleLevelObject(
     PyThreadState *tstate, PyObject *name, PyObject *builtins,
     PyObject *globals, PyObject *locals, PyObject *fromlist, int level);
 
@@ -14,20 +14,18 @@ extern "C" {
 PyAPI_DATA(PyTypeObject) PyLazyImport_Type;
 #define PyLazyImport_CheckExact(op) Py_IS_TYPE((op), &PyLazyImport_Type)
 
-typedef struct {
-    PyObject_HEAD
-    PyObject *lz_builtins;
-    PyObject *lz_from;
-    PyObject *lz_attr;
-    // Frame information for the original import location.
-    PyCodeObject *lz_code;     // Code object where the lazy import was created.
-    int lz_instr_offset;       // Instruction offset where the lazy import was created.
-} PyLazyImportObject;
-
-
-PyAPI_FUNC(PyObject *) _PyLazyImport_GetName(PyObject *lazy_import);
 PyAPI_FUNC(PyObject *) _PyLazyImport_New(
-    struct _PyInterpreterFrame *frame, PyObject *import_func, PyObject *from, PyObject *attr);
+    struct _PyInterpreterFrame *frame, PyObject *builtins,
+    PyObject *name, PyObject *fromlist);
+
+extern int _PyLazyImport_IsResolving(PyThreadState *tstate, PyObject *op);
+
+// Resolve a placeholder and replace its binding if it is unchanged or holds
+// the child module published by the normal importer during resolution.
+// namespace is the source captured during lookup, before resolution runs.
+PyAPI_FUNC(PyObject *) _PyLazyImport_Reify(
+    PyThreadState *tstate, PyObject *placeholder,
+    PyObject *name, PyObject *ns);
 
 #ifdef __cplusplus
 }
 
@@ -83,7 +83,10 @@ typedef struct _PyThreadStateImpl {
 #ifdef Py_GIL_DISABLED
     // gh-144438: Add padding to ensure that the fields above don't share a
     // cache line with other allocations.
-    char __padding[64];
+    // Lazy-import placeholders in progress on this thread (GH-158282 backport).
+    // Carved from the reserved tail padding so sizeof stays byte-identical.
+    PyObject *lazy_imports;
+    char __padding[56];
 #endif
 } _PyThreadStateImpl;