diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 459846e55ccf70..c286e3fc4f2bda 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1014,13 +1014,6 @@ symtable
   (Contributed by Yashp002 in :gh:`143504`.)
 
 
-symtable
---------
-
-* Add :meth:`symtable.Function.get_cells` and :meth:`symtable.Symbol.is_cell` methods.
-  (Contributed by Yashp002 in :gh:`143504`.)
-
-
 sys
 ---
 
diff --git a/Lib/base64.py b/Lib/base64.py
index 36688ce43917ce..dcfcbcc95a39be 100644
--- a/Lib/base64.py
+++ b/Lib/base64.py
@@ -100,7 +100,13 @@ def b64decode(s, altchars=None, validate=_NOT_SPECIFIED, *, ignorechars=_NOT_SPE
                     break
             s = s.translate(bytes.maketrans(altchars, b'+/'))
         else:
-            trans = bytes.maketrans(b'+/' + altchars, altchars + b'+/')
+            trans_in = set(b'+/') - set(altchars)
+            if len(trans_in) == 2:
+                # we can't use the reqult of unordered sets here
+                trans = bytes.maketrans(altchars + b'+/', b'+/' + altchars)
+            else:
+                trans = bytes.maketrans(altchars + bytes(trans_in),
+                                        b'+/' + bytes(set(altchars) - set(b'+/')))
             s = s.translate(trans)
             ignorechars = ignorechars.translate(trans)
     if ignorechars is _NOT_SPECIFIED:
diff --git a/Lib/test/test_base64.py b/Lib/test/test_base64.py
index 69aa628db7c34c..9648624b267a54 100644
--- a/Lib/test/test_base64.py
+++ b/Lib/test/test_base64.py
@@ -293,6 +293,13 @@ def test_b64decode_altchars(self):
             eq(base64.b64decode(data_str, altchars=altchars_str), res)
             eq(base64.b64decode(data, altchars=altchars, ignorechars=b'\n'), res)
 
+        eq(base64.b64decode(b'/----', altchars=b'-+', ignorechars=b'/'), b'\xfb\xef\xbe')
+        eq(base64.b64decode(b'/----', altchars=b'+-', ignorechars=b'/'), b'\xff\xff\xff')
+        eq(base64.b64decode(b'+----', altchars=b'-/', ignorechars=b'+'), b'\xfb\xef\xbe')
+        eq(base64.b64decode(b'+----', altchars=b'/-', ignorechars=b'+'), b'\xff\xff\xff')
+        eq(base64.b64decode(b'+/+/', altchars=b'/+', ignorechars=b''), b'\xff\xef\xfe')
+        eq(base64.b64decode(b'/+/+', altchars=b'+/', ignorechars=b''), b'\xff\xef\xfe')
+
         self.assertRaises(ValueError, base64.b64decode, b'', altchars=b'+')
         self.assertRaises(ValueError, base64.b64decode, b'', altchars=b'+/-')
         self.assertRaises(ValueError, base64.b64decode, '', altchars='+')
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index e106ac20809f20..5f035c35367d64 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -3,6 +3,7 @@
 # See test_cmd_line_script.py for testing of script execution
 
 import os
+import re
 import subprocess
 import sys
 import sysconfig
@@ -59,11 +60,22 @@ def test_help(self):
     def test_help_env(self):
         out = self.verify_valid_flag('--help-env')
         self.assertIn(b'PYTHONHOME', out)
+        # Env vars in each section should be sorted alphabetically
+        # (ignoring underscores so PYTHON_FOO and PYTHONFOO intermix naturally)
+        sort_key = lambda name: name.replace(b'_', b'').lower()
+        sections = out.split(b'These variables have equivalent')
+        for section in sections:
+            envvars = re.findall(rb'^(PYTHON\w+)', section, re.MULTILINE)
+            self.assertEqual(envvars, sorted(envvars, key=sort_key),
+                             "env vars should be sorted alphabetically")
 
     @support.cpython_only
     def test_help_xoptions(self):
         out = self.verify_valid_flag('--help-xoptions')
         self.assertIn(b'-X dev', out)
+        options = re.findall(rb'^-X (\w+)', out, re.MULTILINE)
+        self.assertEqual(options, sorted(options),
+                         "options should be sorted alphabetically")
 
     @support.cpython_only
     def test_help_all(self):
diff --git a/Lib/test/test_pyexpat.py b/Lib/test/test_pyexpat.py
index 31bcee293b2b69..f8afc16d3cb4cb 100644
--- a/Lib/test/test_pyexpat.py
+++ b/Lib/test/test_pyexpat.py
@@ -701,6 +701,25 @@ def test_trigger_leak(self):
         parser.ElementDeclHandler = lambda _1, _2: None
         self.assertRaises(TypeError, parser.Parse, data, True)
 
+    @support.skip_if_unlimited_stack_size
+    @support.skip_emscripten_stack_overflow()
+    @support.skip_wasi_stack_overflow()
+    def test_deeply_nested_content_model(self):
+        # This should raise a RecursionError and not crash.
+        # See https://github.com/python/cpython/issues/145986.
+        N = 500_000
+        data = (
+            b'<!DOCTYPE root [\n<!ELEMENT root '
+            + b'(a, ' * N + b'a' + b')' * N
+            + b'>\n]>\n<root/>\n'
+        )
+
+        parser = expat.ParserCreate()
+        parser.ElementDeclHandler = lambda _1, _2: None
+        with support.infinite_recursion():
+            with self.assertRaises(RecursionError):
+                parser.Parse(data)
+
 class MalformedInputTest(unittest.TestCase):
     def test1(self):
         xml = b"\0\r\n"
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 8974361c2537d2..a729efee18c3a1 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -858,24 +858,35 @@ def test_subinterp_intern_singleton(self):
                     '''))
                 self.assertTrue(sys._is_interned(s))
 
-    def test_sys_flags(self):
+    def test_sys_flags_indexable_attributes(self):
         self.assertTrue(sys.flags)
-        attrs = ("debug",
+        # We've stopped assigning sequence indices to new sys.flags attributes:
+        # https://github.com/python/cpython/issues/122575#issuecomment-2416497086
+        indexable_attrs = ("debug",
                  "inspect", "interactive", "optimize",
                  "dont_write_bytecode", "no_user_site", "no_site",
                  "ignore_environment", "verbose", "bytes_warning", "quiet",
                  "hash_randomization", "isolated", "dev_mode", "utf8_mode",
-                 "warn_default_encoding", "safe_path", "int_max_str_digits",
-                 "lazy_imports")
-        for attr in attrs:
+                 "warn_default_encoding", "safe_path", "int_max_str_digits")
+        for attr_idx, attr in enumerate(indexable_attrs):
             self.assertHasAttr(sys.flags, attr)
             attr_type = bool if attr in ("dev_mode", "safe_path") else int
             self.assertEqual(type(getattr(sys.flags, attr)), attr_type, attr)
+            attr_value = getattr(sys.flags, attr)
+            self.assertEqual(sys.flags[attr_idx], attr_value,
+                             msg=f"sys.flags .{attr} vs [{attr_idx}]")
         self.assertTrue(repr(sys.flags))
-        self.assertEqual(len(sys.flags), len(attrs))
+        self.assertEqual(len(sys.flags), 18, msg="Do not increase, see GH-122575")
 
         self.assertIn(sys.flags.utf8_mode, {0, 1, 2})
 
+    def test_sys_flags_name_only_attributes(self):
+        # non-tuple sequence fields (name only sys.flags attributes)
+        self.assertIsInstance(sys.flags.gil, int|type(None))
+        self.assertIsInstance(sys.flags.thread_inherit_context, int|type(None))
+        self.assertIsInstance(sys.flags.context_aware_warnings, int|type(None))
+        self.assertIsInstance(sys.flags.lazy_imports, int|type(None))
+
     def assert_raise_on_new_sys_type(self, sys_attr):
         # Users are intentionally prevented from creating new instances of
         # sys.flags, sys.version_info, and sys.getwindowsversion.
@@ -1908,10 +1919,16 @@ def test_pythontypes(self):
         # symtable entry
         # XXX
         # sys.flags
-        # FIXME: The +3 is for the 'gil', 'thread_inherit_context' and
-        # 'context_aware_warnings' flags and will not be necessary once
-        # gh-122575 is fixed
-        check(sys.flags, vsize('') + self.P + self.P * (3 + len(sys.flags)))
+        # FIXME: The non_sequence_fields adjustment is for these flags:
+        # - 'gil'
+        # - 'thread_inherit_context'
+        # - 'context_aware_warnings'
+        # - 'lazy_imports'
+        # Not needing to increment this every time we add a new field
+        # per GH-122575 would be nice...
+        # Q: What is the actual point of this sys.flags C size derived from PyStructSequence_Field array assertion?
+        non_sequence_fields = 4
+        check(sys.flags, vsize('') + self.P + self.P * (non_sequence_fields + len(sys.flags)))
 
     def test_asyncgen_hooks(self):
         old = sys.get_asyncgen_hooks()
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-20-47-34.gh-issue-145990.14BUzw.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-20-47-34.gh-issue-145990.14BUzw.rst
new file mode 100644
index 00000000000000..f66c156b4bc916
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-20-47-34.gh-issue-145990.14BUzw.rst
@@ -0,0 +1 @@
+``python --help-xoptions`` is now sorted by ``-X`` option name.
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-21-45-35.gh-issue-145990.tmXwRB.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-21-45-35.gh-issue-145990.tmXwRB.rst
new file mode 100644
index 00000000000000..21b9a524d005f9
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-15-21-45-35.gh-issue-145990.tmXwRB.rst
@@ -0,0 +1 @@
+``python --help-env`` sections are now sorted by environment variable name.
diff --git a/Misc/NEWS.d/next/Library/2026-03-15-10-17-51.gh-issue-145968.gZexry.rst b/Misc/NEWS.d/next/Library/2026-03-15-10-17-51.gh-issue-145968.gZexry.rst
new file mode 100644
index 00000000000000..9eae1dc400838a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-03-15-10-17-51.gh-issue-145968.gZexry.rst
@@ -0,0 +1,2 @@
+Fix translation in :func:`base64.b64decode` when altchars overlaps with the
+standard ones.
diff --git a/Misc/NEWS.d/next/Security/2026-03-14-17-31-39.gh-issue-145986.ifSSr8.rst b/Misc/NEWS.d/next/Security/2026-03-14-17-31-39.gh-issue-145986.ifSSr8.rst
new file mode 100644
index 00000000000000..79536d1fef543f
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-03-14-17-31-39.gh-issue-145986.ifSSr8.rst
@@ -0,0 +1,4 @@
+:mod:`xml.parsers.expat`: Fixed a crash caused by unbounded C recursion when
+converting deeply nested XML content models with
+:meth:`~xml.parsers.expat.xmlparser.ElementDeclHandler`.
+This addresses :cve:`2026-4224`.
diff --git a/Misc/NEWS.d/next/Tools-Demos/2026-03-15-20-59-29.gh-issue-145976.rEdUI-.rst b/Misc/NEWS.d/next/Tools-Demos/2026-03-15-20-59-29.gh-issue-145976.rEdUI-.rst
new file mode 100644
index 00000000000000..17b0f2d797fa48
--- /dev/null
+++ b/Misc/NEWS.d/next/Tools-Demos/2026-03-15-20-59-29.gh-issue-145976.rEdUI-.rst
@@ -0,0 +1,2 @@
+Remove :file:`Misc/indent.pro`, a configuration file for GNU
+:manpage:`indent(1)`.
diff --git a/Misc/README b/Misc/README
index 038f842e0bc02e..1993c58ad8c960 100644
--- a/Misc/README
+++ b/Misc/README
@@ -9,8 +9,7 @@ Files found here
 
 ACKS                    Acknowledgements
 HISTORY                 News from previous releases -- oldest last
-indent.pro              GNU indent profile approximating my C style
-NEWS                    News for this release (for some meaning of "this")
+NEWS.d/                 News files for this release (for some meaning of "this")
 python-config.in        Python script template for python-config
 python.man              UNIX man page for the python interpreter
 python.pc.in            Package configuration info template for pkg-config
diff --git a/Misc/indent.pro b/Misc/indent.pro
deleted file mode 100644
index 02cceb62021453..00000000000000
--- a/Misc/indent.pro
+++ /dev/null
@@ -1,24 +0,0 @@
---blank-lines-after-declarations
---blank-lines-after-procedures
---braces-after-func-def-line
---braces-on-if-line
---braces-on-struct-decl-line
---break-after-boolean-operator
---comment-indentation25
---comment-line-length79
---continue-at-parentheses
---dont-cuddle-do-while
---dont-cuddle-else
---indent-level4
---line-length79
---no-space-after-casts
---no-space-after-function-call-names
---no-space-after-parentheses
---no-tabs
---procnames-start-lines
---space-after-for
---space-after-if
---space-after-while
---swallow-optional-blank-lines
--T PyCFunction
--T PyObject
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index e9255038eee5b5..cadc6706243524 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -3,6 +3,7 @@
 #endif
 
 #include "Python.h"
+#include "pycore_ceval.h"         // _Py_EnterRecursiveCall()
 #include "pycore_import.h"        // _PyImport_SetModule()
 #include "pycore_pyhash.h"        // _Py_HashSecret
 #include "pycore_traceback.h"     // _PyTraceback_Add()
@@ -607,6 +608,10 @@ static PyObject *
 conv_content_model(XML_Content * const model,
                    PyObject *(*conv_string)(void *))
 {
+    if (_Py_EnterRecursiveCall(" in conv_content_model")) {
+        return NULL;
+    }
+
     PyObject *result = NULL;
     PyObject *children = PyTuple_New(model->numchildren);
     int i;
@@ -618,7 +623,7 @@ conv_content_model(XML_Content * const model,
                                                  conv_string);
             if (child == NULL) {
                 Py_XDECREF(children);
-                return NULL;
+                goto done;
             }
             PyTuple_SET_ITEM(children, i, child);
         }
@@ -626,6 +631,8 @@ conv_content_model(XML_Content * const model,
                                model->type, model->quant,
                                conv_string, model->name, children);
     }
+done:
+    _Py_LeaveRecursiveCall();
     return result;
 }
 
diff --git a/Python/initconfig.c b/Python/initconfig.c
index 57629ff8c57380..caf42f5247c2f2 100644
--- a/Python/initconfig.c
+++ b/Python/initconfig.c
@@ -304,9 +304,15 @@ arg ...: arguments passed to program in sys.argv[1:]\n\
 
 static const char usage_xoptions[] = "\
 The following implementation-specific options are available:\n\
+-X context_aware_warnings=[0|1]: if true (1) then the warnings module will\n\
+         use a context variables; if false (0) then the warnings module will\n\
+         use module globals, which is not concurrent-safe; set to true for\n\
+         free-threaded builds and false otherwise; also\n\
+         PYTHON_CONTEXT_AWARE_WARNINGS\n\
 -X cpu_count=N: override the return value of os.cpu_count();\n\
          -X cpu_count=default cancels overriding; also PYTHON_CPU_COUNT\n\
 -X dev : enable Python Development Mode; also PYTHONDEVMODE\n\
+-X disable-remote-debug: disable remote debugging; also PYTHON_DISABLE_REMOTE_DEBUG\n\
 -X faulthandler: dump the Python traceback on fatal errors;\n\
          also PYTHONFAULTHANDLER\n\
 -X frozen_modules=[on|off]: whether to use frozen modules; the default is \"on\"\n\
@@ -319,16 +325,18 @@ The following implementation-specific options are available:\n\
 "\
 -X importtime[=2]: show how long each import takes; use -X importtime=2 to\n\
          log imports of already-loaded modules; also PYTHONPROFILEIMPORTTIME\n\
--X lazy_imports=[all|none|normal]: control global lazy imports;\n\
-         default is normal; also PYTHON_LAZY_IMPORTS\n\
 -X int_max_str_digits=N: limit the size of int<->str conversions;\n\
          0 disables the limit; also PYTHONINTMAXSTRDIGITS\n\
+-X lazy_imports=[all|none|normal]: control global lazy imports;\n\
+         default is normal; also PYTHON_LAZY_IMPORTS\n\
 -X no_debug_ranges: don't include extra location information in code objects;\n\
          also PYTHONNODEBUGRANGES\n\
+-X pathconfig_warnings=[0|1]: if true (1) then path configuration is allowed\n\
+         to log warnings into stderr; if false (0) suppress these warnings;\n\
+         set to true by default; also PYTHON_PATHCONFIG_WARNINGS\n\
 -X perf: support the Linux \"perf\" profiler; also PYTHONPERFSUPPORT=1\n\
 -X perf_jit: support the Linux \"perf\" profiler with DWARF support;\n\
          also PYTHON_PERF_JIT_SUPPORT=1\n\
--X disable-remote-debug: disable remote debugging; also PYTHON_DISABLE_REMOTE_DEBUG\n\
 "
 #ifdef Py_DEBUG
 "-X presite=MOD: import this module before site; also PYTHON_PRESITE\n"
@@ -343,24 +351,17 @@ The following implementation-specific options are available:\n\
 "\
 -X showrefcount: output the total reference count and number of used\n\
          memory blocks when the program finishes or after each statement in\n\
-         the interactive interpreter; only works on debug builds\n"
+         the interactive interpreter; only works on debug builds\n\
+-X thread_inherit_context=[0|1]: enable (1) or disable (0) threads inheriting\n\
+         context vars by default; enabled by default in the free-threaded\n\
+         build and disabled otherwise; also PYTHON_THREAD_INHERIT_CONTEXT\n\
+"
 #ifdef Py_GIL_DISABLED
 "-X tlbc=[0|1]: enable (1) or disable (0) thread-local bytecode. Also\n\
          PYTHON_TLBC\n"
 #endif
 "\
--X thread_inherit_context=[0|1]: enable (1) or disable (0) threads inheriting\n\
-         context vars by default; enabled by default in the free-threaded\n\
-         build and disabled otherwise; also PYTHON_THREAD_INHERIT_CONTEXT\n\
--X context_aware_warnings=[0|1]: if true (1) then the warnings module will\n\
-         use a context variables; if false (0) then the warnings module will\n\
-         use module globals, which is not concurrent-safe; set to true for\n\
-         free-threaded builds and false otherwise; also\n\
-         PYTHON_CONTEXT_AWARE_WARNINGS\n\
--X pathconfig_warnings=[0|1]: if true (1) then path configuration is allowed\n\
-         to log warnings into stderr; if false (0) suppress these warnings;\n\
-         set to true by default; also PYTHON_PATHCONFIG_WARNINGS\n\
--X tracemalloc[=N]: trace Python memory allocations; N sets a traceback limit\n \
+-X tracemalloc[=N]: trace Python memory allocations; N sets a traceback limit\n\
          of N frames (default: 1); also PYTHONTRACEMALLOC=N\n\
 -X utf8[=0|1]: enable (1) or disable (0) UTF-8 mode; also PYTHONUTF8\n\
 -X warn_default_encoding: enable opt-in EncodingWarning for 'encoding=None';\n\
@@ -370,34 +371,19 @@ The following implementation-specific options are available:\n\
 /* Envvars that don't have equivalent command-line options are listed first */
 static const char usage_envvars[] =
 "Environment variables that change behavior:\n"
-"PYTHONSTARTUP   : file executed on interactive startup (no default)\n"
-"PYTHONPATH      : '%lc'-separated list of directories prefixed to the\n"
-"                  default module search path.  The result is sys.path.\n"
-"PYTHONHOME      : alternate <prefix> directory (or <prefix>%lc<exec_prefix>).\n"
-"                  The default module search path uses %s.\n"
-"PYTHONPLATLIBDIR: override sys.platlibdir\n"
+"PYTHONASYNCIODEBUG: enable asyncio debug mode\n"
+"PYTHON_BASIC_REPL: use the traditional parser-based REPL\n"
+"PYTHONBREAKPOINT: if this variable is set to 0, it disables the default\n"
+"                  debugger.  It can be set to the callable of your debugger of\n"
+"                  choice.\n"
 "PYTHONCASEOK    : ignore case in 'import' statements (Windows)\n"
-"PYTHONIOENCODING: encoding[:errors] used for stdin/stdout/stderr\n"
-"PYTHONHASHSEED  : if this variable is set to 'random', a random value is used\n"
-"                  to seed the hashes of str and bytes objects.  It can also be\n"
-"                  set to an integer in the range [0,4294967295] to get hash\n"
-"                  values with a predictable seed.\n"
-"PYTHONMALLOC    : set the Python memory allocators and/or install debug hooks\n"
-"                  on Python memory allocators.  Use PYTHONMALLOC=debug to\n"
-"                  install debug hooks.\n"
-"PYTHONMALLOCSTATS: print memory allocator statistics\n"
 "PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale\n"
 "                  coercion behavior.  Use PYTHONCOERCECLOCALE=warn to request\n"
 "                  display of locale coercion and locale compatibility warnings\n"
 "                  on stderr.\n"
-"PYTHONBREAKPOINT: if this variable is set to 0, it disables the default\n"
-"                  debugger.  It can be set to the callable of your debugger of\n"
-"                  choice.\n"
 "PYTHON_COLORS   : if this variable is set to 1, the interpreter will colorize\n"
 "                  various kinds of output.  Setting it to 0 deactivates\n"
 "                  this behavior.\n"
-"PYTHON_HISTORY  : the location of a .python_history file.\n"
-"PYTHONASYNCIODEBUG: enable asyncio debug mode\n"
 #ifdef Py_TRACE_REFS
 "PYTHONDUMPREFS  : dump objects and reference counts still alive after shutdown\n"
 "PYTHONDUMPREFSFILE: dump objects and reference counts to the specified file\n"
@@ -405,14 +391,31 @@ static const char usage_envvars[] =
 #ifdef __APPLE__
 "PYTHONEXECUTABLE: set sys.argv[0] to this value (macOS only)\n"
 #endif
+"PYTHONHASHSEED  : if this variable is set to 'random', a random value is used\n"
+"                  to seed the hashes of str and bytes objects.  It can also be\n"
+"                  set to an integer in the range [0,4294967295] to get hash\n"
+"                  values with a predictable seed.\n"
+"PYTHON_HISTORY  : the location of a .python_history file.\n"
+"PYTHONHOME      : alternate <prefix> directory (or <prefix>%lc<exec_prefix>).\n"
+"                  The default module search path uses %s.\n"
+"PYTHONIOENCODING: encoding[:errors] used for stdin/stdout/stderr\n"
 #ifdef MS_WINDOWS
 "PYTHONLEGACYWINDOWSFSENCODING: use legacy \"mbcs\" encoding for file system\n"
 "PYTHONLEGACYWINDOWSSTDIO: use legacy Windows stdio\n"
 #endif
+"PYTHONMALLOC    : set the Python memory allocators and/or install debug hooks\n"
+"                  on Python memory allocators.  Use PYTHONMALLOC=debug to\n"
+"                  install debug hooks.\n"
+"PYTHONMALLOCSTATS: print memory allocator statistics\n"
+"PYTHONPATH      : '%lc'-separated list of directories prefixed to the\n"
+"                  default module search path.  The result is sys.path.\n"
+"PYTHONPLATLIBDIR: override sys.platlibdir\n"
+"PYTHONSTARTUP   : file executed on interactive startup (no default)\n"
 "PYTHONUSERBASE  : defines the user base directory (site.USER_BASE)\n"
-"PYTHON_BASIC_REPL: use the traditional parser-based REPL\n"
 "\n"
 "These variables have equivalent command-line options (see --help for details):\n"
+"PYTHON_CONTEXT_AWARE_WARNINGS: if true (1), enable thread-safe warnings\n"
+"                  module behaviour (-X context_aware_warnings)\n"
 "PYTHON_CPU_COUNT: override the return value of os.cpu_count() (-X cpu_count)\n"
 "PYTHONDEBUG     : enable parser debug mode (-d)\n"
 "PYTHONDEVMODE   : enable Python Development Mode (-X dev)\n"
@@ -427,31 +430,29 @@ static const char usage_envvars[] =
 "PYTHONINSPECT   : inspect interactively after running script (-i)\n"
 "PYTHONINTMAXSTRDIGITS: limit the size of int<->str conversions;\n"
 "                  0 disables the limit (-X int_max_str_digits=N)\n"
+"PYTHON_LAZY_IMPORTS: control global lazy imports (-X lazy_imports)\n"
 "PYTHONNODEBUGRANGES: don't include extra location information in code objects\n"
 "                  (-X no_debug_ranges)\n"
 "PYTHONNOUSERSITE: disable user site directory (-s)\n"
 "PYTHONOPTIMIZE  : enable level 1 optimizations (-O)\n"
-"PYTHONPERFSUPPORT: support the Linux \"perf\" profiler (-X perf)\n"
 "PYTHON_PERF_JIT_SUPPORT: enable Linux \"perf\" profiler support with JIT\n"
 "                  (-X perf_jit)\n"
+"PYTHONPERFSUPPORT: support the Linux \"perf\" profiler (-X perf)\n"
 #ifdef Py_DEBUG
 "PYTHON_PRESITE: import this module before site (-X presite)\n"
 #endif
 "PYTHONPROFILEIMPORTTIME: show how long each import takes (-X importtime)\n"
-"PYTHON_LAZY_IMPORTS: control global lazy imports (-X lazy_imports)\n"
 "PYTHONPYCACHEPREFIX: root directory for bytecode cache (pyc) files\n"
 "                  (-X pycache_prefix)\n"
 "PYTHONSAFEPATH  : don't prepend a potentially unsafe path to sys.path.\n"
 #ifdef Py_STATS
 "PYTHONSTATS     : turns on statistics gathering (-X pystats)\n"
 #endif
+"PYTHON_THREAD_INHERIT_CONTEXT: if true (1), threads inherit context vars\n"
+"                  (-X thread_inherit_context)\n"
 #ifdef Py_GIL_DISABLED
 "PYTHON_TLBC     : when set to 0, disables thread-local bytecode (-X tlbc)\n"
 #endif
-"PYTHON_THREAD_INHERIT_CONTEXT: if true (1), threads inherit context vars\n"
-"                   (-X thread_inherit_context)\n"
-"PYTHON_CONTEXT_AWARE_WARNINGS: if true (1), enable thread-safe warnings module\n"
-"                   behaviour (-X context_aware_warnings)\n"
 "PYTHONTRACEMALLOC: trace Python memory allocations (-X tracemalloc)\n"
 "PYTHONUNBUFFERED: disable stdout/stderr buffering (-u)\n"
 "PYTHONUTF8      : control the UTF-8 mode (-X utf8)\n"
@@ -2946,7 +2947,7 @@ config_usage(int error, const wchar_t* program)
 static void
 config_envvars_usage(void)
 {
-    printf(usage_envvars, (wint_t)DELIM, (wint_t)DELIM, PYTHONHOMEHELP);
+    printf(usage_envvars, (wint_t)DELIM, PYTHONHOMEHELP, (wint_t)DELIM);
 }
 
 static void
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 893a116565e37e..646b8a1c3c3a84 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -3495,11 +3495,12 @@ static PyStructSequence_Field flags_fields[] = {
     {"dev_mode",                "-X dev"},
     {"utf8_mode",               "-X utf8"},
     {"warn_default_encoding",   "-X warn_default_encoding"},
-    {"safe_path", "-P"},
+    {"safe_path",               "-P"},
     {"int_max_str_digits",      "-X int_max_str_digits"},
+    // Fields below are only usable by sys.flags attribute name, not index:
     {"gil",                     "-X gil"},
     {"thread_inherit_context",  "-X thread_inherit_context"},
-    {"context_aware_warnings",    "-X context_aware_warnings"},
+    {"context_aware_warnings",  "-X context_aware_warnings"},
     {"lazy_imports",            "-X lazy_imports"},
     {0}
 };
@@ -3510,7 +3511,9 @@ static PyStructSequence_Desc flags_desc = {
     "sys.flags",        /* name */
     flags__doc__,       /* doc */
     flags_fields,       /* fields */
-    19
+    18  /* NB - do not increase beyond 3.13's value of 18. */
+    // New sys.flags fields should NOT be tuple addressable per
+    // https://github.com/python/cpython/issues/122575#issuecomment-2416497086
 };
 
 static void