diff --git a/Doc/library/__main__.rst b/Doc/library/__main__.rst
index 647ff9da04d10d..4407ba2f7714dd 100644
--- a/Doc/library/__main__.rst
+++ b/Doc/library/__main__.rst
@@ -292,10 +292,7 @@ Here is an example module that consumes the ``__main__`` namespace::
         if not did_user_define_their_name():
             raise ValueError('Define the variable `my_name`!')
 
-        if '__file__' in dir(__main__):
-            print(__main__.my_name, "found in file", __main__.__file__)
-        else:
-            print(__main__.my_name)
+        print(__main__.my_name)
 
 Example usage of this module could be as follows::
 
@@ -330,7 +327,7 @@ status code 0, indicating success:
 .. code-block:: shell-session
 
    $ python start.py
-   Dinsdale found in file /path/to/start.py
+   Dinsdale
 
 Note that importing ``__main__`` doesn't cause any issues with unintentionally
 running top-level code meant for script use which is put in the
@@ -361,8 +358,5 @@ defined in the REPL becomes part of the ``__main__`` scope::
     >>> namely.print_user_name()
     Jabberwocky
 
-Note that in this case the ``__main__`` scope doesn't contain a ``__file__``
-attribute as it's interactive.
-
 The ``__main__`` scope is used in the implementation of :mod:`pdb` and
 :mod:`rlcompleter`.
diff --git a/Doc/reference/compound_stmts.rst b/Doc/reference/compound_stmts.rst
index 1b1e9f479cbe08..71cc0c83de567e 100644
--- a/Doc/reference/compound_stmts.rst
+++ b/Doc/reference/compound_stmts.rst
@@ -1217,8 +1217,10 @@ A function definition defines a user-defined function object (see section
                  :   | `parameter_list_no_posonly`
    parameter_list_no_posonly: `defparameter` ("," `defparameter`)* ["," [`parameter_list_starargs`]]
                             : | `parameter_list_starargs`
-   parameter_list_starargs: "*" [`star_parameter`] ("," `defparameter`)* ["," ["**" `parameter` [","]]]
-                          : | "**" `parameter` [","]
+   parameter_list_starargs: "*" [`star_parameter`] ("," `defparameter`)* ["," [`parameter_star_kwargs`]]
+                          : "*" ("," `defparameter`)+ ["," [`parameter_star_kwargs`]]
+                          : | `parameter_star_kwargs`
+   parameter_star_kwargs: "**" `parameter` [","]
    parameter: `identifier` [":" `expression`]
    star_parameter: `identifier` [":" ["*"] `expression`]
    defparameter: `parameter` ["=" `expression`]
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 7db2f4820f346a..2a59cf3f62d4c5 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -1195,7 +1195,7 @@ conflict.
 
 .. envvar:: PYTHON_BASIC_REPL
 
-   If this variable is set to ``1``, the interpreter will not attempt to
+   If this variable is set to any value, the interpreter will not attempt to
    load the Python-based :term:`REPL` that requires :mod:`curses` and
    :mod:`readline`, and will instead use the traditional parser-based
    :term:`REPL`.
diff --git a/Lib/_pyrepl/commands.py b/Lib/_pyrepl/commands.py
index c3fce91013b001..503ca1da329eaa 100644
--- a/Lib/_pyrepl/commands.py
+++ b/Lib/_pyrepl/commands.py
@@ -282,7 +282,7 @@ def do(self) -> None:
             x, y = r.pos2xy()
             new_y = y + 1
 
-            if new_y > r.max_row():
+            if r.eol() == len(b):
                 if r.historyi < len(r.history):
                     r.select_item(r.historyi + 1)
                     r.pos = r.eol(0)
@@ -309,7 +309,7 @@ def do(self) -> None:
 class left(MotionCommand):
     def do(self) -> None:
         r = self.reader
-        for i in range(r.get_arg()):
+        for _ in range(r.get_arg()):
             p = r.pos - 1
             if p >= 0:
                 r.pos = p
@@ -321,7 +321,7 @@ class right(MotionCommand):
     def do(self) -> None:
         r = self.reader
         b = r.buffer
-        for i in range(r.get_arg()):
+        for _ in range(r.get_arg()):
             p = r.pos + 1
             if p <= len(b):
                 r.pos = p
@@ -459,9 +459,15 @@ def do(self) -> None:
         from site import gethistoryfile  # type: ignore[attr-defined]
 
         history = os.linesep.join(self.reader.history[:])
-        with self.reader.suspend():
-            pager = get_pager()
-            pager(history, gethistoryfile())
+        self.reader.console.restore()
+        pager = get_pager()
+        pager(history, gethistoryfile())
+        self.reader.console.prepare()
+
+        # We need to copy over the state so that it's consistent between
+        # console and reader, and console does not overwrite/append stuff
+        self.reader.console.screen = self.reader.screen.copy()
+        self.reader.console.posxy = self.reader.cxy
 
 
 class paste_mode(Command):
diff --git a/Lib/_pyrepl/completing_reader.py b/Lib/_pyrepl/completing_reader.py
index e856bb9807c7f6..1cd4b6367ca8b1 100644
--- a/Lib/_pyrepl/completing_reader.py
+++ b/Lib/_pyrepl/completing_reader.py
@@ -260,10 +260,15 @@ def after_command(self, cmd: Command) -> None:
     def calc_screen(self) -> list[str]:
         screen = super().calc_screen()
         if self.cmpltn_menu_visible:
-            ly = self.lxy[1]
+            # We display the completions menu below the current prompt
+            ly = self.lxy[1] + 1
             screen[ly:ly] = self.cmpltn_menu
-            self.screeninfo[ly:ly] = [(0, [])]*len(self.cmpltn_menu)
-            self.cxy = self.cxy[0], self.cxy[1] + len(self.cmpltn_menu)
+            # If we're not in the middle of multiline edit, don't append to screeninfo
+            # since that screws up the position calculation in pos2xy function.
+            # This is a hack to prevent the cursor jumping
+            # into the completions menu when pressing left or down arrow.
+            if self.pos != len(self.buffer):
+                self.screeninfo[ly:ly] = [(0, [])]*len(self.cmpltn_menu)
         return screen
 
     def finish(self) -> None:
diff --git a/Lib/_pyrepl/console.py b/Lib/_pyrepl/console.py
index 03266c4dfc2dd8..0d78890b4f45d5 100644
--- a/Lib/_pyrepl/console.py
+++ b/Lib/_pyrepl/console.py
@@ -45,6 +45,7 @@ class Event:
 
 @dataclass
 class Console(ABC):
+    posxy: tuple[int, int]
     screen: list[str] = field(default_factory=list)
     height: int = 25
     width: int = 80
diff --git a/Lib/_pyrepl/historical_reader.py b/Lib/_pyrepl/historical_reader.py
index 5d416f336ad5d2..c4b95fa2e81ee6 100644
--- a/Lib/_pyrepl/historical_reader.py
+++ b/Lib/_pyrepl/historical_reader.py
@@ -290,13 +290,17 @@ def get_item(self, i: int) -> str:
 
     @contextmanager
     def suspend(self) -> SimpleContextManager:
-        with super().suspend():
-            try:
-                old_history = self.history[:]
-                del self.history[:]
-                yield
-            finally:
-                self.history[:] = old_history
+        with super().suspend(), self.suspend_history():
+            yield
+
+    @contextmanager
+    def suspend_history(self) -> SimpleContextManager:
+        try:
+            old_history = self.history[:]
+            del self.history[:]
+            yield
+        finally:
+            self.history[:] = old_history
 
     def prepare(self) -> None:
         super().prepare()
diff --git a/Lib/_pyrepl/simple_interact.py b/Lib/_pyrepl/simple_interact.py
index a5033496712a73..a065174ad42fb6 100644
--- a/Lib/_pyrepl/simple_interact.py
+++ b/Lib/_pyrepl/simple_interact.py
@@ -77,7 +77,7 @@ def _clear_screen():
     "exit": _sitebuiltins.Quitter('exit', ''),
     "quit": _sitebuiltins.Quitter('quit' ,''),
     "copyright": _sitebuiltins._Printer('copyright', sys.copyright),
-    "help": "help",
+    "help": _sitebuiltins._Helper(),
     "clear": _clear_screen,
     "\x1a": _sitebuiltins.Quitter('\x1a', ''),
 }
@@ -124,18 +124,10 @@ def maybe_run_command(statement: str) -> bool:
         reader.history.pop()  # skip internal commands in history
         command = REPL_COMMANDS[statement]
         if callable(command):
-            command()
+            # Make sure that history does not change because of commands
+            with reader.suspend_history():
+                command()
             return True
-
-        if isinstance(command, str):
-            # Internal readline commands require a prepared reader like
-            # inside multiline_input.
-            reader.prepare()
-            reader.refresh()
-            reader.do_cmd((command, [statement]))
-            reader.restore()
-            return True
-
         return False
 
     while True:
diff --git a/Lib/_pyrepl/unix_console.py b/Lib/_pyrepl/unix_console.py
index 63e8fc24dd7625..add31d52f78651 100644
--- a/Lib/_pyrepl/unix_console.py
+++ b/Lib/_pyrepl/unix_console.py
@@ -240,7 +240,7 @@ def refresh(self, screen, c_xy):
                 self.__hide_cursor()
                 self.__move(0, len(self.screen) - 1)
                 self.__write("\n")
-                self.__posxy = 0, len(self.screen)
+                self.posxy = 0, len(self.screen)
                 self.screen.append("")
         else:
             while len(self.screen) < len(screen):
@@ -250,7 +250,7 @@ def refresh(self, screen, c_xy):
             self.__gone_tall = 1
             self.__move = self.__move_tall
 
-        px, py = self.__posxy
+        px, py = self.posxy
         old_offset = offset = self.__offset
         height = self.height
 
@@ -271,7 +271,7 @@ def refresh(self, screen, c_xy):
         if old_offset > offset and self._ri:
             self.__hide_cursor()
             self.__write_code(self._cup, 0, 0)
-            self.__posxy = 0, old_offset
+            self.posxy = 0, old_offset
             for i in range(old_offset - offset):
                 self.__write_code(self._ri)
                 oldscr.pop(-1)
@@ -279,7 +279,7 @@ def refresh(self, screen, c_xy):
         elif old_offset < offset and self._ind:
             self.__hide_cursor()
             self.__write_code(self._cup, self.height - 1, 0)
-            self.__posxy = 0, old_offset + self.height - 1
+            self.posxy = 0, old_offset + self.height - 1
             for i in range(offset - old_offset):
                 self.__write_code(self._ind)
                 oldscr.pop(0)
@@ -299,7 +299,7 @@ def refresh(self, screen, c_xy):
         while y < len(oldscr):
             self.__hide_cursor()
             self.__move(0, y)
-            self.__posxy = 0, y
+            self.posxy = 0, y
             self.__write_code(self._el)
             y += 1
 
@@ -321,7 +321,7 @@ def move_cursor(self, x, y):
             self.event_queue.insert(Event("scroll", None))
         else:
             self.__move(x, y)
-            self.__posxy = x, y
+            self.posxy = x, y
             self.flushoutput()
 
     def prepare(self):
@@ -350,7 +350,7 @@ def prepare(self):
 
         self.__buffer = []
 
-        self.__posxy = 0, 0
+        self.posxy = 0, 0
         self.__gone_tall = 0
         self.__move = self.__move_short
         self.__offset = 0
@@ -559,7 +559,7 @@ def clear(self):
         self.__write_code(self._clear)
         self.__gone_tall = 1
         self.__move = self.__move_tall
-        self.__posxy = 0, 0
+        self.posxy = 0, 0
         self.screen = []
 
     @property
@@ -644,8 +644,8 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
         # if we need to insert a single character right after the first detected change
         if oldline[x_pos:] == newline[x_pos + 1 :] and self.ich1:
             if (
-                y == self.__posxy[1]
-                and x_coord > self.__posxy[0]
+                y == self.posxy[1]
+                and x_coord > self.posxy[0]
                 and oldline[px_pos:x_pos] == newline[px_pos + 1 : x_pos + 1]
             ):
                 x_pos = px_pos
@@ -654,7 +654,7 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
             self.__move(x_coord, y)
             self.__write_code(self.ich1)
             self.__write(newline[x_pos])
-            self.__posxy = x_coord + character_width, y
+            self.posxy = x_coord + character_width, y
 
         # if it's a single character change in the middle of the line
         elif (
@@ -665,7 +665,7 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
             character_width = wlen(newline[x_pos])
             self.__move(x_coord, y)
             self.__write(newline[x_pos])
-            self.__posxy = x_coord + character_width, y
+            self.posxy = x_coord + character_width, y
 
         # if this is the last character to fit in the line and we edit in the middle of the line
         elif (
@@ -677,14 +677,14 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
         ):
             self.__hide_cursor()
             self.__move(self.width - 2, y)
-            self.__posxy = self.width - 2, y
+            self.posxy = self.width - 2, y
             self.__write_code(self.dch1)
 
             character_width = wlen(newline[x_pos])
             self.__move(x_coord, y)
             self.__write_code(self.ich1)
             self.__write(newline[x_pos])
-            self.__posxy = character_width + 1, y
+            self.posxy = character_width + 1, y
 
         else:
             self.__hide_cursor()
@@ -692,7 +692,7 @@ def __write_changed_line(self, y, oldline, newline, px_coord):
             if wlen(oldline) > wlen(newline):
                 self.__write_code(self._el)
             self.__write(newline[x_pos:])
-            self.__posxy = wlen(newline), y
+            self.posxy = wlen(newline), y
 
         if "\x1b" in newline:
             # ANSI escape characters are present, so we can't assume
@@ -711,32 +711,36 @@ def __maybe_write_code(self, fmt, *args):
             self.__write_code(fmt, *args)
 
     def __move_y_cuu1_cud1(self, y):
-        dy = y - self.__posxy[1]
+        assert self._cud1 is not None
+        assert self._cuu1 is not None
+        dy = y - self.posxy[1]
         if dy > 0:
             self.__write_code(dy * self._cud1)
         elif dy < 0:
             self.__write_code((-dy) * self._cuu1)
 
     def __move_y_cuu_cud(self, y):
-        dy = y - self.__posxy[1]
+        dy = y - self.posxy[1]
         if dy > 0:
             self.__write_code(self._cud, dy)
         elif dy < 0:
             self.__write_code(self._cuu, -dy)
 
     def __move_x_hpa(self, x: int) -> None:
-        if x != self.__posxy[0]:
+        if x != self.posxy[0]:
             self.__write_code(self._hpa, x)
 
     def __move_x_cub1_cuf1(self, x: int) -> None:
-        dx = x - self.__posxy[0]
+        assert self._cuf1 is not None
+        assert self._cub1 is not None
+        dx = x - self.posxy[0]
         if dx > 0:
             self.__write_code(self._cuf1 * dx)
         elif dx < 0:
             self.__write_code(self._cub1 * (-dx))
 
     def __move_x_cub_cuf(self, x: int) -> None:
-        dx = x - self.__posxy[0]
+        dx = x - self.posxy[0]
         if dx > 0:
             self.__write_code(self._cuf, dx)
         elif dx < 0:
@@ -766,12 +770,12 @@ def __show_cursor(self):
 
     def repaint(self):
         if not self.__gone_tall:
-            self.__posxy = 0, self.__posxy[1]
+            self.posxy = 0, self.posxy[1]
             self.__write("\r")
             ns = len(self.screen) * ["\000" * self.width]
             self.screen = ns
         else:
-            self.__posxy = 0, self.__offset
+            self.posxy = 0, self.__offset
             self.__move(0, self.__offset)
             ns = self.height * ["\000" * self.width]
             self.screen = ns
diff --git a/Lib/_pyrepl/utils.py b/Lib/_pyrepl/utils.py
index 0f36083b6ffa92..4651717bd7e121 100644
--- a/Lib/_pyrepl/utils.py
+++ b/Lib/_pyrepl/utils.py
@@ -16,7 +16,7 @@ def str_width(c: str) -> int:
 
 
 def wlen(s: str) -> int:
-    if len(s) == 1:
+    if len(s) == 1 and s != '\x1a':
         return str_width(s)
     length = sum(str_width(i) for i in s)
     # remove lengths of any escape sequences
diff --git a/Lib/_pyrepl/windows_console.py b/Lib/_pyrepl/windows_console.py
index e738fd09c65758..e1ecd9845aefb4 100644
--- a/Lib/_pyrepl/windows_console.py
+++ b/Lib/_pyrepl/windows_console.py
@@ -152,10 +152,10 @@ def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
             self._hide_cursor()
             self._move_relative(0, len(self.screen) - 1)
             self.__write("\n")
-            self.__posxy = 0, len(self.screen)
+            self.posxy = 0, len(self.screen)
             self.screen.append("")
 
-        px, py = self.__posxy
+        px, py = self.posxy
         old_offset = offset = self.__offset
         height = self.height
 
@@ -171,7 +171,7 @@ def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
             # portion of the window.  We need to scroll the visible portion and the
             # entire history
             self._scroll(scroll_lines, self._getscrollbacksize())
-            self.__posxy = self.__posxy[0], self.__posxy[1] + scroll_lines
+            self.posxy = self.posxy[0], self.posxy[1] + scroll_lines
             self.__offset += scroll_lines
 
             for i in range(scroll_lines):
@@ -197,7 +197,7 @@ def refresh(self, screen: list[str], c_xy: tuple[int, int]) -> None:
         y = len(newscr)
         while y < len(oldscr):
             self._move_relative(0, y)
-            self.__posxy = 0, y
+            self.posxy = 0, y
             self._erase_to_end()
             y += 1
 
@@ -254,11 +254,11 @@ def __write_changed_line(
         if wlen(newline) == self.width:
             # If we wrapped we want to start at the next line
             self._move_relative(0, y + 1)
-            self.__posxy = 0, y + 1
+            self.posxy = 0, y + 1
         else:
-            self.__posxy = wlen(newline), y
+            self.posxy = wlen(newline), y
 
-            if "\x1b" in newline or y != self.__posxy[1] or '\x1a' in newline:
+            if "\x1b" in newline or y != self.posxy[1] or '\x1a' in newline:
                 # ANSI escape characters are present, so we can't assume
                 # anything about the position of the cursor.  Moving the cursor
                 # to the left margin should work to get to a known position.
@@ -320,7 +320,7 @@ def prepare(self) -> None:
         self.screen = []
         self.height, self.width = self.getheightwidth()
 
-        self.__posxy = 0, 0
+        self.posxy = 0, 0
         self.__gone_tall = 0
         self.__offset = 0
 
@@ -328,9 +328,9 @@ def restore(self) -> None:
         pass
 
     def _move_relative(self, x: int, y: int) -> None:
-        """Moves relative to the current __posxy"""
-        dx = x - self.__posxy[0]
-        dy = y - self.__posxy[1]
+        """Moves relative to the current posxy"""
+        dx = x - self.posxy[0]
+        dy = y - self.posxy[1]
         if dx < 0:
             self.__write(MOVE_LEFT.format(-dx))
         elif dx > 0:
@@ -349,7 +349,7 @@ def move_cursor(self, x: int, y: int) -> None:
             self.event_queue.insert(0, Event("scroll", ""))
         else:
             self._move_relative(x, y)
-            self.__posxy = x, y
+            self.posxy = x, y
 
     def set_cursor_vis(self, visible: bool) -> None:
         if visible:
@@ -455,7 +455,7 @@ def beep(self) -> None:
     def clear(self) -> None:
         """Wipe the screen"""
         self.__write(CLEAR)
-        self.__posxy = 0, 0
+        self.posxy = 0, 0
         self.screen = [""]
 
     def finish(self) -> None:
diff --git a/Lib/test/test_pyrepl/test_pyrepl.py b/Lib/test/test_pyrepl/test_pyrepl.py
index bbe19612437a1d..00dc990d946a9b 100644
--- a/Lib/test/test_pyrepl/test_pyrepl.py
+++ b/Lib/test/test_pyrepl/test_pyrepl.py
@@ -850,7 +850,7 @@ def test_global_namespace_completion(self):
         output = multiline_input(reader, namespace)
         self.assertEqual(output, "python")
 
-    def test_updown_arrow_with_completion_menu(self):
+    def test_up_down_arrow_with_completion_menu(self):
         """Up arrow in the middle of unfinished tab completion when the menu is displayed
         should work and trigger going back in history. Down arrow should subsequently
         get us back to the incomplete command."""
@@ -860,6 +860,7 @@ def test_updown_arrow_with_completion_menu(self):
         events = itertools.chain(
             code_to_events(code),
             [
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
                 Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
                 Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
             ],
@@ -1343,3 +1344,16 @@ def test_readline_history_file(self):
     def test_keyboard_interrupt_after_isearch(self):
         output, exit_code = self.run_repl(["\x12", "\x03", "exit"])
         self.assertEqual(exit_code, 0)
+
+    def test_prompt_after_help(self):
+        output, exit_code = self.run_repl(["help", "q", "exit"])
+
+        # Regex pattern to remove ANSI escape sequences
+        ansi_escape = re.compile(r"(\x1B(=|>|(\[)[0-?]*[ -\/]*[@-~]))")
+        cleaned_output = ansi_escape.sub("", output)
+        self.assertEqual(exit_code, 0)
+
+        # Ensure that we don't see multiple prompts after exiting `help`
+        # Extra stuff (newline and `exit` rewrites) are necessary
+        # because of how run_repl works.
+        self.assertNotIn(">>> \n>>> >>>", cleaned_output)
diff --git a/Lib/test/test_pyrepl/test_reader.py b/Lib/test/test_pyrepl/test_reader.py
index 6c72a1d39c55df..863ecc61ddd432 100644
--- a/Lib/test/test_pyrepl/test_reader.py
+++ b/Lib/test/test_pyrepl/test_reader.py
@@ -295,8 +295,8 @@ def test_completions_updated_on_key_press(self):
 
         actual = reader.screen
         self.assertEqual(len(actual), 2)
-        self.assertEqual(actual[0].rstrip(), "itertools.accumulate(")
-        self.assertEqual(actual[1], f"{code}a")
+        self.assertEqual(actual[0], f"{code}a")
+        self.assertEqual(actual[1].rstrip(), "itertools.accumulate(")
 
     def test_key_press_on_tab_press_once(self):
         namespace = {"itertools": itertools}
diff --git a/Lib/test/test_pyrepl/test_windows_console.py b/Lib/test/test_pyrepl/test_windows_console.py
index 4a3b2baf64a944..07eaccd1124cd6 100644
--- a/Lib/test/test_pyrepl/test_windows_console.py
+++ b/Lib/test/test_pyrepl/test_windows_console.py
@@ -329,6 +329,20 @@ def move_right(self, cols=1):
     def erase_in_line(self):
         return ERASE_IN_LINE.encode("utf8")
 
+    def test_multiline_ctrl_z(self):
+        # see gh-126332
+        code = "abcdefghi"
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data='\x1a', raw=bytearray(b'\x1a')),
+                Event(evt="key", data='\x1a', raw=bytearray(b'\x1a')),
+            ],
+        )
+        reader, _ = self.handle_events_narrow(events)
+        self.assertEqual(reader.cxy, (2, 3))
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Lib/test/test_tokenize.py b/Lib/test/test_tokenize.py
index 75710db7d05375..480bff743a9f8a 100644
--- a/Lib/test/test_tokenize.py
+++ b/Lib/test/test_tokenize.py
@@ -1,4 +1,5 @@
 import os
+import re
 import token
 import tokenize
 import unittest
@@ -1819,6 +1820,22 @@ def test_iter_compat(self):
         self.assertEqual(tokenize.untokenize(iter(tokens)), b'Hello ')
 
 
+def contains_ambiguous_backslash(source):
+    """Return `True` if the source contains a backslash on a
+    line by itself. For example:
+
+    a = (1
+        \\
+    )
+
+    Code like this cannot be untokenized exactly. This is because
+    the tokenizer does not produce any tokens for the line containing
+    the backslash and so there is no way to know its indent.
+    """
+    pattern = re.compile(br'\n\s*\\\r?\n')
+    return pattern.search(source) is not None
+
+
 class TestRoundtrip(TestCase):
 
     def check_roundtrip(self, f):
@@ -1829,6 +1846,9 @@ def check_roundtrip(self, f):
         tokenize.untokenize(), and the latter tokenized again to 2-tuples.
         The test fails if the 3 pair tokenizations do not match.
 
+        If the source code can be untokenized unambiguously, the
+        untokenized code must match the original code exactly.
+
         When untokenize bugs are fixed, untokenize with 5-tuples should
         reproduce code that does not contain a backslash continuation
         following spaces.  A proper test should test this.
@@ -1852,6 +1872,13 @@ def check_roundtrip(self, f):
         tokens2_from5 = [tok[:2] for tok in tokenize.tokenize(readline5)]
         self.assertEqual(tokens2_from5, tokens2)
 
+        if not contains_ambiguous_backslash(code):
+            # The BOM does not produce a token so there is no way to preserve it.
+            code_without_bom = code.removeprefix(b'\xef\xbb\xbf')
+            readline = iter(code_without_bom.splitlines(keepends=True)).__next__
+            untokenized_code = tokenize.untokenize(tokenize.tokenize(readline))
+            self.assertEqual(code_without_bom, untokenized_code)
+
     def check_line_extraction(self, f):
         if isinstance(f, str):
             code = f.encode('utf-8')
diff --git a/Lib/tokenize.py b/Lib/tokenize.py
index 1a60fd32a77ea4..9ce95a62d961ba 100644
--- a/Lib/tokenize.py
+++ b/Lib/tokenize.py
@@ -169,6 +169,7 @@ def __init__(self):
         self.prev_row = 1
         self.prev_col = 0
         self.prev_type = None
+        self.prev_line = ""
         self.encoding = None
 
     def add_whitespace(self, start):
@@ -176,14 +177,28 @@ def add_whitespace(self, start):
         if row < self.prev_row or row == self.prev_row and col < self.prev_col:
             raise ValueError("start ({},{}) precedes previous end ({},{})"
                              .format(row, col, self.prev_row, self.prev_col))
-        row_offset = row - self.prev_row
-        if row_offset:
-            self.tokens.append("\\\n" * row_offset)
-            self.prev_col = 0
+        self.add_backslash_continuation(start)
         col_offset = col - self.prev_col
         if col_offset:
             self.tokens.append(" " * col_offset)
 
+    def add_backslash_continuation(self, start):
+        """Add backslash continuation characters if the row has increased
+        without encountering a newline token.
+
+        This also inserts the correct amount of whitespace before the backslash.
+        """
+        row = start[0]
+        row_offset = row - self.prev_row
+        if row_offset == 0:
+            return
+
+        newline = '\r\n' if self.prev_line.endswith('\r\n') else '\n'
+        line = self.prev_line.rstrip('\\\r\n')
+        ws = ''.join(_itertools.takewhile(str.isspace, reversed(line)))
+        self.tokens.append(ws + f"\\{newline}" * row_offset)
+        self.prev_col = 0
+
     def escape_brackets(self, token):
         characters = []
         consume_until_next_bracket = False
@@ -243,8 +258,6 @@ def untokenize(self, iterable):
                     end_line, end_col = end
                     extra_chars = last_line.count("{{") + last_line.count("}}")
                     end = (end_line, end_col + extra_chars)
-            elif tok_type in (STRING, FSTRING_START) and self.prev_type in (STRING, FSTRING_END):
-                self.tokens.append(" ")
 
             self.add_whitespace(start)
             self.tokens.append(token)
@@ -253,6 +266,7 @@ def untokenize(self, iterable):
                 self.prev_row += 1
                 self.prev_col = 0
             self.prev_type = tok_type
+            self.prev_line = line
         return "".join(self.tokens)
 
     def compat(self, token, iterable):
diff --git a/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst b/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst
new file mode 100644
index 00000000000000..8f3f863d93e021
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst
@@ -0,0 +1,2 @@
+Show tab completions menu below the current line, which results in less
+janky behaviour, and fixes a cursor movement bug. Patch by Daniel Hollas
diff --git a/Misc/NEWS.d/next/Library/2024-10-26-16-59-02.gh-issue-125553.4pDLzt.rst b/Misc/NEWS.d/next/Library/2024-10-26-16-59-02.gh-issue-125553.4pDLzt.rst
new file mode 100644
index 00000000000000..291c5e6f6f2181
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-10-26-16-59-02.gh-issue-125553.4pDLzt.rst
@@ -0,0 +1,2 @@
+Fix round-trip invariance for backslash continuations in
+:func:`tokenize.untokenize`.
diff --git a/Misc/NEWS.d/next/Library/2024-11-10-19-45-01.gh-issue-126332.WCCKoH.rst b/Misc/NEWS.d/next/Library/2024-11-10-19-45-01.gh-issue-126332.WCCKoH.rst
new file mode 100644
index 00000000000000..9277797ddc745e
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-11-10-19-45-01.gh-issue-126332.WCCKoH.rst
@@ -0,0 +1 @@
+Fix _pyrepl crash when entering a double CTRL-Z on an overflowing line.