diff --git a/IPython/__init__.py b/IPython/__init__.py
index 91cf9ae444..9c87dc51be 100644
--- a/IPython/__init__.py
+++ b/IPython/__init__.py
@@ -21,6 +21,7 @@
 
 import sys
 import warnings
+from typing import Any
 
 #-----------------------------------------------------------------------------
 # Setup everything
@@ -91,7 +92,7 @@ def embed_kernel(module=None, local_ns=None, **kwargs):
     from ipykernel.embed import embed_kernel as real_embed_kernel
     real_embed_kernel(module=module, local_ns=local_ns, **kwargs)
 
-def start_ipython(argv=None, **kwargs):
+def start_ipython(argv: list[str] | None = None, **kwargs: Any) -> Any:
     """Launch a normal IPython instance (as opposed to embedded)
 
     `IPython.embed()` puts a shell in a particular calling scope,
diff --git a/IPython/core/async_helpers.py b/IPython/core/async_helpers.py
index 4eac709dd3..2eaaa52ce8 100644
--- a/IPython/core/async_helpers.py
+++ b/IPython/core/async_helpers.py
@@ -15,7 +15,7 @@
 import inspect
 from functools import wraps
 
-_asyncio_event_loop = None
+_asyncio_event_loop: asyncio.AbstractEventLoop | None = None
 
 
 def get_asyncio_loop():
diff --git a/IPython/core/doctb.py b/IPython/core/doctb.py
index 4fcf378d66..c7be8453a6 100644
--- a/IPython/core/doctb.py
+++ b/IPython/core/doctb.py
@@ -330,7 +330,10 @@ def get_records(self, etb: TracebackType, context: int, tb_offset: int) -> Any:
         before = context - after
         if self.has_colors:
             base_style = theme_table[self._theme_name].as_pygments_style()
-            style = stack_data.style_with_executing_node(base_style, self.tb_highlight)
+            # stack_data ships without type annotations
+            style = stack_data.style_with_executing_node(  # type: ignore[no-untyped-call]
+                base_style, self.tb_highlight
+            )
             formatter = Terminal256Formatter(style=style)
         else:
             formatter = None
diff --git a/IPython/core/history.py b/IPython/core/history.py
index ae78b06852..5495971b82 100644
--- a/IPython/core/history.py
+++ b/IPython/core/history.py
@@ -84,16 +84,16 @@ class DummyDB:
     def execute(*args: typing.Any, **kwargs: typing.Any) -> list:
         return []
 
-    def commit(self, *args, **kwargs):  # type: ignore [no-untyped-def]
+    def commit(self, *args: typing.Any, **kwargs: typing.Any) -> None:
         pass
 
-    def __enter__(self, *args, **kwargs):  # type: ignore [no-untyped-def]
+    def __enter__(self, *args: typing.Any, **kwargs: typing.Any) -> None:
         pass
 
-    def __exit__(self, *args, **kwargs):  # type: ignore [no-untyped-def]
+    def __exit__(self, *args: typing.Any, **kwargs: typing.Any) -> None:
         pass
 
-    def close(self, *args, **kwargs):  # type: ignore [no-untyped-def]
+    def close(self, *args: typing.Any, **kwargs: typing.Any) -> None:
         pass
 
 
diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index 2799d0ba29..8de4f8d85a 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -482,7 +482,9 @@ def _enable_html_pager_changed(self, change):
         if change['new']:
             warn("`enable_html_pager` is provisional since IPython 5.0 and might change in future versions.", ProvisionalWarning)
 
-    data_pub_class = None
+    # Not a traitlets trait: a plain class-attribute override point for
+    # subclasses that want to set a data_pub class.
+    data_pub_class: type | None = None
 
     exit_now = Bool(False)
     exiter = Instance(ExitAutocall)
@@ -616,7 +618,7 @@ def profile(self):
     _post_execute = Dict()
 
     # Tracks any GUI loop loaded for pylab
-    pylab_gui_select = None
+    pylab_gui_select: str | None = None
 
     last_execution_succeeded = Bool(True, help='Did last executed command succeeded')
 
diff --git a/IPython/core/macro.py b/IPython/core/macro.py
index 11314d4a16..a00c4a0d6b 100644
--- a/IPython/core/macro.py
+++ b/IPython/core/macro.py
@@ -10,8 +10,6 @@
 
 import re
 
-from IPython.utils.encoding import DEFAULT_ENCODING
-
 coding_declaration = re.compile(r"#\s*coding[:=]\s*([-\w.]+)")
 
 class Macro:
@@ -23,17 +21,8 @@ class Macro:
 
     def __init__(self, code: str):
         """store the macro value, as a single string which can be executed"""
-        lines = []
-        enc = None
-        for line in code.splitlines():
-            coding_match = coding_declaration.match(line)
-            if coding_match:
-                enc = coding_match.group(1)
-            else:
-                lines.append(line)
+        lines = [line for line in code.splitlines() if not coding_declaration.match(line)]
         code = "\n".join(lines)
-        if isinstance(code, bytes):
-            code = code.decode(enc or DEFAULT_ENCODING)
         self.value = code + '\n'
 
     def __str__(self):
diff --git a/IPython/core/profiledir.py b/IPython/core/profiledir.py
index ccbdf01d01..915f931b99 100644
--- a/IPython/core/profiledir.py
+++ b/IPython/core/profiledir.py
@@ -160,9 +160,6 @@ def copy_config_file(self, config_file: str, path: Path, overwrite=False) -> boo
         dst = Path(os.path.join(self.location, config_file))
         if dst.exists() and not overwrite:
             return False
-        if path is None:
-            path = os.path.join(get_ipython_package_dir(), 'core', 'profile', 'default')
-        assert isinstance(path, Path)
         src = path / config_file
         shutil.copy(src, dst)
         return True
diff --git a/IPython/core/tbtools.py b/IPython/core/tbtools.py
index 2e0440f700..a74981a960 100644
--- a/IPython/core/tbtools.py
+++ b/IPython/core/tbtools.py
@@ -58,10 +58,6 @@ def get_line_number_of_frame(frame: types.FrameType) -> int:
         if the file is not available.
     """
     filename = frame.f_code.co_filename
-    if filename is None:
-        print("No file....")
-        lines, first = inspect.getsourcelines(frame)
-        return first + len(lines)
     return count_lines_in_py_file(filename)
 
 
@@ -295,7 +291,7 @@ class FrameInfo:
     # number of context lines to use
     context: int | None
     raw_lines: list[str]
-    _sd: stack_data.core.FrameInfo
+    _sd: stack_data.core.FrameInfo | stack_data.core.RepeatedFrames | None
     frame: Any
 
     @classmethod
@@ -344,8 +340,10 @@ def __init__(
 
     @property
     def variables_in_executing_piece(self) -> list[Any]:
+        # callers only reach here once RepeatedFrames-backed instances have
+        # been filtered out (see doctb.py/ultratb.py format_record)
         if self._sd is not None:
-            return self._sd.variables_in_executing_piece  # type:ignore[misc]
+            return self._sd.variables_in_executing_piece  # type:ignore[misc,union-attr]
         else:
             return []
 
@@ -353,9 +351,11 @@ def variables_in_executing_piece(self) -> list[Any]:
     def lines(self) -> list[Any]:
         from executing.executing import NotOneValueFound
 
+        # callers only reach here once RepeatedFrames-backed instances have
+        # been filtered out (see doctb.py/ultratb.py format_record)
         assert self._sd is not None
         try:
-            return self._sd.lines  # type: ignore[misc]
+            return self._sd.lines  # type: ignore[misc,union-attr]
         except NotOneValueFound:
 
             class Dummy:
@@ -369,8 +369,10 @@ def render(self, *, pygmented: bool) -> str:
 
     @property
     def executing(self) -> Any:
+        # callers only reach here once RepeatedFrames-backed instances have
+        # been filtered out (see doctb.py/ultratb.py format_record)
         if self._sd is not None:
-            return self._sd.executing
+            return self._sd.executing  # type: ignore[union-attr]
         else:
             return None
 
diff --git a/IPython/core/ultratb.py b/IPython/core/ultratb.py
index e2cea4ef72..487f1a489a 100644
--- a/IPython/core/ultratb.py
+++ b/IPython/core/ultratb.py
@@ -175,13 +175,16 @@ def structured_traceback(
         """
         # This is a workaround to get chained_exc_ids in recursive calls
         # etb should not be a tuple if structured_traceback is not recursive
+        # (see the recursive self.structured_traceback() call below), and can
+        # also be a pre-built list of frames per the docstring above; neither
+        # is expressible in the public `TracebackType | None` signature.
         if isinstance(etb, tuple):
-            etb, chained_exc_ids = etb
+            etb, chained_exc_ids = etb  # type: ignore[unreachable]
         else:
             chained_exc_ids = set()
         elist: list[Any]
         if isinstance(etb, list):
-            elist = etb
+            elist = etb  # type: ignore[unreachable]
         elif etb is not None:
             elist = self._extract_tb(etb)  # type: ignore[assignment]
         else:
@@ -1256,11 +1259,14 @@ def structured_traceback(
         context: int = 5,
     ) -> list[str]:
         # tb: TracebackType or tupleof tb types ?
+        # etype can be None when called as structured_traceback(*sys.exc_info())
+        # with no active exception; etb can be a tuple for a chained exception.
+        # Neither is expressible in the public signature above.
         if etype is None:
-            etype, evalue, etb = sys.exc_info()
+            etype, evalue, etb = sys.exc_info()  # type: ignore[unreachable]
         if isinstance(etb, tuple):
             # tb is a tuple if this is a chained exception.
-            self.tb = etb[0]
+            self.tb = etb[0]  # type: ignore[unreachable]
         else:
             self.tb = etb
         return FormattedTB.structured_traceback(
diff --git a/IPython/paths.py b/IPython/paths.py
index 1a95848bfa..d86d480c5a 100644
--- a/IPython/paths.py
+++ b/IPython/paths.py
@@ -109,7 +109,7 @@ def get_ipython_module_path(module_str):
     return the_path
 
 
-def locate_profile(profile='default'):
+def locate_profile(profile: str = "default") -> str:
     """Find the path to the folder associated with a given profile.
 
     I.e. find $IPYTHONDIR/profile_whatever.
diff --git a/IPython/utils/PyColorize.py b/IPython/utils/PyColorize.py
index 9446a5eee1..da749b5801 100644
--- a/IPython/utils/PyColorize.py
+++ b/IPython/utils/PyColorize.py
@@ -435,13 +435,16 @@ def theme_name(self, value: str) -> None:
 
     @property
     def style(self) -> str:
+        # `style` was renamed `theme_name`; this always raises to catch
+        # leftover callers of the old name. Body kept only to satisfy the -> str
+        # return type.
         assert False
-        return self._theme_name
+        return self._theme_name  # type: ignore[unreachable]
 
     @style.setter
     def style(self, val: str) -> None:
         assert False
-        assert val == val.lower()
+        assert val == val.lower()  # type: ignore[unreachable]
         self._theme_name = val
 
     def format(self, raw: str, out: Any = None) -> str | None:
diff --git a/IPython/utils/module_paths.py b/IPython/utils/module_paths.py
index 1ec2e38e49..52637aaf10 100644
--- a/IPython/utils/module_paths.py
+++ b/IPython/utils/module_paths.py
@@ -69,7 +69,7 @@ def find_mod(module_name: str) -> str | None | importlib.abc.Loader:
     if module_path is None:
         # built-in/frozen modules use their own meta_path finder as loader
         if spec.loader is not None and spec.loader in sys.meta_path:  # type: ignore[comparison-overlap]
-            return spec.loader
+            return spec.loader  # type: ignore[unreachable]
         return None
     else:
         split_path = module_path.split(".")
diff --git a/pyproject.toml b/pyproject.toml
index a73f42f149..384c135333 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -116,8 +116,8 @@ exclude = [
    'IPython/core/debugger_backport.py',
 ]
 check_untyped_defs = true
-# disallow_untyped_calls = true
-# disallow_untyped_decorators = true
+disallow_untyped_calls = true
+disallow_untyped_decorators = true
 # ignore_errors = false
 # ignore_missing_imports = false
 disallow_incomplete_defs = true
@@ -125,6 +125,7 @@ disallow_untyped_defs = true
 warn_redundant_casts = true
 warn_unused_ignores = true
 strict_equality = true
+warn_unreachable = true
 enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]
 
 [[tool.mypy.overrides]]