Guard get_ipython() being Optional (fixes mypy on master) (#1088)

The linters workflow has been failing on master since IPython 9.16
started annotating get_ipython() as returning Optional[InteractiveShell]
(history_manager is optional too). mypy 2.3 reports four union-attr
errors in scalene_tracing.py and scalene_magics.py; the existing
"type: ignore[no-untyped-call, unused-ignore]" on those lines does not
cover that error code, and says so.

No commit caused this -- master's last linters run (2026-07-05) passed
and nothing has landed since, so it broke when CI's unpinned
"pip install mypy ruff ..." picked up the newer versions.

Guard both levels. _handle_jupyter_cell() returns False without a live
shell, falling through to the ordinary filename rules, which is the
behavior it already had when the cell regex didn't match. run_code()
prints a plain message and returns; neither value can actually be None
there, since a magic only runs inside a live shell.

The ignore comments stay put: on older IPython, get_ipython() is
untyped, so no-untyped-call still applies, and unused-ignore keeps the
comment valid once it doesn't.

Verified in a venv pinned to CI's exact versions (mypy 2.3.0, IPython
9.16.0): 4 errors before, clean after, ruff clean. Also re-checked
against the older pair (mypy 1.19.0, IPython 9.9.0) so the fix holds in
both directions. Behavior spot-checked for all three shapes -- live
shell (recovers the cell and returns True), get_ipython() None, and
history_manager None. Full pytest suite: 442 passed, 13 skipped.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: emeryberger

scalene/scalene_magics.py

@@ -40,7 +40,20 @@ def run_code(self, args: ScaleneArguments, code: str) -> None:
             # Create a file to hold the supplied code.
             # We encode the cell number in the string for later recovery.
             # The length of the history buffer lets us find the most recent string (this one).
-            filename = f"_ipython-input-{len(IPython.get_ipython().history_manager.input_hist_raw)-1}-profile"  # type: ignore[no-untyped-call,unused-ignore]
+            #
+            # IPython >= 9.16 annotates get_ipython() as returning
+            # Optional[InteractiveShell], and history_manager is itself
+            # optional. Neither can be None in practice here — a magic only
+            # runs inside a live shell — but we can't index the history
+            # without it, so say so plainly instead of raising AttributeError.
+            shell = IPython.get_ipython()  # type: ignore[no-untyped-call,unused-ignore]
+            history = shell.history_manager if shell is not None else None
+            if history is None:
+                print(
+                    "Scalene: no IPython history is available, so this cell cannot be profiled."
+                )
+                return
+            filename = f"_ipython-input-{len(history.input_hist_raw)-1}-profile"
             with open(filename, "w+") as tmpfile:
                 tmpfile.write(code)
             args.memory = (

scalene/scalene_tracing.py

@@ -154,9 +154,16 @@ def _handle_jupyter_cell(self, filename: Filename) -> bool:
             import IPython
 
             if result := re.match(r"_ipython-input-([0-9]+)-.*", filename):
-                cell_contents = IPython.get_ipython().history_manager.input_hist_raw[  # type: ignore[no-untyped-call,unused-ignore]
-                    int(result[1])
-                ]
+                shell = IPython.get_ipython()  # type: ignore[no-untyped-call,unused-ignore]
+                # IPython >= 9.16 annotates get_ipython() as returning
+                # Optional[InteractiveShell], and history_manager is itself
+                # optional (absent when history is disabled). Without a live
+                # shell there is no cell to recover, so fall through to the
+                # ordinary filename rules rather than crashing.
+                history = shell.history_manager if shell is not None else None
+                if history is None:
+                    return False
+                cell_contents = history.input_hist_raw[int(result[1])]
                 with open(filename, "w+") as f:
                     f.write(cell_contents)
                 return True