The test created a HistoryManager backed by a real file but never
stopped its HistorySavingThread. The thread briefly holds a strong
reference to the manager inside its polling loop, so the instance
could survive the gc.collect() in the hmmax fixture teardown,
making the instance-leak assertion fail intermittently.

Stop the saving thread and close the database like the other tests
in this file do, and drop the unreachable `HistoryManager.__max_inst`
assignment that name-mangling never applied anyway.

Fixes #15161

https://claude.ai/code/session_01AtmUVnQwZfjDBuUzF7TdGh

Honor PEP 263 coding cookies when reading module sources for the
autoreload diffing logic, the way the import system does, instead of
assuming utf-8. Sources that declare another encoding were read as
empty (the UnicodeDecodeError is caught and logged), disabling
hot-patching for those modules, and the logged traceback was noisy on
the first %load_ext autoreload.

The regression test fails with the previous explicit utf-8 reading.

Closes #15193 (the original cp1252 crash reported there was already
fixed by reading with an explicit encoding, this handles the
remaining non-utf-8 sources).

https://claude.ai/code/session_01AtmUVnQwZfjDBuUzF7TdGh

inspect_object is not called anywhere in IPython anymore, so
registering handlers on it has no effect, and a search of public
repositories found no external users (unlike complete_object, which
pyflyby, riptable and maiev register completers on, and which is
unchanged).

Emit a DeprecationWarning through a module __getattr__ so that simply
importing the name warns, which also covers consumers that only call
.register().

First step towards #15068.

https://claude.ai/code/session_01AtmUVnQwZfjDBuUzF7TdGh

xml.etree.ElementTree.ParseError is a SyntaxError subclass that
leaves .text set to None; IPython 9.6.0 raised an AssertionError in
ListTB._format_exception_only when rendering it. The guard was added
as part of #15012, but without a test; this locks the behavior in.

The test fails if the None check in _format_exception_only is
removed.

Closes #15024

https://claude.ai/code/session_01AtmUVnQwZfjDBuUzF7TdGh

…h quoting

oinspect: guard __custom_documentations__ lookup with isinstance(dict) so
objects like polars Expr (which return self for any attribute access via
__getattr__) no longer raise TypeError when inspected with ?. Fixes #15072.

oinspect: fix inspect.Parameter.empty comparison in MIME-hook path; the
previous code accidentally compared against the property descriptor object
rather than the sentinel, making the required-parameter filter a no-op.

test_interactiveshell: wrap sys.executable and self.fname in shlex.quote()
so test_exit_code_signal survives when the source path contains spaces.
Fixes #15100.

https://claude.ai/code/session_01VPnGTgifZ8HMAfiqEVftjj

https://claude.ai/code/session_01LFpqCq9eJbgFG6jhwtvFcy