`before_agent` guards `context = runtime.context or {}` at the top, but the
`run_id` stamp on a trailing HumanMessage still read the raw `runtime.context`,
so a None context (thread_id resolved from `config.configurable`) plus a
HumanMessage last message raised `AttributeError: 'NoneType' object has no
attribute 'get'`. Use the guarded local `context` instead.
Adds a regression test.
* Fix Windows backend test compatibility
* Preserve ACP path style on Windows
* Fix installer import ordering
* Address review comments for Windows fixes
---------
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>