[Windows ARM64] Isolate build profiles and use native shutdown primitives

[arif-ahmed-nv]

Summary

• isolate setuptools and configure-only outputs by CUDA architecture profile
• import one canonical ARM64 MSVC environment and validate the selected compiler
• validate and export the standard protobuf include tree required by the Rust frontend
• use native Windows signal registration and forceful process-tree termination

Why

#2 established the native Windows ARM64 build and runtime baseline. This PR addresses the remaining correctness and reproducibility gaps found while repeatedly building and serving that branch.

Architecture-profile isolation

The build script supports both a portable CUDA profile (12.0+PTX;10.3a) and an exact RTX Spark profile (12.1a). These architecture selections affect the native code embedded in the wheel.

WheelDir controls only where the completed wheel is written. Without a separate setuptools build base, consecutive builds still reuse the same build/ directory, including CMake state and previously compiled native objects. A build for one CUDA architecture profile can therefore consume artifacts produced for another profile, even though the output directory and wheel version identify the new profile.

This PR derives an isolated build base and configure-only directory from CudaArchList, while allowing both paths to be overridden explicitly. This makes repeated portable and device-specific builds from the same source tree reproducible and prevents profile names from diverging from the native objects packaged inside the wheel.

Deterministic ARM64 toolchain selection

Windows ARM64 development machines can have ARM64, x64, and emulated toolchains installed together. Importing only part of the vcvarsall.bat environment can leave the wrong cl.exe earlier in PATH, leading to wrong-machine objects or link failures later in a long build.

The script now captures the post-vcvarsall PATH explicitly using delayed expansion, imports the complete environment, and verifies that the selected compiler targets ARM64 and comes from the requested MSVC toolset.

The Rust frontend also requires more than a working protoc.exe: the frontend's .proto schemas import Protobuf well-known types such as google/protobuf/struct.proto. The script now resolves and validates the matching standard include tree and exports it through PROTOC_INCLUDE, so a missing or mismatched Protobuf installation fails early with an actionable error.

Native Windows server lifecycle

Two Unix assumptions remain in shared runtime code:

• Windows asyncio event loops do not implement loop.add_signal_handler, so server startup can raise NotImplementedError.
• Windows does not define Unix SIGKILL, so forceful process-tree cleanup cannot use the existing os.kill(..., SIGKILL) path.

The Windows branches use signal.signal for shutdown registration and psutil.Process.kill() for children followed by the parent. Non-Windows behavior is unchanged.

Together, these changes make the Windows ARM64 branch repeatably buildable across CUDA profiles and allow the resulting server to start and shut down through native Windows APIs. The build and runtime changes are separated into two commits and have focused regression coverage.

Validation

• tests/entrypoints/test_launcher.py: 2 passed
• tests/utils_/test_system_utils.py: 3 passed
• git diff --check: passed
• extracted Import-Arm64MsvcEnvironment from the submitted script and resolved HostARM64\ARM64\cl.exe from MSVC 14.51.36231
• built and installed both Windows ARM64 wheels from the same source tree using the isolated profile layout:
  • portable 12.0+PTX;10.3a
  • Spark-native 12.1a
• both wheel profiles started the API server and returned HTTP 200 from /v1/models and /v1/chat/completions

The focused pytest run used the compiled Windows ARM64 extension from the validated wheel environment because the review checkout itself does not contain generated .pyd files.

Scope

There are no model-specific paths, internal package URLs, or NVIDIA-internal artifacts in this change.

AI assistance was used to prepare and test this change. The submitter reviewed the rationale for each hunk and directed the validation on the target Windows ARM64 system.

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[arif-ahmed-nv]

@vortex-captain @khmyznikov Would appreciate your review on this PR.

[vortex-captain]

Thanks @arif-ahmed-nv ! LGTM