win32-jobobject-tree-kill

name	win32-jobobject-tree-kill
description	Kill a spawned Windows process tree from C# with a Win32 Job Object.

Win32 JobObject tree kill

Use when

• A service spawns a process that may spawn descendants.
• User cancel or timeout must kill the full tree.
• No external NuGet dependency is allowed.

C# pattern

1. Wrap P/Invoke in an internal static helper.
2. Create a job with CreateJobObject.
3. Set JOBOBJECT_EXTENDED_LIMIT_INFORMATION.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE.
4. Start the child process.
5. Assign process.Handle using AssignProcessToJobObject immediately after start.
6. On cancel or timeout, call TerminateJobObject(job, 1).
7. Close the job handle in finally.

P/Invoke surface

CreateJobObject
SetInformationJobObject
AssignProcessToJobObject
TerminateJobObject
CloseHandle
JOBOBJECT_EXTENDED_LIMIT_INFORMATION
JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE

Copilot Booster location

• Helper: src/Services/Win32JobObject.cs
• Production use: src/Services/ProcessRunner.cs
• Contract: IProcessRunner.RunAsync(...) -> ProcessResult.WasKilled

Classification rule

• WasKilled == true && ct.IsCancellationRequested means user cancel. Log outcome=cancelled, leave failure class null.
• WasKilled == true && !ct.IsCancellationRequested means timeout.