From f14583321de65500957b16d70ccb3b44a43923b8 Mon Sep 17 00:00:00 2001
From: Eric Rakestraw <eric@rakestraw.us>
Date: Mon, 31 Aug 2026 23:49:47 +0000
Subject: [PATCH] Use stable Windows process handles for job assignment

---
 docs/roadmap/implementation.md                |  2 +-
 .../subprocess/process_tree_windows.go        | 22 +++++++++++--------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/docs/roadmap/implementation.md b/docs/roadmap/implementation.md
index a5a2a18..ea7116b 100644
--- a/docs/roadmap/implementation.md
+++ b/docs/roadmap/implementation.md
@@ -273,7 +273,7 @@ error presentation at the existing adapter-facing boundary.
 
 ## Stage 3 — Use The Stable Windows Process Handle
 
-**Status: Pending**
+**Status: Completed**
 
 ### Goal
 
diff --git a/internal/adapters/subprocess/process_tree_windows.go b/internal/adapters/subprocess/process_tree_windows.go
index e3fb6e4..2ddad2c 100644
--- a/internal/adapters/subprocess/process_tree_windows.go
+++ b/internal/adapters/subprocess/process_tree_windows.go
@@ -39,19 +39,23 @@ func (tree *windowsProcessTree) Start(cmd *exec.Cmd) error {
 		return err
 	}
 
-	process, err := windows.OpenProcess(windows.PROCESS_SET_QUOTA|windows.PROCESS_TERMINATE, false, uint32(cmd.Process.Pid))
-	if err == nil {
-		err = windows.AssignProcessToJobObject(job, process)
-		_ = windows.CloseHandle(process)
+	var assignErr error
+	withHandleErr := cmd.Process.WithHandle(func(handle uintptr) {
+		assignErr = windows.AssignProcessToJobObject(job, windows.Handle(handle))
+	})
+	if withHandleErr == nil && assignErr == nil {
+		assignErr = resumeInitialThread(uint32(cmd.Process.Pid))
 	}
-	if err == nil {
-		err = resumeInitialThread(uint32(cmd.Process.Pid))
-	}
-	if err != nil {
+	if withHandleErr != nil || assignErr != nil {
 		killErr := cmd.Process.Kill()
 		waitErr := cmd.Wait()
 		_ = windows.CloseHandle(job)
-		return joinErrors(fmt.Errorf("assign process to job object: %w", err), killErr, waitErr)
+		return joinErrors(
+			fmt.Errorf("acquire process handle for job assignment: %w", withHandleErr),
+			fmt.Errorf("assign process to job object or resume initial thread: %w", assignErr),
+			killErr,
+			waitErr,
+		)
 	}
 
 	tree.job = job