fix: close workspace preprocessing contract gaps

tools/thothctl/internal/compose/runner_test.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -123,6 +124,35 @@ func TestRunnerBoundedCancellationWinsOverChildKill(t *testing.T) {
 	}
 }
 
+func TestRunnerBoundedKillsGrandchildProcess(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("shell process-group fixture is Unix-specific")
+	}
+	pidFile := filepath.Join(t.TempDir(), "grandchild.pid")
+	script := "#!/bin/sh\n(sleep 30) &\nprintf '%s' $! > '" + pidFile + "'\nwhile :; do printf x; done\n"
+	runner := NewRunner(writeExecutable(t, script))
+	_, err := runner.RunBounded(context.Background(), nil, nil, CaptureLimits{StdoutBytes: 64, StderrBytes: 64})
+	if !errors.Is(err, ErrOutputLimit) {
+		t.Fatalf("err = %v", err)
+	}
+	pidBytes, readErr := os.ReadFile(pidFile)
+	if readErr != nil {
+		t.Fatal(readErr)
+	}
+	pid, err := strconv.Atoi(strings.TrimSpace(string(pidBytes)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		if !processExists(pid) {
+			return
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	t.Fatalf("grandchild pid %d remained alive after owned-process termination", pid)
+}
+
 func TestRunnerBoundedTerminatesGrandchildHoldingPipe(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.Skip("shell process-group fixture is Unix-specific")