fix: networking / services / and testing

internal/modules/services/services.go

@@ -3,14 +3,22 @@ package services
 import (
 	"context"
 	"encoding/json"
+	"os/exec"
 	"regexp"
 	"strings"
+	"syscall"
 
 	"nadir/internal/oscmd"
 
 	"github.com/danielgtaylor/huma/v2"
 )
 
+// selfUnit is nadir's own systemd unit name. Acting on it via the normal
+// synchronous path would have systemd SIGTERM the very process serving the
+// request, so the client sees a dropped connection / 500 even though the
+// action succeeded. We detach those calls into a Setsid subprocess instead.
+const selfUnit = "nadir"
+
 const tagServices = "Services"
 
 var (
@@ -136,6 +144,9 @@ func registerServices(api huma.API) {
 			if err := ensureExists(in.Unit); err != nil {
 				return nil, err
 			}
+			if isSelf(in.Unit) {
+				return runDetached(c.action, in.Unit)
+			}
 			if _, err := oscmd.Run("systemctl", c.action, "--", in.Unit); err != nil {
 				return nil, huma.Error500InternalServerError("systemctl "+c.action+" failed", err)
 			}
@@ -144,6 +155,27 @@ func registerServices(api huma.API) {
 	}
 }
 
+// isSelf reports whether unit names nadir's own service, with or without the
+// .service suffix.
+func isSelf(unit string) bool {
+	return unit == selfUnit || unit == selfUnit+".service"
+}
+
+// runDetached fires systemctl in a new session so a "systemctl restart nadir"
+// (or stop) doesn't kill its own caller before the HTTP response is written.
+// Returns success once the subprocess has *started* — the actual systemd
+// operation may complete after the response is sent, which is the whole point.
+func runDetached(action, unit string) (*oscmd.StatusOutput, error) {
+	cmd := exec.Command("systemctl", action, "--", unit)
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
+	if err := cmd.Start(); err != nil {
+		return nil, huma.Error500InternalServerError("could not start detached systemctl", err)
+	}
+	// Reap in the background so the child doesn't become a zombie.
+	go cmd.Wait()
+	return oscmd.OK(), nil
+}
+
 // validateUnit guards against empty, flag-like, or malformed unit names.
 func validateUnit(unit string) error {
 	if unit == "" || strings.HasPrefix(unit, "-") || !unitNameRe.MatchString(unit) {

internal/modules/services/services_test.go

@@ -19,3 +19,22 @@ func TestValidateUnit(t *testing.T) {
 		}
 	}
 }
+
+// TestIsSelf pins the dispatch that detaches stop/restart-of-self into a
+// Setsid subprocess. Both "nadir" and "nadir.service" must match; anything
+// else (including substrings) must not, or unrelated services would also get
+// detached and bypass the synchronous error path.
+func TestIsSelf(t *testing.T) {
+	yes := []string{"nadir", "nadir.service"}
+	for _, u := range yes {
+		if !isSelf(u) {
+			t.Errorf("isSelf(%q) = false, want true", u)
+		}
+	}
+	no := []string{"", "sshd.service", "nadir-something.service", "nadir.timer", "not-nadir.service"}
+	for _, u := range no {
+		if isSelf(u) {
+			t.Errorf("isSelf(%q) = true, want false", u)
+		}
+	}
+}