fix: complete target diagnostics and reset inspection

internal/gnome/gnome_test.go

@@ -55,6 +55,9 @@ func (r *fakeRunner) Run(_ context.Context, c gnome.Command) (string, error) {
 		}
 		return value + "\n", nil
 	}
+	if len(c.Args) == 3 && c.Args[0] == "writable" {
+		return "true\n", nil
+	}
 	if len(c.Args) == 4 && c.Args[0] == "set" {
 		r.values[c.Args[1]+" "+c.Args[2]] = c.Args[3]
 		return "", nil
@@ -105,6 +108,29 @@ func active() *profile.Profile {
 	return &profile.Profile{Name: "office", Mode: profile.AdvancedMode, HTTPURL: "http://proxy.example:8080", HTTPSURL: "http://secure.example:8443", AllURL: "socks5://socks.example:1080", Bypass: []string{"localhost", ".example.com", "10.0.0.0/8", "2001:db8::1"}}
 }
 
+func TestDiagnosticChecksCoverCommandSchemasSessionAndAuthorityWithoutMutation(t *testing.T) {
+	r, state := newRunner(), &memoryState{}
+	a := adapter(r, state)
+	checks := a.DiagnosticChecks(context.Background(), active())
+	for _, name := range []string{"required command", "required schemas", "desktop session", "write authority"} {
+		found := false
+		for _, check := range checks {
+			found = found || check.Name == name
+		}
+		if !found {
+			t.Errorf("diagnostics missing %q: %#v", name, checks)
+		}
+	}
+	for _, call := range r.calls {
+		if len(call.Args) > 0 && call.Args[0] == "set" {
+			t.Fatalf("diagnostics mutated GNOME settings: %#v", call)
+		}
+	}
+	if state.data != nil {
+		t.Fatalf("diagnostics wrote GNOME recovery state: %q", state.data)
+	}
+}
+
 func TestGNOMEAdapterRunsReusableTargetContract(t *testing.T) {
 	targettest.Run(t, func(t *testing.T) targettest.Fixture {
 		r, state := newRunner(), &memoryState{}