Fix control config persistence for restart-only changes

internal/control/control.go

@@ -714,7 +714,20 @@ func (s *Server) handleConfig(w http.ResponseWriter, r *http.Request) {
 				return
 			}
 		}
-		// Commit the server snapshot only after validation and any required live update succeeded.
+		// Persist the validated config snapshot when a config saver is available.
+		// This ensures restart-required UI changes survive process restarts instead
+		// of only updating the in-memory snapshot.
+		s.mu.RLock()
+		save := s.saveConfig
+		s.mu.RUnlock()
+		if save != nil {
+			if err := save(next); err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+		}
+		// Commit the server snapshot only after validation, optional persistence,
+		// and any required live update succeeded.
 		s.mu.Lock()
 		s.cfg = next
 		s.mu.Unlock()

internal/control/control_test.go

@@ -740,6 +740,117 @@ func TestConfigPatchUpdatesSnapshot(t *testing.T) {
 	}
 }
 
+func TestConfigPatchPersistsRestartRequiredFieldsWhenSaverConfigured(t *testing.T) {
+	cfg := cfgpkg.Default()
+	srv := NewServer(cfg)
+
+	dir := t.TempDir()
+	configPath := filepath.Join(dir, "saved.json")
+	if err := cfgpkg.Save(configPath, cfg); err != nil {
+		t.Fatalf("seed config: %v", err)
+	}
+	srv.SetConfigSaver(func(next cfgpkg.Config) error {
+		return cfgpkg.Save(configPath, next)
+	})
+
+	rec := httptest.NewRecorder()
+	body := []byte(`{
+		"preEmphasisTauUS":75,
+		"audioGain":1.5,
+		"pi":"BEEF",
+		"pty":10,
+		"ms":false,
+		"ctEnabled":false,
+		"rtPlusEnabled":false,
+		"rtPlusSeparator":"/",
+		"ptyn":"ALTROCK",
+		"lps":"My Radio Station",
+		"ertEnabled":true,
+		"ert":"Grüezi mitenand",
+		"rds2Enabled":true,
+		"stationLogoPath":"C:\\logo.png",
+		"af":[93.3,95.7],
+		"bs412Enabled":true,
+		"bs412ThresholdDBr":0.5,
+		"mpxGain":1.3,
+		"compositeClipperIterations":4,
+		"compositeClipperSoftKnee":0.22,
+		"compositeClipperLookaheadMs":1.4
+	}`)
+	srv.Handler().ServeHTTP(rec, newConfigPostRequest(body))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status: %d body=%s", rec.Code, rec.Body.String())
+	}
+
+	saved, err := cfgpkg.Load(configPath)
+	if err != nil {
+		t.Fatalf("load saved config: %v", err)
+	}
+	if saved.FM.PreEmphasisTauUS != 75 {
+		t.Fatalf("expected saved preEmphasisTauUS=75, got %v", saved.FM.PreEmphasisTauUS)
+	}
+	if saved.Audio.Gain != 1.5 {
+		t.Fatalf("expected saved audio.gain=1.5, got %v", saved.Audio.Gain)
+	}
+	if saved.RDS.PI != "BEEF" {
+		t.Fatalf("expected saved rds.pi=BEEF, got %q", saved.RDS.PI)
+	}
+	if saved.RDS.PTY != 10 {
+		t.Fatalf("expected saved rds.pty=10, got %v", saved.RDS.PTY)
+	}
+	if saved.RDS.MS != false {
+		t.Fatalf("expected saved rds.ms=false, got %v", saved.RDS.MS)
+	}
+	if saved.RDS.CTEnabled != false {
+		t.Fatalf("expected saved rds.ctEnabled=false, got %v", saved.RDS.CTEnabled)
+	}
+	if saved.RDS.RTPlusEnabled != false {
+		t.Fatalf("expected saved rds.rtPlusEnabled=false, got %v", saved.RDS.RTPlusEnabled)
+	}
+	if saved.RDS.RTPlusSeparator != "/" {
+		t.Fatalf("expected saved rds.rtPlusSeparator='/', got %q", saved.RDS.RTPlusSeparator)
+	}
+	if saved.RDS.PTYN != "ALTROCK" {
+		t.Fatalf("expected saved rds.ptyn=ALTROCK, got %q", saved.RDS.PTYN)
+	}
+	if saved.RDS.LPS != "My Radio Station" {
+		t.Fatalf("expected saved rds.lps, got %q", saved.RDS.LPS)
+	}
+	if saved.RDS.ERTEnabled != true {
+		t.Fatalf("expected saved rds.ertEnabled=true, got %v", saved.RDS.ERTEnabled)
+	}
+	if saved.RDS.ERT != "Grüezi mitenand" {
+		t.Fatalf("expected saved rds.ert, got %q", saved.RDS.ERT)
+	}
+	if saved.RDS.RDS2Enabled != true {
+		t.Fatalf("expected saved rds.rds2Enabled=true, got %v", saved.RDS.RDS2Enabled)
+	}
+	if saved.RDS.StationLogoPath != "C:\\logo.png" {
+		t.Fatalf("expected saved rds.stationLogoPath, got %q", saved.RDS.StationLogoPath)
+	}
+	if len(saved.RDS.AF) != 2 || saved.RDS.AF[0] != 93.3 || saved.RDS.AF[1] != 95.7 {
+		t.Fatalf("expected saved rds.af=[93.3 95.7], got %v", saved.RDS.AF)
+	}
+	if !saved.FM.BS412Enabled {
+		t.Fatalf("expected saved bs412Enabled=true, got false")
+	}
+	if saved.FM.BS412ThresholdDBr != 0.5 {
+		t.Fatalf("expected saved bs412ThresholdDBr=0.5, got %v", saved.FM.BS412ThresholdDBr)
+	}
+	if saved.FM.MpxGain != 1.3 {
+		t.Fatalf("expected saved fm.mpxGain=1.3, got %v", saved.FM.MpxGain)
+	}
+	if saved.FM.CompositeClipper.Iterations != 4 {
+		t.Fatalf("expected saved compositeClipper.iterations=4, got %v", saved.FM.CompositeClipper.Iterations)
+	}
+	if saved.FM.CompositeClipper.SoftKnee != 0.22 {
+		t.Fatalf("expected saved compositeClipper.softKnee=0.22, got %v", saved.FM.CompositeClipper.SoftKnee)
+	}
+	if saved.FM.CompositeClipper.LookaheadMs != 1.4 {
+		t.Fatalf("expected saved compositeClipper.lookaheadMs=1.4, got %v", saved.FM.CompositeClipper.LookaheadMs)
+	}
+}
+
 func TestConfigPatchEngineRejectsDoesNotUpdateSnapshot(t *testing.T) {
 	srv := NewServer(cfgpkg.Default())
 	srv.SetTXController(&fakeTXController{updateErr: errors.New("boom")})

internal/control/server_test.go

@@ -18,11 +18,14 @@ func TestNewHTTPServerConfig(t *testing.T) {
 	if srv.Handler != handler {
 		t.Fatalf("expected handler to be preserved")
 	}
-	if srv.ReadTimeout != defaultReadTimeout {
-		t.Fatalf("expected read timeout %s, got %s", defaultReadTimeout, srv.ReadTimeout)
+	if srv.ReadTimeout != 0 {
+		t.Fatalf("expected read timeout to remain disabled for streaming requests, got %s", srv.ReadTimeout)
 	}
-	if srv.WriteTimeout != defaultWriteTimeout {
-		t.Fatalf("expected write timeout %s, got %s", defaultWriteTimeout, srv.WriteTimeout)
+	if srv.WriteTimeout != 0 {
+		t.Fatalf("expected write timeout to remain disabled for streaming requests, got %s", srv.WriteTimeout)
+	}
+	if srv.ReadHeaderTimeout != defaultReadHeaderTimeout {
+		t.Fatalf("expected read header timeout %s, got %s", defaultReadHeaderTimeout, srv.ReadHeaderTimeout)
 	}
 	if srv.IdleTimeout != defaultIdleTimeout {
 		t.Fatalf("expected idle timeout %s, got %s", defaultIdleTimeout, srv.IdleTimeout)