fix(config): persist disabled placeholder settings (#1902)

pkg/config/config.go

@@ -381,7 +381,7 @@ type TypingConfig struct {
 
 // PlaceholderConfig controls placeholder message behavior (Phase 10).
 type PlaceholderConfig struct {
-	Enabled bool   `json:"enabled,omitempty"`
+	Enabled bool   `json:"enabled"`
 	Text    string `json:"text,omitempty"`
 }
 

pkg/config/config_test.go

@@ -360,6 +360,37 @@ func TestSaveConfig_IncludesEmptyLegacyModelField(t *testing.T) {
 	}
 }
 
+func TestSaveConfig_PreservesDisabledTelegramPlaceholder(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "config.json")
+
+	cfg := DefaultConfig()
+	cfg.Channels.Telegram.Placeholder.Enabled = false
+
+	if err := SaveConfig(path, cfg); err != nil {
+		t.Fatalf("SaveConfig failed: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("ReadFile failed: %v", err)
+	}
+	if !strings.Contains(string(data), `"placeholder": {`) {
+		t.Fatalf("saved config should include telegram placeholder config, got: %s", string(data))
+	}
+	if !strings.Contains(string(data), `"enabled": false`) {
+		t.Fatalf("saved config should persist placeholder.enabled=false, got: %s", string(data))
+	}
+
+	loaded, err := LoadConfig(path)
+	if err != nil {
+		t.Fatalf("LoadConfig failed: %v", err)
+	}
+	if loaded.Channels.Telegram.Placeholder.Enabled {
+		t.Fatal("telegram placeholder should remain disabled after SaveConfig/LoadConfig round-trip")
+	}
+}
+
 // TestConfig_Complete verifies all config fields are set
 func TestConfig_Complete(t *testing.T) {
 	cfg := DefaultConfig()