webui: 修复 '删除源/服务器' 只置 <nil> 不真删的问题

前端 deleteSource/deleteMCPServer 通过 PUT value:null 删除，但后端 handleSettings
PUT 只 SetCore/SetPlugin（fmt.Sprint(nil) → 字面 '<nil>'），导致 core.llm.sources.<name>.*
等键残留不可达的 <nil> 行，污染 LLM 源与探活。

- SettingsAPI 新增 RemoveCore/RemovePlugin；settingsImpl 接入 ConfigRegistry.Delete
- webui handleSettings PUT：body.Value==null 时改走删除分支（核心表/插件表均适配）
- 现状验证：mocktest.* 残留已从本机 config.db 清除，sources=3，无无效源

internal/plugins/webui/handler.go

@@ -49,8 +49,8 @@ type Handler struct {
 	status     sdk.StatusAPI
 	llm        sdk.LLMAPI
 
-	sessionMu  sync.Mutex
-	sessions   map[string]time.Time
+	sessionMu sync.Mutex
+	sessions  map[string]time.Time
 
 	chatMu      sync.Mutex
 	chatHistory []ChatMsg
@@ -282,12 +282,18 @@ func (h *Handler) getWebUIConfig() (apiKey, username, password string, ttl time.
 	if v, _ := h.settings.Get("session_ttl_hours"); v != nil {
 		switch n := v.(type) {
 		case float64:
-			if n > 0 { ttl = time.Duration(n) * time.Hour }
+			if n > 0 {
+				ttl = time.Duration(n) * time.Hour
+			}
 		case string:
-			if i, err := strconv.Atoi(n); err == nil && i > 0 { ttl = time.Duration(i) * time.Hour }
+			if i, err := strconv.Atoi(n); err == nil && i > 0 {
+				ttl = time.Duration(i) * time.Hour
+			}
 		}
 	}
-	if username == "" { username = "admin" }
+	if username == "" {
+		username = "admin"
+	}
 	return
 }
 
@@ -426,7 +432,10 @@ func (h *Handler) handleLogin(w http.ResponseWriter, r *http.Request) {
 		writeJSON(w, http.StatusServiceUnavailable, map[string]string{"error": "webui username/password not configured"})
 		return
 	}
-	var body struct { Username string `json:"username"`; Password string `json:"password"` }
+	var body struct {
+		Username string `json:"username"`
+		Password string `json:"password"`
+	}
 	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
 		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request"})
 		return
@@ -1156,16 +1165,29 @@ func (h *Handler) handleSettings(w http.ResponseWriter, r *http.Request) {
 			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request"})
 			return
 		}
+		deleting := body.Value == nil
 		if strings.HasPrefix(body.Key, "plugin.") {
 			parts := strings.SplitN(body.Key, ".", 3)
 			if len(parts) >= 3 {
-				if err := h.settings.SetPlugin(parts[1], parts[2], body.Value); err != nil {
+				var err error
+				if deleting {
+					err = h.settings.RemovePlugin(parts[1], parts[2])
+				} else {
+					err = h.settings.SetPlugin(parts[1], parts[2], body.Value)
+				}
+				if err != nil {
 					writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
 					return
 				}
 			}
 		} else {
-			if err := h.settings.SetCore(body.Key, body.Value); err != nil {
+			var err error
+			if deleting {
+				err = h.settings.RemoveCore(body.Key)
+			} else {
+				err = h.settings.SetCore(body.Key, body.Value)
+			}
+			if err != nil {
 				writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
 				return
 			}
@@ -1320,8 +1342,8 @@ func (h *Handler) writeOpenAIStream(w http.ResponseWriter, model, content, reaso
 		"model":   model,
 		"choices": []map[string]interface{}{
 			{
-				"index": 0,
-				"delta": map[string]interface{}{},
+				"index":         0,
+				"delta":         map[string]interface{}{},
 				"finish_reason": "stop",
 			},
 		},

internal/sdk/settings.go

@@ -11,6 +11,10 @@ type SettingsAPI interface {
 	DefsPlugin(plugin, prefix string) []*ConfigDef
 	// Remove 删除本插件配置中的单个键（插件删除时清理自身配置用）。
 	Remove(key string) error
+	// RemoveCore 删除核心配置表中的单个键。
+	RemoveCore(key string) error
+	// RemovePlugin 删除另一个插件配置表中的单个键。
+	RemovePlugin(plugin, key string) error
 }
 
 type ConfigDef = pubsdk.ConfigDef

internal/sdk/settings_impl.go

@@ -17,19 +17,33 @@ func NewSettings(name string, reg *internalConfig.ConfigRegistry) SettingsAPI {
 }
 
 func (s *settingsImpl) Get(key string) (interface{}, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	return s.reg.PluginConfig(s.pluginName).Get(key)
 }
 func (s *settingsImpl) Set(key string, value interface{}) error {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return s.reg.PluginConfig(s.pluginName).Set(key, value)
 }
 func (s *settingsImpl) Remove(key string) error {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return s.reg.PluginConfig(s.pluginName).Remove(key)
 }
+func (s *settingsImpl) RemoveCore(key string) error {
+	if s.reg == nil {
+		return nil
+	}
+	return s.reg.Delete(coreKey(key))
+}
 func (s *settingsImpl) List(prefix string) ([]string, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	return s.reg.PluginConfig(s.pluginName).List(prefix)
 }
 func coreKey(key string) string {
@@ -40,15 +54,21 @@ func coreKey(key string) string {
 }
 
 func (s *settingsImpl) GetCore(key string) (interface{}, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	return s.reg.Get(coreKey(key))
 }
 func (s *settingsImpl) SetCore(key string, value interface{}) error {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return s.reg.Set(coreKey(key), value)
 }
 func (s *settingsImpl) ListCore(prefix string) ([]string, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	p := coreKey(prefix)
 	if p == "core." {
 		p = "core."
@@ -56,19 +76,33 @@ func (s *settingsImpl) ListCore(prefix string) ([]string, error) {
 	return s.reg.List(p), nil
 }
 func (s *settingsImpl) GetPlugin(plugin, key string) (interface{}, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	return s.reg.PluginConfig(plugin).Get(key)
 }
 func (s *settingsImpl) SetPlugin(plugin, key string, value interface{}) error {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return s.reg.PluginConfig(plugin).Set(key, value)
 }
+func (s *settingsImpl) RemovePlugin(plugin, key string) error {
+	if s.reg == nil {
+		return nil
+	}
+	return s.reg.PluginConfig(plugin).Remove(key)
+}
 func (s *settingsImpl) ListPlugin(plugin, prefix string) ([]string, error) {
-	if s.reg == nil { return nil, nil }
+	if s.reg == nil {
+		return nil, nil
+	}
 	return s.reg.PluginConfig(plugin).List(prefix)
 }
 func (s *settingsImpl) RegisterDef(def ConfigDef) {
-	if s.reg == nil { return }
+	if s.reg == nil {
+		return
+	}
 	s.reg.PluginConfig(s.pluginName).RegisterDef(internalConfig.ConfigDef{
 		Key: def.Key, Type: def.Type, DisplayName: def.DisplayName, Description: def.Description,
 		Category: def.Category, Options: def.Options,
@@ -76,7 +110,9 @@ func (s *settingsImpl) RegisterDef(def ConfigDef) {
 	})
 }
 func (s *settingsImpl) Defs(prefix string) []*ConfigDef {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	defs := s.reg.PluginConfig(s.pluginName).ListDefs(prefix)
 	out := make([]*ConfigDef, len(defs))
 	for i, d := range defs {
@@ -90,11 +126,15 @@ func (s *settingsImpl) Defs(prefix string) []*ConfigDef {
 	return out
 }
 func (s *settingsImpl) Dump() map[string]interface{} {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return s.reg.Dump()
 }
 func (s *settingsImpl) Plugins() []string {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	names := s.reg.ListPlugins()
 	result := make([]string, 0, len(names)+1)
 	result = append(result, "core")
@@ -102,11 +142,15 @@ func (s *settingsImpl) Plugins() []string {
 	return result
 }
 func (s *settingsImpl) DefsCore(prefix string) []*ConfigDef {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return mapDefs(s.reg.ListDefs(prefix))
 }
 func (s *settingsImpl) DefsPlugin(plugin, prefix string) []*ConfigDef {
-	if s.reg == nil { return nil }
+	if s.reg == nil {
+		return nil
+	}
 	return mapDefs(s.reg.PluginConfig(plugin).ListDefs(prefix))
 }
 
@@ -122,13 +166,19 @@ func mapDefs(defs []*internalConfig.ConfigDef) []*ConfigDef {
 }
 
 func stringifyDefault(v interface{}) string {
-	if v == nil { return "" }
+	if v == nil {
+		return ""
+	}
 	switch x := v.(type) {
-	case string: return x
+	case string:
+		return x
 	case bool:
-		if x { return "true" }
+		if x {
+			return "true"
+		}
 		return "false"
-	default: return fmt.Sprint(v)
+	default:
+		return fmt.Sprint(v)
 	}
 }