feat: output channel redesign - per-channel output gates, LLM chain events, SDKConfig

- Output channels generate per-channel tools: output_send__{name} (type=output) + output_send__{name}_help
- content is JSON string transparently passed to plugin handler for routing
- EventAgentLLMChain: full LLM response forwarded after each turn for webui/logs
- sdk.New refactored to SDKConfig struct (no more 13 positional args)
- RegisterOutputChannel adds desc param for JSON format documentation
- channelDevice simplified (no Tools method), desc field added
- Child agent permission updated for output_send__ prefix
- System prompt: output gates, multi-call, long messages split
- WebUI: subscribes to EventAgentLLMChain in SSE, no output channel
- Tests updated for new naming convention

internal/plugins/webui/plugin.go

@@ -155,11 +155,30 @@ func (p *Plugin) ensureAuthBootstrap(s *sdk.PluginSDK) {
 func (p *Plugin) Name() string { return p.name }
 
 func (p *Plugin) Start(s *sdk.PluginSDK) error {
+	s.SetAutoRestart(true)
 	s.Settings().RegisterDef(sdk.ConfigDef{Key: "api_key", Default: "", Type: "password", DisplayName: "API 密钥", Description: "访问 API 时需要的密钥", Category: "webui"})
 	s.Settings().RegisterDef(sdk.ConfigDef{Key: "username", Default: "admin", Type: "string", DisplayName: "登录用户名", Description: "Web 控制台登录用户名", Category: "webui"})
 	s.Settings().RegisterDef(sdk.ConfigDef{Key: "password", Default: "", Type: "password", DisplayName: "Web 控制台登录密码", Description: "Web 控制台登录密码", Category: "webui"})
 	s.Settings().RegisterDef(sdk.ConfigDef{Key: "session_ttl_hours", Default: "24", Type: "int", DisplayName: "会话时长(小时)", Description: "登录 cookie 有效时长", Category: "webui"})
 	p.ensureAuthBootstrap(s)
+
+	s.RegisterStage(sdk.StagePreAction, func(ctx *sdk.StageContext) error {
+		p.evBus.Publish(&events.Event{Type: events.EventStage, Payload: map[string]interface{}{"phase": "pre_action", "message": "thinking"}})
+		return nil
+	})
+	s.RegisterStage(sdk.StageBeforeToolcall, func(ctx *sdk.StageContext) error {
+		tool := ""
+		if len(ctx.ToolCalls) > 0 {
+			tool = ctx.ToolCalls[0].Name
+		}
+		p.evBus.Publish(&events.Event{Type: events.EventStage, Payload: map[string]interface{}{"phase": "before_toolcall", "tool": tool, "message": "tool:" + tool}})
+		return nil
+	})
+	s.RegisterStage(sdk.StageBeforeOutput, func(ctx *sdk.StageContext) error {
+		p.evBus.Publish(&events.Event{Type: events.EventStage, Payload: map[string]interface{}{"phase": "before_output", "message": "output"}})
+		return nil
+	})
+
 	h := NewHandler(p.sup, p.mem, p.sk, p.lua, p.cfg, p.iom, p.tm, p.ks, p.tr, p.cr, p.pr, p.evBus, p.statusProvider, p.providerMgr, p.baseAPIKey)
 	p.handler = h
 	h.RegisterRoutes(p.mux)