v4 architecture: pipeline stages, SDK, event bus, LLM-driven memory consolidation

- SDK PluginAPI (internal/plugin/sdk/): RegisterTool/RegisterStage/Subscribe/Publish
- EventBus (internal/events/): system-level pub/sub with wildcard support
- StageHost (internal/agent/core/stages.go): 7-stage message pipeline
- Agent core: on_input/pre_action/post_action/before_toolcall/after_toolcall/before_output/after_output
- Plugin Registry: SDK plugin registration and tool routing
- GraphDB.MergeEntities: entity consolidation with relation redirection
- memory_merge tool: allows LLM to merge similar entities
- Consolidation task: heartbeat detects conflicts, enqueues via IO for LLM decision
- _consolidation_ internal channel for system-level memory maintenance
- Comprehensive documentation: ARCHITECTURE.md, PLAN.md, DESIGN.md, README.md
- 54 tests across all packages, all passing

internal/api/plugin.go

@@ -0,0 +1,68 @@
+package api
+
+import (
+	"log"
+	"net/http"
+
+	agentIO "gitcode.com/JianFeeeee/HomeAgent/internal/agent/io"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/knowledge"
+	luaVM "gitcode.com/JianFeeeee/HomeAgent/internal/lua"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/memory"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/memory/text"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/skill"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/supervisor"
+	"gitcode.com/JianFeeeee/HomeAgent/internal/tracker"
+	"gitcode.com/JianFeeeee/HomeAgent/pkg/types"
+)
+
+// Plugin 将 HTTP API + WebUI 包装为 IO Device
+// 作为 HomeAgent 自带的默认 IO 通道插件
+type Plugin struct {
+	name    string
+	handler *Handler
+	server  *http.Server
+	addr    string
+	mux     *http.ServeMux
+}
+
+func NewWebUIPlugin(name, addr string, sup *supervisor.Daemon, mem *memory.GraphDB, sk *skill.Manager,
+	lua *luaVM.VM, cfg *types.Config, iom *agentIO.IOManager, tm *text.Memory, ks *knowledge.Store, tr *tracker.Tracker) *Plugin {
+
+	h := NewHandler(sup, mem, sk, lua, cfg, iom, tm, ks, tr)
+	mux := http.NewServeMux()
+	h.RegisterRoutes(mux)
+
+	return &Plugin{
+		name:    name,
+		handler: h,
+		addr:    addr,
+		mux:     mux,
+	}
+}
+
+func (p *Plugin) Name() string                           { return p.name }
+func (p *Plugin) Type() agentIO.DeviceType               { return agentIO.DeviceIO }
+func (p *Plugin) Description() string                    { return "HTTP API & Web Dashboard" }
+func (p *Plugin) OutputCapabilities() agentIO.OutputCapability { return agentIO.CapText | agentIO.CapStructured }
+func (p *Plugin) Tools() []agentIO.ToolDef                { return nil }
+func (p *Plugin) Execute(tool string, args map[string]interface{}) (interface{}, error) {
+	return nil, nil
+}
+
+func (p *Plugin) Start() error {
+	p.server = &http.Server{Addr: p.addr, Handler: p.mux}
+	go func() {
+		log.Printf("[webui] HTTP server listening on %s", p.addr)
+		if err := p.server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			log.Printf("[webui] server error: %v", err)
+		}
+	}()
+	return nil
+}
+
+func (p *Plugin) Stop() error {
+	if p.server != nil {
+		return p.server.Close()
+	}
+	return nil
+}