feat: RAG, memory, plugins, lessons, file editor, split panes, Markdown rendering, PWA + UI overhaul

Major additions:
- RAG pipeline (indexing, chunking, search) with sidebar upload button
- Memory system with CRUD API
- Plugins and lessons modules
- MCP discovery and MCP server
- Advanced skills (auto-create, conditional, improver)
- Agent browser/image support, delegate, sessions
- File editor with CodeMirror in split panes
- Markdown rendering via react-markdown + KaTeX + highlight.js
- Raw markdown toggle
- PWA manifest + service worker
- Extension UI redesign with new design tokens and studio-style chat
- Pipeline API for chat streaming
- Mobile responsive layout

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/plugins/hooks.go

@@ -0,0 +1,94 @@
+package plugins
+
+import (
+	"context"
+	"encoding/json"
+	"sync"
+
+	"github.com/muyue/muyue/internal/agent"
+)
+
+type HookType string
+
+const (
+	BeforeToolCall      HookType = "before_tool_call"
+	AfterToolCall       HookType = "after_tool_call"
+	OnConversationStart HookType = "on_conversation_start"
+	OnToolError         HookType = "on_tool_error"
+)
+
+type HookFunc func(ctx context.Context, payload HookPayload) error
+
+type HookPayload struct {
+	ToolName  string                 `json:"tool_name"`
+	Arguments json.RawMessage        `json:"arguments,omitempty"`
+	Response  *agent.ToolResponse    `json:"response,omitempty"`
+	Error     string                 `json:"error,omitempty"`
+	Metadata  map[string]interface{} `json:"metadata,omitempty"`
+}
+
+type Hook struct {
+	Type     HookType
+	Plugin   string
+	Priority int
+	Fn       HookFunc
+}
+
+type HookRegistry struct {
+	mu    sync.RWMutex
+	hooks map[HookType][]Hook
+}
+
+func NewHookRegistry() *HookRegistry {
+	return &HookRegistry{
+		hooks: make(map[HookType][]Hook),
+	}
+}
+
+func (hr *HookRegistry) Register(hookType HookType, pluginName string, priority int, fn HookFunc) {
+	hr.mu.Lock()
+	defer hr.mu.Unlock()
+
+	h := Hook{
+		Type:     hookType,
+		Plugin:   pluginName,
+		Priority: priority,
+		Fn:       fn,
+	}
+	hr.hooks[hookType] = append(hr.hooks[hookType], h)
+
+	for i := len(hr.hooks[hookType]) - 1; i > 0; i-- {
+		if hr.hooks[hookType][i].Priority < hr.hooks[hookType][i-1].Priority {
+			hr.hooks[hookType][i], hr.hooks[hookType][i-1] = hr.hooks[hookType][i-1], hr.hooks[hookType][i]
+		}
+	}
+}
+
+func (hr *HookRegistry) Fire(ctx context.Context, hookType HookType, payload HookPayload) error {
+	hr.mu.RLock()
+	hooks := make([]Hook, len(hr.hooks[hookType]))
+	copy(hooks, hr.hooks[hookType])
+	hr.mu.RUnlock()
+
+	for _, h := range hooks {
+		if err := h.Fn(ctx, payload); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (hr *HookRegistry) RemoveByPlugin(pluginName string) {
+	hr.mu.Lock()
+	defer hr.mu.Unlock()
+
+	for hookType := range hr.hooks {
+		filtered := make([]Hook, 0, len(hr.hooks[hookType]))
+		for _, h := range hr.hooks[hookType] {
+			if h.Plugin != pluginName {
+				filtered = append(filtered, h)
+			}
+		}
+		hr.hooks[hookType] = filtered
+	}
+}