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+# 🔌 Plugin Specification - Extension Development Guide
+
+## Philosophy: Everything is a Plugin
+
+**Core Principle:** If core features (Chat, Channels, Notes) are implemented as plugins, we prove that ANY feature can be a plugin.
+
+```
+Minimal Core (Go)          Extensions (Any Language)
+├── HTTP Router            ├── Chat Engine (Python)
+├── WebSocket Hub          ├── Channels (Go)
+├── Extension Manager      ├── RAG Engine (Python)
+├── Auth/Users             ├── Workflows (Go + Python)
+└── PostgreSQL             └── Your Custom Plugin...
+```
+
+## Plugin Types
+
+### 1. Frontend Plugins (UI Only)
+**Language:** JavaScript  
+**Runs:** In browser  
+**Capabilities:** UI modifications, client-side logic  
+**Modes:** Both managed and unmanaged
+
+### 2. Backend Plugins (Full Power)
+**Language:** Python, Go, Node.js, Rust, etc.  
+**Runs:** As separate process  
+**Capabilities:** Tools, models, data processing, external APIs  
+**Modes:** Managed only
+
+## Frontend Plugin API
+
+### Plugin Structure
+
+```
+extensions/frontend/token-counter/
+├── manifest.json          # Plugin metadata
+├── main.js               # Entry point
+├── styles.css            # Optional styles
+└── README.md
+```
+
+### manifest.json
+
+```json
+{
+  "name": "token-counter",
+  "version": "1.0.0",
+  "author": "Your Name",
+  "description": "Display token count for messages",
+  "type": "frontend",
+  "entry": "main.js",
+  "permissions": [
+    "message:read",
+    "ui:inject"
+  ],
+  "hooks": [
+    "onMessageSend",
+    "onMessageReceive",
+    "onUIRender"
+  ]
+}
+```
+
+### main.js Example
+
+```javascript
+// Frontend plugin template
+(function() {
+  'use strict';
+  
+  // Plugin initialization
+  window.ChatSwitchboard = window.ChatSwitchboard || {};
+  window.ChatSwitchboard.plugins = window.ChatSwitchboard.plugins || [];
+  
+  const TokenCounter = {
+    name: 'token-counter',
+    version: '1.0.0',
+    
+    // Called when plugin loads
+    init: function() {
+      console.log('Token Counter plugin loaded');
+      this.addUI();
+    },
+    
+    // Hook: Before message is sent
+    hooks: {
+      onMessageSend: function(message) {
+        const tokens = this.estimateTokens(message.content);
+        console.log(`Message has ~${tokens} tokens`);
+        
+        // Show warning if too long
+        if (tokens > 4000) {
+          window.ChatSwitchboard.showToast(
+            `⚠️ Long message: ${tokens} tokens`,
+            'warning'
+          );
+        }
+        
+        // Can modify message before sending
+        return message;
+      },
+      
+      onMessageReceive: function(message) {
+        // Process incoming messages
+        return message;
+      },
+      
+      onUIRender: function() {
+        // Inject UI elements
+        this.updateTokenDisplay();
+      }
+    },
+    
+    // Add token counter to UI
+    addUI: function() {
+      const inputArea = document.querySelector('.input-area');
+      const counter = document.createElement('div');
+      counter.id = 'token-counter';
+      counter.className = 'plugin-token-counter';
+      counter.textContent = '0 tokens';
+      inputArea.appendChild(counter);
+      
+      // Update on input
+      const textarea = document.getElementById('messageInput');
+      textarea.addEventListener('input', () => {
+        const tokens = this.estimateTokens(textarea.value);
+        counter.textContent = `${tokens} tokens`;
+      });
+    },
+    
+    // Token estimation (rough approximation)
+    estimateTokens: function(text) {
+      return Math.ceil(text.length / 4);
+    },
+    
+    updateTokenDisplay: function() {
+      const counter = document.getElementById('token-counter');
+      const input = document.getElementById('messageInput');
+      if (counter && input) {
+        const tokens = this.estimateTokens(input.value);
+        counter.textContent = `${tokens} tokens`;
+      }
+    }
+  };
+  
+  // Register plugin
+  window.ChatSwitchboard.plugins.push(TokenCounter);
+  
+  // Auto-init when DOM ready
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', () => TokenCounter.init());
+  } else {
+    TokenCounter.init();
+  }
+})();
+```
+
+### Available Hooks
+
+```javascript
+// Message lifecycle
+onMessageSend(message)           // Before sending to API
+onMessageReceive(message)        // After receiving from API
+onMessageRender(element, message) // When rendering to DOM
+
+// UI lifecycle
+onUIRender()                     // After UI updates
+onChatSwitch(chatId)             // When switching chats
+onModelChange(model)             // When model changes
+
+// Extension points
+onToolCall(tool, params)         // Before calling tool
+onToolResult(tool, result)       // After tool returns
+
+// Settings
+onSettingsOpen()                 // Settings modal opened
+onSettingsSave(settings)         // Settings saved
+
+// Files
+onFileUpload(file)               // File uploaded
+onFileSelect(file)               // File selected for chat
+```
+
+### Plugin API Methods
+
+```javascript
+// Toast notifications
+ChatSwitchboard.showToast(message, type); // type: success, error, warning, info
+
+// Storage (scoped to plugin)
+ChatSwitchboard.storage.set(key, value);
+ChatSwitchboard.storage.get(key);
+ChatSwitchboard.storage.remove(key);
+
+// UI manipulation
+ChatSwitchboard.ui.addButton(location, config);
+ChatSwitchboard.ui.addPanel(config);
+ChatSwitchboard.ui.addMenuItem(config);
+
+// State access (read-only)
+ChatSwitchboard.state.getCurrentChat();
+ChatSwitchboard.state.getCurrentModel();
+ChatSwitchboard.state.getSettings();
+
+// Events
+ChatSwitchboard.events.on(event, callback);
+ChatSwitchboard.events.off(event, callback);
+ChatSwitchboard.events.emit(event, data);
+```
+
+## Backend Plugin API
+
+### Plugin Structure
+
+```
+extensions/backend/web-search/
+├── extension.json        # Manifest
+├── main.py              # Entry point (or main.go, server.js, etc)
+├── requirements.txt     # Dependencies (Python)
+├── config.yaml          # Configuration
+└── README.md
+```
+
+### extension.json
+
+```json
+{
+  "name": "web-search",
+  "version": "1.0.0",
+  "author": "Chat Switchboard Team",
+  "description": "Search the web using DuckDuckGo API",
+  "type": "backend",
+  "runtime": "python",
+  "entry": "main.py",
+  "port": 9001,
+  "capabilities": ["tool"],
+  "dependencies": {
+    "python": ">=3.9",
+    "packages": ["fastapi", "uvicorn", "duckduckgo-search"]
+  },
+  "tools": [
+    {
+      "name": "search_web",
+      "description": "Search the web for information",
+      "parameters": {
+        "type": "object",
+        "properties": {
+          "query": {
+            "type": "string",
+            "description": "Search query"
+          },
+          "max_results": {
+            "type": "integer",
+            "description": "Maximum results to return",
+            "default": 5
+          }
+        },
+        "required": ["query"]
+      },
+      "returns": {
+        "type": "object",
+        "properties": {
+          "results": {
+            "type": "array",
+            "items": {
+              "type": "object",
+              "properties": {
+                "title": {"type": "string"},
+                "url": {"type": "string"},
+                "snippet": {"type": "string"}
+              }
+            }
+          }
+        }
+      }
+    }
+  ],
+  "config": {
+    "max_requests_per_minute": 30,
+    "timeout_seconds": 10
+  }
+}
+```
+
+### Python Plugin Template
+
+```python
+# extensions/backend/web-search/main.py
+from fastapi import FastAPI, HTTPException
+from pydantic import BaseModel
+from duckduckgo_search import DDGS
+import uvicorn
+import os
+
+app = FastAPI(title="Web Search Plugin")
+
+# Load config
+PORT = int(os.getenv("PLUGIN_PORT", 9001))
+MAX_RESULTS = int(os.getenv("MAX_RESULTS", 5))
+
+# Request/response models
+class SearchRequest(BaseModel):
+    query: str
+    max_results: int = 5
+
+class SearchResult(BaseModel):
+    title: str
+    url: str
+    snippet: str
+
+class SearchResponse(BaseModel):
+    results: list[SearchResult]
+
+# Tool endpoint
+@app.post("/tools/search_web", response_model=SearchResponse)
+async def search_web(request: SearchRequest):
+    """Search the web using DuckDuckGo"""
+    try:
+        ddgs = DDGS()
+        results = ddgs.text(
+            request.query,
+            max_results=min(request.max_results, MAX_RESULTS)
+        )
+        
+        return SearchResponse(
+            results=[
+                SearchResult(
+                    title=r.get("title", ""),
+                    url=r.get("href", ""),
+                    snippet=r.get("body", "")
+                )
+                for r in results
+            ]
+        )
+    except Exception as e:
+        raise HTTPException(status_code=500, detail=str(e))
+
+# Health check
+@app.get("/health")
+async def health():
+    return {"status": "ok", "plugin": "web-search"}
+
+# Plugin info
+@app.get("/info")
+async def info():
+    return {
+        "name": "web-search",
+        "version": "1.0.0",
+        "tools": ["search_web"]
+    }
+
+if __name__ == "__main__":
+    uvicorn.run(app, host="127.0.0.1", port=PORT)
+```
+
+### Go Plugin Template
+
+```go
+// extensions/backend/file-ops/main.go
+package main
+
+import (
+    "github.com/gin-gonic/gin"
+    "os"
+    "io/ioutil"
+)
+
+type ReadFileRequest struct {
+    Path string `json:"path" binding:"required"`
+}
+
+type ReadFileResponse struct {
+    Content string `json:"content"`
+    Size    int64  `json:"size"`
+}
+
+func main() {
+    r := gin.Default()
+    
+    // Tool endpoint
+    r.POST("/tools/read_file", func(c *gin.Context) {
+        var req ReadFileRequest
+        if err := c.ShouldBindJSON(&req); err != nil {
+            c.JSON(400, gin.H{"error": err.Error()})
+            return
+        }
+        
+        content, err := ioutil.ReadFile(req.Path)
+        if err != nil {
+            c.JSON(500, gin.H{"error": err.Error()})
+            return
+        }
+        
+        info, _ := os.Stat(req.Path)
+        
+        c.JSON(200, ReadFileResponse{
+            Content: string(content),
+            Size:    info.Size(),
+        })
+    })
+    
+    // Health check
+    r.GET("/health", func(c *gin.Context) {
+        c.JSON(200, gin.H{"status": "ok"})
+    })
+    
+    // Start server
+    port := os.Getenv("PLUGIN_PORT")
+    if port == "" {
+        port = "9002"
+    }
+    r.Run(":" + port)
+}
+```
+
+## Extension Manager (Backend Core)
+
+### Go Extension Manager
+
+```go
+// server/extensions/manager.go
+package extensions
+
+import (
+    "encoding/json"
+    "fmt"
+    "io/ioutil"
+    "os"
+    "os/exec"
+    "path/filepath"
+    "sync"
+)
+
+type Extension struct {
+    Name      string                 `json:"name"`
+    Version   string                 `json:"version"`
+    Runtime   string                 `json:"runtime"`
+    Entry     string                 `json:"entry"`
+    Port      int                    `json:"port"`
+    Tools     []Tool                 `json:"tools"`
+    Process   *os.Process
+    BaseURL   string
+}
+
+type Tool struct {
+    Name        string                 `json:"name"`
+    Description string                 `json:"description"`
+    Parameters  map[string]interface{} `json:"parameters"`
+}
+
+type Manager struct {
+    extensions map[string]*Extension
+    tools      map[string]*Tool
+    mu         sync.RWMutex
+}
+
+func NewManager() *Manager {
+    return &Manager{
+        extensions: make(map[string]*Extension),
+        tools:      make(map[string]*Tool),
+    }
+}
+
+// Load all extensions from directory
+func (m *Manager) LoadExtensions(dir string) error {
+    entries, err := ioutil.ReadDir(dir)
+    if err != nil {
+        return err
+    }
+    
+    for _, entry := range entries {
+        if !entry.IsDir() {
+            continue
+        }
+        
+        extPath := filepath.Join(dir, entry.Name())
+        if err := m.LoadExtension(extPath); err != nil {
+            log.Printf("Failed to load extension %s: %v", entry.Name(), err)
+        }
+    }
+    
+    return nil
+}
+
+// Load single extension
+func (m *Manager) LoadExtension(path string) error {
+    // Read manifest
+    manifestPath := filepath.Join(path, "extension.json")
+    data, err := ioutil.ReadFile(manifestPath)
+    if err != nil {
+        return err
+    }
+    
+    var ext Extension
+    if err := json.Unmarshal(data, &ext); err != nil {
+        return err
+    }
+    
+    // Start extension process
+    if err := m.startExtension(&ext, path); err != nil {
+        return err
+    }
+    
+    // Register tools
+    for i := range ext.Tools {
+        ext.Tools[i].ExtensionName = ext.Name
+        m.tools[ext.Tools[i].Name] = &ext.Tools[i]
+    }
+    
+    m.mu.Lock()
+    m.extensions[ext.Name] = &ext
+    m.mu.Unlock()
+    
+    log.Printf("✅ Loaded extension: %s v%s", ext.Name, ext.Version)
+    return nil
+}
+
+// Start extension process
+func (m *Manager) startExtension(ext *Extension, path string) error {
+    var cmd *exec.Cmd
+    
+    switch ext.Runtime {
+    case "python":
+        cmd = exec.Command("python3", ext.Entry)
+    case "go":
+        cmd = exec.Command("go", "run", ext.Entry)
+    case "node":
+        cmd = exec.Command("node", ext.Entry)
+    default:
+        return fmt.Errorf("unsupported runtime: %s", ext.Runtime)
+    }
+    
+    cmd.Dir = path
+    cmd.Env = append(os.Environ(), fmt.Sprintf("PLUGIN_PORT=%d", ext.Port))
+    
+    if err := cmd.Start(); err != nil {
+        return err
+    }
+    
+    ext.Process = cmd.Process
+    ext.BaseURL = fmt.Sprintf("http://localhost:%d", ext.Port)
+    
+    // Wait for extension to be ready
+    time.Sleep(2 * time.Second)
+    
+    return nil
+}
+
+// Call tool
+func (m *Manager) CallTool(name string, params map[string]interface{}) (interface{}, error) {
+    m.mu.RLock()
+    tool, exists := m.tools[name]
+    m.mu.RUnlock()
+    
+    if !exists {
+        return nil, fmt.Errorf("tool not found: %s", name)
+    }
+    
+    ext := m.extensions[tool.ExtensionName]
+    url := fmt.Sprintf("%s/tools/%s", ext.BaseURL, name)
+    
+    // HTTP POST to extension
+    body, _ := json.Marshal(params)
+    resp, err := http.Post(url, "application/json", bytes.NewBuffer(body))
+    if err != nil {
+        return nil, err
+    }
+    defer resp.Body.Close()
+    
+    var result interface{}
+    json.NewDecoder(resp.Body).Decode(&result)
+    return result, nil
+}
+
+// List all tools
+func (m *Manager) ListTools() []Tool {
+    m.mu.RLock()
+    defer m.mu.RUnlock()
+    
+    tools := make([]Tool, 0, len(m.tools))
+    for _, tool := range m.tools {
+        tools = append(tools, *tool)
+    }
+    return tools
+}
+
+// Shutdown all extensions
+func (m *Manager) Shutdown() {
+    m.mu.Lock()
+    defer m.mu.Unlock()
+    
+    for _, ext := range m.extensions {
+        if ext.Process != nil {
+            ext.Process.Kill()
+        }
+    }
+}
+```
+
+### Extension Discovery
+
+```go
+// server/main.go
+func main() {
+    // ... existing setup ...
+    
+    // Load extensions
+    extManager := extensions.NewManager()
+    if err := extManager.LoadExtensions("./extensions/backend"); err != nil {
+        log.Fatal("Failed to load extensions:", err)
+    }
+    defer extManager.Shutdown()
+    
+    // Expose extension tools via API
+    r.GET("/api/tools", func(c *gin.Context) {
+        tools := extManager.ListTools()
+        c.JSON(200, tools)
+    })
+    
+    r.POST("/api/tools/:name", func(c *gin.Context) {
+        toolName := c.Param("name")
+        var params map[string]interface{}
+        c.BindJSON(&params)
+        
+        result, err := extManager.CallTool(toolName, params)
+        if err != nil {
+            c.JSON(500, gin.H{"error": err.Error()})
+            return
+        }
+        c.JSON(200, result)
+    })
+}
+```
+
+## Plugin Development Workflow
+
+### 1. Create from Template
+
+```bash
+# Frontend plugin
+cp -r extensions/frontend/_template extensions/frontend/my-plugin
+cd extensions/frontend/my-plugin
+# Edit manifest.json, main.js
+
+# Backend plugin (Python)
+cp -r extensions/backend/_template-python extensions/backend/my-plugin
+cd extensions/backend/my-plugin
+# Edit extension.json, main.py
+pip install -r requirements.txt
+```
+
+### 2. Test Locally
+
+```bash
+# Backend plugin
+python main.py  # Runs on port from extension.json
+
+# Test tool
+curl -X POST http://localhost:9001/tools/my_tool \
+  -H "Content-Type: application/json" \
+  -d '{"param": "value"}'
+```
+
+### 3. Install in Chat Switchboard
+
+```bash
+# Move to extensions directory
+mv my-plugin ../chat-switchboard/extensions/backend/
+
+# Restart backend
+cd ../chat-switchboard
+docker-compose restart backend
+```
+
+### 4. Publish to Marketplace
+
+```bash
+# Package extension
+tar -czf my-plugin-1.0.0.tar.gz my-plugin/
+
+# Upload to marketplace
+curl -X POST https://marketplace.chatswitch.io/api/publish \
+  -F "file=@my-plugin-1.0.0.tar.gz" \
+  -F "category=tools" \
+  -H "Authorization: Bearer $TOKEN"
+```
+
+## Security & Sandboxing
+
+### Backend Plugin Isolation
+
+```yaml
+# docker-compose.yml - Run plugins in containers
+services:
+  plugin-web-search:
+    build: ./extensions/backend/web-search
+    ports:
+      - "9001:9001"
+    environment:
+      - PLUGIN_PORT=9001
+    networks:
+      - extension-network
+    restart: always
+```
+
+### Permission System
+
+```json
+// Plugins declare required permissions
+{
+  "permissions": [
+    "network:outbound",     // Make external HTTP requests
+    "storage:read",         // Read from DB
+    "storage:write",        // Write to DB
+    "file:read",           // Read files
+    "tool:call:*"          // Call other tools
+  ]
+}
+```
+
+## Official Plugin List
+
+### Bundled with Core
+
+1. **chat-engine** (Python) - LLM conversation handling
+2. **channels** (Go) - Multi-user chat rooms
+3. **rag-engine** (Python) - Vector search, embeddings
+4. **workflows** (Go/Python) - Workflow orchestration
+5. **notes** (Go) - Note management
+
+### Official Extensions
+
+6. **web-search** (Python) - DuckDuckGo search
+7. **code-runner** (Python) - Sandboxed code execution
+8. **image-gen** (Python) - DALL-E/Stable Diffusion
+9. **file-ops** (Go) - File system operations
+10. **calculator** (Python) - Math evaluation
+
+### Community Extensions (Example Ideas)
+
+- **slack-integration** - Post to Slack channels
+- **github-integration** - Create issues, PRs
+- **email-sender** - Send emails via SMTP
+- **pdf-parser** - Extract text from PDFs
+- **scraper** - Web scraping tool
+- **translate** - Multi-language translation
+- **tts** - Text-to-speech
+- **stt** - Speech-to-text
+
+---
+
+## Next Steps
+
+1. Read `docs/ARCHITECTURE.md` for system overview
+2. Check `extensions/_template-python/` for starter code
+3. Browse `extensions/backend/` for examples
+4. Join developer Discord for help
+
+**Build something awesome! 🚀**