diff --git a/cmd/serve.go b/cmd/serve.go
index d0e8064..71c6171 100644
--- a/cmd/serve.go
+++ b/cmd/serve.go
@@ -141,6 +141,9 @@ func runServe(cmd *cobra.Command, args []string) {
 	// Site enhancement endpoint
 	apiRouter.HandleFunc("/enhance", contentHandler.EnhanceSite).Methods("POST")
 
+	// Static library serving (for demo sites)
+	router.HandleFunc("/insertr.js", contentHandler.ServeInsertrJS).Methods("GET")
+
 	// Handle CORS preflight requests explicitly
 	contentRouter.HandleFunc("/{id}", api.CORSPreflightHandler).Methods("OPTIONS")
 	contentRouter.HandleFunc("", api.CORSPreflightHandler).Methods("OPTIONS")
diff --git a/insertr.yaml b/insertr.yaml
index efc5e37..ce457c4 100644
--- a/insertr.yaml
+++ b/insertr.yaml
@@ -33,6 +33,7 @@ server:
 cli:
   site_id: "demo"       # Default site ID for CLI operations
   output: "./dist"      # Default output directory for enhanced files
+  inject_demo_gate: true  # Inject demo gate in development mode if no gates exist
   
 # API client configuration (for CLI remote mode)
 api:
diff --git a/internal/api/handlers.go b/internal/api/handlers.go
index 851e4ba..01002a8 100644
--- a/internal/api/handlers.go
+++ b/internal/api/handlers.go
@@ -5,8 +5,10 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -717,3 +719,30 @@ func (h *ContentHandler) generateContentID(ctx *ElementContext) string {
 	idGenerator := parser.NewIDGenerator()
 	return idGenerator.Generate(virtualNode, "api-generated")
 }
+
+// ServeInsertrJS handles GET /insertr.js - serves the insertr JavaScript library
+func (h *ContentHandler) ServeInsertrJS(w http.ResponseWriter, r *http.Request) {
+	// Path to the built insertr.js file
+	jsPath := "lib/dist/insertr.js"
+
+	// Check if file exists
+	if _, err := os.Stat(jsPath); os.IsNotExist(err) {
+		http.Error(w, "insertr.js not found - run 'just build-lib' to build the library", http.StatusNotFound)
+		return
+	}
+
+	// Open and serve the file
+	file, err := os.Open(jsPath)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("Failed to open insertr.js: %v", err), http.StatusInternalServerError)
+		return
+	}
+	defer file.Close()
+
+	// Set appropriate headers
+	w.Header().Set("Content-Type", "application/javascript")
+	w.Header().Set("Cache-Control", "no-cache") // For development
+
+	// Copy file contents to response
+	io.Copy(w, file)
+}
diff --git a/internal/api/middleware.go b/internal/api/middleware.go
index 0a94037..8183096 100644
--- a/internal/api/middleware.go
+++ b/internal/api/middleware.go
@@ -3,6 +3,7 @@ package api
 import (
 	"log"
 	"net/http"
+	"strings"
 	"time"
 )
 
@@ -11,24 +12,8 @@ func CORSMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		origin := r.Header.Get("Origin")
 
-		// Allow localhost and 127.0.0.1 on common development ports
-		allowedOrigins := []string{
-			"http://localhost:3000",
-			"http://127.0.0.1:3000",
-			"http://localhost:8080",
-			"http://127.0.0.1:8080",
-		}
-
-		// Check if origin is allowed
-		originAllowed := false
-		for _, allowed := range allowedOrigins {
-			if origin == allowed {
-				originAllowed = true
-				break
-			}
-		}
-
-		if originAllowed {
+		// In development mode, allow all localhost origins including demo sites
+		if isLocalhostOrigin(origin) {
 			w.Header().Set("Access-Control-Allow-Origin", origin)
 		} else {
 			// Fallback to wildcard for development (can be restricted in production)
@@ -97,8 +82,8 @@ func CORSPreflightHandler(w http.ResponseWriter, r *http.Request) {
 	// Allow localhost and 127.0.0.1 on common development ports
 	allowedOrigins := []string{
 		"http://localhost:3000",
-		"http://127.0.0.1:3000",
 		"http://localhost:8080",
+		"http://127.0.0.1:3000",
 		"http://127.0.0.1:8080",
 	}
 
@@ -125,3 +110,20 @@ func CORSPreflightHandler(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusOK)
 }
+
+// isLocalhostOrigin checks if an origin is a localhost/127.0.0.1 development origin
+func isLocalhostOrigin(origin string) bool {
+	if origin == "" {
+		return false
+	}
+
+	// Allow localhost and 127.0.0.1 on any port for development
+	return strings.HasPrefix(origin, "http://localhost:") ||
+		strings.HasPrefix(origin, "https://localhost:") ||
+		strings.HasPrefix(origin, "http://127.0.0.1:") ||
+		strings.HasPrefix(origin, "https://127.0.0.1:") ||
+		origin == "http://localhost" ||
+		origin == "https://localhost" ||
+		origin == "http://127.0.0.1" ||
+		origin == "https://127.0.0.1"
+}
diff --git a/internal/content/injector.go b/internal/content/injector.go
index 29d8eaa..1f3cf86 100644
--- a/internal/content/injector.go
+++ b/internal/content/injector.go
@@ -209,17 +209,17 @@ func (i *Injector) AddContentAttributes(node *html.Node, contentID string, conte
 	i.addClass(node, "insertr")
 }
 
-// InjectEditorAssets adds editor JavaScript to HTML document
+// InjectEditorAssets adds editor JavaScript to HTML document and injects demo gate if needed
 func (i *Injector) InjectEditorAssets(doc *html.Node, isDevelopment bool, libraryScript string) {
-	// TODO: Implement script injection strategy when we have CDN hosting
-	// For now, script injection is disabled since HTML files should include their own script tags
-	// Future options:
-	// 1. Inject CDN script tag: <script src="https://cdn.jsdelivr.net/npm/@insertr/lib@1.0.0/dist/insertr.js"></script>
-	// 2. Inject local script tag for development: <script src="/insertr/insertr.js"></script>
-	// 3. Continue with inline injection for certain use cases
+	// Inject demo gate if no gates exist and add script for functionality
+	if isDevelopment {
+		i.InjectDemoGateIfNeeded(doc)
+		i.InjectEditorScript(doc)
+	}
 
-	// Currently disabled to avoid duplicate scripts
-	return
+	// TODO: Implement CDN script injection for production
+	// Production options:
+	// 1. Inject CDN script tag: <script src="https://cdn.jsdelivr.net/npm/@insertr/lib@1.0.0/dist/insertr.js"></script>
 }
 
 // findHeadElement finds the <head> element in the document
@@ -310,3 +310,196 @@ type ElementWithID struct {
 	Element   *Element
 	ContentID string
 }
+
+// InjectDemoGateIfNeeded injects a demo gate element if no .insertr-gate elements exist
+func (i *Injector) InjectDemoGateIfNeeded(doc *html.Node) {
+	// Check if any .insertr-gate elements already exist
+	if i.hasInsertrGate(doc) {
+		return
+	}
+
+	// Find the body element
+	bodyNode := i.findBodyElement(doc)
+	if bodyNode == nil {
+		log.Printf("Warning: Could not find body element to inject demo gate")
+		return
+	}
+
+	// Create demo gate HTML structure
+	gateHTML := `<div class="insertr-demo-gate" style="position: fixed; top: 20px; right: 20px; z-index: 9999; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;">
+    <button class="insertr-gate insertr-demo-gate-btn" style="background: #4f46e5; color: white; border: none; padding: 10px 16px; border-radius: 8px; font-size: 14px; font-weight: 500; cursor: pointer; box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3); transition: all 0.2s ease; display: flex; align-items: center; gap: 8px; user-select: none;" onmouseover="this.style.background='#4338ca'; this.style.transform='translateY(-2px)'; this.style.boxShadow='0 6px 16px rgba(79, 70, 229, 0.4)'" onmouseout="this.style.background='#4f46e5'; this.style.transform='translateY(0)'; this.style.boxShadow='0 4px 12px rgba(79, 70, 229, 0.3)'">
+        <span style="font-size: 16px;">✏️</span>
+        <span>Edit Site</span>
+    </button>
+</div>`
+
+	// Parse the gate HTML and inject it into the body
+	gateDoc, err := html.Parse(strings.NewReader(gateHTML))
+	if err != nil {
+		log.Printf("Error parsing demo gate HTML: %v", err)
+		return
+	}
+
+	// Extract and inject the gate element
+	if gateDiv := i.extractElementByClass(gateDoc, "insertr-demo-gate"); gateDiv != nil {
+		if gateDiv.Parent != nil {
+			gateDiv.Parent.RemoveChild(gateDiv)
+		}
+		bodyNode.AppendChild(gateDiv)
+		log.Printf("✅ Demo gate injected: Edit button added to top-right corner")
+	}
+}
+
+// InjectEditorScript injects the insertr.js library and initialization script
+func (i *Injector) InjectEditorScript(doc *html.Node) {
+	// Find the head element for the script tag
+	headNode := i.findHeadElement(doc)
+	if headNode == nil {
+		log.Printf("Warning: Could not find head element to inject editor script")
+		return
+	}
+
+	// Create script element that loads insertr.js from our server
+	scriptHTML := fmt.Sprintf(`<script src="http://localhost:8080/insertr.js"></script>
+<script type="text/javascript">
+// Initialize insertr for demo sites
+document.addEventListener('DOMContentLoaded', function() {
+    if (typeof window.Insertr !== 'undefined') {
+        console.log('✅ Insertr library loaded successfully');
+        
+        // The library has auto-initialization, but we can force initialization
+        // with our demo configuration
+        window.Insertr.init({
+            siteId: '%s',
+            apiEndpoint: 'http://localhost:8080/api/content',
+            mockAuth: true, // Use mock authentication for demos
+            debug: true
+        });
+        
+        console.log('✅ Insertr initialized for demo site with config:', {
+            siteId: '%s',
+            apiEndpoint: 'http://localhost:8080/api/content',
+            mockAuth: true
+        });
+    } else {
+        console.error('❌ Insertr library failed to load');
+        
+        // Fallback for demo gates if library fails
+        const gates = document.querySelectorAll('.insertr-gate');
+        gates.forEach(gate => {
+            gate.addEventListener('click', function(e) {
+                e.preventDefault();
+                alert('🚧 Insertr library not loaded\\n\\nPlease run "just build-lib" to build the library first.');
+            });
+        });
+    }
+});
+</script>`, i.siteID, i.siteID)
+
+	// Parse and inject the script
+	scriptDoc, err := html.Parse(strings.NewReader(scriptHTML))
+	if err != nil {
+		log.Printf("Error parsing editor script HTML: %v", err)
+		return
+	}
+
+	// Extract and inject all script elements
+	if err := i.injectAllScriptElements(scriptDoc, headNode); err != nil {
+		log.Printf("Error injecting script elements: %v", err)
+		return
+	}
+
+	log.Printf("✅ Insertr.js library and initialization script injected")
+}
+
+// injectAllScriptElements finds and injects all script elements from parsed HTML
+func (i *Injector) injectAllScriptElements(doc *html.Node, targetNode *html.Node) error {
+	scripts := i.findAllScriptElements(doc)
+
+	for _, script := range scripts {
+		// Remove from original parent
+		if script.Parent != nil {
+			script.Parent.RemoveChild(script)
+		}
+		// Add to target node
+		targetNode.AppendChild(script)
+	}
+
+	return nil
+}
+
+// findAllScriptElements recursively finds all script elements
+func (i *Injector) findAllScriptElements(node *html.Node) []*html.Node {
+	var scripts []*html.Node
+
+	if node.Type == html.ElementNode && node.Data == "script" {
+		scripts = append(scripts, node)
+	}
+
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		childScripts := i.findAllScriptElements(child)
+		scripts = append(scripts, childScripts...)
+	}
+
+	return scripts
+}
+
+// hasInsertrGate checks if document has .insertr-gate elements
+func (i *Injector) hasInsertrGate(node *html.Node) bool {
+	if node.Type == html.ElementNode {
+		for _, attr := range node.Attr {
+			if attr.Key == "class" && strings.Contains(attr.Val, "insertr-gate") {
+				return true
+			}
+		}
+	}
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		if i.hasInsertrGate(child) {
+			return true
+		}
+	}
+	return false
+}
+
+// findBodyElement finds the <body> element
+func (i *Injector) findBodyElement(node *html.Node) *html.Node {
+	if node.Type == html.ElementNode && node.Data == "body" {
+		return node
+	}
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		if result := i.findBodyElement(child); result != nil {
+			return result
+		}
+	}
+	return nil
+}
+
+// extractElementByClass finds element with specific class
+func (i *Injector) extractElementByClass(node *html.Node, className string) *html.Node {
+	if node.Type == html.ElementNode {
+		for _, attr := range node.Attr {
+			if attr.Key == "class" && strings.Contains(attr.Val, className) {
+				return node
+			}
+		}
+	}
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		if result := i.extractElementByClass(child, className); result != nil {
+			return result
+		}
+	}
+	return nil
+}
+
+// extractElementByTag finds element with specific tag
+func (i *Injector) extractElementByTag(node *html.Node, tagName string) *html.Node {
+	if node.Type == html.ElementNode && node.Data == tagName {
+		return node
+	}
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		if result := i.extractElementByTag(child, tagName); result != nil {
+			return result
+		}
+	}
+	return nil
+}
diff --git a/justfile b/justfile
index 83c2a7a..a49f799 100644
--- a/justfile
+++ b/justfile
@@ -104,22 +104,22 @@ demo site="":
         if [ ! -d "./test-sites/simple/dan-eden-portfolio-demo" ]; then
             echo "🔧 Dan Eden demo not ready - auto-enhancing now..."
             just build
-            ./insertr auto-enhance test-sites/simple/dan-eden-portfolio --output test-sites/simple/dan-eden-portfolio-temp
-            ./insertr enhance test-sites/simple/dan-eden-portfolio-temp --output test-sites/simple/dan-eden-portfolio-demo --site-id dan-eden
+            ./insertr auto-enhance test-sites/simple/dan-eden-portfolio --output test-sites/simple/dan-eden-portfolio-temp --config test-sites/simple/dan-eden-portfolio/insertr.yaml
+            ./insertr enhance test-sites/simple/dan-eden-portfolio-temp --output test-sites/simple/dan-eden-portfolio-demo --config test-sites/simple/dan-eden-portfolio/insertr.yaml
             rm -rf test-sites/simple/dan-eden-portfolio-temp
         fi
         echo "🚀 Starting Dan Eden portfolio demo..."
-        just demo-site "dan-eden" "./test-sites/simple/dan-eden-portfolio-demo" "3001"
+        just demo-site "dan-eden" "./test-sites/simple/dan-eden-portfolio-demo" "3000"
     elif [ "{{site}}" = "simple" ]; then
         if [ ! -d "./test-sites/simple/test-simple-demo" ]; then
             echo "🔧 Simple demo not ready - auto-enhancing now..."
             just build
-            ./insertr auto-enhance test-sites/simple/test-simple --output test-sites/simple/test-simple-temp
-            ./insertr enhance test-sites/simple/test-simple-temp --output test-sites/simple/test-simple-demo --site-id simple
+            ./insertr auto-enhance test-sites/simple/test-simple --output test-sites/simple/test-simple-temp --config test-sites/simple/test-simple/insertr.yaml
+            ./insertr enhance test-sites/simple/test-simple-temp --output test-sites/simple/test-simple-demo --config test-sites/simple/test-simple/insertr.yaml
             rm -rf test-sites/simple/test-simple-temp
         fi
         echo "🚀 Starting simple test site demo..."
-        just demo-site "simple" "./test-sites/simple/test-simple-demo" "3002"
+        just demo-site "simple" "./test-sites/simple/test-simple-demo" "3000"
     else
         echo "❌ Unknown demo site: {{site}}"
         echo ""
diff --git a/test-sites/simple/dan-eden-portfolio/insertr.yaml b/test-sites/simple/dan-eden-portfolio/insertr.yaml
new file mode 100644
index 0000000..f56946f
--- /dev/null
+++ b/test-sites/simple/dan-eden-portfolio/insertr.yaml
@@ -0,0 +1,27 @@
+# Insertr Configuration for Dan Eden Portfolio Demo Site
+# Specific configuration for the Dan Eden portfolio demo
+
+# Global settings
+dev_mode: true           # Development mode for demos
+
+# Database configuration  
+database:
+  path: "./insertr.db"   # Shared database with main config
+
+# Demo-specific configuration
+demo:
+  site_id: "dan-eden"    # Unique site ID for Dan Eden demo
+  inject_demo_gate: true # Auto-inject demo gate if no gates exist
+  mock_auth: true        # Use mock authentication for demos
+  api_endpoint: "http://localhost:8080/api/content"
+  demo_port: 3000        # Port for live-server
+
+# CLI enhancement configuration
+cli:
+  site_id: "dan-eden"    # Site ID for this demo
+  output: "./dan-eden-demo" # Output directory for enhanced files
+  inject_demo_gate: true # Inject demo gate in development mode
+
+# Authentication configuration (for demo)
+auth:
+  provider: "mock"       # Mock auth for demos
\ No newline at end of file
diff --git a/test-sites/simple/test-simple/insertr.yaml b/test-sites/simple/test-simple/insertr.yaml
new file mode 100644
index 0000000..85c15b9
--- /dev/null
+++ b/test-sites/simple/test-simple/insertr.yaml
@@ -0,0 +1,27 @@
+# Insertr Configuration for Simple Demo Site
+# Specific configuration for the simple test site demo
+
+# Global settings
+dev_mode: true           # Development mode for demos
+
+# Database configuration  
+database:
+  path: "./insertr.db"   # Shared database with main config
+
+# Demo-specific configuration
+demo:
+  site_id: "simple"      # Unique site ID for simple demo
+  inject_demo_gate: true # Auto-inject demo gate if no gates exist
+  mock_auth: true        # Use mock authentication for demos
+  api_endpoint: "http://localhost:8080/api/content"
+  demo_port: 3000        # Port for live-server
+
+# CLI enhancement configuration
+cli:
+  site_id: "simple"      # Site ID for this demo
+  output: "./simple-demo" # Output directory for enhanced files
+  inject_demo_gate: true # Inject demo gate in development mode
+
+# Authentication configuration (for demo)
+auth:
+  provider: "mock"       # Mock auth for demos
\ No newline at end of file