Validate depedencies needed for subprocess to start

internal/proxy/proxy.go

@@ -100,7 +100,6 @@ func NewRouter(cfg *config.Config, provider authz.Provider) http.Handler {
 
 func buildProxyHandler(cfg *config.Config, modifiers map[string]RequestModifier) http.HandlerFunc {
 	// Parse the base URLs up front
-
 	authBase, err := url.Parse(cfg.AuthServerBaseURL)
 	if err != nil {
 		log.Fatalf("Invalid auth server URL: %v", err)
@@ -191,19 +190,13 @@ func buildProxyHandler(cfg *config.Config, modifiers map[string]RequestModifier)
 				req.URL.RawQuery = r.URL.RawQuery
 				req.Host = targetURL.Host
 
-				// for key, values := range r.Header {
-				// 	log.Printf("Header: %s, Values: %v", key, values)
-				// }
-
 				cleanHeaders := http.Header{}
 				
-				// Preserve the original Origin header if present
+				// Set proper origin header to match the target
-				// if origin := r.Header.Get("Origin"); origin != "" {
+				if isSSE {
-				// 	cleanHeaders.Set("Origin", origin)
+					// For SSE, ensure origin matches the target
-				// } else {
+					req.Header.Set("Origin", targetURL.Scheme+"://"+targetURL.Host)
-				// 	log.Printf("[proxy] No Origin header found, setting to target URL: http://localhost:8080")
+				}
-				// 	cleanHeaders.Set("Origin", "http://localhost:8080")
-				// }
 				
 				for k, v := range r.Header {
 					// Skip hop-by-hop headers
@@ -232,6 +225,18 @@ func buildProxyHandler(cfg *config.Config, modifiers map[string]RequestModifier)
 		}
 
 		if isSSE {
+			// Add special response handling for SSE connections to rewrite endpoint URLs
+			rp.Transport = &sseTransport{
+				Transport:  http.DefaultTransport,
+				proxyHost:  r.Host,
+				targetHost: targetURL.Host,
+			}
+			
+			// Set SSE-specific headers
+			w.Header().Set("X-Accel-Buffering", "no")
+			w.Header().Set("Cache-Control", "no-cache")
+			w.Header().Set("Connection", "keep-alive")
+			
 			// Keep SSE connections open
 			HandleSSE(w, r, rp)
 		} else {

internal/subprocess/manager.go

@@ -7,6 +7,8 @@ import (
 	"sync"
 	"syscall"
 	"time"
+	"fmt"
+	"strings"
 
 	"github.com/wso2/open-mcp-auth-proxy/internal/config"
 )
@@ -27,6 +29,38 @@ func NewManager() *Manager {
 	}
 }
 
+// EnsureDependenciesAvailable checks and installs required package executors
+func EnsureDependenciesAvailable(command string) error {
+    // Always ensure npx is available regardless of the command
+    if _, err := exec.LookPath("npx"); err != nil {
+        // npx is not available, check if npm is installed
+        if _, err := exec.LookPath("npm"); err != nil {
+            return fmt.Errorf("npx not found and npm not available; please install Node.js from https://nodejs.org/")
+        }
+        
+        // Try to install npx using npm
+        log.Printf("npx not found, attempting to install...")
+        cmd := exec.Command("npm", "install", "-g", "npx")
+        cmd.Stdout = os.Stdout
+        cmd.Stderr = os.Stderr
+        
+        if err := cmd.Run(); err != nil {
+            return fmt.Errorf("failed to install npx: %w", err)
+        }
+        
+        log.Printf("npx installed successfully")
+    }
+    
+    // Check if uv is needed based on the command
+    if strings.Contains(command, "uv ") {
+        if _, err := exec.LookPath("uv"); err != nil {
+            return fmt.Errorf("command requires uv but it's not installed; please install it following instructions at https://github.com/astral-sh/uv")
+        }
+    }
+    
+    return nil
+}
+
 // SetShutdownDelay sets the maximum time to wait for graceful shutdown
 func (m *Manager) SetShutdownDelay(duration time.Duration) {
 	m.shutdownDelay = duration