fix: prevent 301 redirect to relative path (./) when accessing root without trailing slash (addresses #334)

- Replaced http.FileServer with custom file serving to avoid automatic directory redirects
- Manually serve index.html for root path requests
- Custom routing bypasses ServeMux for frontend files to prevent redirect behavior
- This fixes reverse proxy and Cloudflare tunnel compatibility issues

internal/api/frontend_embed.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"embed"
+	"io"
 	"io/fs"
 	"net/http"
 	"strings"
@@ -32,15 +33,39 @@ func serveFrontendHandler() http.HandlerFunc {
 		log.Fatal().Err(err).Msg("Failed to get embedded frontend")
 	}
 	
-	fileServer := http.FileServer(fsys)
-	
 	return func(w http.ResponseWriter, r *http.Request) {
 		// Clean the path
 		p := r.URL.Path
 		
-		// Default to index.html for root
-		if p == "/" {
-			p = "/index.html"
+		// Handle root path specially to avoid FileServer's directory redirect
+		// Issue #334: Serve index.html directly without using FileServer for root
+		if p == "/" || p == "" {
+			// Directly serve index.html content
+			file, err := fsys.Open("index.html")
+			if err != nil {
+				http.NotFound(w, r)
+				return
+			}
+			defer file.Close()
+			
+			// Check that it's not a directory
+			_, err = file.Stat()
+			if err != nil {
+				http.NotFound(w, r)
+				return
+			}
+			
+			// Read the file content
+			content, err := io.ReadAll(file)
+			if err != nil {
+				http.NotFound(w, r)
+				return
+			}
+			
+			// Serve the content
+			w.Header().Set("Content-Type", "text/html; charset=utf-8")
+			w.Write(content)
+			return
 		}
 		
 		// Remove leading slash for filesystem lookup
@@ -49,10 +74,33 @@ func serveFrontendHandler() http.HandlerFunc {
 		// Check if file exists in embedded FS
 		file, err := fsys.Open(lookupPath)
 		if err == nil {
-			file.Close()
-			// File exists, serve it
-			fileServer.ServeHTTP(w, r)
-			return
+			defer file.Close()
+			
+			// Get file info
+			stat, err := file.Stat()
+			if err == nil && !stat.IsDir() {
+				// Read and serve the file
+				content, err := io.ReadAll(file)
+				if err == nil {
+					// Detect content type
+					contentType := "application/octet-stream"
+					if strings.HasSuffix(lookupPath, ".html") {
+						contentType = "text/html; charset=utf-8"
+					} else if strings.HasSuffix(lookupPath, ".css") {
+						contentType = "text/css; charset=utf-8"
+					} else if strings.HasSuffix(lookupPath, ".js") {
+						contentType = "application/javascript; charset=utf-8"
+					} else if strings.HasSuffix(lookupPath, ".json") {
+						contentType = "application/json"
+					} else if strings.HasSuffix(lookupPath, ".svg") {
+						contentType = "image/svg+xml"
+					}
+					
+					w.Header().Set("Content-Type", contentType)
+					w.Write(content)
+					return
+				}
+			}
 		}
 		
 		// For SPA routing, serve index.html for non-API routes
@@ -60,9 +108,16 @@ func serveFrontendHandler() http.HandlerFunc {
 		   !strings.HasPrefix(p, "/ws") && 
 		   !strings.HasPrefix(p, "/socket.io/") {
 			// Serve index.html for client-side routing
-			r.URL.Path = "/index.html"
-			fileServer.ServeHTTP(w, r)
-			return
+			indexFile, err := fsys.Open("index.html")
+			if err == nil {
+				defer indexFile.Close()
+				content, err := io.ReadAll(indexFile)
+				if err == nil {
+					w.Header().Set("Content-Type", "text/html; charset=utf-8")
+					w.Write(content)
+					return
+				}
+			}
 		}
 		
 		// Not found

internal/api/middleware.go

@@ -30,6 +30,12 @@ func (e *APIError) Error() string {
 // ErrorHandler is a middleware that handles panics and errors
 func ErrorHandler(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Fix for issue #334: Normalize empty path to "/" before ServeMux processes it
+		// This prevents the automatic redirect from "" to "./"
+		if r.URL.Path == "" {
+			r.URL.Path = "/"
+		}
+		
 		// Skip error handling for WebSocket endpoints
 		if r.Header.Get("Upgrade") == "websocket" {
 			next.ServeHTTP(w, r)

internal/api/router.go

@@ -636,9 +636,8 @@ func (r *Router) setupRoutes() {
 	// Simple stats page
 	r.mux.HandleFunc("/simple-stats", r.handleSimpleStats)
 	
-	// Serve embedded frontend
-	log.Info().Msg("Serving embedded frontend")
-	r.mux.Handle("/", serveFrontendHandler())
+	// Note: Frontend handler is handled manually in ServeHTTP to prevent redirect issues
+	// See issue #334 - ServeMux redirects empty path to "./" which breaks reverse proxies
 
 }
 
@@ -658,6 +657,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		w.WriteHeader(http.StatusOK)
 		return
 	}
+	
 
 	// Check if we need authentication
 	needsAuth := true
@@ -798,7 +798,24 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 
 		// Log request
 		start := time.Now()
-		r.mux.ServeHTTP(w, req)
+		
+		// Fix for issue #334: Custom routing to prevent ServeMux's "./" redirect
+		// When accessing without trailing slash, ServeMux redirects to "./" which is wrong
+		// We handle routing manually to avoid this issue
+		
+		// Check if this is an API or WebSocket route
+		if strings.HasPrefix(req.URL.Path, "/api/") || 
+		   strings.HasPrefix(req.URL.Path, "/ws") || 
+		   strings.HasPrefix(req.URL.Path, "/socket.io/") ||
+		   req.URL.Path == "/simple-stats" {
+			// Use the mux for API and special routes
+			r.mux.ServeHTTP(w, req)
+		} else {
+			// Serve frontend for all other paths (including root)
+			handler := serveFrontendHandler()
+			handler(w, req)
+		}
+		
 		log.Debug().
 			Str("method", req.Method).
 			Str("path", req.URL.Path).