Add auto-open browser on server start with -no-open flag

go.mod

@@ -1,3 +1,8 @@
 module github.com/kitproj/diff-server
 
 go 1.24.4
+
+require (
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
+	golang.org/x/sys v0.1.0 // indirect
+)

go.sum

@@ -0,0 +1,4 @@
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c h1:+mdjkGKdHQG3305AYmdv1U2eRNDiU2ErMBj1gwrq8eQ=
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
+golang.org/x/sys v0.1.0 h1:kunALQeHf1/185U1i0GOB/fy1IPRDDpuoOOqRReG57U=
+golang.org/x/sys v0.1.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

main.go

@@ -3,13 +3,17 @@ package main
 import (
 	"flag"
 	"fmt"
+	"net"
 	"net/http"
 	"os"
+
+	"github.com/pkg/browser"
 )
 
 func main() {
 	port := flag.String("p", "3844", "Port to listen on")
 	workspaceDir := flag.String("C", ".", "Directory to scan for git repositories")
+	noBrowser := flag.Bool("B", false, "Disable auto-opening browser")
 	flag.Parse()
 
 	if err := os.Chdir(*workspaceDir); err != nil {
@@ -19,8 +23,22 @@ func main() {
 
 	http.HandleFunc("/", diffsHandler)
 
-	fmt.Printf("Starting server on http://localhost:%s\n", *port)
-	if err := http.ListenAndServe(":"+*port, nil); err != nil {
+	listener, err := net.Listen("tcp", ":"+*port)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Server failed: %v\n", err)
+		os.Exit(1)
+	}
+
+	url := fmt.Sprintf("http://localhost:%s", *port)
+	fmt.Printf("Starting server on %s\n", url)
+
+	if !*noBrowser {
+		if err := browser.OpenURL(url); err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to open browser: %v\n", err)
+		}
+	}
+
+	if err := http.Serve(listener, nil); err != nil {
 		fmt.Fprintf(os.Stderr, "Server failed: %v\n", err)
 		os.Exit(1)
 	}