Go：Add build pipeline for go server and fix web login bug

server/go/cmd/main.go

@@ -668,6 +668,15 @@ func main() {
 
 	log := logger.New(logCfg)
 
+	// Track env vars where we fell back to a built-in default. Printed once
+	// at the end of startup so the operator sees what's in effect — vars the
+	// operator explicitly set are NOT listed (they already know their value).
+	type defaultedEnv struct{ name, value string }
+	var defaultsUsed []defaultedEnv
+	rememberDefault := func(name, value string) {
+		defaultsUsed = append(defaultsUsed, defaultedEnv{name, value})
+	}
+
 	// Create auth config
 	authCfg := auth.DefaultConfig()
 	// PwdHash can be set from environment or config file
@@ -675,6 +684,7 @@ func main() {
 	if authCfg.PwdHash == "" {
 		// Default placeholder - should be configured in production
 		authCfg.PwdHash = "61f04dd637a74ee34493fc1025de2c131022536da751c29e3ff4e9024d8eec43"
+		rememberDefault("YAMA_PWDHASH", authCfg.PwdHash)
 	}
 	authCfg.SuperPass = os.Getenv("YAMA_PWD")
 
@@ -721,19 +731,23 @@ func main() {
 	// Web user authenticator. Bootstrap admin from env var YAMA_WEB_ADMIN_PASS;
 	// if unset, fall back to YAMA_PWD (same secret the TCP authorization uses)
 	// so a single password env var is enough to bring up the whole stack.
-	// If neither is set, no admin is registered and login will always fail —
-	// the user must define a password before browsers can log in.
+	// If neither is set we use a hard-coded "admin" default so the web UI is
+	// usable out of the box — the startup banner surfaces this so operators
+	// know to override it in any non-dev deployment.
+	const defaultWebAdminPass = "admin"
 	webAuth := wsauth.New()
 	adminPass := os.Getenv("YAMA_WEB_ADMIN_PASS")
 	if adminPass == "" {
 		adminPass = os.Getenv("YAMA_PWD")
 	}
-	if adminPass != "" {
-		webAuth.AddAdminFromPlainPassword("admin", adminPass)
-		log.Info("Web admin user configured")
-	} else {
-		log.Warn("Neither YAMA_WEB_ADMIN_PASS nor YAMA_PWD is set; web login will be unavailable")
+	usingDefaultWebPass := false
+	if adminPass == "" {
+		adminPass = defaultWebAdminPass
+		rememberDefault("YAMA_WEB_ADMIN_PASS", defaultWebAdminPass)
+		usingDefaultWebPass = true
 	}
+	webAuth.AddAdminFromPlainPassword("admin", adminPass)
+	log.Info("Web admin user configured")
 
 	// Persistent users live in users.json next to the binary's working dir
 	// — same default the C++ WebService uses (m_ConfigDir + "users.json").
@@ -741,6 +755,7 @@ func main() {
 	usersFile := os.Getenv("YAMA_USERS_FILE")
 	if usersFile == "" {
 		usersFile = "users.json"
+		rememberDefault("YAMA_USERS_FILE", usersFile)
 	}
 	if err := webAuth.SetUsersFile(usersFile); err != nil {
 		log.Warn("Failed to load %s: %v (continuing with admin only)", usersFile, err)
@@ -849,10 +864,21 @@ func main() {
 	fmt.Printf("Server started on port(s): %v\n", ports)
 	if *httpPort != 0 {
 		fmt.Printf("Web UI on http://localhost:%d/\n", *httpPort)
+		if usingDefaultWebPass {
+			fmt.Printf("    Default login: admin / %s   (set YAMA_WEB_ADMIN_PASS to override)\n",
+				defaultWebAdminPass)
+		}
 	}
 	if licenseHTTP != nil {
 		fmt.Printf("License Server on http://%s/license/{sign,heartbeat}\n", licAddr)
 	}
+	if len(defaultsUsed) > 0 {
+		fmt.Println()
+		fmt.Println("[!] Using built-in defaults (set the env var to override):")
+		for _, d := range defaultsUsed {
+			fmt.Printf("    %s = %s\n", d.name, d.value)
+		}
+	}
 	fmt.Println("Logs are written to: logs/server.log")
 	fmt.Println("Press Ctrl+C to stop...")