fix(broker-router): honor --log-level=4 (warn) instead of defaulting to debug

The level switch in setupLogger only handled 0, 8 and -4, so warn (4) and
any other value fell through to the default case and were mapped to debug,
the most verbose level. The flag value is already a raw slog.Level, so map
it directly. The controller binary had the same switch; fixed there too,
and its --log-level help text now lists 4=warn.

Adds a unit test covering the info/warn/error/debug/arbitrary mappings.

Fixes #1143

Signed-off-by: PRAteek-singHWY <prateek23022004@gmail.com>

Author: PRAteek-singHWY

cmd/main.go

@@ -55,21 +55,12 @@ func init() {
 func main() {
 	var loglevel int
 	var logFormat string
-	flag.IntVar(&loglevel, "log-level", int(slog.LevelInfo), "log level: 0=info, 8=error, -4=debug")
+	flag.IntVar(&loglevel, "log-level", int(slog.LevelInfo), "log level: 0=info, 4=warn, 8=error, -4=debug")
 	flag.StringVar(&logFormat, "log-format", "txt", "log format: txt or json")
 	flag.Parse()
 
-	loggerOpts := &slog.HandlerOptions{}
-	switch loglevel {
-	case 0:
-		loggerOpts.Level = slog.LevelInfo
-	case 8:
-		loggerOpts.Level = slog.LevelError
-	case -4:
-		loggerOpts.Level = slog.LevelDebug
-	default:
-		loggerOpts.Level = slog.LevelDebug
-	}
+	// flag value is a raw slog.Level (info=0, warn=4, error=8, debug=-4)
+	loggerOpts := &slog.HandlerOptions{Level: slog.Level(loglevel)}
 
 	var slogger *slog.Logger
 	if logFormat == "json" {

cmd/mcp-broker-router/main.go

@@ -172,16 +172,8 @@ func parseFlags() *app {
 
 func (a *app) setupLogger() (*slog.HandlerOptions, bool) {
 	opts := &slog.HandlerOptions{}
-	switch a.brokerCfg.logLevel {
-	case 0:
-		opts.Level = slog.LevelInfo
-	case 8:
-		opts.Level = slog.LevelError
-	case -4:
-		opts.Level = slog.LevelDebug
-	default:
-		opts.Level = slog.LevelDebug
-	}
+	// flag value is a raw slog.Level (info=0, warn=4, error=8, debug=-4)
+	opts.Level = slog.Level(a.brokerCfg.logLevel)
 
 	jsonFormat := a.brokerCfg.logFormat == "json"
 	a.logger = mcpotel.NewTracingLogger(os.Stdout, opts, jsonFormat, nil)

cmd/mcp-broker-router/main_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"log/slog"
+	"testing"
+)
+
+func TestSetupLoggerLevelMapping(t *testing.T) {
+	cases := []struct {
+		name  string
+		level int
+		want  slog.Level
+	}{
+		{"info", 0, slog.LevelInfo},
+		{"warn", 4, slog.LevelWarn},
+		{"error", 8, slog.LevelError},
+		{"debug", -4, slog.LevelDebug},
+		{"arbitrary", 2, slog.Level(2)},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			a := &app{}
+			a.brokerCfg.logLevel = tc.level
+			opts, _ := a.setupLogger()
+			if got := opts.Level.Level(); got != tc.want {
+				t.Errorf("log-level=%d: got %v, want %v", tc.level, got, tc.want)
+			}
+		})
+	}
+}