feat: detect ACTIONS_RUNNER_DEBUG and enable full logging

pkg/logger/logger.go

@@ -23,7 +23,8 @@ type Logger struct {
 
 var (
 	// DEBUG environment variable value, read once at initialization.
-	debugEnv = os.Getenv("DEBUG")
+	// If DEBUG is not set but ACTIONS_RUNNER_DEBUG=true, all loggers are enabled.
+	debugEnv = initDebugEnv()
 
 	// DEBUG_COLORS environment variable to control color output.
 	debugColors = os.Getenv("DEBUG_COLORS") != "0"
@@ -51,6 +52,19 @@ var (
 	colorReset = "\033[0m"
 )
 
+// initDebugEnv resolves the effective debug pattern.
+// If DEBUG is set, it takes precedence. Otherwise, if ACTIONS_RUNNER_DEBUG=true,
+// all loggers are enabled (equivalent to DEBUG=*).
+func initDebugEnv() string {
+	if d := os.Getenv("DEBUG"); d != "" {
+		return d
+	}
+	if os.Getenv("ACTIONS_RUNNER_DEBUG") == "true" {
+		return "*"
+	}
+	return ""
+}
+
 // New creates a new Logger for the given namespace.
 // The enabled state is computed at construction time based on the DEBUG environment variable.
 // DEBUG syntax follows https://www.npmjs.com/package/debug patterns:

pkg/logger/logger_test.go

@@ -332,6 +332,52 @@ func TestColorDisabling(t *testing.T) {
 	}
 }
 
+func TestInitDebugEnv(t *testing.T) {
+	tests := []struct {
+		name               string
+		debugEnvVal        string
+		actionsRunnerDebug string
+		want               string
+	}{
+		{
+			name:               "DEBUG takes precedence over ACTIONS_RUNNER_DEBUG",
+			debugEnvVal:        "cli:*",
+			actionsRunnerDebug: "true",
+			want:               "cli:*",
+		},
+		{
+			name:               "ACTIONS_RUNNER_DEBUG=true enables all loggers",
+			debugEnvVal:        "",
+			actionsRunnerDebug: "true",
+			want:               "*",
+		},
+		{
+			name:               "ACTIONS_RUNNER_DEBUG=false does not enable loggers",
+			debugEnvVal:        "",
+			actionsRunnerDebug: "false",
+			want:               "",
+		},
+		{
+			name:               "neither set returns empty",
+			debugEnvVal:        "",
+			actionsRunnerDebug: "",
+			want:               "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("DEBUG", tt.debugEnvVal)
+			t.Setenv("ACTIONS_RUNNER_DEBUG", tt.actionsRunnerDebug)
+
+			got := initDebugEnv()
+			if got != tt.want {
+				t.Errorf("initDebugEnv() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
 func TestMatchPattern(t *testing.T) {
 	tests := []struct {
 		name      string