fix: 修复写队列 busy 恢复、关闭安全、备份与配置构建问题

internal/config/config.go

@@ -12,6 +12,9 @@ import (
 // MaxBodyBytesCap 是 max_body_bytes 的硬上限（DEVELOPMENT 11.1）。
 const MaxBodyBytesCap = 262144
 
+// MaxFrameBytesCap 是 max_frame_bytes 的硬上限，与 broker MaximumPacketSize 一致。
+const MaxFrameBytesCap = 786432
+
 // Config 对应 DEVELOPMENT 第 11.1 节的配置文件。
 type Config struct {
 	Listen               string        `yaml:"listen"`
@@ -124,39 +127,8 @@ func applyEmptyDefaults(cfg *Config) {
 	if cfg.Log.Level == "" {
 		cfg.Log.Level = def.Log.Level
 	}
-	if cfg.Limits.MaxBodyBytes == 0 {
-		cfg.Limits.MaxBodyBytes = def.Limits.MaxBodyBytes
-	}
-	if cfg.Limits.MaxMetaBytes == 0 {
-		cfg.Limits.MaxMetaBytes = def.Limits.MaxMetaBytes
-	}
-	if cfg.Limits.MaxFrameBytes == 0 {
-		cfg.Limits.MaxFrameBytes = def.Limits.MaxFrameBytes
-	}
-	if cfg.Limits.MaxTTLSeconds == 0 {
-		cfg.Limits.MaxTTLSeconds = def.Limits.MaxTTLSeconds
-	}
-	if cfg.Limits.MaxScheduleSeconds == 0 {
-		cfg.Limits.MaxScheduleSeconds = def.Limits.MaxScheduleSeconds
-	}
-	if cfg.Limits.MaxGroupMembers == 0 {
-		cfg.Limits.MaxGroupMembers = def.Limits.MaxGroupMembers
-	}
-	if cfg.Limits.GraceSeconds == 0 {
-		cfg.Limits.GraceSeconds = def.Limits.GraceSeconds
-	}
-	if cfg.Limits.AckTimeoutSeconds == 0 {
-		cfg.Limits.AckTimeoutSeconds = def.Limits.AckTimeoutSeconds
-	}
-	if cfg.Limits.DeliveryWindow == 0 {
-		cfg.Limits.DeliveryWindow = def.Limits.DeliveryWindow
-	}
-	if cfg.Limits.ReceiptWindow == 0 {
-		cfg.Limits.ReceiptWindow = def.Limits.ReceiptWindow
-	}
-	if cfg.Limits.RequestsPerSecond == 0 {
-		cfg.Limits.RequestsPerSecond = def.Limits.RequestsPerSecond
-	}
+	// 数值字段不在这里把 0 改回默认：Load 已先填 Default 再解析 YAML，
+	// 未写的字段保留默认值；显式写 0 对 grace 等字段有意义，其余由 Validate 拒绝。
 }
 
 // Validate 校验 DEVELOPMENT 11.1 全部字段；拒绝 max_body_bytes > 262144。
@@ -189,6 +161,9 @@ func (c Config) Validate() error {
 	if c.Limits.MaxFrameBytes <= 0 {
 		errs = append(errs, "limits.max_frame_bytes must be > 0")
 	}
+	if c.Limits.MaxFrameBytes > MaxFrameBytesCap {
+		errs = append(errs, fmt.Sprintf("limits.max_frame_bytes must be <= %d", MaxFrameBytesCap))
+	}
 	if c.Limits.MaxFrameBytes < c.Limits.MaxBodyBytes {
 		errs = append(errs, "limits.max_frame_bytes must be >= limits.max_body_bytes")
 	}