perf: 消息内存按字节预算，杜绝大报文流撑爆内存

- 新增 MessageRing：条数上限 + 每连接 32MB 字节预算双重驱逐
  （从最旧丢弃，均摊 O(1)）；预分配容量按设置钳制在 512
- 单条 payload 保留上限 256KB → 128KB；MqttRecord::retained_bytes
  计入文本与原始字节，供预算驱逐与资源监控展示
- 清空消息统一走 clear_messages；设置页标注字节预算兜底说明
- 新增单元测试：条数驱逐、字节预算、超预算单条保留、驱逐顺序

gpui-app/src/model.rs

@@ -6,6 +6,8 @@ use std::sync::Arc;
 
 use serde::{Deserialize, Serialize};
 
+use std::collections::VecDeque;
+
 // ─── 连接配置 ────────────────────────────────────────────────────────────────
 
 /// MQTT 协议版本。
@@ -451,9 +453,70 @@ pub struct MqttRecord {
     pub raw_bytes: Option<Arc<[u8]>>,
 }
 
+impl MqttRecord {
+    /// 该记录保留的主要字节数（文本 + 原始字节），用于内存预算驱逐。
+    /// 其余字段（主题/属性等）相对小一个数量级，不计入。
+    pub fn retained_bytes(&self) -> usize {
+        self.payload.len() + self.raw_bytes.as_ref().map_or(0, |b| b.len())
+    }
+}
+
+/// 单连接的消息环形缓冲：条数上限 + [`MAX_CONNECTION_MESSAGE_BYTES`]
+/// 字节上限双重驱逐（从最旧开始，均摊 O(1)）。
+pub struct MessageRing {
+    queue: VecDeque<MqttRecord>,
+    bytes: usize,
+}
+
+impl MessageRing {
+    pub fn new(max_count: usize) -> Self {
+        Self {
+            // 预分配按较小值钳制：设置上限十万条时不一次性分配过大
+            queue: VecDeque::with_capacity(max_count.clamp(16, 512)),
+            bytes: 0,
+        }
+    }
+
+    /// `max_count` 每次传入以便运行时调整设置后即时生效。
+    /// 设置层已校验 ≥100，这里只防 0 值导致缓冲被清空。
+    pub fn push(&mut self, record: MqttRecord, max_count: usize) {
+        let max_count = max_count.max(1);
+        self.bytes += record.retained_bytes();
+        while self.queue.len() >= max_count
+            || (self.bytes > MAX_CONNECTION_MESSAGE_BYTES && self.queue.len() > 1)
+        {
+            let Some(old) = self.queue.pop_front() else { break };
+            self.bytes -= old.retained_bytes();
+        }
+        self.queue.push_back(record);
+    }
+
+    pub fn len(&self) -> usize {
+        self.queue.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.queue.is_empty()
+    }
+
+    /// 当前保留的字节数（payload + 原始字节）。
+    pub fn retained_bytes(&self) -> usize {
+        self.bytes
+    }
+
+    pub fn iter(&self) -> std::collections::vec_deque::Iter<'_, MqttRecord> {
+        self.queue.iter()
+    }
+}
+
 /// 消息历史中单条 payload 的保留上限。超限截断，避免个别大报文
 /// 长期占据历史缓冲（MQTTX 亦有类似限制）。
-pub const MAX_PAYLOAD_RETAIN: usize = 256 * 1024;
+pub const MAX_PAYLOAD_RETAIN: usize = 128 * 1024;
+
+/// 每连接消息历史的字节预算（payload + 原始字节）。条数上限
+/// （max_messages）在大报文流下形同虚设（2000 条 × 128KB ≈ 256MB），
+/// 超出预算后从最旧开始驱逐，保证单连接消息内存有上界。
+pub const MAX_CONNECTION_MESSAGE_BYTES: usize = 32 * 1024 * 1024;
 
 /// 把原始 payload 字节转成用于历史记录的共享文本，超限截断。
 /// 返回 (文本, 非文本时的原始字节, 是否截断)。截断时回退到 UTF-8 字符边界。
@@ -985,4 +1048,79 @@ mod tests {
         b.ssl.ca_file = "/tmp/ca.pem".into();
         assert!(a.session_params_changed(&b), "TLS 配置改动应触发重连提示");
     }
+
+    fn ring_record(seq: u64, payload_len: usize, raw_len: usize) -> MqttRecord {
+        MqttRecord {
+            seq,
+            connection_id: "c".into(),
+            direction: Direction::Received,
+            topic: "t".into(),
+            payload: Arc::from("a".repeat(payload_len)),
+            qos: 0,
+            retain: false,
+            timestamp: 0,
+            user_properties: Vec::new(),
+            content_type: None,
+            response_topic: None,
+            correlation_data: None,
+            message_expiry_interval: None,
+            subscription_identifier: None,
+            payload_truncated: false,
+            raw_bytes: if raw_len > 0 {
+                Some(Arc::from(vec![0u8; raw_len]))
+            } else {
+                None
+            },
+        }
+    }
+
+    // 消息环形缓冲：条数上限正常驱逐
+    #[test]
+    fn message_ring_enforces_count_limit() {
+        let mut ring = MessageRing::new(4);
+        for i in 0..10 {
+            ring.push(ring_record(i, 64, 0), 4);
+        }
+        assert_eq!(ring.len(), 4);
+        assert_eq!(
+            ring.iter().next().map(|r| r.seq),
+            Some(6),
+            "应从最旧开始驱逐"
+        );
+        assert_eq!(ring.retained_bytes(), 4 * 64);
+    }
+
+    // 消息环形缓冲：大报文流下字节预算优先于条数上限，内存有上界
+    #[test]
+    fn message_ring_enforces_byte_budget() {
+        let mut ring = MessageRing::new(2000);
+        // 每条 256KB（payload 128KB + raw 128KB）：2000 条本会到 512MB
+        let per = MAX_PAYLOAD_RETAIN;
+        for i in 0..2000 {
+            ring.push(ring_record(i, per, per), 2000);
+        }
+        assert!(
+            ring.retained_bytes() <= MAX_CONNECTION_MESSAGE_BYTES + 2 * per,
+            "字节数 {} 超出预算 {}",
+            ring.retained_bytes(),
+            MAX_CONNECTION_MESSAGE_BYTES
+        );
+        assert!(
+            ring.len() < 2000,
+            "大报文流不应保留满额条数（实际 {} 条）",
+            ring.len()
+        );
+        assert_eq!(ring.iter().next().map(|r| r.seq), Some((2000 - ring.len()) as u64));
+    }
+
+    // 单条超预算的记录也至少保留最新一条（列表不能被清空）
+    #[test]
+    fn message_ring_never_empties_on_oversized_record() {
+        let mut ring = MessageRing::new(10);
+        ring.push(ring_record(0, MAX_PAYLOAD_RETAIN, MAX_PAYLOAD_RETAIN), 10);
+        assert_eq!(ring.len(), 1);
+        ring.push(ring_record(1, 64, 0), 10);
+        assert_eq!(ring.len(), 2);
+        assert_eq!(ring.iter().next().map(|r| r.seq), Some(0));
+    }
 }

gpui-app/src/ui/app.rs

@@ -24,8 +24,8 @@ use gpui_kit::{
 use crate::aliyun::AliyunPreset;
 use crate::model::{
     AppSettings, ConnectionConfig, ConnectionStatus, Direction, GlobalVariable, LogEntry,
-    LogLevel, MqttRecord, PublishParams, PublishPreset, SubscribeOptions, Subscription,
+    LogLevel, MqttRecord, MessageRing, PublishParams, PublishPreset, SubscribeOptions,
-    ThemeModePref, retained_payload,
+    Subscription, ThemeModePref, retained_payload,
 };
 use crate::mqtt::{EngineEvent, MqttEngine};
 use crate::store::Storage;
@@ -84,8 +84,8 @@ pub struct MqttXApp {
     // ── 运行时状态 ──
     pub statuses: HashMap<String, ConnectionStatus>,
     pub errors: HashMap<String, String>,
-    /// 每连接消息环形缓冲：键为驻留后的连接 ID，容量受 max_messages 约束
+    /// 每连接消息环形缓冲：键为驻留后的连接 ID，条数 + 字节预算双重约束
-    pub messages: HashMap<Arc<str>, VecDeque<MqttRecord>>,
+    pub messages: HashMap<Arc<str>, MessageRing>,
     pub logs: VecDeque<LogEntry>,
     pub seq: u64,
 
@@ -473,16 +473,16 @@ impl MqttXApp {
     }
 
     fn push_message(&mut self, connection_id: Arc<str>, record: MqttRecord) {
-        let cap = self.settings.max_messages.max(100);
+        let cap = self.settings.max_messages;
-        let list = self
+        self.messages
-            .messages
             .entry(connection_id)
-            .or_insert_with(|| VecDeque::with_capacity(cap));
+            .or_insert_with(|| MessageRing::new(cap))
-        // 环形缓冲：满则丢最旧，均摊 O(1)（原来的 Vec::drain 是 O(n) 搬移）
+            .push(record, cap);
-        while list.len() >= cap {
+    }
-            list.pop_front();
+
-        }
+    /// 清空指定连接的消息（内存缓冲随 drop 释放）。
-        list.push_back(record);
+    pub fn clear_messages(&mut self, id: &str) {
+        self.messages.remove(id);
     }
 
     fn push_log(&mut self, entry: LogEntry) {
@@ -603,7 +603,7 @@ impl MqttXApp {
         self.engine.close(id, false);
         self.connections.retain(|c| c.id != id);
         self.subscriptions.retain(|s| s.connection_id != id);
-        self.messages.remove(id);
+        self.clear_messages(id);
         self.statuses.remove(id);
         self.errors.remove(id);
         self.views.remove(id);

gpui-app/src/ui/connection_view.rs

@@ -1765,7 +1765,7 @@ impl ConnectionView {
                                                 view.detail_format = DetailFormat::Auto;
                                                 if let Some(app) = view.app.upgrade() {
                                                     app.update(cx, |app, cx| {
-                                                        app.messages.remove(clear_id.as_str());
+                                                        app.clear_messages(&clear_id);
                                                         cx.notify();
                                                     });
                                                 }

gpui-app/src/ui/settings_dialog.rs

@@ -17,7 +17,7 @@ use gpui_kit::{
     Styled as _, Window,
 };
 
-use crate::model::{AppSettings, ThemeModePref};
+use crate::model::{AppSettings, ThemeModePref, MAX_CONNECTION_MESSAGE_BYTES};
 use crate::mqtt::MqttEngine;
 use crate::ui::app::MqttXApp;
 use crate::ui::widgets::{field, make_select, OptionDelegate};
@@ -388,6 +388,15 @@ impl Render for SettingsDialog {
                 "每条连接内存中保留的消息条数（100~100000）",
                 Input::new(&self.max_messages),
             ))
+            .child(
+                div()
+                    .text_xs()
+                    .text_color(cx.theme().muted_foreground)
+                    .child(format!(
+                        "另有每连接 {}MB 的字节预算兜底：大报文流会优先按字节从最旧开始驱逐",
+                        MAX_CONNECTION_MESSAGE_BYTES / (1024 * 1024)
+                    )),
+            )
             .child(
                 h_flex()
                     .justify_between()