feat: 实现消息发送的速率限制，确保同一用户之间的最小间隔

src/channels/wechat.rs

@@ -2,7 +2,7 @@ use std::collections::HashMap;
 use std::path::Path;
 use std::path::PathBuf;
 use std::sync::{
-    Arc,
+    Arc, Mutex,
     atomic::{AtomicBool, Ordering},
 };
 use std::time::{Duration, UNIX_EPOCH};
@@ -18,6 +18,44 @@ use crate::bus::message::OutboundEventKind;
 use crate::channels::base::{Channel, ChannelError};
 use crate::config::{LLMProviderConfig, WechatChannelConfig};
 
+/// Rate limiter: ensures minimum interval between messages to the same chat.
+static LAST_SEND: std::sync::LazyLock<Mutex<HashMap<String, tokio::time::Instant>>> =
+    std::sync::LazyLock::new(|| Mutex::new(HashMap::new()));
+
+/// Minimum interval between consecutive messages to the same WeChat user.
+const MIN_MSG_INTERVAL_MS: u64 = 1500;
+
+/// Wait if needed to respect the rate limit, then record the send time.
+async fn throttle(chat_id: &str) {
+    let now = tokio::time::Instant::now();
+    let sleep_ms = {
+        let mut map = LAST_SEND.lock().unwrap();
+        let delay = map.get(chat_id).and_then(|last| {
+            let elapsed = now.duration_since(*last);
+            if elapsed < Duration::from_millis(MIN_MSG_INTERVAL_MS) {
+                Some(Duration::from_millis(MIN_MSG_INTERVAL_MS) - elapsed)
+            } else {
+                None
+            }
+        });
+        // Record the expected send time now (before sleep), so concurrent
+        // callers also see the updated time and don't race.
+        map.insert(chat_id.to_string(), now);
+        delay
+    };
+    if let Some(ms) = sleep_ms {
+        tokio::time::sleep(ms).await;
+    }
+}
+
+/// Update rate-limit timestamp (without waiting) — used after each chunk.
+fn touch_rate_limit(chat_id: &str) {
+    LAST_SEND
+        .lock()
+        .unwrap()
+        .insert(chat_id.to_string(), tokio::time::Instant::now());
+}
+
 #[derive(Clone)]
 pub struct WechatChannel {
     name: String,
@@ -313,6 +351,9 @@ impl Channel for WechatChannel {
         let mut text_sent = false;
 
         if !text.is_empty() {
+            // Rate limit: ensure minimum interval between messages to the same user
+            throttle(&msg.chat_id).await;
+
             let chunks = split_text(&text, MAX_WECHAT_CHUNK_CHARS);
             if chunks.len() > 1 {
                 tracing::info!(
@@ -335,6 +376,8 @@ impl Channel for WechatChannel {
                         error
                     ))
                 })?;
+                // Update rate-limit timestamp so the next message or chunk respects the gap
+                touch_rate_limit(&msg.chat_id);
                 tracing::info!(
                     channel = %self.name,
                     chat_id = %msg.chat_id,