feat: 实现长消息分块发送功能，优化 WeChat 消息传递

src/channels/wechat.rs

@@ -5,7 +5,7 @@ use std::sync::{
     Arc,
     atomic::{AtomicBool, Ordering},
 };
-use std::time::UNIX_EPOCH;
+use std::time::{Duration, UNIX_EPOCH};
 
 use async_trait::async_trait;
 use futures_util::FutureExt;
@@ -313,15 +313,37 @@ impl Channel for WechatChannel {
         let mut text_sent = false;
 
         if !text.is_empty() {
-            self.bot.send(&msg.chat_id, &text).await.map_err(|error| {
-                ChannelError::SendError(format!("WeChat text send failed: {}", error))
+            let chunks = split_text(&text, MAX_WECHAT_CHUNK_CHARS);
+            if chunks.len() > 1 {
+                tracing::info!(
+                    channel = %self.name,
+                    chat_id = %msg.chat_id,
+                    total_chars = text.len(),
+                    chunk_count = chunks.len(),
+                    "WeChat: splitting long message into chunks"
+                );
+            }
+            for (i, chunk) in chunks.iter().enumerate() {
+                if i > 0 {
+                    tokio::time::sleep(Duration::from_millis(CHUNK_SEND_INTERVAL_MS)).await;
+                }
+                self.bot.send(&msg.chat_id, chunk).await.map_err(|error| {
+                    ChannelError::SendError(format!(
+                        "WeChat text send failed (chunk {}/{}): {}",
+                        i + 1,
+                        chunks.len(),
+                        error
+                    ))
                 })?;
                 tracing::info!(
                     channel = %self.name,
                     chat_id = %msg.chat_id,
-                content_len = text.len(),
+                    chunk = i + 1,
+                    total_chunks = chunks.len(),
+                    content_len = chunk.len(),
                     "WeChat text message sent"
                 );
+            }
             text_sent = true;
         }
 
@@ -356,6 +378,51 @@ impl Channel for WechatChannel {
     }
 }
 
+/// Split text into chunks suitable for WeChat delivery.
+/// Prefers splitting at paragraph breaks, then newlines, then sentence boundaries.
+const MAX_WECHAT_CHUNK_CHARS: usize = 2000;
+const CHUNK_SEND_INTERVAL_MS: u64 = 500;
+
+fn split_text(text: &str, limit: usize) -> Vec<String> {
+    if text.len() <= limit {
+        return vec![text.to_string()];
+    }
+    let mut chunks = Vec::new();
+    let mut remaining = text;
+    while !remaining.is_empty() {
+        if remaining.len() <= limit {
+            chunks.push(remaining.to_string());
+            break;
+        }
+        let end = remaining.floor_char_boundary(limit);
+        let window = &remaining[..end];
+        let cut = window
+            .rfind("\n\n")
+            .filter(|&i| i > end * 3 / 10)
+            .map(|i| i + 2)
+            .or_else(|| {
+                window
+                    .rfind('\n')
+                    .filter(|&i| i > end * 3 / 10)
+                    .map(|i| i + 1)
+            })
+            .or_else(|| {
+                window
+                    .rfind('。')
+                    .filter(|&i| i > end * 3 / 10)
+                    .map(|i| i + 3)
+            })
+            .unwrap_or(end);
+        chunks.push(remaining[..cut].to_string());
+        remaining = &remaining[cut..];
+    }
+    if chunks.is_empty() {
+        vec![String::new()]
+    } else {
+        chunks
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;