fix: stabilize AI coach chat against truncation and empty replies

Co-authored-by: Cursor <cursoragent@cursor.com>

manual_trading_hub/hub_ai/chat.py

@@ -7,6 +7,7 @@ from hub_ai.attachments import parse_chat_attachments
 from hub_ai.client import generate_text, model_label
 from hub_ai.config import (
     CHAT_CONTEXT_MAX_CHARS,
+    CHAT_HISTORY_MAX_CHARS_PER_MSG,
     CHAT_MAX_CONTINUATIONS,
     CHAT_MAX_HISTORY_TURNS,
     CHAT_MAX_OUTPUT_TOKENS,
@@ -25,17 +26,31 @@ from hub_ai.store import (
 )
 
 
-def _history_lines(messages: list[dict], max_turns: int = CHAT_MAX_HISTORY_TURNS) -> str:
+def _is_ai_error_reply(text: str) -> bool:
+    t = (text or "").strip()
+    return t.startswith("AI 调用失败") or t.startswith("AI 生成失败")
+
+
+def _history_lines(
+    messages: list[dict],
+    max_turns: int = CHAT_MAX_HISTORY_TURNS,
+    *,
+    max_chars_per_msg: int = 1500,
+) -> str:
     rows = [m for m in (messages or []) if m.get("role") in ("user", "assistant")]
     rows = rows[-max_turns * 2 :]
     lines = []
     for m in rows:
         role = "用户" if m.get("role") == "user" else "搭档"
-        content = m.get("content") or ""
+        content = str(m.get("content") or "").strip()
+        if m.get("role") == "assistant" and _is_ai_error_reply(content):
+            continue
         att = m.get("attachments") or []
         if att:
             names = "、".join(str(a.get("name") or "附件") for a in att[:3])
             content = f"{content} [附件: {names}]".strip()
+        if len(content) > max_chars_per_msg:
+            content = content[: max_chars_per_msg - 1].rstrip() + "…"
         lines.append(f"{role}：{content}")
     return "\n".join(lines)
 
@@ -79,7 +94,10 @@ def send_chat_message(
     day = ctx["trading_day"]
     session = ensure_active_session(trading_day=day)
     sid = session["id"]
-    history = _history_lines(session.get("messages") or [])
+    history = _history_lines(
+        session.get("messages") or [],
+        max_chars_per_msg=CHAT_HISTORY_MAX_CHARS_PER_MSG,
+    )
 
     append_chat_message(
         sid,
@@ -110,7 +128,7 @@ def send_chat_message(
         max_tokens=CHAT_MAX_OUTPUT_TOKENS,
         max_continuations=CHAT_MAX_CONTINUATIONS,
     )
-    if reply.startswith("AI 调用失败"):
+    if _is_ai_error_reply(reply):
         return {"ok": False, "msg": reply, "session_id": sid}
 
     session = append_chat_message(sid, "assistant", reply)