chore: create Multica handoff checkpoint

app/backend/features/mentor/agent.py

@@ -15,6 +15,11 @@ class MentorAgentError(RuntimeError):
     pass
 
 
+FOLLOW_UP_START = "<XIAOBAI_FOLLOW_UPS>"
+FOLLOW_UP_END = "</XIAOBAI_FOLLOW_UPS>"
+MAX_FOLLOW_UP_LENGTH = 80
+
+
 @dataclass(frozen=True)
 class MentorSkill:
     skill_id: str
@@ -185,6 +190,8 @@ def stream_with_mentor(
     base_url: str,
     model: str,
     timeout: int = 90,
+    *,
+    follow_ups: list[str] | None = None,
 ) -> Iterator[str]:
     if not api_key or not model:
         raise MentorAgentError("LLM API Key 或模型尚未配置。")
@@ -193,8 +200,10 @@ def stream_with_mentor(
     messages = [{"role": "system", "content": system_prompt}]
     messages.extend(history[-10:])
     messages.append({"role": "user", "content": question})
+    if follow_ups is not None:
+        follow_ups.clear()
     try:
-        yield from llm_transport.stream_chat_completion(
+        upstream = llm_transport.stream_chat_completion(
             api_key=api_key,
             base_url=base_url,
             model=model,
@@ -202,6 +211,7 @@ def stream_with_mentor(
             timeout=timeout,
             user_agent="XiaobaiReviewWeb/0.6",
         )
+        yield from _stream_answer_and_collect_follow_ups(upstream, follow_ups)
     except llm_transport.OpenAIEmptyResponseError as exc:
         raise MentorAgentError("问师模型未返回有效内容。") from exc
     except llm_transport.OpenAIHTTPError as exc:
@@ -223,6 +233,10 @@ def _build_system_prompt(skill: MentorSkill, market_context: dict[str, Any]) ->
 5. 优先回答用户真正的问题。市场分析通常按“判断、数据依据、思维模型下的应对、失效条件”组织；纯交易心理或方法问题可以自然回答，不强制套模板。
 6. 保留该 Skill 的核心心智模型和表达节奏，但不要复述身份履历，不要宣称自己就是真人，不攻击或贬低用户。
 7. 使用中文，信息密度高，避免空泛口号。引用数字时标明数据日期。
+8. 正文结束后必须输出2至3条与本轮问题和正文直接相关的追问。追问用于帮助用户继续核实条件、风险或失效边界，不得引入正文没有依据的新事实，不得给出无条件买卖指令。严格使用以下机器结构，不要放进Markdown代码块，结束标签后不要再输出文字：
+<XIAOBAI_FOLLOW_UPS>
+["追问一？","追问二？","追问三？"]
+</XIAOBAI_FOLLOW_UPS>
 
 网页市场数据：
 {context_json}
@@ -233,6 +247,67 @@ def _build_system_prompt(skill: MentorSkill, market_context: dict[str, Any]) ->
 """.strip()
 
 
+def _stream_answer_and_collect_follow_ups(
+    chunks: Iterator[str], follow_ups: list[str] | None
+) -> Iterator[str]:
+    buffer = ""
+    collecting = False
+    for raw_chunk in chunks:
+        chunk = str(raw_chunk or "")
+        if not chunk:
+            continue
+        buffer += chunk
+        if collecting:
+            continue
+        marker_index = buffer.find(FOLLOW_UP_START)
+        if marker_index >= 0:
+            if marker_index:
+                yield buffer[:marker_index]
+            buffer = buffer[marker_index + len(FOLLOW_UP_START):]
+            collecting = True
+            continue
+        overlap = _marker_prefix_overlap(buffer, FOLLOW_UP_START)
+        emit_length = len(buffer) - overlap
+        if emit_length:
+            yield buffer[:emit_length]
+            buffer = buffer[emit_length:]
+
+    if not collecting:
+        if buffer:
+            yield buffer
+        return
+    raw_follow_ups = buffer.split(FOLLOW_UP_END, 1)[0].strip()
+    parsed = _parse_follow_ups(raw_follow_ups)
+    if follow_ups is not None and len(parsed) >= 2:
+        follow_ups.extend(parsed)
+
+
+def _marker_prefix_overlap(value: str, marker: str) -> int:
+    max_length = min(len(value), len(marker) - 1)
+    for length in range(max_length, 0, -1):
+        if value.endswith(marker[:length]):
+            return length
+    return 0
+
+
+def _parse_follow_ups(payload: str) -> list[str]:
+    try:
+        values = json.loads(payload)
+    except (TypeError, json.JSONDecodeError):
+        return []
+    if not isinstance(values, list):
+        return []
+    result: list[str] = []
+    for value in values:
+        question = re.sub(r"\s+", " ", str(value or "")).strip()
+        if not question or len(question) > MAX_FOLLOW_UP_LENGTH or question in result:
+            continue
+        result.append(question)
+        if len(result) == 3:
+            break
+    return result
+
+
 def _parse_frontmatter(content: str) -> dict[str, str]:
     if not content.startswith("---"):
         return {}