✨ feat: 灵台引擎 Python 绑定与消息路径接入（WP-15/WP-03 交界）

- engine/bindings：nanobind 官方薄绑定包 hunjing-lingtai（LingtaiEngine RAII、HjStatus→LingtaiError 映射、HJ_ABI_VERSION 导出）；scikit-build-core 构建，直接编译引擎源码自包含
- backend 以 editable 路径依赖接入；typings/lingtai.pyi 类型存根（mypy strict 全绿）
- app/core/lingtai.py：懒初始化单例 + LingtaiUnavailable fail-closed（禁止宿主第二实现降级）
- 迁移 3：message.parser_version；post_message 的 markdown 输入经 hj_transform 规范化为 canonical blocks（展开 code/mermaid/math 并标注 parser_version，契约第 4 节）
- 测试 29 项全绿：消息展开、Python/C++ golden 字节一致、引擎注入失败时消息路径显式 500（fail-closed 验证）

backend/app/conversations/routes.py

@@ -72,6 +72,7 @@ async def post_message(
             branch_id=message.branch_id,
             role=message.role,
             content=message.content,
+            parser_version=message.parser_version,
             created_at=message.created_at.isoformat(),
         ),
         run=(

backend/app/conversations/schemas.py

@@ -44,6 +44,7 @@ class MessageOut(BaseModel):
     branch_id: str
     role: str
     content: list[dict[str, object]]
+    parser_version: str | None = None
     created_at: str
 
 

backend/app/conversations/service.py

@@ -14,6 +14,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.conversations.schemas import MessageIn
+from app.core import lingtai
 from app.core.ids import new_id
 from app.models import (
     AuditEvent,
@@ -122,15 +123,25 @@ async def replay_or_execute_message(
     conversation = await _require_conversation(db, domain_id, conversation_id)
     branch = await _get_default_branch(db, conversation.id)
 
-    blocks: list[dict[str, Any]] = [
-        {**b.model_dump(exclude_none=True), "id": new_id("block_"), "status": "completed"}
-        for b in body.content
-    ]
+    blocks: list[dict[str, Any]] = []
+    parser_version: str | None = None
+    for b in body.content:
+        if b.type == "markdown":
+            # 契约第 4 节：markdown 输入经确定性 parser 规范化为 canonical blocks
+            normalized = lingtai.transform_markdown(b.text)
+            parser_version = str(normalized["parser_version"])
+            blocks.extend(normalized["blocks"])
+        else:
+            blocks.append({**b.model_dump(exclude_none=True), "status": "completed"})
+    for block in blocks:
+        block["id"] = new_id("block_")
+        block.setdefault("status", "completed")
     message = Message(
         conversation_id=conversation.id,
         branch_id=branch.id,
         role="user",
         content=blocks,
+        parser_version=parser_version,
     )
     db.add(message)
     await db.flush()

backend/app/core/lingtai.py

@@ -0,0 +1,57 @@
+"""灵台引擎薄封装（Python 宿主接入，ADR-016）。
+
+- 懒初始化进程级单例；初始化或调用失败一律抛 LingtaiUnavailable，
+  由调用方 fail closed（禁止在宿主内用第二实现降级）。
+- 仅做类型转换与错误映射，不缓存权威状态、不复制业务语义。
+"""
+
+import json
+import threading
+from typing import Any
+
+import lingtai
+
+_lock = threading.Lock()
+_engine: lingtai.LingtaiEngine | None = None
+
+
+class LingtaiUnavailable(RuntimeError):
+    """引擎缺失、初始化失败或调用失败：依赖方必须显式失败。"""
+
+
+def get_engine() -> lingtai.LingtaiEngine:
+    global _engine
+    with _lock:
+        if _engine is None:
+            try:
+                _engine = lingtai.LingtaiEngine()
+            except Exception as exc:  # nanobind LingtaiError 等
+                raise LingtaiUnavailable(f"灵台引擎初始化失败：{exc}") from exc
+        return _engine
+
+
+def reset_engine() -> None:
+    """测试辅助：丢弃单例，下次访问重新初始化。"""
+    global _engine
+    with _lock:
+        _engine = None
+
+
+def transform_markdown(text: str) -> dict[str, Any]:
+    """Markdown → canonical ContentBlock（dict：parser_version + blocks）。"""
+    try:
+        engine = get_engine()
+    except LingtaiUnavailable:
+        raise
+    try:
+        raw = engine.transform_markdown(text)
+    except Exception as exc:
+        raise LingtaiUnavailable(f"灵台引擎调用失败：{exc}") from exc
+    parsed: dict[str, Any] = json.loads(raw)
+    for block in parsed["blocks"]:
+        block.setdefault("id", None)
+    return parsed
+
+
+def transform_version() -> str:
+    return str(lingtai.transform_version())

backend/app/models.py

@@ -191,6 +191,7 @@ class Message(Base):
     )
     role: Mapped[str] = mapped_column(String, nullable=False)
     content: Mapped[list[dict[str, Any]]] = mapped_column(JSONB, nullable=False)
+    parser_version: Mapped[str | None] = mapped_column(String, nullable=True)
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), nullable=False, server_default=func.now()
     )