feat: prepare RAG evidence and compatible chat requests

backend/app/api/routes/rag.py

@@ -0,0 +1,49 @@
+from uuid import UUID
+
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.models.rag import RagContext
+from app.schemas.catalog import Page
+from app.schemas.rag import ContextRead, PrepareContext
+from app.services.auth import CurrentSession, require_admin
+from app.services.catalog import page_result
+from app.services.rag import prepare_context
+
+router = APIRouter(prefix="/rag/contexts", tags=["rag"], dependencies=[Depends(require_admin)])
+
+
+@router.post("", response_model=ContextRead, status_code=201)
+def prepare(
+    payload: PrepareContext,
+    current: CurrentSession = Depends(require_admin),
+    db: Session = Depends(get_db),
+):
+    """准备并保存请求；不调用生成模型，不返回模型答案。"""
+    return prepare_context(db, payload, current.user.id)
+
+
+@router.get("", response_model=Page[ContextRead])
+def history(
+    page: int = Query(1, ge=1),
+    page_size: int = Query(20, ge=1, le=100),
+    db: Session = Depends(get_db),
+):
+    result = page_result(
+        db,
+        select(RagContext).order_by(RagContext.created_at.desc(), RagContext.id),
+        page,
+        page_size,
+    )
+    result["items"] = [row.response for row in result["items"]]
+    return result
+
+
+@router.get("/{context_id}", response_model=ContextRead)
+def read(context_id: UUID, db: Session = Depends(get_db)):
+    row = db.get(RagContext, str(context_id))
+    if row is None:
+        raise HTTPException(404, "上下文记录不存在")
+    return row.response