test: 补充知识处理、检索与 Agent 回归用例

覆盖切块、向量检索、工具调用和历史预算；模型相关用例使用桩。

backend/tests/core/test_params.py

@@ -0,0 +1,43 @@
+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+from app.core.params import MAX_DB_INT, MAX_PAGE, DbIntId, PageNumber
+
+app = FastAPI()
+
+
+@app.get("/things/{thing_id}")
+def read_thing(thing_id: DbIntId, page: PageNumber = 1):
+    return {"thing_id": thing_id, "page": page}
+
+
+client = TestClient(app)
+
+
+def test_ids_the_database_can_hold_pass_through():
+    assert client.get(f"/things/{MAX_DB_INT}?page={MAX_PAGE}").json() == {"thing_id": MAX_DB_INT, "page": MAX_PAGE}
+
+
+def test_ids_and_pages_the_database_would_choke_on_are_422():
+    """Past Postgres INTEGER, or a page whose OFFSET overflows, the query itself
+    would fail with a 500; the request is refused up front instead."""
+    assert client.get(f"/things/{MAX_DB_INT + 1}").status_code == 422
+    assert client.get("/things/0").status_code == 422
+    assert client.get(f"/things/1?page={MAX_PAGE + 1}").status_code == 422
+    assert client.get("/things/1?page=0").status_code == 422