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/repo/test_lead_capture_repo.py

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+"""
+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.
+"""
+
+import pytest
+
+from app.repositories.lead_capture import LeadCaptureConfigRepository
+from app.models.schemas.lead_capture import LeadCaptureConfigUpdate, LeadField
+
+
+@pytest.fixture
+def repo(db):
+    return LeadCaptureConfigRepository(db)
+
+
+def test_get_by_agent_none_initially(repo, test_agent):
+    assert repo.get_by_agent(test_agent.id) is None
+
+
+def test_get_or_create_lazily_creates_off_config(repo, test_agent):
+    cfg = repo.get_or_create(test_agent.id)
+    assert cfg is not None
+    assert cfg.agent_id == test_agent.id
+    assert cfg.enabled is False
+    # Idempotent — a second call returns the same row.
+    again = repo.get_or_create(test_agent.id)
+    assert again.id == cfg.id
+
+
+def test_update_replaces_config(repo, test_agent):
+    repo.get_or_create(test_agent.id)
+    data = LeadCaptureConfigUpdate(
+        enabled=True,
+        require_consent=False,
+        guidance="Ask after pricing questions",
+        fields=[
+            LeadField(key="email", standard=True, enabled=True, required=True),
+            LeadField(key="custom_team", standard=False, enabled=True, label="Team size",
+                      options=["1-10", "11-50"]),
+        ],
+    )
+    updated = repo.update(test_agent.id, data)
+    assert updated.enabled is True
+    assert updated.require_consent is False
+    assert updated.guidance == "Ask after pricing questions"
+    keys = {f["key"] for f in (updated.fields or [])}
+    assert keys == {"email", "custom_team"}
+
+    # Persisted: a fresh fetch reflects the update.
+    fetched = repo.get_by_agent(test_agent.id)
+    assert fetched.enabled is True
+    assert len(fetched.fields) == 2