重组为 backend/clients/docs 三层结构，并清理 git 污染。

将后端迁入 backend/，完善根目录 .gitignore，删除误提交的 .mypy_cache 缓存文件。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_archive_persister.py

@@ -0,0 +1,102 @@
+"""ArchivePersister：指数退避、重试上限与 durable fallback 恢复。"""
+
+from __future__ import annotations
+
+import json
+from datetime import datetime, timezone
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
+
+from app.baked import pipeline as bp
+from app.domain.consumption import SurgeryConsumptionStored
+from app.repositories.surgery_results import SurgeryResultRepository
+from app.services.video.archive_persister import ArchivePersister
+
+
+class _AlwaysFailRepo(SurgeryResultRepository):
+    def __init__(self) -> None:
+        super().__init__()
+        self.calls = 0
+
+    async def save_final_result(self, session: AsyncSession, **kwargs: object) -> None:
+        self.calls += 1
+        raise RuntimeError("db down")
+
+
+def _detail(item_id: str = "纱布") -> SurgeryConsumptionStored:
+    return SurgeryConsumptionStored(
+        item_id=item_id,
+        item_name=item_id,
+        qty=1,
+        doctor_id="vision",
+        timestamp=datetime(2026, 4, 23, 12, 0, tzinfo=timezone.utc),
+        source="vision",
+    )
+
+
+@pytest.mark.asyncio
+async def test_persist_or_archive_writes_durable_fallback(
+    tmp_path,
+    sqlite_session_factory: async_sessionmaker[AsyncSession],
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    fallback_dir = tmp_path / "pending_archive"
+    monkeypatch.setattr(bp, "ARCHIVE_PERSIST_DURABLE_FALLBACK_DIR", str(fallback_dir))
+    repo = _AlwaysFailRepo()
+    persister = ArchivePersister(
+        repository=repo,
+        session_factory=sqlite_session_factory,
+    )
+    ok = await persister.persist_or_archive("abc123", [_detail("纱布")])
+    assert ok is False
+    path = fallback_dir / "abc123.json"
+    assert path.exists()
+    payload = json.loads(path.read_text(encoding="utf-8"))
+    assert payload["surgery_id"] == "abc123"
+    assert payload["details"][0]["item_id"] == "纱布"
+    assert persister.archived_details("abc123") is not None
+    got_async = await persister.archived_details_async("abc123")
+    assert got_async is not None
+    assert got_async[0].item_id == "纱布"
+
+
+@pytest.mark.asyncio
+async def test_recover_from_durable_fallback_reloads_pending_archive(
+    tmp_path,
+    sqlite_session_factory: async_sessionmaker[AsyncSession],
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    fallback_dir = tmp_path / "pending_archive"
+    fallback_dir.mkdir()
+    payload = {
+        "surgery_id": "recov01",
+        "saved_at": "2026-04-23T08:00:00+00:00",
+        "details": [
+            {
+                "item_id": "缝线",
+                "item_name": "缝线",
+                "qty": 1,
+                "doctor_id": "vision",
+                "timestamp": "2026-04-23T08:00:00+00:00",
+                "source": "vision",
+            }
+        ],
+    }
+    (fallback_dir / "recov01.json").write_text(json.dumps(payload, ensure_ascii=False), encoding="utf-8")
+    monkeypatch.setattr(bp, "ARCHIVE_PERSIST_DURABLE_FALLBACK_DIR", str(fallback_dir))
+    persister = ArchivePersister(
+        repository=SurgeryResultRepository(),
+        session_factory=sqlite_session_factory,
+    )
+    loaded = await persister.recover_from_durable_fallback()
+    assert loaded == 1
+    details = persister.archived_details("recov01")
+    assert details is not None
+    assert details[0].item_id == "缝线"
+
+    # 下一次 retry 应成功落库并清理内存 + durable 文件。
+    ok = await persister.try_persist_archive("recov01")
+    assert ok is True
+    assert persister.archived_details("recov01") is None
+    assert not (fallback_dir / "recov01.json").exists()