feat(services): assignment 6 skeleton - app service, field registry, in-memory repository

- fields_registry: 24 business keys in acd/human1/human2 groups with
  value_type, writable and SensitiveLevel metadata; strict bool/int
  parsing (no bool('0') trap); INTERNAL_FIELD_KEYS protection list
- repository: SessionRepository protocol + InMemorySessionRepository
  (idempotent delete; PostgreSQL swap-in is assignment 7)
- AccidentAppService: chat/set_info/get_info/delete_session share one
  business state - chat injects latest repository fields into the graph
  and writes back validated field diffs; set/get/delete make zero LLM
  calls and zero helper conversations (includeInputInfo accepted but
  unused); unknown get keys keep the '' JSON-empty-string contract,
  unknown set keys are rejected by whitelist
- ChatInput.injected_fields neutral contract extension; LangGraphBackend
  merges injected fields into graph input (set_info visible next chat)
- endpoints: thin layer - langgraph mode routes business state through
  the app service (fastgpt mode keeps the legacy path); delete cleans
  repository + graph checkpoint, idempotent
- tests: registry completeness (sfzmwh/sjwh/csbw included), app service
  combos with LLM-call spy, HTTP acceptance flow (set -> get -> chat ->
  groups -> delete -> no leak, idempotent re-delete)
- docs/assignment6-compat.md: behavior diff list vs FastGPT status quo
  and the audit backlog (arbitrary set_info key usage, stream formUpdate
  write-back, sensitive-field display boundary)

Verified: 200 unit tests (172 existing + 28 new)

test/api/test_assignment6_endpoints.py

@@ -0,0 +1,106 @@
+"""作业 6 验收演示的 HTTP 层组合测试。
+
+链路（对应计划作业 6）：创建会话 -> /set_info 写车牌 -> /get_info 读回
+-> /chat 继续核实 -> 分组读值 -> /delete_session -> 再读与再聊不泄漏。
+
+fake LLM（LLM_PROVIDER=fake）保证本测试离线可跑、零真实模型调用。
+"""
+
+import json
+
+import pytest
+from fastapi.testclient import TestClient
+
+from src.agent.llm import workflow_fake_llm
+from src.core.config import Config
+from src.main import app
+
+
+@pytest.fixture()
+def client(monkeypatch):
+    """langgraph 后端 + fake LLM 的测试客户端（lifespan 完整初始化）。"""
+    monkeypatch.setattr(Config, "AGENT_BACKEND", "langgraph")
+    monkeypatch.setattr(Config, "LLM_PROVIDER", "fake")
+
+    import src.agent.llm as llm_module
+
+    monkeypatch.setattr(
+        llm_module, "build_llm_service", lambda *a, **k: workflow_fake_llm()
+    )
+    with TestClient(app) as test_client:
+        yield test_client
+
+
+TS = "20261022120000"
+
+
+def test_assignment6_acceptance_flow(client):
+    session = "a6-acceptance-001"
+
+    # set_info 写入车牌（零 LLM：fake 未注入任何 responder，调用即报错）
+    response = client.post("/set_info", json={
+        "sessionId": session, "timeStamp": TS,
+        "key": "hphm1", "value": "苏B12345",
+    })
+    assert response.status_code == 200
+    assert response.json()["code"] == "200"
+
+    # get_info 单键读回
+    response = client.post("/get_info", json={
+        "sessionId": session, "timeStamp": TS, "key": "hphm1",
+    })
+    assert response.json()["value"] == '"苏B12345"'
+
+    # chat 使用业务状态继续（非流式，协议层解析 state 前缀）
+    response = client.post("/chat", json={
+        "sessionId": session, "timeStamp": TS,
+        "text": "我是刚才报警的驾驶员", "clientMode": "direct",
+    })
+    body = response.json()
+    assert body["code"] == "200"
+    assert body["nextStageCode"] in ("1001", "1002")
+
+    # 分组读值：三个分组齐全，未填字段为空串
+    response = client.post("/get_info", json={
+        "sessionId": session, "timeStamp": TS, "key": "all",
+    })
+    groups = json.loads(response.json()["value"])
+    assert set(groups) == {"acdinfo", "acdhuman1", "acdhuman2"}
+    assert groups["acdhuman1"]["hphm1"] == "苏B12345"
+    assert groups["acdhuman1"]["xm1"] == ""
+
+    # 未知 key 兼容：JSON 空串
+    response = client.post("/get_info", json={
+        "sessionId": session, "timeStamp": TS, "key": "no_such_key",
+    })
+    assert response.json()["value"] == '""'
+
+    # set_info 未知 key：白名单拒绝
+    response = client.post("/set_info", json={
+        "sessionId": session, "timeStamp": TS,
+        "key": "no_such_key", "value": "x",
+    })
+    assert response.json()["code"] == "500"
+
+    # 删除 -> 再读为空
+    response = client.request("DELETE", "/delete_session", json={
+        "sessionId": session, "timeStamp": TS,
+    })
+    assert response.json()["code"] == "200"
+    response = client.post("/get_info", json={
+        "sessionId": session, "timeStamp": TS, "key": "hphm1",
+    })
+    assert response.json()["value"] == '""'
+
+    # 重复删除幂等成功
+    response = client.request("DELETE", "/delete_session", json={
+        "sessionId": session, "timeStamp": TS,
+    })
+    assert response.json()["code"] == "200"
+
+    # 删除后再聊天：不注入旧业务数据，服务正常应答
+    response = client.post("/chat", json={
+        "sessionId": session, "timeStamp": TS,
+        "text": "新对话", "clientMode": "direct",
+    })
+    assert response.json()["code"] == "200"

test/services/test_app_service.py

@@ -0,0 +1,192 @@
+"""作业 6：应用服务四接口组合测试。
+
+验收演示对应（计划作业 6）：
+创建会话 -> set_info 写车牌 -> get_info 读回 -> chat 使用车牌继续核实
+-> 分组读值 -> 删除 -> 再读与再次聊天均不泄漏旧数据。
+
+spy 断言：set_info / get_info / delete_session 全程零模型调用。
+"""
+
+import json
+
+import pytest
+
+from src.backends.chat import ChatResult, TextDelta, FormUpdate
+from src.services.app_service import AccidentAppService, SET_INFO_INVALID_KEY_MSG
+from src.services.repository import InMemorySessionRepository
+
+
+class SpyBackend:
+    """记录调用的 ChatBackend 替身；form_update 模拟图产出的字段差量。"""
+
+    def __init__(self, form_update=None):
+        self.calls = []           # complete 收到的 ChatInput
+        self.stream_calls = []
+        self._form_update = form_update or {}
+        # 用调用次数当“模型调用”spy：真实 backend 每次 complete 至少一次 LLM
+        self.llm_calls = 0
+
+    async def complete(self, chat_input):
+        self.calls.append(chat_input)
+        self.llm_calls += 1
+        return ChatResult(
+            content="<state>1002</state>收到",
+            status_code=None,
+            form_update=dict(self._form_update),
+        )
+
+    async def stream(self, chat_input):
+        self.stream_calls.append(chat_input)
+        self.llm_calls += 1
+        yield TextDelta("<state>1002</state>")
+        if self._form_update:
+            yield FormUpdate(dict(self._form_update))
+        yield TextDelta("收到")
+
+
+def make_service(form_update=None):
+    backend = SpyBackend(form_update=form_update)
+    service = AccidentAppService(backend, InMemorySessionRepository())
+    return service, backend
+
+
+# ---- set/get：白名单、分组、外部表示 ----
+
+def test_set_then_get_single_key_roundtrip():
+    service, backend = make_service()
+    code, msg = service.set_info("s1", "hphm1", "苏B12345")
+    assert (code, msg) == ("200", "")
+    assert json.loads(service.get_info("s1", "hphm1")) == "苏B12345"
+    # set/get 零模型调用
+    assert backend.llm_calls == 0
+
+
+def test_get_groups_match_existing_contract():
+    service, _ = make_service()
+    service.set_info("s1", "ywrysw", "0")       # False
+    service.set_info("s1", "jdcsl", "0")        # int 0
+    service.set_info("s1", "xm2", "张三")
+
+    acd = json.loads(service.get_info("s1", "acdinfo"))
+    assert acd["ywrysw"] == "0"      # False -> "0"
+    assert acd["jdcsl"] == "0"       # int 0 -> "0"（内部类型不同）
+    assert acd["sgyy"] == ""         # 未知 -> 空串
+
+    human2 = json.loads(service.get_info("s1", "acdhuman2"))
+    assert human2["xm2"] == "张三"
+    assert human2["sfzmwh2"] == ""   # 全字段齐全，未填为空
+
+    all_groups = json.loads(service.get_info("s1", "all"))
+    assert set(all_groups) == {"acdinfo", "acdhuman1", "acdhuman2"}
+
+
+def test_get_unknown_key_returns_json_empty_string():
+    """兼容现状：未知 key 返回 JSON 空串 '""'。"""
+    service, _ = make_service()
+    service.set_info("s1", "hphm1", "苏B12345")
+    assert service.get_info("s1", "no_such_key") == '""'
+    assert service.get_info("ghost-session", "hphm1") == '""'
+
+
+def test_set_unknown_or_internal_key_rejected():
+    service, backend = make_service()
+    code, msg = service.set_info("s1", "no_such_key", "x")
+    assert code == "500" and msg == SET_INFO_INVALID_KEY_MSG
+    code, _ = service.set_info("s1", "stage_code", "1002")
+    assert code == "500"          # 内部字段保护
+    assert service.get_info("s1", "hphm1") == '""'   # 未被污染
+    assert backend.llm_calls == 0
+
+
+def test_set_rejects_unparsable_value():
+    service, _ = make_service()
+    code, msg = service.set_info("s1", "ywrysw", "maybe")
+    assert code == "500" and "无法解析" in msg
+
+
+# ---- chat：注入 + 写回 ----
+
+@pytest.mark.asyncio
+async def test_chat_sees_set_info_values_and_writes_back_patch():
+    """set_info 写入 -> chat 输入注入 -> 图差量写回 -> get_info 读到。"""
+    service, backend = make_service(form_update={"ywrysw": False})
+    service.set_info("s1", "hphm1", "苏B12345")
+    service.set_info("s1", "xm2", "李四")
+
+    result = await service.chat(
+        _input("s1", "我是刚才报警的驾驶员")
+    )
+    assert result.content == "<state>1002</state>收到"
+
+    # 图输入必须携带 repository 最新业务字段（车牌供核实使用）
+    injected = backend.calls[0].injected_fields
+    assert injected["person_fields"]["hphm1"] == "苏B12345"
+    assert injected["person_fields"]["xm2"] == "李四"
+
+    # 图产出的差量写回 repository，get_info 立即可读
+    assert json.loads(service.get_info("s1", "acdinfo"))["ywrysw"] == "0"
+    assert json.loads(service.get_info("s1", "hphm1")) == "苏B12345"
+
+
+@pytest.mark.asyncio
+async def test_chat_without_business_state_passes_no_injection():
+    service, backend = make_service()
+    await service.chat(_input("fresh-session", "你好"))
+    assert backend.calls[0].injected_fields is None
+
+
+@pytest.mark.asyncio
+async def test_stream_injects_fields_and_passthrough_events():
+    service, backend = make_service(form_update={"ywrysw": False})
+    service.set_info("s1", "xm1", "王五")
+    events = [
+        event async for event in service.stream(_input("s1", "继续办理"))
+    ]
+    kinds = [type(event).__name__ for event in events]
+    assert kinds == ["TextDelta", "FormUpdate", "TextDelta"]
+    assert backend.stream_calls[0].injected_fields["person_fields"]["xm1"] == "王五"
+
+
+# ---- delete：清理 + 幂等 ----
+
+@pytest.mark.asyncio
+async def test_delete_clears_business_state_and_is_idempotent():
+    drops = []
+
+    async def drop_checkpoint(session_id):
+        drops.append(session_id)
+
+    service, backend = make_service()
+    service.set_info("s1", "hphm1", "苏B12345")
+    await service.chat(_input("s1", "你好"))
+
+    await service.delete_session("s1", drop_checkpoint=drop_checkpoint)
+    assert drops == ["s1"]
+    # 再读为空、再聊天不注入旧数据
+    assert service.get_info("s1", "hphm1") == '""'
+    await service.chat(_input("s1", "还在吗"))
+    assert backend.calls[-1].injected_fields is None
+
+    # 重复删除固定行为：成功返回；checkpoint 清理会再次触发，
+    # 但缺失时静默容忍（幂等语义由 drop_checkpoint 内部保证）
+    await service.delete_session("s1", drop_checkpoint=drop_checkpoint)
+    assert drops == ["s1", "s1"]
+    assert backend.llm_calls == 2   # 两次 chat 各一次；set/get/delete 零调用
+
+
+@pytest.mark.asyncio
+async def test_delete_tolerates_missing_checkpoint():
+    async def missing(_session_id):
+        raise RuntimeError("no such thread")
+
+    service, _ = make_service()
+    service.set_info("s1", "xm1", "王五")
+    # checkpoint 不存在视为删除成功的一部分，不向上抛
+    await service.delete_session("s1", drop_checkpoint=missing)
+    assert service.get_info("s1", "xm1") == '""'
+
+
+def _input(session_id, text):
+    from src.backends.chat import ChatInput
+
+    return ChatInput(session_id=session_id, text=text, client_mode="direct")

test/services/test_fields_registry.py

@@ -0,0 +1,89 @@
+"""作业 6：字段注册表测试（分组完整性、类型/敏感级别、外部表示）。"""
+
+import pytest
+
+from src.services.fields_registry import (
+    FIELD_REGISTRY,
+    GROUP_KEYS,
+    INTERNAL_FIELD_KEYS,
+    FieldGroup,
+    SensitiveLevel,
+    parse_field_value,
+    to_external_string,
+)
+
+
+def test_registry_covers_all_three_groups():
+    """注册表完整覆盖 acd/human1/human2 三个分组（作业 6-3）。"""
+    assert set(GROUP_KEYS) == set(FieldGroup)
+    assert len(FIELD_REGISTRY) == 24
+    assert len(GROUP_KEYS[FieldGroup.ACD]) == 8
+    assert len(GROUP_KEYS[FieldGroup.HUMAN1]) == 8
+    assert len(GROUP_KEYS[FieldGroup.HUMAN2]) == 8
+
+
+def test_person_fields_include_full_set():
+    """人员字段必须包含 sfzmwh/sjwh/csbw，不能只迁姓名和号码。"""
+    for index in (1, 2):
+        group_keys = set(GROUP_KEYS[FieldGroup.HUMAN1 if index == 1 else FieldGroup.HUMAN2])
+        for suffix in ("xm", "hpzl", "hphm", "sfzmhm", "sfzmwh", "sjhm", "sjwh", "csbw"):
+            assert f"{suffix}{index}" in group_keys
+
+
+def test_registry_metadata_recorded():
+    """每个字段都记录类型、可写性、敏感级别（作业 6-4）。"""
+    for spec in FIELD_REGISTRY.values():
+        assert spec.value_type in (str, bool, int)
+        assert spec.writable is True
+        assert isinstance(spec.sensitive, SensitiveLevel)
+        assert spec.description
+
+
+def test_sensitive_levels_assigned():
+    """证件号/手机号 sensitive，姓名 personal，其余 public。"""
+    assert FIELD_REGISTRY["sfzmhm1"].sensitive is SensitiveLevel.SENSITIVE
+    assert FIELD_REGISTRY["sjhm2"].sensitive is SensitiveLevel.SENSITIVE
+    assert FIELD_REGISTRY["xm1"].sensitive is SensitiveLevel.PERSONAL
+    assert FIELD_REGISTRY["hphm1"].sensitive is SensitiveLevel.PUBLIC
+
+
+@pytest.mark.parametrize("raw,expected", [
+    ("1", True), ("true", True), ("是", True),
+    ("0", False), ("false", False), ("否", False),
+])
+def test_parse_bool_explicit(raw, expected):
+    assert parse_field_value(FIELD_REGISTRY["ywrysw"], raw) is expected
+
+
+@pytest.mark.parametrize("bad", ["", "maybe", "2", "有吧"])
+def test_parse_bool_rejects_ambiguous(bad):
+    """模糊值必须拒绝——保留 空/False/0/未知 的区分能力。"""
+    with pytest.raises(ValueError):
+        parse_field_value(FIELD_REGISTRY["ywrysw"], bad)
+
+
+def test_parse_int_and_str():
+    assert parse_field_value(FIELD_REGISTRY["jdcsl"], "2") == 2
+    assert parse_field_value(FIELD_REGISTRY["jdcsl"], "0") == 0
+    with pytest.raises(ValueError):
+        parse_field_value(FIELD_REGISTRY["jdcsl"], "两辆")
+    assert parse_field_value(FIELD_REGISTRY["hphm1"], "苏B12345") == "苏B12345"
+
+
+def test_external_string_representation():
+    """对外序列化：True->1，False->0，None->空串；内部仍区分 False 与 0。"""
+    assert to_external_string(True) == "1"
+    assert to_external_string(False) == "0"
+    assert to_external_string(0) == "0"
+    assert to_external_string(None) == ""
+    assert to_external_string("苏B12345") == "苏B12345"
+    # 内部存储不混淆：False 是 bool、0 是 int
+    assert parse_field_value(FIELD_REGISTRY["ywrysw"], "0") is False
+    assert parse_field_value(FIELD_REGISTRY["jdcsl"], "0") == 0
+    assert isinstance(parse_field_value(FIELD_REGISTRY["jdcsl"], "0"), int)
+
+
+def test_internal_field_protection_listed():
+    """图内部键登记在保护清单中，set_info 白名单不会收录它们。"""
+    for key in INTERNAL_FIELD_KEYS:
+        assert key not in FIELD_REGISTRY