refactor: enforce canonical backend imports

app/ARCHITECTURE.md

@@ -55,7 +55,11 @@ background scheduler
 
 Root modules such as `screener.py`, `tushare_client.py`, and `mentor_agent.py` are compatibility
 aliases to canonical modules. They contain no second implementation and remain only because
-the original public import surface is part of the preservation contract.
+the original public import surface is part of the preservation contract. Canonical backend
+modules must import other canonical modules directly rather than routing through these aliases.
+The remaining `api_access` import in `backend/application.py` and preserved lazy
+`sentiment_engine` import in the screener repository are registered transition boundaries;
+the root `database.py` remains the documented schema/composition anchor.
 
 ## Non-negotiable maintenance rules
 

app/backend/bootstrap/container.py

@@ -9,10 +9,10 @@ from backend.database.repositories import RepositoryBundle, build_repository_bun
 from backend.features.alerts import AlertService
 from backend.features.mentor.agent import MentorSkillRegistry
 from backend.features.review import TradeJournalService
+from backend.features.screener.engine import ScreenerEngine
 from backend.features.screener.tracking import StrategyTrackingService
 from backend.jobs import InProcessJobRunner, JobRegistry, SQLiteJobRunRepository
 from database import ReviewDatabase
-from screener import ScreenerEngine
 from backend.data.providers.ifind_client import IfindHttpClient
 from backend.data.realtime import WebRealtimeAggregator
 from backend.features.market.charts import MarketChartClient

app/backend/features/screener/compiler.py

@@ -4,7 +4,7 @@ import json
 from typing import Any
 
 from backend.llm import transport as llm_transport
-from screener import FACTOR_FIELDS, REGIMES
+from backend.features.screener.engine import FACTOR_FIELDS, REGIMES
 
 
 class LLMCompilerError(RuntimeError):

app/backend/features/screener/engine.py

@@ -8,11 +8,11 @@ from collections import defaultdict
 from datetime import datetime, timedelta
 from typing import Any
 
-from advanced_strategies import ADVANCED_CURATED_STRATEGIES
 from backend.data.numbers import finite_number as _number
+from backend.data.providers.tushare_client import TushareClient, TushareError
+from backend.features.screener.strategies import ADVANCED_CURATED_STRATEGIES
 from database import ReviewDatabase
 from backend.features.sentiment.engine import build_sentiment_history, latest_contiguous_history
-from tushare_client import TushareClient, TushareError
 
 
 REGIMES = {

app/config/architecture-inventory.json

@@ -289,7 +289,7 @@
     },
     {
       "path": "backend/features/screener/engine.py",
-      "bytes": 108394,
+      "bytes": 108434,
       "lines": 2206
     },
     {

app/sync_data.py

@@ -3,7 +3,8 @@ from __future__ import annotations
 import argparse
 from datetime import date
 
-from server import SERVICE, normalize_date
+from backend.application import SERVICE
+from backend.bootstrap.config import normalize_date
 
 
 def main() -> None:

app/tests/test_feature_boundaries.py

@@ -20,12 +20,6 @@ class FeatureBoundaryTests(unittest.TestCase):
         }
         violations = []
         for path in FEATURES.rglob("*.py"):
-            # The screener engine is an exact-preservation move of the legacy
-            # calculation module.  Its provider dependency is covered by the
-            # slice equivalence tests and will be addressed only after the
-            # behavior-preserving migration is complete.
-            if path.relative_to(FEATURES).as_posix() == "screener/engine.py":
-                continue
             tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
             for node in ast.walk(tree):
                 names = []
@@ -38,6 +32,53 @@ class FeatureBoundaryTests(unittest.TestCase):
                         violations.append(f"{path.relative_to(ROOT)} -> {name}")
         self.assertEqual(violations, [])
 
+    def test_backend_uses_root_compatibility_modules_only_at_declared_boundaries(self) -> None:
+        compatibility_modules = {
+            "advanced_strategies",
+            "alert_service",
+            "api_access",
+            "app_config",
+            "assistant_agent",
+            "chart_data_provider",
+            "heaven_agent",
+            "heaven_engine",
+            "ifind_client",
+            "llm_strategy",
+            "llm_stream",
+            "market_insights",
+            "mentor_agent",
+            "realtime_aggregator",
+            "screener",
+            "security",
+            "sentiment_engine",
+            "server",
+            "strategy_tracking",
+            "trade_journal",
+            "tushare_client",
+        }
+        allowed = {
+            "backend/application.py": {"api_access"},
+            "backend/features/screener/repository.py": {"sentiment_engine"},
+        }
+        violations = []
+        for path in (ROOT / "backend").rglob("*.py"):
+            relative = path.relative_to(ROOT).as_posix()
+            tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+            for node in ast.walk(tree):
+                names = []
+                if isinstance(node, ast.Import):
+                    names = [alias.name for alias in node.names]
+                elif isinstance(node, ast.ImportFrom) and node.module:
+                    names = [node.module]
+                for name in names:
+                    root_name = name.split(".")[0]
+                    if (
+                        root_name in compatibility_modules
+                        and root_name not in allowed.get(relative, set())
+                    ):
+                        violations.append(f"{relative} -> {name}")
+        self.assertEqual(violations, [])
+
     def test_legacy_service_modules_are_compatibility_exports_only(self) -> None:
         for filename in ("alert_service.py", "trade_journal.py", "strategy_tracking.py"):
             tree = ast.parse((ROOT / filename).read_text(encoding="utf-8"))

docs/governance/code-reduction.md

@@ -22,6 +22,7 @@
 | CR-02 | HTTP精确POST委托 | 27个端点重复使用“比较路径、调用无参数处理器、返回”三行分支 | 用公开/受保护两张显式映射统一委托，同时保留复杂路由的原控制流 | 已完成 |
 | CR-03 | 股票市场后缀转换 | Tushare业务与iFinD图表各保留一份完全相同的沪深京代码转换函数 | 图表复用`bootstrap/config.py::tushare_code`，只保留一份函数体 | 已完成 |
 | CR-04 | 数值归一化策略 | 四个业务模块分别保留两组完全相同的数值转换函数体 | 由`backend/data/numbers.py`集中拥有两种既有语义，消费者保留原局部别名 | 已完成 |
+| CR-05 | 根级兼容入口 | 正式后端仍有五处通过迁移兼容模块反向导入规范实现 | 正式代码改用规范路径；兼容入口只服务原公开导入契约 | 已完成 |
 
 ## CR-01验收口径
 
@@ -115,6 +116,29 @@
 本批基线为`xiaobai-reduction-03-market-symbol-20260801`；检查点为
 `xiaobai-reduction-04-numeric-normalization-20260801`。
 
+## CR-05验收口径
+
+- 逐项扫描根级Python入口、生产代码、测试、工具和动态导入；没有消费者或兼容责任的入口才能删除。
+- 规范后端不得经由`screener`、`advanced_strategies`、`tushare_client`或`server`兼容入口
+  间接访问已经归位的实现。
+- 所有根级模块继续保持原导入名称、导出对象及模块对象身份，既有启动命令和第三方维护脚本不受影响。
+- `api_access`、选股Repository的惰性`sentiment_engine`导入及根级`database.py`属于已登记边界，
+  分别留到HTTP、Repository阶段处理，不在本批跨边界修改。
+
+## CR-05结果
+
+- 审计确认21个根级兼容入口均有测试、工具、启动或原公开导入契约消费者，因此本批没有冒险删除文件。
+- 容器、策略编译器、选股引擎及数据同步命令的五处导入改为规范模块路径，正式代码不再通过四个根级
+  兼容模块反向进入实现；运行代码行数未增加。
+- 特性边界测试取消选股引擎旧例外，并新增全后端兼容导入门禁；只允许两项已登记过渡边界，后续代码
+  无法重新引入隐式根级依赖。
+- 候选321项、纯`app/`导出258项、24个JavaScript文件、API/架构注册表、Git空白检查和SQLite
+  完整性检查通过；本批不涉及页面、CSS或浏览器行为。
+- 本批不修改业务计算、策略公式、数据源、API、数据库、LLM、权限、前端或部署。
+
+本批基线为`xiaobai-reduction-04-numeric-normalization-20260801`；检查点为
+`xiaobai-reduction-05-compatibility-boundaries-20260801`。
+
 ## 人工验收记录
 
 - 2026-08-01：用户检查CR-02与CR-03运行结果，确认未发现明显异常。本记录仅表示本轮可见功能与