diff --git a/app/api/routers/task_runtime.py b/app/api/routers/task_runtime.py
index 7a49d88..2c2fcf8 100644
--- a/app/api/routers/task_runtime.py
+++ b/app/api/routers/task_runtime.py
@@ -1,8 +1,12 @@
+import logging
 from typing import Any
 
 from app import state
 
 
+logger = logging.getLogger(__name__)
+
+
 def set_task_stage(task_id: str, stage: str, logs: list[str], status: str = "processing") -> None:
     state.processing_tasks[task_id] = {
         "logs": logs.copy(),
@@ -29,4 +33,4 @@ def apply_history_retention_safely() -> None:
     try:
         state.apply_history_retention()
     except Exception as exc:
-        print(f"自动清理处理历史失败: {exc}")
+        logger.warning("Failed to apply history retention: %s", exc)
diff --git a/app/history.py b/app/history.py
index 16d0c34..995030c 100644
--- a/app/history.py
+++ b/app/history.py
@@ -2,6 +2,7 @@
 处理历史记录管理模块
 """
 import json
+import logging
 import shutil
 from pathlib import Path
 from datetime import datetime
@@ -12,6 +13,7 @@ from app.config import CACHE_DIR
 
 
 HISTORY_FILE = CACHE_DIR / "history.json"
+logger = logging.getLogger(__name__)
 
 
 @dataclass
@@ -69,9 +71,9 @@ class HistoryManager:
                     work_path.relative_to(cache_path)
                     shutil.rmtree(work_path)
                 except ValueError:
-                    print(f"警告: 尝试删除cache目录外的文件: {work_dir}")
+                    logger.warning("Skip deleting path outside cache directory: %s", work_dir)
         except Exception as e:
-            print(f"删除文件目录失败: {work_dir}, 错误: {e}")
+            logger.warning("Failed to delete work directory %s: %s", work_dir, e)
     
     def create(self, work_dir: Path, file_count: int, record_id: Optional[str] = None) -> HistoryRecord:
         """创建新的历史记录"""
@@ -159,7 +161,7 @@ class HistoryManager:
             logs = [line.strip() for line in content.split('\n') if line.strip()]
             return logs
         except Exception as e:
-            print(f"读取日志文件失败: {log_file}, 错误: {e}")
+            logger.warning("Failed to read history log file %s: %s", log_file, e)
             return []
     
     def delete(self, record_id: str) -> bool:
@@ -238,12 +240,12 @@ class HistoryManager:
                         item_path.unlink()
                 except ValueError:
                     # 路径不在cache目录内，跳过（安全保护）
-                    print(f"警告: 跳过cache目录外的文件: {item}")
+                    logger.warning("Skip path outside cache directory: %s", item)
                 except Exception as e:
                     # 单个文件/目录删除失败，继续处理其他文件
-                    print(f"删除失败: {item}, 错误: {e}")
+                    logger.warning("Failed to delete cache item %s: %s", item, e)
         except Exception as e:
             # 记录错误但不影响清空历史记录的操作
-            print(f"清空cache目录失败: {e}")
+            logger.warning("Failed to clear cache directory: %s", e)
         
         return count
diff --git a/app/processor.py b/app/processor.py
index 9a362f3..c1aa0c8 100644
--- a/app/processor.py
+++ b/app/processor.py
@@ -2,6 +2,7 @@
 数据处理核心模块
 """
 import chardet
+import logging
 import os
 import re
 import shutil
@@ -21,6 +22,9 @@ from app.database import DatabaseManager
 from app.utils.file_dates import DirectoryDateSelection, select_recent_items_by_directory
 
 
+logger = logging.getLogger(__name__)
+
+
 class ProcessLogger:
     """处理日志记录器"""
     
@@ -53,7 +57,7 @@ class ProcessLogger:
                     f.write(entry + "\n")
             except Exception as e:
                 # 如果写入失败，至少记录到内存
-                print(f"写入日志文件失败: {e}")
+                logger.warning("Failed to write process log file: %s", e)
         
         if self.callback:
             self.callback(entry)
diff --git a/docs/project_context.md b/docs/project_context.md
index 5152353..61008d4 100644
--- a/docs/project_context.md
+++ b/docs/project_context.md
@@ -830,3 +830,9 @@
 
 - “添加来源”按钮移动到主键表达式输入区下方右侧；点击后来源列表自动滚动到新增来源。
 - 验证：`frontend` `npm run build` 通过；构建产物已清理。
+
+## 2026-06-25：清理后端直接 print 诊断输出
+
+- `app/history.py`、`app/processor.py`、`app/api/routers/task_runtime.py` 中的异常诊断从直接 `print()` 改为模块级 `logging`，避免后台任务和历史清理在 stdout 中产生零散噪音，同时保留必要警告信息。
+- `app/main.py` 中的启动横幅 `print()` 保留，仍用于命令行直接启动时提示版本、配置更新时间和访问地址。
+- 验证：`CapacityReport\.venv\Scripts\python.exe -m compileall -q app` 通过；`frontend` `npx vue-tsc --noEmit --noUnusedLocals --noUnusedParameters` 通过。