diff --git a/.dependencies.json b/.dependencies.json
new file mode 100644
index 0000000..990b225
--- /dev/null
+++ b/.dependencies.json
@@ -0,0 +1 @@
+{"docs/system_design/20260606123307.json": ["docs/prd/20260606123307.json"], "docs/task/20260606123307.json": ["docs/system_design/20260606123307.json"], "todo_cli/storage.py": ["docs/system_design/20260606123307.json", "docs/task/20260606123307.json"], "todo_cli/todo.py": ["docs/system_design/20260606123307.json", "docs/task/20260606123307.json"], "todo_cli/main.py": ["docs/system_design/20260606123307.json", "docs/task/20260606123307.json"]}
\ No newline at end of file
diff --git a/docs/prd/20260606123307.json b/docs/prd/20260606123307.json
new file mode 100644
index 0000000..25d8c20
--- /dev/null
+++ b/docs/prd/20260606123307.json
@@ -0,0 +1 @@
+{"Language":"zh_cn","Programming Language":"Python","Original Requirements":"创建一个Python命令行TODO应用，支持增删改查，数据存JSON文件","Project Name":"todo_cli","Product Goals":["提供简洁高效的命令行交互体验","确保数据持久化与可靠性","支持快速增删改查操作"],"User Stories":["作为用户，我希望能够通过命令行快速添加新的待办事项","作为用户，我希望能够查看所有待办事项及其完成状态","作为用户，我希望能够标记待办事项为已完成","作为用户，我希望能够删除不再需要的待办事项","作为用户，我希望能够修改已有待办事项的内容"],"Competitive Analysis":["Todo.txt CLI: 纯文本文件存储，支持标签和优先级，但无JSON格式","Taskwarrior: 功能强大的命令行任务管理，但学习曲线较陡","t: 轻量级TODO工具，使用JSON存储，但功能单一","GitHub Issues CLI: 与GitHub集成，不适合本地简单使用","Microsoft To Do CLI: 非官方，依赖云服务，离线不可用"],"Competitive Quadrant Chart":"quadrantChart\n    title \"命令行TODO工具竞争力分析\"\n    x-axis \"功能简单\" --> \"功能丰富\"\n    y-axis \"易用性低\" --> \"易用性高\"\n    quadrant-1 \"功能丰富且易用\"\n    quadrant-2 \"功能简单但易用\"\n    quadrant-3 \"功能简单且难用\"\n    quadrant-4 \"功能丰富但难用\"\n    \"Todo.txt CLI\": [0.3, 0.7]\n    \"Taskwarrior\": [0.8, 0.3]\n    \"t\": [0.2, 0.6]\n    \"GitHub Issues CLI\": [0.7, 0.4]\n    \"Microsoft To Do CLI\": [0.5, 0.5]\n    \"Our Target Product\": [0.4, 0.8]","Requirement Analysis":"本项目要求开发一个Python命令行TODO应用，核心功能包括增删改查（CRUD），数据以JSON文件形式持久化存储。用户通过命令行参数或交互式菜单操作。需要支持：添加任务（标题、描述、截止日期等可选字段）、列出所有任务（可筛选状态）、标记完成/未完成、删除任务、编辑任务内容。数据存储于本地JSON文件，需处理文件读写异常。命令行界面应清晰易用，提供帮助信息。","Requirement Pool":[["P0","实现添加待办事项功能，支持输入标题，可选描述和截止日期"],["P0","实现查看所有待办事项列表，显示ID、标题、状态、创建时间等"],["P0","实现删除待办事项功能，通过ID或索引删除"],["P0","实现修改待办事项功能，支持更新标题、描述、截止日期、状态"],["P1","实现数据持久化，使用JSON文件存储，支持自动加载和保存"]],"UI Design draft":"命令行界面，无图形UI。用户通过命令参数操作，例如：todo add \"任务标题\" -d \"描述\" -due 2025-01-01；todo list [--all|--done|--pending]；todo done <id>；todo delete <id>；todo edit <id> --title \"新标题\"。支持--help查看帮助。输出格式为表格或列表，清晰显示任务信息。","Anything UNCLEAR":"无"}
\ No newline at end of file
diff --git a/docs/requirement.txt b/docs/requirement.txt
new file mode 100644
index 0000000..a96f53a
--- /dev/null
+++ b/docs/requirement.txt
@@ -0,0 +1 @@
+创建一个Python命令行TODO应用，支持增删改查，数据存JSON文件
\ No newline at end of file
diff --git a/docs/system_design/20260606123307.json b/docs/system_design/20260606123307.json
new file mode 100644
index 0000000..6557235
--- /dev/null
+++ b/docs/system_design/20260606123307.json
@@ -0,0 +1 @@
+{"Implementation approach":"本项目使用Python标准库实现，无需第三方依赖。命令行参数解析采用argparse模块，数据持久化使用json模块，文件存储于用户主目录下的.todo_cli/todos.json。核心逻辑封装在TodoManager类中，提供增删改查方法。CLI接口通过TodoCLI类处理用户输入并调用TodoManager。数据模型TodoItem使用dataclass简化定义。整体设计遵循单一职责原则，确保代码简洁可维护。","File list":["main.py","todo.py","storage.py"],"Data structures and interfaces":"classDiagram\n    class TodoItem {\n        -int id\n        -str title\n        -str description\n        -str due_date\n        -bool completed\n        -str created_at\n        +__init__(id: int, title: str, description: str = \"\", due_date: str = \"\", completed: bool = False, created_at: str = \"\")\n        +to_dict() dict\n        +from_dict(data: dict) TodoItem\n    }\n    class Storage {\n        -str file_path\n        +__init__(file_path: str)\n        +load() list[dict]\n        +save(data: list[dict]) None\n    }\n    class TodoManager {\n        -list[TodoItem] items\n        -Storage storage\n        -int next_id\n        +__init__(storage: Storage)\n        +add(title: str, description: str = \"\", due_date: str = \"\") TodoItem\n        +list_all() list[TodoItem]\n        +list_by_status(completed: bool) list[TodoItem]\n        +mark_done(item_id: int) bool\n        +mark_undone(item_id: int) bool\n        +delete(item_id: int) bool\n        +edit(item_id: int, title: str = None, description: str = None, due_date: str = None, completed: bool = None) bool\n        +_load() None\n        +_save() None\n        +_find_by_id(item_id: int) TodoItem | None\n    }\n    class TodoCLI {\n        -TodoManager manager\n        -argparse.ArgumentParser parser\n        +__init__(manager: TodoManager)\n        +run(args: list[str] = None) None\n        +_setup_parser() None\n        +_handle_add(args) None\n        +_handle_list(args) None\n        +_handle_done(args) None\n        +_handle_delete(args) None\n        +_handle_edit(args) None\n    }\n    TodoCLI --> TodoManager\n    TodoManager --> Storage\n    TodoManager --> TodoItem\n    Storage ..> TodoItem : uses to_dict/from_dict\n","Program call flow":"sequenceDiagram\n    participant User as 用户\n    participant CLI as TodoCLI\n    participant Manager as TodoManager\n    participant Storage as Storage\n    participant File as JSON文件\n    User->>CLI: python main.py add \"任务标题\" -d \"描述\" -due 2025-01-01\n    CLI->>CLI: _setup_parser() 解析参数\n    CLI->>CLI: _handle_add(args)\n    CLI->>Manager: add(title, description, due_date)\n    Manager->>Manager: 生成新TodoItem，设置id=next_id\n    Manager->>Manager: 将item加入items列表\n    Manager->>Manager: _save()\n    Manager->>Storage: save([item.to_dict() for item in items])\n    Storage->>File: 写入JSON文件\n    File-->>Storage: 成功\n    Storage-->>Manager: None\n    Manager-->>CLI: 返回新TodoItem\n    CLI-->>User: 打印添加成功信息\n\n    User->>CLI: python main.py list\n    CLI->>CLI: _handle_list(args)\n    CLI->>Manager: list_all()\n    Manager->>Manager: 返回items列表\n    Manager-->>CLI: list[TodoItem]\n    CLI->>CLI: 格式化输出表格\n    CLI-->>User: 显示所有任务\n\n    User->>CLI: python main.py done 1\n    CLI->>CLI: _handle_done(args)\n    CLI->>Manager: mark_done(1)\n    Manager->>Manager: _find_by_id(1) -> item\n    Manager->>Manager: item.completed = True\n    Manager->>Manager: _save()\n    Manager-->>CLI: True\n    CLI-->>User: 打印标记成功\n\n    User->>CLI: python main.py delete 1\n    CLI->>CLI: _handle_delete(args)\n    CLI->>Manager: delete(1)\n    Manager->>Manager: _find_by_id(1) -> item\n    Manager->>Manager: 从items中移除\n    Manager->>Manager: _save()\n    Manager-->>CLI: True\n    CLI-->>User: 打印删除成功\n\n    User->>CLI: python main.py edit 1 --title \"新标题\" --description \"新描述\"\n    CLI->>CLI: _handle_edit(args)\n    CLI->>Manager: edit(1, title=\"新标题\", description=\"新描述\")\n    Manager->>Manager: _find_by_id(1) -> item\n    Manager->>Manager: 更新item属性\n    Manager->>Manager: _save()\n    Manager-->>CLI: True\n    CLI-->>User: 打印编辑成功\n","Anything UNCLEAR":"无"}
\ No newline at end of file
diff --git a/docs/task/20260606123307.json b/docs/task/20260606123307.json
new file mode 100644
index 0000000..a6cd450
--- /dev/null
+++ b/docs/task/20260606123307.json
@@ -0,0 +1 @@
+{"Required packages":[],"Required Other language third-party packages":[],"Logic Analysis":[["storage.py","Contains Storage class with load() and save() methods for JSON file persistence. No dependencies on other project files."],["todo.py","Contains TodoItem dataclass and TodoManager class. TodoManager depends on Storage for data persistence. Imports from storage.py."],["main.py","Contains TodoCLI class and main entry point. TodoCLI depends on TodoManager. Imports from todo.py."]],"Task list":["storage.py","todo.py","main.py"],"Full API spec":"","Shared Knowledge":"Data model: TodoItem with fields id, title, description, due_date, completed, created_at. Storage path: ~/.todo_cli/todos.json. All modules use Python standard library only.","Anything UNCLEAR":"无"}
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..e69de29
diff --git a/resources/competitive_analysis/20260606123307.mmd b/resources/competitive_analysis/20260606123307.mmd
new file mode 100644
index 0000000..aac3930
--- /dev/null
+++ b/resources/competitive_analysis/20260606123307.mmd
@@ -0,0 +1,14 @@
+quadrantChart
+    title "命令行TODO工具竞争力分析"
+    x-axis "功能简单" --> "功能丰富"
+    y-axis "易用性低" --> "易用性高"
+    quadrant-1 "功能丰富且易用"
+    quadrant-2 "功能简单但易用"
+    quadrant-3 "功能简单且难用"
+    quadrant-4 "功能丰富但难用"
+    "Todo.txt CLI": [0.3, 0.7]
+    "Taskwarrior": [0.8, 0.3]
+    "t": [0.2, 0.6]
+    "GitHub Issues CLI": [0.7, 0.4]
+    "Microsoft To Do CLI": [0.5, 0.5]
+    "Our Target Product": [0.4, 0.8]
\ No newline at end of file
diff --git a/resources/data_api_design/20260606123307.mmd b/resources/data_api_design/20260606123307.mmd
new file mode 100644
index 0000000..f166e1b
--- /dev/null
+++ b/resources/data_api_design/20260606123307.mmd
@@ -0,0 +1,50 @@
+classDiagram
+    class TodoItem {
+        -int id
+        -str title
+        -str description
+        -str due_date
+        -bool completed
+        -str created_at
+        +__init__(id: int, title: str, description: str = "", due_date: str = "", completed: bool = False, created_at: str = "")
+        +to_dict() dict
+        +from_dict(data: dict) TodoItem
+    }
+    class Storage {
+        -str file_path
+        +__init__(file_path: str)
+        +load() list[dict]
+        +save(data: list[dict]) None
+    }
+    class TodoManager {
+        -list[TodoItem] items
+        -Storage storage
+        -int next_id
+        +__init__(storage: Storage)
+        +add(title: str, description: str = "", due_date: str = "") TodoItem
+        +list_all() list[TodoItem]
+        +list_by_status(completed: bool) list[TodoItem]
+        +mark_done(item_id: int) bool
+        +mark_undone(item_id: int) bool
+        +delete(item_id: int) bool
+        +edit(item_id: int, title: str = None, description: str = None, due_date: str = None, completed: bool = None) bool
+        +_load() None
+        +_save() None
+        +_find_by_id(item_id: int) TodoItem | None
+    }
+    class TodoCLI {
+        -TodoManager manager
+        -argparse.ArgumentParser parser
+        +__init__(manager: TodoManager)
+        +run(args: list[str] = None) None
+        +_setup_parser() None
+        +_handle_add(args) None
+        +_handle_list(args) None
+        +_handle_done(args) None
+        +_handle_delete(args) None
+        +_handle_edit(args) None
+    }
+    TodoCLI --> TodoManager
+    TodoManager --> Storage
+    TodoManager --> TodoItem
+    Storage ..> TodoItem : uses to_dict/from_dict
diff --git a/resources/prd/20260606123307.md b/resources/prd/20260606123307.md
new file mode 100644
index 0000000..4ff3f8f
--- /dev/null
+++ b/resources/prd/20260606123307.md
@@ -0,0 +1,75 @@
+## Language
+
+zh_cn
+
+## Programming Language
+
+Python
+
+## Original Requirements
+
+创建一个Python命令行TODO应用，支持增删改查，数据存JSON文件
+
+## Project Name
+
+todo_cli
+
+## Product Goals
+
+- 提供简洁高效的命令行交互体验
+- 确保数据持久化与可靠性
+- 支持快速增删改查操作
+
+## User Stories
+
+- 作为用户，我希望能够通过命令行快速添加新的待办事项
+- 作为用户，我希望能够查看所有待办事项及其完成状态
+- 作为用户，我希望能够标记待办事项为已完成
+- 作为用户，我希望能够删除不再需要的待办事项
+- 作为用户，我希望能够修改已有待办事项的内容
+
+## Competitive Analysis
+
+- Todo.txt CLI: 纯文本文件存储，支持标签和优先级，但无JSON格式
+- Taskwarrior: 功能强大的命令行任务管理，但学习曲线较陡
+- t: 轻量级TODO工具，使用JSON存储，但功能单一
+- GitHub Issues CLI: 与GitHub集成，不适合本地简单使用
+- Microsoft To Do CLI: 非官方，依赖云服务，离线不可用
+
+## Competitive Quadrant Chart
+
+quadrantChart
+    title "命令行TODO工具竞争力分析"
+    x-axis "功能简单" --> "功能丰富"
+    y-axis "易用性低" --> "易用性高"
+    quadrant-1 "功能丰富且易用"
+    quadrant-2 "功能简单但易用"
+    quadrant-3 "功能简单且难用"
+    quadrant-4 "功能丰富但难用"
+    "Todo.txt CLI": [0.3, 0.7]
+    "Taskwarrior": [0.8, 0.3]
+    "t": [0.2, 0.6]
+    "GitHub Issues CLI": [0.7, 0.4]
+    "Microsoft To Do CLI": [0.5, 0.5]
+    "Our Target Product": [0.4, 0.8]
+
+## Requirement Analysis
+
+本项目要求开发一个Python命令行TODO应用，核心功能包括增删改查（CRUD），数据以JSON文件形式持久化存储。用户通过命令行参数或交互式菜单操作。需要支持：添加任务（标题、描述、截止日期等可选字段）、列出所有任务（可筛选状态）、标记完成/未完成、删除任务、编辑任务内容。数据存储于本地JSON文件，需处理文件读写异常。命令行界面应清晰易用，提供帮助信息。
+
+## Requirement Pool
+
+- ['P0', '实现添加待办事项功能，支持输入标题，可选描述和截止日期']
+- ['P0', '实现查看所有待办事项列表，显示ID、标题、状态、创建时间等']
+- ['P0', '实现删除待办事项功能，通过ID或索引删除']
+- ['P0', '实现修改待办事项功能，支持更新标题、描述、截止日期、状态']
+- ['P1', '实现数据持久化，使用JSON文件存储，支持自动加载和保存']
+
+## UI Design draft
+
+命令行界面，无图形UI。用户通过命令参数操作，例如：todo add "任务标题" -d "描述" -due 2025-01-01；todo list [--all|--done|--pending]；todo done <id>；todo delete <id>；todo edit <id> --title "新标题"。支持--help查看帮助。输出格式为表格或列表，清晰显示任务信息。
+
+## Anything UNCLEAR
+
+无
+
diff --git a/resources/seq_flow/20260606123307.mmd b/resources/seq_flow/20260606123307.mmd
new file mode 100644
index 0000000..5df6582
--- /dev/null
+++ b/resources/seq_flow/20260606123307.mmd
@@ -0,0 +1,54 @@
+sequenceDiagram
+    participant User as 用户
+    participant CLI as TodoCLI
+    participant Manager as TodoManager
+    participant Storage as Storage
+    participant File as JSON文件
+    User->>CLI: python main.py add "任务标题" -d "描述" -due 2025-01-01
+    CLI->>CLI: _setup_parser() 解析参数
+    CLI->>CLI: _handle_add(args)
+    CLI->>Manager: add(title, description, due_date)
+    Manager->>Manager: 生成新TodoItem，设置id=next_id
+    Manager->>Manager: 将item加入items列表
+    Manager->>Manager: _save()
+    Manager->>Storage: save([item.to_dict() for item in items])
+    Storage->>File: 写入JSON文件
+    File-->>Storage: 成功
+    Storage-->>Manager: None
+    Manager-->>CLI: 返回新TodoItem
+    CLI-->>User: 打印添加成功信息
+
+    User->>CLI: python main.py list
+    CLI->>CLI: _handle_list(args)
+    CLI->>Manager: list_all()
+    Manager->>Manager: 返回items列表
+    Manager-->>CLI: list[TodoItem]
+    CLI->>CLI: 格式化输出表格
+    CLI-->>User: 显示所有任务
+
+    User->>CLI: python main.py done 1
+    CLI->>CLI: _handle_done(args)
+    CLI->>Manager: mark_done(1)
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: item.completed = True
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印标记成功
+
+    User->>CLI: python main.py delete 1
+    CLI->>CLI: _handle_delete(args)
+    CLI->>Manager: delete(1)
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: 从items中移除
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印删除成功
+
+    User->>CLI: python main.py edit 1 --title "新标题" --description "新描述"
+    CLI->>CLI: _handle_edit(args)
+    CLI->>Manager: edit(1, title="新标题", description="新描述")
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: 更新item属性
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印编辑成功
diff --git a/resources/system_design/20260606123307.md b/resources/system_design/20260606123307.md
new file mode 100644
index 0000000..87db667
--- /dev/null
+++ b/resources/system_design/20260606123307.md
@@ -0,0 +1,126 @@
+## Implementation approach
+
+本项目使用Python标准库实现，无需第三方依赖。命令行参数解析采用argparse模块，数据持久化使用json模块，文件存储于用户主目录下的.todo_cli/todos.json。核心逻辑封装在TodoManager类中，提供增删改查方法。CLI接口通过TodoCLI类处理用户输入并调用TodoManager。数据模型TodoItem使用dataclass简化定义。整体设计遵循单一职责原则，确保代码简洁可维护。
+
+## File list
+
+- main.py
+- todo.py
+- storage.py
+
+## Data structures and interfaces
+
+classDiagram
+    class TodoItem {
+        -int id
+        -str title
+        -str description
+        -str due_date
+        -bool completed
+        -str created_at
+        +__init__(id: int, title: str, description: str = "", due_date: str = "", completed: bool = False, created_at: str = "")
+        +to_dict() dict
+        +from_dict(data: dict) TodoItem
+    }
+    class Storage {
+        -str file_path
+        +__init__(file_path: str)
+        +load() list[dict]
+        +save(data: list[dict]) None
+    }
+    class TodoManager {
+        -list[TodoItem] items
+        -Storage storage
+        -int next_id
+        +__init__(storage: Storage)
+        +add(title: str, description: str = "", due_date: str = "") TodoItem
+        +list_all() list[TodoItem]
+        +list_by_status(completed: bool) list[TodoItem]
+        +mark_done(item_id: int) bool
+        +mark_undone(item_id: int) bool
+        +delete(item_id: int) bool
+        +edit(item_id: int, title: str = None, description: str = None, due_date: str = None, completed: bool = None) bool
+        +_load() None
+        +_save() None
+        +_find_by_id(item_id: int) TodoItem | None
+    }
+    class TodoCLI {
+        -TodoManager manager
+        -argparse.ArgumentParser parser
+        +__init__(manager: TodoManager)
+        +run(args: list[str] = None) None
+        +_setup_parser() None
+        +_handle_add(args) None
+        +_handle_list(args) None
+        +_handle_done(args) None
+        +_handle_delete(args) None
+        +_handle_edit(args) None
+    }
+    TodoCLI --> TodoManager
+    TodoManager --> Storage
+    TodoManager --> TodoItem
+    Storage ..> TodoItem : uses to_dict/from_dict
+
+
+## Program call flow
+
+sequenceDiagram
+    participant User as 用户
+    participant CLI as TodoCLI
+    participant Manager as TodoManager
+    participant Storage as Storage
+    participant File as JSON文件
+    User->>CLI: python main.py add "任务标题" -d "描述" -due 2025-01-01
+    CLI->>CLI: _setup_parser() 解析参数
+    CLI->>CLI: _handle_add(args)
+    CLI->>Manager: add(title, description, due_date)
+    Manager->>Manager: 生成新TodoItem，设置id=next_id
+    Manager->>Manager: 将item加入items列表
+    Manager->>Manager: _save()
+    Manager->>Storage: save([item.to_dict() for item in items])
+    Storage->>File: 写入JSON文件
+    File-->>Storage: 成功
+    Storage-->>Manager: None
+    Manager-->>CLI: 返回新TodoItem
+    CLI-->>User: 打印添加成功信息
+
+    User->>CLI: python main.py list
+    CLI->>CLI: _handle_list(args)
+    CLI->>Manager: list_all()
+    Manager->>Manager: 返回items列表
+    Manager-->>CLI: list[TodoItem]
+    CLI->>CLI: 格式化输出表格
+    CLI-->>User: 显示所有任务
+
+    User->>CLI: python main.py done 1
+    CLI->>CLI: _handle_done(args)
+    CLI->>Manager: mark_done(1)
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: item.completed = True
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印标记成功
+
+    User->>CLI: python main.py delete 1
+    CLI->>CLI: _handle_delete(args)
+    CLI->>Manager: delete(1)
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: 从items中移除
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印删除成功
+
+    User->>CLI: python main.py edit 1 --title "新标题" --description "新描述"
+    CLI->>CLI: _handle_edit(args)
+    CLI->>Manager: edit(1, title="新标题", description="新描述")
+    Manager->>Manager: _find_by_id(1) -> item
+    Manager->>Manager: 更新item属性
+    Manager->>Manager: _save()
+    Manager-->>CLI: True
+    CLI-->>User: 打印编辑成功
+
+
+## Anything UNCLEAR
+
+无
+
diff --git a/todo_cli/main.py b/todo_cli/main.py
new file mode 100644
index 0000000..f4cadeb
--- /dev/null
+++ b/todo_cli/main.py
@@ -0,0 +1,213 @@
+"""Main entry point and CLI interface for the Todo CLI application.
+
+This module defines the TodoCLI class that handles command-line argument
+parsing and user interaction, as well as the main() function to start
+the application.
+"""
+
+import argparse
+import sys
+from typing import List, Optional
+
+from todo import TodoManager
+from storage import Storage
+
+
+class TodoCLI:
+    """Command-line interface for managing todo items.
+
+    Attributes:
+        manager: The TodoManager instance handling business logic.
+        parser: The ArgumentParser for parsing command-line arguments.
+    """
+
+    def __init__(self, manager: TodoManager) -> None:
+        """Initialize the CLI with a TodoManager.
+
+        Args:
+            manager: A TodoManager instance for data operations.
+        """
+        self.manager = manager
+        self.parser = argparse.ArgumentParser(
+            description="A simple CLI todo list manager."
+        )
+        self._setup_parser()
+
+    def _setup_parser(self) -> None:
+        """Configure subparsers for each command."""
+        subparsers = self.parser.add_subparsers(dest="command", help="Available commands")
+
+        # add command
+        add_parser = subparsers.add_parser("add", help="Add a new todo item")
+        add_parser.add_argument("title", type=str, help="Title of the task")
+        add_parser.add_argument("-d", "--description", type=str, default="",
+                                help="Description of the task")
+        add_parser.add_argument("-due", "--due_date", type=str, default="",
+                                help="Due date (e.g., 2025-01-01)")
+
+        # list command
+        list_parser = subparsers.add_parser("list", help="List all todo items")
+        list_parser.add_argument("-s", "--status", type=str, choices=["done", "pending"],
+                                 help="Filter by completion status")
+
+        # done command
+        done_parser = subparsers.add_parser("done", help="Mark a todo item as completed")
+        done_parser.add_argument("item_id", type=int, help="ID of the item to mark done")
+
+        # undone command
+        undone_parser = subparsers.add_parser("undone", help="Mark a todo item as not completed")
+        undone_parser.add_argument("item_id", type=int, help="ID of the item to mark undone")
+
+        # delete command
+        delete_parser = subparsers.add_parser("delete", help="Delete a todo item")
+        delete_parser.add_argument("item_id", type=int, help="ID of the item to delete")
+
+        # edit command
+        edit_parser = subparsers.add_parser("edit", help="Edit a todo item")
+        edit_parser.add_argument("item_id", type=int, help="ID of the item to edit")
+        edit_parser.add_argument("--title", type=str, default=None,
+                                 help="New title (leave unchanged if omitted)")
+        edit_parser.add_argument("--description", type=str, default=None,
+                                 help="New description (leave unchanged if omitted)")
+        edit_parser.add_argument("--due_date", type=str, default=None,
+                                 help="New due date (leave unchanged if omitted)")
+        edit_parser.add_argument("--completed", type=str, choices=["true", "false"],
+                                 default=None,
+                                 help="Set completion status (true/false)")
+
+    def run(self, args: Optional[List[str]] = None) -> None:
+        """Parse arguments and execute the corresponding command.
+
+        Args:
+            args: Command-line arguments (defaults to sys.argv[1:]).
+        """
+        parsed_args = self.parser.parse_args(args)
+
+        if parsed_args.command is None:
+            self.parser.print_help()
+            return
+
+        command_handlers = {
+            "add": self._handle_add,
+            "list": self._handle_list,
+            "done": self._handle_done,
+            "undone": self._handle_undone,
+            "delete": self._handle_delete,
+            "edit": self._handle_edit,
+        }
+
+        handler = command_handlers.get(parsed_args.command)
+        if handler:
+            handler(parsed_args)
+        else:
+            self.parser.print_help()
+
+    def _handle_add(self, args: argparse.Namespace) -> None:
+        """Handle the 'add' command.
+
+        Args:
+            args: Parsed arguments containing title, description, due_date.
+        """
+        item = self.manager.add(args.title, args.description, args.due_date)
+        print(f"Added todo item #{item.id}: {item.title}")
+
+    def _handle_list(self, args: argparse.Namespace) -> None:
+        """Handle the 'list' command.
+
+        Args:
+            args: Parsed arguments (may contain status filter).
+        """
+        if args.status == "done":
+            items = self.manager.list_by_status(True)
+        elif args.status == "pending":
+            items = self.manager.list_by_status(False)
+        else:
+            items = self.manager.list_all()
+
+        if not items:
+            print("No todo items found.")
+            return
+
+        # Print header
+        print(f"{'ID':<4} {'Title':<30} {'Completed':<10} {'Due Date':<12} {'Description'}")
+        print("-" * 80)
+        for item in items:
+            completed_str = "✓" if item.completed else "✗"
+            due = item.due_date if item.due_date else "-"
+            desc = item.description if item.description else ""
+            print(f"{item.id:<4} {item.title:<30} {completed_str:<10} {due:<12} {desc}")
+
+    def _handle_done(self, args: argparse.Namespace) -> None:
+        """Handle the 'done' command.
+
+        Args:
+            args: Parsed arguments containing item_id.
+        """
+        success = self.manager.mark_done(args.item_id)
+        if success:
+            print(f"Marked item #{args.item_id} as completed.")
+        else:
+            print(f"Error: Item #{args.item_id} not found.")
+
+    def _handle_undone(self, args: argparse.Namespace) -> None:
+        """Handle the 'undone' command.
+
+        Args:
+            args: Parsed arguments containing item_id.
+        """
+        success = self.manager.mark_undone(args.item_id)
+        if success:
+            print(f"Marked item #{args.item_id} as not completed.")
+        else:
+            print(f"Error: Item #{args.item_id} not found.")
+
+    def _handle_delete(self, args: argparse.Namespace) -> None:
+        """Handle the 'delete' command.
+
+        Args:
+            args: Parsed arguments containing item_id.
+        """
+        success = self.manager.delete(args.item_id)
+        if success:
+            print(f"Deleted item #{args.item_id}.")
+        else:
+            print(f"Error: Item #{args.item_id} not found.")
+
+    def _handle_edit(self, args: argparse.Namespace) -> None:
+        """Handle the 'edit' command.
+
+        Args:
+            args: Parsed arguments containing item_id and optional fields.
+        """
+        # Convert --completed string to bool if provided
+        completed = None
+        if args.completed is not None:
+            completed = args.completed.lower() == "true"
+
+        success = self.manager.edit(
+            args.item_id,
+            title=args.title,
+            description=args.description,
+            due_date=args.due_date,
+            completed=completed,
+        )
+        if success:
+            print(f"Updated item #{args.item_id}.")
+        else:
+            print(f"Error: Item #{args.item_id} not found.")
+
+
+def main() -> None:
+    """Application entry point.
+
+    Creates a Storage instance with default path, initializes TodoManager,
+    and runs the CLI.
+    """
+    storage = Storage()
+    manager = TodoManager(storage)
+    cli = TodoCLI(manager)
+    cli.run()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/todo_cli/storage.py b/todo_cli/storage.py
new file mode 100644
index 0000000..ed5764c
--- /dev/null
+++ b/todo_cli/storage.py
@@ -0,0 +1,66 @@
+"""Storage module for JSON file persistence.
+
+This module provides the Storage class that handles reading and writing
+todo items to a JSON file located at ~/.todo_cli/todos.json.
+"""
+
+import json
+import os
+from typing import List, Dict, Any
+
+
+class Storage:
+    """Handles persistent storage of todo items in a JSON file.
+
+    Attributes:
+        file_path: The absolute path to the JSON storage file.
+    """
+
+    def __init__(self, file_path: str = None) -> None:
+        """Initialize Storage with a file path.
+
+        If no file_path is provided, defaults to ~/.todo_cli/todos.json.
+
+        Args:
+            file_path: Optional custom path for the JSON file.
+        """
+        if file_path is None:
+            home_dir = os.path.expanduser("~")
+            self.file_path = os.path.join(home_dir, ".todo_cli", "todos.json")
+        else:
+            self.file_path = file_path
+
+    def load(self) -> List[Dict[str, Any]]:
+        """Load todo items from the JSON file.
+
+        Returns:
+            A list of dictionaries representing todo items.
+            Returns an empty list if the file does not exist or is corrupted.
+        """
+        if not os.path.exists(self.file_path):
+            return []
+
+        try:
+            with open(self.file_path, "r", encoding="utf-8") as f:
+                data = json.load(f)
+                if isinstance(data, list):
+                    return data
+                else:
+                    return []
+        except (json.JSONDecodeError, IOError):
+            return []
+
+    def save(self, data: List[Dict[str, Any]]) -> None:
+        """Save a list of todo item dictionaries to the JSON file.
+
+        Creates the directory structure if it does not exist.
+
+        Args:
+            data: A list of dictionaries representing todo items to persist.
+        """
+        directory = os.path.dirname(self.file_path)
+        if directory:
+            os.makedirs(directory, exist_ok=True)
+
+        with open(self.file_path, "w", encoding="utf-8") as f:
+            json.dump(data, f, indent=2, ensure_ascii=False)
diff --git a/todo_cli/todo.py b/todo_cli/todo.py
new file mode 100644
index 0000000..d175e80
--- /dev/null
+++ b/todo_cli/todo.py
@@ -0,0 +1,233 @@
+"""Todo item data model and manager module.
+
+This module defines the TodoItem dataclass and the TodoManager class
+that provides CRUD operations for todo items, backed by a Storage instance.
+"""
+
+import datetime
+from dataclasses import dataclass, field, asdict
+from typing import List, Optional, Dict, Any
+
+from storage import Storage
+
+
+@dataclass
+class TodoItem:
+    """Represents a single todo item.
+
+    Attributes:
+        id: Unique identifier for the item.
+        title: Short title of the task.
+        description: Optional detailed description.
+        due_date: Optional due date string (e.g., '2025-01-01').
+        completed: Whether the task is completed.
+        created_at: ISO-formatted creation timestamp.
+    """
+    id: int
+    title: str
+    description: str = ""
+    due_date: str = ""
+    completed: bool = False
+    created_at: str = field(default_factory=lambda: datetime.datetime.now().isoformat())
+
+    def to_dict(self) -> Dict[str, Any]:
+        """Convert the TodoItem to a dictionary for JSON serialization.
+
+        Returns:
+            A dictionary with all fields.
+        """
+        return asdict(self)
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any]) -> "TodoItem":
+        """Create a TodoItem from a dictionary (e.g., loaded from JSON).
+
+        Args:
+            data: Dictionary containing todo item fields.
+
+        Returns:
+            A new TodoItem instance.
+        """
+        return cls(
+            id=data["id"],
+            title=data["title"],
+            description=data.get("description", ""),
+            due_date=data.get("due_date", ""),
+            completed=data.get("completed", False),
+            created_at=data.get("created_at", ""),
+        )
+
+
+class TodoManager:
+    """Manages a collection of TodoItems with persistent storage.
+
+    Attributes:
+        items: List of current TodoItem objects.
+        storage: Storage instance for data persistence.
+        next_id: The next available ID for new items.
+    """
+
+    def __init__(self, storage: Storage) -> None:
+        """Initialize the manager with a Storage instance and load existing data.
+
+        Args:
+            storage: A Storage object for reading/writing JSON data.
+        """
+        self.storage = storage
+        self.items: List[TodoItem] = []
+        self.next_id: int = 1
+        self._load()
+
+    def add(self, title: str, description: str = "", due_date: str = "") -> TodoItem:
+        """Add a new todo item.
+
+        Args:
+            title: The title of the task.
+            description: Optional description.
+            due_date: Optional due date string.
+
+        Returns:
+            The newly created TodoItem.
+        """
+        item = TodoItem(
+            id=self.next_id,
+            title=title,
+            description=description,
+            due_date=due_date,
+        )
+        self.items.append(item)
+        self.next_id += 1
+        self._save()
+        return item
+
+    def list_all(self) -> List[TodoItem]:
+        """Return all todo items.
+
+        Returns:
+            A list of all TodoItem objects.
+        """
+        return self.items
+
+    def list_by_status(self, completed: bool) -> List[TodoItem]:
+        """Return todo items filtered by completion status.
+
+        Args:
+            completed: True for completed items, False for pending.
+
+        Returns:
+            A list of matching TodoItem objects.
+        """
+        return [item for item in self.items if item.completed == completed]
+
+    def mark_done(self, item_id: int) -> bool:
+        """Mark a todo item as completed.
+
+        Args:
+            item_id: The ID of the item to mark.
+
+        Returns:
+            True if the item was found and updated, False otherwise.
+        """
+        item = self._find_by_id(item_id)
+        if item is None:
+            return False
+        item.completed = True
+        self._save()
+        return True
+
+    def mark_undone(self, item_id: int) -> bool:
+        """Mark a todo item as not completed.
+
+        Args:
+            item_id: The ID of the item to mark.
+
+        Returns:
+            True if the item was found and updated, False otherwise.
+        """
+        item = self._find_by_id(item_id)
+        if item is None:
+            return False
+        item.completed = False
+        self._save()
+        return True
+
+    def delete(self, item_id: int) -> bool:
+        """Delete a todo item by its ID.
+
+        Args:
+            item_id: The ID of the item to delete.
+
+        Returns:
+            True if the item was found and removed, False otherwise.
+        """
+        item = self._find_by_id(item_id)
+        if item is None:
+            return False
+        self.items.remove(item)
+        self._save()
+        return True
+
+    def edit(
+        self,
+        item_id: int,
+        title: Optional[str] = None,
+        description: Optional[str] = None,
+        due_date: Optional[str] = None,
+        completed: Optional[bool] = None,
+    ) -> bool:
+        """Edit fields of an existing todo item.
+
+        Only fields that are not None will be updated.
+
+        Args:
+            item_id: The ID of the item to edit.
+            title: New title (or None to keep unchanged).
+            description: New description (or None to keep unchanged).
+            due_date: New due date (or None to keep unchanged).
+            completed: New completion status (or None to keep unchanged).
+
+        Returns:
+            True if the item was found and updated, False otherwise.
+        """
+        item = self._find_by_id(item_id)
+        if item is None:
+            return False
+        if title is not None:
+            item.title = title
+        if description is not None:
+            item.description = description
+        if due_date is not None:
+            item.due_date = due_date
+        if completed is not None:
+            item.completed = completed
+        self._save()
+        return True
+
+    def _load(self) -> None:
+        """Load todo items from storage and initialize next_id."""
+        raw_data = self.storage.load()
+        self.items = [TodoItem.from_dict(d) for d in raw_data]
+        if self.items:
+            max_id = max(item.id for item in self.items)
+            self.next_id = max_id + 1
+        else:
+            self.next_id = 1
+
+    def _save(self) -> None:
+        """Save current todo items to storage."""
+        data = [item.to_dict() for item in self.items]
+        self.storage.save(data)
+
+    def _find_by_id(self, item_id: int) -> Optional[TodoItem]:
+        """Find a todo item by its ID.
+
+        Args:
+            item_id: The ID to search for.
+
+        Returns:
+            The TodoItem if found, None otherwise.
+        """
+        for item in self.items:
+            if item.id == item_id:
+                return item
+        return None