# kivy

Guides Cursor to write clean Kivy apps by separating UI into .kv files, integrating KivyMD components, and binding reactive properties.

- rule · `type=rule` · Cursor · ★ 3580
- Author: sanjeed5
- License: CC0-1.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/kivy.mdc
- Updated: 2026-05-19
- HTML: https://affpapa.org/en/nevibecode/rules/kivy

## What it does

The rule targets `**/*.py` files and stops Cursor from building imperative widget trees in Python. Layouts and visual elements belong in declarative `.kv` files. When building Material Design interfaces, the instructions specify KivyMD components such as `MDBoxLayout` and `MDTopAppBar`.

Project architecture follows a modular layout: screens go into `screens/` and custom components into `widgets/`. Shared styles reside in `kv/`. Reactive state relies on Kivy's `Property` classes like `StringProperty` or `NumericProperty`. Standard Python variables do not trigger UI bindings, so data updates require native Kivy properties.

Formatting conventions adhere to PEP 8 with a 79-character cap on docstrings and comments. Identifiers use single quotes, while visible UI text requires double quotes.

## Install

### Cursor (native platform)

**Manually: put the files in place**
- File: `.cursor/rules/kivy.mdc` — Frontmatter: description, globs, alwaysApply

### Claude Code

**Manually: put the files in place**
- File: `.claude/rules/kivy.md` — The paths frontmatter field limits the files: move globs from the source into paths

### Codex

**AGENTS.md**
- Codex reads AGENTS.md: paste the rule text there

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/instructions/kivy.instructions.md` — The applyTo field sets which files it applies to: move globs from the source into applyTo

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/rules/kivy.md`

### Cline

**Manually: put the files in place**
- File: `.clinerules/kivy.md`

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/sanjeed5/awesome-cursor-rules-mdc/tree/HEAD/rules-mdc/kivy.mdc

## When to use it
- move UI layout from Python files into declarative `.kv` files
- add Material Design widgets using the KivyMD package
- bind reactive data to UI elements with Kivy property types
- organize screens, custom widgets, and styles into dedicated directories

## Example prompts
- Build a KivyMD screen with a top app bar and a button.
- Refactor this Python widget layout into a separate `.kv` file.
- Add a `StringProperty` to update the label text when the button is clicked.

## Source text · kivy.mdc · CC0-1.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 475ee1e1d96b47ad.

BEGIN THIRD-PARTY FILE 475ee1e1d96b47ad
````text
---
description: Definitive guide for building modern, maintainable Kivy applications using best practices, focusing on KV language, KivyMD, and clear code organization.
globs: **/*.py
---
# Kivy Best Practices

This guide outlines the definitive best practices for developing Kivy applications. Adhere to these rules to ensure your codebase is maintainable, performant, and scales effectively.

## 1. Prioritize KV Language for UI Definition

**Opinion:** Always separate your UI definition from Python logic using Kivy Language (`.kv` files). This is the cornerstone of maintainable Kivy applications and enables declarative UI. Avoid building complex widget trees imperatively in Python.

**When to use:** For all visual components, layouts, bindings, and animations.

**❌ BAD (Imperative Python UI):**
```python
# main.py
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button

class BadApp(App):
    def build(self):
        layout = BoxLayout(orientation='vertical')
        button1 = Button(text='Click Me 1')
        button2 = Button(text='Click Me 2')
        layout.add_widget(button1)
        layout.add_widget(button2)
        return layout

BadApp().run()
```

**✅ GOOD (Declarative KV Language):**
```python
# main.py
from kivy.app import App
from kivy.lang import Builder

class GoodApp(App):
    def build(self):
        # Kivy automatically loads 'goodapp.kv' if not specified
        return Builder.load_file('goodapp.kv')

GoodApp().run()
```
```kv
# goodapp.kv
BoxLayout:
    orientation: 'vertical'
    Button:
        text: 'Click Me 1'
    Button:
        text: 'Click Me 2'
```

## 2. Leverage KivyMD for Material Design

**Opinion:** For modern, polished UIs, use KivyMD. It provides a rich set of Material Design components that integrate seamlessly with Kivy's KV language.

**When to use:** For all new UI development requiring a modern aesthetic.

**❌ BAD (Vanilla Kivy for complex components):**
```kv
# my_screen.kv
BoxLayout:
    # ... manually style a button to look like Material Design ...
    Button:
        background_color: 0.1, 0.5, 0.8, 1
        color: 1, 1, 1, 1
        padding: dp(16), dp(8)
        # ... many more properties ...
```

**✅ GOOD (KivyMD components):**
```kv
# my_screen.kv
MDBoxLayout: # Use MD layouts for consistency
    orientation: 'vertical'
    MDTopAppBar:
        title: "KivyMD App"
    MDButton:
        MDButtonText:
            text: "Material Button"
        on_release: app.root.ids.label.text = "Button pressed!"
    MDLabel:
        id: label
        text: "Hello KivyMD"
        halign: 'center'
```
```python
# main.py
from kivymd.app import MDApp
from kivy.lang import Builder

class MDExampleApp(MDApp):
    def build(self):
        # Load KV string directly for simple examples, or use Builder.load_file('my_screen.kv')
        return Builder.load_string("""
MDBoxLayout:
    orientation: 'vertical'
    MDTopAppBar:
        title: "KivyMD App"
    MDLabel:
        text: "Welcome to KivyMD!"
        halign: 'center'
""")

MDExampleApp().run()
```

## 3. Structure Your Project Modularly

**Opinion:** Organize your Kivy project into logical directories for maintainability and scalability. Separate KV files, Python logic, screens, and custom widgets.

**When to use:** For any project beyond a simple single-file example.

**❌ BAD (Monolithic structure):**
```
my_app/
├── main.py
├── all_screens_and_widgets.kv
├── images/
```

**✅ GOOD (Modular structure):**
```
my_app/
├── main.py
├── screens/
│   ├── home_screen.py
│   └── home_screen.kv
│   ├── settings_screen.py
│   └── settings_screen.kv
├── widgets/
│   ├── custom_button.py
│   └── custom_button.kv
├── kv/ # For global styles or shared rules
│   └── styles.kv
├── assets/
│   ├── images/
│   └── fonts/
```

## 4. Use Kivy Properties for Reactive UI
````
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