Obsidian Plugin Development Guidelines

You are assisting with Obsidian plugin development. Follow these comprehensive guidelines derived from the official Obsidian ESLint plugin rules, submission requirements, and best practices.

Getting Started

Quick Start Tool

For new plugin projects, an interactive boilerplate generator is available:

• Script: tools/create-plugin.js in the skill repository
• Slash command: /create-plugin for guided setup
• Generates minimal, best-practice boilerplate with no sample code
• Detects existing projects and only adds missing files
• All generated code follows these guidelines automatically

When to Suggest the Tool

Recommend the boilerplate generator when users:

• Ask "how do I create a new Obsidian plugin?"
• Want to start a new plugin project
• Need help setting up the basic structure
• Want to ensure they start with best practices

Core Principles

1. Memory Safety: Prevent memory leaks through proper resource management
2. Type Safety: Use proper type narrowing and avoid unsafe casts
3. API Best Practices: Follow Obsidian's recommended patterns
4. User Experience: Maintain consistency in UI/UX across plugins
5. Platform Compatibility: Ensure cross-platform support (including iOS)
6. Accessibility: Make all features keyboard and screen reader accessible

Quick Reference

Most Critical Rules (eslint-plugin-obsidianmd v0.1.9)

Submission & Naming:

1. Plugin ID: no "obsidian", can't end with "plugin" - Validation bot enforced
2. Plugin name: no "Obsidian", can't end with "Plugin" - Validation bot enforced
3. Plugin name: can't start with "Obsi" or end with "dian" - Validation bot enforced
4. Description: no "Obsidian", "This plugin", etc. - Validation bot enforced
5. Description must end with .?!) punctuation - Validation bot enforced

Memory & Lifecycle: 6. Use registerEvent() for automatic cleanup - Prevents memory leaks 7. Don't store view references in plugin - Causes memory leaks

Type Safety: 8. Use instanceof instead of type casting - Type safety for TFile/TFolder

UI/UX: 9. Use sentence case for all UI text - "Advanced settings" not "Advanced Settings" 10. Enforce sentence case in JSON locale files - ui/sentence-case-json (use recommendedWithLocalesEn) 11. Enforce sentence case in TS/JS locale modules - ui/sentence-case-locale-module 12. No "command" in command names/IDs - Redundant 13. No plugin ID/name in command IDs/names - Obsidian auto-namespaces 14. No default hotkeys - Avoid conflicts 15. Use .setHeading() for settings headings - Not manual HTML

API Best Practices: 16. Use Editor API for active file edits - Preserves cursor position 17. Use Vault.process() for background file mods - Prevents conflicts 18. Use normalizePath() for user paths - Cross-platform compatibility 19. Use Platform API for OS detection - Not navigator 20. Use requestUrl() instead of fetch() - Bypasses CORS restrictions 21. No console.log in onload/onunload in production - Pollutes console

Styling: 22. Use Obsidian CSS variables - Respects user themes 23. Scope CSS to plugin containers - Prevents style conflicts 24. Don't create <link> or <style> elements - Use styles.css file instead (no-forbidden-elements)

Accessibility (MANDATORY): 25. Make all interactive elements keyboard accessible - Accessibility required 26. Provide ARIA labels for icon buttons - Accessibility required 27. Define clear focus indicators - Use :focus-visible

Security & Compatibility: 28. Don't use innerHTML/outerHTML - Security risk (XSS) 29. Avoid regex lookbehind - iOS < 16.4 incompatibility

Code Quality: 30. Remove all sample/template code - MyPlugin, SampleModal, etc. 31. Don't mutate defaults with Object.assign - Use Object.assign({}, defaults, overrides) (object-assign) 32. Validate LICENSE copyright holder and year - Must not be "Dynalist Inc.", year must be current (validate-license)

Detailed Guidelines

For comprehensive information on specific topics, see the reference files:

Memory Management & Lifecycle

• Using registerEvent(), addCommand(), registerDomEvent(), registerInterval()
• Avoiding view references in plugin
• Not using plugin as component
• Proper leaf cleanup

Type Safety

• Using instanceof instead of type casting
• Avoiding any type
• Using const and let over var

UI/UX Standards

• Sentence case enforcement (TypeScript, JSON locale, TS/JS locale modules)
• recommendedWithLocalesEn config for locale file checks
• Command naming conventions (no "command", no plugin name, no plugin ID)
• Settings and configuration best practices

File & Vault Operations

• View access patterns
• Editor vs Vault API
• Atomic file operations
• File management
• Path handling

CSS Styling Best Practices

• Avoiding inline styles
• Using Obsidian CSS variables
• Scoping plugin styles
• Theme support
• Spacing and layout

Accessibility (A11y)

• Keyboard navigation (MANDATORY)
• ARIA labels and roles (MANDATORY)
• Tooltips and accessibility
• Focus management (MANDATORY)
• Focus visible styles (MANDATORY)
• Screen reader support (MANDATORY)
• Mobile and touch accessibility (MANDATORY)
• Accessibility checklist

Code Quality & Best Practices

• Removing sample code
• Security best practices
• Platform compatibility
• API usage best practices
• Async/await patterns
• DOM helpers

Plugin Submission Requirements

• Repository structure
• Submission process
• Semantic versioning
• Testing checklist

Essential Do's and Don'ts

Do's ✅

Memory & Lifecycle:

• Use registerEvent(), addCommand(), registerDomEvent(), registerInterval()
• Return views/components directly (don't store unnecessarily)

Type Safety:

• Use instanceof for type checking (not type casting)
• Use specific types or unknown instead of any
• Use const and let (not var)

API Usage:

• Use this.app (not global app)
• Use Editor API for active file edits
• Use Vault.process() for background file modifications
• Use FileManager.processFrontMatter() for YAML
• Use fileManager.trashFile() for deletions
• Use normalizePath() for user-defined paths
• Use Platform API for OS detection
• Use AbstractInputSuggest for autocomplete
• Use direct file lookups (not vault iteration)
• Use requestUrl() instead of fetch() for network requests

UI/UX:

• Use sentence case for all UI text (and locale JSON/TS files via recommendedWithLocalesEn)
• Use .setHeading() for settings headings
• Use Obsidian DOM helpers (createDiv(), createSpan(), createEl())
• Use window.setTimeout/setInterval with number type

Styling:

• Move all styles to CSS
• Use Obsidian CSS variables for all styling
• Scope CSS to plugin containers
• Support both light and dark themes via CSS variables
• Follow Obsidian's 4px spacing grid

Accessibility (MANDATORY):

• Make all interactive elements keyboard accessible
• Provide ARIA labels for icon buttons
• Define clear focus indicators using :focus-visible
• Use data-tooltip-position for tooltips
• Ensure minimum touch target size (44×44px)
• Manage focus properly in modals
• Test with keyboard navigation

Code Quality:

• Use async/await (not Promise chains)
• Remove all sample/template code
• Test on mobile (if not desktop-only)
• Follow semantic versioning
• Minimize console logging (no console.log in onload/onunload in production)

Don'ts ❌

Memory & Lifecycle:

• Don't store view references in plugin properties
• Don't pass plugin as component to MarkdownRenderer
• Don't detach leaves in onunload()

Type Safety:

• Don't cast to TFile/TFolder (use instanceof)
• Don't use any type
• Don't use var

API Usage:

• Don't use global app object
• Don't use Vault.modify() for active file edits
• Don't hardcode .obsidian path (use vault.configDir)
• Don't use navigator.platform/userAgent (use Platform API)
• Don't iterate vault when direct lookup exists
• Don't use fetch() (use requestUrl() instead)

UI/UX:

• Don't use Title Case in UI (use sentence case)
• Don't include "command" in command names/IDs
• Don't duplicate plugin ID in command IDs
• Don't set default hotkeys
• Don't create manual HTML headings (use .setHeading())
• Don't use "General", "settings", or plugin name in settings headings

Styling:

• Don't assign styles via JavaScript
• Don't hardcode colors, sizes, or spacing (use CSS variables)
• Don't use broad CSS selectors (scope to plugin)
• Don't manually switch themes (CSS variables adapt automatically)
• Don't create <link> or <style> elements (use styles.css file)

Security & Compatibility:

• Don't use innerHTML/outerHTML (XSS risk)
• Don't use regex lookbehind (iOS < 16.4 incompatibility)

Accessibility:

• Don't create inaccessible interactive elements
• Don't use icon buttons without ARIA labels
• Don't remove focus indicators without alternatives
• Don't make touch targets smaller than 44×44px

Code Quality:

• Don't use Promise chains (use async/await)
• Don't use document.createElement (use Obsidian helpers)
• Don't keep sample class names (MyPlugin, SampleModal, etc.)
• Don't use console.log in onload/onunload (pollutes console in production)
• Don't use Object.assign(defaultsVar, other) — mutates defaults; use Object.assign({}, defaults, other) instead
• Don't leave "Dynalist Inc." as LICENSE copyright holder or an outdated copyright year

When Reviewing/Writing Code

Use this checklist for code review and implementation:

1. Memory management: Are components and views properly managed?
2. Type safety: Using instanceof instead of casts?
3. UI text: Is everything in sentence case?
4. Command naming: No redundant words?
5. File operations: Using preferred APIs?
6. Mobile compatibility: No iOS-incompatible features?
7. Sample code: Removed all boilerplate?
8. Manifest: Correct version, valid structure?
9. Accessibility: Keyboard navigation, ARIA labels, focus indicators?
10. Testing: Can you use the plugin without a mouse?
11. Touch targets: Are all interactive elements at least 44×44px?
12. Focus styles: Using :focus-visible and proper CSS variables?

Common Patterns

Proper Command Registration

// ✅ CORRECT
this.addCommand({
  id: 'insert-timestamp',
  name: 'Insert timestamp',
  editorCallback: (editor: Editor, view: MarkdownView) => {
    editor.replaceSelection(new Date().toISOString());
  }
});

Safe Type Narrowing

// ✅ CORRECT
const file = this.app.vault.getAbstractFileByPath(path);
if (file instanceof TFile) {
  // TypeScript now knows it's a TFile
  await this.app.vault.read(file);
}

Keyboard Accessible Button

// ✅ CORRECT
const button = containerEl.createEl('button', {
  attr: {
    'aria-label': 'Open settings',
    'data-tooltip-position': 'top'
  }
});
button.setText('⚙️');

button.addEventListener('keydown', (e) => {
  if (e.key === 'Enter' || e.key === ' ') {
    e.preventDefault();
    performAction();
  }
});

Themed CSS

/* ✅ CORRECT */
.my-plugin-modal {
  background: var(--modal-background);
  color: var(--text-normal);
  padding: var(--size-4-4);
  border-radius: var(--radius-m);
  font-size: var(--font-ui-medium);
}

.my-plugin-button:focus-visible {
  outline: 2px solid var(--interactive-accent);
  outline-offset: 2px;
}

Additional Resources

• ESLint Plugin: eslint-plugin-obsidianmd (install for automatic checking)
• Obsidian API Docs: https://docs.obsidian.md
• Sample Plugin: https://github.com/obsidianmd/obsidian-sample-plugin
• Community: Obsidian Discord, Forum

Important Notes

• These guidelines are based on eslint-plugin-obsidianmd v0.1.9
• Rules marked as auto-fixable can be automatically corrected with ESLint's --fix flag
• Accessibility is NOT optional - all interactive elements must be keyboard accessible
• Always test on mobile devices if your plugin is not desktop-only

When helping with Obsidian plugin development, proactively apply these rules and suggest improvements based on these guidelines. Refer to the detailed reference files for comprehensive information on specific topics.