Extension Creator

Create AiderDesk extensions that extend functionality through events, commands, tools, agents, and modes.

When to Use

Use this skill when:

• Building a new AiderDesk extension
• Creating extension commands, tools, or event handlers
• Implementing the Extension interface
• Setting up extension metadata and documentation

Do not use when:

• Simply activating an existing extension
• Making general code changes unrelated to extensions
• Running tests or builds

Rules

Rule: Determine extension type first

When: Starting extension creation

Then: Check if extension needs npm dependencies or multiple files

If: Extension needs dependencies or multiple files

Then: Create folder extension in packages/extensions/extensions/my-extension/

If: Extension is simple with no dependencies

Then: Create single-file extension in packages/extensions/extensions/my-extension.ts

Rule: Implement Extension interface

When: Creating extension file

Then: Implement required methods from Extension interface

Must: Export metadata object with name, version, description, author, capabilities

Must: Export class as default

Never: Use @/ imports in extension files

Rule: Update extensions.json

When: Extension file created

Then: Add entry to packages/extensions/extensions.json

Must: Include id, name, description, file or folder path, type, capabilities

Must: Set hasDependencies: true for folder extensions

Rule: Update documentation

When: Extension is complete

Then: Add entry to docs-site/docs/extensions/examples.md table

Must: Include extension name, description, capabilities, and type

Rule: Use proper TypeScript config for folders

When: Creating folder extension

Then: Include tsconfig.json with module: ES2020+

Must: Include package.json with name, version, main, dependencies

Rule: Store config in extension directory

When: Extension needs persistent config

Then: Store config files in extension directory

Never: Store config outside extension directory

Process

1. Determine extension type (single-file or folder)
2. Create extension file or directory structure
3. Implement Extension interface methods
4. Export metadata and default class
5. Update extensions.json
6. Update docs-site/docs/extensions/examples.md
7. Verify with code-checker

Between steps 3 and 4:

• If extension needs config storage, create config.ts
• If extension needs logging, create logger.ts
• If extension needs constants, create constants.ts

Preconditions

Before using this skill, verify:

• Extension purpose and required capabilities are clear
• Extension type (single-file or folder) is determined
• Extension interface and types are understood

If any precondition fails:

• Review packages/extensions/extensions.d.ts
• Check references/event-types.md for event types
• Check references/command-definition.md for command structure

Postconditions

After completing this skill, verify:

• Extension implements Extension interface correctly
• Metadata export includes all required fields
• Default export is the extension class
• No @/ imports used
• extensions.json updated correctly
• docs-site/docs/extensions/examples.md updated
• Passes code-checker verification

Success metrics:

• Extension loads without errors
• Extension appears in extensions list
• Extension capabilities work as expected

Common Situations

Situation: Extension needs to handle events

Pattern:

• When: Extension needs to modify agent behavior
• Then: Implement event handler methods (onAgentStarted, onToolCalled, etc.)
• Return: Partial event object to modify behavior

Situation: Extension needs to register commands

Pattern:

• When: Extension provides slash commands
• Then: Implement getCommands() method
• Return: Array of CommandDefinition objects

Situation: Extension needs config storage

Pattern:

• Check: Extension needs persistent settings
• If yes: Create config.ts with loadConfig and saveConfig functions
• Store: Config files in extension directory

References

• packages/extensions/extensions.d.ts - Full Extension interface and types
• event-types.md - All event types and payloads
• command-definition.md - Command structure
• examples-gallery.md - Real extension examples
• extension-types.md - Single-file vs folder extensions

Assets

• templates/single-file.ts.template - Single-file template
• templates/folder-extension.template/ - Folder template