add-designer-extension

name	add-designer-extension
description	Add a context menu item, new element, or association creation option to a foreign package, element, or association end. Covers packageExtension and elementExtension patterns.
argument-hint	[target element/package type name and what to add]

Add Designer Extension

[!TIP] Read more if you want to know about designer extensions, package/element extensions, mapping options, or context menu items:

• Conceptual Reference
• Workflow & Common Mistakes (To conserve tokens, avoid reading these files for simple or minor updates.)

Purpose

Extend an existing element, package, or association end from a foreign module by adding new context menu options (e.g. child element/association creation or mapping options).

Musts

1. Identify foreign target typeId via MCP find_designer_elements or generated C# SpecializationTypeId constants.
2. Link Designer Settings to foreign designer GUID (Domain: 6ab29b31-27af-4f56-a67c-986d82097d63, Services: 81104ae6-2bc5-4bae-b05a-f987b0372d81).
3. For Element Extensions, apply Type Reference Extension Settings (Mode = Inherit) and Extension Settings stereotypes.
4. Add all context menu options under a [context menu] child element.
5. Set type reference of Association Creation Option to target end of association settings.
6. Verify via get_designer_validation_errors and generated .designer.settings file.

Must Nots

1. Never guess or hardcode a type GUID from memory.
2. Never skip Mode = Inherit on Type Reference Extension Settings for element extensions.
3. Never edit .designer.settings directly (always change the Module Builder model).