MPS: Skill for Claude Code

MPS Editor Aspect — Menus, Keymaps and Actions

Loading companion skills

Companion names in this skill are lazy dependencies: load only those relevant to the current task. If this skill came from an MCP server, use the host's skill loader to resolve the companion's unique discovered entry URI on the same host-assigned originating server. If the host has no server-backed skill loader, stop and report that limitation; do not silently fall back to a filesystem copy. If this skill came from a filesystem catalog, load the named sibling from that same catalog at <skills-root>/<skill-name>/SKILL.md, even if remote skill loaders are also available. Do not invent a tool name or server endpoint.

This skill covers how the editor reacts to typing, keystrokes, completion, paste and context actions. Menus, keymaps and action maps are roots of jetbrains.mps.lang.editor in the language's editor model, next to the concept editors. Paste wrappers, copy-paste handlers and node factories are roots of jetbrains.mps.lang.actions in the actions model. Both aspect ids are case-sensitive, with no @ suffix: aspect-model-stereotypes.md. For cells, layouts and style sheets use mps-aspect-editor.

Critical Directives

• Decide whether to write the EditorTestCases first (mps-tests), and print the decision as one line of visible text before your first edit of an editor, actions or test model (right after loading this skill if you already edited other aspects), Test-first: yes — <reason> or Test-first: no — <reason> (it applies to every behaviour in this skill). It pays off when the behaviour is non-trivial (menus, side transforms, keys, deletion, paste, several interacting items) or only loosely described: a test fixes the description as an exact before/result tree and caret, and a run that fails before the change, for the reason you expect, is what makes the later green run evidence. Skip it for a trivial change (a label, a style, one obvious item) or when the project setup or the user forbids editor tests; then print the changed roots as PLAIN TEXT, run mps_mcp_check_root_node_problems, and say in your report that the behaviour was not exercised in an editor.
• Pick the artefact by the behaviour. Change what Delete does → action map. A new shortcut → keymap. Text typed next to a cell → side transform. What Ctrl+Space offers for a slot → substitute menu. A pasted node must change concept → paste wrapper. Table: references/landscape.md.
• Nothing is found by name. A TransformationMenu / SubstituteMenu whose type is MenuTypeDefault is the default for its conceptDeclaration. Named menus, action maps and keymaps act only where a cell references them (transformationMenu child, actionMap / keyMap references) or a menu includes them. The one exception is everyModel=true keymaps.
• Author menus as TransformationMenu / SubstituteMenu with a type child: MenuTypeDefault, or MenuTypeNamed whose name property holds the menu name (a root name is dropped). TransformationMenu_Default/_Named, SubstituteMenu_Default/_Named and IMenu_Default/_Named are deprecated: never author them.
• A default transformation menu replaces the inherited items for each location it has a section for. Put superconcepts menu (TransformationMenuPart_Super) once for every location the menu covers, unless you mean to drop the inherited items there. A Completion section without it removes concept replacement on existing nodes. A menu with only side-transform sections keeps completion.
• The cell's own node decides. Side transforms and completion on a cell use the menus of the node owning that cell (its transformationMenu first). Attach a menu or map to the cell the caret is on, unless that cell is a child's only visible cell (references/landscape.md). The edge cell of a child belongs to the child.
• Typing applies an item only on a unique strict match, i.e. the typed text equals the item's text (or a can substitute guard accepts it with strictly = true) and nothing else still matches. A prefix applies nothing; the IDE's auto-popup shows the menu, and a test needs Complete (references/side-transforms.md).
• Cells have no substituteMenu role. Reach a named substitute menu through include substitute menu in a transformation menu. An empty default substitute menu hides its concept from completion.
• Side-transform items are not in Ctrl+Space unless the section also lists TransformationLocation_Completion, or a Completion section includes the menu with location set.
• Keep data across a replacement with a NodeFactory that reads sampleNode (mps-aspect-actions). Completion items call it. Hand-written bodies: new initialized runs the factory and also pre-fills required children; plain new does neither (references/transformation-menus.md).
• Two-step deletion: if (node.approveDelete[in: editorContext, cell: <cellId>]) { return; } before mutating. The keyword cell needs an id (EditorCellId). Use action maps, not VK_DELETE keymaps, for DELETE / BACKSPACE.
• Implicit-parameter concepts differ per function kind (node in a menu ≠ in an action map ≠ in a keymap ≠ in a cell query; paste functions use lang.actions concepts; pattern is QueryFunctionParameter_pattern in transformation and substitute menus). Take them from the leaf file of the artefact, or from a printed corpus root; write bodies with mps-model-manipulation idioms.
• Role names: conceptDeclaration, type, sections, locations, parts, textFunction, executeFunction, canExecuteFunction. Resolve concepts with mps_mcp_get_concept_details, copy shapes from printed corpus roots (references/real-examples.md).
• After edits, run mps_mcp_check_root_node_problems, then rebuild the language (mps_mcp_alter_nodes MAKE). In a running editor, Ctrl+Alt+B on a completion item shows the menu chain that produced it.