Mps Aspect Editor Menus And Keymaps

Reference Index

Start here — most common case: if you are not yet sure which artefact to build, read only references/landscape.md — its table routes you to the one further file you need (e.g. a keystroke on a cell → references/keymaps.md; a completion item → references/substitute-menus.md; overriding DELETE/BACKSPACE → references/action-maps.md).

• Open references/landscape.md when choosing which artefact to build — the master table of root concepts, attachment-point roles, file conventions, naming conventions, and the BaseConcept_TransformationMenu super-chain rule. Also covers the TransformationMenu_Default / _Named deprecation note (future merge into TransformationMenuImpl).
• Open references/action-maps.md when overriding standard cell actions (DELETE, BACKSPACE, SELECT_ALL, LEFT_TRANSFORM, RIGHT_TRANSFORM, …) — CellActionMapDeclaration fields, item structure, the Not_ActionMap example from Kaja, BACKSPACE auto-registration, the keyboard-deletable-annotation pattern (delete a node attribute from its label cell and reselect the host node), importing maps via CellActionMapImport/wildcard/by-action-id selectors, import rules (transitive, winner, no cycles, cross-language), SELECT_ALL customisation.
• Open references/keymaps.md when binding arbitrary keystrokes to a cell — CellKeyMapDeclaration fields, everyModel flag, CellKeyMapItem properties (keystroke, executeFunction, isApplicableFunction, description, caretPolicy, showInPopup, menuAlwaysShown), CastExpression_KeyMap template, modifiers string syntax (ctrl alt shift meta), caret-policy semantics, when to prefer an action map.
• Open references/transformation-menus.md when adding items to completion / context assistant / context actions tool / side transforms — section structure with locations + parts, the four TransformationLocation_* types, every menu part concept (Action, Group, Super, IncludeMenu, IncludeSubstituteMenu, SubMenu, Parameterized, WrapSubstituteMenu, PropertyMenu, ReferenceMenu, Placeholder), adapter parts (intention, refactoring, plugin Action), the Action blueprint with textFunction / executeFunction / canExecuteFunction / features (description text), parameterised parts with parameterObject, groups + variables (with the eager-evaluation gotcha), TransformationMenuContribution cross-language extension, cell-level attachment combining legacy menu + transformationMenu.
• Open references/substitute-menus.md when controlling what nodes are creatable at an AST position — default vs named, the five synthesised-default rules (sub-concepts, abstracts filtered, can-be-child, can-be-parent, smart-reference for 1:1), the "empty default suppresses" gotcha, all SubstituteMenuPart_* concepts (AddConcept, Concepts, Subconcepts, Group, IncludeMenu, Parameterized, Action, Wrapper, ReferenceScope, Placeholder), the Statement_SubstituteMenu JSON template, the Wrapper example wrapping Expression into ExpressionStatement.
• Open references/side-transforms.md when converting 1 typed + into 1 + <hole> — the right-transform JSON template on Expression, LEFT vs RIGHT semantics, the trick to also surface items in Ctrl+Space (either combine locations or include the menu from a completion section).
• Open references/legacy-cell-menus.md when dealing with cells that still have menu / postfixHint declarations — property values menu, postfix hints (with the verbatim splitByCamels example), primary replace-child / choose-referent, replace-node (custom node concept), generic items, cell menu reference, ref-presentation cell, and the presentation query in reference constraints deprecation warning.
• Open references/paste-and-copy.md when transforming pasted nodes or pre/post-processing copy/paste — PasteWrappers (in actions language) with sourceConcept/targetConcept/wrap function and the Expression → Statement example; CopyPasteHandlers with CopyPreProcessor (mutates copy, not original) and PastePostProcessor (re-resolves references with the LocalVariableReference example); triggering order (handlers → wrappers → graft).
• Open references/completion-styling.md when customising the look or priority of completion items — CompletionStyling selectors (items modifying concept instances vs items creating concept instances), styling attributes (bold/italic/strike/colour/hide/priority), sort order, ReturnStatementStyling / VariableReferencePriority examples, the global "Use completion styling" toggle.
• Open references/reference-presentation.md when changing how a reference looks resolved or in completion — ref. presentation cell on CellModel_RefCell, cell menu reference items, the recommended modern alternative (override the referenced concept's InlineEditorComponent or expose a getPresentation() behavior method).
• Open references/selection-and-deletion.md when selecting a node after a mutation or implementing two-step deletion — the select operation syntax (in:, cell:, selectionStart, selectionEnd), predefined cell values (FIRST, LAST, LAST_EDITABLE, MOST_RELEVANT), the ApproveDelete_Operation hook, the "node not already selected / not already approved" conditions, and the rule that custom delete actions must call node.approveDelete(editorContext) before mutating.
• Open references/json-blueprints.md when inserting any of these roots through MCP — copy-and-edit JSON for action map, keymap, transformation menu (default + side-transform), substitute menu (default + wrapper), paste wrapper, copy-paste handlers, completion styling. Each blueprint has a comment indicating where to inject BaseLanguage statement lists.
• Open references/wiring-tables.md when understanding the cell-to-aspect wiring — the cell menu / transformationMenu / substituteMenu / keyMap / actionMap mapping, when both are combined vs replaced, the name-driven discovery convention.
• Open references/real-examples.md when studying canonical implementations — jetbrains.mps.samples.Kaja (compact action-map + substitute menu + side-transform + style sheet), jetbrains.mps.baseLanguage (editor.mps ≈4 MB; actions.mps with paste wrappers; intentions.mps), with the mps_mcp_print_node workflow for cross-checking concept and role names.
• Open references/common-failures.md when a feature does not work — concept absent from completion (empty default substitute menu); side transform inserts the character; Delete doesn't fire (two-step deletion not approved); keymap item never fires; paste wrapper not triggered; transformation-menu action in completion but not Context Assistant; wrong role name in JSON (section/part/location/matchingTextFunction/applicableConcept); stale references after refactor (use FIX_REFERENCES); contribution defined in same language as the menu.