MPS

Use when defining or editing MPS intentions (the Alt+Enter context-action aspect) — adding `IntentionDeclaration` roots, parameterized or surround-with variants, description/isApplicable/execute blocks, child-filter functions, factory-initialized AST splicing, or debugging why an intention is not offered. Lives in the language's `intentions` model and uses `jetbrains.mps.lang.intentions`.

Use when defining or modifying MPS generators — author a generator module, add or edit root/reduction/weaving/pattern mapping rules, attach template macros ($COPY_SRC, $LOOP, $IF, $PROPERTY, $REF, $SWITCH, $MAP_SRC, $WEAVE, $INSERT, $LABEL, $TRACE, $VAR), wire mapping labels, build template switches, write pre/post mapping scripts, navigate `genContext`, or debug "rule didn't fire", missing references, empty output, infinite reduction loops, and generated-Java compile failures.

Use when defining or modifying an MPS generation plan — explicit ordering of generators, checkpoints for cross-model reference resolution, forks for parallel branches, IncludePlan composition, conditional PlanContribution activation, ParameterEquals/ConceptListSelector fork selectors, and InitModelAttributes for targetFacet routing. Apply when working with @genplan models, the jetbrains.mps.lang.generator.plan language, attaching plans via DevKits or the Custom generation facet, or debugging cross-model mapping label resolution.

Use when creating or changing MPS editor definitions — the overall workflow from scaffolding a `ConceptEditorDeclaration` through componentizing reusable `EditorComponentDeclaration`s, refining cell models and cell layouts, applying style sheets and indent-layout style items, wiring smart references, leveraging inheritance via super-concepts and interfaces, inspecting (`print_node_json`, `show_node_representation`) and validating (`check_root_node_problems`). Covers `jetbrains.mps.lang.editor` cell models (`CellModel_RefNode`/`CellModel_RefNodeList`/`CellModel_RefCell`/`CellModel_Property`/`CellModel_Constant`), layout choices, and JSON blueprints for common editor shapes. For the non-layout side (action maps, keymaps, transformation/substitute menus) use `mps-aspect-editor-menus-and-keymaps`.

Use when authoring the **non-layout** parts of the MPS editor aspect — what happens when the user types, presses a key, triggers completion, pastes, or invokes a context action. Covers action maps (`CellActionMapDeclaration`), cell keymaps (`CellKeyMapDeclaration`), transformation menus (`TransformationMenu_Default` / `_Named` / `_Contribution`), substitute menus (`SubstituteMenu_Default` / `SubstituteMenu` / contributions), side transforms (LEFT/RIGHT), legacy cell menus, paste wrappers and copy-paste handlers (in the actions language), completion styling, reference presentation, two-step deletion, and the editor selection API. Trigger terms: `actionMap`, `keyMap`, `delete_action_id`, `transformationMenu`, `substituteMenu`, `Ctrl+Space`, `Ctrl+Alt+B`, side transform, paste wrapper, completion styling, `PasteWrappers`, `CopyPasteHandlers`. For the **layout** side (cells, layouts, style sheets) use `mps-aspect-editor` instead.

Use when defining or debugging MPS dataflow builders for a concept — control/data flow declarations that drive reachability analysis and variable-use checking. Covers DataFlowBuilderDeclaration, BuilderBlock, emit instructions (code for, jump, ifjump, label, read, write, ret, mayBeUnreachable), positions (AfterPosition, BeforePosition, LabelPosition), the jetbrains.mps.lang.dataFlow language, the NodeParameter implicit, BL+smodel usage inside builder bodies, and IBuilderMode for advanced analyses such as nullable/non-null tracking.

Use when defining or editing MPS language constraints — property validators / setters / getters, referent search scopes (imperative or inherited via `ScopeProvider.getScope`), `referentSetHandler` side effects, default-scope blocks, `canBeChild` / `canBeParent` / `canBeAncestor` / `canBeRoot` placement rules, `defaultConcreteConcept` for abstract concepts, `set <read-only>` and `{name}` aliasing, and scope helpers (`SimpleRoleScope`, `ListScope`, `CompositeScope`, `HidingByNameScope`). Reach for this skill whenever the task involves authoring or modifying `<lang>/languageModels/constraints.mps`.

Use when defining or editing MPS `ConceptBehavior` — per-concept methods (non-virtual / virtual / abstract / static / virtual static), constructors, virtual dispatch (MRO), super and interface-default calls (`super<Interface>.method`), overriding methods from `lang.core.behavior` interfaces such as `ScopeProvider.getScope` / `INamedConcept.getName` / `BaseConcept.getPresentation`, calling sibling methods (`LocalBehaviorMethodCall`) and behavior methods from other aspects via `node.method(...)`. Reach for this skill whenever the task involves authoring or modifying `<lang>/languageModels/behavior.mps`.

Use when defining or editing MPS node factories (the "actions" aspect) — `NodeFactories` roots, per-concept `NodeFactory` setup functions that initialize a freshly created node and optionally copy data from a replaced `sampleNode`, plus the actions aspect's `CopyPasteHandlers` and `PasteWrappers` roots. Reach for this skill when a substitution, side transform, completion replacement, or `add new initialized(...)` should preserve fields from the node it is replacing, or when defaults set in a constructor are not enough.

Wire MPS module and model dependencies, used languages, used devkits, extended languages, runtime solutions, accessory models, and language/dependency versions. Use when adding/removing module dependencies, importing languages or devkits into a model, declaring runtime solutions, or shipping accessory content visible to consumers without explicit import.

Debugging techniques and tools for IntelliJ development. Use when debugging IDE issues or investigating failures.

Use this skill whenever the user asks to commit changes, write or fix a commit message, amend or rename a commit, or do a workflow that includes committing in the IntelliJ repository. This is a thin repo-specific overlay: use IntelliJ commit format, write full commit messages by default, and keep requested suffixes such as IJ-MR trailers in a final separate paragraph.

Code style rules for IntelliJ codebase. Use when writing or reviewing code for style compliance.

Guidelines for implementing IntelliJ actions (AnAction). Use those rules when you need to create or change an action in the intellij platform.