[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"skill-jetbrains-mps-aspect-typesystem":3,"mdc-qhjmqm-key":32,"related-org-jetbrains-mps-aspect-typesystem":1450,"related-repo-jetbrains-mps-aspect-typesystem":1573},{"slug":4,"name":4,"fn":5,"description":6,"org":7,"tags":11,"stars":19,"repoUrl":20,"updatedAt":21,"license":22,"forks":23,"topics":24,"repo":27,"sourceUrl":30,"mdContent":31},"mps-aspect-typesystem","author MPS typesystem rules","Use when authoring or debugging MPS typesystem — inference rules (`typeof :==: \u002F :\u003C=: \u002F :>=:`), `SubtypingRule`, `ComparisonRule`, `InequationReplacementRule`, `SubstituteTypeRule`, `WhenConcreteStatement` blocks, `NonTypesystemRule` checking rules, `TypesystemQuickFix`, error\u002Fwarning\u002Finfo reports with `messageTarget` highlighting and quick-fix wiring (`helginsIntention`), and shared BaseLanguage helpers in the typesystem model. Reach for this skill whenever the task involves editing `\u003Clang>\u002FlanguageModels\u002Ftypesystem.mps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},"jetbrains","JetBrains","https:\u002F\u002Fpexgzepcugksgbtrxkhf.supabase.co\u002Fstorage\u002Fv1\u002Fobject\u002Fpublic\u002Forg-logos\u002Fjetbrains.png",[12,16],{"name":13,"slug":14,"type":15},"Code Analysis","code-analysis","tag",{"name":17,"slug":18,"type":15},"Debugging","debugging",1650,"https:\u002F\u002Fgithub.com\u002FJetBrains\u002FMPS","2026-07-17T05:29:30.072445",null,311,[25,26],"domain-specific-language","dsl",{"repoUrl":20,"stars":19,"forks":23,"topics":28,"description":29},[25,26],"JetBrains Meta programming System","https:\u002F\u002Fgithub.com\u002FJetBrains\u002FMPS\u002Ftree\u002FHEAD\u002Fplugins\u002Fmcp-tools\u002Fresources\u002Fjetbrains\u002Fmps\u002Fagents\u002Fmcp\u002Fskills\u002Fmps-aspect-typesystem","---\nname: mps-aspect-typesystem\ndescription: >-\n  Use when authoring or debugging MPS typesystem — inference rules (`typeof :==: \u002F :\u003C=: \u002F :>=:`), `SubtypingRule`, `ComparisonRule`, `InequationReplacementRule`, `SubstituteTypeRule`, `WhenConcreteStatement` blocks, `NonTypesystemRule` checking rules, `TypesystemQuickFix`, error\u002Fwarning\u002Finfo reports with `messageTarget` highlighting and quick-fix wiring (`helginsIntention`), and shared BaseLanguage helpers in the typesystem model. Reach for this skill whenever the task involves editing `\u003Clang>\u002FlanguageModels\u002Ftypesystem.mps`.\ntype: reference\n---\n\n# MPS Typesystem and Checking Aspect\n\nThe **typesystem** aspect gives nodes *types* and reports semantic errors. It combines two related sub-aspects:\n\n- **Typesystem rules** — compute types and constraints on them (`InferenceRule`, `SubtypingRule`, `InequationReplacementRule`, `ComparisonRule`, `SubstituteTypeRule`).\n- **Non-typesystem checking rules** — produce errors\u002Fwarnings\u002Fmessages without contributing to type inference (`NonTypesystemRule`, a.k.a. \"checking rule\").\n\nLives in `\u003Clang>\u002FlanguageModels\u002Ftypesystem.mps`, language `jetbrains.mps.lang.typesystem`. Rule bodies are BaseLanguage + smodel + collections + closures.\n\n## Critical Directives\n\n- One `InferenceRule` (or other root rule) per concept whose type\u002Fcheck you compute. Multiple rules collectively constrain a node — keep each rule focused.\n- The `infer` prefix makes an inequation *soft* (the solver tries to satisfy it, will not immediately error). Without `infer`, violating the inequation reports an error. Choose deliberately.\n- In equation\u002Finequation JSON, both `leftExpression` and `rightExpression` are `TypeClause` slots — **always wrap the real Expression in a `NormalTypeClause`** (`normalType` child holds the actual Expression). Do not put the Expression directly under `leftExpression`\u002F`rightExpression`.\n- TextGen-style dispatch caveat does **not** apply here; typesystem rules are inherited via concept hierarchy, but the `overrides` property on a rule suppresses inherited rules from superconcepts.\n- TextGen \u002F typesystem error messages: wrap smodel expressions that render types with `\u003C...>` presentation: `error \"Expected \" + \u003CexpectedType> + \" but got \" + \u003CactualType> -> node;`. Avoid raw `toString`.\n- `when concrete (typeof(expr) as v) { ... }` defers a block until the type is fully resolved — use it before deciding whether to report an error or assign a result type.\n- Quick fixes (`TypesystemQuickFix`) are roots, **not** executed automatically — the user triggers them via the UI. Wire them into a report through the `helginsIntention` slot (`TypesystemIntention` wrapper with `quickFix` ref + `actualArgument`s). See `references\u002Fquick-fixes.md`.\n- Reusable helper code (utility classes, shared algorithms) can live as a plain BaseLanguage `ClassConcept` root **directly in the typesystem model**. No separate utility module is required.\n- For MPS-typed return types (`sequence\u003Cnode\u003CX>>`, `list\u003Cnode\u003CX>>`) the Java parser gives back `List\u003CSNode>` — fix per `mps-model-manipulation\u002Freferences\u002Fvariable-declarations.md`.\n- Edit typesystem models through MPS MCP tools (`mps_mcp_insert_root_node_from_json`, `mps_mcp_update_node`, `mps_mcp_parse_java_and_insert`). Do not hand-edit `.mps` files.\n- After edits run `mps_mcp_check_root_node_problems`, compile the language, and test on sample models.\n\n## Common-Path Workflow\n\n1. Create a `typesystem` model (`mps_mcp_create_model` with `modelName: \"\u003Clang>.typesystem\"` — aspect ID `typesystem`, case-sensitive, no `@` suffix; see [aspect-model-stereotypes.md](..\u002Fmps-mcp-workflow\u002Freferences\u002Faspect-model-stereotypes.md)) if absent.\n2. Add used languages: `jetbrains.mps.lang.typesystem`, and any languages used in bodies (`smodel`, `collections`, `closures`, `baseLanguage`).\n3. Add `InferenceRule` roots for concepts whose types you compute (see `references\u002Finference-rules.md`).\n4. Add `SubtypingRule` \u002F `ComparisonRule` \u002F `InequationReplacementRule` \u002F `SubstituteTypeRule` roots for the type lattice (see `references\u002Flattice-rules.md`).\n5. Add `NonTypesystemRule` roots for checks that are not about types (see `references\u002Fnon-typesystem-checking.md`).\n6. Add `TypesystemQuickFix` roots for any fix you want to attach to reports; wire them via a `helginsIntention`\u002F`TypesystemIntention` child of the `warning`\u002F`error`\u002F`info` statement (see `references\u002Fquick-fixes.md`).\n7. Write bodies with BaseLanguage + smodel. Use `when concrete` (`references\u002Fwhen-concrete.md`) when you need resolved types before checking. For helper code, place a `ClassConcept` root directly in the typesystem model and call it from rules.\n8. Validate: `mps_mcp_check_root_node_problems` plus compile the language and test on sample models. A `helginsIntention`-wired quick fix now surfaces in the check report's `quickFixes` array and can be applied with `mps_mcp_apply_intention(nodeReference = \u003Cproblem node>, intentionId = \u003Cfix id>)`; an auto-applicable fix runs under `autoApplyQuickFixes=true`.\n\n## Related Skills\n\n- `mps-aspect-behavior` — behavior methods called from rule bodies via `node.method()`; common host for `getType` \u002F `isAssignableFrom`-style helpers callable from typesystem.\n- `mps-aspect-constraints` — non-type validation often lives in constraints; consider whether a check belongs there before adding a `NonTypesystemRule`.\n- `mps-aspect-intentions` — distinct from `TypesystemQuickFix` (intentions are user-invoked from caret; quick fixes attach to a report).\n- `mps-model-manipulation` — full BaseLanguage \u002F smodel \u002F collections reference used inside rule bodies (`StatementList`, `DotExpression`, smodel operations, the `List\u003CSNode>` → `sequence\u003Cnode\u003CX>>` return-type fix).\n- `mps-quotations` — `\u003Ctype>` literals in rule bodies are heavy quotations; `%(expr)%` splices use the `Antiquotation` family. The typesystem model usually uses `jetbrains.mps.lang.quotation` as a used language.\n- `mps-aspect-structure-concepts` — when introducing the type concept(s) the rules target.\n\n## Reference Index\n\n- Open `references\u002Finference-rules.md` when writing or debugging an `InferenceRule` — the operator vocabulary (`:==:`, `:\u003C=:`, `:>=:`, soft `infer`, strong `:\u003C\u003C=:` \u002F `:>>=:`), free type variables (`var elementType;`), `join(A | B)`, `%(...)%` anti-quotations in `\u003C...>` literals, and the four worked examples (StringLiteral, ParenthesizedExpression, TernaryOperator, ForEachStatement).\n- Open `references\u002Fwhen-concrete.md` when a rule must wait for a resolved concrete type before deciding — `WhenConcreteStatement` shape, nested `when concrete` blocks, `operation type(op, leftType, rightType)`, and the bound-variable plumbing (`WhenConcreteVariableDeclaration` \u002F `WhenConcreteVariableReference`).\n- Open `references\u002Flattice-rules.md` for the type-lattice rules — `SubtypingRule` (single supertype or `nlist\u003C>` of supertypes), `InequationReplacementRule` (a.k.a. \"replacement rule\", structural subtyping with `isApplicableClause`, `isWeak`, `equationInfo.getNodeWithError()`), `ComparisonRule` (`boolean` body, `weak`), and `SubstituteTypeRule` (`attributedNode`, return-or-null pattern).\n- Open `references\u002Fnon-typesystem-checking.md` when adding a `NonTypesystemRule` (\"checking rule\") — `error \u002F warning \u002F info \"msg\" -> node;`, `isStrongSubtype(typeof(x) :\u003C\u003C t)` for strict-subtype tests, and the `CheckExcessTypeCasts` example.\n- Open `references\u002Fquick-fixes.md` when authoring a `TypesystemQuickFix` and wiring it into a report — `QuickFixArgument` declarations, `executeBlock` \u002F `descriptionBlock`, the three sample fixes (`RemoveExcessTypeCast`, `RemoveMisplacedDash`, `HideCardinalityOne`), and the full JSON for the `helginsIntention` \u002F `TypesystemIntention` \u002F `TypesystemIntentionArgument` plumbing.\n- Open `references\u002Fmessages-and-helpers.md` when crafting messages — the `\u003C...>` type-rendering convention, `messageTarget` to highlight just a property\u002Freference\u002Fchild cell, `PropertyMessageTarget` shape, and shared BaseLanguage helper roots (`ElementSummary` pattern).\n- Open `references\u002Fjson-blueprints.md` when inserting nodes via MCP — body-level skeletons for each equation\u002Finequation kind, `ReportErrorStatement` \u002F `WarningStatement` \u002F `InfoStatement` with optional `helginsIntention` \u002F `messageTarget`, anti-quotation handling inside quotations, minimal rule-root skeletons, and the full validated concept reference with FQNs and concept refs.\n- Open `references\u002Fcommon-failures.md` when a type is `undefined`, subtyping isn't applied, error messages render badly, return types fight the Java parser, rules cycle, quick fixes aren't offered, `when concrete` bodies never run, or `SubstituteTypeRule` seems ignored.\n",{"data":33,"body":35},{"name":4,"description":6,"type":34},"reference",{"type":36,"children":37},"root",[38,47,69,140,161,168,493,499,790,796,962,968],{"type":39,"tag":40,"props":41,"children":43},"element","h1",{"id":42},"mps-typesystem-and-checking-aspect",[44],{"type":45,"value":46},"text","MPS Typesystem and Checking Aspect",{"type":39,"tag":48,"props":49,"children":50},"p",{},[51,53,59,61,67],{"type":45,"value":52},"The ",{"type":39,"tag":54,"props":55,"children":56},"strong",{},[57],{"type":45,"value":58},"typesystem",{"type":45,"value":60}," aspect gives nodes ",{"type":39,"tag":62,"props":63,"children":64},"em",{},[65],{"type":45,"value":66},"types",{"type":45,"value":68}," and reports semantic errors. It combines two related sub-aspects:",{"type":39,"tag":70,"props":71,"children":72},"ul",{},[73,122],{"type":39,"tag":74,"props":75,"children":76},"li",{},[77,82,84,91,93,99,100,106,107,113,114,120],{"type":39,"tag":54,"props":78,"children":79},{},[80],{"type":45,"value":81},"Typesystem rules",{"type":45,"value":83}," — compute types and constraints on them (",{"type":39,"tag":85,"props":86,"children":88},"code",{"className":87},[],[89],{"type":45,"value":90},"InferenceRule",{"type":45,"value":92},", ",{"type":39,"tag":85,"props":94,"children":96},{"className":95},[],[97],{"type":45,"value":98},"SubtypingRule",{"type":45,"value":92},{"type":39,"tag":85,"props":101,"children":103},{"className":102},[],[104],{"type":45,"value":105},"InequationReplacementRule",{"type":45,"value":92},{"type":39,"tag":85,"props":108,"children":110},{"className":109},[],[111],{"type":45,"value":112},"ComparisonRule",{"type":45,"value":92},{"type":39,"tag":85,"props":115,"children":117},{"className":116},[],[118],{"type":45,"value":119},"SubstituteTypeRule",{"type":45,"value":121},").",{"type":39,"tag":74,"props":123,"children":124},{},[125,130,132,138],{"type":39,"tag":54,"props":126,"children":127},{},[128],{"type":45,"value":129},"Non-typesystem checking rules",{"type":45,"value":131}," — produce errors\u002Fwarnings\u002Fmessages without contributing to type inference (",{"type":39,"tag":85,"props":133,"children":135},{"className":134},[],[136],{"type":45,"value":137},"NonTypesystemRule",{"type":45,"value":139},", a.k.a. \"checking rule\").",{"type":39,"tag":48,"props":141,"children":142},{},[143,145,151,153,159],{"type":45,"value":144},"Lives in ",{"type":39,"tag":85,"props":146,"children":148},{"className":147},[],[149],{"type":45,"value":150},"\u003Clang>\u002FlanguageModels\u002Ftypesystem.mps",{"type":45,"value":152},", language ",{"type":39,"tag":85,"props":154,"children":156},{"className":155},[],[157],{"type":45,"value":158},"jetbrains.mps.lang.typesystem",{"type":45,"value":160},". 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Do not put the Expression directly under ",{"type":39,"tag":85,"props":260,"children":262},{"className":261},[],[263],{"type":45,"value":219},{"type":45,"value":265},"\u002F",{"type":39,"tag":85,"props":267,"children":269},{"className":268},[],[270],{"type":45,"value":227},{"type":45,"value":272},".",{"type":39,"tag":74,"props":274,"children":275},{},[276,278,283,285,291],{"type":45,"value":277},"TextGen-style dispatch caveat does ",{"type":39,"tag":54,"props":279,"children":280},{},[281],{"type":45,"value":282},"not",{"type":45,"value":284}," apply here; typesystem rules are inherited via concept hierarchy, but the ",{"type":39,"tag":85,"props":286,"children":288},{"className":287},[],[289],{"type":45,"value":290},"overrides",{"type":45,"value":292}," property on a rule suppresses inherited rules from superconcepts.",{"type":39,"tag":74,"props":294,"children":295},{},[296,298,304,306,312,314,320],{"type":45,"value":297},"TextGen \u002F typesystem error messages: wrap smodel expressions that render types with ",{"type":39,"tag":85,"props":299,"children":301},{"className":300},[],[302],{"type":45,"value":303},"\u003C...>",{"type":45,"value":305}," presentation: ",{"type":39,"tag":85,"props":307,"children":309},{"className":308},[],[310],{"type":45,"value":311},"error \"Expected \" + \u003CexpectedType> + \" but got \" + \u003CactualType> -> node;",{"type":45,"value":313},". 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",{"type":39,"tag":85,"props":1346,"children":1348},{"className":1347},[],[1349],{"type":45,"value":1350},"messageTarget",{"type":45,"value":1352}," to highlight just a property\u002Freference\u002Fchild cell, ",{"type":39,"tag":85,"props":1354,"children":1356},{"className":1355},[],[1357],{"type":45,"value":1358},"PropertyMessageTarget",{"type":45,"value":1360}," shape, and shared BaseLanguage helper roots (",{"type":39,"tag":85,"props":1362,"children":1364},{"className":1363},[],[1365],{"type":45,"value":1366},"ElementSummary",{"type":45,"value":1368}," pattern).",{"type":39,"tag":74,"props":1370,"children":1371},{},[1372,1373,1379,1381,1387,1388,1394,1395,1401,1403,1408,1409,1414],{"type":45,"value":975},{"type":39,"tag":85,"props":1374,"children":1376},{"className":1375},[],[1377],{"type":45,"value":1378},"references\u002Fjson-blueprints.md",{"type":45,"value":1380}," when inserting nodes via MCP — body-level skeletons for each equation\u002Finequation kind, ",{"type":39,"tag":85,"props":1382,"children":1384},{"className":1383},[],[1385],{"type":45,"value":1386},"ReportErrorStatement",{"type":45,"value":624},{"type":39,"tag":85,"props":1389,"children":1391},{"className":1390},[],[1392],{"type":45,"value":1393},"WarningStatement",{"type":45,"value":624},{"type":39,"tag":85,"props":1396,"children":1398},{"className":1397},[],[1399],{"type":45,"value":1400},"InfoStatement",{"type":45,"value":1402}," with optional ",{"type":39,"tag":85,"props":1404,"children":1406},{"className":1405},[],[1407],{"type":45,"value":356},{"type":45,"value":624},{"type":39,"tag":85,"props":1410,"children":1412},{"className":1411},[],[1413],{"type":45,"value":1350},{"type":45,"value":1415},", anti-quotation handling inside quotations, minimal rule-root skeletons, and the full validated concept reference with FQNs and concept refs.",{"type":39,"tag":74,"props":1417,"children":1418},{},[1419,1420,1426,1428,1434,1436,1441,1443,1448],{"type":45,"value":975},{"type":39,"tag":85,"props":1421,"children":1423},{"className":1422},[],[1424],{"type":45,"value":1425},"references\u002Fcommon-failures.md",{"type":45,"value":1427}," when a type is ",{"type":39,"tag":85,"props":1429,"children":1431},{"className":1430},[],[1432],{"type":45,"value":1433},"undefined",{"type":45,"value":1435},", subtyping isn't applied, error messages render badly, return types fight the Java parser, rules cycle, quick fixes aren't offered, ",{"type":39,"tag":85,"props":1437,"children":1439},{"className":1438},[],[1440],{"type":45,"value":731},{"type":45,"value":1442}," bodies never run, or ",{"type":39,"tag":85,"props":1444,"children":1446},{"className":1445},[],[1447],{"type":45,"value":119},{"type":45,"value":1449}," seems ignored.",{"items":1451,"total":1572},[1452,1468,1477,1485,1493,1503,1516,1525,1534,1544,1552,1563],{"slug":1453,"name":1453,"fn":1454,"description":1455,"org":1456,"tags":1457,"stars":19,"repoUrl":20,"updatedAt":1467},"mps-aspect-accessories","configure JetBrains MPS module dependencies","Wire MPS module and model dependencies, used languages, used devkits, extended languages, runtime solutions, accessory models, and language\u002Fdependency versions. Use when adding\u002Fremoving module dependencies, importing languages or devkits into a model, declaring runtime solutions, or shipping accessory content visible to consumers without explicit import.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1458,1461,1464],{"name":1459,"slug":1460,"type":15},"Architecture","architecture",{"name":1462,"slug":1463,"type":15},"Configuration","configuration",{"name":1465,"slug":1466,"type":15},"Engineering","engineering","2026-07-17T06:06:57.311661",{"slug":1469,"name":1469,"fn":1470,"description":1471,"org":1472,"tags":1473,"stars":19,"repoUrl":20,"updatedAt":1476},"mps-aspect-actions","define and edit MPS node factories","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.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1474,1475],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},"2026-07-17T06:04:48.066901",{"slug":807,"name":807,"fn":1478,"description":1479,"org":1480,"tags":1481,"stars":19,"repoUrl":20,"updatedAt":1484},"define and edit MPS concept behavior","Use when defining or editing MPS `ConceptBehavior` — per-concept methods (non-virtual \u002F virtual \u002F abstract \u002F static \u002F virtual static), constructors, virtual dispatch (MRO), super and interface-default calls (`super\u003CInterface>.method`), overriding methods from `lang.core.behavior` interfaces such as `ScopeProvider.getScope` \u002F `INamedConcept.getName` \u002F `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 `\u003Clang>\u002FlanguageModels\u002Fbehavior.mps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1482,1483],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},"2026-07-13T06:45:21.757084",{"slug":841,"name":841,"fn":1486,"description":1487,"org":1488,"tags":1489,"stars":19,"repoUrl":20,"updatedAt":1492},"define JetBrains MPS language constraints","Use when defining or editing MPS language constraints — property validators \u002F setters \u002F getters, referent search scopes (imperative or inherited via `ScopeProvider.getScope`), `referentSetHandler` side effects, default-scope blocks, `canBeChild` \u002F `canBeParent` \u002F `canBeAncestor` \u002F `canBeRoot` placement rules, `defaultConcreteConcept` for abstract concepts, `set \u003Cread-only>` and `{name}` aliasing, and scope helpers (`SimpleRoleScope`, `ListScope`, `CompositeScope`, `HidingByNameScope`). Reach for this skill whenever the task involves authoring or modifying `\u003Clang>\u002FlanguageModels\u002Fconstraints.mps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1490,1491],{"name":1459,"slug":1460,"type":15},{"name":13,"slug":14,"type":15},"2026-07-23T05:41:33.639365",{"slug":1494,"name":1494,"fn":1495,"description":1496,"org":1497,"tags":1498,"stars":19,"repoUrl":20,"updatedAt":1502},"mps-aspect-dataflow","define and debug MPS dataflow builders","Use when defining or debugging MPS dataflow builders for a concept — control\u002Fdata 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\u002Fnon-null tracking.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1499],{"name":1500,"slug":1501,"type":15},"Data Analysis","data-analysis","2026-07-13T06:45:19.114674",{"slug":1504,"name":1504,"fn":1505,"description":1506,"org":1507,"tags":1508,"stars":19,"repoUrl":20,"updatedAt":1515},"mps-aspect-editor","define MPS editor layouts","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`\u002F`CellModel_RefNodeList`\u002F`CellModel_RefCell`\u002F`CellModel_Property`\u002F`CellModel_Constant`), layout choices, and JSON blueprints for common editor shapes. For the non-layout side (action maps, keymaps, transformation\u002Fsubstitute menus) use `mps-aspect-editor-menus-and-keymaps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1509,1512],{"name":1510,"slug":1511,"type":15},"Design","design",{"name":1513,"slug":1514,"type":15},"UI Components","ui-components","2026-07-23T05:41:56.638151",{"slug":1517,"name":1517,"fn":1518,"description":1519,"org":1520,"tags":1521,"stars":19,"repoUrl":20,"updatedAt":1524},"mps-aspect-editor-menus-and-keymaps","author MPS 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` \u002F `_Named` \u002F `_Contribution`), substitute menus (`SubstituteMenu_Default` \u002F `SubstituteMenu` \u002F contributions), side transforms (LEFT\u002FRIGHT), 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.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1522,1523],{"name":1465,"slug":1466,"type":15},{"name":1513,"slug":1514,"type":15},"2026-07-23T05:41:49.666535",{"slug":1526,"name":1526,"fn":1527,"description":1528,"org":1529,"tags":1530,"stars":19,"repoUrl":20,"updatedAt":1533},"mps-aspect-generation-plan","modify MPS generation plans","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\u002FConceptListSelector 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.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1531,1532],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},"2026-07-13T06:44:59.507855",{"slug":1535,"name":1535,"fn":1536,"description":1537,"org":1538,"tags":1539,"stars":19,"repoUrl":20,"updatedAt":1543},"mps-aspect-generator","define JetBrains MPS generator rules","Use when defining or modifying MPS generators — author a generator module, add or edit root\u002Freduction\u002Fweaving\u002Fpattern 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\u002Fpost mapping scripts, navigate `genContext`, or debug \"rule didn't fire\", missing references, empty output, infinite reduction loops, and generated-Java compile failures.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1540,1541,1542],{"name":1459,"slug":1460,"type":15},{"name":13,"slug":14,"type":15},{"name":1465,"slug":1466,"type":15},"2026-07-17T06:06:58.042999",{"slug":858,"name":858,"fn":1545,"description":1546,"org":1547,"tags":1548,"stars":19,"repoUrl":20,"updatedAt":1551},"define and edit MPS intentions","Use when defining or editing MPS intentions (the Alt+Enter context-action aspect) — adding `IntentionDeclaration` roots, parameterized or surround-with variants, description\u002FisApplicable\u002Fexecute 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`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1549,1550],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},"2026-07-23T05:41:48.692899",{"slug":1553,"name":1553,"fn":1554,"description":1555,"org":1556,"tags":1557,"stars":19,"repoUrl":20,"updatedAt":1562},"mps-aspect-migrations","author and debug MPS migration scripts","Use when authoring or debugging MPS migration scripts that upgrade user models after a language definition changes — covers jetbrains.mps.lang.migration (MigrationScript class-based, PureMigrationScript declarative, MoveConcept\u002FMoveContainmentLink\u002FMoveReferenceLink\u002FMoveProperty, ordering via OrderDependency, data exchange via putData\u002FgetData, RefactoringLog, ConceptMigrationReference) and jetbrains.mps.lang.script Enhancement Scripts (MigrationScript with MigrationScriptPart_Instance, ExtractInterfaceMigration, FactoryMigrationScriptPart, CommentMigrationScriptPart) — when a model needs version-gated upgrade, concept rename or removal, link or property rename, instance-level transformation, or composition of migration steps.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1558,1559],{"name":17,"slug":18,"type":15},{"name":1560,"slug":1561,"type":15},"Migration","migration","2026-07-13T06:45:20.372122",{"slug":959,"name":959,"fn":1564,"description":1565,"org":1566,"tags":1567,"stars":19,"repoUrl":20,"updatedAt":1571},"define concepts in MPS structure aspect","Define concepts, interface concepts, enumerations, and constrained data types in an MPS language's `structure` aspect. Covers smart-reference detection, alias rules, cardinality, INamedConcept usage, bulk creation, and the full `mps_mcp_alter_structure` \u002F `mps_mcp_query_structure` reference. Use when authoring or modifying a language's structure model.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1568],{"name":1569,"slug":1570,"type":15},"Data Modeling","data-modeling","2026-07-23T05:41:30.705975",188,{"items":1574,"total":1610},[1575,1581,1586,1591,1596,1600,1605],{"slug":1453,"name":1453,"fn":1454,"description":1455,"org":1576,"tags":1577,"stars":19,"repoUrl":20,"updatedAt":1467},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1578,1579,1580],{"name":1459,"slug":1460,"type":15},{"name":1462,"slug":1463,"type":15},{"name":1465,"slug":1466,"type":15},{"slug":1469,"name":1469,"fn":1470,"description":1471,"org":1582,"tags":1583,"stars":19,"repoUrl":20,"updatedAt":1476},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1584,1585],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},{"slug":807,"name":807,"fn":1478,"description":1479,"org":1587,"tags":1588,"stars":19,"repoUrl":20,"updatedAt":1484},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1589,1590],{"name":1459,"slug":1460,"type":15},{"name":1465,"slug":1466,"type":15},{"slug":841,"name":841,"fn":1486,"description":1487,"org":1592,"tags":1593,"stars":19,"repoUrl":20,"updatedAt":1492},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1594,1595],{"name":1459,"slug":1460,"type":15},{"name":13,"slug":14,"type":15},{"slug":1494,"name":1494,"fn":1495,"description":1496,"org":1597,"tags":1598,"stars":19,"repoUrl":20,"updatedAt":1502},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1599],{"name":1500,"slug":1501,"type":15},{"slug":1504,"name":1504,"fn":1505,"description":1506,"org":1601,"tags":1602,"stars":19,"repoUrl":20,"updatedAt":1515},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1603,1604],{"name":1510,"slug":1511,"type":15},{"name":1513,"slug":1514,"type":15},{"slug":1517,"name":1517,"fn":1518,"description":1519,"org":1606,"tags":1607,"stars":19,"repoUrl":20,"updatedAt":1524},{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[1608,1609],{"name":1465,"slug":1466,"type":15},{"name":1513,"slug":1514,"type":15},31]