mps-model-manipulation

name	mps-model-manipulation
description	Use when writing or editing MPS BaseLanguage code that lives inside a model — behavior methods, typesystem rules, checking rules, generator queries, constraints, intentions, scope/canBe callbacks, dataflow builders — and combines the `smodel`, `collections`, and `closures` language extensions. Covers querying nodes (`.descendants<C>`, `.ancestor<C>`, `.children`, `.parent`, `containingRoot`), filtering sequences (`.where`, `.select`, `.translate`, `.ofConcept<C>`), building closures (`{ it => ... }`, `yield`, recursion), creating and mutating nodes (`new node<C>()`, `add new(C)`, `set new(C)`, `replace with new(C)`, `.detach`, `.copy`), property and link access (`SPropertyAccess`, `SLinkAccess`, `SLinkListAccess`), reference operations (`.reference/C : role/`, `.target`), null-safe node equality (`:eq:` / `:ne:`), smodel/Java type casts (`node:C`, `node as C`, `/`, `downcast`), foreach choice, the `command` / `read action` lock wrappers, and JSON blueprints for every shape the Java parser cannot produce.
type	reference

Writing MPS BaseLanguage with smodel / collections / closures

Use this skill when authoring code inside an MPS model where BaseLanguage is mixed with the smodel, collections, and closures extensions: behavior methods, checking/typesystem/dataflow rules, generator query functions, intentions, constraints, scope/canBe callbacks. The mps_mcp_parse_java_and_insert parser understands only plain Java, so most non-trivial code requires hand-built node blueprints — this skill is the catalog.

To enumerate nodes/instances/usages across a scope (a whole project, module, model, or repository) rather than navigating from one root, add the jetbrains.mps.lang.smodel.query language — it supplies #instances / / / / / and a wrapper, the same queries the MPS Console runs. Its results compose with the // operations catalogued here. See the skill.