MPS: Skill for Claude Code

Writing MPS BaseLanguage with smodel

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.

Use this skill when authoring code inside an MPS model where BaseLanguage is mixed with the smodel extension: 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 / #usages / #nodes / #references / #models / #modules and a with (<scope>) { … } wrapper, the same queries the MPS Console runs. Its results compose with the smodel operations catalogued here and the collection operations of mps-collections-and-closures. See the mps-console skill.

Minimum reading set

references/ is a lookup catalog, not a syllabus. One file is enough to write the body. The common failure here is the opposite: five catalogs (~60 KB) read to author one behavior method and one checking rule.