mps-aspect-accessories

name	mps-aspect-accessories
description	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.
type	reference

MPS Module and Model Dependencies, Accessory Models

This skill covers the wiring layer of an MPS language — the module descriptor (.mpl) and the per-model imports — and the special role of accessory models and runtime solutions.

Note: accessory wiring does not introduce a new aspect model or stereotype; it edits the existing language descriptor and model imports. When you do need to create a new aspect or stereotyped model, see aspect-model-stereotypes.md for the canonical aspect IDs and @stereotype values.

Critical Directives

• Prefer MCP wiring tools over hand-editing .mpl XML. Hand-editing can silently corrupt the module descriptor. If you must hand-edit (e.g. for accessoryModels, which has no dedicated MCP tool), make a backup, edit only the targeted block, and rebuild the module immediately afterwards so MPS re-reads the descriptor.
• Don't hand-edit languageVersions / dependencyVersions. MPS maintains these. Use the MPS "Update language/dependency versions" action.
• Generator modules have their own dependency list. Add target-language deps to the generator, not the parent language.
• Used languages auto-import when nodes are inserted via mps_mcp_insert_root_node_from_json, mps_mcp_update_node. Manually add a used language only for hand-written code or implicit dependencies.
• A runtime solution holds the stable part of generation (code that doesn't vary with the model). Generate thin code that calls it; don't regenerate it. No MCP tool wires the language's <runtime> block — see references/runtime-solutions.md.

Rule of Thumb — Dependency vs. Used Language

• If a concept is used in your language definition → add a usedLanguage.
• If a Java class is referenced in hand-written code → add a dependency with the right scope.

MCP Tools Quick Reference

• Module-level: mps_mcp_module_dependency, mps_mcp_get_project_structure.
• Model-level: mps_mcp_model_dependency, mps_mcp_model_used_language (kind = language or devkit).
• Module creation: mps_mcp_create_module(type="solution", …) for a runtime solution.

Common Workflow

1. Inspect existing wiring: mps_mcp_get_project_structure(startingPoint=<module>) for the module descriptor, mps_mcp_get_project_structure for traversal.
2. Diagnose the symptom against the pitfalls table (references/pitfalls.md).
3. Apply the right MCP tool at the right layer (module vs. model vs. accessory).
4. Rebuild the module so MPS re-reads the descriptor.

Related Skills

• mps-language-inheritance — when you need the difference between extendedLanguages and usedLanguages in detail.
• mps-aspect-generator — generator-module dependencies are managed separately from the parent language.
• mps-language-aspects-overview — to know which aspects exist and where each one lives.

Reference Index

• Open references/module-level-deps.md for the full list of .mpl declarations (dependencies, usedLanguages, usedDevKits, extendedLanguages, runtimeModules, generators, accessoryModels, version stamps), their scopes, and the mps_mcp_module_dependency scope-dispatch table.
• Open references/model-level-imports.md for per-model dependencies, used languages, used devkits, and the auto-import behavior of node-insertion tools.
• Open references/accessory-models.md when shipping a model that should be available to every consumer of the language without an explicit import — including the .mpl <accessoryModels> XML shape and the hand-edit caveat.
• Open references/runtime-solutions.md for runtime solutions — shipping the Java that generated programs call at run time (the generator's stable part, as MPS source or a prebuilt JAR): the Java-facet settings, the language <runtime>-block wiring, jar-as-stubs (java_classes model root + facet <library>), the no-MCP-tool caveat, and the Kaja/JavaKaja worked example.
• Open references/extends-vs-uses.md for the semantic difference between extendedLanguages and usedLanguages with examples.
• Open references/pitfalls.md when you need to diagnose a symptom ("Cannot resolve concept X", "ClassNotFoundException", version mismatch, generator can't find target-language concept, devkit changes not picked up).
• Open references/module-creation.md for mps_mcp_create_module — supported types, language-only companions (withGenerator/withSandbox/withRuntime), and the facets policy.
• Open references/module-rename.md for mps_mcp_update_module — what the rename cascades into, the "generator modules are not renameable" rule, and the renameWarnings/renameCriticalProblems semantics.
• Open references/module-info-fields.md for the shared info envelope returned by mps_mcp_get_project_structure(startingPoint=<module>) / mps_mcp_create_module / mps_mcp_update_module — kind, facets, loadExtensions, DevKit-only fields.