MPS Generation Plans

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.

A generation plan (Plan) is an ordered script that controls which generators run, in what sequence, and with what synchronization points. Without a plan, MPS determines order from mutual generator priorities and dependencies. A plan lets language designers specify that ordering once, in a single place, without requiring all involved languages to know about each other.

Language: jetbrains.mps.lang.generator.plan (id 7ab1a6fa-0a11-4b95-9e48-75f363d6cb00, version 3) Also requires: jetbrains.mps.lang.smodel (for LanguageId / LanguageIdentity nodes)

When to use a generation plan

• You need a guaranteed ordering of generators across languages that must not depend on each other.
• You are doing cross-model generation and need mapping labels from one model to be available when generating another (requires checkpoints).
• You want to fork the generation of certain models into a separate branch (e.g., generate both .java files and XML descriptors from the same input).
• You want a conditional contribution added to a base plan without modifying it (PlanContribution).

Critical Directives

• Genplan models use the genplan stereotype. File name pattern: <name>@genplan.mps. Pass moduleName: "<hosting module>" and modelName: "<name>@genplan" to mps_mcp_create_model. See aspect-model-stereotypes.md for all model identifiers. Set doNotGenerate=true (MPS adds this automatically).
• Only one DevKit per model may carry a genplan. Assigning multiple genplan-bearing DevKits to the same model is unsupported.
• Plan.steps is 1..n. A plan with no steps is invalid.
• LanguageEntry.language (LanguageId) and GeneratorModulePointer.module (ModulePointer) are each cardinality 1 — missing them is a validation error.
• Checkpoints persist transient state. Cross-phase reference resolution works only when phases share a plan AND a Checkpoint sits between them.
• Do not hand-edit serialized .mps genplan files. Use MPS MCP node tools.

Common-Path Workflow

1. Create a solution; add a model with stereotype genplan (file like MyPlan@genplan.mps).
2. Add used languages jetbrains.mps.lang.generator.plan and jetbrains.mps.lang.smodel.
3. Create a Plan root node with a descriptive name.
4. Add Transform steps in order (one per phase); group parallel-safe languages in one Transform with multiple LanguageEntry children.
5. Insert Checkpoint steps wherever downstream generators must resolve cross-model references.
6. Add Fork steps for any output variant requiring its own branch (e.g. XML alongside Java); or add a separate PlanContribution root for conditional activation.
7. Attach the plan to models via a DevKit (production) or the Custom generation facet (prototyping).
8. Verify with MPS UI Show generation plan and mps_mcp_check_root_node_problems.

Related Skills

• mps-aspect-generator — for the generator rules and templates that the plan orchestrates.
• mps-aspect-textgen — for the text serialization that consumes generated models.
• mps-aspect-accessories — for DevKit setup, used languages, and runtime solutions that ship with a plan.
• mps-node-editing — generic JSON-blueprint node creation workflow.

Reference Index

Start here — most common case: creating a plan and wiring it into a DevKit → read only references/plan-setup.md, plus references/step-catalog.md for the exact step concepts; cross-phase label resolution → only references/checkpoints.md; composing or branching plans → only references/composition-and-fork.md.

• Plan setup and DevKit attachment — open when creating a new genplan model, wiring it into a DevKit, or switching between DevKit and Custom generation facet attachment. See references/plan-setup.md.
• Step concept catalog — open when you need exact concept names, properties, cardinalities, and the meanings of Transform, ApplyGenerators, Checkpoint, IncludePlan, Fork, CheckpointDeclaration, CheckpointSynchronization, DocumentationStep. See references/step-catalog.md.
• Transform and ApplyGenerators — open when wiring languages by identity (LanguageEntry.kind = Transform / TargetAt / Extend) or naming specific generator modules. Includes the verified "the plan" and "WithCompiledGenerator" JSON examples. See references/transform-and-applygenerators.md.
• Checkpoints and cross-model resolution — open when phases need to share mapping labels, when a downstream plan must read another plan's checkpoint, or when picking among InPlaceCheckpointSpec, DeclaredCheckpointSpec, InPlaceCheckpointRefSpec. See references/checkpoints.md.
• IncludePlan, Fork, and PlanContribution — open when composing plans from smaller pieces, splitting branches, or activating a conditional contribution without modifying the base plan. Includes "GenPlanWithFork", "LangConstraintsPlan", and "DocumentationPlan" JSON examples. See references/composition-and-fork.md.
• Fork selectors and parameters — open when conditionally activating forks via ParameterEquals or ConceptListSelector, or defining a ParameterDeclaration. See references/fork-selectors.md.
• Model attributes (InitModelAttributes, targetFacet) — open when routing the output of a branch to a specific facet such as documentation generation. Includes the verified ModelAttributeAssignment blueprint. See references/model-attributes.md.
• Concept quick reference — open when assembling JSON that requires conceptReference strings or qualified concept names. See references/concept-quick-reference.md.
• Verification and discovery — open to find existing plans (FIND_INSTANCES, search by name) or to validate a plan using MPS UI and MCP tools. See references/verification-and-discovery.md.
• Authoring checklist — open at the end of an authoring session for a final scan before merging. See references/authoring-checklist.md.