# Mps Aspect Generation Plan > 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/ConceptListSelector 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. - Skill: `jetbrains/mps-aspect-generation-plan` (Agent Skill, multi-file: 11 files) - Install (CLI): `npx skillmds@latest add jetbrains/mps-aspect-generation-plan` - Raw SKILL.md: https://api.skillmd.com/api/skills/jetbrains/mps-aspect-generation-plan/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: jetbrains (https://skillmd.com/u/jetbrains) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/jetbrains/mps-aspect-generation-plan --- # MPS Generation Plans 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: `@genplan.mps`. Pass `modelName: "@genplan"` to `mps_mcp_create_model`. See [aspect-model-stereotypes.md](../mps-mcp-workflow/references/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 - 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](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](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](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](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](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](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](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](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](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](references/authoring-checklist.md).