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Use when defining error payloads, mapping framework and domain exceptions, standardizing HTTP status codes, adding `@ControllerAdvice`, preventing internal-detail leakage, or ensuring clients can rely on stable machine-readable error semantics across endpoints.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},"jetbrains","JetBrains","https:\u002F\u002Fpexgzepcugksgbtrxkhf.supabase.co\u002Fstorage\u002Fv1\u002Fobject\u002Fpublic\u002Forg-logos\u002Fjetbrains.png",[12,16,19,22],{"name":13,"slug":14,"type":15},"Kotlin","kotlin","tag",{"name":17,"slug":18,"type":15},"Validation","validation",{"name":20,"slug":21,"type":15},"Spring","spring",{"name":23,"slug":24,"type":15},"API Development","api-development",252,"https:\u002F\u002Fgithub.com\u002FJetBrains\u002Fskills","2026-07-13T06:41:17.388577",null,17,[],{"repoUrl":26,"stars":25,"forks":29,"topics":32,"description":33},[],"Curated agent skills collection verified by JetBrains","https:\u002F\u002Fgithub.com\u002FJetBrains\u002Fskills\u002Ftree\u002FHEAD\u002Ferror-model-validation-architect","---\nname: error-model-validation-architect\ndescription: Design and implement consistent API validation and error-handling behavior for Kotlin plus Spring services. Use when defining error payloads, mapping framework and domain exceptions, standardizing HTTP status codes, adding `@ControllerAdvice`, preventing internal-detail leakage, or ensuring clients can rely on stable machine-readable error semantics across endpoints.\nmetadata:\n  short-description: \"Design safe and consistent API errors\"\n  author: Kotlin\n  source: https:\u002F\u002Fgithub.com\u002FKotlin\u002Fkotlin-backend-agent-skills\u002Ftree\u002Fmain\u002F.agents\u002Fskills\u002Ferror-model-validation-architect\n---\n\n# Error Model Validation Architect\n\nSource mapping: Tier 2 high-value skill derived from `Kotlin_Spring_Developer_Pipeline.md` (`SK-07`).\n\n## Mission\n\nTurn ad-hoc exception handling into a deliberate public contract.\nTreat validation and error mapping as part of API design, not a post-processing afterthought.\n\n## Inputs To Read\n\n- Endpoint contracts and sample payloads.\n- Existing exception classes and error payloads.\n- Validation annotations, custom validators, and business rule failures.\n- Current `@ControllerAdvice`, security exception handling, and framework defaults.\n- Logging and observability conventions, especially correlation ids and PII policy.\n\n## Design The Error Taxonomy\n\nSeparate at least these categories:\n\n- malformed request or unreadable JSON\n- transport-level validation failure\n- not found\n- conflict or concurrency failure\n- business rule rejection\n- authentication and authorization failure\n- downstream dependency failure\n- unexpected internal failure\n\nDo not collapse all non-success outcomes into one generic error envelope.\n\n## Status Code Rules\n\n- Use `400` for malformed input, type mismatch, or invalid transport shape.\n- Use `401` for authentication failure and `403` for authorization failure.\n- Use `404` when the addressed resource is absent.\n- Use `409` for state conflicts, optimistic locking failures, duplicate idempotency keys, and uniqueness races when conflict semantics matter.\n- Use `422` when the payload is structurally valid but violates business rules.\n- Use `429`, `502`, `503`, or `504` deliberately when gateway or dependency behavior is part of the contract.\n- Reserve `500` for genuinely unexpected internal failures.\n\n## Advanced Contract Decisions\n\n- Separate machine-readable error code from human-readable message. Clients should not parse prose.\n- Decide whether field-level validation errors should be aggregated or first-failure only. Make the rule consistent.\n- Preserve nested field paths for complex payloads and collections.\n- Decide whether localization is a server concern, client concern, or documentation-only concern.\n- Standardize correlation or trace identifiers in the error payload only if the platform can produce them consistently.\n- Decide how unknown fields, enum mismatches, and unreadable date formats surface. These are common client-integration pain points.\n- Map downstream failures carefully. Not every remote `500` should become your own `500`.\n- If using RFC 7807 Problem Details, decide which extensions are stable parts of the contract and which are internal.\n\n## Validation Rules\n\n- Keep transport validation separate from domain validation even if both ultimately reject the request.\n- Use Kotlin `@field:` targets for Bean Validation annotations on DTO constructor properties.\n- Prefer dedicated validators or domain rules over abusing regex annotations for business semantics.\n- Validate required configuration or invariants at startup when they are not truly request-scoped.\n\n## Framework Exception Coverage\n\n- Cover `MethodArgumentNotValidException`, `ConstraintViolationException`, `HttpMessageNotReadableException`, `MethodArgumentTypeMismatchException`, missing-parameter exceptions, and unsupported media-type cases explicitly if the API claims a stable error contract.\n- Decide how security exceptions participate in the shared error model. `AuthenticationEntryPoint` and `AccessDeniedHandler` often need explicit alignment with controller advice.\n- Decide how async, scheduled, and messaging failures are reported differently from HTTP failures. One global envelope does not fit every boundary.\n- If the platform uses Problem Details, verify framework-generated problem payloads do not diverge from custom ones during upgrades.\n\n## Expert Heuristics\n\n- Let validation errors help the client recover, but let internal logs help operators diagnose. These are different audiences and should not share the same detail level.\n- If the service is public, keep error-code taxonomy versionable and stable even when internal exception types change.\n- When multiple validation layers reject the same request, choose the most user-actionable signal instead of stacking redundant errors.\n- If a downstream dependency failure is part of the business path, decide whether the contract should expose dependency semantics or normalize them to your own domain.\n\n## Output Contract\n\nReturn these sections:\n\n- `Error taxonomy`: the categories and stable codes.\n- `Status mapping`: which exception or failure type maps to which status and why.\n- `Payload shape`: the fields that belong in every error.\n- `Framework coverage`: which framework exceptions must be handled explicitly.\n- `Minimal implementation plan`: advice class, exception types, and tests to add.\n- `Logging rule`: what to log server-side versus what to expose to clients.\n\n## 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Use when adding\u002Fremoving module dependencies, importing languages or devkits into a model, declaring runtime solutions, or shipping accessory content visible to consumers without explicit import.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[658,661,664],{"name":659,"slug":660,"type":15},"Architecture","architecture",{"name":662,"slug":663,"type":15},"Configuration","configuration",{"name":665,"slug":666,"type":15},"Engineering","engineering",1650,"https:\u002F\u002Fgithub.com\u002FJetBrains\u002FMPS","2026-07-17T06:06:57.311661",{"slug":671,"name":671,"fn":672,"description":673,"org":674,"tags":675,"stars":667,"repoUrl":668,"updatedAt":678},"mps-aspect-actions","define and edit MPS node factories","Use when defining or editing MPS node factories (the \"actions\" aspect) — `NodeFactories` roots, per-concept `NodeFactory` setup functions that initialize a freshly created node and optionally copy data from a replaced `sampleNode`, plus the actions aspect's `CopyPasteHandlers` and `PasteWrappers` roots. Reach for this skill when a substitution, side transform, completion replacement, or `add new initialized(...)` should preserve fields from the node it is replacing, or when defaults set in a constructor are not enough.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[676,677],{"name":659,"slug":660,"type":15},{"name":665,"slug":666,"type":15},"2026-07-17T06:04:48.066901",{"slug":680,"name":680,"fn":681,"description":682,"org":683,"tags":684,"stars":667,"repoUrl":668,"updatedAt":687},"mps-aspect-behavior","define and edit MPS concept behavior","Use when defining or editing MPS `ConceptBehavior` — per-concept methods (non-virtual \u002F virtual \u002F abstract \u002F static \u002F virtual static), constructors, virtual dispatch (MRO), super and interface-default calls (`super\u003CInterface>.method`), overriding methods from `lang.core.behavior` interfaces such as `ScopeProvider.getScope` \u002F `INamedConcept.getName` \u002F `BaseConcept.getPresentation`, calling sibling methods (`LocalBehaviorMethodCall`) and behavior methods from other aspects via `node.method(...)`. Reach for this skill whenever the task involves authoring or modifying `\u003Clang>\u002FlanguageModels\u002Fbehavior.mps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[685,686],{"name":659,"slug":660,"type":15},{"name":665,"slug":666,"type":15},"2026-07-13T06:45:21.757084",{"slug":689,"name":689,"fn":690,"description":691,"org":692,"tags":693,"stars":667,"repoUrl":668,"updatedAt":698},"mps-aspect-constraints","define JetBrains MPS language constraints","Use when defining or editing MPS language constraints — property validators \u002F setters \u002F getters, referent search scopes (imperative or inherited via `ScopeProvider.getScope`), `referentSetHandler` side effects, default-scope blocks, `canBeChild` \u002F `canBeParent` \u002F `canBeAncestor` \u002F `canBeRoot` placement rules, `defaultConcreteConcept` for abstract concepts, `set \u003Cread-only>` and `{name}` aliasing, and scope helpers (`SimpleRoleScope`, `ListScope`, `CompositeScope`, `HidingByNameScope`). Reach for this skill whenever the task involves authoring or modifying `\u003Clang>\u002FlanguageModels\u002Fconstraints.mps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[694,695],{"name":659,"slug":660,"type":15},{"name":696,"slug":697,"type":15},"Code Analysis","code-analysis","2026-07-23T05:41:33.639365",{"slug":700,"name":700,"fn":701,"description":702,"org":703,"tags":704,"stars":667,"repoUrl":668,"updatedAt":708},"mps-aspect-dataflow","define and debug MPS dataflow builders","Use when defining or debugging MPS dataflow builders for a concept — control\u002Fdata flow declarations that drive reachability analysis and variable-use checking. Covers DataFlowBuilderDeclaration, BuilderBlock, emit instructions (code for, jump, ifjump, label, read, write, ret, mayBeUnreachable), positions (AfterPosition, BeforePosition, LabelPosition), the jetbrains.mps.lang.dataFlow language, the NodeParameter implicit, BL+smodel usage inside builder bodies, and IBuilderMode for advanced analyses such as nullable\u002Fnon-null tracking.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[705],{"name":706,"slug":707,"type":15},"Data Analysis","data-analysis","2026-07-13T06:45:19.114674",{"slug":710,"name":710,"fn":711,"description":712,"org":713,"tags":714,"stars":667,"repoUrl":668,"updatedAt":721},"mps-aspect-editor","define MPS editor layouts","Use when creating or changing MPS editor definitions — the overall workflow from scaffolding a `ConceptEditorDeclaration` through componentizing reusable `EditorComponentDeclaration`s, refining cell models and cell layouts, applying style sheets and indent-layout style items, wiring smart references, leveraging inheritance via super-concepts and interfaces, inspecting (`print_node_json`, `show_node_representation`) and validating (`check_root_node_problems`). Covers `jetbrains.mps.lang.editor` cell models (`CellModel_RefNode`\u002F`CellModel_RefNodeList`\u002F`CellModel_RefCell`\u002F`CellModel_Property`\u002F`CellModel_Constant`), layout choices, and JSON blueprints for common editor shapes. For the non-layout side (action maps, keymaps, transformation\u002Fsubstitute menus) use `mps-aspect-editor-menus-and-keymaps`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[715,718],{"name":716,"slug":717,"type":15},"Design","design",{"name":719,"slug":720,"type":15},"UI Components","ui-components","2026-07-23T05:41:56.638151",{"slug":723,"name":723,"fn":724,"description":725,"org":726,"tags":727,"stars":667,"repoUrl":668,"updatedAt":730},"mps-aspect-editor-menus-and-keymaps","author MPS editor menus and keymaps","Use when authoring the **non-layout** parts of the MPS editor aspect — what happens when the user types, presses a key, triggers completion, pastes, or invokes a context action. Covers action maps (`CellActionMapDeclaration`), cell keymaps (`CellKeyMapDeclaration`), transformation menus (`TransformationMenu_Default` \u002F `_Named` \u002F `_Contribution`), substitute menus (`SubstituteMenu_Default` \u002F `SubstituteMenu` \u002F contributions), side transforms (LEFT\u002FRIGHT), legacy cell menus, paste wrappers and copy-paste handlers (in the actions language), completion styling, reference presentation, two-step deletion, and the editor selection API. Trigger terms: `actionMap`, `keyMap`, `delete_action_id`, `transformationMenu`, `substituteMenu`, `Ctrl+Space`, `Ctrl+Alt+B`, side transform, paste wrapper, completion styling, `PasteWrappers`, `CopyPasteHandlers`. For the **layout** side (cells, layouts, style sheets) use `mps-aspect-editor` instead.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[728,729],{"name":665,"slug":666,"type":15},{"name":719,"slug":720,"type":15},"2026-07-23T05:41:49.666535",{"slug":732,"name":732,"fn":733,"description":734,"org":735,"tags":736,"stars":667,"repoUrl":668,"updatedAt":739},"mps-aspect-generation-plan","modify MPS generation plans","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\u002FConceptListSelector 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.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[737,738],{"name":659,"slug":660,"type":15},{"name":665,"slug":666,"type":15},"2026-07-13T06:44:59.507855",{"slug":741,"name":741,"fn":742,"description":743,"org":744,"tags":745,"stars":667,"repoUrl":668,"updatedAt":749},"mps-aspect-generator","define JetBrains MPS generator rules","Use when defining or modifying MPS generators — author a generator module, add or edit root\u002Freduction\u002Fweaving\u002Fpattern mapping rules, attach template macros ($COPY_SRC, $LOOP, $IF, $PROPERTY, $REF, $SWITCH, $MAP_SRC, $WEAVE, $INSERT, $LABEL, $TRACE, $VAR), wire mapping labels, build template switches, write pre\u002Fpost mapping scripts, navigate `genContext`, or debug \"rule didn't fire\", missing references, empty output, infinite reduction loops, and generated-Java compile failures.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[746,747,748],{"name":659,"slug":660,"type":15},{"name":696,"slug":697,"type":15},{"name":665,"slug":666,"type":15},"2026-07-17T06:06:58.042999",{"slug":751,"name":751,"fn":752,"description":753,"org":754,"tags":755,"stars":667,"repoUrl":668,"updatedAt":758},"mps-aspect-intentions","define and edit MPS intentions","Use when defining or editing MPS intentions (the Alt+Enter context-action aspect) — adding `IntentionDeclaration` roots, parameterized or surround-with variants, description\u002FisApplicable\u002Fexecute blocks, child-filter functions, factory-initialized AST splicing, or debugging why an intention is not offered. Lives in the language's `intentions` model and uses `jetbrains.mps.lang.intentions`.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[756,757],{"name":659,"slug":660,"type":15},{"name":665,"slug":666,"type":15},"2026-07-23T05:41:48.692899",{"slug":760,"name":760,"fn":761,"description":762,"org":763,"tags":764,"stars":667,"repoUrl":668,"updatedAt":771},"mps-aspect-migrations","author and debug MPS migration scripts","Use when authoring or debugging MPS migration scripts that upgrade user models after a language definition changes — covers jetbrains.mps.lang.migration (MigrationScript class-based, PureMigrationScript declarative, MoveConcept\u002FMoveContainmentLink\u002FMoveReferenceLink\u002FMoveProperty, ordering via OrderDependency, data exchange via putData\u002FgetData, RefactoringLog, ConceptMigrationReference) and jetbrains.mps.lang.script Enhancement Scripts (MigrationScript with MigrationScriptPart_Instance, ExtractInterfaceMigration, FactoryMigrationScriptPart, CommentMigrationScriptPart) — when a model needs version-gated upgrade, concept rename or removal, link or property rename, instance-level transformation, or composition of migration steps.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[765,768],{"name":766,"slug":767,"type":15},"Debugging","debugging",{"name":769,"slug":770,"type":15},"Migration","migration","2026-07-13T06:45:20.372122",{"slug":773,"name":773,"fn":774,"description":775,"org":776,"tags":777,"stars":667,"repoUrl":668,"updatedAt":781},"mps-aspect-structure-concepts","define concepts in MPS structure aspect","Define concepts, interface concepts, enumerations, and constrained data types in an MPS language's `structure` aspect. Covers smart-reference detection, alias rules, cardinality, INamedConcept usage, bulk creation, and the full `mps_mcp_alter_structure` \u002F `mps_mcp_query_structure` reference. Use when authoring or modifying a language's structure model.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[778],{"name":779,"slug":780,"type":15},"Data Modeling","data-modeling","2026-07-23T05:41:30.705975",188,{"items":784,"total":898},[785,804,819,833,848,867,884],{"slug":786,"name":786,"fn":787,"description":788,"org":789,"tags":790,"stars":25,"repoUrl":26,"updatedAt":803},"algorithmic-art","create generative art with p5.js","Creating algorithmic art using p5.js with seeded randomness and interactive parameter exploration. Use this when users request creating art using code, generative art, algorithmic art, flow fields, or particle systems. Create original algorithmic art rather than copying existing artists' work to avoid copyright violations.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[791,794,797,800],{"name":792,"slug":793,"type":15},"Creative","creative",{"name":795,"slug":796,"type":15},"Generative Art","generative-art",{"name":798,"slug":799,"type":15},"Graphics","graphics",{"name":801,"slug":802,"type":15},"JavaScript","javascript","2026-07-13T06:41:35.540127",{"slug":805,"name":805,"fn":806,"description":807,"org":808,"tags":809,"stars":25,"repoUrl":26,"updatedAt":818},"antfu","configure JavaScript projects with Anthony Fu's tools","Anthony Fu's opinionated tooling and conventions for JavaScript\u002FTypeScript projects. Use when setting up new projects, configuring ESLint\u002FPrettier alternatives, monorepos, library publishing, or when the user mentions Anthony Fu's preferences.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[810,813,814,815],{"name":811,"slug":812,"type":15},"Best Practices","best-practices",{"name":665,"slug":666,"type":15},{"name":801,"slug":802,"type":15},{"name":816,"slug":817,"type":15},"TypeScript","typescript","2026-07-13T06:43:13.153309",{"slug":820,"name":820,"fn":821,"description":822,"org":823,"tags":824,"stars":25,"repoUrl":26,"updatedAt":832},"brand-guidelines","apply Anthropic brand guidelines","Applies Anthropic's official brand colors and typography to any sort of artifact that may benefit from having Anthropic's look-and-feel. Use it when brand colors or style guidelines, visual formatting, or company design standards apply.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[825,828,829],{"name":826,"slug":827,"type":15},"Branding","branding",{"name":716,"slug":717,"type":15},{"name":830,"slug":831,"type":15},"Typography","typography","2026-07-13T06:43:06.077629",{"slug":834,"name":834,"fn":835,"description":836,"org":837,"tags":838,"stars":25,"repoUrl":26,"updatedAt":847},"canvas-design","create visual art and design assets","Create beautiful visual art in .png and .pdf documents using design philosophy. You should use this skill when the user asks to create a poster, piece of art, design, or other static piece. Create original visual designs, never copying existing artists' work to avoid copyright violations.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[839,840,841,844],{"name":792,"slug":793,"type":15},{"name":716,"slug":717,"type":15},{"name":842,"slug":843,"type":15},"Images","images",{"name":845,"slug":846,"type":15},"PDF","pdf","2026-07-13T06:39:58.803113",{"slug":849,"name":849,"fn":850,"description":851,"org":852,"tags":853,"stars":25,"repoUrl":26,"updatedAt":866},"ci-cd-containerization-advisor","design CI\u002FCD pipelines for Kotlin applications","Design reproducible build, image, and deployment pipelines for Kotlin plus Spring applications, including CI verification, layered containers, rollout safety, and deployment-time migration coordination. Use when creating or improving Dockerfiles, CI workflows, image hardening, Kubernetes manifests, release gates, or deployment strategies for Spring Boot services, especially where build reproducibility and operational safety matter.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[854,857,860,863,864,865],{"name":855,"slug":856,"type":15},"CI\u002FCD","ci-cd",{"name":858,"slug":859,"type":15},"Containers","containers",{"name":861,"slug":862,"type":15},"Deployment","deployment",{"name":665,"slug":666,"type":15},{"name":13,"slug":14,"type":15},{"name":20,"slug":21,"type":15},"2026-07-13T06:41:47.83899",{"slug":868,"name":868,"fn":869,"description":870,"org":871,"tags":872,"stars":25,"repoUrl":26,"updatedAt":883},"cloudflare-deploy","deploy applications to Cloudflare","Deploy applications and infrastructure to Cloudflare using Workers, Pages, and related platform services. Use when the user asks to deploy, host, publish, or set up a project on Cloudflare.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[873,876,879,882],{"name":874,"slug":875,"type":15},"Cloudflare","cloudflare",{"name":877,"slug":878,"type":15},"Cloudflare Pages","cloudflare-pages",{"name":880,"slug":881,"type":15},"Cloudflare Workers","cloudflare-workers",{"name":861,"slug":862,"type":15},"2026-07-17T06:04:42.853896",{"slug":885,"name":885,"fn":886,"description":887,"org":888,"tags":889,"stars":25,"repoUrl":26,"updatedAt":897},"compose-ui-control","interact with Compose Desktop applications","Control a running Compose Desktop application via HTTP. Use when you need to interact with UI elements, click buttons, enter text, wait for elements to appear, or capture screenshots in a Compose Desktop app that has compose-ui-test-server enabled.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[890,893,896],{"name":891,"slug":892,"type":15},"Automation","automation",{"name":894,"slug":895,"type":15},"Desktop","desktop",{"name":719,"slug":720,"type":15},"2026-07-13T06:40:38.798626",128]