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Covers common pitfalls that break in production: @Transactional self-invocation, N+1 queries, Kotlin + JPA plugins, blocking calls inside WebFlux. Migrating from Boot 3.x? See Setup Check — major breaking changes: Jackson 3 package rename, @MockBean removed, and() in Security DSL removed, Undertow dropped.\"\n---\n\n# Spring Boot Engineer\n\n## Core Workflow\n\n1. **Setup check** — run Setup Check below before writing any code.\n2. **Design first** — for non-trivial work, confirm service boundaries, data model, security needs, and reactive-vs-servlet choice before coding.\n3. **Implement bottom-up** — entity → repository → service → controller. Constructor injection only. Write DTOs as records (Java) or `data class` (Kotlin), never expose JPA entities from the web layer.\n4. **Secure** — `@PreAuthorize` \u002F `SecurityFilterChain`, externalize secrets, validate all input with `@Valid`.\n5. **Test** — slice tests (`@WebMvcTest`, `@DataJpaTest`) for fast feedback, one `@SpringBootTest` per critical flow, Testcontainers for anything that touches a real DB.\n6. **Verify** — run `.\u002Fmvnw test` or `.\u002Fgradlew test` and confirm `\u002Factuator\u002Fhealth` returns `UP` before declaring done.\n\n## Setup Check\n\n**Mandatory before any code change.**\n\n### Step 1 — Is this actually a Spring Boot project?\n\nLook for one of these, in this order:\n\n- `spring-boot-starter-parent` or `spring-boot-dependencies` in `pom.xml`.\n- `org.springframework.boot` plugin in `build.gradle` \u002F `build.gradle.kts`.\n- A class annotated with `@SpringBootApplication`.\n\nIf none → stop and tell the user this isn't a Spring Boot project before proceeding.\n\n### Step 2 — Kotlin project? Verify required compiler plugins.\n\nIf `src\u002Fmain\u002Fkotlin\u002F` exists **and** Spring \u002F JPA is used, both plugins below must be configured. Without them Spring proxies and JPA entities fail at runtime with cryptic errors:\n\n| Plugin | Why it's needed |\n|---|---|\n| `kotlin(\"plugin.spring\")` (`kotlin-spring`) | Opens classes annotated with `@Component` \u002F `@Service` \u002F `@Configuration` \u002F `@Transactional` \u002F `@Async` \u002F `@Cacheable` \u002F `@SpringBootTest` — CGLIB proxies cannot subclass `final` classes. |\n| `kotlin(\"plugin.jpa\")` (`kotlin-jpa`) | Generates a no-arg constructor for `@Entity` \u002F `@Embeddable` \u002F `@MappedSuperclass`. Required for JPA to instantiate entities via reflection. |\n\nIf either is missing → **suggest adding it** before implementing anything that relies on it.\n\n```kotlin\nplugins {\n    kotlin(\"plugin.spring\") version \"\u003Ckotlin-version>\"\n    kotlin(\"plugin.jpa\")    version \"\u003Ckotlin-version>\"\n}\n```\n\nAlso confirm `kotlin-reflect` is on the classpath (included by `spring-boot-starter`).\n\n### Step 3 — Java version & runtime\n\nSpring Boot 4.x requires **Java 17+** (Java 21+ recommended — first-class virtual thread support). Check `\u003Cjava.version>` (Maven) or `java.toolchain` \u002F `sourceCompatibility` (Gradle).\n\nVirtual threads: enable via `spring.threads.virtual.enabled=true`. Don't use them unconditionally — harmful with `synchronized` blocks and `ThreadLocal`-heavy libraries.\n\n**Undertow is no longer supported** in Boot 4 (dropped Servlet 6.1 compatibility). Use Tomcat (default) or Jetty.\n\n### Step 4 — Jackson version\n\nSpring Boot 4 defaults to **Jackson 3**. Most packages were renamed: `com.fasterxml.jackson` → `tools.jackson`. Exception: `jackson-annotations` intentionally keeps the old namespace (`com.fasterxml.jackson.annotation`) for backward compatibility. Any code importing `jackson-databind` or `jackson-core` classes directly will break — update imports. No official compatibility bridge exists; migration must be done manually. If the project already uses Jackson 3 → proceed. If still on Jackson 2 → flag the migration before adding new Jackson-dependent code.\n\n## Reference Guide\n\nLoad on demand — don't read all of these upfront.\n\n| Topic | Reference | Load when |\n|-------|-----------|-----------|\n| Web Layer | `references\u002Fweb.md` | Controllers, DTO boundary, validation, `ProblemDetail`, pagination, CORS, deprecations |\n| Data Access | `references\u002Fdata.md` | JPA \u002F Hibernate pitfalls: N+1, `open-in-view`, `@Transactional` self-invocation, fetch-join + pagination, Hikari tuning |\n| Security | `references\u002Fsecurity.md` | Spring Security 7 `SecurityFilterChain`, CSRF rules, JWT resource server, method security, `\u002Factuator\u002F*` hardening |\n| Testing | `references\u002Ftesting.md` | Test slices (`@WebMvcTest` \u002F `@DataJpaTest` \u002F `@RestClientTest`), `@MockitoBean` migration, Testcontainers + `@ServiceConnection` |\n| Migrations | `references\u002Fmigrations.md` | Flyway \u002F Liquibase, zero-downtime schema change (expand-contract), baseline-on-migrate, `CREATE INDEX CONCURRENTLY` |\n| Scheduling & Observability | `references\u002Fscheduling-observability.md` | `@Scheduled` in a cluster (ShedLock), Actuator exposure, health probes, Micrometer cardinality, virtual threads trade-offs |\n| Kotlin | `references\u002Fkotlin.md` | `kotlin-spring` \u002F `kotlin-jpa` plugins, `@field:` validation, `suspend` controllers, `data class` vs `@Entity` |\n| Event-Driven | `references\u002Fevent-driven.md` | `@TransactionalEventListener`, `@Async` traps, Kafka idempotence, outbox pattern |\n| Resilience | `references\u002Fresilience.md` | Resilience4j annotation order, `fallbackMethod` rules, breaker + retry interaction, distributed vs local rate-limit |\n| Reactive (WebFlux) | `references\u002Freactive.md` | When WebFlux is the right choice, `.block()` traps, `Schedulers.boundedElastic()`, context propagation, backpressure |\n| Cloud Native | `references\u002Fcloud.md` | `spring.config.import` (not `bootstrap.yml`), `@RefreshScope` limits, Gateway on WebFlux, k8s vs Spring Cloud choice |\n\n## Constraints\n\n### MUST DO\n\n| Rule | Correct pattern |\n|------|-----------------|\n| Constructor injection | `public MyService(Dep dep) { this.dep = dep; }` — never `@Autowired` on a field |\n| Validate every mutating endpoint | `@Valid @RequestBody MyRequest req` + Bean Validation annotations on the DTO |\n| DTOs at the web boundary | Java `record` or Kotlin `data class` — **never** return or accept JPA entities directly |\n| Type-safe config | `@ConfigurationProperties(prefix = \"app\")` bound to a record\u002Fclass, not `@Value(\"${…}\")` scattered across the codebase |\n| Correct stereotype | `@Service` for business logic, `@Repository` for data, `@RestController` for HTTP, `@Component` only when nothing else fits |\n| Transaction scope | `@Transactional` only on `public` methods of a Spring-managed bean, called from outside the class (see MUST NOT below) |\n| Read-only hint | `@Transactional(readOnly = true)` on queries — lets Hibernate skip dirty-checking |\n| Rollback on checked exceptions | `@Transactional(rollbackFor = Exception.class)` when the method throws checked exceptions you want to roll back |\n| Global error handling | `@RestControllerAdvice` + `ProblemDetail` (RFC 7807) — never leak stack traces to clients |\n| Externalize secrets | Env vars or Spring Cloud Config — never commit secrets to `application.properties` \u002F `application.yml` |\n| Kotlin + Spring | `kotlin(\"plugin.spring\")` always; `kotlin(\"plugin.jpa\")` when JPA is used |\n| Kotlin validation | `@field:NotBlank` on `data class` properties — bare `@NotBlank` is silently ignored |\n| Post-commit side effects | `@TransactionalEventListener(phase = AFTER_COMMIT)` for email \u002F Kafka \u002F external calls — never inline after a `save()` inside the same transaction |\n\n### MUST NOT — `@Transactional` pitfalls that break in production\n\n- **Self-invocation.** Calling `this.methodWithTransactional()` from another method in the same bean bypasses the proxy — no transaction starts. If you need it, inject `self` (`@Lazy @Autowired MyService self`) or extract the method to a separate bean.\n- **Private \u002F package-private \u002F `final` methods.** Proxies cannot intercept them. `@Transactional` must be on `public` non-`final` methods. (In Kotlin: add `kotlin-spring` plugin so classes\u002Fmethods are open.)\n- **Checked exceptions without `rollbackFor`.** By default Spring rolls back only on `RuntimeException` \u002F `Error`. Declare `@Transactional(rollbackFor = IOException.class)` (or a common superclass) when you want checked exceptions to roll back.\n- **`@Async` + `@Transactional` on the same method.** The async thread doesn't inherit the transaction context — entity becomes detached, you get `LazyInitializationException` or no transaction at all. Split into two beans or use `@TransactionalEventListener(phase = AFTER_COMMIT)`.\n- **Writes inside `readOnly = true`.** Hibernate may skip the flush — your update silently disappears.\n- **`@Transactional` on a `@PostConstruct` method.** Proxy isn't fully initialized yet; the annotation has no effect.\n\n### MUST NOT — general\n\n- Field injection (`@Autowired` on fields) — breaks testability and hides required dependencies.\n- Skipping `@Valid` on API input — request bodies reach your service with whatever the client sent.\n- Using `@Component` when a more specific stereotype fits.\n- Mixing blocking and reactive code: no `.block()` \u002F `.toFuture().get()` inside a `Mono` \u002F `Flux` chain; no blocking JDBC inside a WebFlux controller. Wrap unavoidable blocking calls with `Mono.fromCallable(...).subscribeOn(Schedulers.boundedElastic())`.\n- Storing secrets, connection strings or tokens in `application.properties` \u002F `application.yml` committed to git.\n- Hardcoding URLs \u002F environment-specific values — use profiles (`application-dev.yml`, `application-prod.yml`) and env vars.\n- Removed Boot 3.x deprecated APIs — all of these are gone in Boot 4 and will fail to compile:\n  - `WebSecurityConfigurerAdapter` (use `SecurityFilterChain` bean)\n  - `antMatchers(...)` (use `requestMatchers(...)`)\n  - `WebMvcConfigurerAdapter` (implement `WebMvcConfigurer`)\n  - `and()` in `HttpSecurity` DSL (use separate lambda calls)\n  - `@MockBean` \u002F `@SpyBean` (use `@MockitoBean` \u002F `@MockitoSpyBean`)\n  - `authorizeRequests()` (use `authorizeHttpRequests()`)\n- **Jackson 3 imports**: `com.fasterxml.jackson.*` → `tools.jackson.*`. Don't write new code against Jackson 2 packages on a Boot 4 project.\n- Undertow embedded server — not supported. Don't add `spring-boot-starter-undertow`.\n- Returning or accepting JPA entities at the controller layer — leaks persistence details, causes lazy-loading blowups (`could not initialize proxy — no Session`), breaks API contracts on entity refactors.\n- N+1 queries: `repository.findAll()` followed by accessing `@OneToMany` lazy associations in a loop. Use `@EntityGraph`, `JOIN FETCH`, or projections. See `references\u002Fdata.md`.\n- `spring.jpa.open-in-view=true` in production (the Spring Boot default!). Explicitly set it to `false` — OSIV hides lazy-loading bugs and holds the DB connection for the entire HTTP request.\n\n## Output Format\n\nWhen implementing a new feature, deliver in this order:\n1. Migration (Flyway \u002F Liquibase) if schema changes are needed.\n2. Entity + Repository.\n3. Service with `@Transactional` boundaries.\n4. 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Use ",{"type":44,"tag":95,"props":2094,"children":2096},{"className":2095},[],[2097],{"type":49,"value":2098},"@EntityGraph",{"type":49,"value":154},{"type":44,"tag":95,"props":2101,"children":2103},{"className":2102},[],[2104],{"type":49,"value":2105},"JOIN FETCH",{"type":49,"value":2107},", or projections. See ",{"type":44,"tag":95,"props":2109,"children":2111},{"className":2110},[],[2112],{"type":49,"value":805},{"type":49,"value":136},{"type":44,"tag":63,"props":2115,"children":2116},{},[2117,2123,2125,2131],{"type":44,"tag":95,"props":2118,"children":2120},{"className":2119},[],[2121],{"type":49,"value":2122},"spring.jpa.open-in-view=true",{"type":49,"value":2124}," in production (the Spring Boot default!). Explicitly set it to ",{"type":44,"tag":95,"props":2126,"children":2128},{"className":2127},[],[2129],{"type":49,"value":2130},"false",{"type":49,"value":2132}," — OSIV hides lazy-loading bugs and holds the DB connection for the entire HTTP request.",{"type":44,"tag":52,"props":2134,"children":2136},{"id":2135},"output-format",[2137],{"type":49,"value":2138},"Output Format",{"type":44,"tag":220,"props":2140,"children":2141},{},[2142],{"type":49,"value":2143},"When implementing a new feature, deliver in this order:",{"type":44,"tag":59,"props":2145,"children":2146},{},[2147,2152,2157,2169,2174,2186,2212],{"type":44,"tag":63,"props":2148,"children":2149},{},[2150],{"type":49,"value":2151},"Migration (Flyway \u002F Liquibase) if schema changes are needed.",{"type":44,"tag":63,"props":2153,"children":2154},{},[2155],{"type":49,"value":2156},"Entity + Repository.",{"type":44,"tag":63,"props":2158,"children":2159},{},[2160,2162,2167],{"type":49,"value":2161},"Service with ",{"type":44,"tag":95,"props":2163,"children":2165},{"className":2164},[],[2166],{"type":49,"value":418},{"type":49,"value":2168}," boundaries.",{"type":44,"tag":63,"props":2170,"children":2171},{},[2172],{"type":49,"value":2173},"DTOs (request + response) as records \u002F data classes.",{"type":44,"tag":63,"props":2175,"children":2176},{},[2177,2179,2184],{"type":49,"value":2178},"Controller + ",{"type":44,"tag":95,"props":2180,"children":2182},{"className":2181},[],[2183],{"type":49,"value":1441},{"type":49,"value":2185}," entries for new exception types.",{"type":44,"tag":63,"props":2187,"children":2188},{},[2189,2191,2196,2198,2203,2205,2210],{"type":49,"value":2190},"Tests: one ",{"type":44,"tag":95,"props":2192,"children":2194},{"className":2193},[],[2195],{"type":49,"value":160},{"type":49,"value":2197}," for repository custom queries, one ",{"type":44,"tag":95,"props":2199,"children":2201},{"className":2200},[],[2202],{"type":49,"value":152},{"type":49,"value":2204}," per controller, one ",{"type":44,"tag":95,"props":2206,"children":2208},{"className":2207},[],[2209],{"type":49,"value":168},{"type":49,"value":2211}," for the full happy path.",{"type":44,"tag":63,"props":2213,"children":2214},{},[2215],{"type":49,"value":2216},"One-line summary of the key architectural decisions (why this transaction boundary, why this projection, why this status code).",{"type":44,"tag":2218,"props":2219,"children":2220},"style",{},[2221],{"type":49,"value":2222},"html .light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html.light .shiki span {color: var(--shiki-light);background: var(--shiki-light-bg);font-style: var(--shiki-light-font-style);font-weight: var(--shiki-light-font-weight);text-decoration: var(--shiki-light-text-decoration);}html .default .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .shiki span {color: var(--shiki-default);background: var(--shiki-default-bg);font-style: var(--shiki-default-font-style);font-weight: var(--shiki-default-font-weight);text-decoration: var(--shiki-default-text-decoration);}html .dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}html.dark .shiki span {color: var(--shiki-dark);background: var(--shiki-dark-bg);font-style: var(--shiki-dark-font-style);font-weight: var(--shiki-dark-font-weight);text-decoration: var(--shiki-dark-text-decoration);}",{"items":2224,"total":2353},[2225,2241,2250,2259,2270,2280,2293,2302,2311,2321,2330,2343],{"slug":2226,"name":2226,"fn":2227,"description":2228,"org":2229,"tags":2230,"stars":2238,"repoUrl":2239,"updatedAt":2240},"mps-aspect-accessories","configure JetBrains MPS module dependencies","Wire MPS module and model dependencies, used languages, used devkits, extended languages, runtime solutions, accessory models, and language\u002Fdependency versions. 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},[2231,2234,2237],{"name":2232,"slug":2233,"type":15},"Architecture","architecture",{"name":2235,"slug":2236,"type":15},"Configuration","configuration",{"name":26,"slug":27,"type":15},1650,"https:\u002F\u002Fgithub.com\u002FJetBrains\u002FMPS","2026-07-17T06:06:57.311661",{"slug":2242,"name":2242,"fn":2243,"description":2244,"org":2245,"tags":2246,"stars":2238,"repoUrl":2239,"updatedAt":2249},"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},[2247,2248],{"name":2232,"slug":2233,"type":15},{"name":26,"slug":27,"type":15},"2026-07-17T06:04:48.066901",{"slug":2251,"name":2251,"fn":2252,"description":2253,"org":2254,"tags":2255,"stars":2238,"repoUrl":2239,"updatedAt":2258},"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},[2256,2257],{"name":2232,"slug":2233,"type":15},{"name":26,"slug":27,"type":15},"2026-07-13T06:45:21.757084",{"slug":2260,"name":2260,"fn":2261,"description":2262,"org":2263,"tags":2264,"stars":2238,"repoUrl":2239,"updatedAt":2269},"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},[2265,2266],{"name":2232,"slug":2233,"type":15},{"name":2267,"slug":2268,"type":15},"Code Analysis","code-analysis","2026-07-23T05:41:33.639365",{"slug":2271,"name":2271,"fn":2272,"description":2273,"org":2274,"tags":2275,"stars":2238,"repoUrl":2239,"updatedAt":2279},"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},[2276],{"name":2277,"slug":2278,"type":15},"Data Analysis","data-analysis","2026-07-13T06:45:19.114674",{"slug":2281,"name":2281,"fn":2282,"description":2283,"org":2284,"tags":2285,"stars":2238,"repoUrl":2239,"updatedAt":2292},"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},[2286,2289],{"name":2287,"slug":2288,"type":15},"Design","design",{"name":2290,"slug":2291,"type":15},"UI Components","ui-components","2026-07-23T05:41:56.638151",{"slug":2294,"name":2294,"fn":2295,"description":2296,"org":2297,"tags":2298,"stars":2238,"repoUrl":2239,"updatedAt":2301},"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},[2299,2300],{"name":26,"slug":27,"type":15},{"name":2290,"slug":2291,"type":15},"2026-07-23T05:41:49.666535",{"slug":2303,"name":2303,"fn":2304,"description":2305,"org":2306,"tags":2307,"stars":2238,"repoUrl":2239,"updatedAt":2310},"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},[2308,2309],{"name":2232,"slug":2233,"type":15},{"name":26,"slug":27,"type":15},"2026-07-13T06:44:59.507855",{"slug":2312,"name":2312,"fn":2313,"description":2314,"org":2315,"tags":2316,"stars":2238,"repoUrl":2239,"updatedAt":2320},"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},[2317,2318,2319],{"name":2232,"slug":2233,"type":15},{"name":2267,"slug":2268,"type":15},{"name":26,"slug":27,"type":15},"2026-07-17T06:06:58.042999",{"slug":2322,"name":2322,"fn":2323,"description":2324,"org":2325,"tags":2326,"stars":2238,"repoUrl":2239,"updatedAt":2329},"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},[2327,2328],{"name":2232,"slug":2233,"type":15},{"name":26,"slug":27,"type":15},"2026-07-23T05:41:48.692899",{"slug":2331,"name":2331,"fn":2332,"description":2333,"org":2334,"tags":2335,"stars":2238,"repoUrl":2239,"updatedAt":2342},"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},[2336,2339],{"name":2337,"slug":2338,"type":15},"Debugging","debugging",{"name":2340,"slug":2341,"type":15},"Migration","migration","2026-07-13T06:45:20.372122",{"slug":2344,"name":2344,"fn":2345,"description":2346,"org":2347,"tags":2348,"stars":2238,"repoUrl":2239,"updatedAt":2352},"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},[2349],{"name":2350,"slug":2351,"type":15},"Data Modeling","data-modeling","2026-07-23T05:41:30.705975",188,{"items":2355,"total":2449},[2356,2370,2385,2395,2407,2422,2432],{"slug":2357,"name":2357,"fn":2358,"description":2359,"org":2360,"tags":2361,"stars":28,"repoUrl":29,"updatedAt":2369},"android","build Android applications with Kotlin","Senior Android engineer workflows — Kotlin-first (Java legacy supported), Jetpack Compose + View system, MVVM, Coroutines\u002FFlow, Room, Retrofit, Hilt, plus device orchestration via plugin tools (device management, logcat, crash reports, app run) and mobile-mcp for UI interaction (element tree, taps, swipes). Use when implementing features, debugging crashes, fixing builds, writing tests, reviewing Android code, or running QA on an emulator.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2362,2364,2365,2366],{"name":2363,"slug":2357,"type":15},"Android",{"name":26,"slug":27,"type":15},{"name":13,"slug":14,"type":15},{"name":2367,"slug":2368,"type":15},"Mobile","mobile","2026-07-13T06:45:38.239419",{"slug":2371,"name":2371,"fn":2372,"description":2373,"org":2374,"tags":2375,"stars":28,"repoUrl":29,"updatedAt":2384},"context7","search library and framework documentation","Up-to-date library and framework documentation via Context7 MCP. Use when setup, API, or version-specific questions require current documentation.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2376,2379,2382],{"name":2377,"slug":2378,"type":15},"Documentation","documentation",{"name":2380,"slug":2381,"type":15},"MCP","mcp",{"name":750,"slug":2383,"type":15},"reference","2026-07-17T06:07:06.49579",{"slug":2386,"name":2386,"fn":2387,"description":2388,"org":2389,"tags":2390,"stars":28,"repoUrl":29,"updatedAt":2394},"java-engineer","write and refactor modern Java code","Java 17–25 policy and pitfalls. Use when writing, reviewing, or refactoring Java code — enforces idioms around records, sealed types, switch exhaustiveness, Optional, virtual threads, and null-safety that LLMs frequently get wrong.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2391,2392,2393],{"name":2267,"slug":2268,"type":15},{"name":26,"slug":27,"type":15},{"name":20,"slug":21,"type":15},"2026-07-13T06:45:44.594223",{"slug":2396,"name":2396,"fn":2397,"description":2398,"org":2399,"tags":2400,"stars":28,"repoUrl":29,"updatedAt":2406},"kotlin-engineer","write and refactor Kotlin code","Kotlin 2.x policy and pitfalls. Use when writing, reviewing, or refactoring Kotlin code — enforces coroutine-safety, Flow correctness, null-safety, and API-design rules that LLMs frequently get wrong.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2401,2404,2405],{"name":2402,"slug":2403,"type":15},"Code Review","code-review",{"name":26,"slug":27,"type":15},{"name":13,"slug":14,"type":15},"2026-07-13T06:45:30.911318",{"slug":2408,"name":2408,"fn":2409,"description":2410,"org":2411,"tags":2412,"stars":28,"repoUrl":29,"updatedAt":2421},"laravel-engineer","build and architect Laravel applications","Use when working on Laravel projects. Covers architecture decisions (Services vs Actions), thin controllers, Form Requests, API Resources, and API versioning. Enforces Larastan verification after code generation.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2413,2414,2415,2418],{"name":17,"slug":18,"type":15},{"name":26,"slug":27,"type":15},{"name":2416,"slug":2417,"type":15},"Laravel","laravel",{"name":2419,"slug":2420,"type":15},"PHP","php","2026-07-13T06:45:47.16012",{"slug":2423,"name":2423,"fn":2424,"description":2425,"org":2426,"tags":2427,"stars":28,"repoUrl":29,"updatedAt":2431},"php-engineer","write and refactor modern PHP code","Modern PHP 8.x policy and pitfalls. Use when writing, reviewing, or refactoring PHP code — enforces strict types, enum\u002Freadonly\u002Fmatch\u002FDNF policy, PHPStan discipline, and catches the subtle traps (type coercion, mixed abuse, readonly mutation through references, enum serialization, fiber lifecycle, PDO emulation) that LLMs get wrong by default.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2428,2429,2430],{"name":2267,"slug":2268,"type":15},{"name":26,"slug":27,"type":15},{"name":2419,"slug":2420,"type":15},"2026-07-13T06:45:32.210657",{"slug":2433,"name":2433,"fn":2434,"description":2435,"org":2436,"tags":2437,"stars":28,"repoUrl":29,"updatedAt":2448},"redis-best-practices","implement Redis best practices","Redis policy & pitfalls — key naming, atomicity, TTL strategy, distributed locks, cache patterns, production traps. Use when designing Redis-backed caches, locks, queues, rate limiters, or sessions. Covers the traps LLMs get wrong by default: SETNX + EX (deprecated), KEYS on production, Pub\u002FSub no-persistence, HGETALL on big hashes, maxmemory-policy defaults, cluster hash tags, RDB fork memory.",{"slug":8,"name":9,"logoUrl":10,"githubOrg":9},[2438,2441,2442,2445],{"name":2439,"slug":2440,"type":15},"Database","database",{"name":26,"slug":27,"type":15},{"name":2443,"slug":2444,"type":15},"Performance","performance",{"name":2446,"slug":2447,"type":15},"Redis","redis","2026-07-13T06:45:48.502742",9]