gradle-developer

name	gradle-developer
description	Expert guide for Gradle 9 builds in apache/grails-core on the 8.0.x line - multi-project topology, convention plugins, BOM platforms, dependency rules, task configuration hygiene, and repo-specific patterns that override generic Gradle docs
license	Apache-2.0

What I Do

• Write and change Gradle build scripts the way this repository already does them on 8.0.x (Gradle 9.6.x).
• Keep agents off generic Gradle "best practice" when it conflicts with established monorepo patterns.
• Cover composite builds (build-logic, grails-gradle, grails-forge, end-to-end), convention plugins, BOM/platform() dependency management, test wiring, publishing hooks, and Gradle 9 task-configuration traps learned from recent PRs.
• Make Gradle changes boring, copy-paste consistent, and correct on the first try.

When to Use Me

MANDATORY before any of the following:

• Editing build.gradle, settings.gradle, gradle.properties, dependencies.gradle, or anything under gradle/, build-logic/, grails-gradle/
• Adding or renaming a module / subproject
• Bumping a dependency version or the Gradle wrapper
• Changing test, publish, SBOM, code-style, or JaCoCo Gradle wiring
• Touching Grails Gradle plugins used by apps (org.apache.grails.gradle.*)
• Diagnosing configuration-cache, resolution, afterEvaluate, or task-graph failures

Also load when a change looks like application code but requires build script updates (new module, new published artifact, CLI companion jar, functional test app).

Related skills (do not substitute this one):

Need	Skill
CodeNarc / Checkstyle / PMD / SpotBugs reports	violation-fixer
Failing tests / aggregate reports	test-fixer
Merging an external plugin repo into the monorepo	mono-repo-integration
App-facing Grails 8 upgrade guidance	grails-8-upgrade

---

Prime Directive: This Repo Wins

1. Match neighboring modules. Before inventing structure, open 2-3 similar build.gradle files and copy their plugin block, dependency style, and apply { from ... } scripts.
2. Prefer existing convention plugins over inline configuration. If CompilePlugin already sets encoding, release, jars, and reproducibility, do not re-declare those in the module script.
3. Gradle docs are secondary. Official Gradle 9 docs are useful for APIs and deprecations, but this monorepo intentionally diverges (configuration cache off, no Spring DM plugin, heavy projectDir remapping, presence-based -P flags, custom BOM validator). When docs and this repo disagree, follow this repo unless you are deliberately fixing a known issue with a tracked reason.
4. Do not use io.spring.dependency-management / Spring Dependency Management plugin in core modules or applications. The intentional regression fixture at grails-test-examples/spring-dependency-management is the only exception. Grails 8 otherwise uses native platform() / enforcedPlatform() plus org.apache.grails.gradle.bom-property-overrides (see PR #15467).
5. Scope Gradle invocations to the touched subproject (:module:test, not root test) unless the change is cross-cutting.

Change workflow

1. Inspect 2-3 sibling modules and the relevant convention plugin or shared script.
2. Confirm the Gradle project path in settings.gradle, including any projectDir mapping.
3. Edit the smallest appropriate build file or convention plugin.
4. Run scoped compile, test, and validateDependencyVersions tasks for the changed project.
5. For grails-gradle changes, run the relevant plugin TestKit tests from grails-gradle/ with its wrapper.

---

Topology (Know Where You Are)

This git repo is several independent Gradle builds, not one flat multiproject:

Build	Path	Role	How to run
Root framework	repo root	60+ published modules, BOMs, test-examples, profiles, docs	./gradlew … from root
build-logic	build-logic/	Shared convention plugins via includeBuild	cd build-logic && ./gradlew … (or root pluginManagement includeBuild)
grails-gradle	grails-gradle/	Published Grails Gradle plugins for apps	cd grails-gradle && ./gradlew …
grails-forge	grails-forge/	App generator (own wrapper, own deps)	cd grails-forge && ./gradlew …
end-to-end	end-to-end/	Tests against published artifacts in build/local-maven	Full 3-step flow below (see end-to-end/README.md)
gradle-bootstrap	gradle-bootstrap/	Regenerates shared wrappers from .sdkmanrc	gradle -p gradle-bootstrap (see wrapper section)

end-to-end is not a composite consumer of the root build. It resolves real published coordinates from <repo>/build/local-maven (the TestCaseMavenRepo), not ~/.m2 and not via publishAllToMavenLocal. Do not add includeBuild('..') substitution - that defeats validating consumer metadata, CLI companions, and POM/BOM shape.

Full local run (three steps, in order):

# 1) Publish grails-gradle + root into build/local-maven (both required)
(cd grails-gradle && ./gradlew publishAllPublicationsToTestCaseMavenRepoRepository)
./gradlew publishAllPublicationsToTestCaseMavenRepoRepository

# 2) Build the standalone Grails 7 fixture jar (JDK 17 / Gradle 8.x via its .sdkmanrc)
cd end-to-end/legacy-g7-command-plugin
sdk env
./gradlew jar
cd ../..

# 3) Run the suite on the root JDK 21 environment
sdk env   # from repository root (.sdkmanrc)
cd end-to-end
./gradlew check

Leave legacy-g7-command-plugin's wrapper on its pinned Grails 7 Gradle version when bumping the main line.

Root settings.gradle wires:

pluginManagement {
    includeBuild('./grails-gradle') { name = 'grails-gradle' }
    includeBuild('./build-logic') { name = 'build-logic-root' }
    // ...
}

build-logic exists because composite builds do not share buildSrc plugins. Internal conventions live there so root, grails-gradle, and forge can consume them.

Project path != directory name

Root settings heavily remaps projectDir (100+ entries). Examples:

Gradle path	Directory
:grails-bom	grails-bom/default
:grails-base-bom	grails-bom/base
:grails-hibernate7-bom	grails-bom/hibernate7
:grails-controllers	grails-controllers (often 1:1)
:grails-data-hibernate7-core	grails-data-hibernate7/core
:grails-test-examples-app1	grails-test-examples/app1

Always use the Gradle project path in task names (./gradlew :grails-data-hibernate7-core:test). Confirm with settings.gradle include + projectDir when unsure. Do not invent paths from folder names alone.

Micronaut "island"

grails-micronaut*, micronaut BOMs, and related test-examples are gated in settings.gradle:

• Auto-excluded on JDK < 25 (Micronaut 5 targets JVM 25 bytecode)
• Auto-included on JDK 25+
• -PskipMicronautProjects forces exclude (used by groovy-joint CI)
• -PincludeMicronautProjects forces include on older JDKs (still may not compile)

Presence-based flags (property present, value optional) match skipFunctionalTests / skipCodeStyle style elsewhere.

---

Gradle Version Sync (Hard Rule)

Current line: Gradle 9.6.0 (distributionUrl + gradleToolingApiVersion=9.6.0). Upstream may already ship a newer 9.6.x patch - this repo rides close to latest only after a deliberate multi-location bump PR. Do not "helpfully" jump one wrapper ahead of the rest.

Two Groovy stacks: Gradle itself embeds Groovy 4 for build logic. Application/runtime code on 8.0.x is Groovy 5. That is why dependencies.gradle keeps separate maps:

• gradleBomDependencyVersions / gradle-groovy.version / gradle-spock.version → build tooling (Groovy 4 / Spock groovy-4)
• bomDependencyVersions / groovy.version / spock.version → apps and framework modules (Groovy 5 / Spock groovy-5.0)

Never unify those casually.

Preferred bump workflow

1. Set the new Gradle version in .sdkmanrc (gradle=…).

2. Run the bootstrap project (uses a system gradle to regenerate shared wrappers from .sdkmanrc):

   gradle -p gradle-bootstrap
   

   Bootstrap generates the wrapper under gradle-bootstrap/, copies it to grails-forge, grails-gradle, and end-to-end, then moves the generated wrapper into the repository root. It also runs legacyG7Wrapper so end-to-end/legacy-g7-command-plugin stays on its pinned Grails 7 Gradle version (currently 8.x - do not force it to 9). Root is therefore bootstrap-covered; do not re-list it as a manual step.

3. Manually refresh the locations bootstrap does not cover. For each tree, keep the full wrapper set in sync (gradle-wrapper.properties, gradle-wrapper.jar, gradlew, gradlew.bat) - not properties alone:

   • build-logic/ - run its wrapper task or copy the complete set from root after bootstrap
   • grails-profiles/base/skeleton/ and grails-profiles/profile/skeleton/
   • grails-shell-cli/src/test/resources/gradle-sample/ (and bin/test copy if present)
   • Forge generated-app wrapper assets (all of these - properties alone is not enough):
     • grails-forge/grails-forge-core/.../gradleWrapperProperties.rocker.raw (properties template)
     • grails-forge/grails-forge-core/src/main/resources/gradle/gradlew
     • grails-forge/grails-forge-core/src/main/resources/gradle/gradlew.bat
     • grails-forge/grails-forge-core/src/main/resources/gradle/wrapper/gradle-wrapper.jar
   • gradle.properties → gradleToolingApiVersion (must match the new Gradle version)

4. Verify every main-line tree matches on properties and scripts/jars. The only intentional holdout is (Gradle 8.x).

Also keep gradlew.bat LF line endings on this line (PR #15709). Comment at top of root gradle-wrapper.properties remains a human checklist.

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Root gradle.properties Flags (Do Not "Fix" Blindly)

Property	Value / note
org.gradle.caching	true
org.gradle.parallel	true
org.gradle.daemon	true
org.gradle.configuration-cache	false until #15497 resolved - do not enable casually
org.gradle.configureondemand	commented off - Gradle issue #9489
org.gradle.jvmargs	-Xmx5G (raise only with reason; groovydoc is hungry)
javaVersion	21 (CompilePlugin reads this for --release)
projectVersion	framework version
slf4jPreventExclusion	true - Grails Gradle plugin POM behavior

CI vs local behavior is branched on System.getenv('CI') and SOURCE_DATE_EPOCH (reproducible builds disable remote cache).

---

Standard Published Library Module

Canonical pattern (see grails-core/build.gradle, grails-controllers/build.gradle, grails-services/build.gradle):

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  ... Apache header ...
 */

plugins {
    id 'groovy'
    id 'java-library'
    id 'project-report'                                      // optional but common
    id 'org.apache.grails.buildsrc.properties'
    id 'org.apache.grails.buildsrc.dependency-validator'
    id 'org.apache.grails.buildsrc.compile'
    id 'org.apache.grails.buildsrc.publish'
    id 'org.apache.grails.buildsrc.sbom'
    id 'org.apache.grails.buildsrc.vulnerability-scan'      // when appropriate
    id 'org.apache.grails.gradle.grails-code-style'
    id 'org.apache.grails.gradle.grails-jacoco'
}

version = projectVersion
group = 'org.apache.grails'   // or org.apache.grails.web / .data / etc. - match siblings

dependencies {
    implementation platform(project(':grails-bom'))   // or :grails-hibernate7-bom, etc.

    api project(':grails-core')
    api 'org.apache.groovy:groovy'
    // versions come from the platform - do NOT hardcode versions here

    compileOnly 'jakarta.servlet:jakarta.servlet-api'

    testImplementation 'org.spockframework:spock-core'
    testImplementation 'org.apache.groovy:groovy-test-junit5'
    testImplementation 'org.junit.jupiter:junit-jupiter-api'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'
    // junit-platform-launcher is added by gradle/test-config.gradle
}

apply {
    from rootProject.layout.projectDirectory.file('gradle/docs-config.gradle')
    from rootProject.layout.projectDirectory.file('gradle/test-config.gradle')
}

Rules for module scripts

• Apache license header on every new .gradle / .gradle.kts file.
• Prefer Groovy DSL (this repo is almost entirely .gradle, not .kts).
• version = projectVersion and explicit group - do not invent version schemes per module.
• Use rootProject.layout.projectDirectory.file('gradle/…') for shared scripts (lazy layout API), not brittle rootProject.file string soup in new code.
• Prefer tasks.named('x') / tasks.withType(T).configureEach over eager task x << or bare tasks.x { } mutation when touching existing modernized code.
• Configuration avoidance: do not call .get() on providers during configuration unless required; do not resolve configurations at configuration time.
• api vs implementation vs compileOnly vs runtimeOnly vs testImplementation - follow Java Library plugin semantics; public types in your API surface → api.
• Project deps: project(':grails-foo') using the settings path.
• External deps: coordinate without version when the BOM manages them.

CLI companion modules

Command-bearing modules may apply org.apache.grails.gradle.grails-plugin-cli and declare cliApi / cliImplementation configurations (PR #15948). Framework modules that wire CLI with project deps set ext.grailsCliAutoProvision = false (root build.gradle does this for non-test-example projects). Do not dump CLI-only deps back onto the main runtime classpath.

---

Functional / Test-Example Apps

See grails-test-examples/app1/build.gradle:

• Apply Grails app plugins: org.apache.grails.gradle.grails-web, often org.apache.grails.gradle.grails-gsp, and cloud.wondrify.asset-pipeline
• Still use implementation platform(project(':grails-bom'))
• Depend on published coordinates (org.apache.grails:grails-dependencies-starter-web) - root applies dependency substitution via gradle/functional-test-config.gradle so local projects replace Maven coordinates
• Apply gradle/functional-test-config.gradle (and datastore-specific scripts like hibernate7-test-config.gradle when needed)
• Do not disable substitution without understanding multi-project resolution

---

Dependency Management (BOM Is Law)

Single source of versions

File	What it owns
Root dependencies.gradle	Application/runtime BOM versions (bomDependencyVersions, bomDependencies, bomPlatformDependencies) and gradle-tooling maps (gradleBomDependencyVersions, etc.). grails-gradle applies this same file via ../dependencies.gradle - there is no separate grails-gradle/dependencies.gradle on this line
gradle.properties	Non-BOM pins (tool versions, javaVersion, gradleToolingApiVersion, checkstyle/codenarc/pmd/jacoco versions)

No gradle/libs.versions.toml. This monorepo does not use Gradle version catalogs. Do not introduce a catalog "because Gradle docs recommend it." Dependabot and the published BOM pipeline are built around the root dependencies.gradle maps (see comment at top of that file).

Map naming contract

For POM property generation, map key must be the dependency name prefix:

bomDependencyVersions = [
    'groovy.version': '5.0.7',
]
bomDependencies = [
    'groovy': "org.apache.groovy:groovy:${bomDependencyVersions['groovy.version']}",
]

Break this and published BOM properties / docs extraction break.

Platform usage in modules

// Default
implementation platform(project(':grails-bom'))

// Hibernate 7 stack
implementation platform(project(':grails-hibernate7-bom'))

// Micronaut variants use enforcedPlatform in app-facing plugin logic

grails-bom/base (:grails-base-bom) is a java-platform that:

• Imports Spring Boot BOM via api platform(...) (with deliberate excludes for groovy/spock/hibernate/liquibase where Grails owns the line)
• Adds constraints from dependencies.gradle maps
• Adds constraints for published subprojects
• Applies gradle/cli-companion-bom-constraints.gradle for CLI companion versions under enforcedPlatform

validateDependencyVersions (AGENTS.md rule 14 / dependency-validator plugin)

Applied via org.apache.grails.buildsrc.dependency-validator.

Implementation detail (GrailsDependencyValidatorPlugin): for each resolved coordinate that the BOM also manages, it fails when bomVersion != resolvedVersion - any mismatch, not only "resolved is newer."

How to fix by direction:

Situation	Fix
Transitive resolved newer than BOM	Bump the pin in dependencies.gradle so the BOM is >= the winner (usual case; AGENTS.md rule 14)
Resolved older / forced / strict conflict	Find the force, strict constraint, or second platform pulling the other version; remove the force, align platforms, or document a deliberate override
Intentional divergence that must stay	ext.allowedBomOverrides = ['group:name', …] with a commented reason - last resort
Whole project cannot validate	Prefer ext.skipDependencyValidation = true in the build script. CLI: -PskipDependencyValidation is presence-based and skips validation; -PskipDependencyValidation=true is also valid. Use the documented form that best communicates intent.

Also:

• Prefer inheriting Spring Boot managed versions over re-pinning duplicates (PR #15730). Only pin when diverging (security override, missing from Boot BOM, lockstep companion like graphql-java-extended-scalars).
• Same coordinate managed in multiple BOM maps must use the same version everywhere or enforcedPlatform resolution explodes.
• Do not silence validation with exclusions as a shortcut to avoid a BOM bump.

Adding or bumping a dependency

1. Decide if Spring Boot already manages it - if same version, omit pin.
2. If Grails must manage it, add/bump in the correct map in dependencies.gradle.
3. Use the unversioned coordinate in module dependencies {}.
4. Run ./gradlew :that-module:validateDependencyVersions (and affected consumers).
5. Security overrides: comment with CVE and previous Boot version (see existing httpcore5/jackson/logback pins).

Exclusions

Use sparingly, always with a reason. Common pattern for Hibernate:

api 'org.hibernate.orm:hibernate-core', {
    exclude group: 'commons-logging', module: 'commons-logging'
    // ...
}

Do not exclude your way out of a BOM version fight. Prefer the direction-aware fixes in the validator table above (usually bump the BOM when a transitive is newer; otherwise align forces/platforms).

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Convention Plugins (build-logic)

Plugin IDs (implementation under build-logic/plugins/…/buildsrc/):

Plugin ID	Purpose
org.apache.grails.buildsrc.properties	Load root/local.properties into ext
org.apache.grails.buildsrc.compile	Java 21 --release, UTF-8, fork memory, parameters, sources/javadoc jars, reproducible archives, Groovy config script, isolated build, per-project base.dir
org.apache.grails.buildsrc.dependency-validator	validateDependencyVersions
org.apache.grails.buildsrc.publish	Publishing conventions (grails-publish integration)
org.apache.grails.buildsrc.sbom	CycloneDX / SBOM reproducibility
org.apache.grails.buildsrc.vulnerability-scan	OSS Index style scanning hooks
org.apache.grails.buildsrc.groovydoc	Groovydoc
org.apache.grails.buildsrc.groovydoc-enhancer	Groovydoc enhancer
org.apache.grails.buildsrc.repo	Settings plugin: Apache snapshot/staging repo content filters
org.apache.grails.gradle.grails-code-style	Checkstyle + CodeNarc
org.apache.grails.gradle.grails-code-analysis	PMD + SpotBugs (opt-in props)
org.apache.grails.gradle.grails-jacoco	JaCoCo per project
org.apache.grails.gradle.grails-violation-aggregation	Root only - aggregateViolations
org.apache.grails.gradle.grails-ij-formatter	IntelliJ formatter wiring

CompilePlugin behaviors you must not fight

• JavaCompile.options.release from javaVersion (21) - not outdated sourceCompatibility/targetCompatibility pairs in new code
• UTF-8 everywhere
• -parameters for reflection/IDE
• Forked compilation with -Dgrails.isolated.build=true and a per-project BaseDirArgumentProvider supplying -Dbase.dir=<projectDir>. It is marked @Internal, not @InputDirectory, because projectDir contains build outputs. Do not remove it: it prevents grails.factories leaking between compiler daemons (#15799 / CompilePlugin comments).
• The compile-time base.dir provider is required, but absolute base.dir values are forbidden in Test.systemProperties: they make cache keys machine-specific. Never "simplify" by removing the compiler provider or adding an absolute test property.
• Jar.duplicatesStrategy = FAIL - duplicate entries are configuration bugs
• Reproducible archives: no timestamps, fixed order, unix 0644/0755
• Groovy configurationScript → gradle/groovy-compile-configscript.groovy (annotation member order / GROOVY-12146 workaround, PR #15963)

Published Grails Gradle plugins (grails-gradle)

Use the fully qualified plugin IDs in plugins { id '…' } blocks. Most are registered in grails-gradle/plugins/build.gradle. org.apache.grails.gradle.grails-publish is supplied by the external grails-publish-plugin implementation dependency (not listed in that file's gradlePlugin {} block) but is still the correct ID for publishing.

Plugin ID
org.apache.grails.gradle.grails-app
org.apache.grails.gradle.grails-web
org.apache.grails.gradle.grails-plugin
org.apache.grails.gradle.grails-gsp
org.apache.grails.gradle.grails-gson
org.apache.grails.gradle.grails-markup
org.apache.grails.gradle.grails-profile
org.apache.grails.gradle.grails-publish-profile
org.apache.grails.gradle.grails-cli
org.apache.grails.gradle.grails-plugin-cli
org.apache.grails.gradle.grails-cli-library
org.apache.grails.gradle.grails-exploded
org.apache.grails.gradle.grails-integration-test
org.apache.grails.gradle.grails-test-phases
org.apache.grails.gradle.bom-property-overrides
org.apache.grails.gradle.grails-publish (via grails-publish-plugin dependency)

Never paste bare suffixes like grails-web into a plugins block - resolution will fail.

When changing these plugins:

• Prefer lazy task configuration; never resolve configurations inside configureEach at configuration time (PR #16076 - Gradle 9.5+ markAsObserved failures).
• Be careful with nested afterEvaluate ordering (PR #16009 - BOM apply vs CLI detect race).
• Declare Copy/processResources filter values as task inputs (PR #16006 - ReplaceTokens up-to-date bug).
• Functional tests live under grails-gradle/plugins/src/test with TestKit projects - update them with behavior changes.
• Build/test from grails-gradle/ directory with its wrapper.

---

Shared Scripts Under gradle/

Apply with:

apply {
    from rootProject.layout.projectDirectory.file('gradle/test-config.gradle')
}

Script	Use
test-config.gradle	JUnit Platform, parallel forks, heap, cache policy, skip flags, launcher deps
functional-test-config.gradle	Dependency substitution for test-examples
docs-config.gradle / docs-dependencies.gradle	Groovydoc / docs classpaths
publish-root-config.gradle	Root publishing orchestration
rat-root-config.gradle	Apache RAT
cli-companion-bom-constraints.gradle	CLI artifact constraints on BOMs
hibernate5-test-config.gradle / hibernate7-test-config.gradle	Datastore test stacks
spring-security-test-config.gradle	Spring Security functional and integration tests
grails-data-tck-config.gradle	GORM data TCK wiring and test filters
grails-extension-gradle-config.gradle	Gradle extension module conventions
test-webjar-asset-config.gradle	WebJar asset test setup
mongodb-forked-test-config.gradle	Forked MongoDB test configuration
mongodb-*-test-config.gradle / redis-test-config.gradle	External service tests
plugin-repositories.gradle	Shared plugin repo config for settings
groovy-compile-configscript.groovy	Groovy compiler config script (not applied via apply from in modules - referenced by CompilePlugin)

Test flags (test-config.gradle)

Presence of project properties skips/selects suites, e.g.:

skipTests, skipCoreTests, onlyFunctionalTests, onlyHibernate5Tests, onlyHibernate7Tests, onlyMongodbTests, onlyRedisTests, onlySpringSecurityTests

Parallelism: configuredTestParallel from -PmaxTestParallel or CI default 3 / local availableProcessors * 3/4.

Env:

• DO_NOT_CACHE_TESTS=1 - force test re-run without full --rerun-tasks
• debug.tests system prop - attach debugger args
• SUPPRESS_DEPRECATION_WARNINGS=true - strip some -Xlint noise

CI disables build cache for GroovyCompile and Test so AST transforms and tests stay honest.

---

Configuration Hygiene (Gradle 9.x Landmines)

These bit this repo in production PRs. Treat as hard rules when writing plugin or build code:

1. No configuration-time classpath resolution in task configureEach callbacks. Defer probes to execution (doFirst / task actions) or use proper providers (PR #16076).
2. No nested afterEvaluate that mutates configurations after another plugin may have resolved a related configuration (PR #16009). Prefer withPlugin / plugins.withId / lazy configurations.configureEach before observation.
3. Task inputs must include filter/token maps and any other non-file data that affects outputs (PR #16006).
4. All custom task types must declare caching intent (@DisableCachingByDefault or correct cacheable annotations) - required since Gradle 9 upgrade (PR #15365).
5. Prefer JavaPluginExtension over deprecated JavaPluginConvention; destinationFile over outputFile on WriteProperties; avoid ConfigureUtil / old convention APIs.
6. Tests need junit-platform-launcher on testRuntimeOnly (shared script adds it) - Gradle 9 requirement.
7. Do not enable configuration cache or configure-on-demand in this repo without an issue-linked plan.
8. evaluationDependsOn appears in BOM/docs scripts for a reason - do not cargo-cult it into random modules; it couples configuration order and slows builds.

Build Cacheability

The local build cache is enabled. Treat cacheability as a correctness constraint, not a later optimization.

Rule	Why / practice
Do not put absolute machine paths, especially base.dir, in Test.systemProperties	They poison cache keys across machines (#15483). The compiler's @Internal BaseDirArgumentProvider is the separate, required compile-time case.
Avoid doFirst and custom actions on cacheable tasks	They can make a task ineligible for the build cache. Prefer a dedicated task with declared inputs and outputs or model the I/O properly. Some tradeoffs are intentional: GroovyDoc compatibility with configuration cache and selected GroovyCompile doFirst actions in GrailsGradlePlugin.
Give compiler configuration and reports task-specific paths	Overlapping outputs disable caching. Use names such as grailsGroovyCompilerConfig-{taskName}.groovy and separate Checkstyle / CodeNarc report paths (#15532).
Do not use outputs.upToDateWhen to bypass work when it also prevents cache loading	Model inputs and outputs instead. Keep GSP outputs separate, for example gsp-classes/main versus webapp (#15537).
Normalize generated unstable files packed into jars or classpaths	SbomPlugin uses normalization.runtimeClasspath.ignore("META-INF/sbom.json"). Add comparable normalization so unstable generated contents do not cascade cache misses.

Use Develocity experiments to prove a change: populate the cache, then delete task outputs (or clean) and rebuild - cacheable tasks should report FROM-CACHE. A plain second build with outputs still present usually reports UP-TO-DATE, which does not prove remote/local cache loading.

---

Adding a New Subproject (Checklist)

1. Choose directory layout consistent with family (grails-foo/… or nested under existing tree).
2. include 'grails-foo' (or nested name) in root settings.gradle.
3. If path != default, set project(':grails-foo').projectDir = file('…').
4. Copy a sibling build.gradle plugin/dependency skeleton; set group/ext.pom* as needed.
5. Wire platform(project(':grails-bom')) or the correct variant BOM.
6. If published: ensure publish plugin + BOM constraint inclusion (base BOM auto-discovers published projects with grails-publish plugins).
7. If it has commands: plan CLI companion artifact (grails-plugin-cli), not runtime leakage.
8. If test-example: use functional-test-config + external coordinates + substitution.
9. Register in any root aggregators if required (docs, publish-root-config, CI matrices).
10. Run:

    ./gradlew :grails-foo:compileGroovy :grails-foo:test :grails-foo:validateDependencyVersions
    

For importing an entire external plugin repository, use mono-repo-integration skill instead of this checklist alone.

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Commands Cheatsheet

# Always from the owning build root (usually repo root)
./gradlew :grails-core:compileGroovy
./gradlew :grails-core:test
./gradlew :grails-core:test --tests 'org.example.SomeSpec'
./gradlew :grails-core:validateDependencyVersions

# Build without tests
./gradlew build -PskipTests

# Style / analysis (see violation-fixer)
./gradlew :grails-core:codeStyle
./gradlew aggregateViolations

# Publish to ~/.m2 (maintainers / forge local cascade) - NOT what end-to-end uses
./gradlew publishAllToMavenLocal   # grails-gradle → root → forge

# Publish to build/local-maven for end-to-end (and forge TestCaseMavenRepo consumers)
(cd grails-gradle && ./gradlew publishAllPublicationsToTestCaseMavenRepoRepository)
./gradlew publishAllPublicationsToTestCaseMavenRepoRepository

# Force re-run tests
./gradlew :module:test --rerun-tasks
# or
DO_NOT_CACHE_TESTS=1 ./gradlew :module:test

# Parallelism override / flake bisect
./gradlew :module:test -PmaxTestParallel=1
./gradlew :module:test -PtestBisect

# Memory
export GRADLE_OPTS='-Xms2G -Xmx5G'

Work in grails-gradle or grails-forge only with that directory's ./gradlew.

Develocity: https://develocity.apache.org - build scans publish when authenticated; remote cache push is CI-only.

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Anti-Patterns (Reject These)

Do not	Do instead
Apply Spring Dependency Management plugin	platform / enforcedPlatform + bom-property-overrides
Apply Spring Dependency Management outside grails-test-examples/spring-dependency-management	Native platforms + bom-property-overrides
Hardcode versions in module dependencies {}	BOM maps in root dependencies.gradle
Introduce libs.versions.toml catalogs	Keep dependencies.gradle maps
Silence validateDependencyVersions without comment	Fix the mismatch (usually bump BOM if transitive is newer; else remove force / align platforms / document override)
Root ./gradlew test after a one-module edit	./gradlew :module:test
Enable configuration cache "because Gradle says so"	Leave off until #15497
Resolve configuration.files in configureEach	Defer to execution / providers
Add an absolute machine path to Test.systemProperties	Use portable task inputs; keep compiler-only base.dir in its @Internal argument provider
Give multiple tasks the same compiler config or report output path	Make every output path task-specific
Use outputs.upToDateWhen in a way that prevents cache loading	Declare inputs and outputs or use a dedicated task
Pack unstable generated files without classpath normalization	Add an explicit normalization ignore when appropriate
Duplicate CompilePlugin settings in module scripts	Trust convention plugins
Invent new plugin IDs without build-logic registration	Add descriptor + tests in build-logic
Bump one wrapper only	Sync all wrapper locations
Put CLI-only deps on runtime classpath	CLI companion artifact / cli* configurations
buildscript { classpath … } for plugins already on pluginManagement

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Gradle 9 Doc Notes (Useful, Not Absolute)

Use official docs for API signatures and deprecations (pin URLs to the version you are bumping toward):

• Gradle 9.6 release notes
• Upgrading major version 9
• Upgrading within Gradle 9.x
• Java Library plugin
• Java Platform / BOM
• Platforms
• Sharing build logic via included builds
• Task configuration avoidance
• Configuration cache (read for compatibility - still off here)
• Version catalogs (docs like them - this repo does not)

Docs say X - we do Y

Gradle docs lean	This repo
Turn on configuration cache	Off (#15497)
Version catalogs (libs.versions.toml)	dependencies.gradle maps + published BOM
enforcedPlatform is dangerous for libraries	Used deliberately for Micronaut-variant BOMs + validator
Prefer toolchains everywhere	options.release from javaVersion=21 via CompilePlugin (toolchains optional elsewhere)
JVM Test Suite plugin for extra suites	Existing test / integrationTest + shared gradle/*-test-config.gradle
Avoid afterEvaluate	Still present in plugins - change carefully; prefer plugins.withId for new code
Configure on demand	Explicitly disabled (Gradle #9489)

Removed/deprecated APIs AI still emits - reject on sight in new code: jcenter(), Project.exec / Project.javaexec (use injected ExecOperations), JavaPluginConvention, ConfigureUtil, old convention APIs, WriteProperties.outputFile (use destinationFile), bare tasks.create / eager getByName when register/named suffice.

Repositories

GrailsRepoSettingsPlugin configures settings-level repos and RepositoriesMode.FAIL_ON_PROJECT_REPOS. Adding repositories { mavenCentral() } inside a random subproject will fail the build. Fix repo needs in settings / the repo settings plugin, not per-module.

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Lessons From Recent 8.0.x Gradle PRs

PR	Takeaway
#15467	Spring DM removed; platforms + bom-property-overrides
#15483	Cacheable tasks need portable inputs; avoid absolute test properties and normalize packed unstable SBOM metadata
#15365	Gradle 9.4 API cleanup; caching annotations; junit launcher
#15532	Overlapping task outputs disable caching; use per-task compiler and report paths
#15537	Bad outputs.upToDateWhen predicates block cache loads; keep GSP output directories distinct
#15672 / #15763	Wrapper multi-location sync discipline
#15730	Prefer Boot BOM inheritance over duplicate pins
#15686 / #15687	code-style / analysis / jacoco / violation aggregation plugins
#15948	CLI split from runtime; companion artifacts
#15963	Groovy compile config script / annotation order
#16006	processResources tokens must be task inputs
#16009	afterEvaluate ordering vs configuration observation
#16076	No compile classpath probes at GroovyCompile configuration time
#16069	Dependency substitution for functional tests is hot-path config work - keep it cheap and cached
#16078	Keep CLI/test-tier deps off the production runtime classpath; do not ship unfixed native tooling (Jansi)

When fixing a new Gradle failure, search merged PR titles for the exception text before inventing a workaround.

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Agent Quality Bar

Strong 8.0.x Gradle PRs are small, sibling-consistent, and evidence-backed:

• State the Problem, Fix, Why, and Verification in the PR or handoff.
• Match the closest existing module, script, or convention plugin before adding a new pattern.
• Avoid drive-by reformatting, dependency churn, or unrelated modernization.
• Verify with the narrowest commands that cover the changed project: compile, targeted tests, and dependency validation as applicable.
• For grails-gradle, include the relevant TestKit coverage.
• Use dual review when available, especially for build, dependency, and publishing changes.
• Report exact commands and results. Evidence beats confidence.

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Files to Read First (By Task)

Task	Read
New library module	Sibling build.gradle, settings.gradle include section, CompilePlugin.groovy
Version bump	dependencies.gradle, maybe Spring Boot BOM notes in PR #15730
Wrapper bump	gradle/wrapper/gradle-wrapper.properties comment checklist
Test wiring	gradle/test-config.gradle, gradle/functional-test-config.gradle
BOM / platform	grails-bom/base/build.gradle, GrailsDependencyValidatorPlugin.groovy
App plugin behavior	grails-gradle/plugins/.../GrailsGradlePlugin.groovy
Convention plugin change	build-logic/plugins/... + its Spock tests
Publishing	PublishPlugin.groovy, gradle/publish-root-config.gradle
Style gates	violation-fixer skill + code-style plugins

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Definition of Done (Gradle Change)

• Matches sibling module patterns (plugins, group, platform, apply scripts)
• No hardcoded versions that belong in dependencies.gradle
• validateDependencyVersions clean for touched modules (or documented override)
• Scoped Gradle verify command green (:module:compileGroovy, :module:test, plugin TestKit as applicable)
• Wrapper/version sync complete if Gradle version changed
• No configuration-time resolution / nested afterEvaluate hazards introduced
• No absolute machine paths in Test.systemProperties; compiler base.dir remains isolated in BaseDirArgumentProvider
• No overlapping task outputs; classpath normalization considered for packed generated files
• Apache headers on new files
• User-facing behavior documented if it affects app builds (grails-doc)
• For commit-ready work, use violation-fixer to run the AGENTS.md gate: ./gradlew clean aggregateViolations :grails-test-report:check --continue. This is not required merely to read this skill.

If you only remember three things: copy siblings, BOM owns versions, never resolve configurations while configuring tasks.