The first release candidate for the upcoming 1.0.0 GA. Public API is frozen since v0.5.0 and now hardened with field-level diagnostics, modernized Javadoc, comprehensive null-safety annotations, and a stress/chaos testing framework. Deprecated APIs from the 0.5.0 line have been removed.

• ✅ API Hardening - Public API surface frozen since 0.5.0; deprecated wrappers from the 0.5.0 line removed
• ✅ Field-Level Diagnostics - New FieldOperation / FieldAwareRule model surfaces per-field metadata in MigrationReport
• ✅ Modernized Javadoc - Comprehensive Javadoc overhaul across every module for 1.0.0 readiness
• ✅ Pervasive Null-Safety - @NotNull / @Nullable annotations applied across the public API and internals
• ✅ JMH Benchmark Suite - New aether-datafixers-benchmarks module with reproducible performance benchmarks
• ✅ Stress & Chaos Testing - High-concurrency, sustained-load, memory-pressure, and chaos injection ITs
• ✅ Migration Guide - Detailed v0.5.x → 1.0.0 migration documentation including automated patterns
• ✅ Operational Runbook - Production troubleshooting guide and operational documentation
• ✅ Aether Style Guard - CI-enforced style guard ensures consistent code style across all modules
• ✅ DCO & Contributor Recognition - Developer Certificate of Origin and CONTRIBUTORS.md added
• ✅ Bug Fix Sweep - 100+ issues addressed across API, codec, core, CLI, testkit, schema-tools, and Spring Boot starter

<dependency>
  <groupId>de.splatgames.aether.datafixers</groupId>
  <artifactId>aether-datafixers-core</artifactId>
  <version>1.0.0-rc.1</version>
</dependency>

Using the BOM

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>de.splatgames.aether.datafixers</groupId>
      <artifactId>aether-datafixers-bom</artifactId>
      <version>1.0.0-rc.1</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <!-- No version needed -->
  <dependency>
    <groupId>de.splatgames.aether.datafixers</groupId>
    <artifactId>aether-datafixers-core</artifactId>
  </dependency>
</dependencies>

dependencies {
  implementation 'de.splatgames.aether.datafixers:aether-datafixers-core:1.0.0-rc.1'
  // Or with BOM:
  implementation platform('de.splatgames.aether.datafixers:aether-datafixers-bom:1.0.0-rc.1')
  implementation 'de.splatgames.aether.datafixers:aether-datafixers-core'
}

dependencies {
  implementation("de.splatgames.aether.datafixers:aether-datafixers-core:1.0.0-rc.1")
  // Or with BOM:
  implementation(platform("de.splatgames.aether.datafixers:aether-datafixers-bom:1.0.0-rc.1"))
  implementation("de.splatgames.aether.datafixers:aether-datafixers-core")
}

TypeRewriteRule instances now carry structured FieldOperation metadata, enabling field-aware diagnostics throughout the migration pipeline.

MigrationReport report = fixer.update(typeRef, dynamic, fromVersion, toVersion);

for (FixExecution exec : report.executions()) {
    for (FieldOperation op : exec.fieldOperations()) {
        System.out.printf("%s on field '%s' (type %s)%n",
            op.type(),      // FieldOperationType: RENAME, ADD, REMOVE, TRANSFORM, ...
            op.fieldName(),
            op.typeReference());
    }
}

Features:

• FieldAwareRule marker interface implemented by all field operations and compositions in Rules
• Field operations bubble up through seq, seqAll, choice, batch, topDown, bottomUp
• CLI exposes field-level details via the --diagnostics flag (aether-datafixers-cli)
• Spring Boot Actuator /actuator/datafixers endpoint reports field operations per execution
• Static field-level coverage analysis available via MigrationAnalyzer

Every public type in every module received a Javadoc pass focused on the 1.0.0 audience:

• Consistent voice and structure across modules
• Explicit thread-safety contracts on every public type
• Behavioral guarantees, ordering invariants, and failure modes documented
• {@inheritDoc} with explicit @param / @return to satisfy the Aether Style Guard
• Cross-references ({@link}) between related types repaired and expanded

@NotNull and @Nullable annotations now cover the public API and internals, providing static null-safety guarantees for callers using nullability-aware tooling (IntelliJ, Checker Framework, NullAway).

// API contracts are now explicit at compile time
@NotNull DataResult<Typed<T>> apply(@NotNull Typed<T> input,
                                    @Nullable DiagnosticContext context);

The new aether-datafixers-benchmarks module provides reproducible JMH benchmarks for the core migration paths:

# Build the shaded benchmark JAR and run the suite
./run-benchmarks.sh

Initial baselines are committed under benchmark-results/ for regression comparisons.

New stress / chaos integration tests under aether-datafixers-functional-tests:

Run with:

mvn verify -Pstress -pl aether-datafixers-functional-tests
mvn verify -Pit    -pl aether-datafixers-functional-tests -Dgroups=chaos

Code style is now enforced in CI via the Aether Style Guard. The opt-in styleguard profile is wired up on every module and validated by .github/workflows/ci-pr.yml and ci-push.yml.

• v0.5.x → 1.0.0 Migration Guide — step-by-step migration patterns, breaking changes, and troubleshooting (docs/migration/)
• Operational Runbook — production debugging, error scenarios, monitoring, and recovery procedures (docs/operations/)
• Troubleshooting Guide — common errors and debugging tips (docs/troubleshooting/)

• DCO file added; PRs now sign off under the Developer Certificate of Origin
• CONTRIBUTORS.md recognizes every contributor to the project

The deprecated wrappers announced in v0.5.0 have been removed in 1.0.0:

See docs/migration/v0.5-to-v1.0.md for the full migration guide.

New in 1.0.0-rc.1

• Introduced field-level diagnostics: FieldOperation, FieldOperationType, and FieldAwareRule propagated through every combinator in Rules
• Static field-level coverage analysis added to MigrationAnalyzer
• CLI --field-diagnostics flag and Spring Boot Actuator endpoint surface field-level details
• New aether-datafixers-benchmarks module with JMH benchmark suite and baseline results
• Stress and chaos integration tests: HighConcurrencyMigrationStressIT, SustainedLoadMigrationStressIT, MixedRegistryAccessStressIT, MemoryPressureStressIT, RandomDelaysChaosIT, RandomFailuresChaosIT
• Comprehensive Javadoc modernization across all modules
• Pervasive @NotNull / @Nullable annotations across the public API and internals
• Aether Style Guard integrated into PR and push CI workflows
• Migration guide (v0.5.x → 1.0.0), benchmark guide, and operational runbook added
• Developer Certificate of Origin (DCO) and CONTRIBUTORS.md introduced
• MigrationResult now implements equals / hashCode
• Finder.index() validates non-negative indices at construction
• Typed.encodeAndGet now returns DataResult with structured error reporting
• 100+ targeted bug fixes across API, codec, core, CLI, testkit, schema-tools, and the Spring Boot starter
• Hardened devcontainer for Java / Python / Claude Code sandboxing

Removed (previously deprecated in 0.5.0)

• de.splatgames.aether.datafixers.codec.gson.GsonOps wrapper
• de.splatgames.aether.datafixers.codec.jackson.JacksonOps wrapper
• TestData.jackson() factory method

Full Changelog: v0.5.0...v1.0.0-rc.1

Only the three deprecated wrappers from 0.5.0 are removed (see table above). All other public API is source-compatible with v0.5.0.

1. Update Maven / Gradle coordinates to 1.0.0-rc.1
2. Replace any remaining imports of the removed wrappers with their replacements
3. Re-run mvn verify against your project; the compiler will catch every removed reference
4. Optional: opt into field-level diagnostics by inspecting FixExecution#fieldOperations on MigrationReport

Detailed walkthrough in docs/migration/v0.5-to-v1.0.md.

Please file RC feedback as GitHub issues against the aether-datafixers repository. Any blocker reported during the RC window will be considered for inclusion in the 1.0.0 GA.

• Promote 1.0.0-rc.1 to 1.0.0 after the RC feedback window
• Final documentation polish and tutorial coverage
• Semantic-versioning guarantees activated for the 1.0.x line

• Extended cookbook and video tutorials
• Additional codec integrations driven by community demand

MIT - see LICENSE.