feat(cfn-property-mixins): graduate to stable @aws-cdk/cfn-property-mixins package

[mrgrain]

Reason for this change

The CFN property mixins feature has been incubating in @aws-cdk/mixins-preview and is now stable enough to graduate to its own dedicated package. The preview package name signals instability and carries unrelated experimental features, which is no longer appropriate for a feature ready for general consumption. A stable, focused package gives users a clear import path and a name that reflects the feature's maturity.

Description of changes

This introduces @aws-cdk/cfn-property-mixins as the stable home for auto-generated CloudFormation property mixins. The package provides a CfnXxxPropsMixin class for every CloudFormation resource, organized into per-service submodules that mirror the aws-cdk-lib module structure (e.g. @aws-cdk/cfn-property-mixins/aws-s3). The code generation reuses the same cfnPropMixins.generateAll() pipeline from @aws-cdk/spec2cdk that already powers @aws-cdk/mixins-preview, with its own gen.ts orchestration and package base names.

The generated mixin classes now import IMergeStrategy and PropertyMergeStrategy from aws-cdk-lib/core (where they were moved in a prior commit) rather than from the preview package's internal helpers. This is reflected in small updates to the spec2cdk builder and helpers.

The awslint exclusion list and pkglint visibility rules are updated to include the new package. Unit tests for S3 property mixins cover property application, merge strategies, construct type matching, and cross-service references.

Describe any new or updated permissions being added

None.

Description of how you validated changes

Unit tests verify property application, deep merge and override strategies, construct type matching, and cross-service KMS key references. The code generation pipeline produces submodules for all CloudFormation services.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[aws-cdk-automation]

➡️ PR build request submitted to test-main-pipeline ⬅️

A maintainer must now check the pipeline and add the pr-linter/cli-integ-tested label once the pipeline succeeds.

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-03-11 08:25 UTC · Rule: default-squash
• ✅ Checks passed · in-place
• ✅ Merged — 2026-03-11 09:09 UTC · at 064f0052f99186c1424e87f1437665f6fe60a3e8

This pull request spent 43 minutes 42 seconds in the queue, including 43 minutes 31 seconds running CI.

Required conditions to merge

• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • feat(cfn-property-mixins): graduate to stable @aws-cdk/cfn-property-mixins package #37215
• #changes-requested-reviews-by = 0 [🛡 GitHub branch protection]
  • feat(cfn-property-mixins): graduate to stable @aws-cdk/cfn-property-mixins package #37215
• any of [🛡 GitHub branch protection]:
  • check-success = validate-pr
  • check-neutral = validate-pr
  • check-skipped = validate-pr
• any of [🛡 GitHub branch protection]:
  • check-success = build
  • check-neutral = build
  • check-skipped = build

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

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