feat: s3 and ecs service mixins are now available in aws-cdk-lib

[mrgrain]

Reason for this change

The S3 and ECS mixins were previously only available in the @aws-cdk/mixins-preview experimental package. Now that the core Mixins mechanism (Mixin, IMixin, MixinApplicator, ConstructSelector) has landed in constructs and aws-cdk-lib, the service-specific mixins should live alongside their respective service modules in aws-cdk-lib. This makes them discoverable, properly versioned, and available without an additional dependency.

The mixins-preview package retains only the Logs Delivery Mixins and EventBridge Event Facades that haven't been promoted yet.

Description of changes

Three S3 mixins (BucketVersioning, BucketBlockPublicAccess, BucketPolicyStatements) and one ECS mixin (ClusterSettings) are added to aws-cdk-lib under new lib/mixins/ subdirectories in their respective service modules. Each mixin is exposed through a mixins namespace export (e.g. s3.mixins.BucketVersioning), following a convention enforced by a new pkglint rule that requires any submodule with a lib/mixins/ directory to re-export it.

A new awslint rule set ensures all IMixin implementors extend the Mixin base class, live in a lib/mixins/ directory on disk, and belong to a .mixins. jsii submodule namespace. The spec2cdk codegen is updated to automatically generate .jsiirc.json target mappings for any lib/mixins/ directory it encounters, so future service mixins get correct Java, .NET, Python, and Go package names without manual setup.

The corresponding implementations and tests are removed from mixins-preview, and its README is updated to point users to aws-cdk-lib.

Describe any new or updated permissions being added

None.

Description of how you validated changes

Unit tests are included for all S3 and ECS mixins. An integration test for the ECS ClusterSettings mixin is included.

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]

(This review is outdated)

[github-actions]

⚠️ Experimental Feature: This security report is currently in experimental phase. Results may include false positives and the rules are being actively refined.
Please try merge from main to avoid findings unrelated to the PR.

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[github-actions]

⚠️ Experimental Feature: This security report is currently in experimental phase. Results may include false positives and the rules are being actively refined.
Please try merge from main to avoid findings unrelated to the PR.

---

	Tests	Passed ❌️	Skipped	Failed
Security Guardian Results with resolved templates

Test	Result
No test annotations available

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✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[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

Rule: default-squash

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• ✅ Entered queue — 2026-03-04 14:37 UTC
• ✅ Checks passed · in-place
• ✅ Merged — 2026-03-04 15:51 UTC · at 5a24ed389a0a9a7b61e333e46e0a1d5f018e3554

This pull request spent 1 hour 14 minutes 23 seconds in the queue, including 44 minutes 2 seconds running CI.

Required conditions to merge

• #approved-reviews-by >= 1 [🛡 GitHub branch protection]
  • feat: s3 and ecs service mixins are now available in aws-cdk-lib #37151
• #changes-requested-reviews-by = 0 [🛡 GitHub branch protection]
  • feat: s3 and ecs service mixins are now available in aws-cdk-lib #37151
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  • check-neutral = validate-pr
  • check-skipped = validate-pr
• any of [🛡 GitHub branch protection]:
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  • check-neutral = build
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[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]

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).

[github-actions]

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