add release note for Composer 2.8.3

source/releasenotes/2024-12-10-composer-2-8-3.md

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+---
+title: Composer 2.8.3 now available
+published_date: "2025-01-16"
+categories: [infrastructure,tools-apis]
+---
+
+Composer 2.8.3 is now used in both runtime environments and integrated composer build environments on Pantheon.
+
+### Automatic rollout - No action required
+
+Composer 2.8.3 will gradually roll out to automatically. No action required from you during this process.
+
+### Breaking changes
+
+Developers should be aware of a potentially breaking change introduced in [2.8.0](https://github.com/composer/composer/releases/tag/2.8.0). The fallback behavior from `https_proxy` to `http_proxy` has been removed, as previously warned in [2.7.3](https://github.com/composer/composer/releases/tag/2.7.3). If your configurations depend on this behavior, update them to avoid connectivity issues.
+
+### Highlights
+
+Composer 2.8.3 introduces a range of improvements and updates made between versions 2.7.7 and 2.8.3, including:
+
+* **`--patch-only` flag for updates**: Restrict updates to patch versions with this new flag for the `update` command.
+* **Improved interactive package updates**: Enhanced package display makes interactive updates more intuitive.
+* **JSON schema validation**: New validation ensures integrity for `composer.lock` files.
+* **PHP 8.4 compatibility**: Compatibility updates for the latest PHP version.
+* **Bug fixes**: Resolved issues with provider suggestions and lock file schemas.
+
+View an overview of the changes made between [2.7.7 and 2.8.3 by comparing the tags](https://github.com/composer/composer/compare/2.7.7...2.8.3) or explore the highlights on [Composer's Releases page](https://github.com/composer/composer/releases).
+
+### Notes
+
+Composer commands can be run against sites on Pantheon via the [Terminus Composer plugin](https://github.com/pantheon-systems/terminus-composer-plugin). For operations that modify version controlled code (like adding a module via `composer require` which will change `composer.json` and `composer.lock`) you must run such commands in Dev or Multidev environments where version controlled files are writable. Such files are not writeable in Test and Live environments.
+To learn more about Composer on Pantheon, visit our guide on [Integrated Composer](https://docs.pantheon.io/guides/integrated-composer).