Manual:Composer.json best practices

When creating a composer.json file for your extension/library/etc that will be used inside MediaWiki, here are a few best practices to follow.

You should also run [https://getcomposer.org/doc/03-cli.md#validate composer validate], which will point out schema errors.

Configuration
Composer's autoloader is slower than MediaWiki's, and most of the classes being loaded are likely to be found inside MediaWiki, so append the composer autoloader instead of prepending it. See [https://github.com/wmde/WikidataBuilder/pull/32 this] for some more details.
 * "prepend-autoloader": false.
 * "optimize-autoloader": true.

No reason not to optimize.

Good example: [https://github.com/wikimedia/mediawiki/blob/master/composer.json mediawiki/core]

Dependencies

 * Dependencies should be pinned to a specific version number or sha1 commit if a tag isn't available.


 * For development tools like phpunit or phpcs, "dev-master" or "*" is acceptable.

Good example: [https://github.com/wikimedia/mediawiki/blob/master/composer.json mediawiki/core]

Naming
Libraries hosted in Gerrit or by the Wikimedia GitHub account should typically be published under the [https://packagist.org/packages/wikimedia/ "wikimedia" namespace] (e.g. "wikimedia/cdb", "wikimedia/simplei18n").

The use of the [https://packagist.org/packages/mediawiki/ "mediawiki" namespace] should be reserved for extensions and other intrinsically MediaWiki related components (bot frameworks, etc).

Projects hosted at GitHub under an independent organization are encouraged to adopt a similar convention of an organization namespace to be applied consistently across the libraries published by the group.

Authors
Major authors to the project should be documented in the [https://getcomposer.org/doc/04-schema.md#authors "authors"] property.

At least the name and email fields should be filled out.

For libraries, this will be displayed on Special:Version in the "Installed libraries" section.

Extensions
Extension names should be all lowercase with hyphens as word separators. For example:


 * Extension:WikiEditor → mediawiki/wiki-editor


 * Extension:MassMessage → mediawiki/mass-message

To make themselves installable, a dependency upon "composer/installers" with version >= 1.0.1 is required, and the type needs to be set to "mediawiki-extension".

Good example: [https://github.com/cmln/mw-bootstrap/blob/master/composer.json mediawiki/extensions/Bootstrap]

Skins
Mainly the same as extensions, except the type should be "mediawiki-skin".

The names should end with a suffix of "-skin".

Because composer uses lowercase names for packages (e.g. <tvar|vector> </>), the <tvar|name> </> property must be set to the uppercase name (e.g. <tvar|Vector> </>) so it is cloned in the right directory.

To make themselves installable, a dependency upon "composer/installers" with version >= 1.0.13 is required, and the type needs to be set to "mediawiki-skin".

Good example: [<tvar|url>https://github.com/wikimedia/mediawiki-skins-Vector/blob/master/composer.json</> mediawiki/skins/Vector]

Also extension.json
Extensions and skins register information about themselves using an  or   file. Some metadata fields in these files overlap (discussed in T89456), including
 * and
 * and