TYPO3 Core

This issue works as an umbrella to list all things to consider (soft factors and hard requirements) if TYPO3 Core should only support Composer-based installations.

From a hard-requirement perspective

1. Migration from non-composer based installations to composer-mode installations.

What about PackageStates.php?
What about ext_emconf.php?
What about modified extensions?
How to differentiate between "TER" extensions (= updateable) and "local" / "per-project" extensions?
What about extensions with wrong "dependencies"

2. Web-Installer setting up TYPO3 in Composer Mode

We don't want to loose the functionality to install TYPO3 via a Web GUI.

3. Web-Management Interface to install / remove extensions

Somehow we want to have editors still using the Extension Manager (or whatever we want to name this) where people can search for extensions and install them.

• Have a best practice set up for newcomers on how to work with local extensions (path repositories)
• Make the GUI more intuitive than it is now (composer output on CLI might be tricky already)
• What if a production system does not ship their composer.json/composer.lock during deployment?
• What about the current "Auto-Update" feature in the Install Tool?