Overriding Third-Party Resource Configs 

How it works 

At boot time the loader runs two passes over every active package:

1. Base pass — loads every Configuration/TcaApi/*.php file and writes the result into $GLOBALS['TCA_API'] keyed by resourceName. When two packages define the same resourceName, the last package to load wins (TYPO3 package load order).
2. Override pass — requires every Configuration/TcaApi/Overrides/*.php file (depth 0, sorted alphabetically within each package). Override files are plain PHP side-effects on $GLOBALS['TCA_API'] — no return value is expected.

After both passes the global is parsed into typed ApiDefinition DTOs and cached. At runtime, use ApiRegistry::get() to read definitions; the global itself is not guaranteed to be set on cache hits.

Writing an override file 

Create a PHP file under Configuration/TcaApi/Overrides/ in any active extension. The filename is arbitrary.

Add a column

<?php

declare(strict_types=1);

// EXT:my_ext/Configuration/TcaApi/Overrides/ExtendArticles.php
$GLOBALS['TCA_API']['articles']['columns']['subtitle'] = [
    'groups' => ['list', 'show'],
];

Remove a column

unset($GLOBALS['TCA_API']['articles']['columns']['internal_notes']);

Restrict operations

$GLOBALS['TCA_API']['articles']['general']['operations'] = ['list', 'show'];

Change a security role

use MaikSchneider\TcaApi\Enum\AccessRole;

$GLOBALS['TCA_API']['articles']['security']['delete'] = AccessRole::FE_USER;

Add a filter

use MaikSchneider\TcaApi\Filter\ExactFilter;

$GLOBALS['TCA_API']['articles']['filters']['category_id'] = ExactFilter::class;

Multiple overrides for the same resource are applied in alphabetical filename order within a package, and in TYPO3 package load order across packages. The last write always wins.

Explicit vs. implicit mode 

The visibility mode — implicit (all TCA columns exposed) vs. explicit (only columns with groups) — is re-evaluated after all overrides are applied.

• Adding a column with a groups key to an otherwise implicit resource switches it to explicit mode for that resource.
• Removing the only column that had groups switches it back to implicit.
• Adding a column without groups to an explicit resource keeps it explicit; the new column is recorded in the DTO but excluded from all operation outputs.