Context

Currently, @internal annotations in Psalm work well for classes, methods, and properties, but the same behavior does not seem to apply to traits.

According to the docs, traits should also be supported, but in practice Psalm does not report any issue when a trait marked as @internal is used from another namespace.

Example

https://psalm.dev/r/937049bbb3

<?php declare(strict_types=1);

namespace A\B {
    /**
     * @internal
     * @psalm-internal A\B
     */
    trait InternalTrait {
        public function t(): void {}
    }

    /**
     * @internal
     * @psalm-internal A\B
     */
    class InternalClass {
        public function c(): void {}
    }
}

namespace A\C {
    class UsesTrait {
        use \A\B\InternalTrait; // ← expected internal-visibility error (cross-namespace use)
    }

    class UsesClass extends \A\B\InternalClass { // ← Psalm reports an internal-visibility error here
        public function demo(): void {}
    }
}

Expected behavior

I would expect Psalm to raise an error similar to how it does with internal classes:

ERROR: InternalTrait - A\C\UsesTrait uses internal trait A\B\InternalTrait from A\B

Actual behavior

No issue is reported, even though the trait is annotated with @internal and is being used outside of its declaring namespace.

Why this matters

• Traits are a common way to share code internally in frameworks (e.g. Laravel).
• Being able to mark them as @internal is important for package authors who want to expose only certain APIs while keeping others private.
• This would align trait behavior with class/method @internal enforcement.

Suggested solutions / questions

• Is this a missing feature in Psalm’s internal visibility checks?
• Should trait usage be treated the same way as class inheritance when resolving @internal?
• Would maintainers accept a PR to add this behavior?

Thanks for considering!

Would you like me to frame it as a bug report (“this doesn’t work, even though docs imply it should”) or as a feature request (“it would be nice if traits supported @internal like classes”)?