Remove entity button not showing in Complex Inline Entity Form after upgrading to 3.x from 1.x

Claude Code says:

What it fixes — a real bug

At InlineEntityFormComplex.php:329, $have_multiple_existing_entities gates whether the "Remove" button is shown on a required reference field when !allow_new && allow_existing (line 491). The current code:

  $have_multiple_existing_entities = count($handler->getReferenceableEntities(NULL, 'CONTAINS', 2)) > 1;

SelectionInterface::getReferenceableEntities() returns entities grouped by bundle:
['bundle_a' => [id1 => label, id2 => label], 'bundle_b' => [id3 => label]]

count() on that array counts bundles that have at least one match, not entities. So 2 entities in the same bundle = count = 1 → reports "not multiple" even though there are two candidates. The required field incorrectly hides its Remove button, blocking the user from swapping the reference.

The patch's logic — "more than one bundle, OR exactly one bundle with more than one entity inside it" — is correct for all cases (0, 1, 2-same-bundle, 2-cross-bundle) and plays nicely with the limit=2 query cap.

Concerns

1. array_shift() on a local is noisy. It mutates the array (fine, it's a local copy) but also pays an O(n) reindex cost for a value you discard. reset() is the idiomatic one-liner:

  $reference_items = $handler->getReferenceableEntities(NULL, 'CONTAINS', 2);
  $have_multiple_existing_entities = count($reference_items) > 1
    || (count($reference_items) === 1 && count(reset($reference_items)) > 1);

Or the clearer-intent version:

  $reference_items = $handler->getReferenceableEntities(NULL, 'CONTAINS', 2);
  $total = array_sum(array_map('count', $reference_items));
  $have_multiple_existing_entities = $total > 1;

Either is shorter than the if/elseif/else chain and preserves the limit=2 early-out. The array_sum(array_map('count', ...)) form also avoids making the reader think about bundle grouping at the call site.

2. No comment explaining the grouped-by-bundle shape. A one-line comment above the assignment saves the next reader a trip to the Selection API docs:

  // getReferenceableEntities() returns matches grouped by bundle, so a
  // single-bundle return with 2 entries still counts as "multiple".

3. No regression test. The fix should ship with a test — required reference field with allow_new = FALSE, allow_existing = TRUE, single target bundle, two candidate entities; assert Remove button is present. The inverse case (one candidate → button hidden) would also lock in current behavior. Fits in tests/src/FunctionalJavascript/ComplexWidgetTest.php.

4. Commit message not shown here. Assuming the d.o issue is known, the commit message should name it and state the bug in one line (current behavior only counts bundles, not entities).

Verdict

Correct fix for a genuine bug, and the patch passes all the edge cases I can think of. Needs small polish (reset over array_shift, ideally collapsed to a single expression), a short comment, and a regression test before merge.