[QTI] An invalid question with several interactions publishes without an Incomplete indicator #6289

❌ This issue is not open for contribution. Visit Contributing guidelines to learn about the contributing process and how to find suitable issues.

Target branch: unstable

Observed behavior

validateQtiItem returns no errors for an item with several interactions when one of them is invalid. Such an item is unsupported (#6105), so its interactions are never validated.

• The card shows no Incomplete indicator.
• The exercise counts as complete and publishes.

Errors and logs

None.

Expected behavior

An unsupported item that is invalid blocks publishing, as AlexVelezLl ruled on #6105: "if the item is unsupported because of a parse error or invalid, uneditable qti item, then it should be publish-blocking". Only valid unsupported items are publishable.

User-facing consequences

Learners get a question that can't be answered correctly, e.g. a choice with no correct response in a scored exercise. Authors aren't warned and can't fix it in Studio.

Steps to reproduce

1. Take MULTI_INTERACTION_ITEM_DOCUMENT (QTIEditor/utils/testingFixtures.js) and remove the second interaction's <qti-correct-response>.
2. Call validateQtiItem(xml, { allowFreeResponse: false }): it returns [].
3. Put the item in an exercise: no Incomplete indicator, and the exercise publishes.

Context

• validateItem.js: the !isSupportedItem(...) branch returns only descriptor errors and skips each interaction's validation and the free-response check.
• [QTI] Show items whose body the editor can't reproduce as unsupported #6225 makes items with content beside their interaction unsupported, so the same skip will apply to them.
• [QTI] Prompt authors to delete questions the editor cannot open and publishing rejects #6217 adds the delete prompt for publish-blocking unsupported items. This issue decides which items are publish-blocking.
• Found while reviewing [QTI] Show items whose body the editor can't reproduce as unsupported #6225. Reproduced on upstream/unstable.

AI usage

I used Claude Code to review the #6225 branch. It found this and reproduced it on upstream/unstable by calling validateQtiItem from a scratch Jest test.