Issue

[#7107] Core Index Mismatch in Commitments and Descriptor

Description

This PR resolves a bug where normal (non-malus) undying collators failed to generate and submit collations, resulting in the following error:

ERROR tokio-runtime-worker parachain::collation-generation: Failed to construct and distribute collation: V2 core index check failed: The core index in commitments doesn't match the one in descriptor.

More details about the issue and reproduction steps are described in the related issue.

Summary of Fix

• Core index is now derived from commitments (via UMP signals) instead of sequential claim queue indexes;
• The fix ensures functionality remains unchanged for parachains not using UMP signals;
• Added checks to stop processing if multiple cores are assigned but the same core is selected repeatedly.

TODO

• Implement the fix;
• Add tests;
• Add PRdoc.