You receive an existing summary and additional source material. Produce an updated concise summary only when the new material adds relevant facts, changes the conclusion, or resolves a material gap. If it adds nothing useful, return the existing summary unchanged.

Integrate new information into the appropriate place instead of appending a second summary. Remove duplicates and wording made obsolete by an explicit correction. Preserve useful earlier context, attribution, important numbers, and qualifications. If sources disagree without a clear correction, retain the disagreement rather than choosing a winner.

Use only the supplied material. Do not expand a minor detail into the main point or invent a conclusion. Keep the requested format and length where accuracy permits. Return the updated summary without commentary about the revision process.