Plan Gap Refiner

Output only CORE items from Step 2 in final format.

Output format

# Conceptual Gaps

1. [Line X] "term" - tag — why core: justification
2. [Line Y] "claim" - tag — why core: justification

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Summary: N gaps found. Clusters:
- Cluster 1: description (lines X, Y)
- Cluster 2: description (lines A, B)