[Question]: Is there a function for overlapping and connecting blocks?

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### Describe your problem

Can't we set overlap before segmenting? Currently, after deepdoc segmentation, all paragraphs are independent. If the segmentation effect is not ideal, two paragraphs in the same chapter will be segmented into two blocks. However, when searching, these two paragraphs need to be found to maintain integrity. If there is no overlap, the other paragraph may not be retrieved.
Similar to this function in the dify knowledge base

Start by reviewing the deepdoc segmentation and retrieval flow to understand how paragraphs become independent blocks. The issue does not name files, tests, or a specific overlap behavior; done would require an agreed design for configuring overlap or connecting related blocks, plus validation that both paragraphs remain retrievable.

Written by the indexing model from the issue text.