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docs(text-splitters): troubleshooting when chunk_overlap seems not to apply #33462

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docs(text-splitters): troubleshooting when chunk_overlap seems not to apply #33462

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11 changes: 11 additions & 0 deletions libs/text-splitters/README.md
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Expand Up @@ -21,6 +21,17 @@ LangChain Text Splitters contains utilities for splitting into chunks a wide var

For full documentation, see the [API reference](https://reference.langchain.com/python/langchain).

## 🛠️ Troubleshooting: `chunk_overlap` seems not to apply

- After header based splitting (e.g., `MarkdownHeaderTextSplitter`), use **`split_documents(docs)`** (not `split_text`) so overlap is applied **within each section** and per section metadata (headers) is preserved on chunks.
- Overlap appears only when a **single input section** exceeds `chunk_size` and is split into multiple chunks.
- Overlap **does not cross** section/document boundaries (e.g., `# H1` → `## H2`).
- If the header becomes a tiny first chunk, there's nothing meaningful to overlap. Consider `strip_headers=True` in `MarkdownHeaderTextSplitter`, or reduce separators so the section forms a longer segment.
- If your text lacks newlines/spaces, keep a fallback `""` in `separators` so the splitter can still split and apply overlap.

> Looking for examples and API details? See the [Text Splitters how-to](https://python.langchain.com/docs/how_to/#text-splitters) and the [API reference](https://python.langchain.com/api_reference/text_splitters/index.html).


## 📕 Releases & Versioning

See our [Releases](https://docs.langchain.com/oss/python/release-policy) and [Versioning](https://docs.langchain.com/oss/python/versioning) policies.
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