chore: import upstream snapshot with attribution

docs-website/reference/experiments-api/experimental_preprocessors_api.md

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+---
+title: "Preprocessors"
+id: experimental-preprocessors-api
+description: "Pipelines wrapped as components."
+slug: "/experimental-preprocessors-api"
+---
+
+<a id="haystack_experimental.components.preprocessors.md_header_level_inferrer"></a>
+
+## Module haystack\_experimental.components.preprocessors.md\_header\_level\_inferrer
+
+<a id="haystack_experimental.components.preprocessors.md_header_level_inferrer.MarkdownHeaderLevelInferrer"></a>
+
+### MarkdownHeaderLevelInferrer
+
+Infers and rewrites header levels in Markdown text to normalize hierarchy.
+
+    First header → Always becomes level 1 (#)
+    Subsequent headers → Level increases if no content between headers, stays same if content exists
+    Maximum level → Capped at 6 (######)
+
+    ### Usage example
+    ```python
+    from haystack import Document
+    from haystack_experimental.components.preprocessors import MarkdownHeaderLevelInferrer
+
+    # Create a document with uniform header levels
+    text = "## Title
+## Subheader
+Section
+## Subheader
+More Content"
+    doc = Document(content=text)
+
+    # Initialize the inferrer and process the document
+    inferrer = MarkdownHeaderLevelInferrer()
+    result = inferrer.run([doc])
+
+    # The headers are now normalized with proper hierarchy
+    print(result["documents"][0].content)
+    > # Title
+## Subheader
+Section
+## Subheader
+More Content
+    ```
+
+<a id="haystack_experimental.components.preprocessors.md_header_level_inferrer.MarkdownHeaderLevelInferrer.__init__"></a>
+
+#### MarkdownHeaderLevelInferrer.\_\_init\_\_
+
+```python
+def __init__()
+```
+
+Initializes the MarkdownHeaderLevelInferrer.
+
+<a id="haystack_experimental.components.preprocessors.md_header_level_inferrer.MarkdownHeaderLevelInferrer.run"></a>
+
+#### MarkdownHeaderLevelInferrer.run
+
+```python
+@component.output_types(documents=list[Document])
+def run(documents: list[Document]) -> dict
+```
+
+Infers and rewrites the header levels in the content for documents that use uniform header levels.
+
+**Arguments**:
+
+- `documents`: list of Document objects to process.
+
+**Returns**:
+
+dict: a dictionary with the key 'documents' containing the processed Document objects.
+