rumdl 0.2.63

A fast Markdown linter and formatter written in Rust
Documentation 
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---
description: "Lint MkDocs and Material for MkDocs Markdown without false positives on admonitions, tabs, snippets, or extension syntax."
---

# Lint MkDocs Markdown with rumdl

Use rumdl's `mkdocs` flavor to lint MkDocs and Material for MkDocs projects
without treating valid admonitions, content tabs, snippets, mkdocstrings blocks,
or common extension syntax as ordinary Markdown errors. The flavor changes how
relevant rules interpret MkDocs constructs; it does not disable linting for the
rest of the document.

```toml title=".rumdl.toml"
[global]
flavor = "mkdocs"
```

Then run a read-only check:

```bash
rumdl check docs/
```

## Supported Patterns

### Auto-References

MkDocs autorefs plugin allows shorthand links to documented objects:

```markdown
See [ClassName][] for details.
Use [module.function][] in your code.
```

**Affected rules**: MD042 (empty links), MD052 (reference links)

### Admonitions

MkDocs admonition syntax is recognized:

```markdown
!!! note "Title"
    Content inside admonition.

!!! warning
    Warning content.

??? tip "Collapsible"
    Hidden content.
```

**Affected rules**: MD031 (blanks around fences), MD046 (code block style)

### Content Tabs

Material for MkDocs tab syntax:

```markdown
=== "Tab 1"
    Content for tab 1.

=== "Tab 2"
    Content for tab 2.
```

**Affected rules**: MD046 (code block style)

### Snippets

MkDocs snippets for including external files:

```markdown
--8<-- "path/to/file.md"
;--8<--
```

**Affected rules**: MD024 (duplicate headings), MD052 (reference links)

### HTML with Markdown Attribute

Allows `markdown`, `markdown="1"`, or `markdown="block"` to enable Markdown processing inside HTML elements. This includes Material for MkDocs grid cards pattern:

```markdown
<div class="grid cards" markdown>

-   :zap:{ .lg .middle } **Built for speed**

    ---

    Written in Rust for blazing fast performance.

</div>
```

Supported elements: `div`, `section`, `article`, `aside`, `details`, `figure`, `footer`, `header`, `main`, `nav`.

**Affected rules**: MD030 (list marker space), MD033 (inline HTML), MD035 (HR style)

### Code Block Title Attribute

MkDocs allows `title=` on fenced code blocks:

````markdown
```python title="example.py"
print("Hello")
```
````

**Affected rules**: MD040 (fenced code language)

### Table Extensions

MkDocs table handling with extensions like `md_in_html`:

**Affected rules**: MD056 (table column count)

### mkdocstrings Blocks

mkdocstrings autodoc syntax is recognized:

```markdown
::: module.path
    options:
        show_source: true

::: package.submodule.Class
```

**Affected rules**: MD031 (blanks around fences), MD038 (code spans)

### PyMdown Blocks

[PyMdown Blocks](https://facelessuser.github.io/pymdown-extensions/extensions/blocks/) syntax using `///` fences is recognized:

```markdown
/// details | Summary
    type: warning

Content inside the block.

///

/// caption
Figure 1: Example diagram
///

/// html | div.custom-class

Custom HTML content with markdown.

///
```

Block types include: `admonition`, `details`, `caption`, `html`, `tab`, and custom blocks.

**Affected rules**: MD012, MD018, MD022, MD025, MD030, MD033, MD036, MD057, MD059, MD064 (all skip content inside blocks)

### Extended Markdown Syntax

MkDocs extensions for special formatting:

```markdown
++inserted text++     <!-- ins extension -->
==marked text==       <!-- mark extension -->
^^superscript^^       <!-- caret extension -->
~subscript~           <!-- tilde extension -->
[[keyboard keys]]     <!-- keys extension -->
```

**Affected rules**: MD038 (code spans), MD049 (emphasis style), MD050 (strong style)

## Rule Behavior Changes

| Rule  | Standard Behavior                | MkDocs Behavior                         |
| ----- | -------------------------------- | --------------------------------------- |
| MD024 | Flag duplicate headings          | Skip headings in snippet sections       |
| MD030 | Check list marker spacing        | Skip inside markdown-enabled HTML       |
| MD031 | Require blanks around all fences | Respect admonition/tab/mkdocstrings     |
| MD033 | Flag all inline HTML             | Allow `markdown` attribute on elements  |
| MD035 | Check horizontal rule style      | Skip inside markdown-enabled HTML       |
| MD038 | Flag spaces in code spans        | Handle keys/caret/mark syntax           |
| MD040 | Require language on code blocks  | Allow `title=` without language         |
| MD042 | Flag empty links `[]()`          | Allow auto-references `[Class][]`       |
| MD046 | Detect code block style globally | Account for admonition/tab context      |
| MD049 | Check emphasis consistency       | Handle mark/inserted syntax             |
| MD050 | Check strong consistency         | Handle mark/caret/tilde syntax          |
| MD051 | Validate all fragment links       | Skip footnote and option anchors        |
| MD052 | Flag undefined references        | Allow auto-references and snippets      |
| MD056 | Strict column count              | Handle MkDocs table extensions          |
| MD077 | Content column W+N indent        | Enforce min 4-space continuation indent |

## Configuration

```toml
[global]
flavor = "mkdocs"
```

Or for specific directories:

```toml
[per-file-flavor]
"docs/**/*.md" = "mkdocs"
```

## When to Use

Use the MkDocs flavor when:

- Building documentation with MkDocs
- Using Material for MkDocs theme
- Using mkdocstrings for API documentation
- Using PyMdown Extensions

## Extension Support Reference

The MkDocs flavor provides lint-aware support for the common Python-Markdown and PyMdown Extensions used in the MkDocs ecosystem.

### Support Levels

Each extension has one of these support levels:

| Level | Meaning |
|-------|---------|
| Lint-safe | rumdl won't flag valid extension syntax as violations |
| Fix-safe | `--fix` preserves extension constructs unchanged |
| Format-aware | Reflow/formatting respects extension structure (e.g., preserves indentation during MD013 reflow) |

### Python-Markdown Extensions

| Extension | Level | Description |
|-----------|-------|-------------|
| [abbr](https://python-markdown.github.io/extensions/abbreviations/) | Lint-safe, Fix-safe | Abbreviation definitions `*[HTML]: Hypertext Markup Language` |
| [admonition](https://python-markdown.github.io/extensions/admonition/) | Format-aware | Admonition blocks `!!! note` with indentation-aware reflow |
| [attr_list](https://python-markdown.github.io/extensions/attr_list/) | Lint-safe, Fix-safe | Attribute lists `{#id .class}` |
| [def_list](https://python-markdown.github.io/extensions/definition_lists/) | Lint-safe, Fix-safe | Definition lists with `:` markers |
| [footnotes](https://python-markdown.github.io/extensions/footnotes/) | Lint-safe, Fix-safe | Footnotes `[^1]`, definitions, and anchor links `#fn:1` |
| [md_in_html](https://python-markdown.github.io/extensions/md_in_html/) | Lint-safe, Fix-safe | `markdown="1"` attribute on HTML elements |
| [toc](https://python-markdown.github.io/extensions/toc/) | Lint-safe, Fix-safe | `[TOC]` markers are preserved |
| [tables](https://python-markdown.github.io/extensions/tables/) | Lint-safe, Fix-safe | Standard table support |
| [meta](https://python-markdown.github.io/extensions/meta_data/) | Lint-safe, Fix-safe | YAML frontmatter detection |
| [fenced_code](https://python-markdown.github.io/extensions/fenced_code_blocks/) | Lint-safe, Fix-safe | Fenced code blocks with attributes |
| [codehilite](https://python-markdown.github.io/extensions/code_hilite/) | N/A | Rendering-only (no linting impact) |

### PyMdown Extensions

| Extension | Level | Description |
|-----------|-------|-------------|
| [arithmatex](https://facelessuser.github.io/pymdown-extensions/extensions/arithmatex/) | Lint-safe, Fix-safe | Math blocks `$$ ... $$` and inline `$...$` |
| [betterem](https://facelessuser.github.io/pymdown-extensions/extensions/betterem/) | Lint-safe, Fix-safe | Standard emphasis handling applies |
| [blocks](https://facelessuser.github.io/pymdown-extensions/extensions/blocks/) | Lint-safe, Fix-safe | PyMdown Blocks `/// type` with `///` fence syntax |
| [caret](https://facelessuser.github.io/pymdown-extensions/extensions/caret/) | Lint-safe, Fix-safe | Superscript `^text^` and insert `^^text^^` |
| [critic](https://facelessuser.github.io/pymdown-extensions/extensions/critic/) | Lint-safe, Fix-safe | Critic markup `{++add++}`, `{--del--}` |
| [details](https://facelessuser.github.io/pymdown-extensions/extensions/details/) | Lint-safe, Fix-safe | Collapsible blocks `??? note` and `???+ note` |
| [emoji](https://facelessuser.github.io/pymdown-extensions/extensions/emoji/) | Lint-safe, Fix-safe | Emoji/icon shortcodes `:material-check:` |
| [highlight](https://facelessuser.github.io/pymdown-extensions/extensions/highlight/) | N/A | Rendering-only (no linting impact) |
| [inlinehilite](https://facelessuser.github.io/pymdown-extensions/extensions/inlinehilite/) | Lint-safe, Fix-safe | Inline code highlighting `` `#!python code` `` |
| [keys](https://facelessuser.github.io/pymdown-extensions/extensions/keys/) | Lint-safe, Fix-safe | Keyboard keys `++ctrl+alt+del++` |
| [mark](https://facelessuser.github.io/pymdown-extensions/extensions/mark/) | Lint-safe, Fix-safe | Highlighted text `==text==` |
| [smartsymbols](https://facelessuser.github.io/pymdown-extensions/extensions/smartsymbols/) | Lint-safe, Fix-safe | Smart symbols `(c)`, `(tm)`, `-->` |
| [snippets](https://facelessuser.github.io/pymdown-extensions/extensions/snippets/) | Lint-safe, Fix-safe | File inclusion `--8<-- "file.md"` |
| [superfences](https://facelessuser.github.io/pymdown-extensions/extensions/superfences/) | Lint-safe, Fix-safe | Custom fences with language + attributes |
| [tabbed](https://facelessuser.github.io/pymdown-extensions/extensions/tabbed/) | Format-aware | Content tabs `=== "Tab"` with indentation-aware reflow |
| [tasklist](https://facelessuser.github.io/pymdown-extensions/extensions/tasklist/) | Lint-safe, Fix-safe | Task lists `- [x] Task` (standard GFM) |
| [tilde](https://facelessuser.github.io/pymdown-extensions/extensions/tilde/) | Lint-safe, Fix-safe | Subscript `~text~` and strikethrough `~~text~~` |

### mkdocstrings

| Feature | Level | Description |
|---------|-------|-------------|
| [Auto-doc blocks](https://mkdocstrings.github.io/) | Format-aware | `::: module.Class` with YAML options, indentation-aware reflow |
| [Cross-references](https://mkdocstrings.github.io/) | Lint-safe, Fix-safe | `[module.Class][]` reference links |

## See Also

- [Flavors Overview](../flavors.md) - Compare all flavors
- [MkDocs Documentation](https://www.mkdocs.org/)
- [Material for MkDocs](https://squidfunk.github.io/mkdocs-material/)
- [PyMdown Extensions](https://facelessuser.github.io/pymdown-extensions/)
- [mkdocstrings](https://mkdocstrings.github.io/)