rumdl 0.1.76

A fast Markdown linter written in Rust (Ru(st) MarkDown Linter)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

# MD018 - No missing space after hash in heading

Aliases: `no-missing-space-atx`

## What this rule does

Ensures there's a space between the # symbols and the heading text.

## Why this matters

- **Readability**: Headings without spaces look cramped and are harder to read
- **Compatibility**: Some Markdown processors won't recognize headings without spaces
- **Standards**: Proper spacing follows Markdown best practices

## Examples

### ✅ Correct

<!-- rumdl-disable MD022 -->

```markdown
# Heading 1
## Heading 2
### Heading 3
#### Heading 4
##### Heading 5
###### Heading 6
```

<!-- rumdl-enable MD022 -->

### ❌ Incorrect

<!-- rumdl-disable MD018 MD022 -->

```markdown
#Heading 1
##Heading 2
###Heading 3
####Heading 4
#####Heading 5
######Heading 6
```

<!-- rumdl-enable MD018 MD022 -->

### 🔧 Fixed

<!-- rumdl-disable MD022 -->

```markdown
# Heading 1
## Heading 2
### Heading 3
#### Heading 4
##### Heading 5
###### Heading 6
```

<!-- rumdl-enable MD022 -->

## Configuration

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| `magiclink` | boolean | `false` | Enable MagicLink support for issue/PR references |
| `tags` | boolean | `null` | Recognize `#word` as tags instead of malformed headings. Defaults to `true` for Obsidian flavor, `false` otherwise |

### MagicLink support

When `magiclink = true`, this rule skips [PyMdown MagicLink](https://facelessuser.github.io/pymdown-extensions/extensions/magiclink/) issue/PR references at the start of a line. This prevents false positives when using MagicLink's auto-linking syntax for patterns like `#123`.

```toml
[MD018]
magiclink = true
```

#### Example

<!-- rumdl-disable MD018 MD022 MD025 -->

```markdown
# PRs that are helpful for context

#10 discusses the philosophy behind the project, and #37 shows a good example.

#Summary
```

<!-- rumdl-enable MD018 MD022 MD025 -->

With `magiclink = true`:

- `#10` and `#37` are **not flagged** (MagicLink issue references)
- `#Summary` is **flagged** (non-numeric, likely a malformed heading)

## Special cases

This rule correctly handles:

- Emoji hashtags like #️⃣ and #⃣ (not treated as headings)
- Content inside HTML blocks and comments (e.g., CSS selectors like `#id`)
- YAML frontmatter comments
- Indented patterns (not at column 1)

## Tag syntax support

When `tags = true`, this rule skips `#word` patterns that look like tags (e.g., `#todo`, `#project/active`) instead of treating them as malformed headings.

Tags are recognized when they start with `#` followed by a non-digit, non-space character. Multi-hash patterns like `##tag` are always treated as malformed headings, and `#123` (starting with a digit) is not a valid tag.

When `tags` is not explicitly set, it defaults to `true` for Obsidian flavor and `false` otherwise. This means Obsidian users get tag support automatically, while users of other flavors can opt in:

```toml
[MD018]
tags = true
```

### Example

<!-- rumdl-disable MD018 MD022 MD025 -->

```markdown
# Real Heading

#todo this is a tag

#project/active nested tag

##Introduction
```

<!-- rumdl-enable MD018 MD022 MD025 -->

With `tags = true`:

- `#todo` and `#project/active` are **not flagged** (recognized as tags)
- `##Introduction` is **flagged** (multi-hash, clearly a malformed heading)
- `#123` is **flagged** (tags cannot start with digits)

## Automatic fixes

This rule automatically adds a space after the # symbols to properly format the heading.

## Learn more

- [CommonMark specification for headings](https://spec.commonmark.org/0.31.2/#atx-headings) - Technical details about heading syntax

## Related rules

- [MD019](md019.md) - No multiple spaces after hash in heading
- [MD020](md020.md) - No missing space in closed heading
- [MD021](md021.md) - No multiple spaces in closed heading
- [MD022](md022.md) - Headings should be surrounded by blank lines