markdown-accessibility

---
name: markdown-accessibility
description: Audit and fix markdown for accessibility. Covers ambiguous links, anchors, emoji (remove/translate), Mermaid/ASCII templates, heading hierarchy, table descriptions, and severity scoring.
license: MIT
---

# Markdown Accessibility Skill

Reusable knowledge module for the `markdown-a11y-assistant`, `markdown-scanner`, and `markdown-fixer` agents and the `markdown-accessibility` always-on instructions. Provides pattern libraries, severity scoring, fix templates, emoji translation maps, diagram description templates, and GitHub anchor generation rules for comprehensive markdown accessibility auditing across 9 domains.

## Domains Covered

1. **Descriptive Links** (WCAG 2.4.4) - Ambiguous link text, bare URLs, repeated identical text
2. **Image Alt Text** (WCAG 1.1.1) - Missing, empty, filename-as-alt, generic placeholders
3. **Heading Hierarchy** (WCAG 1.3.1 / 2.4.6) - Skipped levels, multiple H1s, bold-as-heading
4. **Table Accessibility** (WCAG 1.3.1) - Missing descriptions, empty headers, layout tables
5. **Emoji** (WCAG 1.3.3 / Cognitive) - Remove-all, remove-decorative, translate, or leave-unchanged modes
6. **Mermaid and ASCII Diagrams** (WCAG 1.1.1 / 1.3.1) - Replace with accessible text + collapsible source
7. **Em-Dash / En-Dash Normalization** (Cognitive) - Normalize to ` - ` or leave unchanged
8. **Anchor Link Validation** (WCAG 2.4.4) - Validate `#anchor` links against actual headings
9. **Plain Language and List Structure** (Cognitive) - Emoji bullets, passive voice, sentence length

## Severity Scoring

| Issue | Severity | WCAG | Auto-fix? |
|-------|----------|------|-----------|
| Image missing alt text | Critical | 1.1.1 (A) | No - needs visual judgment |
| Mermaid diagram with no text alternative | Critical | 1.1.1 (A) | Partial - simple diagrams auto-described; complex need human |
| ASCII diagram with no text description | Critical | 1.1.1 (A) | Partial - flag and wrap; description needs human or auto-gen |
| Broken anchor link | Serious | 2.4.4 (A) | No - confirm which end changes |
| Ambiguous link text ("here", "click here") | Serious | 2.4.4 (A) | Yes - rewrite using surrounding context |
| Skipped heading level | Serious | 1.3.1 (A) | Yes - interpolate missing level |
| Multiple H1s | Serious | 1.3.1 (A) | Yes - demote all but first |
| Emoji in heading | Moderate | Cognitive | Yes - remove or translate per preference |
| Consecutive emoji (2+) | Moderate | 1.3.3 (A) | Yes - remove sequence or translate |
| Emoji used as bullet | Moderate | 1.3.1 (A) | Yes - replace with `-` |
| Em-dash in prose | Moderate | Cognitive | Yes - replace with ` - ` |
| Table without preceding description | Moderate | 1.3.1 (A) | Yes - add one-sentence summary |
| Bold text used as heading | Minor | 2.4.6 (AA) | Yes - convert to appropriate heading |
| Bare URL in prose | Minor | 2.4.4 (A) | Yes - wrap with descriptive text |
| Emoji used for meaning, single inline | Minor | 1.3.3 (A) | Conditional - remove-all: yes; remove-decorative: flag; translate: translate |

### Scoring Formula

```text
File Score = 100 - (sum of weighted findings)

Critical: -15 pts each
Serious:  - 7 pts each
Moderate: - 3 pts each
Minor:    - 1 pt each

Floor: 0
```

### Score Grades

| Score | Grade | Meaning |
|-------|-------|---------|
| 90-100 | A | Excellent - accessible documentation |
| 75-89 | B | Good - minor issues |
| 50-74 | C | Needs Work - several barriers |
| 25-49 | D | Poor - significant barriers |
| 0-24 | F | Failing - critical AT barriers |

## Emoji Handling Modes

The agent supports four modes. The **active mode is determined by the nearest `markdown-accessibility.instructions.md` file** in scope. If no instructions file sets a mode, the default is `remove-decorative`.

> **This repository:** The `.github/instructions/markdown-accessibility.instructions.md` file in this repo sets mode to **`remove-all`**. All emoji are removed, not translated. This overrides the skill default.

| Mode | Description | Default? |
|------|-------------|----------|
| `remove-all` | Strip every emoji from prose, headings, and bullets. Keep surrounding plain-text meaning. | No (repo override sets this) |
| `remove-decorative` | Remove emoji in headings, bullets, and consecutive sequences; flag single inline for review | **Skill default (no override)** |
| `translate` | Replace known emoji with `(English)` text; flag unknown for review | No |
| `leave-unchanged` | Do not flag or modify any emoji | No |

**Mode resolution order:**

1. Agent system prompt or per-task explicit mode override
2. Nearest `*.instructions.md` file in scope (e.g., `.github/instructions/markdown-accessibility.instructions.md`)
3. Skill default (`remove-decorative`)

### Emoji Translation Map

When using `translate` mode, replace each emoji with the parenthesized English equivalent:

| Emoji | Translation | Emoji | Translation |
|-------|------------|-------|------------|
| 🚀 | (Launch) | ✅ | (Done) |
| ⚠️ | (Warning) | ❌ | (Error) |
| 📝 | (Note) | 💡 | (Tip) |
| 🔧 | (Configuration) | 📚 | (Documentation) |
| 🎯 | (Goal) | ✨ | (New) |
| 🔍 | (Search) | 🛠️ | (Tools) |
| 👋 | (Hello) | 🎉 | (Celebration) |
| ⭐ | (Featured) | 💬 | (Discussion) |
| 🏠 | (Home) | 📊 | (Data) |
| 🔒 | (Security) | 🌐 | (Web) |
| 📦 | (Package) | 🔗 | (Link) |
| 📋 | (Checklist) | 🏆 | (Achievement) |
| ⚡ | (Quick) | 👍 | (Approved) |
| 👎 | (Rejected) | 🐛 | (Bug) |
| 🤝 | (Collaboration) | 🎓 | (Learning) |
| 🔑 | (Key) | 📌 | (Pinned) |
| ℹ️ | (Info) | 🔄 | (Refresh) |
| ➕ | (Add) | ➖ | (Remove) |
| 💻 | (Code) | 🔔 | (Notification) |
| 📣 | (Announcement) | 🧪 | (Test) |
| 🎨 | (Design) | 🌟 | (Highlight) |
| 📈 | (Increase) | 📉 | (Decrease) |
| 🏗️ | (Build) | 🔐 | (Locked) |
| 📂 | (Folder) | 📁 | (Folder) |
| 🗂️ | (Category) | 🗃️ | (Archive) |
| ⚙️ | (Settings) | 🏁 | (Finish) |
| 🚧 | (In Progress) | 🚫 | (Not Allowed) |
| ✔️ | (Check) | ➡️ | (Next) |
| ⬆️ | (Up) | ⬇️ | (Down) |

For emoji not in this table: flag as `needs-human-review`. Do not guess.

### Emoji Detection Unicode Ranges

```text
[\u{1F600}-\u{1F64F}]  - Emoticons
[\u{1F300}-\u{1F5FF}]  - Misc symbols and pictographs
[\u{1F680}-\u{1F6FF}]  - Transport and map symbols
[\u{1F700}-\u{1F77F}]  - Alchemical symbols
[\u{1F780}-\u{1F7FF}]  - Geometric shapes extended
[\u{1F900}-\u{1F9FF}]  - Supplemental symbols
[\u{1FA70}-\u{1FAFF}]  - Symbols and pictographs extended
[\u{2600}-\u{26FF}]    - Misc symbols
[\u{2700}-\u{27BF}]    - Dingbats
[\u{1F1E0}-\u{1F1FF}]  - Flags
[\u{FE00}-\u{FE0F}]    - Variation selectors
```

Emoji-as-bullet pattern: list item where the first non-whitespace character is an emoji.

## Pattern Library: Mermaid and ASCII Diagrams

### Mermaid Detection

Lines matching ` ```mermaid` (with optional leading spaces/tabs).

### Mermaid Description Templates

| Type | Description Template |
|------|---------------------|
| `graph TD/LR/RL/BT` / `flowchart` | "The following [direction] diagram shows: [list major nodes and connections from source]" |
| `sequenceDiagram` | "The following sequence diagram shows the interaction between [participants]: [list each message in order]" |
| `classDiagram` | "The following class diagram shows [N] classes: [list class names, key properties, and relationships]" |
| `erDiagram` | "The following entity-relationship diagram shows [entities] with these relationships: [list relationships]" |
| `gantt` | "The following Gantt chart shows project tasks: [list section names and tasks with dates if available]" |
| `pie` | "The following pie chart shows [title] with values: [list each label and percentage/value if available]" |
| `stateDiagram` | "The following state diagram shows [N] states: [list state names and transition triggers]" |
| `mindmap` | "The following mind map shows [root topic] with branches: [list top-level branch names]" |
| `timeline` | "The following timeline shows events: [list events in chronological order]" |

Auto-generate description for: `graph`, `flowchart`, `pie`, `gantt`, `mindmap`, `timeline`.
Flag for human review: `sequenceDiagram`, `classDiagram`, `erDiagram`, `stateDiagram` (complex enough to need human verification).

### Mermaid Replacement Template

```markdown
[Generated or user-provided text description - this is the primary accessible content]

<details>
<summary>Diagram source (Mermaid)</summary>

```mermaid
[original diagram source - unchanged]
```text

</details>
```

### ASCII Diagram Detection

ASCII art patterns: non-code-block lines (or unnamed code blocks) containing combinations of `+`, `-`, `|`, `/`, `\`, `>`, `<`, `^`, `v`, `*` forming a visual structure. Minimum 3 lines with consistent column alignment.

### ASCII Diagram Replacement Template

```markdown
[Generated or user-provided text description - this is the primary accessible content]

<details>
<summary>ASCII diagram</summary>

```

[original ASCII art - unchanged]

```html

</details>
```

## Pattern Library: Ambiguous Link Detection

Match these patterns (case-insensitive, trim whitespace):

### Exact-match violations

```text
here, click here, read more, learn more, more, more info,
link, details, info, go, see more, continue, start, download,
view, open, submit, this, that
```

### Starts-with violations

```text
click here to ..., read more about ..., learn more about ...,
here to ..., see more ...
```

### URL-as-text pattern

Any link where visible text matches `https?://` or `www\.`

### Repeated identical text

Multiple `[X](url1)` and `[X](url2)` with same X but different URLs on the same page.

### Safe patterns (do not flag)

- Badge links: `[![text](img)](url)` at top of README
- Section self-references: `[Installation](#installation)` where text matches heading
- Footer resource lists using the resource/tool name as text

## Pattern Library: GitHub Anchor Generation

GitHub converts headings to anchor IDs using these rules:

1. Lowercase entire string
2. Remove all characters except: letters (a-z), digits (0-9), spaces, hyphens
3. Replace spaces with hyphens
4. Remove leading and trailing hyphens

### Examples

| Heading | Anchor |
|---------|--------|
| `# Getting Started` | `#getting-started` |
| `## API: v2.0 Reference` | `#api-v20-reference` |
| `### What's New?` | `#whats-new` |
| `## C# and .NET Support` | `#c-and-net-support` |
| `## Step 1: Installation` | `#step-1-installation` |
| `## FAQ (Frequently Asked Questions)` | `#faq-frequently-asked-questions` |
| `## 🚀 Quick Start` | `#-quick-start` (emoji becomes empty, may vary) |

For headings containing emoji: GitHub strips the emoji character and generates an anchor from the remaining text. Anchors referencing emoji-containing headings are fragile and should be flagged.

## Pattern Library: Emoji Detection

Unicode emoji ranges for regex detection:

```text
[\u{1F600}-\u{1F64F}]  # Emoticons
[\u{1F300}-\u{1F5FF}]  # Misc symbols and pictographs
[\u{1F680}-\u{1F6FF}]  # Transport and map symbols
[\u{1F700}-\u{1F77F}]  # Alchemical symbols
[\u{1F780}-\u{1F7FF}]  # Geometric shapes extended
[\u{1F800}-\u{1F8FF}]  # Supplemental arrows-C
[\u{1F900}-\u{1F9FF}]  # Supplemental symbols and pictographs
[\u{1FA00}-\u{1FA6F}]  # Chess symbols
[\u{1FA70}-\u{1FAFF}]  # Symbols and pictographs extended-A
[\u{2600}-\u{26FF}]    # Misc symbols
[\u{2700}-\u{27BF}]    # Dingbats
[\u{FE00}-\u{FE0F}]    # Variation selectors
[\u{1F1E0}-\u{1F1FF}]  # Flags
```

Emoji-as-bullet pattern: List item where first non-whitespace character is an emoji.

## Pattern Library: Em-Dash and En-Dash

Detection patterns:

```text
—           Unicode em-dash (U+2014)
–           Unicode en-dash (U+2013)
---         Three hyphens in prose (not on its own line as HR)
--          Two hyphens in prose (used as em-dash substitute)
```

Safe to skip (do not modify):

- Line containing only `---` (horizontal rule)
- Content inside ` ``` ` code fences
- Content inside backtick inline code
- YAML front matter block
- HTML comment blocks `<!-- -->`

Replacement: ` - ` (space + hyphen + space)

En-dash in numeric ranges: `2–4 hours` -> `2 - 4 hours`

## Pattern Library: Mermaid Diagrams

Detection: Lines matching ` ```mermaid` (with optional leading spaces/tabs)

Diagram types and description guidance:

| Type | Description Template |
|------|---------------------|
| `graph TD/LR/RL/BT` | "The following diagram shows a [direction] flowchart: [list major nodes and connections]" |
| `sequenceDiagram` | "The following sequence diagram shows the interaction between [participants]: [list message exchanges]" |
| `classDiagram` | "The following class diagram shows [N] classes: [list class names and key relationships]" |
| `erDiagram` | "The following entity-relationship diagram shows [entities] and their relationships: [list relationships]" |
| `gantt` | "The following Gantt chart shows project phases: [list tasks and timeframes]" |
| `pie` | "The following pie chart shows [title] with values: [list segment names and values if available]" |
| `stateDiagram` | "The following state diagram shows [N] states and transitions: [list states and transition triggers]" |

Wrapping template:

```markdown
[Generated or user-provided text description]

<details>
<summary>Diagram source (Mermaid)</summary>

```mermaid
[original diagram source]
```text

</details>
```

## Fix Templates

### Ambiguous link fix

```markdown
# Before
For more information, see [here](https://example.com/guide).

# After
For more information, see the [installation guide](https://example.com/guide).
```

### Emoji bullet fix

```markdown
# Before
- 🚀 Deploy to production
- ✅ Run tests

# After
- Deploy to production
- Run tests
```

### Emoji heading fix

```markdown
# Before
## 🔧 Configuration

# After
## Configuration
```

### Em-dash fix

```markdown
# Before
The agent—when invoked—will scan all files.

# After
The agent - when invoked - will scan all files.
```

### Table description fix

```markdown
# Before
| Rule | Severity | Auto-fix |
|------|----------|----------|

# After
The following table lists rules with their severity level and whether they can be fixed automatically.

| Rule | Severity | Auto-fix |
|------|----------|----------|
```

### Broken anchor fix

```markdown
# Before (broken)
See [Installation](#instalation) for setup steps.

# Heading in file
## Installation

# After (corrected)
See [Installation](#installation) for setup steps.
```

## Markdownlint Rules Reference

| Rule | Name | Accessibility Relevance |
|------|------|------------------------|
| MD001 | heading-increment | Heading hierarchy (WCAG 1.3.1) |
| MD022 | blanks-around-headings | Parsing reliability |
| MD024 | no-duplicate-heading | Unique section identity (WCAG 2.4.6) |
| MD025 | single-title / single-h1 | One H1 per document |
| MD033 | no-inline-html | May hide structure from parsers |
| MD034 | no-bare-urls | Ambiguous links (WCAG 2.4.4) |
| MD041 | first-line-heading | Document structure |
| MD055 | table-pipe-style | Table parsing consistency |
| MD056 | table-column-count | Table structural integrity |

Command: `npx --yes markdownlint-cli2 <filepath>`