markdown-formatting

Enforces markdown line-wrap and structure rules for clean git diffs

Night Market Skill — ported from claude-night-market/leyline. For the full experience with agents, hooks, and commands, install the Claude Code plugin.

Markdown Formatting Conventions

When To Use

• Writing or editing any markdown documentation
• Reviewing prose for line-wrapping compliance
• Generating markdown from plugins (scribe, sanctum, etc.)

When NOT To Use

• Editing code blocks, tables, or frontmatter (these have their own formatting rules)
• Quick scratch notes that will not be committed

These conventions apply to all markdown documentation generated or modified by any plugin. The goal: produce prose that creates clean, reviewable git diffs and reads well on mobile devices.

Quick Reference

When writing or editing markdown prose:

1. Wrap prose at 80 chars using hybrid wrapping (prefer sentence/clause boundaries over arbitrary word breaks)
2. Blank line before and after every heading
3. ATX headings only (# Heading, never setext underlines)
4. Blank line before every list
5. Reference-style links when inline links push lines beyond 80 chars

What to Wrap

Wrap these content types at 80 characters:

• Paragraphs (flowing prose text)
• Blockquote text (the content after >)
• List item descriptions (text after - or 1. )
• Descriptions in definition lists

What NOT to Wrap

Never wrap or reflow these content types:

• Tables: pipe-delimited rows stay on one line
• Code blocks: fenced (```) or indented content
• Headings: lines starting with #
• Frontmatter: YAML/TOML between --- or +++
• HTML blocks: raw HTML elements
• Link definitions: [id]: url reference lines
• Image references: ![alt](url) on their own line
• Single-line list items: short bullets that fit on one line

Wrapping Algorithm (Summary)

For each prose paragraph:

1. If a sentence fits within 80 chars, keep it on one line
2. If a sentence exceeds 80 chars, break at the nearest sentence boundary (. ! ? ) before column 80
3. If no sentence boundary, break at the nearest clause boundary (, ; : ) before column 80
4. If no clause boundary, break before a conjunction (and but or ) before column 80
5. If none of the above, break at the last word boundary before column 80
6. Never break inside backtick spans, link text, or URLs

See modules/wrapping-rules.md for the full algorithm with examples.

Structural Rules

Blank Lines Around Headings

markdown

WRONG:
Some text.
## Heading
More text.

RIGHT:
Some text.

## Heading

More text.

Exception: the first line of a file may be a heading without a preceding blank line.

ATX Headings Only

markdown

WRONG:
Heading
=======

WRONG:
Subheading
----------

RIGHT:
# Heading

RIGHT:
## Subheading

Blank Line Before Lists

markdown

WRONG:
Some introductory text:
- Item one
- Item two

RIGHT:
Some introductory text:

- Item one
- Item two

Reference-Style Links for Long URLs

When an inline link pushes a line beyond 80 characters, use reference-style syntax:

markdown

WRONG (line too long):
See the [formatting guide](https://google.github.io/styleguide/docguide/style.html) for details.

RIGHT:
See the [formatting guide][fmt-guide] for details.

[fmt-guide]: https://google.github.io/styleguide/docguide/style.html

Place link definitions at the end of the current section or at the end of the document. When the same URL appears multiple times, use a single shared reference definition.

Short inline links that keep the line under 80 chars are fine:

markdown

OK:
See [the guide](https://example.com) for details.