Markdown Lint

VMark ships a built-in lint engine that catches correctness issues, not style preferences. Lint runs on demand (Cmd-Shift-L or Tools → Check Markdown) and surfaces results inline as gutter squiggles, with a status bar badge and F2 navigation between findings.

What lint is and isn't

VMark's lint is a correctness checker:

• Broken cross-references
• Undefined link / footnote references
• Unclosed code fences
• Tables with mismatched column counts
• Heading levels that skip (h1 → h3)
• Images without alt text
• Empty link text or empty href

VMark's lint is not a style enforcer. It will not flag:

• Line length
• List marker style (- vs *)
• Emphasis marker style (_ vs *)
• Heading style (# vs underline)
• Trailing whitespace

For style enforcement, use a separate tool like prettier --check outside VMark.

Rule Reference

Rule ID	Severity	Description
E01	Error	Undefined reference: [link][missing] points to a definition that doesn't exist
E02	Error	Table row has wrong column count (mismatch with header row)
E03	Error	Reversed link — looks like (text)[url] instead of [text](url)
E04	Error	ATX heading missing space after # (e.g., ##Heading should be ## Heading)
E05	Error	Space inside emphasis markers — * word * won't render as italic
E06	Error	Unclosed fenced code block — file ends with an open ``` fence
E07	Error	Duplicate link reference definition (same [label]: appears twice)
E08	Error	Empty link href — [text]()
W01	Warning	Heading level skipped (h2 expected, found h3)
W02	Warning	Image missing alt text — accessibility
W03	Warning	Unused link reference definition (defined but never linked)
W04	Warning	Anchor fragment doesn't match any heading — #section for a section that doesn't exist
W05	Warning	Empty link text — [](url)
M001	Error	Image file not found at the local path
M002	Error	Linked file not found at the local path
Y001	Error	YAML parse error (for YAML files)
Y002	Warning	YAML parse warning (for YAML files)

Triggering lint

Trigger	Action
Cmd + Shift + L (macOS) / Ctrl + Shift + L (Win/Linux)	Run lint on the active document
Tools → Check Markdown	Same as the shortcut
F2	Jump to the next diagnostic
Shift + F2	Jump to the previous diagnostic

For markdown files with file paths, link-existence checking runs automatically alongside the sync rules — see Link Check.

For YAML files, parse errors appear live in the gutter as you type, and the same Cmd-Shift-L shortcut populates the badge + F2 navigation.

Settings

The lint engine has a single user-facing toggle:

• Settings → Markdown → Enable markdown lint — turn the engine on or off entirely

When disabled, the shortcut becomes a no-op and no diagnostics appear in the gutter.

See also

• Link Check — broken local link / image detection
• Settings → Markdown → Lint