Markdown Lint
VMark ships a built-in lint engine that catches correctness issues, not style preferences. Lint runs on demand (Alt + Mod + V or View → Check Markdown) and surfaces results inline — a coloured bar down the side of each affected block in WYSIWYG mode, a wavy underline under the exact text in Source mode — 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 references (footnote references are not checked)
- 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 | Warning | Space inside emphasis markers — * word * won't render as italic (arithmetic-shaped expressions such as 3 * 4 * 5 or x * y * z — short operands surrounding both stars — are treated as multiplication and not flagged) |
| E06 | Error | Empty link text — [](url) |
| E07 | Error | Duplicate link reference definition (same [label]: appears twice) |
| E08 | Error | Unclosed fenced code block — file ends with an open ``` fence |
| 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 href — [text]() |
| 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
Mod = Cmd on macOS, Ctrl on Windows/Linux; Alt = Option on macOS.
| Trigger | Action |
|---|---|
Alt + Mod + V | Run lint on the active document |
| View → 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 Alt + Mod + V 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 editor.
See also
- Link Check — broken local link / image detection
- Settings → Markdown → Lint