Front Matter

Files can start with YAML front matter between --- delimiters. It serves two roles:

1. Document metadata — injected as template variables at render start
2. Component prop contracts — type, required flag, and defaults (see Includes and components)

Document metadata

---
title: About us
author: Team
---

# {{ title }}

Written by {{ author }}.

By default, front matter is stripped from output. Set preserveFrontMatter: true in render options to keep it.

Size limit

Front matter source must be ≤ 64 KB. Larger files throw frontmatter_too_large.

Component props contract

Define props in a component file's front matter:

---
props:
  name:
    type: string
    isRequired: true
    default: "Guest"
  count:
    type: number
---

Omitting type infers from the default value or passed value.

Scoping

Later bindings override earlier ones with the same name:

1. API context
2. File front matter
3. @hg declarations
4. Component call props (inside the component)

Component as aliases are an exception — they cannot collide. See Includes and components.

Security note

Do not store secrets in front matter. Use serverContext on the server instead. See Paths and security.