Hyday Markdown Skill

First time in this conversation? Run Step 0 from hyday-vault-layout to find the vault root. This skill assumes you already know where the user's Hyday folder lives on disk. Resolve it from ~/Library/Application Support/Hyday/settings.json (macOS) or %APPDATA%\Hyday\settings.json (Windows) — journalPath field. Don't guess, don't write to ~/Documents/Hyday, and don't ask the user unless the config file lookup fails.

Hyday stores every note as a plain .md file on disk. The app picks up changes automatically — write the file, and the note appears in Hyday next time it scans. This skill covers Hyday's extensions on top of standard Markdown.

Assumed knowledge: CommonMark + GFM (headings, lists, tables, code blocks, task lists - [ ]). Only Hyday-specific syntax is documented here.

Workflow: Creating a Hyday Note

1. Pick the right file name. Notes use any descriptive filename ending in .md. Avoid names that look like a date (YYYY-MM-DD.md, YYYY.MM.DD.md) unless the file is meant to be a [[journal entry]] — Hyday auto-detects those as the journal type. See hyday-vault-layout for where the file goes.
2. Write frontmatter at the top of the file using YAML between --- fences. Always quote string values with double quotes.
3. Pick a type from article | card | img | link | video. Default is article if omitted. Journal files do not use type — Hyday infers journal from the filename.
4. Write the body in Markdown. Add #tag, @(Label), and [[note-id]] inline as needed.
5. Save the file. Hyday reindexes within a few seconds.

Frontmatter