Save as Markdown

Write the named source to a .md file, in full, and say where it is. The body comes from the fetched bytes, never from a summary.

• IS: one named source (URL, attachment, paste, YouTube video, Google Doc, PDF) to one .md in the user's tree.
• IS NOT: answering from a fetch, summarizing into chat, crawling beyond the URLs named, or reconstructing a talk from memory.

Done

A .md exists where the user can open it, with this frontmatter, and reading it back returns the source's last paragraph:

---
title: "<title>"
source: "<URL or path>"
date: "<date -u +%Y-%m-%dT%H:%M:%SZ, run now>"
type: web | youtube | gdoc | sheet | slides | pdf | docx | tweet | conversation
---