FMJL for VS Code

Support for FMJL .fmjl files. FMJL, short for Format, Markdown, JSON Lines, is a document format that combines four languages: JSON Lines as the container (one element per line), Markdown for all readable text, LaTeX for formulas, and HTML for tables with merged cells.

Features

• Convert without leaving VS Code. Right-click any .md file and choose FMJL: Convert Markdown to .fmjl; right-click any .fmjl file and choose FMJL: Convert .fmjl to Markdown. Both are also in the Command Palette (Ctrl+Shift+P). Element ids are kept across edits, so converting back and forth never renumbers anything.
• Recognizes .fmjl files and colors field names, element types, strings and numbers.
• Live error checking while you type, with red underlines and messages in the Problems panel: JSON mistakes, missing required fields, wrong types and subtypes, wrong hash and characters values, non-canonical Markdown, missing image files, duplicate ids and labels, broken parent / reference / continues links, dead [text](#label) links, page and bbox rules, and header rules.
• One-click fixes. Problems such as a wrong hash, a wrong characters count, a missing field or non-canonical Markdown show a light bulb: Fix with FMJL: Fill. The same command, FMJL: Fill, is in the right-click menu. It works like fmjl fill: existing ids never change, new elements get the next free id.
• Outline and breadcrumbs. Headings, groups, tables, images, formulas and code appear in the Outline view, nested by parent, with the page shown as people count it (page 0 is page 1).
• Hover over an element line to read its Markdown rendered, instead of the escaped JSON string. Hover over an id in parent, reference or continues to see the element it points to.
• Go to Definition (F12) on an id jumps to that element; Find All References (Shift+F12) lists its children and everything that references it.
• Command FMJL: Check current file for a clear PASSED / FAILED answer. The live checker reports the same problems as fmjl check, including \r\n line endings, a byte-order mark and a missing newline at the end; test/checker.js proves it.
• Converting asks first before it would lose work: when a .md without id notes would replace an existing .fmjl (every id would change), or when the .md was edited after the .fmjl.

How to use it

1. Write a normal Markdown file, for example notes.md. Put images in an images/ folder next to it.
2. Right-click the file, FMJL: Convert Markdown to .fmjl. notes.fmjl opens with a PASSED or FAILED message.
3. To edit later, right-click notes.fmjl, FMJL: Convert .fmjl to Markdown, change the text, and convert back. Unchanged elements keep their ids and hashes.

Notes

• The converter is pure JavaScript and needs no Python. Its output is byte-identical to the reference Python package fmjl; npm test checks that on every document in the repository.
• The rulebook is the authority. If this extension and the rulebook disagree, the extension has a bug: https://github.com/rupakkumar-76319/fmjl/issues

The format

FMJL stores any document as elements (headings, paragraphs, lists, tables, formulas, code, images, captions, footnotes, stamps, watermarks...) with ids, hashes, pages, positions and permissions - built for RAG systems and search.

Markdown alone cannot record an image's page, link a caption to its image, or say who may read a paragraph. JSON alone is unreadable for people. LaTeX alone is slow and hard to write. HTML alone is heavy. FMJL keeps the strength of each. See the rulebook: rulebook/fmjl_rulebook_v1.1.md, or read it at https://rupakkumar-76319.github.io/fmjl/rulebook.html