markedit

A support guide for MarkEdit, a free macOS app for editing Markdown, a plain-text format for formatted documents. It covers the app’s settings, extensions, themes, scripts, and related files.

In plain words
What is it for?
Use it to install or upgrade extensions, submit extensions or themes, customize editor behavior and styles, and troubleshoot MarkEdit.
Why use it?
It gives users a reference for changing MarkEdit, keeping extensions current, and diagnosing configuration problems. It also explains where supporting files are stored.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/markedit-app/markedit-skill/markedit
Any agent
npx skills add MarkEdit-app/MarkEdit-skill --skill markedit
Clone the repo
git clone --depth 1 https://github.com/MarkEdit-app/MarkEdit-skill

Made for: Claude Code, Codex.

Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,065 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00025 $0.03065
Opus 5 $0.00013 $0.01533
Sonnet 5 $0.00005 $0.00613
Haiku 4.5 $0.00003 $0.00307

Measured yesterday against content hash 0354b81f3219, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

markedit scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -fsSL -o file "<url>" && shasum -a 256 file
markedit/SKILL.md · 243 lines

How it starts

The opening of the file, as written. The whole thing — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

Help users configure and extend MarkEdit, a free and open-source markdown editor for macOS.

Key Capabilities

  • Upgrade the MarkEdit app
  • Install, upgrade, and manage MarkEdit extensions
  • Submit extensions and themes to the official registry
  • Configure MarkEdit settings and supporting files
  • Troubleshoot MarkEdit issues
  • Answer questions related to MarkEdit

Core Concepts

File Locations

Path Description
~/Library/Containers/app.cyan.markedit/Data/Documents/scripts/ Extensions directory
~/Library/Containers/app.cyan.markedit/Data/Documents/extensions.json Installed extension metadata
~/Library/Containers/app.cyan.markedit/Data/Documents/settings.json Advanced settings
~/Library/Containers/app.cyan.markedit/Data/Documents/editor.css Custom stylesheets
~/Library/Containers/app.cyan.markedit/Data/Documents/editor.js Custom JavaScript
~/Library/Containers/app.cyan.markedit/Data/Documents/statistics-rules.json Custom statistics rules
~/Library/Containers/app.cyan.markedit/Data/Documents/pandoc.yaml Pandoc defaults
~/Library/Containers/app.cyan.markedit/Data/Documents/debug/ Troubleshooting information

Extension Registry

Use the official registry metadata:

https://raw.githubusercontent.com/MarkEdit-app/extensions/main/index.json

The registry website is useful for browsing. For installation and upgrades, fetch index.json from registry.url in extensions.json, using the official URL above only when that field is absent or null. Do not fall back when extensions.json is malformed. Match the user's request against each entry's name, description, and ID. If multiple entries match, ask the user to choose.

Each entry's latest object provides version, immutable asset url, sha256, and optional minAppVersion. Accept registry schemaVersion values up to 1; stop on a newer version. Require an HTTPS asset URL, a safe kebab-case ID, and a compatible MarkEdit version before installation.

Read the full file on GitHub · 243 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 243 lines · 25 tokens per session scan A 0354b81f3219

Subscribe to this mod's changes

markedit is a skill published in the GitHub repository MarkEdit-app/MarkEdit-skill (5 stars, last pushed 9d ago), licensed MIT. It adds 25 tokens to every session and 3,065 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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