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Mdserve

Documents
mdserve

Mdserve is an Agent Skill for documents published in the jfernandez/mdserve repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Preview markdown with mdserve when content is long or likely to be iterated with the user (tables, diagrams, multi-section docs). Skip preview for short markdown that is easy to read directly in the terminal.

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How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy and paste the prompt below.
  3. Review files and risks before approving any action.
Prompt to paste
Inspect the Agent Skill at https://github.com/jfernandez/mdserve/blob/HEAD/skills/mdserve/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/mdserve, but wait for my approval before writing files or running scripts.

Copying this prompt does not install or run the skill. Review third-party files before use.

mdserve

Serve markdown files as live-reloading HTML previews in the browser using mdserve.

When to use

Use mdserve whenever you produce markdown that benefits from rendered presentation:

  • Plans and proposals
  • Architecture or design documents
  • Reports, comparisons, or summaries with tables
  • Anything containing Mermaid diagrams
  • Multi-file documentation sets
  • Any time the user asks to "preview" or "render" markdown

Use mdserve when markdown is more than about 40 to 60 lines, has complex formatting, or is likely to go through multiple edit/review iterations with the user.

Do not use mdserve for short conversational answers, single code snippets, trivial one-paragraph responses, or any markdown that fits comfortably within a terminal window.

Workflow

  1. Write the markdown file (e.g. plan.md).
  2. Start mdserve using the Bash tool with run_in_background: true and the --open flag to launch the browser automatically: 
    command: mdserve --open plan.md
run_in_background: true
  3. Tell the user the URL (default: http://127.0.0.1:3000).
  4. Continue editing the file - changes reload automatically.
  5. When the task is finished and the preview is no longer needed, stop the background task using TaskStop with the task ID.

Port conflicts

mdserve automatically finds an available port if the default (3000) is in use. Check the startup output for the actual URL and always tell the user the URL that mdserve reports.

Directory mode

When producing multiple related markdown files, serve the parent directory instead:

command: mdserve --open docs/
run_in_background: true

This gives the user a sidebar to navigate between files. Only the immediate directory is watched (non-recursive).

Mermaid diagrams

Use Mermaid diagrams when they improve clarity over plain text:

  • Flowcharts — processes and decision trees
  • Sequence diagrams — API and service interactions
  • Entity-relationship diagrams — data models
  • State diagrams — state machines

Prefer Mermaid over ASCII art when the diagram has more than a few elements or shows relationships and flow.

Installation

mdserve must be installed on the user's system. If the mdserve command is not found, ask the user how they would like to install it using AskUserQuestion with these options:

  1. Install script — curl -sSfL https://raw.githubusercontent.com/jfernandez/mdserve/main/install.sh | bash
  2. Homebrew — brew install mdserve
  3. Cargo — cargo install mdserve
  4. Arch Linux — sudo pacman -S mdserve

Then run the corresponding install command for them.