Prompt File Tools

Syntax highlighting and validation for structured prompt files in Visual Studio Code.

This extension adds editor support for .prmpt.md files, including syntax highlighting, YAML frontmatter awareness, role-block parsing for chat prompts, variable highlighting, and inline diagnostics for common formatting and validation errors.

Once installed, any file ending in .prmpt.md is recognized with syntax highlighting and inline diagnostics.

Features

• Dedicated prmptmd language for .prmpt.md files.
• YAML frontmatter highlighting.
• Chat role highlighting for system:, user:, assistant:, and developer: blocks.
• Variable highlighting for placeholders such as {{question}}.
• Diagnostics for invalid frontmatter fields, invalid type values, and malformed chat role markers.

PrmptMD Syntax

A PrmptMD file has two parts:

1. A required YAML frontmatter block, delimited by --- lines.
2. A body whose shape depends on the frontmatter type.

Frontmatter

---
description: Short human-readable description of what this prompt does.
type: chat
---

Allowed fields:

The frontmatter must:

• Start on the very first line of the file with ---.
• End with a closing --- on its own line.
• Be valid YAML.

The prompt name comes from the containing folder name, and the prompt version comes from the file name (for example v1.prmpt.md). These are not declared in frontmatter.

Body — type: prompt

The body is plain text. It may reference variables using {{name}}:

---
description: Summarize a piece of text in a target word count.
type: prompt
---

Summarize the following text in {{maxWords}} words or fewer:

{{text}}

Body — type: chat

The body is a sequence of role blocks. Each block starts with one of the following labels at column 0, on its own line, immediately followed by ::

• system:
• user:
• assistant:
• developer:

Everything until the next role label belongs to that block. Roles may repeat. Anything before the first role label must be blank.

---
description: Simple Q and A prompt with multiple role blocks.
type: chat
---

system:
You are a helpful assistant. Answer briefly and accurately.

developer:
Keep the answer concise and grounded in the prompt.

user:
{{question}}

assistant:
I can help with that.

user:
Keep the answer short.

Variables

Variables use double curly braces and a simple identifier: {{question}}, {{maxWords}}, {{text}}.

Diagnostics

The extension reports errors directly in the editor for:

• Missing or unterminated --- frontmatter delimiters.
• Frontmatter that is not a YAML mapping or contains YAML syntax errors.
• Unknown frontmatter fields (only description and type are allowed).
• Use of removed fields like name or version, with a message explaining where the value now comes from.
• Missing or invalid type value.
• Chat prompts with no role block, with role labels indented past column 0, or with unknown role labels.
• Non-blank content before the first role label in a chat prompt.

Shared Source Of Truth

The canonical schema lives in src/Zionet.Prompting/Assets/Schemas/prmptmd.schema.json.

Keep editor validation rules in this extension aligned with that shared schema and the prompting library.

Not Included

The extension does not currently provide:

• Completion items or snippets.
• Comments inside the prompt body.

Build And Install

You can package the extension as a .vsix or publish it through the Visual Studio Code Marketplace.

Prerequisites:

• Node.js and npm.
• The VS Code code CLI on your PATH (in VS Code: Shell Command: Install 'code' command in PATH).

From the vscode-extension/prmptmd-vscode folder:

npm install
npm run package
code --install-extension prmptmd-vscode-0.4.0.vsix --force

Then reload VS Code (Developer: Reload Window) and open any .prmpt.md file to verify highlighting and diagnostics.

License

MIT