PromptLint VS Code Extension

A VS Code extension that runs the PromptLint CLI to surface diagnostics, quick fixes, and token cost information for LLM prompts directly in your editor.

Features

Real-time diagnostics — squiggly underlines for prompt injection, vague terms, missing structure, politeness bloat, and more
Quick fixes — one-click auto-fix for fixable rules (politeness-bloat, verbosity-redundancy, structure-sections, prompt-injection)
Inline disable — add # promptlint-disable <rule> comments from the lightbulb menu
Token & cost status bar — live token count and cost-per-call in the bottom status bar
Dashboard — view token savings breakdown from the command palette
Magic comment markers — lint prompt regions inside .py, .ts, .js files using # promptlint-start / # promptlint-end

Requirements

Python 3.8+
promptlint-cli installed: pip install promptlint-cli

The extension will prompt you to install the CLI if it is not found.

Supported File Types

File type	Behavior
`.txt`, `.md`, `.prompt`	Entire file is linted
`.py`, `.ts`, `.js`, etc.	Only `promptlint-start` / `promptlint-end` regions are linted

Magic Comment Markers

Wrap prompt strings in code files with markers:

# promptlint-start
SYSTEM_PROMPT = """
You are a helpful assistant that summarizes articles.
"""
# promptlint-end

// promptlint-start
const prompt = `You are a helpful assistant.`;
// promptlint-end

Extension Settings

Setting	Default	Description
`promptlint.pythonPath`	`"python"`	Python interpreter path
`promptlint.lintOnSave`	`true`	Lint when a file is saved
`promptlint.lintOnType`	`false`	Lint as you type (debounced)
`promptlint.lintOnTypeDelay`	`500`	Debounce delay in ms
`promptlint.languages`	`["plaintext","markdown",...]`	VS Code language IDs to activate on
`promptlint.configPath`	`""`	Explicit path to `.promptlintrc`
`promptlint.failLevel`	`"critical"`	Severity threshold (`none`, `warn`, `critical`)
`promptlint.showStatusBar`	`true`	Show token/cost status bar

Commands

Command	Description
`PromptLint: Lint File`	Lint the active file
`PromptLint: Fix File`	Apply all auto-fixes
`PromptLint: Show Dashboard`	Token savings breakdown
`PromptLint: Explain Rule`	Pick a rule and see its explanation
`PromptLint: Initialize Config`	Generate `.promptlintrc` in workspace

Development

cd vscode
npm install
npm run compile

To test locally, press F5 in VS Code to launch the Extension Development Host.