fullcontext

Stop AI agents from truncating your command output.

A CLI tool that prevents AI coding assistants (Claude, GPT, Copilot, Cursor, etc.) from accidentally hiding critical information when they use head, tail, or grep to limit command output.

The Problem

AI coding agents are incredibly powerful, but they have a frustrating habit: truncating command output.

When an agent runs your test suite or linter, it often tries to be "helpful" by showing only the first or last few lines. This leads to:

• Missing errors - The agent sees 5 of 50 test failures and thinks it fixed the issue
• Endless loops - The agent runs the same command repeatedly, each time seeing different fragments
• Lost context - Critical warnings buried in the middle of output are never seen
• Wasted time - You watch the agent chase ghosts while the real problem scrolls by unseen

If you've ever watched an AI assistant run npm test | head -20 and then confidently declare victory while 47 failing tests scroll past unnoticed, this tool is for you.

The Solution

fullcontext transforms multi-line output into a single line with numbered markers:

# Before: Agent might truncate this
Error: Missing semicolon
  at src/index.ts:10:5
  at src/utils.ts:25:10
Warning: Unused variable 'foo'

# After: Impossible to truncate
[1] Error: Missing semicolon [2]   at src/index.ts:10:5 [3]   at src/utils.ts:25:10 [4] Warning: Unused variable 'foo'

When output is a single line, there's nothing to head or tail. The agent gets everything.

Installation

# Use directly with npx (no install needed)
npx fullcontext npm test

# Or install globally
npm install -g fullcontext

# Or add to your project
npm install --save-dev fullcontext

Usage

Prefix any command with fullcontext:

fullcontext npm test
fullcontext npx eslint src/
fullcontext cargo build
fullcontext pytest
fullcontext go test ./...

In npm scripts

Add it to your package.json for commands you want agents to see in full:

{
  "scripts": {
    "test": "fullcontext jest",
    "lint": "fullcontext 'npm run lint:es && npm run lint:ts'",
    "typecheck": "fullcontext tsc --noEmit",
    "build": "fullcontext npm run compile"
  }
}

For aggregate commands using &&, ||, or |, wrap the entire command in quotes.

Now when an AI agent runs npm test, it gets the complete output every time.

How It Works

1. Runs your command exactly as specified
2. Captures stdout and stderr separately
3. Transforms each into a single line with [N] line markers
4. Preserves the original exit code
5. Preserves all environment variables (AWS credentials, API keys, etc.)

That's it. No configuration, no options, no complexity.

Features

• Zero configuration - Just prefix your command
• Preserves exit codes - CI/CD pipelines work correctly
• Preserves environment - AWS CLI, kubectl, and other tools work seamlessly
• Handles pipes and redirects - fullcontext 'echo "test" | cat' works
• Transforms both stdout and stderr - Nothing escapes
• No dependencies - Pure Node.js

When To Use It

Use fullcontext for:

• Test runners (jest, pytest, go test, cargo test)
• Linters (eslint, prettier, rubocop)
• Type checkers (tsc, mypy, pyright)
• Build tools (webpack, cargo build, go build)
• Any command where missing output causes agent confusion

Don't use fullcontext for:

• Interactive commands
• Commands that output binary data
• Streaming/real-time output (logs, watch modes)

Compatibility

• Node.js: 14.0.0 and above
• Platforms: macOS, Linux, Windows
• AI Tools: Works with any AI coding assistant that executes shell commands

FAQ

Does this affect human developers?

The output is still readable - each line is numbered and separated. But yes, it's optimized for agents. Consider adding it only to specific npm scripts rather than using it for all commands.

Why not just tell the agent not to truncate?

Agents don't always listen. They're optimized to reduce token usage and often truncate output even when instructed not to. fullcontext makes truncation physically impossible.

Does it work with colored output?

Yes. ANSI color codes are preserved exactly as the original command outputs them.

What about very long output?

That's the point! The entire output is returned, no matter how long. If you're worried about overwhelming the agent, consider whether fullcontext is the right tool for that particular command.

License

MIT

Links

• GitHub Repository
• npm Package
• Report Issues

Built for the agentic coding era. Because your AI assistant should see what you see.