# Ground Fail Fast

> Fail-fast patterns. Reject invalid input at the boundary.

- Skill: `attac-t/ground-fail-fast` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add attac-t/ground-fail-fast`
- Raw SKILL.md: https://api.skillmd.com/api/skills/attac-t/ground-fail-fast/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: attac-t (https://skillmd.com/u/attac-t)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/attac-t/ground-fail-fast

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# Skill: Fail Fast

> "Reject invalid input at the boundary. Don't let it travel through the system."

## The Standard

- **Boundaries are gates**: HTTP request enters? Validate. Job payload arrives? Validate. Once past the gate, trust the data.
- **Actions trust input**: If you're validating inside an action, validation happened in the wrong place.
- **Fail loudly**: Invalid state should throw, not return false. Silent failures hide bugs.

## The Check

Ask yourself:
- Where does invalid data first enter this flow?
- Is validation happening at that boundary?
- Are downstream components trusting validated input?

## Real-World Examples

See [examples.md](examples.md).