---
title: Hands-on: Prompt vs Spec
collection: Spec Driven Development for AI Apps
author: Anirudh Jwala
updated: 2026-10-21
source: https://docs.chaicode.com/sdd/hands-on
---

# Hands-on: Prompt vs Spec

## Prompt vs **Spec**

Prompt vs **Spec**
Same feature. Two workflows. One set of acceptance tests.

## Reliable bookings, plus **cancellation**

Problem statement
Reliable bookings, plus **cancellation**
No overbooking: No event is ever booked past capacity
One per student: One booking per student per event
Cancel frees: Cancelling gives the seat back

## Two users. **One seat**. Both bookings succeed.

The race condition
Two users. **One seat**. Both bookings succeed.
Disabling the button in React is UX, not enforcement.

## What is **OpenSpec**?

Round 2 tooling
What is **OpenSpec**?
An open-source, lightweight SDD workflow for the coding agent you already use.
Not a framework: Not a framework, language, or agent
Lives in your repo: Adds slash commands and a folder of Markdown specs
For existing apps: Built for changing existing apps, one change at a time

## The OpenSpec **workflow**

Round 2
The OpenSpec **workflow**
Explore: inspect the current flow
Propose: draft proposal, specs, design, tasks
Human review before any code
Apply: the agent works the task list
Verify, then archive into living specs
Gaps found? Revisit the relevant step

## Investigate first, then **plan** the change

Explore and propose
Investigate first, then **plan** the change

## Rules we **agree** on before code

Review the spec
Rules we **agree** on before code
Signed-in only: Anonymous users cannot book
One active booking: Per student, per event
Never over capacity: Even with concurrent requests
Cancel only your own: No cancelling another student's booking
Cancel frees the seat: The seat returns to the pool
Cancelled events reject: No bookings on a cancelled event

## Pin down the **behavior**, let tests judge

Takeaway
Pin down the **behavior**, let tests judge
A spec defines expected behavior. Independent tests help us verify what actually got built.