What the product keeps, and who acts on it
- Order
- Customer
- Payment provider
Open source
Product-Driven Development for coding agents
Your AI agent is guessing what the product is. PDD gives agents and humans a shared product model that is git-tracked, reviewable, and verifiable.
npx pdd-toolkit install
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Product Model
One definition of what your product does.
How people and systems reach the product
- Web app
- Mobile app
- Partner API
The subject areas the product is split into
- Ordering
- Catalog
- Billing
What the product lets someone do
- Check out
- Cancel order
- Refund
One goal, carried across several capabilities
- Browse and buy
- Sign up
- Reorder
What must always hold, and who may do what
- Max 3 per order
- Only managers refund
- Total includes tax
Where the product works in more than one way
- Feature flag
- Plan tier
- A/B test
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Where is your product model today?
It already exists, just unstructured, incomplete and scattered across docs, code, tickets, chats and people.
Written before the work, never corrected after
It shipped differently, and nobody went back
Accurate on the day it was written
Where the decisions were really made, and lost
Flows and screens the build moved on from
Shows what it does, never what it must do
Say what is, not what must be
People
Leave when they leave
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Clear product model. Focused sources.
Bring knowledge from docs, designs, code, and people into one product model. Fill gaps, clarify uncertainty, and make every source leaner and more focused.
| Source | Focus |
|---|---|
| User docs | Teaches people to use the product |
| Internal docs | Records architecture, design decisions, and onboarding |
| Design & architecture | Describes how it should look and work |
| Code & tests | Implements and verifies how it is built |
| Tickets, chats & people | Carry context, requests, and undocumented knowledge |
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What changes with a product model.
One shared definition guides the work and stays current as the product changes.
Without a product model
With a product model
- Definition
Without a product model
Spread across many places
Tickets, docs, chats, code and people each hold a piece.
With a product model
Written in one product model
It lives beside the code and links back to those sources.
- Agents
Without a product model
Work out what you meant
They infer behavior and rules from whatever they can find.
With a product model
Know what to build
They get journeys, scenarios and rules before they start.
- Done
Without a product model
The code is finished
It can work correctly and still miss product intent.
With a product model
The code matches the product
Approved scenarios make the expected behavior clear.
- Drift
Without a product model
Found when someone notices
Old docs can look correct long after behavior changes.
With a product model
Differences are easier to find
The model provides a clear reference as behavior changes.
- Decisions
Without a product model
Often live outside the code
The reason is left in a ticket, document or conversation.
With a product model
Travel with the code
Model and code updates are reviewed together in the PR.
- After ship
Without a product model
The request becomes history
Tickets and specs explain changes, not today's product.
With a product model
The model stays current
Approved behavior remains part of the product definition.
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One loop, run on every change.
Ideate and verify with pdd-kit. Your own agent implements, your way.
Ideate
/pdd-ideateDecide the next change and record it in the product model.
Implement
your agent, your way
In phases, with plan mode, an SDD tool, or freestyle.
Verify
/pdd-verifyCheck and improve the code and product model until they agree.
Back to Ideate. The next change starts here.
AI agents and humans need a living product model.
pdd-kit is open source and MIT licensed.
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