A digital field book by Joost van der Zwan
Designing Software Behavior in the Age of AI
Learn to specify what an AI-assisted product notices, suggests, acts on, explains, remembers, and hands back.
One framework from the book
Negotiated Software Loop
Describes the new contract between user and machine in probabilistic systems: intent, interpretation, suggestion, review, correction, adaptation.
- Observed
- Interpretation
- Proposal
- Human decision
- Completed
What the screen hides
Interface
Copy, layout, buttons, forms, feedback, and the visible promise of the product.
What changed, and what stays true now?
What should the product remember or forget?
Who can act, see, approve, or override?
When should the system interrupt, wait, or hand back?
How certain is the system before it acts?
Which tools, people, and steps are coordinated?
What happens when the system is wrong?
What must be explained instead of hidden?
The book teaches you to design the behavioral system behind the interface.
One behavior
An invoice can look clean before the product has earned that claim.
The extracted fields look plausible. The purchase order names a different supplier. New bank details cross company policy. The product still has to decide whether to prepare, route, hold back, or act.
The short experiment separates evidence quality, measured reliability, permission, consequence, and recovery—the decisions a polished summary can hide.
Inspect the invoice review experimentThe reader mirror
This is for the builder who reads the system through the screen.
You can see the product decision inside a workflow before anyone names it.
You care about what the system should notice, remember, refuse, and recover from.
You care about the screen because it reveals what the system permits.
The arc
Six stages. Fourteen chapters. A path the reader earns one stage at a time.
The book is built as an emotional arc, not a flat list. Each stage earns the next. Land in the stage you’re standing in, or read from recognition through commitment.
Framework previews
The book becomes useful when its ideas become instruments.
- layered-stackThe Product Beneath the InterfaceThe book's defining lens. Names the system layers that shape what the visible UI can honestly express.
- loopNegotiated Software LoopDescribes the new contract between user and machine in probabilistic systems: intent, interpretation, suggestion, review, correction, adaptation.
- listBehavior Design QuestionsA working list of questions to ask when designing behavior rather than interaction.
- layered-stackThe Trust StackNames the structural materials of trust in intelligent systems, from expressive at the top to foundational at the bottom.
- canvasWorkflow Authorship CanvasA canvas for redesigning a workflow rather than wrapping it in better UI.
- listAuthorship PracticeThe six commitments that constitute the practice of product authorship over time: standards, point of view, taste, responsibility, consistency, reflection.
The journey
A complete reading path, with a private record of what changes as you move through it.
Read linearly when you want the full argument. Return through the Workbook for the reflections you have saved. Carry the Field Kit when the work moves outside the chapter.
Author and practice
The work connects product judgment to the system a team can build.
If you are shaping workflow-heavy B2B software and the hard question is how the product should behave, write to Joost or inspect the evidence behind this project.