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Software Behaviorby Joost van der Zwan
Index

Field notes · 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.
Begin readingTry an example

Progress stays in this browser.

A finger reaches for a phone showing a half-filled progress bar, between a pencil and a stopwatch on graph paper.

Fig. 0 · One response, timed

TPA · Home

01 · One framework from the book

Negotiated Software Loop

Fig. 1 · One pass through the loop

  1. Intent (Person): The user arrives with a goal, often only partially specified; the product treats it as intention, not always as complete instruction.
  2. Interpretation (System): The system forms a working understanding from the request, context, defaults, history, and available data.
  3. Suggestion (System): The system proposes an output, action, classification, draft, or next step, framed according to confidence and stakes.
  4. Review (Person): The user evaluates whether the suggestion fits the goal, context, and consequences.
  5. Delegation (Person): The user hands the system bounded work to carry out: what it may touch, how far it may go, and when it must stop and ask. Optional; when it happens, the grant is as legible as the suggestion.
  6. Report back (System): The system returns an account of what it did, skipped, assumed, and could not undo; for delegated work, the report is the review surface.
  7. Correction (Person): The user edits, rejects, redirects, accepts, or clarifies what the system produced.
  8. Adaptation (System): The system changes what it does next based on the correction; the change may be temporary, durable, or global.

Each correction changes the next interpretation. Circles are your decisions; squares are what the system does.

Describes the new contract between user and machine in probabilistic systems: intent, interpretation, suggestion, review, delegation, report back, correction, adaptation.

Open the framework

The Product Architect · Frameworks

Fig. 1 · 4 / 15

02 · The arc

Six stages. Fifteen chapters.

A path you earn 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.
Read the manifesto
  1. TPA-I · 1 / 6
    Recognition

    Naming what you're already feeling.

    2 chapters
  2. TPA-II · 2 / 6
    Reframing

    A new lens for what software is now.

    2 chapters
  3. TPA-III · 3 / 6
    Excitement

    What becomes possible from inside the new lens.

    2 chapters
  4. TPA-IV · 4 / 6
    Seriousness

    What this craft now demands of you.

    5 chapters
  5. TPA-V · 5 / 6
    Agency

    Acts you can run this week.

    3 chapters
  6. TPA-VI · 6 / 6
    Commitment

    Standing for the new role.

    1 chapter
15
Chapters
15
Frameworks
—
Frameworks practiced
6
Stages
—
Read on this device

Swipe for all six stages

The Product Architect · Contents

Stages I–VI · — / 15

03 · 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.

Fig. 2 · INV-20418

New bank details cross company policy. The product still has to decide.

Inspect the invoice review experiment

The Product Architect · Case

Fig. 2 · Invoice review

04 · 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.

Interfaces show. Behavior decides. I design how software behaves.

Joost van der Zwan
Write to JoostAbout the work

Field notes on Instagram: Studio JZ • Design, Behavior & Science.

Follow on Instagram
Joost van der Zwan, photographed against a painted brick wall.

This is for the builder who reads the system through the screen.

  1. 01

    You can see the product decision inside a workflow before anyone names it.

  2. 02

    You care about what the system should notice, remember, refuse, and recover from.

  3. 03

    You care about the screen because it reveals what the system permits.

Newsletter · monthly

One Field Note a month.

What changed in the book, the latest episodes, one framework in practice.

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