The cognitive stack: what comes after building AI platforms

BWI Architecture Summit 2026 · Nuremberg, Germany · April 21, 2026

Opening-day talk at BWI's annual architecture summit. BWI GmbH is the IT service provider for the German Armed Forces (Bundeswehr). ~150 architects, deeply technical, security-conscious government IT background. 20 minutes + Q&A.

Slides

Download slides (PDF)

Key frameworks

• The cognitive stack
• The invisible 80%
• The bitter lesson of workplace AI

The talk

Most knowledge work is invisible: thinking, reasoning, judgment. The visible outputs (emails, documents, chats) are artifacts, not the work itself. Enterprise AI targets only the visible 20%, which is why the ROI numbers disappoint.

The cognitive stack maps how AI actually impacts knowledge work: worker → cognitive extension (second brain) → skills & frameworks → AI agents → interfaces. The invisible 80% lives in the top three layers. Enterprise AI investment concentrates at the bottom two.

The subtitle "What Comes After Building AI Platforms" speaks directly to BWI's world: the platform is necessary but not sufficient. What matters is the cognitive layer on top.

Key arguments

• Second brains as cognitive extensions: Point AI at files on your computer, let it maintain your context. "Within two hours, I realized I'm never going back."
• Skills over automations: "If you have a task that can be automated, you are a task worker." The cognitive stack works because you don't have to think like a programmer.
• Token economics: Six ways to do the same Excel task, ranging from 200K tokens to zero. Someone has to route those decisions across thousands of workers, hundreds of times a day.
• AI trust: "AI is not software. You have to think of it as a colleague." Apply the same guardrails as humans: logging, limited permissions, dedicated identity.