Generative UI... in Python?
Conference Context
- Date/time: 2026-06-30 · 3:20pm-3:40pm
- Track/room: Design Engineering · Track 6
- Speaker(s): Jeremiah Lowin
- Session type/status: session · confirmed
- Track: Design Engineering
- Room: Track 6
- Session type: session
- Status: confirmed
Session Description
MCP Apps are a big deal: tools can now return dashboards, forms, and visualizations directly in the conversation. But somebody (or their agent) has to write those UIs. Fortunately, most of those UIs don't need to be designed from scratch; they can be composed from existing components. In that case, what you really need is a DSL that's token-efficient, streaming-compatible, and has a shallow learning curve. Surprisingly, the best one turns out to be... Python. In this talk, I'll introduce Prefab, a generative UI library that uses Python to compose fully interactive React applications from production components, now natively integrated into FastMCP. I'll demo real use cases, walk through the design, and show where this approach works and where it doesn't. No JavaScript will be harmed.
Media Evidence
Your MCP Server is Bad (and you should feel bad) - Jeremiah Lowin, Prefect (speaker-match related prior/adjacent AI Engineer video; captions: English auto-captions).
- Source video:
youtube-96G7FLab8xc - Slide deck: Dense Slides: Your MCP Server is Bad (and you should feel bad) - Jeremiah Lowin, Prefect — 2 visible slide image(s); 2 HTML recreation(s).
- Additional slide evidence: Slides: Your MCP Server is Bad (and you should feel bad) - Jeremiah Lowin, Prefect, Reconstructed Slides: Your MCP Server is Bad (and you should feel bad) - Jeremiah Lowin, Prefect
- Slide-derived themes for
youtube-96G7FLab8xc: prefect, list, server, should, feel, engineer, code, summit.

Evidence Graph
This evidence graph is generated from currently linked source material: official schedule text, related video pages, cached transcripts, visible slide text, dense/reconstructed slide pages, and AI slide-classification audits.
Media Signals
youtube-96G7FLab8xc— 10 slide-derived text signals- Slide-derived themes for
youtube-96G7FLab8xc: prefect, list, server, should, feel, engineer, code, summit. - Evidence links for
youtube-96G7FLab8xc: youtube 96G7FLab8xc, youtube 96G7FLab8xc slides, youtube 96G7FLab8xc dense slides, youtube 96G7FLab8xc reconstructed slides
Agent Reading Notes
Use these signals to refine the synopsis, topic links, people/company context, and method notes. If a source is a related external video rather than an exact official recording, keep it framed as supporting evidence.
Transcript Status
Related video transcript availability: English auto-captions. Treat this as supporting context, not a recording of this exact scheduled session unless later confirmed. Not fetched yet.
People
Supporting Slides
- youtube 96G7FLab8xc slides — extracted from the related public AI Engineer video.
Slide Evidence
- Slide-only cropped deck: youtube 96G7FLab8xc dense slides (2 viable slide images).
- Related slide/OCR pages:
- youtube 96G7FLab8xc dense slides
- youtube 96G7FLab8xc reconstructed slides
- youtube 96G7FLab8xc slides
- Slide-derived terms:
fastmcp,fivetran,server,prefect,mep.tool,bool,servers,dict,tools,email,user,mcps,product,b1.302,operations,tool,literal,track_latest_order
Synthesis
Synthesized Breakdown
The session explains MCP Apps as a way to add interactive UI to MCP-based workflows. It treats the MCP host as the place where tool data, model reasoning, and human controls meet.
Speaker And Company Context
- Jeremiah Lowin — Founder & CEO at Prefect.
Topics Covered
Derived Links And Source Material
- youtube 96G7FLab8xc — related YouTube source page.
- youtube 96G7FLab8xc slides — slide evidence.
- youtube 96G7FLab8xc reconstructed slides — slide evidence.
- youtube 96G7FLab8xc dense slides — slide evidence.
Novel Concepts / Clever Methods
- MCP Apps As Agentic App Runtime — MCP Apps treats interactive UI returned from MCP servers as a runtime layer for agent-facing software.
Evidence Boundary
This synthesis is based on the official schedule and linked source pages. It should be revisited when exact session recordings or transcript-backed secondary sources are available.