Manz, a founding engineer at Marimo, argues that data work can get the same long, self-correcting agent loops that software development already has. That requires a notebook that exposes its live state to an agent through a skill. Marimo pair does this, leaving a reproducible, auditable notebook rather than logs, and Manz traces it to a career spent making visualization and interactivity as easy to use as a Python import.
Why a reactive notebook. Manz calls Marimo a "delightful reactive Python notebook". It understands relationships between cells, re-runs stale ones and guarantees the document reflects the true state. That removes the habit, which the host describes, of constantly restarting Jupyter notebooks to be safe. Marimo is MIT-licensed and was acquired by CoreWeave last fall. Manz says CoreWeave's direction is to grow the open source, with Marimo pair and a VS Code extension, and to make Marimo the open standard for Python notebooks.
Making agents useful in notebooks. Manz defines an agent as a model plus tools in a loop. Coding agents handle files and commands but couldn't see data loaded into memory, so notebook users babysat them by pasting errors back. Marimo pair is a skill (a folder of markdown files) that teaches an agent to start or connect to Marimo and run Python in its runtime. It can then ask about anything the user sees, read cells and screenshot them. Manz now starts data tasks in Claude Code, describes datasets and libraries declaratively, and edits cells by hand alongside the agent. Agents also make exploration cheap: he can ask for validations he would otherwise skip.
Skills as a new kind of contract. Instead of fixed APIs, the agent discovers tools hidden in Marimo. API changes between releases don't break it, and upgrades just add capabilities. Manz says he came to skills late, around November with Claude Opus 4.5 (he first said 4.6, and the host corrected him). His first skill was imperative and models followed it too rigidly at exceptions, so he made it declarative. That means teaching the tools and nuance and letting the model decide how. He likens the shift to prompting losing importance as agents fetch context on demand. If he repeats himself to an agent, that belongs in a skill, and failures mean updating the skill.
Recursive language models. Manz says coding agents are already a form of the recursive language models described in research released last year. These offload context to an environment, usually the file system, to avoid context rot. Marimo pair adds in-memory Python values to that environment. The notebook's cells become a consistent scaffold of the agent's memory, unlike the ten different file-system routes an agent might take to the same question.
AnyWidget and lowering overhead. At Harvard Medical School's HIDIVE lab, Manz worked on open-source tools including Viv, Quak and Zarr.js. He found that persuading researchers to adopt a new visualization app was the hard part. His AnyWidget is a standard and implementation for bidirectional Python-to-web widgets across Jupyter, Colab and Marimo, and it is how Marimo found him. In a SciPy talk he likened widgets to catalysts that lower the activation energy of reaching insight, since visualization tools usually need an app download and data export. In Marimo, a widget selection becomes a variable that reactively drives downstream cells, so an outlier can be clicked rather than filtered with a typed predicate. His progressive design lets a widget start as plain JavaScript in a notebook and move to a library, adding TypeScript and type checks as the code grows. He says that discipline matters more now that so much code is generated.
Visualization first, and going deep. Manz checks data visually at every pipeline step, having lost afternoons to missing values a glance would have caught. He argues that abstract biological data need purpose-built views such as the genome browser, close to where the analysis happens. He says he now actively resists answer-on-demand tools so he can keep going deep on topics, which he expects to stay valuable.