Startups · Cosma
Founder · Brand and product collective · Jun 2025 to Present · Madison, WI
Cosma is the brand. Under it, we are trying to rethink how people interact with their files in a world where the traditional Unix file and disk model is starting to feel ancient. The products we ship are all attempts at the same question: what should the modern file system actually look like?
The way most of us handle files has not really changed since the 70s. Folders, names, paths, directories, drag and drop. It made sense when disks were small and expensive and you had to know exactly where every byte lived. It makes much less sense now, when most of what we own is a giant sea of PDFs, screenshots, notes, code, emails, and random downloads that we vaguely remember saving somewhere.
Our bet is that the modern file interaction layer should:
Everything we build under the Cosma brand is an experiment aimed at some part of that stack.
We did not land on the final product on the first try. We tried four distinct things in sequence, and what we learned from each one shaped the next.
1. AI file organizer
The original idea: an agent that watches your Downloads folder and sorts things into a semantically meaningful structure automatically. We got it working. The problem was trust. People do not like autonomous agents moving their files around, even when the moves are correct. The UX of "I put your stuff somewhere, go find it" did not land.
2. AI folder icon generator tool
Next we tried focusing on the visual layer: an app that looks at what is inside a folder and generates a custom icon that fits. This turned out to be a great product, but it was a completely different thing from file organization. We decided it deserved to stand on its own, so we spun it out as Foldi, which is now its own project in Software Projects.
3. Local file RAG
After Foldi split off, we went deeper on retrieval. We built a local first RAG system over the user's entire file collection. This was the one that actually clicked. The semantic search experience felt like what "Finder" should have been in 2025.
4. Cosmasense
The local RAG experiment grew into Cosmasense, our current main product: a local first, AI powered semantic search engine that indexes your files and lets you find things by describing what you are looking for, not by remembering exact filenames.
Cosmasense is a four stage pipeline:
The backend is published on PyPI as cosma — installable with one line via uvx.sh/cosma/install.sh. Runs as a persistent background process (cosma serve) that watches directories, parses new files, and serves search queries.
CLI, with three output modes for different consumers:
--plain — simple text output for piping into shell scripts--json — structured JSON output for agents and programmatic accesscosma search "my query" # Search indexed files
cosma index /path/to/dir # Index a directory
cosma status # Check backend status
cosma watch add /path/to/dir # Watch directory for changes
cosma files stats # File statisticsTUI — full terminal UI via cosma tui /path. Native macOS app sits on top of the same backend for the Finder-replacement experience.
Tested on macOS ARM and Windows; Linux support in progress. All three surfaces (CLI, TUI, macOS app) share the same PyPI backend.
Cosma came out of a UW Madison program in collaboration with OpenAI. I am the founder, driving the product side and also running an academic benchmarking study on how well LLMs can reason about file organization. We plan to publish those results. Part of the UW Madison SAIL and NYU Leslie eLab cohorts.
NYU Startup Accelerator Program — Certificate of Completion for Cosmasense.
https://www.linkedin.com/posts/ethan-pyy_first-journey-activity-7437152419190394880-PYAtThis is the plain-HTML mirror served to crawlers, LLMs, and curl. Humans with a JavaScript-enabled browser see the rich React/XP-themed SPA at the same URL.