A code editor built
for the AI agent era.
Color-coded UI — see at a glance which AI is running, and which one you are talking to
Bring your own AI agent — your existing subscription works as-is over ACP, the open agent protocol
Native performance — no Electron. Rust + GPUI, low memory and 60fps
Multiplexer — Fleet mode, a new idea for the agent era
Color tells you where you are
The color you assign to a project carries all the way through — the rail, the tabs, the caret, the AI threads. However many projects you run side by side, you never lose track of where you are.
Try it — project color
Your own AI agents, running as they are
Claude Code, Codex and any other ACP-compatible agent work out of the box. They run on the subscription you already have — no extra API key.
and other ACP-compatible agents
The destination, always shown — you can always see which thread and which branch you are sending to
Token usage, always shown — per-thread consumption and the running total, always in view
Diff review and checkpoints — review the changes before taking them in, and roll back whenever you want
Todo board — tasks live in a Markdown file, and the agent ticks off what it finishes
Native speed in every interaction
Written in Rust and drawn straight on the GPU by GPUI. No Electron, no webview — launch, scrolling and typing all stay light.
215ms
launch → ready to type
cold start
122MB
idle memory
RSS right after launch
10ms
⌘P filtering
measured over 50,000 files
60fps
drawn on the GPU
GPUI native UI
Measured on an M1 Mac
Fleet mode — a multiplexer for agents
Run several agents side by side on one screen, and direct them while watching the whole picture. Each agent is isolated in its own worktree, so they can work on the same repository at once, safely.
Every cell is live
The cells are not shrunken previews — they are the running agents and terminals themselves. Work in them directly, or maximize one to focus on a single agent.
Everything you expect from an editor
LSP · tree-sitter · Git · terminal · Remote SSH · IME · hot exit
The person building it
Daichi Nagashima — physician · AI engineer · CEO of GENSHI AI
I got my medical license in 2022 and met generative AI while working as a resident in Beppu, Oita. A year later I left residency to build AI full time. Today I hold a research post in cardiology at the University of Tokyo Hospital and run GENSHI AI as its CEO — training image, speech and language models, shipping them as products, and carrying them all the way to the clinic myself.
My main product is MedLocal — a medical LLM that lives inside the hospital. Discharge summary drafts, ambient voice charting in the clinic and OCR for referral letters, all running on machines inside the building so patient data never leaves it. In September 2026, an ITmedia feature on on-premise LLMs in Japanese clinics interviewed me as CEO of GENSHI AI.
necoder came out of those days. Once several agents are running at once, you lose track of which AI is working on which project, on which branch. The color-coded UI, the destination chip and Fleet all started from that pain. necoder is developed inside necoder: I use it every day and fix whatever trips me up, on the spot. That is the only way features get chosen.
Solving a problem I felt in the exam room with code I wrote myself. That short distance is what makes my work worth something.
Other things I have built
Meet nyaco
The cat-eared coder who lives at the top right of the Agent panel. Her gestures tell you what the thread is doing.
