Prompts side by side, each on its own branch
· Nicrron Engineering
In Ninoo Builder, several people can now prompt the same project at once. Each prompt after the first runs on its own git branch with its own live preview, and finished branches merge back into the live app, with the model combining changes that touch the same lines.
The problem
A Builder project used to run one prompt at a time. Every layer assumed it: the project lock, the transcript, undo, the single dev server. When two people worked on the same app, the second person's prompt waited in their tab until the first one finished.
How it works
The first prompt runs on main, in the live workspace, exactly as before. A prompt sent while another is running gets a git worktree of its own, made from main's latest commit, and the agent works there. A project runs up to three prompts at once, one per person, and the workspace is given more memory and CPU while more than one is running.
Each branch can have its own live preview on a separate port, so you can look at a change before it reaches the app. When a branch finishes, it joins a merge queue that merges it into main under the project lock.
If both changes touched the same lines, a short model turn resolves the clash inside the branch, keeping the intent of both changes, and the merge is tried again. If that still fails, the branch waits with Try again and Discard, and nothing reaches the live app half-merged.
What surprised us
- 01Vite refuses to serve files from anywhere under a .git directory, so the branch copies had to move out of the history repository to a directory of their own before branch previews would load.
- 02A clash can appear at the last moment, when main moves while a branch is being merged. It became a state of its own that the merge queue always resolves, rather than an error.