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bohrbohr docs

.bohr/preview.json

The preview is your project’s dev server, running in the agent’s sandbox from the homolog branch. .bohr/preview.json says how to start it. The agent writes it when it prepares the repository and keeps it working.

{
  "install": "npm ci",
  "command": "npm run dev -- --host 0.0.0.0 --port 8080",
  "port": 8080,
  "env": {}
}

Fields

Section titled “Fields”
Field Required Description
command Yes The long-running dev server command (up to 1000 characters). Runs with bash -lc in the repository root.
port Yes The port the dev server listens on, 1024 to 65535. Port 4840 is reserved for the bohr agent.
install No Installs dependencies. Runs at the first start and whenever a dependency manifest or lockfile changes.
env No Extra environment variables for install and command. Never secrets: this file is committed.

The commands also get PORT (the port), HOST=0.0.0.0, BROWSER=none and CI=1.

Requirements for the dev server

Section titled “Requirements for the dev server”
  • Listen on 0.0.0.0 (all interfaces) at port. Dev servers that only listen on localhost also work.
  • Accept any Host header. Vite, for example, needs server.allowedHosts: true.
  • Be ready within 3 minutes. Otherwise the preview is marked failed with the end of its output.
  • install must finish within 15 minutes.

When it restarts

Section titled “When it restarts”
  • After every request and every sync, the preview restarts if .bohr/preview.json or the dependencies changed (package.json, lockfiles, requirements*.txt, pyproject.toml, go.mod, Cargo.toml and similar, anywhere in the repository), or if it is not running. Otherwise the dev server’s own reload picks up the change.
  • Stopping kills the whole process group: whatever the command started stops with it.

States

Section titled “States”

The preview goes through these states:

State Meaning
starting Installing or waiting for the port
running The port accepts connections
failed The command exited, or the port did not open in time; the log shows the end of the output
stopped No checkout yet, no .bohr/preview.json, or an invalid one

Messages you may see: “The preview is not set up yet: the agent prepares it when it imports the repository.” (no file yet), and “The preview could not start. Ask the agent to check the file .bohr/preview.json.”

Examples

Section titled “Examples”

A Worker with a D1 database (the templates):

{
  "install": "npm ci",
  "command": "npx wrangler d1 migrations apply DB --local && npx wrangler dev --ip 0.0.0.0 --port 8080",
  "port": 8080
}

Astro:

{ "install": "npm ci", "command": "npx astro dev --host 0.0.0.0 --port 4321", "port": 4321 }