Environment and paths#

The four folders#

Ohm keeps its data in four folders, each of which can be moved:

Folder Holds Default
data settings.json, encrypted credentials, the models folder %APPDATA%\Ohm · ~/Library/Application Support/Ohm
profile Chromium's own state: cookies, cache, local storage, sites you are signed in to the data folder
scripts .ohm files, projects, annotations, the trash <Documents>/Ohm
models downloaded GGUF and ONNX files <data>/models

Each is decided by the first of these that says anything:

command-line flag  →  environment variable  →  config file  →  default
Folder Flag Variable
data --data-dir OHM_DATA_DIR (or the older OHM_USER_DATA)
profile --profile-dir OHM_PROFILE_DIR
scripts --scripts-dir OHM_SCRIPTS_DIR
models --models-dir OHM_MODELS_DIR

A flag takes its value as the next argument or after = or :, and a relative path is resolved against the working directory:

Ohm.exe --data-dir "D:\Ohm\data" --profile-dir=D:\Ohm\profile --scripts-dir ./notes

A throwaway instance that touches nothing of yours is therefore one line:

Ohm.exe --data-dir /tmp/ohm/data --profile-dir /tmp/ohm/profile --scripts-dir /tmp/ohm/scripts

The config file#

For a permanent change there is a config file, editable by hand or from Settings → Folders:

Platform Path
Windows %APPDATA%\Ohm\config.json
macOS ~/Library/Application Support/Ohm/config.json
Linux $XDG_CONFIG_HOME/ohm/config.json (else ~/.config/ohm/config.json) 
{
  "version": 1,
  "dataDir": "D:\\Ohm\\data",
  "profileDir": "D:\\Ohm\\profile",
  "scriptsDir": "D:\\Ohm\\scripts",
  "modelsDir": "E:\\models"
}

It deliberately does not live in the data folder — it is what says where the data folder is — so it stays put in the system's standard config location whatever else moves. Keys it does not recognise are left alone when Ohm writes to it, and a file it cannot parse is ignored with a warning rather than stopping the app.

Two things worth knowing:

  • Changes apply at the next start. Chromium holds its profile open for the life of the process, and settings are already loaded, so Ohm never switches folders mid-run. Settings → Folders shows what is running now and what is queued, with a Restart now button.
  • Nothing is moved for you. Pointing at a new folder starts from whatever is in it — an empty one gets a fresh setup, and the scripts folder is seeded with the examples. Copy the old contents across yourself if you want them.

Other environment variables#

All optional, read once at startup in apps/desktop/src/main.ts.

Variable Default Effect
OHM_UI_URL ohm-app://ui/index.html Load the renderer from a dev server instead of the packaged files. npm run dev sets this.
OHM_DEVTOOLS unset With OHM_UI_URL, opens DevTools for the UI on start.

Electron's own flags still work, which is what makes the app testable from the outside:

Ohm.exe --remote-debugging-port=9333

Paths#

What Windows macOS
Scripts and projects %USERPROFILE%\Documents\Ohm ~/Documents/Ohm
Settings, credentials, models %APPDATA%\Ohm ~/Library/Application Support/Ohm
Browser profile (cookies, cache) %APPDATA%\Ohm ~/Library/Application Support/Ohm
Folder config %APPDATA%\Ohm\config.json ~/Library/Application Support/Ohm/config.json
Installed program (per user) %LOCALAPPDATA%\Programs\Ohm /Applications/Ohm.app

Uninstalling removes the program and, if you say yes, the default settings folder. The scripts folder is never touched by an uninstall, and neither is a data or profile folder you moved elsewhere — delete those yourself if you want them gone.

Custom URL schemes#

Three privileged schemes are registered before the app is ready. They are internal, but they show up in DevTools and in the CSP, so they are worth knowing:

Scheme Serves Root
ohm-app:// the renderer (HTML, JS, wasm) apps/ui/dist (or ui/dist in a packaged build)
ohm-models:// local model weights the models folder
ohm-file:// a project's documents, read-only the scripts folder

Each handler resolves the request against its root and refuses anything that escapes it.