Quickstart, try the demo

For anyone who wants to see the tool working. Tutorial.

In this tutorial you run Changeset Second Opinion on your own computer, in replay mode. When you finish, you will have a queue of fifteen real changesets open in your browser, and you will have opened one of them.

Replay mode is safe to try. It serves saved changesets, so nothing is fetched from OpenStreetMap and nothing is posted to it. The tool never writes to OpenStreetMap in any mode, and lanes only order the queue: nothing is hidden, nothing closes by itself and nothing is posted by itself.

What you need

• Python 3.13
• uv, the Python package manager
• A recent version of Node.js
• Two terminal windows

You do not need a GPU, an AWS account or a network connection to OpenStreetMap.

Start the backend

In the first terminal, go to the backend folder of the repository and install the dependencies.

cd backend
uv sync --frozen

Create the database and load the demo set. The first command makes a cso.db file in the backend folder. The second loads fifteen real changesets, each with a saved reading from the Decider.

uv run cso db upgrade
uv run cso seed

The seed command prints how many cases it created, for example seeded 15 new and 0 existing cases. Running it again is safe. It counts the cases that are already there and does not add them twice.

Make an invite code so that you can sign in as a reviewer. The code is printed once and is not stored, so copy it now.

uv run cso auth create-invite --role reviewer --ttl-hours 24

Start the API. It listens on http://127.0.0.1:8000. Leave it running.

uv run cso api

Start the web app

In the second terminal, go to the web folder, install the packages and start the dev server.

cd web
npm ci
npm run dev

Open http://127.0.0.1:5173 in your browser. The dev server passes requests for /api on to the backend on port 8000, so both terminals need to stay open.

Look around

You land on the home page. Choose Open the queue. You can browse as a viewer without signing in.

To act on cases, go to the sign-in page, enter your invite code and a display name, and choose Sign in. The display name is shown next to the decisions you record.

The queue shows fifteen cases. A blue banner at the top says Demo and repeats that nothing is fetched live and nothing is posted to OpenStreetMap.

The queue on the demo data. Newest first inside each lane, and every case stays in the list.

What you are looking at:

• The lanes along the top and in the side bar. They order the queue. In the screenshot, 4 cases are in Review suggested, 4 in Needs local knowledge and 7 in Insufficient evidence.
• Each row shows the changeset number, the editor, the place, what the mapper said in the comment, how many elements were created, modified and deleted, and a band that says how decisive the model was.
• The band describes how clear the model’s answers were. It is not a chance that an edit is harmful.

Open any row. The case page shows the evidence on the left and the suggested response on the right. The fact panel lists ten questions, and each one has a reading and a probability.

A case. Evidence on the left, recommendation on the right, actions along the bottom.

Where to go next

Work through review your first changeset. It walks one demo case from the queue to a recorded decision.

If something goes wrong

• The queue says “No cases yet”. The database is empty. Run uv run cso seed from the backend folder, then reload the page.
• “Could not reach the server”. The API is not running, or it is not on port 8000. Start it again with uv run cso api from the backend folder.
• “That invite code was not accepted”. The code is wrong, has expired (this one lasts 24 hours) or was revoked. Make a new one with uv run cso auth create-invite --role reviewer --ttl-hours 24.
• “Too many attempts”. Sign-in attempts are rate limited. Wait for the number of seconds the message gives and try again.
• A button says to sign in as a reviewer. You are browsing as a viewer. Viewers can read every case. Reviewers can analyze again, write drafts and record decisions.
• The commands fail before they start. Check that Python 3.13, uv and Node.js are installed.