# Change one contract across three repos
> Create one feature, promote api, web and shared-types, plan once, and preview one pull request per repo.
Source: https://ivar.run/docs/recipes/one-feature-three-repos

You need a hall with `api`, `web`, `shared-types` and `infra`, and a harness you can launch from it. The change: add an `avatarUrl` field to the user profile, return it from the API and render it on the web profile page.

```sh
ivar feature create avatar-url
ivar feature promote avatar-url api
ivar feature promote avatar-url web
ivar feature promote avatar-url shared-types
ivar session start avatar-url
```

In the session, run `/ivar-plan` and approve each gate. Then, from the hall:

```sh
ivar feature deliver avatar-url --preview
```

## What happens

- `feature create` names the branch once. No repo carries it yet.
- Each `feature promote` puts a worktree on the `avatar-url` branch in that repo. `shared-types` describes the field in `user.ts`, `api` returns it and `web` shows it.
- `infra` is not promoted, so it stays read-only on its default branch and the agent cannot commit there.
- `/ivar-plan` writes one plan for the three repos. `deliver --preview` refuses to run until the plan gate is approved.
- The preview prints a summary and a fingerprint and pushes nothing. It lists three pull requests: `api`, `web` and `shared-types`. `infra` gets none.

To see where the feature stands before you deliver, run `ivar feature status avatar-url`. It lists every promoted repo and its state. If a repo needs another change later, promote it onto the same branch with `ivar feature promote avatar-url <repo>`. Nothing already in the feature moves.

The plan is the point of the order. `/ivar-plan` runs requirements, analysis and plan with an approval gate after each, so the agent writes code against one agreed contract in `shared-types` instead of three guesses. Delivery then pushes three branches that share a name and opens three pull requests that link to each other.

## Read the full walkthrough

[One feature across multiple repos](/blog/one-feature-across-multiple-repos) covers the same flow with the preview output and the sibling-PRs comment. For the commands, see [features](/docs/guide/features) and [delivery](/docs/guide/delivery).