# Branch per task

A preview environment is a copy of production (sanitized by default) with its
own URL, keys and database, and a time to live. An agent can migrate, seed
and break it freely; production only changes when you approve a merge.

## The loop

```sh
TASK=add-invoices
scribase env create acme my-app "pr-$TASK" preview sanitized aws-eu-central-1 "create-pr-$TASK" 24
scribase operation get acme <operation-id>                 # until succeeded
scribase branch register acme my-app "pr-$TASK" --base production
scribase apps switch acme my-app --env "pr-$TASK" --format dotenv > .env.preview

scribase migrate acme my-app "pr-$TASK" --dir supabase/migrations --apply
scribase gen types acme my-app "pr-$TASK" --out src/database.types.ts

scribase branch diff  acme my-app production "pr-$TASK"
scribase branch merge acme my-app production "pr-$TASK" --dry-run
```

The agent shows you the diff and the dry run. After you approve:

```sh
scribase backup create acme my-app production "pre-$TASK"
scribase branch merge  acme my-app production "pr-$TASK"
scribase env delete    acme my-app "pr-$TASK" "delete-pr-$TASK"
```

Over MCP the same steps are `environment.create`, `operation.get`,
`branch.register`, `migrate.run`, `branch.diff`, `branch.merge`,
`backup.create` and `environment.delete`. The `scribase-safe-change` skill
walks an agent through this loop, including the RLS proof with
`policy.test`.

## Data modes

| Mode | What the preview gets |
|---|---|
| `sanitized` | A copy of the parent's data, then anonymized. The default for previews. |
| `snapshot` | An exact copy. Only when you ask for real data. |
| `schema_only` | Schema, no rows. |

## Pull requests

Link the preview to its pull request so each shows the other:

```sh
scribase branch pr acme my-app "pr-$TASK" github acme/app 42
```

A preview is removed automatically when its TTL expires. Extend it with
`scribase env renew acme my-app "pr-$TASK" 24 "renew-pr-$TASK"`.

See [Branching](https://docs.scribase.com/docs/concepts/branching.md) for how branches work underneath.