tango

# Setup

## Configuration

```elixir
# config/config.exs
config :tango,
  repo: MyApp.Repo,
  schema_prefix: "tango", # Optional
  encryption_key: System.get_env("TANGO_ENCRYPTION_KEY"),
  api_key: System.get_env("TANGO_API_KEY")
```

Generate an encryption key:

```bash
openssl rand -base64 32
```

For browser popup completion (0.2.0+), also configure exact origins — see
[AUTHORIZATION.md](AUTHORIZATION.md#exact-origin-setup).

## Migrations

`mix tango.setup` writes a wrapper migration to `priv/repo/migrations/`;
`mix ecto.migrate` applies it.

```bash
mix tango.setup
mix ecto.migrate
```

`mix tango.setup` is for the **initial install only** — its generated `down`
calls `Tango.Migration.down()`, which targets version 0 and drops every Tango
table. Never rerun it to pick up a new schema version.

### Upgrading an existing install

When a Tango release ships a new schema version, write a fresh migration in
your application pinning the version range explicitly, so rolling it back
returns to the previous version instead of dropping the schema.

**Tango 0.2.0 ships schema version 3 (V03).** It adds the
`tango_authorizations` table for authorization candidates, binding columns on
`tango_oauth_sessions` (completion origin, intent reference, expected
connection and subject, authorization parameters, OAuth client), and
`account_subject` / `oauth_client_id` on `tango_connections`. Upgrading from
0.1.x:

```elixir
defmodule MyApp.Repo.Migrations.UpgradeTangoV03 do
  use Ecto.Migration

  def up, do: Tango.Migration.up(version: 3)
  def down, do: Tango.Migration.down(version: 2)
end
```

Run `mix ecto.migrate` before deploying code that uses authorization completion.

### Without Ecto migrations

Copy the SQL from `priv/repo/sql/versions/<version>/` into your migration tool
of choice (replace the `$SCHEMA$` placeholder with `"public"` or your custom
prefix), and stamp the version marker EctoEvolver would have written, so
`Tango.Migration.migrated_version/1` agrees with the physical schema:

```sql
COMMENT ON TABLE "$SCHEMA$".tango_providers IS 'Tango version=3';
```