> ## Documentation Index
> Fetch the complete documentation index at: https://docs.junction.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Fast Launch

> Use Fast Launch URLs to reduce repeated App Embed launch latency when a compatible Junction session already exists.

<Card horizontal icon="person-digging" color="#57164A">
  Interested in this feature? Get in touch with your Customer Success Manager.
</Card>

Fast Launch lets your client-side application open a Junction feature without first asking your backend to create a dashboard URL. When Junction detects an existing compatible session, it routes directly to the requested feature. If it cannot reuse a session, it redirects to your [session continuation URL](/app-embed/session-continuation), where your application creates a new dashboard URL.

Use Fast Launch when:

* you embed Junction features in iframes; and
* users often move between parts of your app that embed different Junction features.

## Fast Launch URL

Use your partner integration slug as the subdomain.

```text theme={null}
https://{integration_slug}.ehr.junction.com/auth/launch
```

You can identify the target member and team with either partner references or Junction IDs.

<CodeGroup>
  ```text Partner references theme={null}
  https://{integration_slug}.ehr.junction.com/auth/launch
    ?integration_member_id={integration_member_id}
    &integration_team_id={integration_team_id}
    &modality={modality}
    &feature={feature}
    &environment={environment}
  ```

  ```text Junction IDs theme={null}
  https://{integration_slug}.ehr.junction.com/auth/launch
    ?member_id={member_id}
    &team_id={team_id}
    &modality={modality}
    &feature={feature}
    &environment={environment}
  ```
</CodeGroup>

| Parameter               | Description                                                                 |
| ----------------------- | --------------------------------------------------------------------------- |
| `integration_member_id` | Your unique reference for the member. Mutually exclusive with `member_id`.  |
| `member_id`             | Junction-issued member ID. Mutually exclusive with `integration_member_id`. |
| `integration_team_id`   | Your unique reference for the team. Mutually exclusive with `team_id`.      |
| `team_id`               | Junction-issued team ID. Mutually exclusive with `integration_team_id`.     |
| `modality`              | `feature_embed` or `link_out`.                                              |
| `feature`               | Supported feature slug, such as `order_creation` or `team_config`.          |
| `environment`           | `sandbox` or `production`.                                                  |

## Feature Embed flow

```mermaid theme={null}
sequenceDiagram
    autonumber
    participant PartnerApp as Your Web App
    participant Junction as Junction App Embed
    participant Continuation as Session Continuation URL
    participant API as Junction Management API

    PartnerApp->>Junction: Load Fast Launch URL in iframe
    alt Compatible Junction session exists
        Junction->>Junction: Route directly to requested feature
    else Session missing or incompatible
        Junction-->>PartnerApp: Redirect iframe to session continuation URL
        PartnerApp->>Continuation: Request with launch parameters
        Continuation->>Continuation: Validate app session and parameters
        Continuation->>API: Create dashboard URL
        API-->>Continuation: Post-authorization URL
        Continuation-->>PartnerApp: 307 redirect to post-authorization URL
        PartnerApp->>Junction: Open post-authorization URL
        Junction->>Junction: Configure session and route to feature
    end
```

## Link Out flow

For Link Out, open the same Fast Launch URL in a top-level browser context. If Junction can reuse the session, it routes immediately. Otherwise, it redirects the browser to your session continuation URL before returning to Junction with a new post-authorization URL.

## Implementation notes

* Keep the `feature`, `modality`, and `environment` values in your own allowlist.
* Prefer partner references (`integration_member_id` and `integration_team_id`) when they are already available in your client runtime.
* Your session continuation endpoint must validate the current partner session before creating the dashboard URL.