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

# Control Existing Sessions

> Use a session ID to inspect and continue an existing Blocks session.

If you already have a `session_id`, you can treat that session as a durable API resource. This lets backend services, internal tools, or operators reconnect to work that is already in progress instead of creating a new session each time.

## What you can do

* Fetch session metadata to understand current state and links
* List messages to read the full conversation history
* Send follow-up messages to continue or redirect the session
* Poll `final_message` to wait for the next assistant result

## Common pattern

Use this flow when a session was created earlier by another system, user action, or automation step:

1. Store the `session_id` when the session is created.
2. Load the session later with `GET /rest/v1/sessions/{session_id}`.
3. Read prior messages with `GET /rest/v1/sessions/{session_id}/messages`.
4. Send a new instruction with `POST /rest/v1/sessions/{session_id}/messages`.
5. Poll the returned `_links.final_message.href` to receive the assistant's next completed reply.

## Example

```javascript theme={null}
const headers = {
  Authorization: `ApiKey ${process.env.BLOCKS_API_KEY}`,
  "Content-Type": "application/json",
};

const sessionId = "a196cec6-49cb-4c48-8e4c-2707fb5d6709";

const session = await fetch(
  `https://api.blocks.team/rest/v1/sessions/${sessionId}`,
  { headers },
).then((r) => r.json());

const history = await fetch(session._links.messages.href, { headers }).then((r) => r.json());

const followup = await fetch(
  `https://api.blocks.team/rest/v1/sessions/${sessionId}/messages`,
  {
    method: "POST",
    headers,
    body: JSON.stringify({
      message: "Summarize the current plan and suggest the next best action.",
    }),
  },
).then((r) => r.json());

const finalMessage = await fetch(followup._links.final_message.href, { headers }).then((r) => r.json());
```

## Good fits

* Reopening a session from your own application UI
* Letting support or operations tools inspect active work
* Handing a live session from one system step to another
* Continuing long-running work without losing context

See also: [Get Session](/rest-api/sessions/get), [List Messages](/rest-api/sessions/messages), and [Send Messages](/rest-api/sessions/follow-up).