# Feature: Async Lifecycle

Specifies the asynchronous communication model and connection lifecycle management for the Exasol WebSocket client, including non-blocking I/O via tokio and connection state tracking.

## Background

All WebSocket communication is asynchronous using tokio. Send and receive operations are non-blocking, returning Futures that support cancellation via tokio task cancellation. The system tracks connection state throughout the lifecycle (connecting, authenticated, idle, closed) and prevents invalid operations in wrong states. Disconnections are detected and reported to the caller but automatic reconnection is not performed -- explicit reconnection is required.

## Scenarios

### Scenario: Non-blocking send

* *GIVEN* an authenticated WebSocket session exists
* *WHEN* sending a command
* *THEN* it SHALL NOT block the calling thread
* *AND* it SHALL return a Future that resolves when the send completes

### Scenario: Non-blocking receive

* *GIVEN* an authenticated WebSocket session exists
* *WHEN* waiting for a response
* *THEN* it SHALL NOT block the calling thread
* *AND* it SHALL support cancellation via tokio task cancellation

### Scenario: Concurrent requests

* *GIVEN* an authenticated WebSocket session exists
* *WHEN* multiple requests are in-flight
* *THEN* it SHALL correctly match responses to their requests
* *AND* it SHALL maintain request ordering where required by protocol

### Scenario: Connection state tracking

* *GIVEN* a WebSocket connection is active
* *WHEN* a connection is active
* *THEN* it SHALL track connection state (connecting, authenticated, idle, closed)
* *AND* it SHALL prevent invalid operations in wrong states

### Scenario: Automatic reconnection

* *GIVEN* a WebSocket connection is active
* *WHEN* a connection is dropped unexpectedly
* *THEN* it SHALL detect the disconnection
* *AND* it SHALL provide error information to the caller
* *AND* it SHALL NOT automatically reconnect (explicit reconnection required)

### Scenario: Heartbeat and keepalive

* *GIVEN* a WebSocket connection is active
* *WHEN* a connection is idle
* *THEN* it SHALL send keepalive messages if required by the protocol
* *AND* it SHALL detect connection failures via missing heartbeat responses
