Scan command context
====================

The scan command context contains the scan-specific runtime information used by
the observation supervision layer and by the scan consistency policy.

It links an accepted `Scan` command to the runtime information required to
evaluate the scan lifecycle consistently. This includes the devices selected for
the scan, the optional scan schedule, and the retained scan context used after
the `Scan` command has completed.

Scan command context handling is different from the default command context
lifecycle. For most commands, the command context is discarded after command
completion. For `Scan`, the completed context can be retained because the scan
lifecycle may still be relevant after the command itself is no longer active.

This is required in two cases:

* for legacy scans, where the command context is used while the CSP Subarray is
  expected to be in `SCANNING`;
* for scheduled scans, where the command context must also be preserved while
  the scan is pending and the CSP Subarray may still be in `READY`.

The scan-specific command context documentation is organised as follows.

.. toctree::
    :maxdepth: 1
    :caption: Scan command context

    configured_devices
    scheduled_scan
    retained_scan_context
    ../../consistency_policy/scan_scheduled_policy