Returns the candidate's message and activity thread — messages sent to or from the candidate (including messages posted by external users) and interview/meeting-time proposal events — ordered newest first.

The thread is scoped to the candidate, not to the positionId in the path (which only governs access): for a caller who can manage the candidate's other positions, it merges the messages from the same person's applications on those positions.

Supports pagination via the skip query parameter (50 records per page). By default, pending/delayed scheduled messages and cancelled messages are excluded; pass include_delayed=1 to also include the pending/delayed ones (cancelled messages remain excluded).