Task model

A task is a MongoDB document with the following fields.

Field	Type	Meaning
_id	ObjectId	MongoDB primary key.
payload	any	Application data for the job.
status	string	new, pending, failed, successful.
priority	int	Higher values dequeue first.
createdAt	float	Creation timestamp (seconds).
modifiedAt	float	Last update timestamp (seconds).
scheduledAt	float or null	Earliest time the task can be leased.
assignedTo	string or null	Worker tag that owns the lease.
leaseId	string or null	Identifier for the lease.
leaseExpiresAt	float or null	Lease expiration timestamp.
retries	int	Number of failures so far.
errorMessage	string or null	Last failure message.
dedupeKey	string or null	Idempotency key (string only).
rateLimitKey	string or null	Per-key rate limit identifier.

Task objects in code are a thin wrapper around the underlying document. They can be converted to dictionaries via dict(task).