Ticket
A written unit of work in a tracking tool: one bug to fix or one feature to build, assigned to a developer.
What it tells you about a developer
Developers who write clear tickets and bug reports can specify a problem precisely before solving it, which is rarer than it sounds. Public issue activity in open source repositories is verifiable evidence of the skill.
Tickets live in tools like Jira, Linear, or GitHub Issues, and they move through states: open, in progress, in review, done. A ticket is the unit developers pick up, estimate, and complete. On GitHub, the equivalent object is called an issue.