Coding (Platform)

Express: Sessionize event activity for batch worker activity stream

A service boundary accepts valid traffic but mishandles duplicate, stale, or unauthorized records. The affected area is batch worker.

Repair the batch worker activity stream implementation so it splits activity after the configured inactivity gap and counts sessions per actor.

Evidence

Affected surface: Express / batch worker.
Observed failure family: sessionize event activity.
Scope policy: retained must equal true.

What this task practices

This coding (platform) exercise trains the same sequence expected in an interview: understand the prompt, make assumptions explicit, produce a concrete answer, and explain the decisions behind it. The task is marked hard difficulty. The private workspace adds the tools required by this round, such as recording, code execution, diagrams, evidence panels, or structured notes. It also preserves the attempt so later feedback can be compared with previous work. Evaluation is based on task-specific criteria and the candidate seniority selected in the preparation path. Public pages never expose the reference solution, hidden tests, evaluator instructions, or another candidate’s work.