What changed
Serialization mismatch. Integer-to-string moves are the usual cause and the usual outage.
Affects GET /agents/sessions/{session_id}/artifacts.
null|string → string
Who is affected
Code that sends GET /agents/sessions/{session_id}/artifacts (after).
Before and after
| Where | Before | After |
|---|---|---|
| GET /agents/sessions/{session_id}/artifacts · after | null|string | string |
Code that breaks
// payload.after // was: null|string // now: string
Based on OpenAI’s published API specification. How severity is decided.