When asking GPT 5.6 Luna for one object conforming to a strict JSON schema, OpenRouter sometimes returns several complete, schema-shaped objects concatenated in a single choices[0].message.content string.
I was able to reproduce this on 4 requests out of 10 to OpenRouter but calling OpenAI’s API directly had 0 failures out of 11 requests.
Full repro steps and examples on my github at polybuildr/openrouter-luna-schema-bug (but can’t include links).