OpenAI/Codex OAuth streams can return text through response.output_text.delta while the final response.completed payload has response.output set to null. That made PicoClaw report an empty model response even though the backend returned valid content.
Accumulate streamed output_text delta events during the Codex response stream and use them as a fallback when the parsed final response has no content. Add a regression test covering the null final output case from issue #2953.
SebastianBoehler