Description

Fixes #4188

Problem: When using the Responses API (default in OpenAI Agents SDK), agent instructions are passed as a separate parameter to responses.create(instructions=...) — NOT as role: "system" messages in the input. The Response object stores these on its .instructions attribute. However, _collect_system_instructions() only scans input messages for role in {"system", "ai"}, so instructions were never captured in gen_ai.system_instructions.

Fix: In _build_content_payload() for ResponseSpanData, after the existing input-message-based system instruction collection, add a fallback that reads response.instructions:

if capture_system and not payload.system_instructions:
    response = getattr(span_data, "response", None)
    instructions = getattr(response, "instructions", None)
    if isinstance(instructions, str) and instructions:
        payload.system_instructions = [{"type": "text", "content": instructions}]

This works for both Responses API and Chat Completions API (which already worked via input messages).

Testing: Added unit test with mock Response object containing .instructions.

Type of Change

• Bug fix (non-breaking change which fixes an issue)