Why

code_mode_only filters code-mode nested tools out of the top-level tool list. For multi-agent v2, we need a rollout shape where the collaboration tools remain callable as normal model tools without also being embedded into the code-mode exec tool declaration.

Related to this: https://openai-corpws.slack.com/archives/C0AQLHB4U75/p1778660267922549

What Changed

• Adds features.multi_agent_v2.non_code_mode_only, including config resolution, profile override handling, and generated schema coverage.
• Introduces ToolExposure::DirectModelOnly so a tool can be included in the initial model-visible list while staying out of the nested code-mode tool surface.
• Applies that exposure to the multi-agent v2 tools when the new flag is set: spawn_agent, send_message, followup_task, wait_agent, close_agent, and list_agents.
• Updates code-mode-only filtering so direct-model-only tools remain visible while ordinary nested code-mode tools are still hidden.

Verification

• Added config parsing/profile tests for non_code_mode_only.
• Added tool spec coverage for the code-mode-only multi-agent v2 exposure behavior.