Subagents can spawn subagents five deep, and auto mode now classifies spawns before launch

What this changes for operators

• 2.1.172 lets a subagent spawn its own subagents up to 5 levels deep (new capability and a new governance surface); 2.1.178 then made the auto-mode classifier evaluate a spawn before launch, closing a gap where a deeply nested agent could request an action the operator's policy would block at the top.
• Operators running under auto mode should upgrade past 2.1.178 before trusting a delegation tree, and use argument-aware permission rules to cap what spawned agents can do.