[FEATURE] "Agent mode" analogous to "Plan mode" but for forcing Claude Code to spawn subagent

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I struggle to make Claude Code spawn subagents without manually saying it in the prompt.

This is despite having stuff like this in my user-level CLAUDE.md file:

## Task Delegation

**IMPORTANT**: Unless the task is very simple, you should use the Task tool to delegate the task to a specialized agent.

It is your duty to identify the most appropriate agents for the task, and whether the agents can work in parallel or
sequentially.

Claude routinely ignores that instruction.

Proposed Solution

It would be helpful to have an "Agent Mode" toggle (similar to "Plan Mode") that can be activated either via SHIFT+TAB or via some sort of shortcut, which will use a custom system prompt to force Claude Code to spawn a subagent to do its work, no matter what.

Priority

Medium - Would be very helpful

Feature Category

Performance and speed