[FEATURE]: Allow checking context window inside subagents #53024

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

In opencode v1, we can see subagent's context window percentage. This is now gone (or at least not on by default and I cannot find it) in opencode v2. This removes the chance for the human observer to look at the context window usage.

Use case: For example, a sub-agent is being tasked with too much things that it cannot handle inside a small context window. a human watching can determine if it it about to reach a "comfortable" context window (e.g. 40% or 80%) and interrupt it, asking the dispatcher to resume the agent to "wrap up your work, your context window is running out"; and start another sub-agent.

A even better approach would be to automatically set a threshold, which after met would inject the sub-agent with a message, instructing it to wrap up and report.