Show context window usage (%) next to the token count in the agent header

Today each agent shows at the top how many tokens it has used so far. That's useful, but it doesn't tell me how close the agent is to filling its context window. That's the number that matters day to day. When the context gets close to full, the CLI starts compacting or summarizing the conversation, and the agent loses detail. Right now I can't see that coming without opening the terminal and checking by hand.

Suggestion: next to the token count, show the share of the context window already used, for example "84k tokens · 42% context".

It should stay discreet. A small label or a thin progress bar is enough. Color could signal when it needs attention:

• Neutral or green below about 60%
• Yellow or amber from about 60% to 80%
• Red above about 80%, when it may be time to compact, clear or hand off to a new session

Nice to have:

• A tooltip on hover with the exact numbers (used / total context size) and the model in use

Why it helps: when several agents run in parallel, this would show which ones are about to lose context, so I can step in (compact, clear, or start a fresh session) before quality drops in the middle of a task.