Improve context window transparency: `/context` command providing detailed context window overview

What feature would you like to see?

Background
/status already reports token totals (Input/Output/Total), but it doesn’t show where tokens come from. This lacks the granularity needed to diagnose truncation and optimize prompts/context.

Proposal
Introduce a /context command that reports token usage by component:

• System Prompt (core instructions/behavior)
• System tools (built-in functionality)
• MCP tools (Model Context Protocol integrations)
• Instruction files (e.g., AGENTS.md, project context)
• History (current conversation)

Shows tokens used per component and % of remaining context window.

Are you interested in implementing this feature?

I’d like to give it a try. However, due to my lack of competence in Rust, I don’t think I could meaningfully contribute to the implementation.

Additional information

_No response_