Show current context window usage information in agent panel for external agents

[gayanper]

Body

What are you proposing?

Show the current context window usage in the agent panel for external agents which already supports publishing the draft usage notifications. currently the claude acp agent wrapper has a working implementation and I have personally integrated that in my WIP vscode acp extension at https://github.com/gayanper/vscode-acp-provider. I would like to see this feature in Zed so I can switch to using Zed with Claude Code instead.

Why does this matter?

To use external agent effectively without consuming tokens too much with unnecessary large contexts.

Are there any examples or context?

Percentage text would satisfies the requirements.

Possible approach

If a usage notification is received, render the information.

[Nyrok]

Context window visibility is useful. The next step is reducing unnecessary token use upfront.

Most agents burn tokens because their system prompts are unstructured prose. The model re-parses the same implicit information on every turn. Structured prompts, where role, constraints, context, and objective are in explicit blocks, pack more intent per token and are easier for the model to attend to.

I've been building flompt for exactly this, a visual prompt builder that decomposes prompts into 12 semantic blocks and compiles to Claude-optimized XML. The structured output is typically 30-50% more compact than equivalent prose prompts. Open-source: github.com/Nyrok/flompt

[pyk]

related discussion #49472