[FEATURE] Surface detailed session usage stats in VS Code / Cursor extension

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

Problem Statement

When using the Claude Code extension in VS Code / Cursor, the /usage command only opens an "Account & Usage" popup showing my auth method, email, organization, and a link to manage usage on claude.ai. It does not show the per-session breakdown of tokens, cost, cache reads/writes, or lines changed.

This means I have no in-IDE visibility into:

• How much a given session is costing me
• Token consumption broken down per model
• Cache hit/miss ratios (useful for understanding prompt efficiency)
• Wall vs. API duration

To get this information, I have to leave the extension UI and run claude in a terminal, which fragments the workflow.

Proposed Solution

Bring the CLI's detailed session usage output into the VS Code / Cursor extension. Ideally, running /usage (or /cost / /status) inside the extension would show the same breakdown that the terminal CLI shows, for example:

Session

  Total cost:            $0.0322
  Total duration (API):  2s
  Total duration (wall): 21s
  Total code changes:    0 lines added, 0 lines removed
  Usage by model:
       claude-opus-4-8:  1.7k input, 31 output, 21.3k cache read, 2.0k cache write ($0.0322)

This could be rendered either as a message in the chat panel (matching CLI behavior) or as a dedicated "Usage" panel in the extension sidebar.

Alternative Solutions

• Running claude in VS Code's integrated terminal instead of using the native extension — this works but loses the inline diff UI and conversation history the extension provides.
• Running both side-by-side (extension for editing, a terminal session for stats), clunky and duplicates work.

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

1. I start a Claude Code session in the VS Code extension to refactor a module.
2. After ~30 minutes of back-and-forth, I want to check how much the session has cost and whether prompt caching is working well.
3. I run /usage in the extension — but I only get the "Account & Usage" popup pointing me to claude.ai.
4. With this feature, /usage would instead show me the per-session token/cost/cache breakdown directly in the extension, the same way the terminal CLI does.
5. This would save me from having to spin up a separate claude terminal session just to check cost and cache efficiency, and would let me tune my prompts (e.g., to improve cache reuse) without leaving the IDE.

Additional Context

**Screenshot:

<img width="749" height="452" alt="Image" src="https://github.com/user-attachments/assets/535896f6-82d2-4205-86c3-78cc177a5366" />

**
Extension /usage output: shows only "Account & Usage" popup with auth method, email, organization, and "Usage tracking is only available for Claude AI subscribers" — (attach your first screenshot)

Environment:

• Editor: VS Code and Cursor (both affected)
• Extension: Claude Code
• Billing: Anthropic API (pay-as-you-go)