statusLine: expose tool_use_count in JSON payload

Feature Request

Summary

Add a tool_use_count (or similar) field to the JSON payload piped to the custom statusLine.command script.

Use case

Users with a custom status line want to display session activity at a glance. The number of tool calls made in a session is a useful complement to the existing context_window usage data — it reveals how the context was consumed (many small precise calls vs. few large ones), which the token count alone does not convey.

Current behavior

The JSON payload contains context_window (token usage) but no information about how many tool calls have been made in the session.

Expected behavior

A field like:

{
  "tool_use_count": 42
}

included in the statusLine JSON payload, allowing custom scripts to render a combined activity indicator such as ⚙ 42 · ≈ 38k.

Related

• anthropics/claude-code#39861 — exposes update availability in the same JSON payload