Under the hood
Claude Code now tracks CPU usage per phase for individual shell tool calls
What
Claude Code has a new helper that computes a file path used to track CPU usage broken down by phase for shell tool calls, skipping session IDs that look like sub-paths or start with "cc-". This is used to log a tengu_tool_cpu_by_phase telemetry event, and it fails gracefully with a fallback message if the tracking file can't be created.
Why
This gives more detailed CPU usage data for shell commands, broken down by phase, which can help diagnose performance issues in specific stages of command execution.