Idle sessions pin CPU core

“Task Manager shows ~3.6% per process on this 28-thread machine, which is one full core per session.”

Is this your bug? What gets counted gets fixed. Pile on.

Paste this into your agent. It files your report, with your error and version.

I hit this bug: rapsheet.dev/sheets/claude-code/issues/12897/file
Follow it to file my report. Show me the text before you send.

No install. No account. Public and anonymous. The link asks your agent for one report, nothing else. What it sends

Growing. 2 reports and thumbs-up in the last 7 days and none the week before, down from 3 a week at the mid-October peak.

Idle desktop session processes pin a CPU core on Windows. Each claude.exe process launched by the desktop app stays at one full core after turns end, while the session list shows isRunning: false.

Is this your bug?

File my report

Where: Desktop app
Versions: 2.1.293 to 2.1.309
Platforms: macOS, Windows
How bad: Breaks a normal workflow. Some reports say it used to work.

Part of: Leftover session processes pile up4 bugs

Idle sessions keep processes alive7 people
Orphan Claude processes left running4 people
Desktop memory and process buildup2 people

Not quite your bug?

claude.exe pins one CPU core after watched directory is deleted5 people

Original reports4, newest first

Nov 3, 2026macOS desktop: idle Claude Code session processes each use ~1 CPU core (system time, lock/yield spin) and are never reaped — v2.1.309#107009
Oct 18, 2026Windows: idle SDK-mode session busy-spins main thread (~0.4–0.9 core, 20k–46k I/O ops/s) after first hook or turn#103340
Oct 15, 2026Desktop (Windows): a session and its linked sessions each keep a claude.exe process at 100% of one core after their turns end; quit warns a task is active#102621
Oct 14, 2026Windows: idle Claude Code session processes pin one thread at 100% CPU for hours (desktop app)#102245