Desktop app (Windows): background sessions pause and timer resets when switching to another session

Environment

• Platform: Windows 11 Pro (10.0.26200)
• App: Claude Code Desktop app
• Version: 1.2278.0 (e5213f)
• First observed: ~April 13-14, 2026

Summary

When a session is running work in the background (agent call, long bash command, web research, etc.), switching to another session via the sidebar appears to suspend the first session's execution. On return, the elapsed-time timer resets to zero and little to no progress has been made, sometimes none at all.

Steps to reproduce

1. In Session A, kick off a long-running task (e.g., an Agent call that will take 30-60 seconds, or a long Bash command)
2. While Session A is processing, switch to Session B via the sidebar
3. Wait 60-120 seconds
4. Switch back to Session A
5. Observe: elapsed-time counter has reset, and the in-progress tool call has not advanced (or has advanced only slightly)

Expected behavior

Sessions run independently of which one is currently visible. Per the docs, background work should continue regardless of focus. Related issue #36418 describes the same class of bug for the CLI variant.

Actual behavior

The background session is effectively paused while not visible. The timer reset on return is the strongest signal: if work were continuing and only the display were stale, the timer would show real elapsed time.

Architectural note

The desktop app does not support multiple visible session windows; sessions are switched one-at-a-time via the sidebar. This means users cannot work around the bug by keeping a session in focus while doing other work, because the workflow requires switching away.

Hypothesis

Likely Chromium/Electron background-window throttling suspending the render process or JS event loop. Flags like \--disable-background-timer-throttling\, \--disable-backgrounding-occluded-windows\, and \--disable-renderer-backgrounding\ would address this class of issue but do not appear to be set (or exposed in settings).

Impact

Fundamentally breaks the multi-session workflow. Users cannot run any long-running task in one session and use another in the meantime.