Desktop app becomes unresponsive ("Not Responding") — main-process event loop repeatedly blocked, persists across restarts (v1.18286.0.0, Windows)

Summary

On Windows, the Claude desktop app periodically freezes and shows "Not Responding." Fully quitting and relaunching does not fix it — every fresh launch starts stalling again within minutes. main.log shows the Electron main process event loop being blocked for 2–4 s at a time, repeatedly, which is enough for the window to go unresponsive.

Environment

• App version: 1.18286.0.0 (x64)
• OS: Windows (MSIX / Microsoft Store packaged install — Claude_pzs8sxrjxfjjc)

Steps to reproduce

1. Use the desktop app normally over a session.
2. UI freezes / Windows marks the window "Not Responding."
3. Fully quit and relaunch — freezing recurs within minutes.

Evidence (main.log) — stalls resume immediately after each restart

2026-07-07 15:16:22 [warn] [event-loop-stall] main process blocked for  784ms (total 1,  cumulative   784ms, rss 205MB)
2026-07-07 15:19:31 [warn] [event-loop-stall] main process blocked for 2594ms (total 3,  cumulative  5015ms, rss 253MB)
2026-07-07 15:20:16 [warn] [event-loop-stall] main process blocked for 3141ms (total 6,  cumulative 13247ms, rss 262MB)
2026-07-07 15:21:12 [warn] [event-loop-stall] main process blocked for 4294ms (total 9,  cumulative 22880ms, rss 258MB)

• 1,165 stall warnings across 7 days (long [likely sleep/wake] entries excluded as machine-sleep).
• Process before the last restart reached (total 361, cumulative 483058ms) — ~8 min of genuine main-thread blocking.

Recurring startup error on every recent launch:

[warn] [watch-record] failed to subscribe to swift events
(intermediate value).default.on is not a function
  at ...app.asar\.vite\build\index.js:4455:7916

Ruled out

• Not a memory leak (RSS stable ~205–262 MB during stalls).
• Not a renderer/GPU crash (no render-process-gone / gpu-process-crashed).

Expected

Main process stays responsive; blocking work runs off the main thread / asynchronously.