[BUG] Regression in 1.24012.1.0 (Windows/MSIX): webview repeatedly unresponsive during conversations -> white screen (kill and reload loop)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet (similar blank-screen reports exist, e.g. #51143 / #44558 / #56763, but none tied to the 1.24012.1.0 rollout)
• [x] This is a single bug report
• [x] I am using the latest version (1.24012.1.0, newer than the 1.24012.0 currently on winget)

What's Wrong?

Since the desktop app auto-updated to 1.24012.1.0 (installed 2026-07-22 07:35 JST), the main claude.ai webview repeatedly becomes unresponsive during conversations. The app detects it and kills/reloads the webview, which shows as a white/blank window for 30–60+ seconds on every affected conversation. On one occasion the window stayed blank until all processes were killed manually.

This is a clear regression: main.log contains zero unresponsive events before the update, and 5 events in the ~27 hours after it:

2026-07-22 09:56:27 [info] Main webview is unresponsive, will kill and reload
2026-07-22 10:48:03 [info] Main webview is unresponsive, will kill and reload
2026-07-22 13:07:48 [info] Main webview is unresponsive, will kill and reload
2026-07-22 17:12:15 [info] Main webview is unresponsive, will kill and reload
2026-07-23 10:24:01 [info] Main webview is unresponsive, will kill and reload

(The package folder Claude_1.24012.1.0_x64__pzs8sxrjxfjjc was created 2026-07-22 07:35 JST — the first event is ~2.5 h later.)

Observations

• Before each hang the renderer process balloons: e.g. at 10:20 the renderer was at 942 MB RSS (total app tree ~2 GB); after the kill/reload the fresh renderer starts at ~120 MB. System RAM was not exhausted (3+ GB free of 16 GB).
• Sentry caught: { entries are logged at the moment of each unresponsive event, so telemetry for these hangs should already be on your side.
• The hang correlates with active conversations (it happens "every conversation" from the user's perspective); the app is also running local Claude Code sessions via the bridge.
• One earlier instance (started 7/22 17:11) never recovered visually — the window stayed white until all Claude.exe processes were force-killed and the app relaunched.

Environment

• Windows 11 Home 22621, 16 GB RAM
• Claude Desktop 1.24012.1.0, Microsoft Store (MSIX) install, package Claude_pzs8sxrjxfjjc
• Note: #56763 (also MSIX, blank screen) was closed as invalid with the comment that the MSIX path is "unusual" — please don't discard this one on those grounds; the Store build auto-updates and cannot be pinned or rolled back by the user.

Steps to Reproduce

1. Windows + Microsoft Store build 1.24012.1.0
2. Use the app for normal conversations
3. Within hours, the webview hangs → white window → auto kill/reload (log lines above)

Expected

Conversations should not hang the renderer; no white/blank window during normal use.