Renderer unresponsive (6-7s freeze) in execEditLength when computing large file diffs

[Domovikx]

Description

Description:
Renderer becomes unresponsive for 6-7 seconds when computing file diffs in a session with large files. The hang occurs in the diff algorithm (execEditLength → structuredPatch → createTwoFilesPatch → resolveFileDiff) triggered by CollapsibleRoot components rendering file diffs.

Two consecutive sessions crashed the same way (17:18 and 17:35). The renderer recovered on its own each time (~6s), but the app is unusable during the freeze.

Full debug logs attached.

OpenCode version:
1.17.8 (packaged, win32 x64)

Steps to reproduce:

1. Open a session that contains a file diff with many changes or a very large file
2. The CollapsibleRoot component tries to compute structuredPatch → execEditLength
3. The O(n*m) diff algorithm blocks the main thread for 6+ seconds
4. Electron marks the window as "renderer unresponsive"

Operating System:
Windows 11

Terminal:
Windows Terminal

Plugins

OpenCode version

1.17.8 (packaged, win32 x64)

Steps to reproduce

1. Open a session that contains a file diff with many changes or a very large file
2. The CollapsibleRoot component tries to compute structuredPatch → execEditLength
3. The O(n*m) diff algorithm blocks the main thread for 6+ seconds
4. Electron marks the window as "renderer unresponsive"

opencode-debug-20260618T143520.zip

Screenshot and/or share link

No response

Operating System

Windows 11

Terminal

Windows Terminal

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Desktop v1.16.0 Windows: renderer unresponsive / UI freeze when computing diff of large files #30906: Desktop renderer unresponsive / UI freeze when computing diff of large files (Windows)
• Renderer freezes / "app not responding" when computing large diffs #32046: Renderer freezes / "app not responding" when computing large diffs
• The opencode Desktop UI freezes for approximately 10–12 seconds when rendering file diffs. #31195: Desktop UI freezes for approximately 10–12 seconds when rendering file diffs
• Desktop app renderer freezes/crashes repeatedly #31594: Desktop app renderer freezes/crashes repeatedly

If your issue is distinct from the above, please add context explaining how it differs.