[Bug] SessionReview blocks UI thread due to synchronous file diff calculation (compounded by corporate encryption systems) #35531

Description

The UI rendering thread experiences a complete freeze (renderer unresponsive) during the rendering of the SessionReview component.

Investigation of the logs revealed a severe frontend performance issue: the SessionReview component synchronously executes heavy file diff calculations on the main thread for all modified files without any chunking or offloading to a Web Worker. For large projects (such as FPGA repositories), this freezes the UI for several minutes.

Root Cause Stack Trace (captured twice in window.log):

Plaintext
execEditLength → diffLines → structuredPatch → createTwoFilesPatch
→ parseDiffFromFile → fileDiffFromContent → fileDiffFromPatch
→ resolveFileDiff → SessionReview
Compounding Factors (Corporate File Encryption):

Encryption Interference: The host machine uses a corporate file encryption/DLP system. When Git attempts to perform background operations (git gc / git repack), the encryption software interferes with file access or blocks temporary object creation, throwing false-positive repository corruption errors in opencode.log:

Plaintext
cleanup failed: unable to normalize alternate object path: E:\1_code\sw640.git\objects
fatal: bad tree object 012e04dcc134f9fe7120e142fba8d5460f759c77
fatal: failed to run repack
Vicious Cycle: Each time the encryption software blocks or disrupts Git, it triggers abnormal .git state change events. This alerts the OpenCode watcher backend, forcing a snapshot / project copy refresh, which ultimately re-triggers the synchronous SessionReview diff calculation in an endless loop.

Periodic Re-trigger: The watcher backend re-initializes every 60 minutes by design. Each hourly restart triggers a project copy refresh + booting location services, worsening the freeze cycle under encrypted environments.

Plugins

Can’t you just give us a damn switch to turn off those fucking censorship scans? Batshit

OpenCode version

all

Steps to reproduce

1. Open a large project or FPGA repository containing many/large files on a workstation with corporate file encryption (DLP/Endpoint Protection enabled).
2. Allow OpenCode or Git to run background maintenance (git gc), which will fail or throw object access errors due to the encryption wrapper.
3. Trigger the SessionReview component rendering (or wait for the 60-minute watcher backend automatic restart to force a project refresh).
4. Observe that the UI completely freezes (renderer unresponsive) for several minutes while the main thread synchronously executes diffLines.

Screenshot and/or share link

No response

Operating System

window10

Terminal

No response