Write/Edit tool silently fails after extension update (file unchanged, no error thrown)

Environment

• Claude Code VSCode Extension (updated 2026-03-19)
• OS: Ubuntu Linux (6.17.0-19-generic)
• Project: Electron + React + TypeScript (Vite)

Symptom

After today's extension update, the Write and Edit tools intermittently fail silently:

• No error is thrown
• The tool reports 'updated successfully'
• But the file on disk is unchanged (verified with grep immediately after)

Reproduction

Occurs when:

1. Writing a large file (200+ lines) with the Write tool
2. Editing files with multi-line old_string in the Edit tool

The failure is non-deterministic — the same operation sometimes succeeds, sometimes silently fails within the same session.

Observed in this session

• Header.tsx (250+ lines): Write reported success, file remained at 183 lines (old content)
• preload-bridge.ts: Edit reported success, grep confirmed 0 matches for new content
• ipc-channels.ts: Edit reported success, grep confirmed 0 matches for new content
• locales/en/common.json and ko/common.json: Edit reported success, new keys absent

Impact

• Runtime crashes from calling non-existent methods (silently added to ipc-service.ts but never reached preload-bridge.ts)
• TypeScript errors masked because dependent handler code also failed to apply
• Requires re-applying all changes manually after grep verification

Workaround

Verify every Write/Edit with an immediate grep check:

grep -c "unique_new_string" target_file

If count is 0, the write failed — retry the operation.

Note

This behavior did not occur before today's extension update.