VS Code: diffs open in wrong editor group, no control over tab behavior

Problem

The latest update changed how diffs/file previews open in the VS Code extension. Two issues:

1. Every Edit/Write opens a new diff tab — they stack up endlessly. No way to reuse a single preview tab.
2. Diffs open in the wrong editor group — if you have a split layout (editor left, Claude Code right, terminal bottom), diffs land on the right side (Claude's panel) instead of the left where your actual files are. There's no setting to control which editor group diffs open in.

Expected behavior

• Diffs should reuse a single preview tab instead of spawning a new one every time
• There should be a setting to control which editor group diffs open in (e.g., claudeCode.diffEditorGroup: "first")
• At minimum, respect VS Code's workbench.editor.enablePreview setting so diffs open as replaceable preview tabs

Current workaround

None. Ctrl+W to manually close each diff tab.

Related issues

• #25018
• #29388
• #11411

Environment

• Windows 11
• VS Code (latest)
• Claude Code extension (latest update as of 2026-04-04)