Desktop app: diff view lacks persistent defaults (uncommitted-only mode, collapsed files)

Description

The diff/changes view in the Claude Desktop app has two display behaviors that reset every time a new session starts or the app restarts, with no way to set them as persistent defaults:

1. View mode (branch-cumulative vs. uncommitted-only): a toggle switches between showing the branch-cumulative diff (vs. the detected base branch, apparently following origin/HEAD) and showing only uncommitted/not-yet-committed changes in the working tree. This choice is remembered while the diff window stays open in the same session, but resets to the default (branch-cumulative) view on a new session or app restart.

1. File fold state: when the diff view lists multiple changed files, each file's diff appears expanded by default. There's no setting to have files start collapsed (folded) by default, which would make it easier to scan the file list first on diffs touching many files, and expand only the ones you need.

Neither behavior has a documented way to be configured as a persistent default — no settings.json key, and no control under Settings > Claude Code.

Steps to reproduce (view mode)

1. Open a project with uncommitted changes on a feature branch in Claude Desktop.
2. Open the diff/changes view; it shows the branch-cumulative diff against the base branch, with files expanded.
3. Toggle the view to "uncommitted changes only".
4. Close and reopen the diff view in the same session → the toggle choice is kept.
5. Start a new session (or restart Claude Desktop) → the view resets to branch-cumulative; the toggle has to be reselected.

Expected behavior

• The view-mode toggle choice persists per project/folder (similar to how the permission mode selector is remembered per folder), or a settings.json key (e.g. diffView.defaultMode) lets the user set "uncommitted changes only" as the default.
• A setting (UI toggle or settings.json key, e.g. diffView.collapseFilesByDefault) to have each file's diff start collapsed in the diff view, expandable on demand.

Environment

• Claude Desktop app, Windows
• Git repository with a remote (origin)