PR widget diff stats include untracked files outside working directory scope

Description

The PR creation widget in Claude Code's UI shows diff stats (e.g., +78284 -1375) that appear to include untracked files from the entire repository, not just the changes relevant to the current work. This is confusing and potentially misleading when deciding whether to create a PR.

Steps to reproduce

1. Work in a monorepo subdirectory (e.g., mr-esp32/speed-cal/)
2. Have large untracked files elsewhere in the repo (e.g., shared/pcb/ with ~1.5MB of KiCad PCB files from a previous session)
3. Make a small, focused change (e.g., split one HTML file into three — net +40 / -1370 lines)
4. Observe the PR widget at the bottom of the Claude Code UI

Expected behavior

The diff stats should reflect only the staged/committed changes relevant to the current branch vs. main, or at minimum only tracked changes. In this case, the actual committed change was +1410 -1370.

Actual behavior

The widget showed +78284 -1375, which includes ~1.5MB of untracked KiCad PCB files, .claude/ directories, and other unrelated untracked content from the broader monorepo. The -1375 was close to the real deletion count, but the +78284 was wildly inflated.

Impact

• Misleading diff size may cause hesitation about creating PRs
• May also contribute to context window pressure if Claude Code is loading these untracked files into context (speculative — a prior session on this same repo hit context limits unexpectedly fast on a straightforward task)

Environment

• Claude Code with Opus 4.6
• macOS Darwin 24.6.0
• Git monorepo with multiple subprojects