[FEATURE]

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The compact diff preview in Claude Code's edit review pane only shows the changed region of a file. For larger files, this makes it impossible to assess an edit in full context — you cannot see surrounding code, understand the structural impact, or verify consistency with the rest of the file before deciding to accept or reject.

The only current workaround is to accept the change first, then open Source Control (Ctrl+Shift+G) to view the full diff retrospectively. This removes the approval gate before the review is complete, which defeats the purpose of the review step.

Proposed Solution

Add a compound button to the edit review pane — a primary action with a dropdown arrow — offering two options:

• Open in new tab: opens the pending diff in a VS Code native diff editor tab within the current window, showing the full file before/after the change.
• Open in new window: opens the diff in a separate VS Code window, useful for multi-monitor setups or when the current window is crowded.

The button should sit alongside the existing Accept/Reject controls and should not auto-dismiss the pane — the user should still be able to accept or reject from the pane after reviewing in the full editor.

Alternative Solutions

Current workaround: accept the change, then open Source Control to view the full diff against the last committed state. This is backwards — it removes the approval gate before the review is complete.

A related request, #11411, proposed a simple "Open in Editor" button and was closed as not planned. This request differs in two ways:

1. It adds a new-window option specifically to support multi-monitor workflows.
2. It frames the interaction as a compound button (primary action + dropdown) to keep the review pane UI tidy rather than adding multiple buttons.

Priority

Low - Nice to have

Feature Category

Interactive mode (TUI)

Use Case Example

1. Claude proposes an edit to a 300-line service class, changing a constructor signature.
2. The review pane shows a 20-line diff fragment — enough to see the change, but not enough to confirm that all usages within the same file are still consistent.
3. I click the compound button → "Open in new tab".
4. VS Code opens a full side-by-side diff. I scroll through all 300 lines, confirm nothing downstream is broken, and return to the pane.
5. I click Accept, confident the change is safe.

Without this button I either accept blindly and check after, or manually open the file in a second editor to compare — neither is as ergonomic.

Additional Context

• Related closed issue: #11411 — our request focuses on an on-demand button rather than a global setting, which may be a lighter implementation path and avoids the behavioral change that led to #11411 being declined.
• The "open in new window" option covers a use case #11411 didn't address: developers on multi-monitor setups who want the full diff on a second screen while keeping the review pane visible on the primary.
• The compound/split button pattern is already familiar in VS Code (e.g. the "Open to the Side" button in the editor tab bar) and in GitHub's own PR review interface.