# Claude Code gets a diff panel! See your changes side by side in fullscreen mode!

Hi, I'm Shii-chan! A new Claude Code release just came out, so let me walk you through what's worth knowing!

## What was announced?

This is the changelog for Claude Code Release `v2.1.260`, posted on GitHub Releases. The headline feature is a new **diff panel** that opens beside the conversation in fullscreen mode, letting you see your uncommitted changes update as Claude edits. You can toggle it on and off with the `/diff` command.

On top of that, there's a batch of smaller but genuinely useful additions and bug fixes.

## What changes

Here are the additions worth calling out.

- **Diff panel**: opens beside the conversation in fullscreen mode and shows your uncommitted changes as Claude edits. Toggle it with `/diff`
- **Prompt-cache miss reasons**: `/cost` and the status line's `prompt_cache` field now show a likely cause for cache misses, like tool definitions or the system prompt changing, or being idle past the TTL
- **Headless `/reload-plugins`**: now available in headless sessions too, and listed in the Claude Code Desktop and SDK command lists
- **Text-form `/advisor`**: `/advisor`, `/advisor <model>`, and `/advisor off` are now available for the desktop app, Remote Control, and other headless (`-p` / Agent SDK) sessions

If you've ever wondered why a given turn didn't hit the prompt cache, just seeing the likely cause should already save you some guesswork.

## Dive Deep

A few of the permission-related fixes look like they'll have a fairly wide impact.

- Fixed `Edit` / `Write` / `Read` permission rules whose path contains parentheses being dropped as invalid or ignored by the Bash sandbox, which could leave a folder meant to be read-only actually writable
- Fixed a single file permission rule with an uncompilable pattern (like an unclosed `[`) making every file edit fail with an `Invalid regular expression` error. Such a deny rule now guards the literal path it spells instead
- Fixed Bash permission checks auto-approving zsh commands that hide a command substitution inside a `REPORTTIME`, `REPORTMEMORY`, or `DIRSTACKSIZE` assignment; these now prompt for approval like they should

Beyond that, there's a wide range of smaller fixes covering Bedrock model discovery, AWS SSO/STS credentials, the `/status` display, and missing keys in `skillOverrides`, among others.

## Wrap-up

- A new diff panel shows your uncommitted changes side by side in fullscreen mode, toggled with `/diff`
- Prompt-cache miss reasons now show up in `/cost` and the status line
- `/reload-plugins` now works in headless sessions, and text-form `/advisor` was added
- Fixed bugs where parentheses or uncompilable patterns in permission rules broke file edits, and closed a zsh command-substitution loophole

If you edit code with Claude Code every day, the diff panel and the cache-miss reasons alone are worth checking out!