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1> ## Documentation Index
2> Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt
3> Use this file to discover all available pages before exploring further.
4
5# Week 36 · August 31 – September 4, 2026
6
7> Switch to Claude Fable 5.1, let computer use run in the background on Desktop, and watch Claude's edits in a live /diff panel.
8
9Releases [v2.1.251 → v2.1.261](https://code.claude.com/docs/en/changelog.md#2-1-251)
104 features · August 31 – September 4
11
12Claude Fable 5.1
13new model
14
15Claude Fable 5.1 is available in Claude Code with a 1M-token context window, and the `fable` alias now selects it. In Claude apps gateway sessions, `fable` still selects Fable 5. If your gateway serves Fable 5.1, run `/model claude-fable-5-1`. Requires v2.1.257 or later.
16
17Switch the current session to Fable 5.1 and save it as your default:
18
19```text Claude Code theme={null}
20> /model fable
21```
22
23On the Anthropic API, the picker lists Fable only once the server reports it available for your organization, but typing `/model fable` checks with the server directly.
24
25[Work with Fable](https://code.claude.com/docs/en/model-config.md#work-with-fable)
26
27Computer use runs in the background on Desktop
28Desktop
29
30On macOS, computer use in the Claude Code Desktop app now works in the background: Claude sees and acts in the apps you've approved while you keep working. Background computer use is in beta on Pro and Max plans.
31
32
33
34[Let Claude use your computer](https://code.claude.com/docs/en/desktop.md#let-claude-use-your-computer)
35
36Live diff panel in fullscreen rendering
37v2.1.260
38
39In fullscreen rendering, `/diff` now opens a panel beside the conversation instead of a viewer you have to close. The panel lists the changed files with their added and removed line counts and refreshes each time Claude edits a file or runs a shell command. Select lines in the panel with the mouse to attach them to your next prompt.
40
41<video autoPlay muted loop playsInline src="https://mintcdn.com/claude-code/f9HTZGyMtxIFOUgt/images/whats-new/diff-panel.mp4?fit=max&auto=format&n=f9HTZGyMtxIFOUgt&q=85&s=9d7553c19e7f227891cd95f1f59d796d" />
42
43With fullscreen rendering on, inside a git repository, and in a terminal at least 110 columns wide, toggle the panel:
44
45```text Claude Code theme={null}
46> /diff
47```
48
49Run `/diff` again or click the `✕` in its header to close it.
50
51[Diff panel](https://code.claude.com/docs/en/interactive-mode.md#diff-panel)
52
53Find unused skills with /skill-doctor
54CLI
55
56`/skill-doctor` shows what each of your skills costs in context and how often it gets used, so you can decide which ones to turn off. Every skill in the [skill listing](https://code.claude.com/docs/en/skills.md#skill-descriptions-are-cut-short) adds to your context on every turn, whether or not Claude ever uses it. Requires v2.1.252 or later and isn't available in sessions that skip [feature-flag fetching](https://code.claude.com/docs/en/env-vars.md#features-that-need-feature-flag-fetching).
57
58Run it in an interactive session to open the report in the `/plugin` manager's **Stats** tab:
59
60```text Claude Code theme={null}
61> /skill-doctor
62```
63
64In non-interactive mode with `-p`, Claude Code prints the report as text instead.
65
66[Find unused skills](https://code.claude.com/docs/en/skills.md#find-unused-skills)
67
68Other wins
69
70A [`PreModelSwitch`](https://code.claude.com/docs/en/hooks#premodelswitch) hook can block a model switch you request, and a [`PostModelSwitch`](https://code.claude.com/docs/en/hooks#postmodelswitch) hook can add context for Claude after the session's model changes[`/cost`](https://code.claude.com/docs/en/costs#prompt-cache-statistics) adds a `Prompt cache (main)` line: the share of input tokens served from cache, the cache misses, whether the cache is warm, and a likely cause for the last miss when Claude Code can name one. Status line scripts get a matching `prompt_cache` objectOrganizations can list HTTP and SSE MCP servers under the [`managedMcpServers`](https://code.claude.com/docs/en/managed-mcp#provide-servers-through-managed-settings) managed setting to give them to every user, in addition to the servers that users add on their own`/effort` and the `/model` picker now [save a separate effort level for each model](https://code.claude.com/docs/en/model-config.md#adjust-effort-level); press `s` instead of `Enter` to apply a level to the current session onlyBy default, the auto mode classifier [now also blocks](https://code.claude.com/docs/en/permission-modes.md#what-the-classifier-blocks-by-default) actions such as requesting credentials from the cloud instance-metadata endpoint or connecting to sibling containers that Claude didn't startIn auto mode, Claude Code asks you before Claude [first reads a file outside your working directories](https://code.claude.com/docs/en/permission-modes.md#first-read-outside-the-working-directories), with an option to block such reads from then onRaise [`bashOutputMaxChars`](https://code.claude.com/docs/en/settings-reference#bashoutputmaxchars) and [`taskOutputMaxChars`](https://code.claude.com/docs/en/settings-reference#taskoutputmaxchars), up to 128,000 characters, so Claude receives more of the output from a successful command or background task inlineThe prompt's [word-editing shortcuts follow readline](https://code.claude.com/docs/en/interactive-mode.md#make-ctrl-w-delete-back-to-whitespace) for everyone, and the `keybindingFlavor` setting no longer has any effect. `Ctrl+W` deletes back to the previous whitespace, and `Alt+B`, `Alt+F`, and `Alt+D` treat punctuation such as `/` and `.` as word breaksIf you set `defaultMode` to `"bypassPermissions"` in a project's `.claude/settings.json` or `.claude/settings.local.json`, it [no longer takes effect](https://code.claude.com/docs/en/permission-modes.md#which-mode-a-session-starts-in) and the session starts in Manual mode; set `"bypassPermissions"` in user or managed settings instead, or pass `--permission-mode`Seat-based Enterprise plans now [default to Opus 5](https://code.claude.com/docs/en/model-config.md#default-model-setting)In the VS Code extension, click the model name at the bottom of the prompt box to [open the model picker](https://code.claude.com/docs/en/vs-code.md#use-the-prompt-box)In the VS Code extension, select **Output styles** in the command menu's Customize section to [pick an output style](https://code.claude.com/docs/en/vs-code.md#use-the-prompt-box), including your custom ones
71
72[Full changelog for v2.1.251–v2.1.261 →](https://code.claude.com/docs/en/changelog.md#2-1-251)