Claude Code Week 17 (April 20–24, 2026): /ultrareview Public Preview, Session Recap, Custom Themes, Web Redesign

Anthropic's Week 17 update (April 20–24, 2026, v2.1.114 → v2.1.119) is a quieter polish week for Claude Code after Week 16's Opus 4.7 launch. Four headline items: /ultrareview opens to public research preview, session recap becomes automatic when you return to an unfocused terminal, custom themes ship as a first-class feature you can build and distribute via plugins, and Claude Code on the web gets a redesign that matches the desktop app.

TL;DR

• /ultrareview is now a public research preview: a fleet of cloud bug-hunting agents reviews your branch or a PR; findings land back in the CLI or Desktop.
• Session recap shows a one-line summary of what happened while a terminal was unfocused; run /recap on demand or turn off auto-recap from /config.
• Custom themes (v2.1.118): build named color themes from /theme, hand-edit JSON in ~/.claude/themes/, or ship them in a plugin.
• Claude Code on the web redesign: sessions sidebar, drag-and-drop layout, refreshed routines view.
• /cost and /stats merged into /usage; old names still work.
• Vim visual mode in the prompt input (v for char selection, V for line selection).

Quick Answer

Update Claude Code (claude update) and run /ultrareview before your next critical merge — it's the single highest-leverage feature this week. Open /theme to try out custom themes (or pick "Auto (match terminal)" added in Week 16). And if you bounce between several sessions, leave automatic session recap on so you don't lose context when you tab back.

What Shipped in Week 17

/ultrareview Goes Public

/ultrareview arrived in Week 16 and opened to public research preview in Week 17. It runs a fleet of bug-hunting agents in the cloud against your branch or a PR, with an adversarial critique pass to verify each finding, and the findings land back in the CLI or Desktop automatically. Anthropic's specific guidance: run it before merging critical changes such as auth or data migrations.

Review the branch you're on:

> /ultrareview

Or point it at a PR number:

> /ultrareview 1234

This sits next to /ultraplan from Week 15 as the second cloud-side ultra workflow: instead of holding your terminal open while a long-running agent works, you offload it and get the result back as a transcript message. For the broader landscape of automated review, see our AI code review tools roundup.

Session Recap: Catch Up Without Re-reading the Scroll

Session recap shows a one-line summary of what happened while a terminal was unfocused. If you're running several Claude sessions at once — one watching CI, one running a long refactor, one in plan mode — recap is what you read when you tab back instead of scrolling through tool calls.

Generate one on demand, or turn the automatic recap off from /config:

> /recap

The automatic version originally appeared in Week 16's "other wins" list and became prominent enough in Week 17 to graduate to a headline feature.

Custom Themes

Custom themes (v2.1.118) let you build and switch between named color themes directly from /theme, or hand-edit JSON files in ~/.claude/themes/. Each theme picks a base preset and overrides only the tokens you care about, so you don't have to redefine an entire palette to tweak a few colors. Plugins can ship themes too, so a team can standardize on a shared look.

> /theme

Combined with Week 16's "Auto (match terminal)" option that follows your terminal's dark/light mode, terminal aesthetics in Claude Code are now a first-class configuration surface.

Claude Code on the Web: Redesign

The redesign of claude.ai/code brings the web client in line with the redesigned desktop app:

• Sessions sidebar for moving between active and recent sessions
• Drag-and-drop layout so you can rearrange panes
• Refreshed routines view that matches the new chrome — useful since Routines (shipped in Week 16) now drive a non-trivial share of cloud agent work
• Performance and reliability: key parts were rebuilt for quicker responses

If you're new to Claude Code on the web, our Week 15 update covers the cloud workflows (/ultraplan, /autofix-pr) that drove its growth, and the web client is where most of those workflows are reviewed.

Other Notable Wins in Week 17

A long tail of polish, much of it useful:

• Vim visual mode in the prompt input: press v for character selection or V for line selection, with operators and visual feedback.
• Hooks can call MCP tools directly via type: "mcp_tool", so a hook can hit an already-connected server without spawning a process.
• /cost and /stats merged into /usage; the old names still work as typing shortcuts that open the relevant tab.
• /config changes (theme, editor mode, verbose, and similar) now persist to ~/.claude/settings.json and follow the same project/local/policy precedence as other settings.
• Forked subagents can be enabled on external builds with CLAUDE_CODE_FORK_SUBAGENT=1 — a fork inherits your full conversation context instead of starting fresh.
• Default effort level for Pro and Max subscribers on Opus 4.6 and Sonnet 4.6 is now high (was medium).
• Native macOS and Linux builds replace the Glob and Grep tools with embedded bfs and ugrep available through Bash, for faster searches without a separate tool round-trip.
• --from-pr now accepts GitLab merge request, Bitbucket pull request, and GitHub Enterprise PR URLs in addition to github.com.
• Auto mode: include "$defaults" in autoMode.allow, soft_deny, or environment to add custom rules alongside the built-in list instead of replacing it.
• New claude plugin tag command creates release git tags for plugins with version validation.
• Opus 4.7 sessions now compute against the model's native 1M-token context window, fixing inflated /context percentages and premature autocompaction.
• /resume on large sessions is up to 67% faster and now offers to summarize stale, large sessions before re-reading them.

How This Compares to Other Agents

For deeper context, see our Claude Code vs Aider guide, the cursor-vs-claude-code">Cursor vs Claude Code comparison, and the Claude Code tool page.

Sources

• Claude Code "What's New" — Week 17 (official): code.claude.com/docs/en/whats-new/2026-w17
• Claude Code "What's New" index: code.claude.com/docs/en/whats-new
• Claude Code changelog v2.1.114 → v2.1.119: code.claude.com/docs/en/changelog
• Ultrareview guide: code.claude.com/docs/en/ultrareview
• Interactive mode — session recap: code.claude.com/docs/en/interactive-mode#session-recap
• Terminal config — create a custom theme: code.claude.com/docs/en/terminal-config#create-a-custom-theme
• Claude Code on the web: code.claude.com/docs/en/claude-code-on-the-web

For more on recent Claude Code shipments, see our Week 15 update and Week 16 update. For current model guidance, see our Claude Opus 4.6 vs Opus 4.5 comparison and the beginner's guide to AI models.