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Claude Code 2.1.172 リリースノート要約

⚠️ 重要な修正（動作・セキュリティ関連）

• セッティングの分離バグ修正: バックグラウンドエージェントが、別ディレクトリのプロジェクト設定（.mcp.json の承認や信頼情報など）を誤って読み込む可能性があった問題を修正しました。

主な変更点・新機能

• サブエージェントのネスト化: Sub-agentsが自身のSub-agentsを生成可能になりました（最大5階層まで）。
• Amazon Bedrockの連携強化: AWS_REGION未設定時、~/.aws設定ファイルからリージョンを自動読み込みするようになりました。/statusで取得元を確認可能です。
• UI/UXの改善: /pluginにプラグイン検索バーを追加。長時間の会話におけるパフォーマンス向上とアイドル時のCPU使用率削減（不要な再描画の排除など）。
• 外部ツール連携の最適化: Claude in Chromeのツール読み込みを個別から一括呼び出しに変更し高速化。

主なバグ修正

• コンテキスト超過の解消: 1Mコンテキスト利用時のクレジット不足で、セッションが完全にスタックする問題を修正（標準コンテキスト上限へ自動圧縮するよう挙動を変更）。
• モデル選択のバグ修正: /modelピッカーにおける組織制限の迂回や、Bedrockで提供外モデルが選択可能になる問題、モデルIDのサフィックス重複（例: [1M][1m]）などを修正。
• 権限ルールのバグ修正: WebFetch(domain:*.example.com)のサブドメ不一致や、Read(secrets-*/config.json)の中間ワイルドカードが起動時に拒否される問題を修正。
• その他の挙動修正: 複数画像処理時の繰り返しエラー解除、バックグラウンドでのステータス表示のスタック解消、メモリストアの検知不良の解消など。
• VSCode: PowerShellツール呼び出しの生JSON表示を修正し、出力からANSIエスケープコードを除去するよう修正。

原文（Release Notes）

What's changed

• Sub-agents can now spawn their own sub-agents (up to 5 levels deep)
• Amazon Bedrock now reads the AWS region from ~/.aws config files when AWS_REGION isn't set, matching AWS SDK precedence; /status shows where the region came from
• Added a search bar when browsing a marketplace's plugins in /plugin
• Added model attribute to the claude_code.lines_of_code.count OTEL metric
• Fixed sessions using 1M context without usage credits getting permanently stuck — the session now automatically compacts back under the standard context limit
• Fixed a repeating "an image in the conversation could not be processed and was removed" error when the conversation contained multiple images
• Fixed the agents view keeping a session under Working with a busy spinner for up to 30 seconds after the worker replied
• Fixed background agents potentially reading another directory's project settings (.mcp.json approvals, trust) when dispatched onto a pre-warmed worker
• Fixed background-session attach failing with EAUTH for sessions started on an older version after the daemon auto-updated
• Fixed a background sub-agent staying stuck as "active" in the agent panel after a nested agent it spawned was stopped
• Fixed /model suggestions in the claude agents dispatch input rendering with a misleading slash prefix and showing models disabled for your org
• Fixed availableModels restrictions not being applied to subagent model overrides, the agent dispatch model picker, and the advisor model
• Fixed availableModels allowlists hiding the /model picker's Opus and Sonnet 1M rows when entries use version-specific IDs like claude-opus-4-8
• Fixed the /model picker on Bedrock offering models the provider doesn't serve — selecting one silently switched the session model and lit the selection marker on multiple rows
• Fixed model IDs getting a doubled 1M-context suffix (e.g. [1M][1m]) when ANTHROPIC_DEFAULT_OPUS_MODEL already includes one
• Fixed opusplan model setting not shipping with 1M context in plan mode for entitled users; the opusplan[1m] workaround now also correctly switches to Opus in plan mode
• Fixed WebFetch(domain:*.example.com) wildcard domain rules never matching subdomains in allow, deny, and ask position, and file permission rules with mid-pattern wildcards (e.g. Read(secrets-*/config.json)) being rejected at startup
• Fixed up-arrow prompt history showing the main agent's prompts while a subagent's chat tab is open
• Fixed memory recall not finding mounted team memory stores (CLAUDE_MEMORY_STORES) in remote sessions
• Fixed workflow validation rejecting scripts whose prompt strings or comments merely mention Date.now()/Math.random()
• Disable mouse tracking on Windows consoles that don't fully support it
• Fixed the /plugin marketplace list losing its cursor after backing out of a long plugin list, and Esc from the plugin browser returning to the wrong tab
• Improved performance in long conversations by removing redundant message normalization and avoiding full message-history transforms when streaming tool-use state is unchanged
• Reduced idle CPU usage: /goal status chip no longer re-renders the terminal at 5 Hz while idle, and fewer UI re-renders while subagents run in parallel
• Improved Claude in Chrome tool loading: browser tools now load in a single batched call instead of one per tool
• Improved the non-interactive Usage Policy refusal message to suggest starting a new session or changing your model
• /code-review now keeps the ultra option visible when you're not signed in to claude.ai, with an explanation that the cloud review requires a claude.ai account
• Shortened the Remote Control footer indicator to "/rc active" and hid it on narrow terminals
• Stopped promoting /loop in remote sessions, where pending loops don't keep the container alive
• [VSCode] Fixed PowerShell tool calls rendering as raw JSON instead of a proper command display and permission dialog, and stripped ANSI escape codes from displayed shell output