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Claude Code 2.1.208 リリースノート要約

[注意] セキュリティ・破壊的挙動の修正

• 危険なコマンドの実行防止: --dangerously-skip-permissions モードや auto モードにおいて、コマンド内の $(…)、バックティック、<(…) を含む致命的な削除（例: rm -rf ~）が実行される際に、確認プロンプトを表示するよう修正されました。
• 権限・認証エラーの早期発見: apiKeyHelper のスクリプトエラーが隠蔽される問題（無言のリトライ後に汎用401エラーになる）が修正され、3回以内にエラーが表示されるようになりました。

主な変更点・新機能

• スクリーンリーダーモード: アクセシビリティ向上のため、プレーンテキストレンダリングのスクリーンリーダーモード（claude --ax-screen-reader など）を追加。
• Vimモード拡張: vimInsertModeRemaps 設定を追加し、jj などの2ストロークキーを Escape に割り当て可能に。
• コーポレートランチャー対応: すべての Claude Code 自己起動において、指定のラッパー実行ファイルを経由する CLAUDE_CODE_PROCESS_WRAPPER を追加。
• UI/操作改善: マルチセレクトメニューやフルスクリーンモードでのマウスクリックをサポート。また、バックグラウンドエージェントのタスク進捗やUI再レンダリングの最適化により入力応答性が向上。

パフォーマンス・メモリ改善

• メモリ使用量の削減: ロングセッションでの複数のメモリリークを修正（MCP stderrの蓄積、LSPドキュメントの無制限オープン、画像データの保持など）。ファイル編集キャッシュを16 MB に制限。
• CPUオーバーヘッドの削減: ツール呼び出し時のCPU負荷を大幅に削減し（最大7倍高速化）、多くの権限ルールがあるセッションでの動作遅延を解消。
• ディスク/トランスクリプトの最適化: セッションのトランスクリプトサイズを最大79倍に圧縮し、チェックポイントのディスク使用量を制限。

主なバグ修正

• fast mode: モデル切り替え後に fast mode がオフになり、設定が復元されない問題を修正。
• 背景セッション: エージェントへの返信喪失や、アップデート後のデーモン起動失敗（"Couldn't start the background daemon"）、HTTP/2 GOAWAY によるクラッシュを修正。
• コンテキストウィンドウ誤表示: CLI自動更新後、一時的に200kにリセットされ「100% context used」と誤表示される問題を修正。
• トークン/出力関連: CLAUDE_CODE_MAX_OUTPUT_TOKENS 環境変数で指数表記（1e6など）の仮数だけが使われるバグ、claude -p の大規模出力切捨てを修正。
• ツール類の安定性: 巨大なMarkdownテーブルや、非常に長い1行を持つファイルの読み込み時のメモリ膨張・フリーズを修正。Edit、Read、Grep、Glob 各ツールの予期せぬエラーやクラッシュを修正。
• Bedrock連携: AWS SSO環境での認証エラーや、プロキシ変換時の誤解を招くストリーミングエラーを修正。

原文（Release Notes）

What's changed

• Added screen reader mode: opt-in plain-text rendering for screen reader users. Run claude --ax-screen-reader, set CLAUDE_AX_SCREEN_READER=1, or add "axScreenReader": true to settings.
• Added vimInsertModeRemaps setting: map two-key insert-mode sequences like jj to Escape in vim mode
• Added CLAUDE_CODE_PROCESS_WRAPPER: agent view and the background service now honor a corporate launcher by running every Claude Code self-spawn through a required wrapper executable
• Added mouse-click support for multi-select menus and "Other" input rows in fullscreen mode
• Fixed fast mode staying off after switching back to a model that supports it — it now restores automatically when enabled in settings
• Fixed replies typed to a background agent being lost when delivery fails — the text is now saved and delivered when the session restarts
• Fixed background-session attach failing permanently ("Couldn't start the background daemon") after an update replaced the binary a running claude agents process was launched from
• Fixed the context window (and auto-compact indicator) briefly resetting to 200k after the CLI auto-updates, causing a false "100% context used" when resuming long-context sessions
• Fixed supervised and background sessions crashing when a server closed an HTTP/2 connection with a GOAWAY while requests were in flight
• Fixed truncated stream-json/JSON output and missing result message when piping large responses from claude -p
• Fixed CLAUDE_CODE_MAX_OUTPUT_TOKENS and similar env vars silently using the mantissa of scientific-notation values (1e6 became 1)
• Fixed very large markdown tables stalling rendering or using excessive memory; tables over 200 rows show the first 200 with a "… N more rows" notice
• Fixed the Edit tool failing on files modified after reading when the target text still matches uniquely
• Fixed Read reporting empty files as "shorter than offset", Grep silently returning "No files found" for invalid regex patterns, Grep count mode under-reporting totals when paginated, and Glob crashing with an unclear error when the pattern, path, or working directory contained a null byte
• Fixed apiKeyHelper script failures being hidden behind a generic 401 after ~10 silent retries; the script's own error is now shown within 3 attempts
• Fixed Bedrock streaming requests failing with a misleading "Truncated event message received" when a gateway transforms the response — the error now names the content-type and points at the proxy
• Fixed /upgrade showing a login flow instead of the upgrade URL when the browser fails to open
• Fixed stream-json input killing the session on blank CRLF or whitespace-only lines from Windows-style SDK hosts
• Fixed headless stream-json sessions hanging permanently when a control_request carried a non-string set_model payload; the CLI now answers with an error response
• Fixed repeated "No completion record was found" notices on session resume — orphaned background tasks now collapse into a single summary
• Fixed Remote Control clients attaching to a terminal-hosted session not seeing background agents and workflow progress until a task started or stopped
• Fixed the Agent tool launching with no tools when a subagent's tools list resolves to nothing — it now returns a clear error naming the unrecognized entries
• Fixed /usage showing stale cached bars over fresher data, and /mcp not reclassifying placeholder servers after config edits
• Fixed "Change directory" in SDK hosts (e.g. Claude Desktop) failing with "A turn is in progress" on idle sessions that have a running background task
• Fixed the workflow save dialog showing ~/.claude/workflows/ instead of the CLAUDE_CONFIG_DIR location for user-scope saves
• Fixed /release-notes adding the viewed notes to the model's context — "Show all" previously injected the entire changelog into every subsequent request
• Fixed a memory leak in the agent view where pasted images were retained for the screen's lifetime after sending peek replies
• Fixed SDK sessions losing agents defined via the initialize request when a plugin refresh ran before the client attached
• Fixed several memory leaks in long sessions: MCP stdio server stderr accumulating up to 64 MB per server, LSP documents staying open indefinitely (now LRU with 50-doc cap), async hook output retained after backgrounding, and unbounded growth in headless/SDK sessions from large tool-result payloads
• Fixed a memory blowup when reading files with extremely long single lines using offset/limit — the read now returns a clean error instead of loading the whole line
• Fixed multi-second per-turn slowdowns in sessions with many permission deny/ask rules — rule matchers are now compiled once and cached
• Improved input responsiveness while agent task lists update — task updates no longer re-render the entire UI
• Reduced per-tool-call CPU overhead in print/SDK sessions with many MCP tools by caching tool-pool assembly (up to 7x faster tool rounds at high tool counts)
• Reduced memory usage by bounding the file edit read cache to 16 MB instead of pinning up to 1,000 full files
• Reduced session transcript size (up to 79x in edit-heavy sessions) and bounded checkpoint disk usage by pruning superseded file-history backups
• Reduced memory usage when resuming sessions with background agents or forks spawned from large conversations
• Completed background agents now stay listed in /tasks until cleanup instead of vanishing the moment they finish
• Attaching to a stopped background agent now shows its transcript immediately while the session warms up, instead of a blank "Session is starting" screen
• Background sessions: an older daemon no longer silently restarts workers spawned by a newer version onto the older binary
• Agent view: Ctrl+X now deletes renamed-branch worktrees, never destroys unpushed commits, keeps the session row when a worktree is kept, and reused worktree names reset to the current base
• Catastrophic removals (e.g. rm -rf ~) in commands containing $(…)/backticks/<(…) now prompt in --dangerously-skip-permissions and auto mode, matching the plain form
• /install-github-app and the /mcp settings menu no longer open in background sessions
• MCP servers configured with an empty URL now show as "not configured" in /mcp instead of a config error
• /usage now shows your last-known usage bars with an "as of" note when the usage endpoint is rate-limited, instead of an error screen
• Fixed Bedrock auth failing with "Session token not found or invalid" for AWS SSO profiles whose sso_region differs from the Bedrock region (2.1.207 regression)