Claude Code 2.1.191 adds /rewind and cuts CPU use 37%

• Claude Code 2.1.191 adds /rewind, which lets you resume a conversation from before /clear, according to ClaudeCodeLog's release post and the full changelog.
• Stopping a background agent from the tasks panel now sticks, with the release post highlighting the fix and the changelog calling out that agents no longer resurrect.
• Streaming output now batches text updates into 100 ms chunks, cutting CPU use by about 37 percent, per ClaudeCodeLog's summary and the changelog details.
• The patch is much broader than the headline items: the changelog also fixes hooks with comma-separated matchers, improves MCP retries and OAuth behavior, and trims long-session memory growth.

Anthropic packed 20 CLI changes into a patch that landed about nine hours after 2.1.190, and ClaudeCodeLog's follow-up diff post says the bundle grew by 707.4 kB while prompt files and prompt tokens stayed flat. The same diff post points to new model slugs such as claude-bg- and opus-on-pro-near-limit, which is catnip for anyone who watches Claude Code's internal surface area.

/rewind is the one net-new command in 2.1.191. The changelog describes it as a way to resume from before /clear, which turns a destructive reset into something closer to a checkpoint.

That matters most for long coding sessions where /clear used to be a hard boundary. The command gives Claude Code a native undo path for session context, instead of forcing users to reconstruct earlier state by hand.

The other workflow change is in task control. The changelog says background agents stopped from the tasks panel no longer restart, fixing behavior that could make a stop feel provisional.

The same release also patches agent-specific UI issues: the changelog says builtin slash commands such as /usage no longer get forwarded to background sessions as prompt text, and the agent panel no longer jumps by one row when scrolling past the overflow cap.

[Src:1|The changelog] ties the 37 percent CPU drop to coalescing streaming text updates to 100 ms. That is a small implementation detail with very visible terminal consequences, especially on long outputs where every repaint used to cost more.

The same section includes a cluster of session-state fixes:

• The changelog says scroll position no longer snaps to the bottom while reading earlier output during streaming.
• The changelog says long-session memory growth from the terminal output cache was reduced.
• The changelog says approvals in the /permissions Recently-denied tab now persist on close.
• The changelog says forceRemoteSettingsRefresh now works when set through MDM or file policy, and the fetch uses Cache-Control: no-cache.

[Src:1|The release notes] add three MCP-specific reliability changes: transient retries for capability discovery, one retry for OAuth discovery and token requests, and a better headless fallback that skips the browser popup and goes straight to a paste-the-URL prompt.

Meanwhile, ClaudeCodeLog's follow-up diff post spotted four new environment variables, BUF_BIGINT_DISABLE, CLAUDE_CODE_DD_ERROR_TRACKING_FLUSH_INTERVAL_MS, NODE_USE_ENV_PROXY, and MINIMATCH_TESTING_PLATFORM, plus model strings including claude-bg-, claude-code-error-tracking, o5-qn, o5-u:, and opus-on-pro-near-limit. None are documented features here, but they do show how much internal plumbing moved in what looks like a small point release.