Claude Code 2.1.191: /rewind After /clear, Background Agent Fixes, MCP

TL;DR: Claude Code 2.1.191 dropped June 25, 2026 (@ClaudeCodeLog / @marc_krenn). Headline features: /rewind resumes context from before /clear, background agent stops are permanent, ~37% lower CPU during streaming (100ms coalescing), comma-separated hook matchers fixed, and a pile of MCP reliability improvements. Twenty CLI changes total.

Highlights at a glance

/rewind: recover from /clear

The biggest workflow fix in 2.1.191:

Added /rewind support for resuming a conversation from before /clear was run.

Before: /clear (aliases /reset, /new) wiped context. If you cleared too aggressively, you relied on /resume for a saved session — not the in-flight thread.

After: /rewind rolls back to a checkpoint before the clear, restoring prior context so the session continues.

This sits alongside existing rollback tools:

Deep dive: Claude Code commands reference · Checkpoint restore guide.

Background agents: stops stick

Fix: Background agents stopped from the tasks panel no longer restart — stopping is permanent.

If you run parallel work via /fork, /agents, or /tasks, a stop that silently undid itself was dangerous (duplicate edits, double bash). 2.1.191 closes that hole.

Related: claude agents no longer sends builtin slash commands like /usage to background sessions as raw prompt text — you get a hint instead.

Performance: 37% less CPU while streaming

Two related improvements:

1. Coalesce text updates to 100ms → ~37% CPU reduction during streaming responses
2. Reduced long-session memory growth from terminal output cache
3. Scroll fix — reading earlier output no longer jumps you to the bottom mid-stream

For developers running sound and traffic-light hooks on long agent sessions, lower CPU and stable scroll make unattended monitoring less painful.

Hooks: comma-separated matchers fixed

Bug: Hooks with matchers like "Bash,PowerShell" silently never fired.

Fix in 2.1.191: Multi-tool matchers parse correctly.

If you copied hook recipes from forums and wondered why nothing ran, update first, then audit ~/.claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash,PowerShell",
        "hooks": [{ "type": "command", "command": "echo triggered" }]
      }
    ]
  }
}

MCP improvements

Connect tools: Claude Code MCP guide.

Permissions, sandbox, and enterprise

• /permissions Recently-denied tab — approving a denial now persists on close (was silently discarded)
• Sandbox network dialog — hosts allowed with "Yes" are remembered for the session
• /voice — when disabled by org policy, message explains the restriction (not generic "not available")
• Managed settings — forceRemoteSettingsRefresh works via MDM/file policy; fetch sends Cache-Control: no-cache

Other fixes (selected)

• /login URL — no longer truncated when wrapped in Windows Terminal
• Cmd+click links — fixed in Ghostty over ssh/tmux fullscreen
• Agent panel — no longer jumps one row when scrolling roster past overflow cap
• Image placeholders — job rows show [Image #N] not full filesystem paths
• Welcome splash — no longer overflows default 80×24 macOS Terminal
• Vim / search — hints how to reach slash commands from NORMAL mode

New env vars and models (CLI surface)

Per @ClaudeCodeLog extended thread, 2.1.191 also adds:

Environment variables: BUF_BIGINT_DISABLE, CLAUDE_CODE_DD_ERROR_TRACKING_FLUSH_INTERVAL_MS, NODE_USE_ENV_PROXY, MINIMATCH_TESTING_PLATFORM

Model aliases (internal/flags): claude-bg-, claude-code-error-tracking, o5-qn, o5-u:, opus-on-pro-near-limit

Treat model slug additions as feature-flag plumbing unless documented on code.claude.com.

How to update

# If installed via npm/homebrew — follow your usual upgrade path
claude --version   # confirm 2.1.191+

# Or use Claude Code's built-in update mechanism per official docs

Changelog source: @ClaudeCodeLog (unofficial, tolerated bot) · full history in linked GitHub repo.

Related reading

• Claude Code desktop flexible panes + persistent /diff (Sept 2026) — multi-session layouts that match parallel/background agent work
• screenpipe — desktop work memory via MCP (Jul 2026)
• Claude Code commands — full reference
• /rewind on slash commands registry
• Restore checkpoints (ESC × 2)
• Hooks automation guide
• Sound + traffic-light approval alerts
• /goal long-running agents

Changelog items sourced from @ClaudeCodeLog posts on June 25, 2026. Verify behavior on your installed version — patch details may vary by platform.