Claude Code v2.1.246 Fixes Diff Rendering, MCP Interruptions, and More

Claude Code v2.1.246 is out, focused on fixing a batch of bugs that plagued fullscreen, background sessions, plugins, and MCP integrations. The release also adds a startup warning for risky Bash allow rules and an Auto mode tab in /permissions.

Performance Fixes

One severe issue: transcripts with diffs containing very long single lines (like base64 strings) slowed down dramatically. These lines now render truncated with a marker. Fullscreen mode also had issues where resizing the terminal showed a blank transcript until the next keypress, and scrolling erratically when positioned at an earlier message—both fixed. /stats heatmap alignment in timezones east of UTC is corrected too (Sunday's count was showing under Monday).

Bash Allow Rules Warning

A new startup warning flags Bash allow rules with a wildcard before the subcommand, e.g., Bash(git * main). Such rules can match options inserted before the subcommand, introducing security risks. The warning helps you avoid unintended matches.

MCP and Headless Sessions

MCP tool calls interrupted by an incoming message in headless/remote sessions are now reported as an explicit interrupted error instead of a misleading "completed with no output". Also fixed: MCP tool arguments being sent as JSON strings when the parameter schema is empty ({}), now they preserve their real type.

Background Sessions and Worktrees

Background sessions failing to open after 45 seconds when the starting directory was deleted, machine slept, or host was slow are fixed. Also, a race condition where another Claude Code process was re-installing the npm package caused EACCES errors—resolved. The background retention sweep no longer removes git worktrees you created yourself under .claude/worktrees/ when an old session record pointed at them.

Plugins and Themes

Plugin cache no longer creates duplicate SHA-named directories, and plugin skills with the <plugin>: prefix in frontmatter name show it doubled (e.g., /plugin:plugin:skill)—fixed. claude plugin update now works with bare names, plugin installs handle UTF-8 BOM in plugin.json, and /reload-plugins reports skills correctly. Hook error messages now resolve ${CLAUDE_PLUGIN_ROOT} properly. Custom theme diff colors are respected, and /rename no longer changes the prompt border color to cyan.

Other Notable Fixes

• Keyboard bindings with unknown action names are now skipped, logging a warning under --debug, instead of deadening the key.
• /fork from an already-forked or backgrounded session starts with the full conversation, not empty.
• Prompts beginning with /-- (like Lean doc comments) are now sent to Claude instead of rejected as unknown slash commands.
• The @ file picker closes when typed text stops matching a real path.
• Status line cost/duration no longer resets after visiting agents view.
• Fullscreen mode no longer moves focus to the control under the pointer on click.
• Dynamic workflow restarts asking before restarting finished subagents, with count.
• Auto mode tool calls no longer denied as "temporarily unavailable" on large sessions—safety-check deadline scales with prompt size.

If you're on an earlier version, upgrade to get these stability improvements.