Claude Code 2.1.121: Plugin Pruning, MCP AlwaysLoad, and Two Multi-GB Memory Leak Fixes

Claude Code v2.1.121 is out as of today, April 28. This one is heavier than the usual incremental release: two separate multi-gigabyte memory leaks are fixed, MCP server management gets a new option, and the plugin system picks up a pruning command.

Plugin Pruning

The new claude plugin prune command removes orphaned auto-installed plugin dependencies that get left behind when you uninstall plugins. You can also use plugin uninstall --prune to cascade deletions at uninstall time rather than cleaning up separately.

If you’ve been installing and removing plugins for a while, you may have accumulated dependencies that nothing actually needs. This addresses that.

MCP: alwaysLoad Option

MCP servers now support an alwaysLoad configuration option. When set to true, all tools from that server skip Claude Code’s tool-search deferral system and are immediately available without being fetched first.

The deferral system helps performance when you have many MCP tools loaded — it keeps infrequently-used tools out of the active context until they’re needed. But for servers you rely on constantly, the deferral adds latency. alwaysLoad lets you opt specific servers out of that behavior.

Type-to-Filter in /skills

The /skills command now has inline search. Type to filter skills in long lists without scrolling. If you’ve accumulated many skills, this removes the friction of finding a specific one when you only roughly remember its name.

PostToolUse Hooks Can Replace All Tool Output

The PostToolUse hook can now replace tool output for any tool via hookSpecificOutput.updatedToolOutput. Previously this capability was limited to MCP tools only. This makes the hook system considerably more flexible for anyone building Claude Code automations or customized tool behaviors.

Scrollable Dialogs

Terminal dialogs that overflow the screen are now scrollable. Arrow keys, PgUp/PgDn, Home/End, and mouse wheel all work. The previous behavior — dialogs that ran off the bottom with no way to reach the lower content — was a real limitation for anything with long content.

Two Memory Leak Fixes

The more significant changes in this release are on the bug fix side.

Processing many images in a session was causing unbounded memory growth, with RSS climbing into the multi-gigabyte range. That’s been fixed.

Separately, the /usage command was leaking approximately 2GB of memory on machines with large transcript histories. Both issues could make long sessions unusable, particularly for users running image-heavy workflows or reviewing extensive session histories.

Other Fixes

A few other things worth knowing:

The Bash tool would become permanently unusable if its start directory was deleted during a session. That’s fixed.
--resume was crashing on startup in external builds. Fixed.
Microsoft 365 MCP OAuth was failing with a duplicate prompt parameter error. Fixed.
Scrollback duplication in tmux and other multiplexers is resolved.
Claude.ai MCP connectors were disappearing on transient auth errors. Now they auto-retry up to 3 times before surfacing an error.
NO_PROXY was not being respected for all HTTP clients. Fixed.
The “Always allow” permission rules weren’t surviving worker restarts in remote sessions. Fixed.

The full changelog is at github.com/anthropics/claude-code/releases.

Sources: GitHub Releases, Releasebot