v2.1.50 Claude Code Release Notes

Feb 20, 2026

Claude's Analysisby Sonnet 4.6

Opus 4.6 fast mode gains full 1M context; 7 memory leaks patched in long sessions; worktree isolation goes declarative; CLAUDE_CODE_SIMPLE now strips MCP, hooks, and attachments.

Changes

Total Changes (vs Average)

2.2×

Version Type

Patch

Release Focus

Bug Fixes

Day Since Prior Release

Release # This Month

#18 of 28

Bug Fix Ratio

56%

Post-Release Edits

—

Change Category

Ecosystem Impact

MCP appears in 4 of the last 10 releases; Plugins/Skills in 5. This release's deep memory and stability focus runs alongside sustained extensibility investment — suggesting the platform is hardening as the plugin surface area expands.

Key Themes

10Memory Leak Elimination Campaign|4Agent Worktree Isolation|2Opus 4.6 + 1M Context Expansion|2CLAUDE_CODE_SIMPLE Breaking Expansion|4MCP & Startup Reliability

May Help If You've Noticed

Your long Claude Code sessions slow down or crash over time as memory grows without bound

Added6 changes

•Added support for startupTimeout configuration for LSP servers
•Added WorktreeCreate and WorktreeRemove hook events, enabling custom VCS setup and teardown when agent worktree isolation creates or removes worktrees.
•Added support for isolation: worktree in agent definitions, allowing agents to declaratively run in isolated git worktrees.
•Added claude agents CLI command to list all configured agents
•Added CLAUDE_CODE_DISABLE_1M_CONTEXT environment variable to disable 1M context window support
•VSCode: Added /extra-usage command support in VS Code sessions

Improved3 changes

•Improved memory usage during long sessions by clearing internal caches after compaction
•Improved memory usage during long sessions by clearing large tool results after they have been processed
•Improved startup performance for headless mode (-p flag) by deferring Yoga WASM and UI component imports

Fixed14 changes

•Fixed a bug where resumed sessions could be invisible when the working directory involved symlinks, because the session storage path was resolved at different times during startup. Also fixed session data loss on SSH disconnect by flushing session data before hooks and analytics in the graceful shutdown sequence.
•Linux: Fixed native modules not loading on systems with glibc older than 2.30 (e.g., RHEL 8)
•Fixed memory leak in agent teams where completed teammate tasks were never garbage collected from session state
•Fixed CLAUDE_CODE_SIMPLE to fully strip down skills, session memory, custom agents, and CLAUDE.md token counting
•Fixed /mcp reconnect freezing the CLI when given a server name that doesn't exist
•Fixed memory leak where completed task state objects were never removed from AppState
•Fixed bug where MCP tools were not discovered when tool search is enabled and a prompt is passed in as a launch argument
•Fixed a memory leak where LSP diagnostic data was never cleaned up after delivery, causing unbounded memory growth in long sessions
•Fixed a memory leak where completed task output was not freed from memory, reducing memory usage in long sessions with many tasks
•Fixed prompt suggestion cache regression that reduced cache hit rates
•Fixed unbounded memory growth in long sessions by capping file history snapshots
•Fixed memory leak where TaskOutput retained recent lines after cleanup
•Fixed memory leak in CircularBuffer where cleared items were retained in the backing array
•Fixed memory leak in shell command execution where ChildProcess and AbortController references were retained after cleanup

Other2 changes

•CLAUDE_CODE_SIMPLE mode now also disables MCP tools, attachments, hooks, and CLAUDE.md file loading for a fully minimal experience.
•Opus 4.6 (fast mode) now includes the full 1M context window

Added6 changes

•Added support for startupTimeout configuration for LSP servers

•Added WorktreeCreate and WorktreeRemove hook events, enabling custom VCS setup and teardown when agent worktree isolation creates or removes worktrees.

•Added support for isolation: worktree in agent definitions, allowing agents to declaratively run in isolated git worktrees.

•Added claude agents CLI command to list all configured agents

•Added CLAUDE_CODE_DISABLE_1M_CONTEXT environment variable to disable 1M context window support

•VSCode: Added /extra-usage command support in VS Code sessions

Improved3 changes

•Improved memory usage during long sessions by clearing internal caches after compaction

•Improved memory usage during long sessions by clearing large tool results after they have been processed

•Improved startup performance for headless mode (-p flag) by deferring Yoga WASM and UI component imports

Fixed14 changes

•Fixed a bug where resumed sessions could be invisible when the working directory involved symlinks, because the session storage path was resolved at different times during startup. Also fixed session data loss on SSH disconnect by flushing session data before hooks and analytics in the graceful shutdown sequence.

•Linux: Fixed native modules not loading on systems with glibc older than 2.30 (e.g., RHEL 8)

•Fixed memory leak in agent teams where completed teammate tasks were never garbage collected from session state

•Fixed CLAUDE_CODE_SIMPLE to fully strip down skills, session memory, custom agents, and CLAUDE.md token counting

•Fixed /mcp reconnect freezing the CLI when given a server name that doesn't exist

•Fixed memory leak where completed task state objects were never removed from AppState

•Fixed bug where MCP tools were not discovered when tool search is enabled and a prompt is passed in as a launch argument

•Fixed a memory leak where LSP diagnostic data was never cleaned up after delivery, causing unbounded memory growth in long sessions

•Fixed a memory leak where completed task output was not freed from memory, reducing memory usage in long sessions with many tasks

•Fixed prompt suggestion cache regression that reduced cache hit rates

•Fixed unbounded memory growth in long sessions by capping file history snapshots

•Fixed memory leak where TaskOutput retained recent lines after cleanup

•Fixed memory leak in CircularBuffer where cleared items were retained in the backing array

•Fixed memory leak in shell command execution where ChildProcess and AbortController references were retained after cleanup

v2.1.50 Claude Code Release Notes

Changes in Claude Code v2.1.50

Added6 changes

Improved3 changes

Fixed14 changes

Other2 changes

v2.1.50 Claude Code Release Notes

Changes in Claude Code v2.1.50

Added6 changes

Improved3 changes

Fixed14 changes

Other2 changes