Claude Code 2.1.216 Fixes Quadratic Slowdown in Long Sessions
Claude Code 2.1.216 fixes a bug where message normalization cost grew quadratically with turn count, causing multi-second stalls and slow resumes in long sessions.
What it is
The latest patch release of Claude Code, Anthropic's CLI coding agent, following closely on the heels of 2.1.215.
What it does
It fixes message normalization that scaled quadratically with the number of turns in a session, which was causing multi-second stalls and slow resumes on long-running conversations. It also adds a sandbox.filesystem.disabled setting to skip filesystem isolation while keeping network egress control, fixes auto mode wrongly denying commands after an OAuth token rotated mid-session, and stops AskUserQuestion from telling Claude to continue when a free-text answer actually asked it to wait or explain.
Why it matters
Anyone running Claude Code for hours on the same task was quietly eating an ever-growing tax on every turn. This is the kind of fix that makes long agentic sessions actually usable instead of degrading into molasses the longer you work.
How to use it
Update via your normal Claude Code update path; the fix is automatic, no config needed. If you want to skip filesystem sandboxing while still enforcing network controls, set sandbox.filesystem.disabled in your settings.
Claude Code v2.1.209: fix for blocked dialogs in background agent sessions
Claude Code 2.1.209 reverts an overly broad guard that had been blocking /model and other dialogs inside claude agents background sessions.
Claude Code 2.1.215 makes /verify and /code-review opt-in again
Claude Code 2.1.215 stops automatically invoking the /verify and /code-review skills, requiring users to run them explicitly with the /verify or /code-review commands.
Claude Code 2.1.214 closes a PowerShell permission bypass
Claude Code 2.1.214 fixes four permission-check bugs, including nested-directory allow rules matching too broadly and a bypass in Windows PowerShell 5.1 sessions.