Wednesday roundup: 21 Oct 2026

This fixes the bug in 2.1.304 that made every request fail on Vertex, Bedrock and gateways that reject tool search. Claude Code now retries without tool search.

A new sandbox.allowNestedUserNamespaces setting lets sandboxed Linux commands run Chromium or rootless podman. It also weakens the sandbox's file protections.

Unattended retry mode can now notice when a usage limit lifts early, using CLAUDE_CODE_RETRY_WATCHDOG_USAGE_LIMIT_RECHECK_MS.

Worktree fixes: new worktrees in bare repos now start from the default branch, and unchanged subagent worktrees are cleaned up. Resuming a workflow no longer re-runs finished pipeline() and parallel() agents.

allowedMcpServers no longer filters stdio servers in managed-mcp.json that use ${VAR} only in env. A server left off the allowlist can now load after upgrading. Use deniedMcpServers to keep it blocked.

You can now choose a 12-hour cache on the Responses API, so shared instructions, tools and context stay cached even when requests are hours apart. Writing to the cache costs 2.5 times the input token price.

This is mainly a hardening release. Workspace settings are now read-only in untrusted folders. Several session-resume bugs are fixed, including duplicated tool turns, lost history and sessions that broke after pressing Ctrl-C quickly.

Telemetry config now supports custom OTLP headers, and OAuth callback checks now follow RFC 9207.