Release, mostly facts

Claude Code v2.1.309

Fixes sandbox escape issues
Closes gaps in Bash permission checks
Fixes worktree isolation bypasses
Adds write protection for MCP config

What the research found

Claude Code v2.1.309 is a bugfix release fixing sandbox escapes, Bash permission check gaps, worktree isolation bypasses and MCP config write protection.

Claims and how well the evidence supports them

Fixed sandboxed Bash commands on macOS and Linux running shell startup files outside the sandbox 94%
Fixed worktree-isolated sessions accepting locale-prefixed commands the isolation guard should refuse 99%
Fixed sandboxed commands and auto-accepted edits modifying the MCP config file passed with --mcp-config 86%

Evidence

github.com https://github.com/anthropics/claude-code/releases/tag/v2.1.309

Actionability rated high.