T3 Code

T3 Code creates a worktree per thread and runs Claude Code in it.

Set up

boxer install claude-code
boxer install git
git add .claude .mcp.json && git commit -m "Run agent commands in boxer"

boxer install git is required. Without a warm sandbox, T3 Code's provider fails with turn/setPermissionMode failed while the sandbox boots (32 to 39 seconds cold).

Run the agent itself in the sandbox

boxer shim install --harness claude

Set the shim as the provider's binaryPath in T3 Code's settings. T3 Code starts the shim, the shim runs boxer shell claude, and Claude runs inside the sandbox.

Tested in the matrix.