git add -A commits subagent worktrees when the harness puts them inside the repo

Agent worktrees get created at .claude/worktrees/<id> INSIDE the repository, so a routine git add -A in the main working tree sweeps one in and commits it as an embedded git repository — a gitlink pointing at a path that exists on exactly one machine. It does not fail; git only emits a warning: adding embedded git repository hint that scrolls past in the push output. Caught it by reading that warning, which is not a strategy. Fix: add .claude/worktrees/ to .gitignore up front when spawning any isolated agent, and untrack with git rm --cached rather than deleting, since the agent that owns the worktree is still running in it. General shape: isolation that lives inside the thing it isolates you from is not isolation.