Main-guard doesn't recognize worktree session - blocks all edits

[Jaggerxtrm]

Problem

When a user claims an issue and a worktree is created, the main-guard extension still blocks all file edits because it checks the branch at ctx.cwd (which is main) instead of recognizing the worktree session.

Current Behavior

1. User runs bd update <id> --claim
2. Session-flow creates worktree at .worktrees/<id>
3. User tries to edit a file
4. Main-guard sees main branch and blocks: "start on a feature branch"
5. User has NO way to work in the worktree (Pi doesn't support cd to worktree)

Expected Behavior

Main-guard should:

1. Check for .xtrm-session-state.json at cwd
2. If worktreePath exists, allow edits (or redirect to worktree)
3. Or session-flow should change ctx.cwd to worktree path

Workaround

None currently - users are blocked entirely

Related

• Discovered in: jaggers-agent-tools-hehp (Pi parity test)
• Affects: Pi runtime (Claude users can manually cd to worktree)