Function create_worktree 

pub fn create_worktree(
    spec_id: &str,
    branch: &str,
    project_name: Option<&str>,
) -> Result<PathBuf>

Creates a new git worktree for the given spec.

This function is serialized to prevent concurrent git worktree add calls from racing on git’s internal locks. If worktree creation fails due to a lock error, it will retry once after a short delay.

Arguments

• spec_id - The specification ID (used to create unique worktree paths)
• branch - The branch name to create in the worktree
• project_name - Optional project name to namespace the worktree path

Returns

The absolute path to the created worktree directory.

Errors

Returns an error if:

• Git worktree creation fails after retry
• Directory cleanup/creation fails