Covers autonomous runs, interactive ConPTY sessions (GetInteractiveLaunchSpec),
planning sessions, and improvement/planning children — every path that needs a
base commit now self-heals on a fresh 'git init' repo instead of surfacing
"ambiguous argument 'HEAD'" as a HubException.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
(cherry picked from commit ec16a85c495ceceaa22f922e077a27dcda54f035)