Background subagents lost on session exit: check tree, then resume

If the Claude Code process exits while background subagents are running, they stop and their uncommitted work may be gone. Before resuming, run git status and git diff in each repo the agents touched to see what actually landed; don't trust what the agents' last messages imply. Resume each agent by messaging its id. Tell it explicitly which of its edits are missing and which shared resources (e.g. a Docker image) don't exist yet, so it doesn't assume earlier progress. Also check related repos: edits you made yourself may already be committed locally, so an empty diff can look like lost work.