The main group's project root was mounted read-write, allowing the
container agent to modify host application code (e.g. dist/container-runner.js)
to inject arbitrary mounts on next restart — a full sandbox escape.
Fix: mount the project root read-only. Writable paths the agent needs
(group folder, IPC, .claude/) are already mounted separately. The
agent-runner source is now copied into a per-group writable location
so agents can still customize container-side behavior without affecting
host code or other groups.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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