Agents can now run commands and build files in the shared sandbox, but
only when explicitly invoked with the `!` verb and only while the owner
has granted drive. Reuses the existing driver ACL + `_sbx:input` frames:
the Python agent emits the same input frames a human driver does, gated
by the broker's `app.drivers` check — no new transport.
Guardrails: a regex gate holds destructive commands until `/ai <name>
confirm`; blast-radius caps (20 cmds / 8KB); the agent echoes its plan to
the room before running (audit trail). Owner controls: `/grant`, `/ai
start <model> allow` to pre-grant on spawn, and a Ctrl-X panic kill
switch (revoke all non-owner drive + Ctrl-C the shell). The broker now
re-broadcasts the ACL on join so a freshly-summoned agent actually
receives its grant.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>