Co-located mode: the operator launches its own podman/docker container and
execs into it out-of-band (argv-identical to the native harness), exposed as
`sbx launch|status|down`, `exec`, `write`, `get`. When granted, it can also
drive the room's broker-owned container directly on the same host.
Relay mode primitive: `keys` injects raw bytes into the shared PTY via the
same `_sbx:input` frame a human driver emits — full keyboard control incl. the
stop-vocabulary (ctrl-c/ctrl-d/ctrl-z/ctrl-\, esc, arrows, pager q). A compact
per-session cheat-sheet (`sandbox.KEYS_HELP`, `keys --help-keys`) documents
what each inject does and how to end a stuck program, token-efficiently.
Gating: exec/write/get refuse a host (`local`) inherited from the room; the
room sandbox is only driven when `granted`. Keystrokes are inert until granted.
17 offline tests green; e2e verified against real podman (launch→exec→write→
get round-trip→teardown) and through the CLI socket.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>