diff --git a/cmd_chat/operator/__main__.py b/cmd_chat/operator/__main__.py
index f5f4cfe..b4b35e9 100644
--- a/cmd_chat/operator/__main__.py
+++ b/cmd_chat/operator/__main__.py
@@ -58,6 +58,36 @@ def _build_parser() -> argparse.ArgumentParser:
     s.add_argument("text", nargs="+")
     s.add_argument("--session", default=None)
 
+    # ── sandbox drive ───────────────────────────────────────────────────
+    sb = sub.add_parser("sbx", help="manage the operator's own container")
+    sb.add_argument("action", choices=["launch", "status", "down"], nargs="?",
+                    default="status")
+    sb.add_argument("--engine", default=None, help="podman|docker (default: auto)")
+    sb.add_argument("--image", default=None, help="container image (default per engine)")
+    sb.add_argument("--name", default=None, help="container name (default: hh-op-<user>)")
+    sb.add_argument("--session", default=None)
+
+    ex = sub.add_parser("exec", help="run a shell command in the sandbox")
+    ex.add_argument("cmd", nargs="+")
+    ex.add_argument("--session", default=None)
+
+    wr = sub.add_parser("write", help="write a file in the sandbox (content from stdin or --text)")
+    wr.add_argument("path")
+    wr.add_argument("--text", default=None, help="inline content (else read stdin)")
+    wr.add_argument("--session", default=None)
+
+    gt = sub.add_parser("get", help="read a file out of the sandbox")
+    gt.add_argument("path")
+    gt.add_argument("--out", default=None, help="write to this local path (else stdout)")
+    gt.add_argument("--session", default=None)
+
+    ky = sub.add_parser("keys", help="inject keystrokes into the room's shared PTY")
+    ky.add_argument("keys", nargs="*",
+                    help="tokens: literal text, named keys (enter, ctrl-c, esc, "
+                         "up…), text:<verbatim>, hex:<bytes>")
+    ky.add_argument("--help-keys", action="store_true", help="print the key vocabulary")
+    ky.add_argument("--session", default=None)
+
     for v in ("roster", "status", "down"):
         sub.add_parser(v).add_argument("--session", default=None)
     return ap
@@ -191,6 +221,67 @@ def _run_say(args) -> int:
     return 0
 
 
+def _run_sbx(args) -> int:
+    resp = _client_request(args, {"op": "sbx", "action": args.action,
+                                  "engine": args.engine, "image": args.image,
+                                  "name": args.name})
+    print(json.dumps(resp))
+    return 0 if resp.get("ok") else 1
+
+
+def _run_exec(args) -> int:
+    cmd = " ".join(args.cmd)
+    resp = _client_request(args, {"op": "exec", "cmd": cmd})
+    out = resp.get("output", "")
+    if out:
+        sys.stdout.write(out if out.endswith("\n") else out + "\n")
+    if not resp.get("ok"):
+        if "error" in resp:
+            print(resp["error"], file=sys.stderr)
+        return resp.get("rc", 1) or 1
+    return 0
+
+
+def _run_write(args) -> int:
+    text = args.text if args.text is not None else sys.stdin.read()
+    resp = _client_request(args, {"op": "write", "path": args.path, "content": text})
+    if not resp.get("ok"):
+        print(resp.get("error", "write failed"), file=sys.stderr)
+        return 1
+    print(f"wrote {resp.get('path')} ({resp.get('bytes')} bytes)", file=sys.stderr)
+    return 0
+
+
+def _run_get(args) -> int:
+    import base64
+    resp = _client_request(args, {"op": "get", "path": args.path})
+    if not resp.get("ok"):
+        print(resp.get("error", "get failed"), file=sys.stderr)
+        return 1
+    raw = base64.b64decode(resp.get("b64", ""))
+    if args.out:
+        Path(args.out).write_bytes(raw)
+        print(f"wrote {args.out} ({len(raw)} bytes)", file=sys.stderr)
+    else:
+        sys.stdout.buffer.write(raw)
+    return 0
+
+
+def _run_keys(args) -> int:
+    from . import sandbox as sbx
+    if args.help_keys:
+        print(sbx.KEYS_HELP)
+        return 0
+    if not args.keys:
+        print("no keys given (try --help-keys)", file=sys.stderr)
+        return 2
+    resp = _client_request(args, {"op": "keys", "keys": args.keys})
+    if not resp.get("ok"):
+        print(resp.get("error", "keys failed"), file=sys.stderr)
+        return 1
+    return 0
+
+
 def _run_simple(args, op: str) -> int:
     resp = _client_request(args, {"op": op})
     print(json.dumps(resp))
@@ -208,6 +299,16 @@ def main(argv: list[str] | None = None) -> int:
         return _run_read(args)
     if verb == "say":
         return _run_say(args)
+    if verb == "sbx":
+        return _run_sbx(args)
+    if verb == "exec":
+        return _run_exec(args)
+    if verb == "write":
+        return _run_write(args)
+    if verb == "get":
+        return _run_get(args)
+    if verb == "keys":
+        return _run_keys(args)
     if verb in ("roster", "status", "down"):
         return _run_simple(args, verb)
     return 2
diff --git a/cmd_chat/operator/bridge.py b/cmd_chat/operator/bridge.py
index 05d10bc..224b0ad 100644
--- a/cmd_chat/operator/bridge.py
+++ b/cmd_chat/operator/bridge.py
@@ -25,6 +25,7 @@ import time
 import websockets
 
 from ..client.client import Client
+from . import sandbox as sbx
 from .session import Session
 
 
@@ -56,6 +57,12 @@ class OperatorBridge(Client):
         self.sbx_engine: str | None = None
         self.sbx_name: str = ""
 
+        # Co-located sandbox the operator launched itself (Phase 2). When set we
+        # exec straight into it (out-of-band); independent of the room's broker
+        # sandbox, which we can also drive when co-located + granted.
+        self._own_engine: str | None = None
+        self._own_name: str = ""
+
         # Live websocket (None while reconnecting); set in _connect_and_serve.
         self._ws = None
         self._stop = asyncio.Event()
@@ -285,6 +292,16 @@ class OperatorBridge(Client):
             return await self._op_read(req)
         if op == "say":
             return await self._op_say(req)
+        if op == "sbx":
+            return await self._op_sbx(req)
+        if op == "exec":
+            return await self._op_exec(req)
+        if op == "write":
+            return await self._op_write(req)
+        if op == "get":
+            return await self._op_get(req)
+        if op == "keys":
+            return await self._op_keys(req)
         if op == "down":
             asyncio.get_running_loop().call_soon(self._begin_shutdown)
             return {"ok": True, "stopping": True}
@@ -317,6 +334,141 @@ class OperatorBridge(Client):
         await self._emit("sent", **{"from": self.name}, text=text, addressed=False)
         return {"ok": True}
 
+    # ── sandbox drive (Phase 2) ──────────────────────────────────────────
+    def _target(self) -> tuple[str | None, str, str | None]:
+        """Pick the sandbox to exec into and report why.
+
+        Returns ``(engine, name, error)``. Prefer the operator's *own* container
+        (always ours to drive). Else, if the room granted us drive AND its broker
+        sandbox is a kind we can exec directly (we're co-located on this host),
+        target that. ``local`` is refused here — execing on the host is opt-in
+        only via our own `local` launch, never inherited from the room."""
+        if self._own_engine:
+            return self._own_engine, self._own_name, None
+        if self.granted and self.sbx_engine in ("docker", "podman", "multipass") \
+                and self.sbx_name:
+            return self.sbx_engine, self.sbx_name, None
+        if self.sbx_engine and not self.granted:
+            return None, "", "not a granted driver (owner must `/grant`)"
+        return None, "", "no sandbox — `sbx launch` one or join a room with one"
+
+    async def _op_sbx(self, req: dict) -> dict:
+        """Manage the operator's own co-located container: launch / status / down."""
+        action = req.get("action", "status")
+        if action == "launch":
+            engine = req.get("engine") or sbx.pick_engine()
+            if not engine:
+                return {"ok": False, "error": "no container engine (need podman or docker)"}
+            image = req.get("image") or sbx.default_image(engine)
+            name = req.get("name") or f"hh-op-{self.name}"
+            ok, msg = await sbx.launch_container(engine, name, image)
+            if ok:
+                self._own_engine, self._own_name = engine, name
+                await self._emit("sandbox", state="own-ready", engine=engine,
+                                 name=name, image=image)
+            return {"ok": ok, "engine": engine, "name": name, "image": image,
+                    "message": msg}
+        if action == "down":
+            if not self._own_engine:
+                return {"ok": False, "error": "no own sandbox to tear down"}
+            ok, msg = await sbx.teardown_container(self._own_engine, self._own_name)
+            if ok:
+                await self._emit("sandbox", state="own-down",
+                                 engine=self._own_engine, name=self._own_name)
+                self._own_engine, self._own_name = None, ""
+            return {"ok": ok, "message": msg}
+        # status
+        engine, name, err = self._target()
+        return {"ok": True, "target_engine": engine, "target_name": name,
+                "reason": err, "own_engine": self._own_engine,
+                "own_name": self._own_name, "room_engine": self.sbx_engine,
+                "room_name": self.sbx_name, "granted": self.granted}
+
+    async def _op_exec(self, req: dict) -> dict:
+        """Run a shell command in the target sandbox, capture combined output +
+        exit code. The command runs under `sh -c` (a real shell, intended) inside
+        the container — the container is the blast radius."""
+        cmd = str(req.get("cmd", ""))
+        if not cmd:
+            return {"ok": False, "error": "empty cmd"}
+        engine, name, err = self._target()
+        if err:
+            return {"ok": False, "error": err}
+        prefix = sbx.exec_prefix(engine, name)
+        if prefix is None:
+            return {"ok": False, "error": f"can't address {engine}/{name}"}
+        out, rc = await sbx.exec_capture(prefix + ["sh", "-c", cmd])
+        await self._emit("exec", engine=engine, name=name, cmd=cmd, rc=rc)
+        return {"ok": rc == 0, "rc": rc, "output": out, "engine": engine, "name": name}
+
+    async def _op_write(self, req: dict) -> dict:
+        """Write a file in the target sandbox. Content arrives on stdin (never
+        shell-parsed); the path is a positional arg. `mkdir -p` the parent first
+        so an absolute path into a new dir works. Mirrors the native harness."""
+        path = str(req.get("path", "")).strip()
+        if not path:
+            return {"ok": False, "error": "missing path"}
+        content = req.get("content", "")
+        data = content.encode() if isinstance(content, str) else bytes(content)
+        engine, name, err = self._target()
+        if err:
+            return {"ok": False, "error": err}
+        prefix = sbx.exec_prefix(engine, name)
+        if prefix is None:
+            return {"ok": False, "error": f"can't address {engine}/{name}"}
+        out, rc = await sbx.exec_capture(
+            prefix + ["sh", "-c", 'mkdir -p "$(dirname "$1")" && cat > "$1"',
+                      "hh-write", path],
+            stdin=data)
+        await self._emit("write", engine=engine, name=name, path=path, rc=rc)
+        return {"ok": rc == 0, "rc": rc, "path": path, "bytes": len(data),
+                "output": out if (out or "").strip() else ""}
+
+    async def _op_get(self, req: dict) -> dict:
+        """Read a file out of the target sandbox. Returns base64 (binary-safe);
+        the content is plumbing, so it's uncapped (unlike exec output)."""
+        path = str(req.get("path", "")).strip()
+        if not path:
+            return {"ok": False, "error": "missing path"}
+        engine, name, err = self._target()
+        if err:
+            return {"ok": False, "error": err}
+        prefix = sbx.exec_prefix(engine, name)
+        if prefix is None:
+            return {"ok": False, "error": f"can't address {engine}/{name}"}
+        raw, rc = await sbx.exec_capture(prefix + ["cat", "--", path], text=False)
+        if rc != 0:
+            return {"ok": False, "rc": rc,
+                    "error": f"read failed (exit={rc}): {raw.decode(errors='replace')[:200]}"}
+        return {"ok": True, "rc": 0, "path": path,
+                "b64": base64.b64encode(raw).decode(), "bytes": len(raw)}
+
+    async def _op_keys(self, req: dict) -> dict:
+        """Relay raw keystrokes into the room's *shared* PTY — the same
+        `_sbx:input` frame a human driver's terminal emits. The broker writes our
+        bytes to the shared shell iff we're a granted driver, so this is how the
+        operator drives a broker-owned sandbox (and tests interactive programs:
+        ctrl-c to stop, q to quit a pager, esc to leave vim). See
+        `sandbox.KEYS_HELP` for the byte vocabulary."""
+        if self._ws is None:
+            return {"ok": False, "error": "not connected to room"}
+        if not self.granted:
+            return {"ok": False, "error": "not a granted driver — keystrokes inert until `/grant`"}
+        spec = req.get("keys")
+        if spec in (None, "", []):
+            return {"ok": False, "error": "no keys", "help": sbx.KEYS_HELP}
+        try:
+            data = sbx.encode_keys(spec)
+        except ValueError as e:
+            return {"ok": False, "error": f"bad key spec: {e}"}
+        frame = json.dumps({"_sbx": "input", "b64": base64.b64encode(data).decode()})
+        try:
+            await self._ws.send(self.room_fernet.encrypt(frame.encode()).decode())
+        except Exception as e:  # noqa: BLE001
+            return {"ok": False, "error": f"send failed: {type(e).__name__}: {e}"}
+        await self._emit("keys", bytes=len(data))
+        return {"ok": True, "bytes": len(data)}
+
     def _begin_shutdown(self) -> None:
         self._stop.set()
         self.running = False
diff --git a/cmd_chat/operator/sandbox.py b/cmd_chat/operator/sandbox.py
new file mode 100644
index 0000000..517787b
--- /dev/null
+++ b/cmd_chat/operator/sandbox.py
@@ -0,0 +1,187 @@
+"""Sandbox primitives for the operator bridge — pure, dependency-light helpers.
+
+Two ways the operator touches a sandbox:
+
+1. **Co-located exec** (this module's `exec_*` / `launch_*`): the daemon owns a
+   container it started itself (`podman`/`docker run -d … sleep infinity`) and
+   runs commands *out-of-band* with `engine exec -i`. Output is captured and
+   returned — clean, scriptable, invisible to the room. Mirrors the native
+   harness's exec path (cmd_chat/agent/bridge.py:640-676) argv-for-argv so the
+   blast radius and quoting rules are identical.
+
+2. **Relay keystrokes** (`encode_keys`): when the *room's* shared sandbox is
+   owned by the Rust broker, the only way in is the same `_sbx:input` keystroke
+   frame a human driver's terminal emits. The broker writes our bytes to the
+   shared PTY iff we're a granted driver. That path needs a precise byte
+   vocabulary — including how to *stop* a running program — which lives here so
+   it's one tested table, reused by the bridge and documented once per session.
+
+Nothing here opens a websocket or holds state; the bridge wires these in.
+"""
+
+from __future__ import annotations
+
+import asyncio
+
+# Match the native harness so behaviour is identical across both drivers.
+EXEC_TIMEOUT = 60.0      # NATIVE_TOOL_TIMEOUT
+OUTPUT_CAP = 4096        # NATIVE_OUTPUT_CAP (bytes of combined stdout+stderr)
+
+
+# ── engine / image selection ───────────────────────────────────────────────
+def pick_engine() -> str | None:
+    """Prefer podman (rootless, daemonless, no sudo) then docker. None if neither
+    is on PATH — the caller surfaces that as a clear 'no engine' error."""
+    import shutil
+
+    for eng in ("podman", "docker"):
+        if shutil.which(eng):
+            return eng
+    return None
+
+
+def default_image(engine: str) -> str:
+    """Match the Rust/agent defaults: Podman→Kali, Docker→Parrot."""
+    return "kalilinux/kali-rolling" if engine == "podman" else "parrotsec/core"
+
+
+# ── co-located exec ─────────────────────────────────────────────────────────
+def exec_prefix(engine: str | None, name: str | None) -> list[str] | None:
+    """argv prefix that runs a program *inside* the named sandbox, or None if we
+    can't address it. The real program + args are appended as separate argv
+    elements (never a shell-interpolated string), so untrusted room text can't
+    inject shell metacharacters outside an explicit `sh -c`. `-i` keeps stdin
+    open so `write` can pipe file content in. Identical shape to the native
+    harness (bridge.py:640)."""
+    if engine in ("docker", "podman"):
+        return [engine, "exec", "-i", name] if name else None
+    if engine == "multipass":
+        return ["multipass", "exec", name, "--"] if name else None
+    if engine == "local":
+        return []  # host shell — explicit, opt-in exception
+    return None
+
+
+async def exec_capture(argv: list[str], stdin: bytes | None = None,
+                       text: bool = True) -> tuple[str | bytes, int]:
+    """Run an exec argv, capture combined stdout+stderr and the exit code,
+    time-bounded. `text=True` decodes + byte-caps for display; `text=False`
+    returns raw bytes uncapped (for `get`, where truncation would corrupt the
+    file). The container/VM is the blast radius; `local` is the host by choice."""
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            *argv,
+            stdin=asyncio.subprocess.PIPE if stdin is not None else asyncio.subprocess.DEVNULL,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.STDOUT,
+        )
+    except (FileNotFoundError, OSError) as e:
+        return (f"[exec failed: {e}]" if text else b""), 127
+    try:
+        out, _ = await asyncio.wait_for(proc.communicate(input=stdin), timeout=EXEC_TIMEOUT)
+    except asyncio.TimeoutError:
+        proc.kill()
+        return ("[command timed out]" if text else b""), 124
+    rc = proc.returncode if proc.returncode is not None else -1
+    if not text:
+        return out, rc
+    s = out.decode(errors="replace")
+    if len(s) > OUTPUT_CAP:
+        s = s[:OUTPUT_CAP] + "\n[output truncated]"
+    return s, rc
+
+
+async def launch_container(engine: str, name: str, image: str) -> tuple[bool, str]:
+    """Start a persistent throwaway container we can exec into: remove any stale
+    one, then `run -d --name … --hostname … -w /root <image> sleep infinity`
+    (argv-identical to hh/src/sbx.rs:779). Returns (ok, message)."""
+    await exec_capture([engine, "rm", "-f", name])  # ignore "no such container"
+    out, rc = await exec_capture(
+        [engine, "run", "-d", "--name", name, "--hostname", name,
+         "-w", "/root", image, "sleep", "infinity"])
+    if rc != 0:
+        tail = (out or "").strip().splitlines()[-1:] or [""]
+        return False, f"{engine} run failed (exit={rc}): {tail[0]}"
+    return True, f"launched {engine} container '{name}' from {image}"
+
+
+async def teardown_container(engine: str, name: str) -> tuple[bool, str]:
+    out, rc = await exec_capture([engine, "rm", "-f", name])
+    if rc != 0:
+        return False, f"{engine} rm failed (exit={rc}): {(out or '').strip()[:200]}"
+    return True, f"removed {engine} container '{name}'"
+
+
+# ── relay keystrokes (shared-PTY drive) ─────────────────────────────────────
+#
+# A terminal is just a byte stream. Named keys below are the bytes a real
+# keyboard sends; the bridge base64-wraps them into a `{"_sbx":"input"}` frame.
+# The control characters are the *how to stop things* vocabulary — being able to
+# interrupt a hung program is as essential as starting one, especially in tests.
+NAMED_KEYS: dict[str, bytes] = {
+    # line endings / whitespace
+    "enter": b"\r", "return": b"\r", "newline": b"\n", "tab": b"\t",
+    "space": b" ", "backspace": b"\x7f",
+    # the stop/exit family — the most important keys for staying unstuck
+    "ctrl-c": b"\x03",   # SIGINT  — interrupt the foreground program
+    "ctrl-d": b"\x04",   # EOF     — end stdin / exit an empty shell
+    "ctrl-z": b"\x1a",   # SIGTSTP — suspend to the background (then `fg`/`bg`)
+    "ctrl-\\": b"\x1c",  # SIGQUIT — hard quit + core dump when SIGINT is ignored
+    "esc": b"\x1b",      # leave vim insert-mode, dismiss menus, abort readline
+    # screen / job control niceties
+    "ctrl-l": b"\x0c",   # clear/redraw the screen
+    "ctrl-u": b"\x15",   # kill the input line (clear a half-typed command)
+    "ctrl-a": b"\x01",   # start-of-line (also tmux/screen prefix)
+    "ctrl-e": b"\x05",   # end-of-line
+    "ctrl-k": b"\x0b",   # kill to end-of-line
+    "ctrl-w": b"\x17",   # delete the previous word
+    # arrows / paging — ANSI sequences (history, menus, pagers)
+    "up": b"\x1b[A", "down": b"\x1b[B", "right": b"\x1b[C", "left": b"\x1b[D",
+    "home": b"\x1b[H", "end": b"\x1b[F",
+    "pageup": b"\x1b[5~", "pagedown": b"\x1b[6~",
+    "delete": b"\x1b[3~",
+}
+
+# Token-efficient cheat-sheet the skill/status surfaces once per session, so a
+# Claude operator knows the stop-vocabulary without re-deriving it every turn.
+KEYS_HELP = (
+    "send-keys vocabulary (bytes → shared PTY; granted drivers only):\n"
+    "  literal text          types it verbatim (no trailing newline)\n"
+    "  enter/tab/space/esc    \\r \\t ' ' \\x1b\n"
+    "  ctrl-c   interrupt the running program (SIGINT) — your main 'stop'\n"
+    "  ctrl-d   EOF: end stdin / exit an empty shell\n"
+    "  ctrl-z   suspend to background (resume with `fg`); ctrl-\\ = SIGQUIT\n"
+    "  ctrl-u   clear a half-typed line; ctrl-l clears the screen\n"
+    "  up/down/left/right home end pageup pagedown delete backspace\n"
+    "  q        quits most pagers (less/man); :q<enter> quits vim\n"
+    "End a stuck command with ctrl-c; if that's ignored, ctrl-\\ then ctrl-c again."
+)
+
+
+def encode_keys(spec) -> bytes:
+    """Resolve a key spec into the raw bytes to inject.
+
+    Accepts either a list of tokens or a single string:
+      - a NAMED_KEYS name (case-insensitive)  → that control sequence
+      - 'text:...'                             → the rest, verbatim (preserves a
+                                                  literal name like 'enter')
+      - 'hex:1b5b41' / '\\x1b'                  → raw bytes from hex
+      - anything else                          → typed verbatim as UTF-8
+
+    A bare string with no recognised token is typed as-is, so the common case
+    (`send-keys "ls -la" enter`) is one obvious call. Naming is explicit on
+    purpose: nothing here guesses, so an operator always knows what it sent."""
+    tokens = spec if isinstance(spec, (list, tuple)) else [spec]
+    out = bytearray()
+    for tok in tokens:
+        s = "" if tok is None else str(tok)
+        low = s.lower()
+        if low in NAMED_KEYS:
+            out += NAMED_KEYS[low]
+        elif s.startswith("text:"):
+            out += s[5:].encode()
+        elif low.startswith("hex:"):
+            out += bytes.fromhex(s[4:])
+        else:
+            out += s.encode()
+    return bytes(out)
diff --git a/tests/test_operator_bridge.py b/tests/test_operator_bridge.py
index d69ed7e..131ae8c 100644
--- a/tests/test_operator_bridge.py
+++ b/tests/test_operator_bridge.py
@@ -14,6 +14,7 @@ sys.path.insert(0, str(Path(__file__).parent.parent))
 from cryptography.fernet import Fernet
 
 from cmd_chat.operator.bridge import OperatorBridge
+from cmd_chat.operator import sandbox as sbx
 
 
 def _bridge(name="oracle", trigger=None):
@@ -195,3 +196,79 @@ def test_dispatch_status_and_roster():
         unknown = await b._dispatch({"op": "frobnicate"})
         assert unknown["ok"] is False
     asyncio.run(go())
+
+
+# ── sandbox: keystroke encoding (the stop-vocabulary) ─────────────────────
+def test_encode_keys_named_and_literal():
+    assert sbx.encode_keys(["ls -la", "enter"]) == b"ls -la\r"
+    assert sbx.encode_keys("ctrl-c") == b"\x03"          # SIGINT
+    assert sbx.encode_keys("ctrl-d") == b"\x04"          # EOF
+    assert sbx.encode_keys(["CTRL-C"]) == b"\x03"        # case-insensitive
+    assert sbx.encode_keys("up") == b"\x1b[A"            # ANSI arrow
+    # 'text:' forces verbatim so a literal word like "enter" can be typed
+    assert sbx.encode_keys(["text:enter"]) == b"enter"
+    assert sbx.encode_keys("hex:1b5b41") == b"\x1b[A"
+    # a bare unknown string is typed as-is
+    assert sbx.encode_keys("q") == b"q"
+
+
+def test_exec_prefix_shapes():
+    assert sbx.exec_prefix("podman", "box") == ["podman", "exec", "-i", "box"]
+    assert sbx.exec_prefix("docker", "box") == ["docker", "exec", "-i", "box"]
+    assert sbx.exec_prefix("multipass", "vm") == ["multipass", "exec", "vm", "--"]
+    assert sbx.exec_prefix("local", "x") == []
+    assert sbx.exec_prefix("podman", "") is None        # unaddressable
+    assert sbx.exec_prefix("qemu", "x") is None
+
+
+# ── sandbox: target gating ────────────────────────────────────────────────
+def test_target_prefers_own_then_granted_room():
+    async def go():
+        b = _bridge("oracle")
+        # nothing yet → a clear error, no target
+        eng, name, err = b._target()
+        assert eng is None and err and "no sandbox" in err
+        # room has a sandbox but we're not granted → refused
+        b.sbx_engine, b.sbx_name = "podman", "hack-house"
+        eng, name, err = b._target()
+        assert eng is None and "granted" in err
+        # granted → drive the room's container directly (co-located exec)
+        b.granted = True
+        eng, name, err = b._target()
+        assert (eng, name, err) == ("podman", "hack-house", None)
+        # our own container always wins
+        b._own_engine, b._own_name = "podman", "hh-op-oracle"
+        eng, name, err = b._target()
+        assert (eng, name, err) == ("podman", "hh-op-oracle", None)
+    asyncio.run(go())
+
+
+def test_keys_requires_connection_and_grant():
+    async def go():
+        b = _bridge("oracle")
+        # not connected
+        r = await b._op_keys({"keys": ["enter"]})
+        assert r["ok"] is False and "not connected" in r["error"]
+        # connected but not granted → inert
+        b._ws = FakeWS()
+        r = await b._op_keys({"keys": ["enter"]})
+        assert r["ok"] is False and "granted" in r["error"]
+        # granted → injects an encrypted _sbx:input frame
+        b.granted = True
+        r = await b._op_keys({"keys": ["ls", "enter"]})
+        assert r["ok"] is True and r["bytes"] == 3
+        frame = json.loads(b.room_fernet.decrypt(b._ws.sent[0].encode()).decode())
+        assert frame["_sbx"] == "input"
+        import base64 as _b64
+        assert _b64.b64decode(frame["b64"]) == b"ls\r"
+    asyncio.run(go())
+
+
+def test_exec_requires_target():
+    async def go():
+        b = _bridge("oracle")
+        r = await b._op_exec({"cmd": "echo hi"})
+        assert r["ok"] is False and "no sandbox" in r["error"]
+        r = await b._op_exec({"cmd": ""})
+        assert r["ok"] is False and "empty" in r["error"]
+    asyncio.run(go())