Add bounded stdin to owner execution

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a06def-6490-7033-8448-2eab2d12ed44

scripts/smoke-bwrap-owner-api.py

@@ -49,13 +49,14 @@ def main() -> int:
             created.raise_for_status()
             sandbox_id = created.json()["sandbox_id"]
             code = (
-                "import json, os; from pathlib import Path; "
+                "import json, os, sys; from pathlib import Path; task=sys.stdin.read(); "
                 f"outside=Path({str(outside)!r}).exists(); "
                 "interfaces=[line.split(':',1)[0].strip() for line in "
                 "Path('/proc/net/dev').read_text().splitlines()[2:]]; "
                 "print(json.dumps({'cwd':str(Path.cwd()), 'copied':Path('copied.txt').is_file(), "
                 "'host_source_visible':outside, 'network_interfaces':interfaces, "
-                "'run_id':os.environ.get('SANDBOXER_RUN_ID')}))"
+                "'run_id':os.environ.get('SANDBOXER_RUN_ID'), "
+                "'stdin_bytes':len(task.encode())}))"
             )
             executed = client.post(
                 f"/v1/sandboxes/{sandbox_id}/exec",
@@ -63,6 +64,7 @@ def main() -> int:
                 json={
                     "command": ["/usr/bin/python3", "-c", code],
                     "consumer": consumer,
+                    "stdin_text": '{"title":"non-secret API smoke"}',
                     "timeout_seconds": 30,
                     "max_output_bytes": 65_536,
                 },
@@ -95,6 +97,8 @@ def main() -> int:
                 and proof["copied"]
                 and not proof["host_source_visible"]
                 and proof["network_interfaces"] == ["lo"]
+                and proof["stdin_bytes"] == 32
+                and "stdin_text" not in result
                 and payload["teardown"]["workspace_removed"]
             )
             return 0 if passed else 1