diff --git a/routes/codex_routes.py b/routes/codex_routes.py
index 579f47ddb..e11965c35 100644
--- a/routes/codex_routes.py
+++ b/routes/codex_routes.py
@@ -790,7 +790,7 @@ def setup_codex_routes(
         norm = dict(body or {})
         sess = (norm.get("tmux_session") or norm.get("session_id") or "").strip()
         model = (norm.get("model") or norm.get("repo_id") or "").strip()
-        host = (norm.get("host") or norm.get("remote_host") or "").strip()
+        host = validate_remote_host((norm.get("host") or norm.get("remote_host") or "").strip() or None) or ""
         port = norm.get("port") or 8000
         import re as _re
         if not sess or not _re.fullmatch(r"[a-zA-Z0-9_-]+", sess):
diff --git a/tests/test_codex_ssh_host_validation.py b/tests/test_codex_ssh_host_validation.py
index 26da3963c..f376e71e5 100644
--- a/tests/test_codex_ssh_host_validation.py
+++ b/tests/test_codex_ssh_host_validation.py
@@ -7,12 +7,39 @@ in ``remoteHost`` would be injected into that command.
 These pin validation on the host/port before they reach the ssh string, matching
 the validators the rest of the cookbook routes already apply.
 """
+import asyncio
+
 import pytest
 from fastapi import HTTPException
+from starlette.requests import Request
 
 import routes.codex_routes as codex_routes
 
 
+def _route_endpoint(path: str, method: str):
+    router = codex_routes.setup_codex_routes()
+    for route in router.routes:
+        if route.path == path and method in route.methods:
+            return route.endpoint
+    raise AssertionError(f"{method} {path} route not found")
+
+
+def _launch_request() -> Request:
+    request = Request(
+        {
+            "type": "http",
+            "method": "POST",
+            "path": "/api/codex/cookbook/adopt",
+            "headers": [],
+            "state": {},
+        }
+    )
+    request.state.api_token = True
+    request.state.api_token_owner = "alice"
+    request.state.api_token_scopes = ["cookbook:launch"]
+    return request
+
+
 def test_rejects_remote_host_with_shell_metacharacters():
     task = {"remoteHost": "box; rm -rf ~", "sshPort": ""}
     with pytest.raises(HTTPException) as exc:
@@ -47,3 +74,26 @@ def test_default_ssh_port_omits_flag():
     )
     assert host == "box"
     assert port_flag == ""
+
+
+def test_adopt_rejects_ssh_option_host_before_shell(monkeypatch):
+    calls = []
+
+    async def fail_if_shell_runs(*args, **kwargs):
+        calls.append((args, kwargs))
+        raise RuntimeError("shell should not run for invalid host")
+
+    monkeypatch.setattr(asyncio, "create_subprocess_shell", fail_if_shell_runs)
+
+    endpoint = _route_endpoint("/api/codex/cookbook/adopt", "POST")
+    body = {
+        "tmux_session": "serve_abc123",
+        "model": "org/model",
+        "host": "-oProxyCommand=sh",
+    }
+
+    with pytest.raises(HTTPException) as exc:
+        asyncio.run(endpoint(_launch_request(), body))
+
+    assert exc.value.status_code == 400
+    assert calls == []