Fix Codex Remote thread writer conflicts

tests/smoke_codex.sh

@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
 # Isolated live smoke of the Codex backend, driven entirely through agents.py.
-# It starts one uniquely-named tmux session, verifies Remote Control and the Codex TUI, then
-# removes only that session. The shared Remote Control daemon intentionally remains available.
+# It starts one uniquely-named tmux session, verifies Remote Control and a daemon-connected Codex
+# TUI, then removes only that session. The shared Remote Control daemon intentionally remains
+# available.
 set -uo pipefail
 
 HERE="$(cd "$(dirname "$0")" && pwd)"
@@ -54,6 +55,7 @@ watch          = "none"
 [backend.codex]
 bin             = "$CODEX_BIN"
 preamble        = "{bin} remote-control start --json >/dev/null"
+remote_addr     = "unix://"
 flags           = "--dangerously-bypass-approvals-and-sandbox --dangerously-bypass-hook-trust --no-alt-screen"
 supports_resume = false
 prompt_delivery = "arg"