Fix Codex Remote thread writer conflicts

README.md

@@ -181,6 +181,7 @@ limit_re  = "usage limit|limit reached"
 [backend.codex]                 # Codex TUI, exposed through Codex Remote Control
 bin             = "codex"
 preamble        = "{bin} remote-control start --json >/dev/null"
+remote_addr     = "unix://"    # connect the TUI to that daemon (one shared thread writer)
 flags           = "--dangerously-bypass-approvals-and-sandbox --dangerously-bypass-hook-trust --no-alt-screen"
 supports_resume = false         # thread-ID persistence is not implemented by this harness
 prompt_delivery = "arg"
@@ -203,11 +204,14 @@ prompt_delivery = "exec"        # {kickoff}=prompt file, {session}=session name,
 
 For an `"arg"` backend the flag *templates* are configurable (so you can point at a non-claude
 CLI): `resume_flag` (default `--resume '{id}'`), `model_flag` (default `--model '{model}'`),
-`remote_control_flag` (default `--remote-control '{session}'`). A backend that sets `process_name`
+`remote_control_flag` (default `--remote-control '{session}'`), and `remote_addr_flag` (default
+`--remote '{addr}'`). A backend that sets `process_name`
 participates in backend-mismatch healing; one that doesn't (e.g. `demo`) never does.
 An optional `preamble` runs first and must succeed before the TUI starts; it supports `{bin}`,
 `{session}`, `{model}`, and `{dir}` templates. The Codex backend uses it to idempotently start the
-shared Remote Control daemon before launching each tmux-hosted Codex TUI.
+shared Remote Control daemon, then uses `remote_addr = "unix://"` to connect each tmux-hosted Codex
+TUI to that daemon. This keeps the app-server as the sole thread-store writer while local and
+Remote clients share the session.
 For an unattended TUI with a deterministic first-run gate, `startup_prompt_re` opts into one
 screen check after `startup_prompt_delay` seconds; on a match, the harness types the explicitly
 configured `startup_prompt_response` and `submit_key`. Codex uses this to trust the agent's