GPT-5.5 duplicates tool names in Codex App Remote SSH sessions

Summary

In a Codex App Remote SSH project connected to an Ubuntu Linux host, GPT-5.5 consistently emits duplicated tool names. The remote app-server rejects them as unsupported, so the agent cannot use the terminal or filesystem/resource tools. Switching the same remote project to GPT-5.4 makes tool use work immediately.

Environment

• Codex App for macOS: 26.623.141536 (build 4753)
• Remote Codex CLI/app-server: 0.143.0
• Remote OS: Ubuntu 24.04 LTS, Linux x86_64
• Connection: Codex App Remote SSH
• GPT-5.5 fails; GPT-5.4 works

Reproduction

1. Add a Linux host under Codex App Settings > Connections > SSH.
2. Add a remote project on that host.
3. Create a remote thread using GPT-5.5.
4. Ask it to run a simple read-only command such as hostname && whoami && pwd.
5. The tool invocation is rejected as unsupported.
6. Create a new thread for the same project using GPT-5.4 and repeat the command; it succeeds.

Remote app-server errors

unsupported call: exec_commandexec_command
unsupported call: list_mcp_resourceslist_mcp_resources
unsupported call: list_mcp_resource_templateslist_mcp_resource_templates

The duplication affects multiple tool names, suggesting a model/tool-routing or serialization issue rather than a shell, SSH, PATH, permission, or individual tool problem.

Checks performed

• Normal SSH authentication works.
• The remote project opens successfully.
• The visible terminal in the remote project runs commands correctly.
• The remote Codex daemon was restarted; the issue persisted.
• Client and remote app-server reported compatible/current versions.
• GPT-5.4 successfully executed the same commands in the same remote project.

Expected behavior

GPT-5.5 should emit the registered tool name once (for example, exec_command) and execute tools in Remote SSH threads as GPT-5.4 does.