Code-mode tool host IPC decode failure: unknown field code_mode_host_duration_ns

What version of Codex CLI is running?

codex-cli 0.152.0

What subscription do you have?

PRO

Which model were you using?

gpt-5.6-terra

What platform is your computer?

Linux 6.14.0-37-generic x86_64 unknown

What terminal emulator and version are you using (if applicable)?

bash

Codex doctor report

{
      "schemaVersion": 1,
      "generatedAt": "1788285968s since unix epoch",
      "overallStatus": "ok",
      "codexVersion": "0.152.0",
      "checks": {
        "app_server.status": {
          "id": "app_server.status",
          "category": "app-server",
          "status": "ok",
          "summary": "background server is running",
          "details": {
            "app-server version": "0.151.0",
            "control socket": "/root/.codex/app-server-control/app-server-control.sock",
            "daemon state dir": "/root/.codex/app-server-daemon",
            "mode": "ephemeral",
            "pid file": "/root/.codex/app-server-daemon/app-server.pid (missing)",
            "settings": "/root/.codex/app-server-daemon/settings.json (missing)",
            "status": "running",
            "update-loop pid file": "/root/.codex/app-server-daemon/app-server-updater.pid (missing)"
          },
          "remediation": null,
          "durationMs": 57
        },
    … +309 lines (ctrl + t to view transcript)
            "terminal title source": "default"
          },
          "remediation": null,
          "durationMs": 0
        },
        "updates.status": {
          "id": "updates.status",
          "category": "updates",
          "status": "ok",
          "summary": "update configuration is locally consistent",
          "details": {
            "cached latest version": "0.152.0",
            "check for update on startup": "true",
            "last checked at": "2026-09-01T16:16:56.938838556Z",
            "latest version": "0.152.0",
            "latest version status": "current version is not older",
            "npm update target": "/usr/local/lib/node_modules/@openai/codex",
            "update action": "npm install -g @openai/codex",
            "version cache": "/root/.codex/version.json"
          },
          "remediation": null,
          "durationMs": 445
        }
      }
    }

What issue are you seeing?

Summary

All tool calls fail before the requested operation is executed. The failure appears to be caused by an IPC/protocol mismatch between the code-mode tool host and the client
decoding its response.

Error

failed to read code-mode host message:
failed to decode code-mode IPC frame:
unknown field `code_mode_host_duration_ns`,
expected one of `cell_id`, `content_items`, `error_text`

### Steps to reproduce

1. Start a Codex session with code-mode tools enabled.
2. Run a minimal command through the tool host, for example:

   pwd

   or:

   true

3. Observe that the operation fails before command output is returned.

The same error also occurs when attempting:

- local shell reads,
- Google Drive-related work,
- web search.

### Expected behavior

The tool response should decode successfully and return the command or tool result.

### Actual behavior

Every attempt fails while decoding the IPC frame. No target command or downstream service call appears to run.

### Impact

The session cannot use any tool-backed capability, including filesystem work, web/GitHub search, Google Drive access, and TTS workflows.

### Notes

- This does not appear to be an OpenAI TTS/API error: no TTS request is reached.
- The error suggests that the host emits a newer code_mode_host_duration_ns field while the client-side decoder only accepts cell_id, content_items, and error_text.
- Restarting/retrying within the same session did not resolve the issue.

### What steps can reproduce the bug?

### Environment

- Codex CLI: `0.152.0`
- App server reported by `codex doctor --json`: `0.151.0`
- Model: `gpt-5.6-terra`
- OS: Debian 12, Linux `6.14.0-37-generic`, `x86_64`
- Auth mode: ChatGPT
- Installation: npm
- Terminal transport: SSH, `TERM=xterm-256color`

### Reproduction steps


   ```text
4. Instead of returning the command output, the tool call fails with:

   failed to read code-mode host message:
   failed to decode code-mode IPC frame:
   unknown field `code_mode_host_duration_ns`,
   expected one of `cell_id`, `content_items`, `error_text`

5. Repeat with an operation that should have no output or dependencies:

   Run `true`.

   The same IPC-decoding error occurs.

6. The failure also occurs when Codex attempts other tool-backed actions, including local file reads and web search.

### Control observation

The commands themselves work when run directly in the terminal. For example, codex --version, uname -mprs, and codex doctor --json complete successfully. codex doctor --json
reports overall status ok and provider/WebSocket reachability as successful.

Thread ID: not available.

### What is the expected behavior?

Codex should execute the requested tool-backed command and return its result.

For the reproduction command:

```sh
pwd

the expected result is the current workspace directory, for example:

/root/mm/project

More generally, the code-mode tool host response should be decoded successfully. It should not fail because of an unrecognized IPC field. Minimal commands such as pwd and true
should work, and other tool-backed features should remain available.

### Additional information

_No response_

Start at the code-mode IPC frame decoder and the code-mode tool host response schema. Reproduce the mismatch with minimal commands such as pwd or true, then verify that the response decodes and returns command output without rejecting code_mode_host_duration_ns.