Codex ignores model_reasoning_effort on new session startup

[agustinrromero]

What version of Codex CLI is running?

codex-cli 0.139.0

What subscription do you have?

Enterprise

Which model were you using?

No response

What platform is your computer?

Linux 7.0.12-100.fc43.x86_64 x86_64 unknown

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

Alacritty + Tmux

Codex doctor report

{
  "schemaVersion": 1,
  "generatedAt": "1781379382s since unix epoch",
  "overallStatus": "warning",
  "codexVersion": "0.139.0",
  "checks": {
    "app_server.status": {
      "id": "app_server.status",
      "category": "app-server",
      "status": "ok",
      "summary": "background server is not running",
      "details": {
        "control socket": "/home/agustinrromero/.codex/app-server-control/app-server-control.sock",
        "daemon state dir": "/home/agustinrromero/.codex/app-server-daemon",
        "mode": "ephemeral",
        "pid file": "/home/agustinrromero/.codex/app-server-daemon/app-server.pid (missing)",
        "settings": "/home/agustinrromero/.codex/app-server-daemon/settings.json (missing)",
        "status": "not running",
        "update-loop pid file": "/home/agustinrromero/.codex/app-server-daemon/app-server-updater.pid (missing)"
      },
      "remediation": null,
      "durationMs": 0
    },
    "auth.credentials": {
      "id": "auth.credentials",
      "category": "auth",
      "status": "ok",
      "summary": "auth is configured",
      "details": {
        "auth env vars present": "OPENAI_API_KEY",
        "auth file": "/home/agustinrromero/.codex/auth.json",
        "auth storage mode": "File",
        "stored API key": "false",
        "stored ChatGPT tokens": "true",
        "stored agent identity": "false",
        "stored auth mode": "chatgpt"
      },
      "remediation": null,
      "durationMs": 0
    },
    "config.load": {
      "id": "config.load",
      "category": "config",
      "status": "ok",
      "summary": "config loaded",
      "details": {
        "CODEX_HOME": "/home/agustinrromero/.codex",
        "config.toml": "/home/agustinrromero/.codex/config.toml",
        "config.toml parse": "ok",
        "cwd": "/home/agustinrromero/.codex",
        "enabled feature flags": "shell_tool, unified_exec, shell_snapshot, terminal_resize_reflow, sqlite, apply_patch_streaming_events, hooks, enable_request_compression, multi_agent, multi_agent_v2, apps, tool_suggest, plugins, in_app_browser, browser_use, browser_use_external, computer_use, plugin_sharing, image_generation, skill_mcp_dependency_install, steer, guardian_approval, goals, collaboration_modes, tool_call_mcp_elicitation, personality, fast_mode, tui_app_server, prevent_idle_sleep, workspace_dependencies",
        "feature flag overrides": "apply_patch_streaming_events=true, multi_agent_v2=true, prevent_idle_sleep=true",
        "feature flags enabled": "30",
        "log dir": "/home/agustinrromero/.codex/log",
        "mcp servers": "2",
        "model": "gpt-5.5",
        "model provider": "openai",
        "sqlite home": "/home/agustinrromero/.codex"
      },
      "remediation": null,
      "durationMs": 0
    },
    "git.environment": {
      "id": "git.environment",
      "category": "git",
      "status": "ok",
      "summary": "git version 2.54.0",
      "details": {
        "PATH git #1": "/usr/bin/git",
        "PATH git entries": "1",
        "git build options": "git version 2.54.0; cpu: x86_64; no commit associated with this build; sizeof-long: 8; sizeof-size_t: 8; shell-path: /bin/sh; rust: disabled; gettext: enabled; libcurl: 8.15.0; OpenSSL: OpenSSL 3.5.4 30 Sep 2025; zlib-ng: 2.3.3; SHA-1: SHA1_DC; SHA-256: SHA256_BLK; default-ref-format: files; default-hash: sha1",
        "git exec path": "/usr/libexec/git-core",
        "git version": "git version 2.54.0",
        "repo detected": "false",
        "selected git": "/usr/bin/git"
      },
      "remediation": null,
      "durationMs": 51
    },
    "installation": {
      "id": "installation",
      "category": "install",
      "status": "ok",
      "summary": "installation looks consistent",
      "details": {
        "PATH codex #1": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/bin/codex",
        "current executable": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/bin/codex",
        "install context": "npm (package /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl, bin /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/bin, resources /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/codex-resources, path /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/codex-path)",
        "managed by bun": "false",
        "managed by npm": "true",
        "managed package root": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex",
        "npm update target": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex"
      },
      "remediation": null,
      "durationMs": 146
    },
    "mcp.config": {
      "id": "mcp.config",
      "category": "mcp",
      "status": "warning",
      "summary": "MCP configuration has optional issues",
      "details": {
        "configured servers": "2",
        "disabled servers": "0",
        "playwright": "env var REMOTE_ENV is not set",
        "stdio servers": "2"
      },
      "remediation": "Set the missing MCP env vars or disable the affected server.",
      "durationMs": 0
    },
    "network.env": {
      "id": "network.env",
      "category": "network",
      "status": "ok",
      "summary": "network-related environment looks readable",
      "details": {
        "proxy env vars": "none"
      },
      "remediation": null,
      "durationMs": 0
    },
    "network.provider_reachability": {
      "id": "network.provider_reachability",
      "category": "reachability",
      "status": "ok",
      "summary": "active provider endpoints are reachable over HTTP",
      "details": {
        "openai API base URL": "https://api.openai.com/v1 reachable (HTTP 404)",
        "openai API route probe": "https://api.openai.com/v1/<redacted> route exists (HTTP 401)",
        "reachability mode": "API key auth"
      },
      "remediation": null,
      "durationMs": 590
    },
    "network.websocket_reachability": {
      "id": "network.websocket_reachability",
      "category": "websocket",
      "status": "ok",
      "summary": "Responses WebSocket handshake succeeded",
      "details": {
        "DNS": "2 IPv4, 2 IPv6, first IPv6",
        "auth mode": "chatgpt",
        "connect timeout": "15000 ms",
        "endpoint": "wss://chatgpt.com/backend-api/<redacted>",
        "handshake result": "HTTP 101 Switching Protocols",
        "model provider": "openai",
        "models etag present": "true",
        "provider name": "OpenAI",
        "proxy env vars": "none",
        "reasoning header": "false",
        "server model present": "false",
        "supports websockets": "true",
        "wire API": "responses"
      },
      "remediation": null,
      "durationMs": 682
    },
    "runtime.provenance": {
      "id": "runtime.provenance",
      "category": "runtime",
      "status": "ok",
      "summary": "running npm on linux-x86_64",
      "details": {
        "commit": "unknown",
        "current executable": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/bin/codex",
        "install method": "npm (package /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl, bin /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/bin, resources /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/codex-resources, path /home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/codex-path)",
        "platform": "linux-x86_64",
        "version": "0.139.0"
      },
      "remediation": null,
      "durationMs": 0
    },
    "runtime.search": {
      "id": "runtime.search",
      "category": "search",
      "status": "ok",
      "summary": "search is OK (bundled)",
      "details": {
        "search command": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex/node_modules/@openai/codex-linux-x64/vendor/x86_64-unknown-linux-musl/codex-path/rg",
        "search command readiness": "file exists",
        "search provider": "bundled"
      },
      "remediation": null,
      "durationMs": 0
    },
    "sandbox.helpers": {
      "id": "sandbox.helpers",
      "category": "sandbox",
      "status": "ok",
      "summary": "sandbox configuration is readable",
      "details": {
        "approval policy": "OnRequest",
        "codex-linux-sandbox helper": "/home/agustinrromero/.codex/tmp/arg0/codex-arg0ebJBfs/codex-linux-sandbox",
        "execve wrapper helper": "/home/agustinrromero/.codex/tmp/arg0/codex-arg0ebJBfs/codex-execve-wrapper",
        "filesystem sandbox": "restricted",
        "network sandbox": "enabled"
      },
      "remediation": null,
      "durationMs": 0
    },
    "state.paths": {
      "id": "state.paths",
      "category": "state",
      "status": "ok",
      "summary": "state paths and databases are inspectable",
      "details": {
        "CODEX_HOME": "/home/agustinrromero/.codex (dir)",
        "active rollout files": "778 files, 344401143 total bytes, 442674 average bytes",
        "archived rollout files": "0 files, 0 total bytes, 0 average bytes",
        "goals DB": "/home/agustinrromero/.codex/goals_1.sqlite (file)",
        "goals DB integrity": "ok",
        "log DB": "/home/agustinrromero/.codex/logs_2.sqlite (file)",
        "log DB integrity": "ok",
        "log dir": "/home/agustinrromero/.codex/log (missing)",
        "memories DB": "/home/agustinrromero/.codex/memories_1.sqlite (file)",
        "memories DB integrity": "ok",
        "sqlite home": "/home/agustinrromero/.codex (dir)",
        "state DB": "/home/agustinrromero/.codex/state_5.sqlite (file)",
        "state DB integrity": "ok"
      },
      "remediation": null,
      "durationMs": 1224
    },
    "state.rollout_db_parity": {
      "id": "state.rollout_db_parity",
      "category": "threads",
      "status": "warning",
      "summary": "rollout files and state DB thread inventory differ",
      "details": {
        "default model provider": "openai",
        "rollout DB active files": "778",
        "rollout DB active rows": "778",
        "rollout DB archive mismatches": "0",
        "rollout DB archived files": "0",
        "rollout DB archived rows": "31",
        "rollout DB duplicate DB paths": "0",
        "rollout DB duplicate rollout thread ids": "0",
        "rollout DB malformed file names": "0",
        "rollout DB missing active rows": "0",
        "rollout DB missing archived rows": "0",
        "rollout DB model providers": "openai=809",
        "rollout DB rows": "809",
        "rollout DB scan cap reached": "false",
        "rollout DB scan errors": "0",
        "rollout DB sources": "cli=467, unknown=275, subagent:thread_spawn=46, subagent:review=10, vscode=9, exec=2",
        "rollout DB stale row sample": [
          "/home/agustinrromero/.codex/archived_sessions/rollout-2026-03-12T23-57-14-019ce520-7051-78f2-b1d0-673b6835d6c5.jsonl",
          "/home/agustinrromero/.codex/archived_sessions/rollout-2026-03-12T23-59-29-019ce522-7e67-77e2-9e7e-0bcd74b5eca7.jsonl",
          "/home/agustinrromero/.codex/archived_sessions/rollout-2026-03-13T00-00-56-019ce523-d275-78b1-9973-0fd05a064fea.jsonl",
          "/home/agustinrromero/.codex/archived_sessions/rollout-2026-03-13T00-02-28-019ce525-3a77-7b23-adab-65c8661ee3b8.jsonl",
          "/home/agustinrromero/.codex/archived_sessions/rollout-2026-03-13T00-10-22-019ce52c-783f-7a03-8b7f-2649ff6fb8a3.jsonl"
        ],
        "rollout DB stale rows": "31"
      },
      "issues": [
        {
          "severity": "warning",
          "cause": "state DB rows point at missing or unusable rollout files",
          "measured": "31 stale rows",
          "expected": "every state DB rollout path is a file on disk",
          "remedy": null,
          "fields": []
        }
      ],
      "remediation": null,
      "durationMs": 6702
    },
    "system.environment": {
      "id": "system.environment",
      "category": "system",
      "status": "ok",
      "summary": "OS language en-US",
      "details": {
        "EDITOR": "set",
        "LANG": "en_US.UTF-8",
        "LESS": "set",
        "PAGER": "set",
        "VISUAL": "not set",
        "os": "Fedora 43.0.0 [64-bit]",
        "os language": "en-US",
        "os type": "Fedora",
        "os version": "43.0.0"
      },
      "remediation": null,
      "durationMs": 16
    },
    "terminal.env": {
      "id": "terminal.env",
      "category": "terminal",
      "status": "ok",
      "summary": "terminal metadata was detected",
      "details": {
        "COLORTERM": "truecolor",
        "DISPLAY": "present",
        "TERM": "xterm-256color",
        "WAYLAND_DISPLAY": "present",
        "color output": "disabled (stdout is not a terminal)",
        "effective locale": "en_US.UTF-8",
        "multiplexer": "tmux 3.5a",
        "stderr is terminal": "true",
        "stdin is terminal": "true",
        "stdout is terminal": "false",
        "terminal": "unknown",
        "terminal size": "120x30",
        "tmux allow-passthrough": "off",
        "tmux client termname": "xterm-256color",
        "tmux extended-keys": "off",
        "tmux focus-events": "on",
        "tmux set-clipboard": "external",
        "tmux xterm-keys": "on"
      },
      "remediation": null,
      "durationMs": 42
    },
    "terminal.title": {
      "id": "terminal.title",
      "category": "title",
      "status": "ok",
      "summary": "terminal title configured",
      "details": {
        "terminal title activity": "true",
        "terminal title items": "activity, project-name, run-state, task-progress",
        "terminal title project source": "cwd",
        "terminal title project value": ".codex",
        "terminal title source": "configured"
      },
      "remediation": null,
      "durationMs": 0
    },
    "updates.status": {
      "id": "updates.status",
      "category": "updates",
      "status": "ok",
      "summary": "update configuration is locally consistent",
      "details": {
        "cached latest version": "0.139.0",
        "check for update on startup": "true",
        "dismissed version": "0.139.0",
        "last checked at": "2026-06-13T18:41:48.223648857Z",
        "latest version": "0.139.0",
        "latest version status": "current version is not older",
        "npm update target": "/home/agustinrromero/.config/nvm/versions/node/v22.21.1/lib/node_modules/@openai/codex",
        "update action": "npm install -g @openai/codex",
        "version cache": "/home/agustinrromero/.codex/version.json"
      },
      "remediation": null,
      "durationMs": 427
    }
  }
}

What issue are you seeing?

Codex CLI version: 0.139.0
Platform: Fedora 43, Linux x86_64
Auth mode: ChatGPT
Thread with investigation: 019ec25b-6c56-7802-a8eb-b82cf9a92450

My ~/.codex/config.toml contains:

model = "gpt-5.5"
model_reasoning_effort = "xhigh"
plan_mode_reasoning_effort = "xhigh"

Expected behavior:
Starting any new Codex session should use gpt-5.5 with xhigh reasoning effort. The statusline item "model-with-reasoning" should show "gpt-5.5 xhigh".

Actual behavior:
New Codex sessions start as "gpt-5.5 low". This is not just a statusline display issue. The rollout files record effort=low for newly started sessions.

This happens both for new sessions and resumed sessions. Manual workaround is to open /model and set gpt-5.5 xhigh after startup.

Repro steps:

1. Set ~/.codex/config.toml:
   model = "gpt-5.5"
   model_reasoning_effort = "xhigh"
   plan_mode_reasoning_effort = "xhigh"
2. Start a new Codex session.
3. Observe statusline with "model-with-reasoning".
4. Actual: shows "gpt-5.5 low".
5. Expected: should show "gpt-5.5 xhigh".

Command-line repro:
codex debug app-server send-message-v2 'Reply with exactly OK.'

Observed thread/start response includes:
model: "gpt-5.5"
reasoningEffort: "low"

I also tried:
codex debug app-server -c model_reasoning_effort='"xhigh"' send-message-v2 'Reply with exactly OK.'
codex exec -c model_reasoning_effort='"xhigh"' --json 'Reply with exactly OK.'

Those still created turns whose rollout files recorded effort=low.

Relevant debug thread ids:

• 019ec273-6a4f-75a3-b745-2d360b8b1f8f: debug app-server fresh thread, returned reasoningEffort=low
• 019ec273-b2d3-7903-8488-6bd1aa472d7b: debug app-server with -c override, still returned reasoningEffort=low
• 019ec274-15ff-7b80-8d97-70c7c272823b: codex exec run, rollout recorded effort=low

Impact:
The documented config key model_reasoning_effort appears to be ignored by the startup/thread-start path, so every new session starts with low reasoning unless I manually change it.

What steps can reproduce the bug?

Uploaded thread: 019ec25b-6c56-7802-a8eb-b82cf

What is the expected behavior?

Starting any new Codex session should use gpt-5.5 with xhigh reasoning effort. The statusline item "model-with-reasoning" should show "gpt-5.5 xhigh".

Additional information

No response